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CLAIM OF PRIORITY This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/341,806, filed on Apr. 5, 2010, which application is incorporated by reference herein, and is a Divisional Application of U.S. patent application Ser. No. 13/065,008, filed on Mar. 11, 2011, and which is incorporated by reference herein. FIELD The present disclosure relates generally to collectors for extreme ultraviolet (EUV) radiation, and in particular to EUV collector systems having enhanced EUV radiation collection capability. BACKGROUND ART EUV collector systems are used in EUV lithography systems to collect EUV radiation from an EUV radiation source and direct the EUV radiation to an aperture typically referred to as or associated with the intermediate focus. The radiation from the intermediate focus is then relayed by an illuminator to illuminate a reflective reticle. Radiation reflected from the illuminated reticle is then projected onto a wafer coated with a photosensitive material such as photoresist that records the reticle image. The wafer is then processed to form integrated microcircuits. FIG. 1 is a schematic diagram of a generalized configuration of a collector system 10 N that uses a normal-incidence collector (NIC) mirror MN. FIG. 2 is a schematic diagram of a generalized configuration of a collector system 10 G that uses a grazing-incident collector (GIC) mirror MG. Each collector system 10 N and 10 G has an EUV radiation source RS that emits EUV radiation 12 , a central axis A 1 , and an intermediate focus IF. Each collector system 10 N and 10 G is shown arranged adjacent an illuminator 20 that has an entrance aperture member 22 that defines an entrance aperture 24 . Entrance aperture member 22 is arranged at or near the intermediate focus IF. NIC mirror MN has a common input and output side 17 , while GIC mirror MG has an input end 16 and an output end 18 . In each collector system 10 N and 10 G, an important performance metric for EUV lithography is the amount and angular distribution of EUV radiation 12 the collector mirror MN or MG can deliver to the intermediate focus IF and through the entrance aperture 24 of illuminator 20 . As mentioned above, also of importance is the angular distribution of the EUV radiation 12 delivered through entrance aperture 24 of illuminator 20 . Entrance aperture 24 is used to define the limits of the intermediate focus IF so that illuminator 20 can have the proper field size and numerical aperture for illuminating the reticle (not shown). However, because neither type of collector system 10 N or 10 G can be made to perform perfectly, and because of magnification constraints on the system design, entrance aperture member 22 of illuminator 20 may also end up intercepting a substantial amount of EUV radiation 12 L, so that this intercepted EUV radiation 12 L is lost and is not utilized by the illuminator 20 , as illustrated in FIG. 3 . Also, due to design limitations or manufacturing imperfections in the collector system 10 N or 10 G, EUV radiation 12 passing through the entrance aperture 24 may not have the optimum angular distribution for use by the illuminator 20 . This lost or non-optimum EUV radiation 12 L is problematic because as much useable EUV radiation 12 as possible must be provided to illuminator 20 so that there is sufficient radiation to uniformly illuminate the reticle and adequately expose the photosensitive material (photoresist) on the wafer. SUMMARY The present disclosure is directed to EUV collector systems having enhanced EUV radiation collection capability. The enhanced EUV radiation collection capability is provided by a radiation-collection enhancement device (RCED) that is arranged at or adjacent an illuminator entrance aperture member that defines an entrance aperture. One RCED on either side of the illuminator entrance pupil (aperture) can be used, or two RCEDs on either side of the illuminator entrance pupil (aperture) can be used. The RCED can be configured so that EUV radiation that would otherwise not pass through the entrance aperture is redirected through the entrance aperture. In addition, by selectively configuring the inner surface of the RCED, a desired angular distribution (e.g., one that is more compatible with illumination system requirements) of the EUV radiation passing through the entrance aperture can be obtained. The RCED need not be circularly symmetric and can have one or more different types of inner surfaces (e.g., polished, planar, rough, undulating, etc.) that can grazingly reflect or otherwise re-direct incident EUV radiation. Some of this redirected EUV radiation can be used to illuminate discrete detectors that may be, for example, part of an EUV lithography alignment system. A roughened inner surface, for example, may be employed in certain applications, and on some or all of the at least one inner surface, where it is advantageous to scatter the otherwise less useful EUV radiation through the entrance aperture of the illuminator, for example to homogenize the radiation distribution in the far field. The one or more inner surfaces are thus referred to herein below also as “redirecting surfaces.” Some embodiments of the RCED include multiple inner surfaces, such as defined by concentric mirror shells. The RCED can be attached to the entrance aperture of the illuminator or can be spaced apart therefrom. The RCED can be configured (or be exchanged out for another RCED at a semiconductor manufacturing facility) to accommodate changes in the requirements on the EUV radiation being delivered to the illuminator. The RCED can be used to reduce the collection specifications on the collector mirror, making it easier to build and/or lower the cost of the collector system. The RCED is particularly useful in mitigating adverse affects due to collector system misalignments and perturbations. The RCED can be configured so that the captured light that would otherwise be lost or be less useful because of improper angular distribution can be redirected to the illuminator while still preserving (or at least substantially preserving) the etendue of the collector-illuminator system. An example RCED uses grazing-incident reflection to direct otherwise lost or less useful radiation through the entrance aperture of the illuminator. The redirecting surface of RCED can be highly polished and have a coating that maximizes the critical angle for grazing-incident reflection and enhances the collection solid angle. The coating may comprise a single layer or multilayer. Example coating materials include Ruthenium for a single-layer coating and Mo/Si for multilayer coatings. Thus, an aspect of the disclosure is a collector system for collecting and directing EUV radiation from an EUV radiation source through an aperture of an aperture member. The collector system includes a collector mirror configured to collect and direct the EUV radiation toward the aperture. The collector system also includes a radiation-collection enhancement device arranged at or adjacent the aperture and configured to collect a portion of the EUV radiation that would not otherwise pass through the aperture or would pass through the aperture at less than optimum angular distribution and redirect said portion of the EUV radiation through the aperture and with an angular distribution better suited for use by the illuminator. Another aspect of the disclosure is a method of collecting EUV radiation from an EUV radiation source and directing the EUV radiation through an aperture. The method includes collecting the EUV radiation from the radiation source and directing the EUV radiation to the aperture. The method also includes collecting a portion of the directed EUV radiation that would not otherwise pass through the aperture with at least one redirecting surface arranged adjacent the aperture, and redirecting said portion of EUV radiation through the aperture. Another aspect of the disclosure is a method of collecting EUV radiation in EUV lithography system having an aperture member with an aperture. The method includes generating the EUV radiation with an EUV radiation source. The method also includes collecting the EUV radiation from the EUV radiation source with an EUV collector and directing the EUV radiation to the aperture. A first portion of the directed EUV radiation is directed to pass through the aperture and a second portion of EUV radiation is directed to be intercepted by the aperture member. The method further includes collecting the second portion of EUV radiation with at least one first redirecting surface arranged adjacent the aperture, and redirecting the portion of EUV radiation through the aperture so that both the first and second portions of the directed EUV radiation pass through the aperture. Additional features and advantages of the disclosure are set forth in the detailed description below, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosure as described herein, including the detailed description which follows, the claims, as well as the appended drawings. The claims set forth hereinbelow constitute part of this specification and are incorporated herein directly and by reference. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a generalized prior art NIC collector system, illustrating how some of the focused EUV radiation does not make it through the -entrance aperture; FIG. 2 is a schematic diagram of a generalized prior art GIC collector system, illustrating how some of the focused EUV radiation does not make it through the entrance aperture member; FIG. 3 is a close-up cross-sectional view of the entrance aperture, illustrating how a portion of the EUV radiation generally directed to the intermediate focus is blocked by the entrance aperture member; FIG. 4 is a close-up cross-sectional view similar to FIG. 3 , but that includes an example RCED and that shows how the RCED redirects EUV radiation that would otherwise be lost to pass through the entrance aperture; FIG. 5A is a cross-section view of an example multi-shell RCED; FIG. 5B is a face-on view of the multi-shell RCED of FIG. 5A showing the spokes of a support structure (“spider”) for the two reflective shells; FIG. 6 is a schematic cross-sectional view of an example RCED that is spaced apart from the entrance aperture member and that is attached thereto via a support structure; FIG. 7 is a generalized NIC collector system similar to that of FIG. 1 , but with a RCED; FIG. 8 is a more detailed schematic diagram of an example EUV NIC collector system and that includes a RCED and a LPP EUV source; FIG. 9 is a generalized GIC collector system similar to that of FIG. 2 , but with a RCED; FIG. 10 is a more detailed schematic diagram of an example EUV GIC collector system and that includes a RCED and a LPP EUV source; FIG. 11 is an isometric view of an example conic RCED having circular symmetry and linear walls; FIG. 12 is a side cross-sectional view of an example conic RCED having circular symmetry and curved walls; FIG. 13 is a cross-section view of an example RCED, where the inner wall includes a plurality of facets and has non-circular symmetry; FIG. 14 is a cross-sectional view of an example RCED, where the inner wall includes a variety of different configurations such as planar, roughened, undulating and curved polished; FIG. 15 is a lateral cross-sectional view of an example RCED where the inner surface includes an undulating surface; FIG. 16 is similar to FIG. 12 but includes a roughened inner surface portion adjacent the output end; FIG. 17 is a schematic diagram similar to FIG. 2 and shows an example GIC collector system 10 G with illuminator 20 , illustrating the etendue limitations associated with transferring the EUV radiation from the radiation source to the illuminator; FIG. 18A is similar to FIG. 4 and illustrates an example embodiment where the RCED includes front and rear tapered bodies (sections) on either side of the aperture member; FIG. 18B is similar to FIG. 18A , except that the tapered bodies are separated from the aperture member; FIG. 19 is similar to FIG. 5A and illustrates an example RCED that includes multiple inner surfaces on either side of the aperture member; FIG. 20 is similar to FIG. 6 and illustrates another example RCED that includes a single front mirror shell and a single rear mirror shell as stood off from aperture member by respective stand-off support structures; FIG. 21 is similar to FIG. 16 and illustrates another example RCED having front and rear tapered bodies on either side of the aperture member; FIG. 22 is similar to FIG. 21 except that the RCED includes cooling channels on its outer surface; FIG. 23 is a schematic diagram of an EUV lithography system that uses an EUV collector system that employs the RCED of the present disclosure. The various elements depicted in the drawing are merely representational and are not necessarily drawn to scale. Certain sections thereof may be exaggerated, while others may be minimized. The drawing is intended to illustrate an example embodiment of the disclosure that can be understood and appropriately carried out by those of ordinary skill in the art. In the discussion below, the term “far field” is generally understood as being a substantial distance beyond the intermediate focus IF, e.g., 1 meter or greater. DETAILED DESCRIPTION FIG. 4 is a close-up, cross-sectional view of an entrance aperture member 22 of illuminator 20 similar to FIG. 3 , but showing an example RCED 100 arranged along central axis A 1 and adjacent entrance aperture member 22 on the side closest to EUV radiation source RS (not show in FIG. 4 ; see e.g., FIGS. 1 and 2 ). RCED 100 has a body portion 110 that includes a central aperture 114 that, along with body portion 110 , defines a tapered inner surface 120 that goes from wider at an input end 122 to narrower at an output end 124 , i.e., the taper generally narrows in the +Z direction. Inner surface 120 is designed to redirect at least a portion of EUV radiation 12 L so that this EUV radiation 12 L, which would otherwise not pass through entrance aperture 24 or that would pass through the entrance aperture 24 but with a less than optimum angle for use by the illuminator 20 , passes through entrance aperture 24 . In an example embodiment, inner surface 120 is smooth and covered with a coating 121 (single-layer or multi-layer, as described below) designed to enhance the reflectivity of the inner surface 120 at EUV wavelengths and the grazing incidence angles of EUV radiation 12 L. Various forms for RCED 100 are discussed in greater detail below. In an example embodiment, RCED 100 is or includes a grazing-incidence mirror element. EUV wavelengths typically range from 10 nm to 15 nm, with an exemplary EUV wavelength being 13.5 nm. In an example embodiment, inner surface 120 of RCED 100 is configured to match the numerical aperture (NA) requirements of illuminator 20 . In another example, RCED 100 can be adjusted or swapped out for a different RCED to accommodate changes (e.g., NA changes) in illuminator 20 . Generally, RCED 100 can be configured to match or otherwise accommodate particular angular distribution requirements of illuminator 20 . An aspect of the disclosure includes using RCED 100 to reduce the focusing requirements on the collector mirror (MN or MG) to allow the design of an illuminator 20 having a smaller entrance aperture 24 than could reasonably be accommodated by using a collector mirror (MN or MG) alone. This aspect of the disclosure can serve to simplify the collector requirements and/or illuminator design, which in turn reduces the collector and/or illuminator cost. In an example, RCED 100 is disposed adjacent entrance aperture member 22 of illuminator 20 , and can be attached to the entrance aperture member 22 or spaced apart therefrom. Attachment of RCED 100 to entrance aperture member 22 can be accomplished mechanically or magnetically so that the RCED 100 and the entrance aperture member 22 appear integrally formed, as shown in FIG. 4 . A spaced-apart RCED 100 (discussed below in connection with FIG. 6 ) may be preferred in some instances to achieve specific performance goals, or for ease of manufacture and assembly. In such case, a stand-off mechanism may be configured to achieve a precise separation distance. FIG. 5A is a cross-sectional view that illustrates an example RCED 100 that includes multiple inner surfaces 120 , such as formed by concentrically arranged mirror shells 103 - 1 and 103 - 2 . The concentric mirror shells 103 - 1 and 103 - 2 define two RCED apertures 114 - 1 and 114 - 2 . FIG. 5B is a face-on view of RCED 100 of FIG. 5A showing spokes 105 of a support structure (“spider”) that maintain the two mirror shells 103 - 1 and 103 - 2 in a spaced-apart and aligned configuration. Thus, RCED 100 generally includes at least one inner surface 120 , and in certain embodiments includes multiple inner surfaces 120 . FIG. 6 is a schematic cross-sectional view of an example RCED 100 that is spaced apart from entrance aperture member 22 of illuminator 20 , and that is attached thereto via a stand-off support structure 113 . In FIG. 5A and in FIG. 6 , the intermediate focus IF is shown as located in the plane PL defined by entrance aperture member 22 of illuminator 20 . The intermediate focus IF represents the central location of the focused EUV radiation distribution formed by the GIC collector system 10 G. It is noted here that while RCED 100 redirects at least a portion of EUV radiation 12 L that otherwise would not make it through entrance aperture 24 of illuminator 20 , in some embodiments RCED 100 is configured to also redirect through the entrance aperture 24 at least some EUV radiation 12 that would in fact have made it through the entrance aperture 24 had it not been redirected (see, e.g., one of the scattered EUV radiation 12 in FIG. 16 ). In such an embodiment, the redirection of EUV radiation 12 that would have made it through the entrance aperture 24 anyway will typically be done to change the angular distribution of the EUV radiation 12 passing through entrance aperture 24 and thereby make such EUV radiation 12 better suited to meet the angular input requirements of the illuminator 20 . In an example, the redirection of EUV radiation 12 is optimized to the angular distribution requirements of illuminator 20 . The output end 124 of RCED 100 can be smaller than entrance aperture 24 and still provide improved light collection. Experiments have shown that an RCED 100 with an output end 124 having a diameter of 4 mm passes substantially the same amount of EUV radiation 12 as a 6 mm entrance aperture 24 but resulted in a better angular distribution of the EUV radiation 12 in the far field. NIC Collector with RCED FIG. 7 shows a generalized NIC collector system 150 similar to NIC collector system 10 N of FIG. 1 , but with a RCED 100 arranged adjacent entrance aperture member 22 of illuminator 20 . FIG. 8 is a more detailed schematic diagram of an example NIC collector system 150 based on the generalized NIC collector system 10 N of FIG. 7 . FIG. 7 and FIG. 8 show the illuminator 20 acceptance angle θ that applies generally for both types of collector systems. The numerical aperture NA of illuminator 20 is given by NA=n·sin θ, where n is the refractive index of the medium, which is presumed to be a vacuum for an EUV lithography system (i.e., n=1). With reference to FIG. 8 , NIC collector system 150 includes a high-power laser source LS that generates a high-power, high-repetition-rate laser beam 11 having a focus F 11 . NIC collector system 150 also includes along a central axis A 1 a fold mirror FM and a large (e.g., ˜600 mm diameter) ellipsoidal NIC mirror MN that includes a surface S 1 with a multilayer coating 154 . The multilayer coating 154 provides good reflectivity at EUV wavelengths. NIC collector system 150 also includes a Sn source 160 that emits a stream of Sn pellets (or droplets) 162 that pass through and are irradiated by laser beam focus F 11 . In the operation of NIC collector system 150 , laser beam 11 from laser source LS irradiates Sn pellets (or droplets) 162 as the pellets (or droplets) pass through the laser beam focus F 11 , thereby produce a high-power laser-produced plasma source LPP-RS. Laser-produced plasma source LPP-RS typically resides on the order of a few hundred millimeters from NIC mirror MN and emits EUV radiation 12 , as well as energetic Sn ions, particles, neutral atoms, and visible, UV and infrared (IR) radiation. The portion of the EUV radiation 12 directed toward NIC mirror MN is collected by the NIC mirror MN and directed (focused) toward entrance aperture 24 to intermediate focus IF to form intermediate radiation distribution RD. As discussed above, some of the EUV radiation 12 (identified as 12 L) has a trajectory that would be blocked by entrance aperture member 22 . However, at least a portion of EUV radiation 12 L is collected by RCED 100 and redirected through entrance aperture 24 of illuminator 20 . This provides more EUV radiation 12 for forming a far-field radiation distribution RD, and thus more radiation for ultimately forming an image of the reticle at the wafer in an EUV lithography system. It is noted here that the EUV radiation directed toward entrance aperture 24 by the EUV collector system is not tightly focused precisely at intermediate focus IF and does not generally form a perfectly uniform far-field radiation distribution RD. Rather, the radiation distribution RD formed by the collector system at the intermediate focus IF is somewhat ill-defined due to imperfections (aberrations) in the particular collector system used, as well as scattering effects in the collector system. Further, illuminator 20 is typically designed so that it does not require as an input a sharply focused spot or a crisply defined disk. FIG. 12 , introduced and discussed below, shows an intermediate focus region IFR and that schematically illustrates a more realistic extent of the intermediate focus IF as caused by aberrations and scattering, and that is representative of the extent of an actual EUV radiation distribution. Illuminator 20 typically is configured to receive EUV radiation that passes through entrance aperture 24 with a specified angular distribution and uniformity. The illuminator 20 serves to condense and uniformize this EUV radiation for uniformly illuminating the reflective reticle (usually to within a few percent (e.g., between 2% and 5% uniformity). Thus, RCED 100 may be designed to capture additional misdirected EUV radiation from the collector mirror and redirect it to meet the illuminator specifications, thereby enhancing illuminator performance, and in particular increasing the amount of EUV radiation that can be effectively used to illuminate the reticle in an EUV lithography system. In an example embodiment, the NIC mirror MN or GIC mirror MG is formed with looser (reduced) tolerances than would otherwise be possible, and RCED 100 is used to compensate for the reduced tolerances, errors, misalignments, thermal distortions, etc. The combination of the collector mirror and RCED 100 can thus be used to meet the system tolerance at the intermediate focus plane PL for the radiation distribution RD. This approach makes it easier and likely less expensive to form the NIC or GIC mirror when such mirror is used in combination with a RCED 100 . GIC Collector with RCED FIG. 9 shows a generalized GIC collector system 180 similar to GIC collector system 10 G of FIG. 2 , but with a RCED 100 arranged adjacent entrance aperture member 22 . FIG. 10 is a more detailed schematic diagram of an example GIC collector system 180 based on the generalized GIC collector of FIG. 9 . GIC collector system 180 includes a laser source LS that generates a laser beam 11 . GIC mirror MG is shown as having GIC shells M 1 and M 2 arranged along central axis A 1 . In practice, one or more GIC shells can be used. A lens L and a fold mirror FM serve to direct laser beam 11 along central axis A 1 and through the GIC mirror MG in the −Z direction to a focus Fll on the opposite side of GIC mirror MG from laser source LS. In an example embodiment, GIC shells M 1 and M 2 include Ru coatings, which are relatively stable and can tolerate a certain amount of Sn coating. Note that fold mirror FM and laser beam 11 from laser source LS are shown located between GIC mirrors MG and the intermediate focus IF. An alternative arrangement places laser source LS and fold mirror FM between the input end 16 of GIC mirror MG and the laser beam focus F 11 . A high-mass, solid, moving Sn target 182 having a surface 184 is arranged along central axis A 1 so that a portion of the surface 184 of Sn target 182 is at focus F 11 . A target driver 186 (e.g., a motor) is shown for moving Sn target 182 by way of example. The laser beam- 11 incident upon surface 184 of Sn target 182 forms laser-produced plasma source LPP-RS. Moving Sn target 182 at high speed allows for laser beam 11 to be incident upon surface 184 of Sn target 182 at a different location for each laser pulse. The emitted EUV radiation 12 from laser-produced plasma source LPP-RS formed on Sn target 182 is generally in the +Z direction and travels through GIC mirror MG in the opposite direction of laser beam 11 , i.e., in the +Z direction. Some of EUV radiation 12 passes directly through RCED 100 and to intermediate focus plane PL to form radiation distribution RD, while other EUV radiation 12 L is collected by RCED 100 and directed through entrance aperture 24 by grazing-incidence reflection from reflective inner surface 120 . As with the NIC collector system 150 , this configuration provides more useful radiation (e.g. an angular distribution the better meets the illuminator specifications) passing through the intermediate focus aperture radiation for forming radiation distribution RD and thus more radiation for ultimately forming an image of the reticle at the wafer in an EUV lithography system. While the example EUV radiation source has been described above as an LPP EUV radiation source, a discharge-produced plasma (DPP) EUV radiation source can also be used in connection with the embodiments of the present disclosure. Example RCEDs RCED 100 can have a wide range of configurations that have a generally tapered shape in the +Z direction when placed in front of (i.e. on the collector side of) the entrance aperture member 22 , and a generally shape in the -Z direction when placed behind (i.e. on the illuminator side of) the entrance aperture member 22 . If the RCED 100 is intended to homogenize and otherwise improve the angular distribution of EUV radiation in the far field behind entrance aperture member 22 of illuminator 20 , then it can have a fairly complex inner surface configuration. For example, the inner surface configuration can include a precisely contoured reflecting surface or an undulating surface or even a roughened inner surface configured to uniformize and otherwise optimize the EUV radiation coming from, for example, distributed shells of a multi-shell GIC mirror MG. On the other hand, if RCED 100 is intended to distribute EUV radiation to larger angles behind entrance aperture member 22 to optionally illuminate an alignment structure beyond the field of the illuminator 20 , then the inner surface 120 of RCED 100 can be preferably configured to maximize the angles passing through entrance aperture 24 of illuminator 20 . Or, if RCED 100 is only intended to maximize the amount of EUV radiation 12 through the entrance aperture 24 of illuminator 20 , then inner surface 120 can be designed to have one or more surface configurations that achieve this goal. FIG. 11 is an isometric view of an example RCED 100 that illustrates an example conic RCED 100 that has a reflective inner surface 120 with a linear taper. RCED 100 has a central axis AC. A coating 121 is shown on inner surface 120 . The linear taper can be configured to correspond (e.g., match) the NA or the angular distribution of illuminator 20 . A simple version of RCED 100 includes a polished inner surface 120 that, along with coating 121 , grazingly reflects EUV radiation 12 L. FIG. 12 is a longitudinal cross-sectional view of an example RCED 100 that illustrates an example where the RCED 100 that has a reflective inner surface 120 with a curved (i.e., flared) taper. As discussed above, the curved taper can be configured to correspond (e.g., match) the NA or the required angular distribution of illuminator 20 . FIG. 13 is lateral cross-sectional view of an example RCED 100 that has an inner surface 120 that is not rotationally symmetric and that has a plurality of (e.g., eight) inner surfaces 120 F- 1 through 120 F- 8 . The faceted inner surface 120 F can be, for example, linearly tapered or curved tapered. FIG. 14 is similar to FIG. 13 , and shows an example RCED 100 having a variety of inner surfaces 120 , such as one or more inner surface 120 F, an undulating or grooved inner surface 120 G, a roughened inner surface 120 R and a polished, curved inner surface 120 P. Such a multi-form inner surface 120 may be employed for specialized applications. FIG. 15 is a lateral cross-sectional view of an example RCED 100 where inner surface 120 includes an undulating or grooved inner surface 120 G. Such an inner surface 120 G can serve to smooth out or otherwise optimize the far-field EUV radiation distribution RD without using scattering from a high-spatial-frequency roughened surface. FIG. 16 is similar to FIG. 12 , but includes a portion of roughened inner surface 120 R adjacent output end 124 . The portion of Roughened surface 120 R serves to provide wider scattering angles for EUV radiation 12 L than a polished inner surface 120 (e.g., 120 P; see FIG. 14 ), and serves to uniformize or otherwise improve (or optimize) the EUV radiation distribution RD at entrance aperture 24 of illuminator 20 . Body portion 110 of RCED 100 may be formed from a metal, a ceramic, a plastic or a glass or glass-like material. In an example, body portion 110 (including inner surface 120 ) of RCED 100 is smooth and has a controlled high-spatial-frequency roughness (as understood in the art of EUV mirrors) to control scattering. However, example embodiments include cases where inner surface 120 (and optional coating 121 ) are configured with a surface roughness configured to generate a select scattering (e.g., a broad scattering) of EUV radiation collected by the RCED 100 , as discussed above in connection with FIG. 16 . If body portion 110 of RCED 100 is made of a plastic or other material that can be cast, then it can indeed be made very inexpensively and with a high degree of surface smoothness limited only by the smoothness of the master cast. Such a plastic or other non-metal RCED substrate can be coated with a high-atomic-number material (e.g., Ruthenium) to improve or optimize the grazing incidence reflection from the inner surface 120 of RCED 100 . If RCED 100 is to be subjected to a significant thermal load, then a preferred body material may be a metal. In an example embodiment, a metal body portion 110 of RCED 100 has an inner surface 120 that is polished to a desired smoothness, or is electroformed. Example metals for body portion 110 of RCED 100 include stainless steel, nickel, copper, aluminum, and like metals that can be highly polished. Another example material for body portion 110 of RCED 100 is a thermally resistant material such as ZERODUR. In an example embodiment, body portion 110 of RCED 100 is configured to support a cooling mechanism, such as cooling channels 129 (see FIG. 4 ). As discussed above, inner surface 120 may include a reflective coating 121 tailored to optimize the reflectivity of EUV radiation 12 at grazing incidence. While Ru is a preferred coating material, other high-atomic-number materials—such as Cu, Au, Pd, Sn, Pt, and Au—can also be used, as long as the specific application would not prohibit the use of such a coating. In addition, a resonant multilayer coating 121 can be used. Such a coating 121 would serve to broaden the acceptance angle and can increase the efficiency of RCED 100 . An example multilayer coating 121 includes layers of Mo and Si. RCED with Front and Rear Sections The amount of EUV radiation 12 that can be transferred from radiation source RS through GIC mirror MG and to illuminator 20 is limited by the overall system etendue , and in particular the design input etendue of the illumination system. However, in the case of a grazing incidence collector it is worth noting that the etendue of the individual GIC shells (M 1 , M 2 , etc.) will typically be considerably smaller than that of the illuminator 20 , and that the far-field EUV radiation distribution RD from the GIC will have gaps due to the nature of the separated shells. Thus, much of the EUV radiation 12 P (Refer to FIG. 17 ) that would be lost can be recovered by RCED 100 without violating the etendue principle, and in particular without exceeding the etendue of the illuminator 20 . Indeed, the RCED 100 can be used to redistribute the angular distribution of the far field radiation to better match the input angular distribution specifications of the illuminator 20 without violating the optical invariant (i.e., the etendue principle). As discussed above, much of the recovered EUV radiations 12 P gets directed into dark spaces on either side of the unaided far-field images formed by the GIC mirrors MG. This serves to homogenize and further optimize the far-field radiation distribution RD. FIG. 17 is a schematic diagram similar to FIG. 2 and shows an example GIC collector system 10 G with illuminator 20 . Illuminator 20 and entrance aperture member 22 define input and output acceptance angle limits 19 -I and 19 -O on the input and output sides of the entrance aperture 24 . Even for the EUV radiation 12 that passes through entrance aperture member 22 , some of this EUV radiation 12 P has an angle relative to central axis A 1 that precludes this radiation from entering and being processed by illuminator 20 . This is because the image formation process associated with GIC collector system 10 G is imperfect and is generally directed to trying to get as much EUV radiation 12 as possible from radiation source RS to illuminator 20 . With reference to FIG. 18A , in an example embodiment RCED 100 includes front and rear sections 110 F and 110 R on either side of entrance aperture member 22 . FIG. 18B is similar to FIG. 18A , except that the front and rear sections 110 F and 110 R are separated from entrance aperture member 22 . FIGS. 18A and 18B illustrate EUV radiation 12 that passes through RCED 100 with no bounces ( 12 ), one bounce ( 12 L) and two bounces ( 12 P). Note that the front and rear sections 110 F and 110 R can also be considered separate RCEDs with possibly different curvatures or patterning on the front RCED versus the rear RCED. Accordingly, so the description of these sections 110 F and 110 R as being part of one RCED 100 or as being two different RCEDs is the same, and in some instances herein, front and rear RCED sections are referred to simply as front and rear RCEDs. In an example, front and rear sections 110 F and 110 R are axially tapered in opposite directions, as shown. FIG. 19 is similar to FIG. 5A and illustrates an example RCED 100 that includes multiple inner surfaces 120 on either side of entrance aperture member 22 , such as formed by two sets of concentrically arranged mirror shells, namely front mirror shells 103 F- 1 and 103 F- 2 , and rear mirror shells 103 R- 1 and 103 R- 2 . Each of the mirror shells 103 F- 1 , 103 F- 2 , 103 R- 1 and 103 R- 2 can be considered sections of RCED 100 or even a separate RCED 100 . Once again, it is noted that front section 110 F may have one or more surfaces whereas rear section 110 R may have a number of surfaces different from the front section 110 F. Similarly, front section 110 F may be separated from the entrance aperture member 22 while rear section 110 R may be attached to or separated from the entrance aperture member 22 , or vice versa. FIG. 20 is similar to FIG. 6 and illustrates another example RCED 100 that includes a single front mirror shell 103 F and a single rear mirror shell 103 R as stood off from entrance aperture member 22 by respective stand-off support structures 113 F and 113 R. Front and rear mirror shells 103 F and 103 R can also be considered as separate RCED sections or as separate RCEDs with different curvatures, different stand-offs, and a different number of surfaces between the front and rear RCEDs, etc. FIG. 21 is similar to FIG. 16 and illustrates another example RCED 100 having front and rear sections 110 F and 110 R on either side of entrance aperture member 22 . Front and rear sections 110 F and 110 R have respective axial lengths LF and LR, and in an example have an axial taper, as shown. FIG. 22 is the same as FIG. 21 and includes cooling channels 129 arranged on each of the sections 110 F and 110 R to cool these sections by flowing a cooling fluid through the cooling channels 129 . In an example, one of the cooling channels 129 runs around the input end 122 . As discussed above, front and rear sections 110 F and 110 R can also be considered as separate RCED sections or as separate RCEDs with different curvatures, different cooling configurations, different stand-offs, and different number of surfaces between the front and rear RCEDs, etc. A desirable feature in a collector system is the ability to filter out unwanted broadband infrared radiation 240 generated by the EUV radiation source RS. Thus, with reference again to FIG. 22 , an IR filter 250 is disposed adjacent input end 122 or output end 124 of front section 110 F. Other locations for IR filter 250 are also possible. IR filter 250 is configured to filter out broadband infrared radiation 240 that may also be collected and reflected by the grazing incidence or normal incidence collector and delivered to entrance aperture member 22 . In an example embodiment, IR filter 250 comprises a low-density, free-standing grating having crossed-grating lines 252 (see insets, FIG. 22 ) and a support frame 254 . The crossed-grating lines 252 have a period smaller than the wavelength of infrared radiation 240 . If the areal density of crossed-grating lines 252 is relatively low (e.g. only 3% areal density coverage with metal crossed-grating lines 252 ) then the filtration of the infrared radiation 240 can be high while letting most (e.g. ˜97%) of the EUV radiation pass through. Where IR filter 250 has metal crossed-grating lines 252 , it can be thermally attached to the cooled RCED 100 to carry away any thermal load to which it may be subjected. Thus, an aspect of the methods disclosed herein includes filtering infrared radiation 240 from the EUV radiation source RS immediately upstream or downstream of the at least one redirecting surface associated with RCED 100 . An example method of making a suitable crossed-grating-based IR filter 250 is now described. To filter infrared radiation 240 while transmitting EUV radiation, the grating period needs to be less than the IR radiation wavelength. Also, since a substrate will generally absorb EUV radiation, it is preferred that the grating be freestanding, or alternatively, the supporting substrate be very thin (i.e., membranous) and be made of a material that has low absorption at 13.5 nm. For example, a half-micron thick Si membrane would reduce the EUV transmission at 13.5 nm by about a factor of 2×. If a 0.1 micron thick Si membrane were used, it would have a transmission at 13.5 nm of about 87%, which might be deemed acceptable. For a linear grating in the vertical (Y) direction, polarization components of the infrared radiation 240 in the Y direction would get reflected, with some absorption in the metal of the grating depending on its conductivity. To reflect all polarization components, a crossed-grating is employed, i.e., grating lines running in both the X and Y directions. All wavelengths below the period of the grating would pass thru the grating spaces. Any EUV radiation that hits the grating lines will get absorbed, while that which passes through the spaces is transmitted. If the grating lines represent only 5% of the grating area, then 5% of the EUV radiation will be absorbed, 95% will be transmitted, and substantially no infrared radiation at wavelengths longer than the grating period will be transmitted. To produce a master pattern of grating lines with the appropriate period and the appropriate linewidths, a suitable substrate is selected. An example substrate is a silicon wafer or thin glass. The wafer is coated with a thin chrome layer (e.g., less than 0.1 micron thick) as an adhering layer. The thin chrome layer is then coated with a thin (e.g., about 0.1 micron) plate-able metal layer, such as gold or other suitable metal. The metal layer is then coated with photoresist of a desired thickness. A master grid pattern with the appropriate period is lithographically formed in the photoresist layer. Developing the photoresist provides the negative of the grating pattern in the photoresist atop the plate-able metal layer. The photoresist layer is then plated with the same plate-able metal as the underlying plate-able metal layer. The photoresist is then washed away, e.g., using acetone. The resulting structure is now a thick metal grating atop of the approximately 0.2 micron thick chrome and plate-able metal layers supported by the substrate. A support structure can be attached to the outside of the metal grating structure so that the metal structure can be free-standing inside of the support structure. An example support structure is a washer that is epoxied to the metal grating structure. The grating structure periphery can be made to be thick and free of grating lines. At this point, chrome and plate-able metal layers are removed, e.g., using a liquid or beam etch process. Next, the substrate is removed, e.g., by a liquid etch suitable for the particular substrate (e.g., HF for a glass substrate). The result is a free-standing, metal crossed grating supported around its outer edge so that it can be handled and also mounted into position relative to the RCED 100 . EUV Lithography System with EUV Collector and RCED FIG. 23 is an example EUV lithography system (“lithography system”) 300 according to the present disclosure. Example lithography systems are disclosed, for example, in U.S. Patent Applications No. U.S. 2004/0265712A1, U.S. 2005/0016679A1 and U.S. 2005/0155624A1, which are incorporated herein by reference. Lithography system 300 includes a system axis AS and an EUV radiation source RS that emits working EUV radiation 12 nominally at λ=13.5 nm. Lithography system 300 also includes along system axis AS an EUV collector mirror (NIC or GIC) 310 and a RCED 100 as described above. EUV collector mirror 310 and RCED 100 comprise a collector system 312 . Collector system 312 also optionally includes EUV radiation source RS. EUV radiation source RS may include, for example, a LPP EUV radiation source or a DPP EUV radiation source. An illuminator 20 with an input end 20 A and an output end 20 B is arranged along system axis AS and adjacent and downstream of collector system 312 . Illuminator 20 includes entrance aperture member 22 with entrance aperture 24 . EUV collector mirror 310 (shown configured as a GIC mirror for illustration) collects EUV radiation 12 from EUV radiation source RS located at source focus SF. The collected EUV radiation 12 is directed to entrance aperture 24 , with the intention of forming a radiation distribution RD at intermediate focus IF. RCED 100 operates as described above to enhance the EUV radiation 12 focusing process by redirecting at least a portion of EUV radiation 12 L that would otherwise not pass through entrance aperture 24 to the illuminator 20 , to pass through entrance aperture 24 . Thus, illuminator 20 receives at input end 20 A EUV radiation 12 at the intermediate focus plane PL from radiation distribution RD and outputs at output end 20 B a more uniform EUV radiation 12 ′ (i.e., condensed EUV radiation) to a reflective reticle 336 . Where lithography system 300 is a scanning type system, EUV radiation 12 ′ is typically formed as a substantially uniform line of EUV radiation at reflective reticle 336 that scans over the reflective reticle 336 . It is also noted that illuminator 20 may image a portion of the EUV radiation passing through entrance aperture 24 to a region outside of the reticle patterned area (e.g., in a kerf), and that this EUV radiation (denoted 12 ′A in FIG. 23 ) can be used for alignment purposes, e.g., by being incident upon reticle alignment marks that reside outside of the patterned area used for forming microcircuit features. In an example embodiment, EUV radiation 12 ′A is detected by a photodetector 360 , which forms electronic signals S 360 that can be processed (e.g., in a computer, not shown) to perform alignment. A projection optical system 326 is arranged along (folded) system axis AS downstream of illuminator 20 and reflective reticle 336 . Projection optical system 326 has an input end 327 facing output end 20 B of illuminator 20 , and an opposite output end 328 . Reflective reticle 336 is arranged adjacent the input end 327 of projection optical system 326 and a semiconductor wafer 340 is arranged adjacent output end 328 of projection optical system 326 . Reflective reticle 336 includes a pattern (not shown) to be transferred to semiconductor wafer 340 , which includes a photosensitive coating (e.g., photoresist layer) 342 . In operation, the uniformized EUV radiation 12 ′ irradiates reflective reticle 336 and reflects therefrom, and the reticle pattern is imaged onto surface of photosensitive coating 342 of semiconductor wafer 340 by projection optical system 326 . In a lithography system 300 , the reticle image scans over the surface of photosensitive coating 342 to form the pattern over the exposure field. Scanning is typically achieved by moving reflective reticle 336 and semiconductor wafer 340 in synchrony. Once the reticle pattern is imaged and recorded on semiconductor wafer 340 , the patterned semiconductor wafer 340 is then processed using standard photolithographic and semiconductor processing techniques to form integrated circuit (IC) chips. Note that the components of lithography system 300 are shown lying along a common folded system axis AS in FIG. 23 for the sake of illustration. One skilled in the art will understand that there can be more than one fold in lithography system 300 , and that there can be an offset between entrance and exit axes for the various components such as for illuminator 20 and for projection optical system 326 . It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

A collector system for extreme ultraviolet (EUV) radiation includes a collector mirror and a radiation-collection enhancement device (RCED) arranged adjacent an aperture member of an illuminator. The collector mirror directs EUV radiation from an EUV radiation source towards the aperture member. The RCED redirects a portion of the EUV radiation that would not otherwise pass through the aperture of the aperture member or that would not have an optimum angular distribution, to pass through the aperture and to have an improved angular distribution better suited to input specifications of an illuminator. This provides the illuminator with greater amount of useable EUV radiation than would otherwise be available from the collector mirror alone, thereby enhancing the performing of an EUV lithography system that uses such a collector system with a RCED.

FIELD OF THE INVENTION The invention generally relates to a process for maintaining a consistent surface on and extending the lifespan of a continuous rubber blanket. More specifically, the invention relates to a process and apparatus for continuously conditioning a continuous rubber blanket such as the variety used in the compressive shrinkage of webs of material. BACKGROUND Many textile fabrics, and in particular those made wholly or partly from cellulosic fibers, have a tendency to shrink undesirably as a result of becoming wet or undergoing conventional laundering processes. To obviate undesirable shrinking, many such fabrics are customarily treated using a compressive or compaction shrinkage process, in order to pre-shrink the fabrics and increase their stability. Examples of compressive shrinkage processes are described in U.S. Pat. No. 2,146,694 to Wrigley, et al. and U.S. Pat. No. 3,469,292 to Hojyo, U.S. Pat. No. 4,156,955 to Joy, and U.S. Pat. No. 4,446,606 to Lawrence et al, the disclosures of which are incorporated herein by reference. Also, a popular compressive shrinkage process is known by the tradename SANFORIZE. In compressive shrinkage processes, a fabric web is typically laid out over the working face of a thick endless rubber blanket so that it is free of folds or wrinkles. The rubber blanket is positioned on a plurality of rotatable rolls which support the blanket along its 10 bearing surface, and the blanket is typically conveyed along an endless path by way of a driven cylinder which contacts the outer blanket surface. In this way, the fabric web placed on the outer surface of the blanket is caused to be carried through a number of processing stations. First, the fabric is typically moistened, then it is compressed along with the blanket between a roll and a heated cylinder or shoe. As the fabric and blanket pass between the nip (i.e., the point of contact between the two contiguous elements) and the blanket is compressed, adjacent portions of the outer surface of the blanket are caused to be extended. As the blanket and fabric leave the roll, the blanket contracts, and the fabric is forced to follow suit. As a result, the yarns in the warp direction are caused to shorten, and the filling yarns are pushed upwardly, thereby mechanically shrinking the fabric. The fabric is then fed to a dryer, where it is dried in its preshrunk condition. Because the rubber blanket is endless, a web of fabric can be processed in a continuous manner. However, the surface of the rubber blanket must be cooled following contact with the heated cylinder before it again contacts the fabric web. Such cooling is generally performed by applying water to the blanket as it travels between the point of web removal and the point of untreated fabric web lay-down. Because too much moisture on the blanket can interfere with proper fabric conditioning, it is generally necessary that the amount of water on the blanket working surface be closely controlled. Generally this is performed by water removal rolls, which squeegee the excess water from the cooled blanket. Because it is important that the blanket stay properly lubricated, water is often added to the bearing surface of the blanket at various positions throughout the process, e.g., before the point of fabric lay-down and following contact of the blanket with the heated cylinder. As should be apparent, the rubber blankets are exposed to great stresses during the compression shrinkage process as a result of the repeated heating and cooling, the tensions at which the blanket must be run on the machine, the compression forces endured by going through the nip, and the repeated wetting operations. Under these conditions, the working surface of the blanket slowly oxidizes. This results in an increase in hardness and a decrease in wettability. In addition, finishes present on the fabric surface are often transferred to the rubber surface. Over a relatively short time this finish tends to form a glaze on the rubber surface, further decreasing the wettability and friction characteristics of the surface. As will be readily appreciated by those of ordinary skill in the art, the reduction in frictional characteristics on the web-contacting surface of the blanket reduces its effectiveness in gripping the fabric web. As a result, the surface characteristics of the blanket must be modified to restore its frictional characteristics in order that it can continue to properly and uniformly process fabrics. For example, in commercial applications, once the blanket hardness has been found to deviate upwardly or downwardly about 12% from its original level, blanket manufacturers recommend that the blanket be ground to remove the dead rubber on its surface. In this way, the surface of the blanket is prevented from becoming too slick or from losing its ability to grab hold of the fabric being treated. Such grinding is usually performed by stopping the machine and backing the rubber blanket up against a rotatable roll covered with abrasive material (e.g., grinding cloth or sandpaper), which grinds the working face of the rubber blanket until the dead rubber area has been removed. Typically the grinding process requires the removal of about a sixteenth of an inch of the blanket surface with each grinding. Because, for example, a blanket which begins at 3 inches thick usually must remain at least two inches thick to work effectively, the number of grindings is thus very limited. As a result, the life of the rubber blanket used in these types of apparatus can be undesirably short. It can also be appreciated that intermittent grinding of the blanket produces a surface that is variable over time, resulting in a greater amount of variability in compressive efficiency, and greater variability in the shrinkage characteristics of the final product. As the overall pre-shrinkage may need to be increased to avoid producing out-of-specification goods, the fabric yield will be less. In addition, small cuts and nicks in the blanket can form and grow over time due to oxidation and the constant stretching and releasing of the blanket rubber surface. When the blanket is ground, additional blanket thickness must be sacrificed in order to insure that all cracks are removed. This contributes to a shorter blanket life. During grinding of the blanket, production is halted, as the blanket must be ground dry to avoid premature decomposition or destruction of the grinding cloth or sandpaper. In addition, a considerable amount of rubber debris is formed due to the conventional grinding process. A heavy dusting of talc is typically applied during the grinding process, to reduce the friction and heat generated and to keep the blanket from becoming too sticky during the grinding operation. This talc and surplus rubber material must be cleaned from the blanket to prevent them from collecting on fabrics or materials being processed after the grinding operation. In addition, blankets typically require frequent cleaning to remove the build-up of baked-on fabric finishes, oils, and the like. Again, production must be halted so that the blanket may be cooled, and detergents applied. However, if such finishes and oils are not removed on a timely basis, they can adversely affect the process performance as well as contribute to the decomposition of the rubber blanket. The requirements of frequent cleaning and grinding prevent the rubber blanket machine from operating in-line with modern webprocessing equipment, which generally operate continuously, and which cannot economically be stopped to accommodate belt cleaning and grinding. A typical blanket grinding operation takes about 8 hours to perform, which is significant lost time from a fabric producer's perspective. Therefore, the grinding operation is recognized as being a significant source of machine downtime. One attempt to increase the lifespan of blankets in compressive shrinkage apparatus is described in U.S. Pat. No. 5,791,029 to Maker, the disclosure of which is incorporated herein by reference. The '029 patent describes a rubber blanket construction having a bearing face which is beveled. The patentee describes that this construction reduces the tendency of the edges of the blanket to curve upwardly when the blanket is tensioned to perform a grinding operation and reduces the tendency of the edges to crack. While this method may reduce the tendency of the blanket to crack, it does not overcome the need for frequent blanket cleaning and grinding. SUMMARY OF THE INVENTION The present invention is directed to a process and apparatus for continuously conditioning the working face of a rubber blanket such as that used on compressive shrinkage apparatus. As a result, the useful life of the blanket can be extended to a significant extent. (For purposes of this invention, the term “rubber blanket” is intended to encompass all blankets useful in compressive shrinkage type apparatus, whether they are substantially all rubber, partially rubber, made from synthetic rubber, or the like. Similarly, although the term “continuously conditioning” is used, it is to be noted that this terminology encompasses substantially continuous conditioning methods of a like nature as well, and in particular, when the user has elected to discontinue the conditioning briefly for various reasons.) Because the process of the instant invention can be readily incorporated into the regular machine processing operations (i.e., the web processing operation), the need for machine downtime to allow blanket grinding can be eliminated. This in turn enables the apparatus to be used more efficiently, by not requiring the machine downtime typically required for conventional blanket conditioning methods. In addition, existing compressive shrinkage machines can be readily retrofit to form the apparatus of the invention, thereby minimizing associated costs. The invention achieves the above-noted advantages through the provision of an abrasive device, and in particular an abrasive roll, on the apparatus such that the abrasive roll is in contact with the working surface of the rubber blanket during regular operation of the compressive shrinkage apparatus during its regular web treatment process. In this way, the abrasive roll can provide a low level of consistent grinding for continuous periods of time. In a preferred form of the process, the abrasive roll contacts the blanket at substantially all times during operation of the machine and advancement of the blanket. Alternatively, the abrasive roll could be provided to contact the blanket less than 100% of the time the blanket is advancing (although constant contact is generally preferred.) The speed of the abrasive roll relative to that of the working surface of the blanket can be adjusted to provide the desired amount of grinding. Preferably, only a small differential in speeds exists, such that a constant low level of grinding can be achieved. Similarly, the pressure of the abrasive roll against the blanket can be selected to achieve an optimal level of grinding. Furthermore, it is particularly preferred that the rotation of the abrasive roll is directly associated with the travel of the blanket, so that the grinding operation is halted simultaneously upon the cessation of blanket movement. In this way the formation of irregularities in the blanket surface as a result of the grinding operation can be minimized. In other words, in the embodiments of the invention where the grinding is directly associated with the blanket movement, the risk that the blanket will cease movement while grinding continues can be avoided (thereby avoiding the risk that irregular regions of greater grinding are formed.) Surprisingly, a working surface having characteristics indistinguishable from that of the usual high speed dry grinding using talc may be achieved and consistently maintained, even in the hot and wet conditions typically associated with compressive shrinkage processes. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of one embodiment of an apparatus of the instant invention. DETAILED DESCRIPTION In the following detailed description of the invention, specific preferred embodiments of the invention are described to enable a full and complete understanding of the invention. It will be recognized that it is not intended to limit the invention to the particular preferred embodiment described, and although specific terms are employed in describing the invention, such terms are used in a descriptive sense for the purpose of illustration and not for the purpose of limitation. With reference to the drawing, FIG. 1 illustrates one embodiment of apparatus according to the present invention. Although described specifically to correspond with the illustrated apparatus, it is noted that the features of the invention can be included with other similar types of apparatus having a continuous blanket and in particular, other types and configurations of compressive shrinkage apparatus. In addition, although described in connection with the compressive shrinkage of textile fabrics (such as woven, knit and nonwoven fabrics), it is noted that the invention would have application to other types of compressive shrinkage apparatus, such as those designed to process paper webs. The apparatus, shown generally at 10 , desirably includes many of the elements included in a conventional compressive shrinkage apparatus. In particular, the apparatus 10 desirably includes a first roll 12 , which cooperates with a heated drum 14 to form a nip 16 therebetween. The apparatus also desirably includes a tensioning roll 18 , an idler roll 20 , and water removal rolls 22 . A rubber blanket 24 is positioned so that it extends around the rolls 12 , 18 , 20 and 22 in the manner illustrated. In this way, the rolls define a continuous path through which the blanket 24 travels during the web processing operation. As illustrated, a web W is fed into the apparatus so that it extends in an overlying relationship to the web-contacting surface 24 a of the blanket. In this way, the web of material W is compressed between the nip roll 12 and the heated drum 14 along with the blanket 24 , so that it is compressively shrunk in a conventional manner. In the illustrated embodiment of the invention, a first roll 26 is placed in pressure contact with the web-contacting surface of the blanket 24 , and is allowed to be driven by the blanket at a synchronous surface speed. As will be appreciated by those of ordinary skill in the art, the surface texture and/or pressure at which the drive roll contacts the blanket enables the roll to be rotated upon an advancing motion by the blanket. Preferably, the surface of this first roll is abrasive (e.g. by way of a stippled or textured surface, or more preferably through the provision of grit particles on the surface of the roll.) This drive roll 26 is then differentially geared to a second abrasive roll 28 , also in pressure contact with the web-contacting surface of the blanket 24 , so that it is driven at an asynchronous surface speed to the blanket. First and second backup rolls 30 , 32 may also be provided in order to provide or increase pressure between the drive and abrasive rolls 26 , 28 . In this way, the abrasive roll 28 serves to remove a portion of the web-contacting surface 24 a of the blanket as the blanket circulates along its web-processing endless pathway. Therefore, grinding can be performed during the normal compressive shrinkage operation rather than as a separate operation. As will be appreciated by those of ordinary skill in the art, by increasing the pressure of the abrasive roll 28 against the blanket, the span of contact between the roll and blanket is increased, thereby also increasing the rate of grinding. Furthermore, the differential speed (defined as the magnitude of the difference in the surface speed between the first and second rolls 26 , 28 , divided by the surface speed of the faster abrasive roll and multiplied by 100 percent) may vary from about 2 to 95 percent, but should preferably lie in the range of 5 to 50 percent, and most preferably in the range of about 8 to 25 percent. The pressure of the abrasive roll against the blanket is preferably about 20 to about 2000 pounds, and more preferably about 100 to about 1500 pounds, and most preferably about 200 to about 1000 pounds, such pressures being selected depending on, among other things, the speeds at which the machine is to be run and the amount of grinding desired. The abrasive rolls may be geared together, but are preferably coupled by means of a synchronous (e.g. toothed) belt. However, other means for achieving the speed correlation between the rolls may be utilized within the spirit of the invention. As noted above, pressure of the abrasive rolls against the blanket is preferably achieved by use of a back-up roll, most preferably with an individual back-up roll for each abrasive roll. In this way, a nip is created with the blanket running therebetween, with the abrasive roll loaded against the back-up roll, preferably by means of air cylinders. Two nips are preferably created. Utilizing this arrangement and two abrasive rolls, one can increase the pressure at one nip relative to the other, to thereby determine which roll serves as the drive roll, and which serves as the conditioning roll. This may be done intermittently, if desired, in order that the blanket can be abraded in both the forward and reverse directions. As a further alternative, the abrasive roll 28 could be independently controlled by way of supplemental drive means, to grind the blanket while it proceeds through its regular web processing operation. However, the use of an abrasive roll which is rotated in response to blanket motion is preferred, since this reduces machinery complexity and reduces the opportunity for grinding-induced blanket defects. Furthermore, additional rolls could be utilized as desired, to provide additional amounts of and locations of grinding. In addition, although illustrated as being provided relatively close to the web take-off location, it is noted that the abrasive roll(s) can be provided anywhere other than web-contacting portions of the apparatus, within the scope of the invention. The drive and abrasive rolls each desirably have abrasive surfaces. In particular, the abrasive rolls are preferably coated with diamond grit in the range of 60 to 400 grit, and more preferably in the range of 100 to 220 grit. The grit is preferably bonded directly to the roll by means of a metal matrix, where the metal is resistant to corrosion. In a preferred form of the invention, the metal matrix is selected from the group consisting of nickel, chromium, other metals with similar physical characteristics, or combinations thereof. The grit used for the drive roll and the conditioning roll may be different, thus allowing abrasion with two different grit sizes if the functions of the drive and conditioning rolls are interchanged by varying the nip pressures. While a single roll may be used as a conditioning roll, (with a preferable surface speed of between 2 and 200 percent of blanket working surface speed) by driving the roll by means of a variable speed motor, or by belt or geared connection of drive elements of the compressive shrinkage apparatus itself, it is preferred that the conditioning roll be surface driven by the blanket, as this insures that the blanket is not accidentally damaged during a stoppage, when the roll might otherwise continue to rotate after the blanket has stopped. Surface driving of the conditioning roll also insures that the rate of conditioning is proportional to the blanket speed. Because the rate of blanket wear is also proportional to the blanket speed, the rate of conditioning and wear are balanced, insuring a consistent blanket surface. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In addition, although specific terms are employed, they are used in a generic and descriptive sense and not for purpose of limitation, the scope of the invention being defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.

A method for continuous conditioning of a rubber blanket such as the type used on compressive shrinkage apparatus is described. The blanket includes an inner bearing surface defining a bearing face and an outer surface defining a web-contacting face. The web-contacting face is contacted under pressure with an abrasive conditioning roll while the blanket is in its regular, web treating operation. The blanket working face can thus be continuously conditioned without the need for lengthy machine stops. In this way, the conventional grinding and cleaning operations can be minimized or eliminated.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing a chilled beverage product, which contains milk and a food acid. The process of the present invention provides a means for making smooth-textured, low viscosity beverage products which contain milk proteins and a food acid, but which exhibit little or no sedimentation. 2. Description of the Prior Art When formulating a flavored drink containing milk proteins at a low pH of between pH 3.5 and 4.5, which contains milk solids, whey proteins are generally favored because they are soluble under acidic conditions. Acidic, flavored drinks with casein proteins are known to be unstable and produce large amounts of casein precipitate. A process and formulation for flavored low pH milk protein-containing beverages, which provides for significantly improved stability of the casein proteins with 97 to 99% stability is herein disclosed. The explanation of the chemistry is below. Milk proteins are generally divided into two classes: casein and whey. Casein is generally recognized as being insoluble under acidic conditions around its isoelectric point of about 4.6. This property of milk proteins is well known and is generally exploited in the manufacturing of cheese. Whey protein is more stable in acid solution and tends to offer less of a precipitation problem. A pH of 4.0 or less is desired for the milk beverage, however, to prevent microbial activity and thus allow for a longer shelf life and to provide a basis for fruit flavor. Where a milk product which contains casein at a pH below 4.6 is desired, additional treatment is required such as the addition of stabilizers or other processes known in the art. Even these known processes have problems of precipitation over time, and require that the product be shaken prior to drinking. Food grade stabilizers such as pectin, propylene glycol alginate, carboxymethylcellulose, xanthan gum, locust bean and combinations thereof have been used to prevent the sedimentation and coagulation of the milk proteins and to improve stability of the beverages. It is reported that even when these food stabilizers are employed, beverage products containing milk proteins and acid or acidic juice at a pH below 4.5 tend to exhibit undesirable sedimentation/precipitation over time. It would be desirable to provide a stable acidic, milk based beverage product which shows enhanced stability with little or no sediment or precipitation. This product should be prepared with conventional processing techniques. The present invention discloses a composition and processing technique for an acidic, milk based beverage with enhanced stability. Known methods for combining acidic fruit juices with milk products have taken several general approaches. Most common is the addition of a stabilizer to the mixture to control precipitation of milk proteins at a lowered pH. U.S. Pat. No. 2,859,115 to Rivoche describes how mixing fruit juice with milk can cause milk proteins to precipitate, because the fruit juice lowers the pH of the beverage. The reference describes overcoming this problem through he use of stabilizers such as pectin. A food powder is mixed with a colloidal stabilizer such as pectin or algin in water, followed by the addition of an alkaline earth salt such as calcium carbonate. A dry acid powder, such as tartaric acid is then added to initiates gel formation. The stabilized mixture is then mixed with milk and stirred at a controlled shear so that the gel is broken up, and a desired viscosity is reached. Similar approaches are employed in U.S. Pat. No. 4,031,264 to Arolski, et al., U.S. Pat. No. 4,046,925 to Igoe, and U.S. Pat. No. 4,078,092 to Nishiyama, all employ similar methods of creating a gel-stabilized mixture, which viscosity is then adjusted by the controlled application of mechanical shear. In Arolski, et al., a fruit mash is mixed with milk and the ensuing coagulation is then controlled by the addition of pectin as a stabilizer. The mixture is stirred and sterilized prior to storage. Igoe involves the formulation of a thickening agent from carboxymethyl cellulose, locust bean gum and xanthan gum in admixture. This stabilizer, with sugar, is added to milk, followed by the addition of fruit juice. In Nishiyama sodium carboxymethyl cellulose is added to the fruit juice first to form a juice composition which can then be added to milk to produce a stable milk product. U.S. Pat. No. 5,648,112 to Yang, et al. describes mixing milk with a food stabilizer under high shear mixing conditions and maintaining a median particle size of less than 0.8 microns to prevent precipitation of milk proteins. Afterward, the pH is reduced to between 3.2 and 4.5 by the addition of food grade acid. U.S. Pat. No. 3,692,532 to Shenkenburg, et al. describes a process whereby a stabilizer having carboxyl groups is added to milk, followed by the addition of fruit juice. According to the process disclosed, sugar and carboxymethyl cellulose are mixed with milk, and sufficient time allowed for the carboxyl groups of the stabilizer to react with the casein. The described reaction is said to occur at temperatures below 90° F., and the resulting mixture is aged, pasteruized and homogenized. The resulting product is stated to be stable at a pH below 5.0. Another approach to creating a stable milk and fruit juice beverage is employed in U.S. Pat. No. 4,520,036 to Rialland, et al., and U.S. Pat. No. 4,676,988 to Efstathiou, et al. These two refernces describe a process whereby milk is passed through a cation exchange resin. The pH of the milk is thus lowered to a value 3.8 (Rialland, et al.) and to between 3.2 and 1.5 (Efstathiou, et al.). Lastly, U.S. Pat. No. 4,416,905 to Lundstedt, et al. describes permitting milk to ferment and achieve a pH in the range between 6.2 to 4.9 and then acidifying the beverage to a pH below 4.7, to produce a better tasting butter milk product SUMMARY OF THE INVENTION It is therefore the object of the present invention to provide a milk protein beverage which contains milk proteins and a food acid, said beverage having a long shelf life and exhibiting little or no sedimentation over time. It is a further object of the present invention to provide a means for making a milk protein beverage which contains milk proteins and a food acid, said beverage having a long shelf life and exhibiting little or no sedimentation over time. It is a further object of the present invention to provide a nutritious and flavorful milk protein beverage which exhibits a smooth texture and a low viscosity, and a means for making same. The present invention relates to a composition and a process for preparing an acidic milk protein based beverage product. The products prepared according to the process of the present invention are stable and do not show sediment or precipitate over time. These products contain from about 0.5% to 5.0% milk proteins and 0.5 to 2.0% of a food stabilizer mixture and a food acid sufficient to lower the pH below 4.5. The present invention comprises concentrated milk protein which is a dry powder which is reconstituted with water to form a solution of milk proteins, specifically casein and whey. The milk protein may be substituted with other milk products, such as whole milk, skim milk, dehydrated milk powder, etc. The process of the present invention comprises, as a first step, mixing the milk proteins with a weak base to elevate the pH. The weak base can be a salt of a weak organic acid, such as sodium citrate, sodium malate, sodium lactate or sodium fumerate. Sodium citrate is the preferred weak base additive. The sodium citrate is added to the concentrated milk protein in sufficient amounts to raise the pH to a range of 7.0 to 8.0. The addition of weak base creates an environment wherein the casein molecules are enhanced in a manner which promotes the association of stabilizer molecules to the surface of the protein. The basic environment also reduces the role of calcium by inhibiting the bridging of calcium with the protein, thus limiting coalescence and sedimentation of the proteins. Stabilizers are then added to the mixture. Stabilizers employed in the invention include pectin, propylene glycol alginate and others, which consist of acidic hydrocolloids. These acidic hydrocolloids are negative charged bodies when present in the basic environment. The negatively charged hydrocolloids adhere to the surface of casein molecules, forming colloidal complexes which are themselves negatively charged. These colloidal complexes resist agglomeration, and thus remain in stable suspension in the mixture, even at low pH and low viscosity. The food stabilizer is added under low shear conditions sufficient to form an intimate mixture. These conditions avoid excessive shear for extended periods of time, which can act to break up the negatively charged colloidal complexes, denature the milk proteins and cause foam. Upon formation of the negatively charged colloidal complexes which effectively stabilize the milk proteins, optional ingredients, such as flavors, colors, sweeteners, vitamin and mineral supplements, microbiological stabilizers, etc. may then be added. The mixture is then homogenized and cooled below 30° C., preferably below 10° C. Acid is then added under low shear conditions to the cooled mixture. A food grade acid such as citric acid is added to bring the pH down to between 3.2 and 4.5. The acid is added in a chilled state, generally below 10° C. Mixing remains under low-shear conditions, so as not to break up the stable colloidal complexes. The final product is then packaged and may stored at room temperature or refrigerated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention relates to a formulation and process for preparing acidic milk based beverage products which develop little of no sediment or precipitation over time. The beverages provide the milk appearance and the flavor of a fruit flavored milk drink at a low viscosity, thus providing a refreshing and rich beverage which is unique. Generally, milk products are formulated at a high pH to avoid sedimentation and precipitation. Milk proteins are known to be unstable at low pH. The stability of the protein must be enhanced with food grade stabilizers or gums, which coat the surface of the protein and inhibit the sedimentation. Mixing of the milk protein with a weak base enhances the structure of the casein proteins and improves the coating of the casein particle with the stabilizing gums. The weak base also can reduce the role of calcium in promoting the coalescence and sedimentation of milk proteins. The stabilizers can be predissolved in water or added directly to the alkaline milk protein base under low shear conditions, to produce the intimate mixture of milk proteins and stabilizers. Optional ingredients are added and the mixture is homogenized to ensure a uniform mix and dispersion. Acid is added under cooled conditions to a pH below 4.5. Particular ingredients and processing steps are described below. A. Process Materials The materials employed in the process of the present invention include milk or concentrated milk protein, a weak base, a food acid and food stabilizer, as well as other optional ingredients. These are described more particularly as follows: 1. Milk The milk proteins used in the process of the present invention may be derived from all forms of milk including, but not limited to, whole milk, skim milk, milk powder, concentrated milk proteins and whey. The milk proteins can be from a dairy ingredient of any form: native, homogenized, concentrated or powder. The amount of milk protein employed in the formulation of the present invention and present in the final beverage products will typically range from about 0.5% to about 5.0% preferably from about 1.0% to about 4.0% which is equivalent to the protein content of native milk. 2. Weak Base The formulation and process employ a weak base to condition the structure of the milk proteins for coating with food stabilizers. The weak base can be salts of weak organic acids like sodium citrate, sodium malate, sodium lactate, or sodium fumarate. Sodium citrate is preferred. Typically, when this is added to the milk proteins, the resulting pH is within a range of 7.0 to 8.0, preferably 7.3-7.7. 3. Food Acid The process of the present invention also employs a food acid. The food acid can include any food grade organic or inorganic acid, for example, citric acid, malic acid, lactic acid, gluconic acid, succinic acid, tartaric acid, phosphoric acid, fumaric acid, and ascorbic acid. Aliphatic hydroxycarboxylic acids (e.g., malic acid, lactic acid, and citric acid) are typicially preferred for use herein. Citric acid is most preferred for use herein. The amount of acid employed is an amount sufficient to adjust the pH of the milk/stabilizer mixture to from about 3.2 to about 4.5, preferably from about 3.5 to about 4.5, most preferably from about 3.8 to about 4.2. Where the acid used is citric acid, typically the citric acid is added in an amount ranging from about 0.3% to about 1.0% by weight of the beverage, preferably between 0.5 to 0.8%. 4. Stabilizer The various food stabilizers which can be employed in the present invention include hydrophilic colloidal stabilizers commonly known in the art such as gum arabic, gelatin, xanthan, locust bean, propylene glycol alginate, and pectin, as well as anionic polymers derived from cellulose (e.g., carboxymethylcellulose), which are water soluble and tolerant of low pH's. A blend of pectin and propylene glycol alginate is typically preferred for use herein. The stabilizer is typically used in an amount ranging from about 0.1% to about 2.0% by weight of the beverage, preferably from about 0.3% to about 1.0%. The amount of stabilizer used is dependent in part on the level of milk solids present in the beverage product. In general, the greater the level of milk solids present in the beverage, the more stabilizer that will be required to stabilize the beverage. The mixture of stabilizers can be adjusted to provide low beverage viscosity and stability of the milk proteins. 5. Other Ingredients Acid dairy beverages usually are formulated to provide a base for fruit flavored products. The fruit flavor can be supplied from fruit juice, fruit concentrates, or flavors, as desired. The formulation of the present invention can also employ a sweetener. The sweetener can include, for example, maltose, sucrose, glucose, fructose, invert sugars and mixtures thereof. These sugars can be incorporated into the beverage products in solid or liquid form, but are typically incorporated as a syrup, more preferably as concentrated syrup such as high fructose corn syrup. For purposes of preparing the beverage products described herein, these optional sweeteners can be provided to some extent by other components of the beverage products, such as by the fruit juice component. Sweeteners are typically employed in the process of the present invention in amounts ranging from about 0.0% to about 15%. Preferred carbohydrate sweeteners for use in the process of the present invention are sucrose, fructose and mixtures thereof. Fructose can be obtained or provided as liquid fructose, high fructose corn syrup, dry fructose or fructose syrup, but is preferably provided as high fructose corn syrup. High fructose corn syrup (HFCS) is commercially available as HFCS-42, HFCS-55 and HFCS-90, which comprise 42%, 55% and 90%, respectively, by weight of the sugar solids therein as fructose. Artificial or noncaloric sweeteners for use in the formulation of the present invention include, for example, saccharin, cyclamates, acetosulfam, L-aspartyl-L-phenyalanine lower alkyl ester sweeteners (e.g., aspartame). A particularly preferred sweetener is aspartame. They may be used as the sole source of sweetness or in combination with caloric sweeteners discussed above. Artificial or noncaloric sweeteners, if used, are typically employed in an amount ranging from about 0.02% to about 1%, preferably from about 0.02% to about 0.10% by weight of the beverage products. The process of the present invention can also optionally employ a preservative. Any food grade preservative can suitably be used in the process of the present invention. Suitable preservatives include sorbic acid, benzoic acid, alkali metal salts thereof, and mixtures thereof. Preferred preservatives include sodium benzoate and potassium sorbate. The preservative is typically present in an amount ranging from about 0.01% to about 0.10% by weight of the beverage product, depending on the method and temperatures of commercial distribution. The formulation of the present invention can also be fortified with various vitamins and minerals. B. Process Steps Milk proteins are added to a solution of a weak base. If the milk protein are in the dry form sufficient time is provided for a uniform dispersion and hydration. This time is highly dependent on the temperature of the solution. At 35° C., two minutes at high shear and 10 minutes at low shear are sufficient to provide a uniform dispersion. The resulting mixture has an elevated pH, which is within a range of 7.0 to 8.0, preferably 7.3 to 7.7. Stabilizers perform best when they are prepared by dispersion and hydration in heated water before the addition to milk proteins. This can be accomplished by many combinations of time, temperature, and shear and depends on the stabilizers employed. For the preferred pectin and propylene glycol alginate mixture, it is desirable to use heated water at a temperature between 55° C. and 75° C. Under high shear conditions, 5 minutes is sufficient to disperse and hydrate the stabilizers. Under low shear conditions, 20 minutes is sufficient to disperse and hydrate the stabilizers. The fully hydrated stabilizers are added to the alkaline milk proteins employing low shear and sufficient time to ensure a complete mixture. Optional ingredients can then be added to the weak base/milk protein/stabilizer mix. If these ingredients are in dry form like sodium benzoate, etc., care should be taken to ensure a complete solution is achieved. The unacidified mix is homogenized under conventional conditions. A two-stage piston homogenizer can be employed at 500/2000 homogenization pressures. The homogenization pressures are not critical to the process and should be sufficient to provide a smooth homogenous mix. Acid can then be added to the homogenized mixture with low shear. It is beneficial to dissolve powdered acids before there addition to the protein mixture. This provides a better mixing of the acid with the protein under low shear conditions. The mix should be cooled before the addition of acid to below 30° C., preferably below 10° C. The acid is similarly cooled to between 1° C. and 30° C. Acid addition rate is not critical to the stability of the mix. EXAMPLES Example 1 Ingredients are used in the following proportions. Ingredients Weight % Water 90.56 Aspartame 0.04 Milk protein 2.35 Sodium citrate 0.34 Vitamin premix 0.15 Sodium benzoate 0.01 Potassium sorbate 0.01 High fructose corm syrup 4.89 Propylene glycol alginate 0.46 Pectin 0.21 Citric acid 0.68 Flavor 0.19 Color 0.12 A tank with high shear is beneficial for completely dispersing and dissolving dry ingredients. Initially, 30 pounds of sodium citrate is dissolved in 3500 pounds of water at 35° C. this is followed by the addition of 208 pounds of dried milk protein concentrate to the sodium citrate solution. The solution is mixed for 2 minutes under high shear, and then is transferred to a larger tank with a low shear mixer for the addition of other ingredients. In a separate vessel, 41 pounds of propylene glycol alginate and 19 pounds of pectin are dissolved in 2000 pounds of water at 65° C. and mixed for 5 minutes. The stabilizers are added to the alkaline milk protein. The remainder of all the other ingredients except the acid are pre-dissolved in 1500 pounds of water and mixed for 2 minutes. The mix is then homogenized in a two-stage piston homogenizer with back pressures of 500/2000 psi. The mix is cooled to less than 5° C. and the chilled acid (below 5° C.) is added to the homogenized mix with a low shear mixer. The resulting product exhibits little or no sediment. Thus, the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.

Acidic milk based beverage products which do not precipitate over time and are physically stable, and a process for preparing these products, are disclosed. These products contain from about 0.5% to 5.0% milk proteins and 0.1 to 2.0% of a food stabilizer and a food acid sufficient to lower the pH below 4.5. The first step of the process involves mixing milk proteins with a food grade weak base to raise the pH above 7.0. Food grade stabilizers are added to the elevated pH mixture of milk proteins and base under low shear conditions. Other ingredients are then added to provide the desired sweetness, flavor, color and microbiological stability. This mixture is homogenized before acidification. A chilled food grade acid is then added at a temperature below 30° c. under low to moderate shear conditions.

CLAIM OF PRIORITY [0001] This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application for CHASSIS STRUCTURE FOR PLASMA DISPLAY MODULE, AND PLASMA DISPLAY MODULE COMPRISING THE SAME, earlier filed in the Korean Intellectual Property Office on Dec. 10, 2004 and there duly assigned Ser. No. 10-2004-0104035. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a chassis structure for a plasma display module and a plasma display module including the plasma display module, and more particularly, to a chassis structure for a plasma display panel that effectively dissipates heat generated by a plasma display panel and improves assembly of the plasma display module, and a plasma display module including the chassis structure. [0004] 2. Description of the Related Art [0005] In general, a plasma display panel is a flat panel display apparatus displaying images using a gas discharge phenomenon. Some of the advantages of the plasma display panel are a large screen with large viewing angle, small thickness, and high image quality. In the plasma display apparatus, a discharge occurs between electrodes due to a Direct Current (DC) or Alternating Current (AC) voltage supplied to the electrodes, and ultraviolet rays generated due to the gas discharge excite a phosphor material to emit visible light. [0006] A plasma display module the plasma display module includes a plasma display panel, a plurality of circuit boards, on which circuits for driving the plasma display panel are mounted, and a chassis supporting the plasma display panel and the circuit boards. [0007] The plasma display panel and the chassis are attached to each other via a dual-adhesive unit attached on a back surface of the plasma display panel, and the dual-adhesive unit is generally a dual-adhesive tape. [0008] A heat dissipation sheet having excellent thermal conductivity is disposed between the plasma display panel and the chassis to dissipate the heat generated during driving the plasma display panel to the chassis. [0009] The chassis is generally formed of metal such as aluminum, and is fabricated in a casting or a press process. [0010] A circuit device is mounted on the circuit board, and the circuit board is mounted on the chassis using a boss and a screw bolt. [0011] However, the chassis of such a plasma display module does not include a heat dissipation structure, and thus, it is difficult to effectively dissipate the heat transmitted to the chassis from the plasma display panel. [0012] In addition, since the base portion of the chassis is formed as a single plate, processes for fabricating the boss having a female screw unit and pressing the boss 0 into the chassis to install the boss are required so as to fix the circuit boards onto the chassis. Therefore, the number of processes for assembling such a plasma display module is increased, and thus, fabrication of the plasma display module is expensive and time-consuming. SUMMARY OF THE INVENTION [0013] The present invention provides a chassis structure for plasma display module, which is capable of effectively dissipating heat generated by a plasma display panel and improving assembly of the plasma display module, and a plasma display module including the chassis structure. [0014] According to one aspect of the present invention, a chassis structure for a plasma display module is provided, the chassis comprising: a front plate; a back plate separated from the front plate; and a heat dissipation member arranged between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plates. [0015] The heat dissipation member preferably comprises a serpentine cross-section. The heat dissipation member alternatively preferably comprises a convex-concave cross-section. The heat dissipation member preferably comprises a heat conductive material. [0016] According to another aspect of the present invention, a plasma display module is provided comprising: a plasma display panel; at least one circuit board adapted to drive the plasma display panel; a front plate adapted to support the plasma display panel; a back plate adapted to support the at least one circuit board and separated from the front plate; and a heat dissipation member arranged between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plate. [0017] The plasma display module preferably further comprises a heat dissipation sheet arranged between the plasma display panel and the front plate. [0018] The heat dissipation member preferably comprises a serpentine cross-section. The heat dissipation member alternatively preferably comprises a convex-concave cross-section. The heat dissipation member preferably comprises a heat conductive material. [0019] The back plate preferably comprises an aperture adapted to fix the circuit board thereon. [0020] The plasma display module preferably further comprise a connection unit adapted to fix the at least one circuit board on the back plate, wherein a first end of the connection unit is arranged on the at least one circuit board, and wherein a second end of the connection unit passes through the aperture to be arranged in a space between the front and back plates. [0021] The second end of the connection unit preferably comprises a tapered wing. The connection unit preferably comprises a synthetic resin. BRIEF DESCRIPTION OF THE DRAWINGS [0022] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: [0023] FIG. 1 is a perspective view of a plasma display module; [0024] FIG. 2 is a cross-sectional view of the plasma display module taken along line II-II of FIG. 1 ; [0025] FIG. 3 is a cross-sectional view of a chassis structure of a plasma display module according to a first embodiment of the present invention; [0026] FIG. 4 is a perspective view of a heat dissipation member according to the first embodiment of the present invention; [0027] FIG. 5 is a cross-sectional view of a modified example of chassis structure of the plasma display module according to the first embodiment of the present invention; [0028] FIG. 6 is a perspective view of a modified example of the heat dissipation member according to the first embodiment of the present invention; [0029] FIG. 7 is a perspective view of another modified example of the heat dissipation member according to the first embodiment of the present invention; and [0030] FIG. 8 is a partial cross-sectional view of a chassis structure of a plasma display module according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0031] FIG. 1 is a perspective view of a plasma display module in a plasma display apparatus, and FIG. 2 is a cross-sectional view of the plasma display module taken along line II-II of FIG. 1 . [0032] Referring to FIG. 1 , the plasma display module 100 includes a plasma display panel 100 , a plurality of circuit boards 120 , on which circuits for driving the plasma display panel 110 are mounted, and a chassis 130 supporting the plasma display panel 110 and the circuit boards 120 . [0033] The plasma display panel 110 and the chassis 130 are attached to each other via a dual-adhesive unit 140 affixed to a back surface of the plasma display panel 110 , and the dual-adhesive unit 140 is generally a dual-adhesive tape. [0034] A heat dissipation sheet 150 having excellent thermal conductivity is disposed between the plasma display panel 110 and the chassis 130 to transmit the heat generated during the driving of the plasma display panel 110 to the chassis 130 . [0035] The chassis 130 is generally formed of metal such as aluminum, and is fabricated by casting or pressing. [0036] A circuit device is mounted on the circuit board 120 , and the circuit board 120 is mounted on the chassis 130 using a boss 160 and a screw bolt 170 . [0037] However, the chassis 130 of the plasma display module 100 does not include a heat dissipation structure, and thus, it is difficult to effectively dissipate the heat transmitted to the chassis 130 from the plasma display panel 110 . [0038] In addition, since the base portion of the chassis 130 is formed as a single plate, processes for fabricating the boss 160 having a female screw unit and pressing the boss 160 into the chassis 130 to install the boss 160 are required so as to fix the circuit boards 120 onto the chassis 130 . Therefore, the number of processes for assembling the plasma display module is increased, and thus, fabrication of this plasma display module is expensive and time-consuming. [0039] Referring to FIGS. 3 and 4 , a plasma display module 200 according to a first embodiment of the present invention includes a plasma display panel 210 , a plurality of circuit boards 220 , on which circuits for driving the plasma display panel 210 are mounted, and a chassis 230 supporting the plasma display panel 210 and the circuit boards 220 . [0040] The chassis 230 includes a front plate 231 , a back plate 232 , and a heat dissipation member 233 . [0041] The plasma display panel 210 and the front plate 231 are attached to each other by a dual-adhesive unit 240 affixed to a back surface of the plasma display panel 210 , and a circuit device 221 is disposed on the circuit board 220 . [0042] A heat dissipation sheet 250 is disposed between the plasma display panel 210 and the front plate 231 to transmit heat generated by the plasma display panel 210 to the front plate 231 . [0043] The back plate 232 is separated a predetermined distance from the front plate 231 , and the predetermined distance can be determined by a designer of the module in consideration of the heat dissipating performance and thickness of the plasma display module 200 . [0044] In FIGS. 4 and 5 , the heat dissipation member 233 is located between the front plate 231 and the back plate 232 , and has a serpentine cross-section. In addition, the heat dissipation member 233 is formed of a thermally conductive material, that is, generally metal. [0045] Ridge portions 234 of the heat dissipation member 233 contact the front plate 231 and the back plate 232 . In addition, valley portions 235 at the opposing side of the ridge portions 234 , the front plate 231 , and the back plate 232 form air flow paths 280 . Therefore, some of the heat transmitted to the heat dissipation member 233 is transmitted to the air flowing in the air flow paths 280 to be dissipated, and the residual heat transmitted to the heat dissipation member 233 is transmitted to the back plate 232 and dissipated. [0046] It is desirable that the heat dissipation member 233 bent with a constant curvature is disposed between the front plate 231 and the back plate 232 , and then, these elements are brazed together. [0047] The circuit board 220 is mounted on the back plate 232 using a boss 260 and a screw bolt 270 . [0048] The operation of the chassis structure according to the first embodiment of the present invention is as follows. [0049] When the plasma display module 200 is driven, a lot of heat is generated by the plasma display panel 210 . The generated heat is transmitted to the front plate 231 after passing through the heat dissipation sheet 250 . [0050] The heat transmitted to the front plate 231 is transmitted to the heat dissipation member 233 . Since the heat dissipation member 233 has a serpentine cross-section, a surface area of the heat dissipation member 233 is large, and a plurality of air flow paths 280 are formed, and thus, a large amount of the heat transmitted to the heat dissipation sheet 233 is dissipated out of the chassis 230 . [0051] That is, since the edges of the chassis 230 are open, external air can be induced and discharged into/out of the chassis 230 . The air induced in the chassis 230 absorbs the heat while contacting the heat dissipation member 233 , and then, is exhausted out of the chassis 230 . Thus, a large amount of the heat transmitted to the heat dissipation member 233 can be exhausted effectively out of the chassis 230 by the air induced in the chassis 230 . [0052] In addition, the residual heat transmitted to the heat dissipation member 233 is transmitted to the back plate 232 and dissipated. [0053] That is, according to the first embodiment of the present invention, the chassis 230 includes the front plate 231 , the back plate 232 , and the heat dissipation member 233 , and the heat generated by the plasma display panel 210 is effectively dissipated by the heat dissipation member 233 . [0054] Hereinafter, a modified example of the above chassis structure according to the first embodiment of the present invention is described with reference to FIGS. 5-7 , and different elements from those of the above example are described. [0055] FIG. 5 is a cross-sectional view of a modified example of chassis structure of the plasma display module according to the first embodiment of the present invention, and FIG. 6 is a perspective view of a modified example of the heat dissipation member according to the first embodiment of the present invention. [0056] The plasma display module 300 includes a plasma display panel 310 , circuit boards 320 , and a chassis 330 . [0057] The chassis 330 includes a front plate 331 , aback plate 332 , and a heat dissipation member 333 , and the plasma display panel 310 is supported at the front plate 331 using a dual-adhesive unit 340 . [0058] Compared to the above first embodiment, the modified example of the first embodiment has a heat dissipation member 333 of a different shape than that of the heat dissipation member 233 of FIGS. 3-4 . [0059] That is, unlike the heat dissipation member 233 having the serpentine cross-section, the modified heat dissipation member 333 has a convex-concave cross-section. [0060] The heat dissipation member 333 is formed of a thermally conductive material. Ridge portions 334 of the heat dissipation member 333 contact the front plate 331 and the back plate 332 . Valley portions 335 at the opposing side of the ridge portions 334 , the front plate 331 , and the back plate 332 form air flow paths 380 . [0061] Therefore, the heat generated by the plasma display panel 310 is transmitted to the front plate 331 through the heat dissipation sheet 350 . A large amount of the heat transmitted to the front plate 331 is transmitted to the heat dissipation member 333 , and some of the heat transmitted to the heat dissipation member 333 is absorbed by the air flowing in the air flow paths 380 to be dissipated, and the residual heat transmitted to the heat dissipation member 333 is transmitted to the back plate 332 and dissipated. [0062] FIG. 7 is a perspective view of another modified example of the heat dissipation member according to the first embodiment of the present invention. The heat dissipation member 433 is formed by slightly changing the shape of the heat dissipation member 333 of FIG. 6 . That is, connections between ridge portions 434 and valley portions 435 are slanted. [0063] The elements of the modified examples of the heat dissipation member perform the same functions as those of the elements in the dissipation member of the first embodiment. However, the heat dissipation members 333 and 433 of FIGS. 5-7 have larger ridge portions 334 and 434 contacting the front and back plates 231 and 232 than those of the heat dissipation member 233 of the first embodiment. Therefore, the heat dissipation members 333 and 433 have some different characteristics from those of the heat dissipation member 233 in that the heat from the plasma display panel can be easily transmitted to the heat dissipation members 333 and 433 and that the heat dissipation members 333 and 433 have relatively smaller heat dissipation surface area. [0064] Hereinafter, a plasma display module according to a second embodiment of the present invention is described with reference to FIG. 8 . [0065] The plasma display module 500 according to the second embodiment of the present invention includes a plasma display panel 510 , a plurality of circuit boards 520 , on which circuits driving the plasma display panel 510 are mounted, and a chassis 530 supporting the plasma display panel 510 and the circuit boards 520 . [0066] The chassis 530 includes a front plate 531 , a back plate 532 , and a heat dissipation member 533 . [0067] The plasma display panel 510 and the front plate 531 of the chassis 530 are attached to each other by a dual-adhesive unit 540 affixed to a back surface of the plasma display panel 510 . [0068] A heat dissipation sheet 550 is disposed between the front plate 531 and the plasma display panel 510 to transmit the heat generated by the plasma display panel 510 to the front plate 531 . [0069] The back plate 532 is separated a predetermined distance from the front plate 531 , and a heat dissipation member 533 is located between the front plate 531 and the back plate 532 . In addition, air flow paths 580 are formed by the front plate 531 , the back plate 532 , and the heat dissipation member 533 . [0070] The heat dissipation member 533 has the same structure and function as those of the heat dissipation member 433 of the previous embodiment. [0071] That is, the heat generated when the plasma display panel 510 is driven is transmitted to the heat dissipation member 533 after passing through the heat dissipation sheet 550 , and some of the heat transmitted to the heat dissipation member 533 is absorbed by the air flowing in the air flow paths 580 and dissipated, and the residual heat is transmitted to the back plate 532 and dissipated. [0072] In addition, the back plate 532 includes holes 590 for fixing the circuit boards 520 , and the circuit boards 520 are fixed on the back plate 532 by connection units 570 . [0073] The connection unit 570 is formed of synthetic resin. In addition, a first end 571 of the connection unit 570 is mounted on the circuit board 520 , and a second end 572 of the connection unit 570 passes through the hole 590 formed on the back plate 532 and is located in the space between the front plate 531 and the back plate 532 . [0074] The second end 572 of the connection unit 570 includes a wing part 573 having tapered shape, and thus, it can be only inserted into the hole 590 formed on the back plate 532 in one direction, and when the second end 572 of the connection unit 570 is inserted into the hole 590 , the wing part 573 is bent inward. [0075] After the wing part 573 of the connection unit 570 passes through the hole 590 , the wing part 573 is recovered to the original status by an elastic force, and thus, the second end 572 of the connection unit 570 is located between the front plate 531 and the back plate 532 . Therefore, the second end 572 of the connection unit 570 and a suspending step 574 can fix the circuit board 520 onto the back plate 532 . [0076] In addition, referring to FIG. 8 , it is desirable that the end 572 of the connection unit 570 is located toward the valley portion of the heat dissipation member 533 avoiding from the ridge portion of the heat dissipation member 533 . [0077] Therefore, in order to assemble the plasma display module 500 according to the second embodiment of the present invention, the circuit board 520 can be firmly fixed on the back plate 532 simply by mounting the first end 571 of the connection unit 570 on the circuit board 520 and pushing the second end 572 of the connection unit 570 into the hole 590 of the back plate 532 . Therefore, a process of forming the boss on the chassis for fixing the circuit board on the chassis is not necessary. [0078] The assembling way of the plasma display module 500 according to the second embodiment of the present invention cannot be applied to a conventional plasma display module, in which the chassis is formed as a single plate, since the second end 572 of the connection unit 570 collides with the plasma display panel in the conventional plasma display module even if the connection unit 570 is inserted after forming the hole on the chassis. Therefore, the connection unit 570 cannot be fixed on the chassis of the conventional plasma display module. That is, since the chassis of the conventional plasma display module is formed as a single plate, there is no space to receive the second end 572 of the connection unit 570 , and thus, the connection unit 570 cannot be fixed on the chassis in the conventional plasma display module. [0079] According to the plasma display module of the second embodiment of the present invention, since the chassis 530 includes the front plate 531 , the back plate 532 , and the heat dissipation member 533 , the heat dissipation member 533 can effectively dissipate the heat transmitted to the front plate 531 . In addition, the circuit boards 520 can be mounted on the back plate 532 in easy and effective way by using the space between the front plate 531 and the back plate 532 and the connection unit 570 . [0080] As described above, according to the present invention, the chassis includes the front plate, the back plate, and the heat dissipation member, and thus, the heat generated by the plasma display panel can be dissipated using the heat dissipation member. [0081] In addition, since the front plate and the back plate are separated a predetermined distance from each other, the circuit board can be mounted on the back plate in easy and effective way using the connection unit, and the assembling convenience of the plasma display module can be improved. Therefore, the production time and manufacturing costs can be reduced. [0082] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various modifications in form and detail can be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

A chassis structure for a plasma display module, and a plasma display module including the chassis structure effectively dissipate heat generated by a plasma display panel and improve assembly of the plasma display module. The chassis base includes: a front plate; a back plate separated from the front plate; and a heat dissipation member disposed between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plate.

FIELD OF THE INVENTION AND RELATED ART [0001] The present invention relates to a charging apparatus for charging a photosensitive member, in particular, a charging apparatus which is employed by an electrophotographic image forming apparatus, for example, a copying machine, a printer, a fax, a multifunction apparatus capable of two or more of the functions of the preceding apparatuses, etc. [0002] There have been known various methods for charging the surface of the photosensitive member of an electrophotographic image forming apparatus. Among these charging methods, the charging method which applies oscillatory voltage made up of DC and AC voltages is superior in terms of the uniformity of charge. Hereafter, the methods for charging a photosensitive member by applying oscillatory voltage to a charging member will be referred to as “AC charging method”. [0003] However, the AC charging method has its own problems. One of the problems is as follows: The AC charging method is greater in the amount of the electrical discharge to a photosensitive member than the DC charging method. Therefore, the AC charging method tends to promote the deterioration, for example, shaving, of a photosensitive member. Further, the employment of the AC charging method sometimes resulted in the formation of abnormal images, for example, images suffering from the appearance of flowing water, because of the byproducts of electrical discharge, in an operational environment in which both temperature and humidity were high. [0004] In order to improve the AC charging method in terms of this problem, it is necessary to minimize in amount the electrical discharge which alternately occurs toward positive and negative sides. In order to minimize in amount the electrical discharge, it is necessary to minimize the amount of voltage necessary to properly charge a photosensitive member. [0005] In reality, however, the relation between voltage and the amount of the electrical discharge caused by the voltage is not always the same. That is, it is affected by the changes in the thickness of the photosensitive layer and inductive layer of a photosensitive member, changes in a charging member, changes of the air attributable to environmental changes, etc. For example, in an environment in which both temperature and humidity are low (L/L), the materials of a photosensitive member dry, causing thereby the photosensitive member to increase in the resistance value, which in turn makes it difficult for electrical discharge to occur. Thus, in order to uniformly charge a photosensitive member, it is necessary for the peak-to-peak voltage to be higher than a certain value. However, keeping the peak-to-peak voltage higher than a certain value creates the following problem. That is, in a case where a charging operation is carried out in a high temperature-high humidity environment (H/H), with the charge voltage set so that its peak-to-peak voltage is higher than the preset value for ensuring a photosensitive member to be uniformly charged under the low temperature-low humidity (L/L) environment, the charging member causes more electrical discharge than necessary to properly charge the photosensitive member, because in the H/H environment, the materials for a photosensitive member and charging member absorb humidity, and therefore decreases in electrical resistance value. The increase in the amount of the electrical discharge causes various problems. For example, it causes an image forming apparatus to yield images which suffer from the appearance of flowing water, images which appear blurry, and the like. Further, it causes toner particles to melt and adhere to each other. Also, it reduces the service life of a photosensitive member, because it accelerates the deterioration of the peripheral surface of a photosensitive drum, accelerating thereby the shaving of the peripheral surface. [0006] As the methods for preventing the electrical discharge from being made to fluctuate in amount by the environmental changes, there have been proposed the “AC voltage stabilizing controlling method” that keeps constant in value the AC voltage applied to a charge roller, and also, “AC current stabilizing control method” that controls in value the AC current which flows as the AC voltage is applied to a charging member. The AC current stabilizing control method makes it possible to control a charging apparatus so that in the L/L environment, that is, the environment in which the materials increase in electrical resistance, the AC charge voltage increases in the peak-to-peak voltage value, whereas in the H/H environment, that is, the environment in which the materials decrease in electrical resistance, the AC charge voltage decreases in the peak-to-peak voltage. Therefore, the AC current stabilizing control method can more effectively prevent the fluctuation in the amount of the electrical discharge than the AC voltage stabilizing control method. [0007] However, from the standpoint of further prolonging the service life of a photosensitive member, even the AC current stabilizing control method cannot be said to be perfect, because it cannot completely prevent the fluctuation in the amount of electrical discharge, which is attributable to the nonuniformity in properties among charging members, which is attributable to manufacturing processes; charge roller contaminations; change in the electrostatic capacity of a photosensitive member; nonuniformity in properties among high voltage generating apparatuses for the main assembly of an image forming apparatus; etc. Thus, in order to perfectly prevent the electrical discharge between a charging member and a photosensitive member, from fluctuation in amount, various measures have to be taken to improve charging member manufacturing processes so that all charging members will be uniform in properties, to ensure that the operational environment for an image forming apparatus does not change in temperature and humidity, and to come up with a means for preventing a high voltage generating apparatus from fluctuating in output, which results in substantial cost increase. [0008] Thus, there have been proposed various methods for uniformly charging a photosensitive member, which were intended to prevent such problems as the deterioration of a photosensitive member, thermal adhesion of toner particles to each other, formation of images with an appearance of flowing water, etc., by keeping the electrical discharge constant in amount by preventing the occurrence of excessive amount of electrical discharge, regardless of the nonuniformity in electrical resistance value among charging members, which are attributable to charging member manufacturing processes, and the change in electrical resistance value of a charging member, which is attributable to the changes in environmental factors. [0009] For example, disclosed in Japanese Laid-open Patent Application 2000-201921 is the following method for determining the properties of the voltage to be applied to a charging means and the properties of the current to be flowed by the charging means. That is, a DC voltage is applied to a charging member, and discharge start voltage Vth is obtained. Then, a function between AC voltage and AC current is obtained at a point in the non-discharge range, that is, DC voltage range in which voltage is no higher than the charge start voltage Vh, and another function between AC voltage and AC current is obtained at a point in the discharge range, that is, the DC voltage range in which voltage is higher than the charge start voltage Vh. Then, the discharge current amount is obtained as the difference between the two functions, and the charging means is controlled so that the obtained discharge current amount remains stable. [0010] Disclosed in Japanese Laid-open Patent Application 2004-333789 is the following method for obtaining the smallest amount of discharge necessary to uniformly charge a photosensitive member. That is, while applying AC voltage, the amount of DC current is measured to find the DC current saturation point in the AC electric field. Then, the AC voltage value which corresponds to this DC current saturation point is multiplied by a preset ratio, and the product is used as the value for the charge bias for an actual image forming operation. [0011] However, in the case of the above-described method disclosed in Japanese Laid-open Patent Application 2001-201921, unless the discharge start voltage Vth obtained by applying the DC voltage is accurately known, it is impossible to precisely separate the discharge range from the non-discharge range. [0012] FIG. 18 is a graph which shows the relationship between the DC voltage applied to a charging member to charge a photosensitive member A, and the measured amount of surface potential of the photosensitive member A, and the relationship between the DC voltage applied to the charging member to charge a photosensitive member B, which is different in material from the photosensitive member A, and the measured amount of surface potential of the photosensitive member B. [0013] The following is evident from FIG. 18 . That is, in the case of the photosensitive member A, as the DC voltage is increased, the surface potential remained at 0 V until the voltage reached a certain value. Then, from this point on, the surface potential of the photosensitive member A linearly increased. This value is the value of the Vth. On the other hand, in the case of the photosensitive member B, the surface potential gradually increases from the point where the DC voltage was 0 V, although the amount of increase was very small. Then, after the Dc voltage reached a certain point, the surface potential of the photosensitive member B linearly increased. [0014] The difference in properties between the two photosensitive members A and B is affected by the electrical resistance, capacity, and materials of the photosensitive members A and B, the electrical resistance, capacity, and materials of the charging member, and the environmental factors. Thus, there occur many situations in which the discharge start point Vth cannot be accurately obtained when DC voltage is applied. [0015] Further, the method used by the apparatus disclosed in Japanese Laid-open Patent Application 2001-201921 is characterized in that the functions between the discharge range and non-discharge range are linear, and the difference between the two functions is calculated. However, the relationship between the peak-to-peak voltage and AC current is not linear at all. That is, referring to FIG. 19 , as the peak-to-peak voltage is continuously increased beyond a certain value, the AC current tends to increase with accelerated rates compared to the rate with which the peak-to-peak voltage is increased. It became evident from the results of intensive studies that this phenomenon occurs because the discharge nip between the charging member and photosensitive member increases in size as the AC voltage is increased in peak-to-peak voltage. [0016] Thus, in order to compare the discharge current amount in the discharge range and that in the non-discharge range in terms of linear function, the value of the peak-to-peak voltage of the AC voltage to obtain the amount of discharge current in the discharge range is desired to be as close as possible the value of the peak-to-peak voltage of the discharge start voltage. Further, using such a value for the peak-to-peak voltage makes it possible to accurately and easily obtain the desired amount of discharge current. Japanese Laid-open Application No. 2001-201921 does not referred to this matter. [0017] FIG. 20 is a graph which shows the relationship between peak-to-peak voltage and AC current, which was obtained, with the use of a combination of a charging member and a photosensitive member, at the time when recording medium began to be conveyed, and that obtained with the use of the same combination of a charging member and a photosensitive member, after a certain number of recording mediums were conveyed, in the case where the discharge start point was accurately found using the method disclosed in Japanese Laid-open Patent Application No. 2004-333789. [0018] In the case where the value of the peak-to-peak voltage at the discharge start point is multiplied with a preset ratio of 1.15, the amount of discharge current was substantially greater after a certain number of recording mediums were conveyed, and therefore the rate of the AC current had substantially increased, than at the time when the recording medium conveyance was started. The relationship between AC voltage and AC current in terms of the rate with which they change is affected by various factors, such as the change in the film thickness of a photosensitive member, change in the operational environment of an image forming apparatus, cumulative image formation count, etc. Therefore, it is difficult to take all of these factors into consideration in order to accurately determine the relationship between the AC voltage and AC current. Therefore, it is difficult to maintain an accurate amount of discharge current with the use of the method which multiplies the peak-to-peak voltage at the discharge start point by a preset ratio. SUMMARY OF THE INVENTION [0019] One of the primary objects of the present invention is to provide a charging apparatus which is significantly smaller than a conventional charging apparatus, in the amount of the damages to which a photosensitive member is subjected when the photosensitive member is charged by a charging apparatus. [0020] According to an aspect of the present invention, there is provided a charging apparatus, comprising a charging device for electrically charging a photosensitive member; a bias applying device for applying to said charging member a charging bias voltage comprising a DC voltage component and a AC voltage component, wherein said bias applying device effect a constant voltage control with a constant AC component of the charging bias voltage; a AC detector for detecting a AC detected current when said charging member is supplied with a test bias voltage; a DC detector for detecting a DC detected current when said charging member is supplied with the test bias voltage; and a controller for controlling a charging bias voltage to be applied to said charging member; wherein said control means determines a peak-to-peak voltage Vo when a change rate of detected DC current provided by sequentially applying the test bias voltages having different peak-to-peak voltages in order of increasing or decreasing peak-to-peak voltage becomes not more than a predetermined level, and said control means sets a peak-to-peak voltage of the charging bias voltage on the basis of a detected AC current when a peak-to-peak voltage Vp larger than the peak-to-peak voltage Vo and a detected AC current when a peak-to-peak voltage Vq not larger than the peak-to-peak voltage Vo. [0021] According to another aspect of the present invention, there is provided a charging apparatus, comprising a charging device for electrically charging a photosensitive member; a bias applying device for applying to said charging member a charging bias voltage comprising a DC voltage component and a AC voltage component, wherein said bias applying device effects a constant current control with a constant AC component of the charging bias voltage; a AC detector for detecting a peak-to-peak voltage of the AC component when a test bias voltage is applied to said charging member; a AC detector for detecting a AC detected current when said charging member is supplied with the test bias voltage; and a controller for controlling a charging bias voltage to be applied to said charging member; wherein said control means determines an AC current Io when a change rate of detected DC current provided by sequentially applying the test bias voltages having different AC currents in order of increasing or decreasing AC current becomes not more than a predetermined level, and said control means sets an AC current of the charging bias voltage on the basis of a detected peak-to-peak voltage when an AC current Ip larger than the AC current Io and a detected peak-to-peak voltage when an AC current Iq not larger than the AC current Io. [0022] These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0023] FIG. 1 is a schematic sectional view of the image forming apparatus in the first preferred embodiment of the present invention, and shows the general structure of the apparatus. [0024] FIG. 2 is a schematic sectional view of the surface layers of the photosensitive drum, and charge roller, in the first embodiment, and shows their laminar structures. [0025] FIG. 3 is a diagram of the operational sequence of the image forming apparatus. [0026] FIG. 4 is a block diagram of the charge bias applying system. [0027] FIG. 5 is a graph showing the results of the measurements of the discharge current amount. [0028] FIG. 6 is a flowchart for describing the charge controlling method in the first preferred embodiment of the present invention. [0029] FIG. 7 is a graph for describing the relationship between peak-to-peak voltage and DC current. [0030] FIG. 8 is a graph for describing the relationship between peak-to-peak voltage and the potential level of the charged object. [0031] FIG. 9 is a drawing for describing the relationship between the peak-to-peak voltage and AC, regarding the charge controlling method in the first embodiment of the present invention. [0032] FIG. 10 is a flowchart for describing the charge controlling method in the second preferred embodiment of the present invention. [0033] FIG. 11 is a drawing for describing the relationship between the peak-to-peak voltage and AC current, regarding the charge controlling method in the second embodiment of the present invention. [0034] FIG. 12 is a flowchart for describing the charge controlling method in the third preferred embodiment of the present invention. [0035] FIG. 13 is a graph showing the relationship between the AC current and DC current. [0036] FIG. 14 is a drawing for describing the relationship between the AC current and the potential level of the charged object. [0037] FIG. 15 is a drawing for describing the relationship between the peak-to-peak voltage and AC current, regarding the charge controlling method in the third embodiment of the present invention. [0038] FIG. 16 is a flowchart for describing the charge controlling method in the fourth preferred embodiment of the present invention. [0039] FIG. 17 is a drawing for describing the relationship between the peak-to-peak voltage and Ac current, regarding the charge controlling method in the fourth embodiment of the present invention. [0040] FIG. 18 is a drawing for describing the relationship between the DC voltage and surface potential of the charged object, regarding one of the conventional DC charging methods. [0041] FIG. 19 is a graph which roughly shows the relationship between the measured amount of discharge current and peak-to-peak voltage, regarding the conventional charging apparatus (charge controlling method). [0042] FIG. 20 is a drawing which describes the relationship between the peak-to-peak voltage and AC current, regarding the conventional charging apparatus (charge controlling method). [0043] FIG. 21 is a drawing for the comparison between the computation in the conventional discharge current controlling method and that in one of the preferred embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0044] Hereinafter, a charging apparatus in accordance with the present invention, and an image forming apparatus which has the charging apparatus in accordance with the present invention, will be described in more detail with reference to the appended drawings. Embodiment 1 [0045] FIG. 1 is a vertical sectional view of the image forming apparatus in the first preferred embodiment of the present invention, and shows the general structure of the apparatus. The image forming apparatus 100 in this embodiment is a laser beam printer which uses one of the electrophotographic processes of the transfer type. The laser beam printer uses a charging method of the contact type, and a developing method of the reversal type. The largest sheet of recording medium usable with (passable through) this printer is A3 in size. [0046] The image forming apparatus 100 in this embodiment is provided with an electrophotographic photosensitive member 1 , as an image bearing member, which is in the form of a drum, (which hereafter may be referred to as “photosensitive drum”). The image forming apparatus 100 is also provided with a charge roller 2 , a developing apparatus 4 , a transfer roller 5 , and a cleaning apparatus 7 , which are disposed in the adjacencies of the peripheral surface of the photosensitive drum 1 , listing from the upstream side in terms of the rotational direction R 1 (counterclockwise direction) of the photosensitive drum 1 . The charge roller 2 is a part of a charging apparatus 200 . The transfer roller 5 is a charging member of the contact type. The image forming apparatus 100 is also provided with an exposing apparatus 3 , which is disposed above the roughly mid point between the developing apparatus 4 and charge roller 2 . Further, the image forming apparatus 100 is provided with a fixing apparatus 6 , which is on the downstream side of the transfer portion d (which is interface between photosensitive drum 1 and transfer roller 5 ), in terms of the recording medium conveyance direction. [0047] The photosensitive drum 1 is an organic photosensitive member (OPC). It is 30 mm in external diameter, and is negatively charged. It is rotationally driven by a driving apparatus (unshown) at a process speed (peripheral velocity) of 210 mm in the direction (counterclockwise direction) indicated by an arrow mark R 1 . Referring to FIG. 2 , the photosensitive drum 1 is made up of an aluminum cylinder 1 a (electrically conductive substrate); an undercoat layer 1 b coated on the peripheral surface of the photosensitive drum 1 to prevent the optical interference and to improve the adhesion of the upper layer to the aluminum cylinder 1 a; an optical charge generation layer 1 c; and a charge transfer layer 1 d. The three layers are coated in layers in the listed order on the aluminum cylinder 1 a. [0048] The charge roller 2 is rotationally supported at the lengthwise end portions of its metallic core 2 a, by a pair of bearings (unshown), one for one. It is kept pressed toward the center of the photosensitive drum 1 by a pair of compression springs 2 e so that a preset amount of contact pressure is maintained between the peripheral surface of the photosensitive drum 1 and peripheral surface of the charge roller 2 . As the photosensitive drum 1 is rotationally driven, the charge roller 2 is rotated by the rotation of the photosensitive drum 1 in the clockwise direction indicated by an arrow mark R 2 . The contact nip formed between the photosensitive drum 1 and charge roller 2 is the charging portion a (charging nip). [0049] As a charge bias voltage, which is under a specific condition, is applied to the metallic core 2 a of the charge roller 2 from an electrical power source S 1 , the peripheral surface of the photosensitive drum 1 is charged to preset polarity and potential level by the charge roller 2 , which is in contact with the photosensitive drum 1 . In this embodiment, the charge bias voltage applied to the charge roller 2 is an oscillatory voltage which is a combination of a DC voltage (Vdc) and an alternating voltage (AC), more specifically, −1,500 V of DC voltage, and an AC voltage which is 2 kHz in frequency. As a result, the peripheral surface of the photosensitive drum 1 is uniformly charged to −500 V (dark voltage level Vd) by the charge roller 2 , which is in contact with the peripheral surface of the photosensitive drum 1 . [0050] The charge roller 2 is 320 mm in length. It has the metallic core 2 a (substrate), and three layers 2 b (bottom layer), 2 c (intermediary layer), and 2 d (surface layer), which cover the metallic core 2 a in the listed order. The bottom layer 2 b is formed of foamed sponge, and is for reducing the charging noises. The surface layer 2 d is a protective layer provided to prevent leak even if the photosensitive drum 1 has a defect, such as a pin hole or the like. [0051] More concretely, the specifications of the charge roller 2 in this embodiment are as follows: [0052] metallic core 2 a: stainless steel rod with a diameter of 6 mm; [0053] bottom layer 2 b: foamed rubber (NBR) in which carbon particles has been dispersed, and which is 0.5 g/cm 2 in specific gravity, 10 2 −10 9 Ω.cm in volume resistivity; and 3.0 mm in thickness [0054] intermediary layer 2 c: fluorinated “Torejin” resin in which tin oxide and carbon particles have been dispersed, and which is 10 7 −10 10 Ω.cm in volume resistivity, 1.5 μm in surface roughness (10 point average surface roughness Ra in JIS), and 10 μm in thickness [0055] This embodiment employs such a charging method that charges a photosensitive member by placing a charge roller in contact with the photosensitive drum. However, this is not mandatory. That is, for example, such a method that charges a photosensitive member with the presence of a gap (several tens of micrometers) between a charge roller and a photosensitive member may be employed. In the latter case, all that is necessary is that the gap size falls within the discharge-possible range, which is determined by the gap voltage and the air density (Paschen's law). As long as this requirement is met, the latter can charge a photosensitive drum just as well as the charging method used in this embodiment. [0056] The exposing apparatus 3 in this embodiment is a laser beam scanner which uses a semiconductor laser. The laser beam scanner 3 exposes a portion (point) of the uniformly charged portion of the peripheral surface of the photosensitive drum 1 , at the exposure position (point) b, by outputting a beam of laser light L in a manner to scan the peripheral surface of the photosensitive drum 1 while modulating the beam with the image signals inputted from an unshown host apparatus, such as an image reader or the like. As a given portion (point) of the peripheral surface of the photosensitive drum 1 is exposed to the beam of laser light, this portion (point) reduces in potential. Thus, as the peripheral surface of the photosensitive drum 1 is scanned by the beam of laser light L, an electrostatic latent image, which reflects the image information with which the beam of laser light L is modulated, is formed line by line. [0057] The developing apparatus 4 in this embodiment is such a developing apparatus that develops in reverse the electrostatic latent image with the use of a developing method which uses two-component magnetic brush. It reversely develops the electrostatic latent image on the photosensitive drum 1 ; it deposit toner on the exposed (light) portions (points) of the peripheral surface of the photosensitive drum 1 . That is, the developing apparatus 4 makes the electrostatic latent image visible by supplying the electrostatic latent image with toner. [0058] This developing apparatus 4 is provided with a nonmagnetic development sleeve 4 b, which is rotatably disposed in the developing means container 4 a so that the development sleeve 4 b is exposed through an opening of the container 4 a. The developer 4 e (toner) in the developing means container 4 a is coated in a thin layer on the peripheral surface of the development sleeve 4 b. The coated layer of developer 4 e is conveyed by the rotation of the development sleeve 4 b to the development portion c where the distance between the peripheral surface of the development sleeve 4 b and the peripheral surface of the photosensitive drum 1 is smallest. The developer 4 e in the developing means container 4 a is a mixture of toner and magnetic carrier, and is conveyed toward the development sleeve 4 b by the rotation of two developer stirring members 4 f while being stirred by the stirring members 4 f. [0059] The electrical resistance of the magnetic carrier in this embodiment is roughly 10 13 Ω.cm, and its particle diameter is 40 μm. The toner becomes negatively charged as it is rubbed by the magnetic carrier. The toner density in the developing means container 4 a is detected by a density sensor (unshown), and the toner density in the developing means container 4 a is kept constant by supplying the developing means container 4 a with a proper amount of toner from a toner hopper 4 g, based on the detected toner density in the container 4 a. [0060] The development sleeve 4 b is positioned so that the smallest distance between its peripheral surface and the peripheral surface of the photosensitive drum 1 is 300 μm. It is rotationally driven in the direction indicated by an arrow mark R 4 so that the movement of its peripheral surface in the developing portion c becomes opposite to the rotational direction R 1 (counterclockwise direction) of the peripheral surface of the photosensitive drum 1 in the developing portion c. [0061] A preset development bias is applied to the development sleeve 4 b from an electric power source S 2 . The development bias applied to the development sleeve 4 b in this embodiment is an oscillatory voltage, which is a combination of DC voltage (Vdc) and AC voltage (Vac), more specifically, the combination of −350 V of DC voltage, and an AC voltage which is 8 kV in peak-to-peak voltage. [0062] The transfer roller 5 is kept pressed upon the photosensitive drum 1 , with the application of a preset amount of pressure, forming thereby a transfer portion d. It rotates in the clockwise direction R 5 . To the transfer roller 5 , a transfer bias (which is positive bias, being therefore opposite in polarity to the normal polarity, that is, the negative polarity, to which toner is charged). By the application of this transfer bias, a toner image on the peripheral surface of the photosensitive drum 1 is transferred onto a sheet of recording medium P, such as paper, as the second image bearing member, in the transfer portion d. [0063] The fixing apparatus 6 has a fixation roller 6 a and a pressure roller 6 b, which are rotatable as necessary. After the transfer of the toner image from the photosensitive drum 1 onto the surface of the recording medium P, the recording medium P is conveyed through the fixation nip formed between the fixation roller 6 a and pressure roller 6 b. While the recording medium P is conveyed through the fixation nip, the toner image is thermally fixed with the heat and pressure from the fixation roller 6 a and pressure roller 6 b. [0064] After the transfer of a toner image from the surface of the photosensitive drum 1 onto the recording medium P, the peripheral surface of the photosensitive drum 1 is cleaned by the cleaning apparatus 7 . To describe more concretely, the peripheral surface of the photosensitive drum 1 is rubbed by the cleaning blade 7 a of the cleaning apparatus 7 , in the cleaning portion e, that is, the point of contact between the cleaning blade 7 a and the peripheral surface of the photosensitive drum 1 , being thereby cleared of the toner remaining on the peripheral surface of the peripheral surface of the photosensitive drum 1 . After the cleaning of the peripheral surface of the photosensitive drum 1 , the photosensitive drum 1 is used for forming the next portion of the image, or the next image; the photosensitive drum 1 is repeatedly used for image formation. [0065] A pre-exposing means 8 (charge removing optical means) removes the electric charge remaining on the peripheral surface of the photosensitive drum 1 after the cleaning of the peripheral surface of the photosensitive drum 1 , by irradiating the peripheral surface of the photosensitive drum 1 with light, so that the cleaned portion of the peripheral surface of the photosensitive drum 1 becomes virtually zero in potential before it is charged again. [0066] FIG. 3 is a diagram of the operational sequence of the above described printer. [0000] a. Initial Rotation Step (Preliminary Multiple Rotation Step) [0067] The initial rotation step is the step (warm-up step) which is carried out immediately after the printer is turned on. That is, as the electric power source switch of the printer is turned on, the various processing devices of the printer are made to prepare themselves for image formation; for example, the photosensitive drum 1 is rotationally driven for a preset length of time, and the fixation roller of the fixing apparatus is increased in temperature to a preset level. [0000] b. Preparatory Rotation Step (Preliminary Rotation Step) [0068] The preparatory rotation step is the rotation step between the end of the initial rotation step and when an actual image forming step (printing step) begins to be carried out. In a case where a printing signal is inputted during the initial rotation step, an image forming operation is started as soon as the initialization rotation step ends. In a case where no print signal is inputted during the initialization rotation step, the main motor is temporarily stopped after the ending of the initialization rotation step, and the rotational driving of the photosensitive drum 1 is stopped. Then, the printer is kept on standby until a printing signal is inputted. As a printing signal is inputted, the preparatory rotation is carried out. [0069] In this embodiment, it is in this preparatory rotation step that the program for computing and determining the proper value for the peak-to-peak value (AC current value) for the AC voltage to be applied in the charging step of the image forming operation, is carried out. This subject will be described later in more detail. [0000] c. Printing Step (Image Formation Step) [0070] As soon as the preset preparatory rotation step ends, the printing step, that is, the step for forming an image on the rotating photosensitive drum 1 is started. In the printing step, a toner image is formed on the peripheral surface of the rotating photosensitive drum 1 ; the toner image is transferred onto the recording medium; the toner image is fixed by the fixing apparatus; and the print is discharged from the printer. [0071] When the printer is in the continuous printing mode, the above described printing sequence is repeated until a preset number (n) of prints are outputted. [0000] d. Paper Interval [0072] The paper interval is the period between when the trailing edge of a given sheet of recording medium passes the transfer portion d, and when the leading edge of the following sheet of recording medium reaches the transfer portion d, while the printer is in the continuous recording mode, that is, the period in which no sheet of recording medium is being passed through the transfer portion d. [0000] e. Post-Rotation Step [0073] The post-rotation step is the step in which the driving of the main motor is continued for a while to rotationally driving the photosensitive drum 1 , and also, to carry out preset post-operations, after the printing step for the last sheet of recording medium is completed. [0000] f. Standby Step [0074] As soon as the post-rotation step is completed, the rotation of the main motor is stopped, stopping thereby the rotational driving of the photosensitive drum 1 , and then, the printer is kept on standby until the next print start signal is inputted. [0075] In a case where only a single copy is to be made, the printer is put through the post-rotation step after the completion of the printing of the single copy. Then, it is kept on standby after the completion of the post-rotation step. [0076] If it happens that a print start signal is inputted while the printer is kept on standby, the printer begins the pre-rotation step. [0077] The period in which the printer is performing the step c is the image formation period, and the initial rotation step (a), preparatory rotation step (b), paper interval (d), and post-rotation step (e) are the periods in which no image is formed. [0078] FIG. 4 is a block diagram of the circuit for applying the charge voltage to the charge roller 2 , and shows the general structure of the charging apparatus 200 . [0079] As a preset oscillatory voltage (bias voltage (Vdc+Vac)), which is a combination of a DC voltage, and an AC voltage (with a frequency f) is applied to the charge roller 2 through the metallic core 2 a, the peripheral surface of the rotating photosensitive drum 1 is charged to a preset potential level. [0080] An electric power source S 1 , which is the means for applying voltage to the charge roller 2 , has both an electric power source 11 (DC power source) and an electric power source (AC power source). [0081] A control circuit 13 , which is a controlling means, has the function of controlling the abovementioned DC power source 11 and AC power source 12 of the electric power source S 1 so that one of the DC and AC voltage is applied to the charge roller 2 , or both voltages are applied at the same time to the charge roller 2 . The control circuit 13 has also the function of controlling in value the DC voltage applied to the charge roller 2 from the DC power source 11 , and the peak-to-peak voltage of the AC voltage applied to the charge roller 2 from the AC power source 12 . [0082] A measurement circuit 14 is a circuit used as the means for measuring value of the AC component of the AC current which flows to the charge roller 2 from the power source S 1 . The information regarding the AC current value (or peak-to-peak voltage) measured by this circuit 14 is inputted to the above described control circuit 13 . [0083] The measurement circuit 15 is a DC current detecting means for detecting the value of the AC component which flows from the power source S 1 to the charge roller 2 . The information regarding the DC current value detected by this circuit 15 is inputted to the above described control circuit 13 . [0084] The environment sensor 16 is an environment sensor used as the means for detecting the conditions of the environment in which the printer is set up. It is a combination of a thermometer and a hygrometer. The information regarding the operational environment of the printer is inputted to the abovementioned control circuit 13 from this environment sensor 16 . [0085] That is, the control circuit 13 obtains the information regarding the AC current value (or peak-to-peak voltage value) from the measurement circuit 14 ; the information regarding the DC current value from the DC current measurement circuit 15 ; and the environmental information from the environment sensor 16 . The control circuit 13 has the function of carrying out the program for computing and determining the proper peak-to-peak value for the AC voltage applied to the charge roller 2 in the charging step in the printing step. [0086] Next, the method for controlling the AC bias applied to the charge roller 2 during the printing operation will be described. [0087] The inventors of the present invention discovered through various studies that the discharge current amount numerated according to the following definition can be used as a substitute for the actual amount of AC discharge, and also that there is a strong relationship between this discharge current amount and the shaving of photosensitive drum, formation of an image having the appearance of flowing water, and level of uniformity with which a photosensitive member is charged. [0088] That is, referring to FIG. 5 , when the value of the peak-to-peak voltage Vpp is no more than the discharge start voltage Vth×2 (V) (when peak-to-peak voltage in no discharge range), there is a linear relationship between the value of the peak-to-peak voltage and the value of the AC current Iac. However, as the peak-to-peak voltage value increases past the discharge start voltage Vth×2, that is, as the peak-to-peak voltage increases into the discharge range, the relationship shifts in such a direction that the discharge current Iac increases faster than in the non-discharge range. However, in the case of a similar experiment conducted in the vacuum condition in which electrical discharge does not occur, the linear relationship remains the same even after the increase of the peak-to-peak voltage beyond the discharge start voltage Tth×2 (V). Thus, it is reasonable to think that this difference is the amount of the increase ΔIac of increase in the AC current Iac, which contributes to the discharge. [0089] Hereafter, α stands for the ratio between the current Iac and the peak-to-peak voltage Vpp which is less than the discharge start voltage Vth×2 (V). Thus, the amount of the AC current other than the AC current attributable to discharge, that is, the current which flows through the area of contact (which hereafter will be referred to as “nip current”), etc., is α.Vpp. Thus, the difference between the Iac measured when a voltage, the peak-to-peak voltage of which is higher than the discharge start voltage Vth×2 (V), and α.Vpp, is defined as “discharge current amount ΔIac” which can be used as the substitute for the amount of discharge: [0000] Δ Iac=Iac−α.Vpp. [0090] In a case where the photosensitive drum is charged while the charge voltage or charge current is kept constant, the amount of discharge current is affected by the environmental factors and the cumulative usage of the photosensitive drum and charge roller. This phenomenon occurs because the relationship between the peak-to-peak voltage and discharge current amount, and the relationship between the AC current value and discharge current amount (value), change. [0091] In the case where the charge voltage is controlled so that the AC current remains constant, the charge voltage is controlled so that the total amount of current which flows from a charging member to a member to be charged. As described above, the total amount of current is the sum of the nip current α.Vpp and the amount ΔIac of the current flowed by the discharge which occurs across the area of no contact. Thus, in the case where the charge voltage is controlled so that the AC current remains constant, not only is the discharge current, that is, the very current which is necessary to charge a subject to be charged, but also, the nip current is controlled. [0092] Therefore, the discharge current amount is not actually controlled. That is, even if the charge voltage is controlled so that the charge current remains constant at a preset value, the amount of discharge current naturally reduces if the amount of nip current is increased by the changes caused to the charging member materials by the environmental changes. Further, the reduction in the nip current causes the discharge current to increase. Therefore, even the method for controlling the charge voltage so that the amount of AC current remains constant cannot perfectly prevent the increase or decrease in the amount of the discharge current. Thus, when this method was employed for the longevity of a photosensitive drum, it was difficult to uniformly charge a photosensitive drum while preventing the photosensitive drum from being shaved. [0093] As described above, because of the changes in the electrical resistance, capacity, and materials of an image bearing member, the changes in the electrical resistance, capacity, and materials of a charging member, or the environmental changes, it is difficult to accurately obtain the value of Vth in the discharge start voltage Vth×2 (V). Further, as for the relationship between the peak-to-peak voltage and AC current in the discharge range, as the distance from the discharge start point increases, the discharge current increases in the rate with which it increases, and therefore, the relationship becomes nonlinear. [0094] Based on the discoveries described above, it became evident that it is difficult to precisely obtain the amount ΔIac of the discharge current. [0095] Thus, in order to ensure that the amount of discharge current remains constant at a desired value, the inventors of the present invention controlled a charging apparatus using the following method. [0096] Next, the method for determining the value for the peak-to-peak voltage for a charging apparatus, which keeps the amount of discharge current at a desired amount Ih, will be described. [0097] Referring to FIG. 6 , in this embodiment, multiple test biases, which were different in peak-to-peak voltage, were applied, with preset timing, with the pre-exposure light turned on and the DC voltage kept constant at −500 V, during a period in which no image was formed; the AC voltage was increased (or decreased) in steps, while detecting the DC current value at each voltage level. Then, the AC voltage value, which corresponded to the saturation point of the DC current value, that is, the AC voltage value, above which the rate of change (rate of increase) was below preset value, was defined as the minimum AC voltage value (peak-to-peak voltage V 0 ). Shown in FIG. 7 is the result of the measurements in an environment in which the temperature and humidity were 23° C. and 50%, respectively. As the AC voltage was increased, the DC voltage proportionally increased, reaching −35 μA when the AC voltage was 1,500 Vpp. However, as the AC voltage increased beyond 1,500 Vpp, the rate with which the DC current changed in value suddenly reduced. In this case, the rate with which the DC voltage changed remained at 0.0023=∥(DC current value)/AC voltage value)∥. In this embodiment, 1,500 Vpp, which was the smallest AC voltage value at which the rate of change fell below 0.0023, was the smallest peak-to-peak voltage V 0 . [0098] Further, as will be evident from FIG. 8 , an AC voltage value (point) above which the DC current remained stable in value, was the AC voltage value (point) to which the potential of the charged photosensitive drum 1 converged, and this voltage value V 0 corresponded to the discharge start point. [0099] Next, a peak-to-peak voltage Vp, which was greater in value than V 0 was selected. In this embodiment, 1,700 V was selected as the value for the peak-to-peak voltage Vp. Then, the AC current value was measured when V 0 =1,500 Vpp, and Vp=1,700 Vpp. Referring to FIG. 9 , the measured AC current values were: (V 0 , I 0 )=(1,500 Vpp, 2,000 μA), (Vp, IP)=(1,700 Vpp, 2,400 μA). [0100] Next, the relationships between the peak-to-peak voltage and AC voltage, more specifically, the mathematical relationships (function) between the peak-to-peak voltage and AC voltage, was obtained from the abovementioned measured values. One of the functions is F 1 (Vpp) (mathematical relationship between the peak-to-peak and AC current) shows the mathematical relationship between the peak-to-peak voltage level and AC current value when the smallest AC voltage (Vpp), that is, V 0 , was applied to the charging means. Another is F 2 (Vpp), which shows the mathematical relationship between the peak-to-peak voltage level and AC voltage value when a charge voltage which was greater in peak-to-peak value at least by one point than when V 0 is applied to the charging means. [0101] That is, for the discharge range, an approximate linear relationship (F 2 (Vpp)) is calculated based on the two points (V 0 , I 0 ) and (Vp, Ip) (Expression 1). For the non-discharge range, an approximate linear relationship (F 1 (Vpp)) was calculated, based on the two points (point 0) and (V 0 , I 0 ) (Expression 2). [0102] In this embodiment, the relationship between the peak-to-peak voltage and AC current was linearly approximated from the above described measured current values, with the use of the least squares method: [0000] Function F 2( Vpp )) Yα=α×α+ A   (Expression 1 [0000] Function F 1( Vpp )) Yβ=β×β  (Expression 2 [0103] Referring to FIG. 9 , the amount Ih of the discharge current is the difference between the straight line Yα obtained by approximation, and the straight line Yβ in the non-discharge range obtained by approximation. [0000] Ih = F   2  ( Vpp ) - F   1  ( Vpp )   = Y   α - Y   β   = ( αXα + A ) - ( β   X   β ) . [0104] Here, assuming that the peak-to-peak voltage value X, which can keep constant the discharge current value Ih, is Vpp, there is the following mathematical relationship: [0000] Ih =(α Vpp+A )−(β Vpp ). [0105] Therefore, the value of the peak-to-peak Vpp, which can keep constant the discharge current amount at Ih, can be calculated with the use of the following Expression 3: [0000] Vpp =( Ih−A )/(α−β)   (Expression 3). [0106] Referring to FIG. 9 , in this embodiment, when the desired discharge current amount Ih was set to 50 μA, the peak-to-peak voltage value calculated with the use of Expression 3 given above was 1,575 (Vpp). [0107] The control circuit 13 switches the peak-to-peak voltage to be applied to the charging member, to the obtained Vpp, and made the printer to move onto the above described image formation steps (voltage control at Vpp). [0108] As described above, the peak-to-peak voltage value necessary for keeping the discharge current amount constant at a preset value in actual image forming steps, was calculated during each preparatory rotation step, and during the actual printing steps, the charge voltage was kept constant at the voltage level obtained by calculation during the preparatory rotation step. With the employment of this control method, it was possible to absorb fluctuation in the electrical resistance value of the charge roller 2 , which is attributable to the nonuniformity in manufacturing processes, changes in the properties of the charge roller materials attributable to the changes in the operational environment, high voltage fluctuation of the main assembly of the image forming apparatus. Therefore, it was possible to reliably keep the discharge current amount constant at a desired value. [0109] When the printer in this embodiment was tested for durability while the charge voltage was controlled with the use of the above described method, the deterioration and shaving of the photosensitive member (as image bearing member) did not occur regardless of the changes in the operational environment. More specifically, the service life of the photosensitive drum was extended roughly 10% compared to when the charging apparatus was controlled with the use of the conventional method in which the charge voltage is controlled so that the AC current amount remains constant. Further, this embodiment made it possible to more accurately calculate the relationship between the peak-to-peak voltage and AC current in the discharge range, than the method proposed in Patent Document 1. [0110] FIG. 21 graphically shows the comparison between the conventional method for setting the discharge current amount, and the method, in this embodiment, for setting the discharge current amount. [0111] In the case of the conventional method, the relationship between the peak-to-peak voltage and AC current is nonlinear in the discharge range. Therefore, the discharge start point obtained by calculation is greater in value than that obtained with the use of the method in this embodiment. In other words, even though the conventional method and the method in this embodiment are the same in the necessary amount of discharge current, the former was greater in the value (Vpp) of the AC bias applied as the charge bias. [0112] The necessary AC bias value (Vpp) for obtaining a desired amount of discharge current, which was calculated with the use of the method in this embodiment was better by as much as 30% compared to the conventional method, in terms of the difference from the actual discharge start point. [0113] In this embodiment, the amount of the discharge current was controlled by switching the magnitude of the peak-to-peak voltage of the AC voltage applied to the charge roller 2 . However, this embodiment is not intended to limit the present invention in scope. [0114] For example, the AC current value measurement circuit 14 , as an AC current detecting means, in FIG. 4 , may be replaced with a peak-to-peak voltage measurement circuit as a peak-to-peak voltage detecting means, so that AC current is applied instead. With this replacement, the peak-to-peak of the AC voltage can be measured to control the AC power source in the amount of AC current output by the control circuit 13 so that AC current is always provided by the amount necessary to provide discharge current by a desired amount during the printing steps. [0115] Further, in this embodiment, the discharge current amount Ih, and the value of the peak-to-peak voltage of the AC voltage applied in the preparatory rotation step, are set in anticipation of a specific operational environment. However, in the case of a printing apparatus provided with an environment sensor (combination of thermometer and hygrometer), it is possible to variably set the value for the peak-to-peak voltage and the value for the discharge current amount, in response to the detected environmental variables, so that the photosensitive drum can be even more reliably and uniformly charged. [0116] As described above, in this embodiment, AC voltage was applied during the preparatory rotation step, while increasing in steps the AC voltage in peak-to-peak voltage. Then, the peak-to-peak voltage value was measured at the lowest AC voltage point (value V 0 ), that is, the point at which the AC current virtually stopped increasing (became stable), and at one or more points in the discharge range, while applying the charge voltage to the charge roller 2 . Then, based on the AC current values measured at the above described two or more points, the magnitude for the peak-to-peak voltage of the AC voltage to be applied during the printing steps, was determined, so that the AC voltage, the peak-to-peak voltage of which was suitable for always providing a desired amount of discharge current, or so that the AC current flowed by the AC voltage always supplied the desired amount of discharge current. Thus, not only was it possible to prevent the deterioration and shaving of the photosensitive member, but also, it was possible to uniformly charge the photosensitive member. Therefore, it was possible to prolong the life of the photosensitive member, and also, to improve the printer in image quality. [0117] Further, this embodiment made it possible to absorb the nonuniformity in properties, among charging apparatuses, which was attributable to manufacturing processes. Thus, this embodiment can widen the choice for the materials for a charging apparatus, and also, can lower the level of accuracy with which a charging apparatus is to be manufactured. Thus, this embodiment can reduce the manufacturing cost for a charging apparatus, making it possible to provide a user with a charging apparatus which is substantially lower in cost than a conventional charging apparatus. Embodiment 2 [0118] Referring to the flowchart in FIG. 10 , in this embodiment, when the image forming apparatus was on, but, not forming an image, the pre-exposure light was turned on, and the DC voltage was kept constant at −500 V, and multiple test biases, which were different in peak-to-peak voltage, were applied. More specifically, the AC voltage was increased (decreased) in steps, and the amount of the DC current was detected at each AC voltage level to find the point beyond which the DC current did not significantly increase (decrease). Then, the AC voltage value corresponding to this point was defined as the smallest value V 0 of the AC voltage. [0119] Also in this embodiment, as in the first embodiment, the DC current value changed in the rate of change (rate of increase) at −35 μA, when the AC voltage was 1,500 V in peak-to-peak value, as is shown in FIG. 7 which shows the results of the measurements made in an operational environment in which temperature and humidity were 23° C. and 50%, respectively. In this case, 1,500 Vpp was the value of V 0 . [0120] Further, as will be evident from FIG. 8 , the point at which the DC current became stable in value was the point which corresponded to the potential level to which the potential of the photosensitive drum 1 converged. This point which corresponded to the V 0 was the discharge start point. [0121] Next, the peak-to-peak voltage Vp, which was greater in value than the peak-to-peak voltage V 0 , was selected. In this embodiment, 1,700 Vpp was selected. [0122] Further, the studies made earnestly by the inventor of the present invention revealed that because of the microscopic nonuniformity in the electrical resistance of the materials of the photosensitive member and/or charging member, discharge (abnormal discharge) sometimes occurs when the AC voltage is in the non-discharge range, but, is very close to the discharge start point, and therefore, when the equation for the straight line connecting the discharge start point and Point (0, 0) is obtained by approximation, the equation is slightly off in terms of the inclination of the straight line. [0123] Thus, in this embodiment, a peak-to-peak voltage Vq, which is less in value than the peak-to-peak voltage V 0 , was selected, which was 1,400 Vpp. [0124] Next, the AC current value was measured at three points, that is, when the peak-to-peak voltage was V 0 (=1,500 Vpp), Vp (=1,700 Vpp), and Vq (=1,400 Vpp). Referring to FIG. 11 , the measured current values were: (V 0 , I 0 )=(1,500 Vpp, 2,000 μA); (Vp, Ip)=(1,700 Vpp, 2,400 μA); and (Vq, Iq)=(1,400 Vpp, 1,840 μA). [0125] Next, from the measured values mentioned above, the relationship between the peak-to-peak voltage and AC current, more specifically, functions which numerically define the relationship between the peak-to-peak voltage and the amount of AC current, was obtained. One of the functions is F 1 (Vpp), which numerically defines the relationship between the peak-to-peak voltage and the amount of AC current, based on the relationships between the AC voltage and the amount of AC current, which were obtained when two or more AC voltages, which were lower in peak-to-peak voltage than the AC voltage V 0 , were applied to the charging means. Another function is F 2 (Vpp), which numerically defines the relationship between the peak-to-peak voltage and the amount of AC current, based on the relationships between the AC voltage and the amount of AC current, which were obtained when the AC voltage V 0 , and two or more AC voltages, which were higher in peak-to-peak voltage than the AC voltage V 0 , were applied to the charging means. [0126] That is, as for the discharge range, an expression for Function F 2 (Vpp), which corresponds to the straight line between the two points (V 0 , I 0 ) and (Vp, Ip), was approximated (Expression 1). As for the non-discharge range, an expression for Function F 1 (Vpp), which corresponds to the straight line approximated from the two point, that is, Point (0, 0) and (Vq, Iq) (Expression 2). [0127] In this embodiment, the relationship between the peak-to-peak voltage and AC current were linearly approximated by the control circuit 13 from the measured current values mentioned above, with the use of the least squares method. That is: [0000] Function F 2( Vpp )) Yα=α×α+A   (Expression 1 [0000] Function F 1( Vpp )) Yβ=β×β.   (Expression 2 [0128] Referring to FIG. 11 , the amount Ih of the discharge current is the difference between the approximated straight line Yα, and the approximated straight line Yβ in the non-discharge range. [0000] Ih = F   2  ( Vpp ) - F   1  ( Vpp )   = Y   α - Y   β   = ( αXα + A ) - ( β   X   β ) . [0129] Here, assuming that the peak-to-peak voltage value, which can keep constant the discharge current value Ih, is Vpp, there is the following mathematical relationship: [0000] Ih =(α Vpp+A )−(β Vpp ). [0130] Therefore, the value of the peak-to-peak Vpp, which can keep constant the discharge current amount at Ih, can be calculated with the use of the following mathematical expression: [0000] Vpp =( Ih−A )/(α−β)   (Expression 3). [0131] Referring to FIG. 11 , in this embodiment, when the desired discharge current amount Ih was set to 50 μA, the necessary peak-to-peak voltage value was 1,562 (Vpp). [0132] The control circuit 13 switched the value of the peak-to-peak voltage to be applied to the charging member, to the obtained Vpp, and made the printer to move onto the above described image formation steps (AC voltage was kept constant at Vpp). [0133] By structuring the control circuit 13 so that the charge voltage is controlled as described above, the peak-to-peak voltage value necessary for keeping the discharge current amount constant at a desired value can be precisely obtained regardless of the presence of microscopic nonuniformity in the electrical resistance of the materials of the photosensitive member and/or charging member. Embodiment 3 [0134] Referring to the flowchart in FIG. 12 , in this embodiment, when the image forming apparatus was on, but, not forming an image, the pre-exposure light was turned on, and the DC voltage was kept constant at −500 V, and multiple test biases, which were different in peak-to-peak voltage, were applied. More specifically, the AC current was increased (decreased) in steps, and the amount of the DC current was detected at each AC current level to find the point beyond (below) which the DC current did not significantly increase (decrease). Then, the DC current value corresponding to this point was defined as the smallest value Io for the AC current. [0135] Referring to FIG. 13 , which shows the results of the measurements made in an operational environment in which temperature and humidity were 23° C. and 50%, respectively, when the AC current value was 2,000 μA, the DC current value became smaller in rate of change after it reached −35 μA. In this case, the rate of change (rate of increase) of the DC current value before the DC current value reached 2,000 μA was 0.0175 (=∥(DC current value)/(AC current value)∥). In this embodiment, therefore, 2,000 μA, that is, the AC current value (smallest value) above which the rate of change of the DC current value was no more than 0.00175, is the value of I 0 . [0136] Further, as will be evident from FIG. 14 , the point at which the DC current became stable in value is the point which corresponds to the potential level to which the potential of the photosensitive drum 1 converges. This point which corresponds to the I 0 is the discharge start point. [0137] Next, the AC current value Ip, which was greater in value than the AC current value I 0 was selected. In this embodiment, 2,400 μA was selected. Then, the peak-to-peak voltage value was measured when the AC current value was I 0 (=2,000 μA), and Ip (=2,400 μA). Referring to FIG. 15 , the measured peak-to-peak voltage values were: (V 0 , I 0 ) (1,500 Vpp, 2,000 μA), and (Vp, Ip)=(1,700 Vpp, 2,400 μA). [0138] Next, the relationship between the peak-to-peak voltage and AC voltage, more specifically, numerical relationships between the peak-to-peak voltage and AC current were obtained. One of the numerical relationships is F 1 (Vpp) obtained by connecting the point (V 0 , I 0 ) and point (0, 0) with a straight line. Another one is F 2 (Vpp) obtained from the relationship between the AC current value at point (V 0 , I 0 ) and those at two or more points (Vp, Ip) which were greater in AC current value than point (V 0 , I 0 ). [0139] That is, as for the discharge range, an expression for Function F 2 (Vpp), which corresponds to the straight line between the two points (V 0 , I 0 ) and (Vp, Ip), was approximated (Expression 1). As for the non-discharge range, an expression for Function F 1 (Vpp) was obtained by approximateion based on the two points, that is, point (0, 0) and (Vq, Iq) (Expression 2). [0140] In this embodiment, the relationship between the peak-to-peak voltage and AC current were linearly approximated by the control circuit 13 from the measured current values mentioned above, with the use of the least squares method. That is: [0000] Function F 2( Vpp )) Yα=α×α+A   (Expression 1 [0000] Function F 1( Vpp )) Yβ=β×β   (Expression 2 [0000] Here, F 2( Vpp )= F 1( Vpp )+ Ih. [0141] Here, when an AC current value is Iac 1 , and the corresponding peak-to-peak voltage value is Vpp, Expressions 1 and 2 become: [0000] Iac 1=α Vpp+A   (Expression a) [0000] Iac2=β Vpp   (Expression b). [0142] Here, Iac 2 stands for the AC current value which corresponds to Vpp on approximated straight line Yβ in non-discharge range. [0143] Since discharge current amount Ih is the difference between Iac 1 and Iac 2 , [0000] Ih=Iac 1− Iac 2   (Expression c). [0144] From Expressions a and b, AC current value Iac 1 , which provides discharge current amount Ih, is obtained from the following expression: [0000] Iac 1=(α Ih−βA )/(α−β)   (Expression 4) [0145] Referring to FIG. 15 , in this embodiment, when the desired discharge current amount Ih was set to 50 μA, the necessary amount of AC current was calculated with the use of the equation given above was 2,150 μA. [0146] Then, the control circuit 13 switched the value of the AC current to be supplied to the charging member, to the AC current value Iac 1 , and made the printer to move onto the above described image formation steps (AC current was kept constant at Iac 1 ) Embodiment 4 [0147] Referring to FIG. 16 , in this embodiment, while no image was being formed, the AC current was increased (decreased) in amount in steps by applying multiple test biases different in peak-to-peak voltage, with the pre-exposure light kept on, and the DC voltage kept at −500 V, and the DC voltage value was detected at each test bias to find out the smallest value I 0 of the AC current, beyond which the DC current did not significantly change. [0148] Also in this embodiment, as the AC current value was increased beyond 2,000 μA, the DC current value became stable at −35 μA, as shown in FIG. 13 , which shows the results of the measurements in the operational environment in which the temperature and humidity were 23° C. and 50%, respective, as they were in the third embodiment. In this case, 2,000 μA is the value of I 0 . [0149] Further, as will be evident from FIG. 14 , the point which corresponds to the DC current value beyond which the DC current is stable in amount is the point which corresponds to the potential level to which the charge of the photosensitive drum 1 converges. Thus, this Io is the discharge start current value (point). [0150] Further, the studies earnestly made by the inventors of the present invention revealed that even in the non-discharge range, electrical discharge occurs in the adjacencies of the discharge start point, because of the microscopic nonuniformity of the materials of the photosensitive member and/or charging member, in terms of electrical resistance, although the occurrence is very rare. Thus, when approximating the straight line which connects the discharge start point and zero point, there occurs a slight deviation in inclination. [0151] In this embodiment, therefore, AC current value Iq, which is smaller than AC current value I 0 was selected, which was 1,800 μA. [0152] Further, AC current value Ip, which was greater than AC current value I 0 , was selected, which was 2,400 μA. [0153] Then, the peak-to-peak voltage was measured when the AC current value was I 0 (=2,000 μA), Ip (=2,400 μA), and Iq (=1,800 μA). The measured values of the peak-to-peak voltage were (V 0 , I 0 )=(1,500 Vpp, 2,000 μA), (Vp, Ip)=(1,700 Vpp, 2,400 μA), and (Vq, Iq)=(1,370 Vpp, 1,800 μA) as shown in FIG. 17 . [0154] Next, the relationship between the peak-to-peak voltage and AC current, more specifically, numerical relationships between the peak-to-peak voltage and AC current, were obtained from the measured values given above. One is the numerical expression for Function F 1 (Vpp) obtained from the relationship between the values of the peak-to-peak voltage measured at one or more points at which the AC current was smaller in value than when AC current value Io was flowed to the charging means. Another one is the numerical expression for Function F 2 (Vpp) obtained from the relationship between the values of the peak-to-peak voltage measured at the point at which the AC current value was I 0 , and at least one point where the AC current value is greater than I 0 . [0155] That is, in the case of the discharge range, the straight line is approximately calculated based on two points (V 0 , I 0 ) and (Vp, Ip) (F 2 ) (Vpp) (Expression 1). In the case of the non-discharge range, the numerical expression for the straight line was approximated from (0, 0) and (Vq, Iq) (F 1 ) (Expression 2). [0156] In this embodiment, the relationship between the peak-to-peak voltage and AC current was linearly approximated by the control circuit 13 from the two points (V 0 , I 0 ) and (Vp, Ip), with the use of the least squares method. That is: [0000] Function F 2( Vpp )) Yα=α×α+A   (Expression 1 [0000] Function F 1( Vpp )) Yβ=β×β   (Expression 2 [0000] Here, F 2( Vpp )= F 1( Vpp )+ Ih. [0157] Here, when an AC current value is Iac 1 , and the corresponding peak-to-peak voltage value is Vpp, Expressions 1 and 2 become: [0000] Iac 1=α Vpp+A   (Expression a) [0000] Iac2=βVpp   (Expression b). [0158] Here, Iac 2 stands for the AC current value which corresponds to Vpp on approximated straight line Yβ in non-discharge range. [0159] Since discharge current amount Ih is the difference between Iac 1 and Iac 2 , [0000] Ih=Iac 1− Iac 2   (Expression c). [0160] From Expressions a and b, AC current value Iac 1 , which provides discharge current amount Ih, is obtained from the following expression: [0000] Iac 1=(α Ih−βA )/(α−β)   (Expression 4). [0161] Referring to FIG. 17 , in this embodiment, when the desired discharge current amount Ih was set to 50 μA, the necessary amount of AC current was calculated with the use of the equation given above was 2,123 μA. [0162] Then, the control circuit 13 switched the value of the AC current to be supplied to the charging member, to the AC current value Iac 1 , and made the printer to move onto the above described image formation steps (AC current was kept constant at Iac 1 ). [0163] With the provision of the control structure described above, it was possible to precisely obtain a desired amount of discharge current, regardless of the presence of nonuniformity in microscopic level in the electrical resistance among photosensitive members and/or charging members. (Miscellanies) [0164] In the preferred embodiments described above, Point (0, 0) was used to approximate the straight line in the non-discharge range. However, a point other than Point (0, 0) may be used. That is, as long as the amount of the current which flows at a point when the peak-to-peak voltage at this point is Vpp can be known in advance, this point and another point of measurement can be used to obtain the relationship between the peak-to-peak voltage and AC current. [0165] Also in the preferred embodiment, the number of the points (V, I) of measurement, beside the discharge start point, was minimum (one). However, the number of the points of measurement may be two, three, or more. In any case, the discharge current amount can be easily obtained by approximating the linear relationship between the peak-to-peak voltage and discharge current, with the use of the least squares method, for example. [0166] The multiple AC voltages different in peak-to-peak voltage, which were applied to the charging means in the order of the magnitude of their peak-to-peak voltage, to measure the AC current value while no image was formed, may be changed according to the image formation count, operational environment, thickness of the film(s) of an image bearing member, or at least one of the DC current values detected by the DC current detecting means. Similarly, the multiple AC currents different in value, which were flowed through the charging means in the order of their current value, to measure the peak-to-peak voltage values while no image was formed, may be changed according to the image formation count, operational environment, thickness of the film(s) of an image bearing member, or at least one of the DC current values detected by the DC current detecting means. [0167] Further, the amount Ih of the discharge current can be changed according to the image formation count, operational environment, thickness of the film(s) of an image bearing member, or at least one of the DC current values detected by the DC current detecting means. That is, in the preceding embodiments, the discharge current amount Ih, the value of the alternating electric field to which the charging member is subjected during the preparatory rotation step, were variable according to the environmental factors detected by the environment sensor 15 . However, the method for detecting the film thickness of a photosensitive member from the DC current value has been widely known, and it is also effective to design a charging apparatus so that the discharge current amount Ih, and the value of the alternating electric field to be applied during the preparatory rotation step, can be changed according to the detected thickness of the film(s) of a photosensitive member and the detected DC current value. Further, it is also effective to design the charging apparatus so that the cumulative image formation count is stored, and the discharge current amount Ih, and the value of the alternating electric field to be applied during the preparatory rotation step, can be changed according to the stored cumulative image formation count. [0168] Further, in each of the above described preferred embodiments, the programs for determining, by computation, the proper value for the peak-to-peak voltage for the AC voltage to be applied in the charging step of the printing step, were carried out during the preparatory rotation step, that is, one of the steps in which no image was formed by the printer. The steps in which the programs are to be carried out does not need to be limited to the one in the preceding embodiments. That is, the programs may be carried out in any, or two or more, of the steps in which no image is formed, for example, the startup rotation step, paper intervals, or post-rotation step. [0169] Further, in each of the preferred embodiments described above, the image forming apparatus was provided with a cleaning member. However, the present invention is also applicable to the charge process controlling means of a so-called cleaner-less image forming apparatus, that is, an image forming apparatus which has no cleaning member, and cleans its photosensitive member with its developing apparatus at the same time as it develops a latent image with the developing apparatus. Such an application brings forth the same effects as those provided by the preferred embodiments. [0170] Further, the photosensitive drums 1 in each of the preceding embodiments may be replaced with a photosensitive drum of the direct injection type, which is provided with a charge injection layer, the surface electrical resistance of which is in the range of 10 9 −10 – Ω.cm. Even in the case of a photosensitive drum having no charge injection layer, effects similar to those obtainable with the abovementioned photosensitive member with a charge injection layer can be obtained as long as the electrical resistance of its charge transfer layer is within the abovementioned range. Further, instead of the photosensitive drum 1 in the above-described embodiments, a photosensitive member which is made of amorphous silicon, and the volumetric resistance of the surface layer of which is roughly 10 13 Ω.cm, may be used. [0171] Also in each of the above described embodiments, a charge roller was used as a flexible charging member of the contact type. However, in place of the charge roller, a charging member different in shape and/or material, for example, a fur brush, a piece of felt or fabric, etc., may be used. Further, a charging member, which is better in elasticity, electrical conductivity, surface properties, durability, etc., may be obtained by using in combination various substances as the materials for a charging member. [0172] As for the waveform for the alternating voltage component (AC component: voltage which periodically change in value) to be applied to the charge roller 2 and development sleeve 4 b, any of the sinusoidal form, rectangular form, triangular form, etc., may be used as fit. Further, the alternating component of the AC voltage may be created by periodically turning on and off a DC power source. In such a case, the waveform of the AC component is rectangular. [0173] Also in each of the above described preferred embodiments, the exposing apparatus 3 used as the means (information writing means) for exposing the charged portion of the peripheral surface of the photosensitive drum 1 was a laser scanner. However, the exposing means may be a digital exposing means made up of an array made up of light emitting elements in solid state, for example, LEDs, or an analog image exposing means, the original illuminating light source of which is a halogen lamp, a fluorescent lamp, or the like. [0174] Also in each of the above described preferred embodiments, the first image bearing member was the photosensitive member 1 . However, the first image bearing member may be an electrostatically recordable dielectric member or the like. In the case where the first image bearing member is an electrostatically recordable dielectric member, first, the surface of the electrostatically recordable dielectric member is uniformly charged, and then, an electrostatic latent image which reflects the information of a target image is written by selectively discharging numerous points of the charge surface of the dielectric member with the use of a charge removing means, such as a charge removing needle head, an electron gun, and the like. [0175] Also in each of the above described preferred embodiments, a transfer roller was used as the transferring means. However, the transferring means may be a transfer blade, transfer belt, or any other transferring means of the contact type. Further, it may be of the non-contact type, which uses a corona-based charging device. [0176] Also in each of the above described preferred embodiments, the image forming apparatus was of such a type that directly transfers onto recording medium, a monochromatic toner image formed on its photosensitive drum. However, the preferred embodiments are not intended to limit the present invention in scope. That is, the present invention is also applicable to a monochromatic image forming apparatus which employs an intermediary transferring member, such as a transfer drum or a transfer belt, and a full-color (multicolor) image forming apparatus which forms a multicolor or a full-color image by transferring in layers multiple monochromatic images. [0177] While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. [0178] This application claims priority from Japanese Patent Application No. 178505/2008 filed Jul. 8, 2008 which is hereby incorporated by reference.

A charging apparatus includes a charging device for electrically charging a photosensitive member; a bias applying device for applying to the charging member a charging bias voltage comprising a DC voltage component and a AC voltage component, wherein the bias applying device effect a constant voltage control with a constant AC component of the charging bias voltage; a AC detector for detecting a AC detected current when the charging member is supplied with a test bias voltage; a DC detector for detecting a DC detected current when the charging member is supplied with the test bias voltage; and a controller for controlling a charging bias voltage to be applied to the charging member; wherein the control means determines a peak-to-peak voltage Vo when a change rate of detected DC current provided by sequentially applying the test bias voltages having different peak-to-peak voltages in order of increasing or decreasing peak-to-peak voltage becomes not more than a predetermined level, and the control means sets a peak-to-peak voltage of the charging bias voltage on the basis of a detected AC current when a peak-to-peak voltage Vp larger than the peak-to-peak voltage Vo and a detected AC current when a peak-to-peak voltage Vq not larger than the peak-to-peak voltage Vo.

FIELD OF THE INVENTION [0001] The present invention relates to the field of compositions for animal feedstuffs. STATE OF THE ART [0002] The most common problem known to affect farm and companion animals is the damage caused by bacterial infections and mycotoxins produced by moulds ingested with their feed. Regarding bacterial infections, and in particular intestinal infections, these often present with severe diarrhoea which can compromise, even to a serious extent, the health of the animal and consequently the revenue of the farm as a whole. [0003] Regarding mycotoxins produced by moulds, their toxic effects on specific organs and on the physiological functions of animals, and their capacity to cause diseases such as toxicosis, have been known for some years. It is also known that carcinogenic mycotoxins, such as aflatoxins produced by moulds of the Aspergillus strain, can be transferred from cow's or goat's milk to man because they are stable and cannot be eliminated with normal heat treatments. Ocratoxin A is produced by Aspergillus and Penicillium species; if present in the feed, it can cause serious kidney diseases in pigs and in bird species. [0004] T-2 toxin, produced by Fusarium species, can cause necrosis of the digestive tract of animals. [0005] It is normally sought to overcome these drawbacks by using short chain organic acids, either alone or in a mixture, such as: formic acid (C 1 H 2 O 2 ), acetic acid (C 2 H 4 O 2 ), propionic acid (C 3 H 5 O 2 ), lactic acid (C 3 H 6 O 2 ), fumaric acid (C 4 H 4 O 4 ), butyric acid (C 4 H 8 O 2 ), citric acid (C 8 H 8 O 7 ) and benzoic acid (C 7 H 6 O 2 ). [0006] Among the limitations of using said organic acids is their strong corrosive action which can damage any equipment with which they come into contact. Salified forms with ammonium, calcium, sodium or potassium also produce a corrosive action which, though more limited, is nevertheless present. [0007] There are also certain physiological restrictions to the action of organic acids as such or in salified form when used as antibacterials in the diets of animals; in this respect organic acids are known to require an acidic pH in order to perform the actual antibacterial action, because under these conditions they are present in the undissociated RCOOH form. This undissociated RCOOH form passes through microorganism cell walls and, once inside, is dissociated according to intracellular pH. To maintain its intracellular pH the microorganism expels H + ; the level of dissociated organic acid thus rises and as it does not leave the microorganism, it kills it. [0008] In the intestines, however, the pH is slightly basic (around 7) so the presence of organic acid in undissociated form is very limited, and consequently the antibacterial function is also very limited. [0009] In the light of the aforesaid, therefore, there is an evident need to develop new compositions able to counteract the effects of moulds and bacteria present in animal feeds, but which do not exhibit the aforesaid drawbacks. [0010] The technique of microencapsulating organic acids with lipid substances was developed as a method for delivering organic acid to the intestines and to lower the pH therein, but the results obtained are rather unsatisfactory because of the buffering action of sodium bicarbonate produced by the pancreas as an intestinal pH regulator. Moreover, in addition to not being very effective, this technology is also very costly. [0011] The antibacterial action of certain fatty acid monoglycerides has been investigated in a number of studies, for example: [0012] 1. J. Kabara, Dennis M. Swieczkowski, Anthony J, Conley, Joseph P. Truant 1972 FATTY ACIDS AND DERIVATES AS ANTIMICROBIAL AGENTS. [0013] 2. G. Bergsson, J. Arnfinnsson S. Karlsson, O. Steingrimsson, H. Thormar 1998. IN VITRO INACTIVATION OF CHLAMYDIA TRACHOMATIS BY FATTY ACIDS AND MONOGLYCERIDES. [0014] 3. G. Bergsson, J. Arnfinnsson, O. Steingrimsson, H. Thormar 2001. IN VITRO KILLING OF CANDIDA ALBICANS BY FATTY ACIDS AND MONOGLYCERIDES. [0015] 4. H. Thormar, H. Hilmarsson, G. Bergsson 2005. STABLE CONCENTRATED EMULSIONS OF THE 1-MONOGLYCERIDE OF CAPRIC ACID (MONOCAPRIN) WITH MICROBICIDAL ACTIVITIES AGAINST THE FOOD-BORNE BACTERIA CAMPYLOBACTER JEJUNI, SALMONELLA SPP AND ESHERICHIA COLI; PCT/IS 2005/000026 “STABLE CONCENTRATED ANTI-BACTERIAL EMULSIONS OF MONOCAPRIN IN WATER”. [0016] 5. Hilmarsson, H. Thormar, J. H. Thrainsson, E. Gunnarsson 2006 EFFECT OF GLYCEROL MONOCAPRATE (MONOCAPRIN) ON BROILER CHICKENS: AN ATTEMPT AT REDUCING INTESTINAL CAMPYLOBACTER INFECTION. [0017] These studies have highlighted a promising but not exhaustive research direction; as far as current knowledge allows, there are no studies which confirm the specifically antibacterial and anti-mould action of compositions of short chain fatty acid monoglycerides combined with glycerol. BRIEF DESCRIPTION OF THE FIGURES [0018] FIG. 1 is an aqueous suspension of a composition of the invention shown by electron microscopy. [0019] FIG. 2 shows untreated feed inoculated with Fusarium. [0020] FIG. 3 shows feed inoculated with Fusarium and treated with 0.7% Monopropionin 43. SUMMARY OF THE INVENTION [0021] The present invention relates to compositions containing C 1 to C 7 fatty acid monoglycerides in percentages between 10% and 90% and glycerol between 10 and 90% by weight (calculated on the total composition weight) as antibacterials and anti-mould agents to be added to cereals, feed, and to general foodstuffs and drinking water intended for the feeding of animals. DETAILED DESCRIPTION OF THE INVENTION [0022] It has surprisingly been found that compositions containing C 1 to C 7 organic acid monoglyceride esters combined with glycerol have a strong antibacterial potency both at acidic pH (4.5) and at neutral pH as is present in animal intestines (i.e. pH 7). [0023] In the compositions of the invention, the organic acid monoglyceride esters as aforedefined are present in amounts between 10% and 90% and the glycerol between 10 and 90% by weight (calculated on the total composition weight); preferably said amounts are between 40%-90%, and 10%-60% respectively. [0024] The term “C 1 to C 7 organic acids” according to the invention refers preferably to the following acids: formic, acetic, propionic, lactic, butyric, citric, fumaric and benzoic acids. [0025] Butyric acid and propionic acid are particularly preferred. [0026] Examples of compositions according to the invention are compositions consisting of: [0027] (a) [0000] monoglyceride ester of butyric acid 42-47% diglyceride ester of butyric acid 5-8% triglyceride ester of butyric acid 0.5-2%   glycerol 45-50% [0028] (b) [0000] monoglyceride ester of propionic acid 45-50% diglyceride ester of propionic acid  8-12% triglyceride ester of propionic acid 1-3% glycerol 36-40% [0029] Specific examples of compositions according to the invention are compositions consisting of: [0030] (c) [0000] monoglyceride ester of butyric acid 45% diglyceride ester of butyric acid 6% triglyceride ester of butyric acid 1% glycerol 48% [0031] (d) [0000] butyric acid monoglycerides 43% butyric acid diglycerides 6% butyric acid triglycerides 1% glycerol 50% [0032] (e) [0000] monoglyceride ester of propionic acid 49% diglyceride ester of propionic acid 10% triglyceride ester of propionic acid 2% glycerol 39% [0033] (f) [0000] propionic acid monoglycerides 43% propionic acid diglycerides 6% propionic acid triglycerides 1% glycerol 50% [0034] Antibacterial potency values of organic acids alone compared with those of the compositions of the invention are given below in table 1. [0000] TABLE 1 Salmonella Campylobacter E. coli typhimurium jejuni PRODUCT CONC. USED pH (cfu/ml) (cfu/ml) (cfu/ml) Positive control 7 108 × 10 5   120 × 10 5   431 × 10 5   Positive control 4.5 84 × 10 5 96 × 10 5 201 × 10 5   Propionic acid 1:909 7 54 × 10 4 11 × 10 4 33 × 10 3 Propionic acid 1:909 4.5 13 × 10 4 42 × 10 3 14 × 10 1 Butyric Acid  1:1000 7 106 × 10 4   65 × 10 4 18 × 10 3 Butyric Acid  1:1000 4.5 78 × 10 4 25 × 10 3  2 × 10 1 Monopropionin 43 1:109 7 110 × 10 4   12 × 10 3 79 × 10 5 Monobutyrin 43 1:100 7 75 × 10 4 35 × 10 3 48 × 10 4 Monobutyrin 43 1:100 4.5 47 × 10 4  8 × 10 2 87 × 10 3 Note: Monopropionin 43 is composed of: 43% propionic acid monoglycerides 6% propionic acid diglycerides 1% propionic add triglycerides 50% glycerol Note: Monobutyrin 43 is composed of: 43% butyric acid monoglycerides 6% butyric acid diglycerides 1% butyric acid triglycerides 50% glycerol [0035] Table 2 compares the in vitro antibacterial action of pure butyric acid, of butyric acid monoglycerides without free glycerol and of a mixture of butyric acid monoglycerides with free glycerol, against Clostridium perfringens. Whereas the mixture of butyric acid monoglycerides and glycerol already exhibits an inhibitory potency (i.e. no growth) in all three replicates at a concentration of 1000 ppm, the butyric acid monoglycerides do not exhibit any inhibitory potency against the bacterium, and butyric acid only exhibits inhibitory action from 3000 ppm. [0000] TABLE 2 Bacteria: Clostridium perfringens CP27 Inoculation concentration: 10 5 Medium: Brain Heart Infusion Incubation time and appearance of growth; + for 24 hr, ++ for 37 hr and +++ for 96 hr - 3 replications for each concentration Positive Negative control Monobutyrin Butyric acid Control (PC) ppm Butyric Acid 43 monoglycerides +  500 + + + + + + + ++ + + + mean 1000 + no growth + + no growth + + no growth + mean 1500 + no growth + + no growth + + no growth + mean 2000 ++ no growth + ++ no growth + ++ no growth + mean 2500 ++ no growth + ++ no growth + ++ no growth + mean 3000 no growth no growth + no growth no growth + no growth no growth + mean 4000 no growth no growth + no growth no growth + no growth no growth + mean [0036] Table 3 compares the in vitro antibacterial action of pure acetic acid, of acetic acid monoglycerides without free glycerol and of a mixture of acetic acid monoglycerides with free glycerol against porcine Salmonella typhimurium. Whereas the mixture of acetic acid monoglycerides and glycerol (Monoacetin 42) exhibits an inhibitory potency (i.e. no growth) in all three replicates at a concentration of 10,000 ppm, the acetic acid monoglycerides exhibit inhibitory potency against the bacterium from 25,000 ppm and the acetic acid exhibits inhibitory action from 20,000 ppm. [0000] TABLE 3 Bacteria: Porcine Salmonella typhimurium Inoculation concentration: 10 5 Medium: Brain Heart Infusion Incubation time and appearance of growth: + for 24 hr, ++ for 37 hr and +++ for 96 hr - 3 replications for each concentration pH 6 Positive Negative Control Acetic Monoacetin Acetic acid control (PC) ppm acid 42 monoglycerides +  5000 + + + + + + + ++ + + + Mean 10000 + no growth + + no growth + + no growth + Mean 15000 + no growth + + no growth + + no growth + Mean 20000 no growth no growth + no growth no growth + no growth no growth + Mean 25000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean 30000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean 40000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean Note: Monoacetin 42 is composed of: 42% acetic acid monoglycerides 7% acetic acid diglycerides 1% acetic acid triglycerides 50% glycerol [0037] Table 4 compares the in vitro antibacterial action of pure formic acid, of formic acid monoglycerides without free glycerol and of a mixture of formic acid monoglycerides with free glycerol against porcine Salmonella typhimurium. Whereas the mixture of formic acid monoglycerides and glycerol (Monoformin 42) exhibits an inhibitory potency (i.e. no growth) in all three replicates at a concentration of 5,000 ppm, the formic acid monoglycerides exhibit inhibitory potency against the bacterium from 25,000 ppm and formic acid exhibits inhibitory action from 15,000 ppm. [0000] TABLE 4 Bacteria: Porcine Salmonella typhimurium Inoculation concentration: 10 5 Medium: Brain Heart Infusion Incubation time and appearance of growth: + for 24 hr, ++ for 37 hr and +++ for 96 hr - 3 replications for each concentration pH 6 Positive Negative Control Formic Monoformin Formic acid control (PC) ppm acid 42 monoglycerides +  5000 + no growth + + + no growth + ++ + no growth + Mean 10000 + no growth + + no growth + + no growth + Mean 15000 no growth no growth + no growth no growth + no growth no growth + Mean 20000 no growth no growth + no growth no growth + no growth no growth + Mean 25000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean 30000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean 40000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean Note: Monoformin 42 is composed of: 42% formic acid monoglycerides 7% formic acid diglycerides 1% formic acid triglycerides 50% glycerol [0038] Table 5 compares the in vitro antibacterial action of pure fumaric acid, of fumaric acid monoglycerides without free glycerol and of a mixture of fumaric acid monoglycerides with free glycerol (Monofumarin 41) against E. coli. Whereas the mixture of fumaric acid monoglycerides and glycerol exhibits an inhibitory potency (i.e. no growth) in all three replicates at a concentration of 20,000 ppm, the fumaric acid monoglycerides exhibit inhibitory potency against the bacterium from 60,000 ppm and the fumaric acid exhibits inhibitory action from 90,000 ppm. [0000] TABLE 5 Bacteria: E. coli Inoculation concentration: 10 5 Medium: Brain Heart Infusion Incubation time and appearance of growth: + for 24 hr, ++ for 37 hr and +++ for 96 hr—3 replications for each concentration pH 5 Positive Mono- Negative Control Fumaric fumarin Fumaric acid control (PC) Ppm acid 41 monoglycerides + 10000 + + + + + + + ++ + + + Mean 20000 + no growth + + no growth + + no growth + Mean 40000 + no growth + + no growth + + no growth + Mean 60000 ++ no growth no growth ++ no growth no growth ++ no growth no growth Mean 80000 ++ no growth no growth ++ no growth no growth ++ no growth no growth Mean 90000 no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean 100000  no growth no growth no growth no growth no growth no growth no growth no growth no growth Mean Nota: Monofumarin 41 is composed of: 41% fumaric acid monoglycerides 8% fumaric acid diglycerides 1% fumaric acid triglycerides 50% glycerol [0039] If preferred, the compositions of the invention can also contain active principles of essential oils (cinnamic aldehyde, thymol, carvacrol) in percentages comprised between 1 and 20% (calculated by weight on the weight of the mixture of other components) as commonly provided for such products for feeding animals, since these active principles are soluble in lipids but insoluble in glycerol. [0040] It should be noted that when the composition of the invention is dispersed in water, the glycerol surrounds the monoglyceride itself to form drops which incorporate said monoglyceride, they remaining suspended in water (the other optionally added active principles dissolve in the monoglyceride, they also becoming incorporated within the glycerol drop) (see FIG. 1 ). [0041] The compositions of the invention can be prepared according to the usual fatty acid esterification processes amply described in the literature, but using a large excess of glycerol (never less than 200% by weight on the weight of the fatty acids used) in order to obtain a large amount of monoglycerides with large amounts of free glycerol. [0042] The compositions of the invention can be added to the animal feed and/or their drinking water in amounts from 0.1 to 1.5%, preferably from 0.3-0.6% calculated by weight on the feed or drink weight. [0043] The compositions of the invention are particularly indicated for the diets of pigs, chickens, fish, cattle, sheep and companion animals. EXAMPLE 1 [0044] The esterification reaction takes place in batches of 10,000 kg. [0045] 3000 kg of butyric acid and 7000 kg of glycerol are introduced into a reactor at ambient temperature. [0046] The temperature is increased to 140° C., the butyric acid that evaporates being recycled within the reactor by means of a reflux condenser. [0047] The further raising of the temperature from 140 to 170° C. must be very slow (over about 4 hours) and the reflux condenser temperature must be maintained at 120° C. in order to evaporate the water derived from the esterification reaction while the butyric acid continues to recycle within the reactor. [0048] At this point the temperature can be raised to 180° C. (but leaving the reflux condenser temperature at 120° C.) and once this temperature has been reached the acidity of the mixture is expected to reach a value less than 1%. [0049] A vacuum is then applied to distil off any unreacted butyric acid until a final acidity of less than 0.2% is reached. [0050] The mixture is discharged through a cooler to bring it to ambient temperature. [0051] A mixture is thus obtained containing 43% monoglyceride ester, 6% diglyceride ester, 1% triglyceride ester, and 50% glycerol. [0052] Once the esterification reaction is complete the glycerol can be separated if desired by distillation from the thus obtained mono- di- and triglyceride esters to arrive at a 90% monoglyceride concentration. EXAMPLE 2 [0053] Sixty 5 week old DanBred piglets were assigned to two groups of thirty piglets each: A)—control, and B) treated, divided into 6 pens of ten animals each. After the first 10 days of adaptation in the enclosures, all animals were inoculated orally with Salmonella typhimurium, isolated at the Istituto Zooprofilattico of Forli (Italy) from fecal samples of infected pigs, with a dose equal to 7×10 7 cfu. [0054] The following day some of the subjects from each pen presented with diarrhoea. [0055] The symptoms worsened and affected all the subjects over the next three days following infection. [0056] Fecal samples were collected on the third day following infection; the bacterial count was found to be equal to 165,000 cfu in control group A) and 160,000 cfu in the treated group B). Group B) from the third day after infection was treated with a mixture composed of: Butyric acid monoglycerides=45% Butyric acid diglycerides=6% Butyric acid triglycerides=1% Glycerol=48% [0061] administered in the drinking water at a dosage of 0.5% for three days. On the third day after treatment, fecal samples were again collected for bacterial count analysis. The control group A) presented a mean cfu number of 160,000, while in the treated group B) the cfu number was 900. Use of the “butyric acid esters and glycerol” mixture in the stated percentages reduced the cfus of salmonella by 3 log10, with a 3-day administration. This fact confirms the bactericidal effectiveness of the mixture. EXAMPLE 3 [0062] The present field trial was carried out on an Italian farm with hygiene problems such as very evident ileitis resulting from a Lawsonia intracellularis infection, enteritis from Brachyspira Spp and necrotic enteritis resulting from a Treponema hyodysenteriae infection. 1,027 DanBred pigs weighing about 25 kg (71 days old) were divided into two groups: control group A) and treated group B), composed of 511 and 516 animals respectively. [0063] The two groups were fed with a feed that was formulated in identical manner except for the following components: the feed of the control group had added Lincomycin, 200 ppm, and Doxicyclin, 250 ppm, for the first 14 days of the trial, and Lincomycin alone for the remaining time. The treated group B) did not receive antibiotics in the feed, only a “butyric acid esters and glycerol” mixture composed as follows: Butyric acid monoglycerides=45% Butyric acid diglycerides=6% Butyric acid triglycerides=1% Glycerol=48% [0068] administered to the feed in a quantity of 0.5% to replace 0.5% of the soya oil. [0069] The trial lasted 63 days. The growth and feeding efficiency results are summarized in the table below. [0000] TABLE Group B) - Group A) - Butyric acid esters Control and glycerol Delta No. of animals 511 516 Age at the start of the trial 71 71 (days) Age at the end of the trial 134 134 (days) Average weight at the start 25 25 of the trial (kg) Average weight at the end of 62.13 63.61 the trial (kg) No. of dead animals 5 2 −3 No. of rejected animals 3 2 −1 Average daily weight 0.59 0.61 +0.02 increase (kg) Total feed consumed (kg) 53.570 53.250 −320 Meat produced in kg 19.340 20.200 +860 Feed conversion index 2.76 2.64 −0.12 [0070] Although the fecal analysis of the control group A) showed the presence of Lawsonia, its presence was not found in the treated group B). The diarrhoea episodes were also very much reduced in the treated group B). The growth parameters, the feed conversion index of the treated group B) were comparable, and tendentially better than those of the control group A) whose diet contained the aforesaid antibiotics. The “butyric acid esters and glycerol” mixture enabled the highlighted diseases to be controlled, without the use of antibiotics. The trial has demonstrated the antibacterial effect of the “butyric acid esters and glycerol” mixture with a consequent improvement to intestinal health. EXAMPLE 4 [0071] Efficacy Test Towards Salmonella Typhimurium in Chickens [0072] Salmonella Strain [0073] For the test, a strain of Salmonella typhimurium isolated and identified by the IZSLER section of Forli was used. [0074] Animals [0075] SPF (Specific Pathogen Free) chicks were used, 30 animals per test. The chicks were hatched at the IZSLER section of Forli. The subjects were immediately placed into isolation units. [0076] Diet [0077] The animals received water from the mains water supply and a commercial starter ad libitum feed. The feed contained added Monobutyrin 43. [0078] Experimental Protocol [0079] 4 groups of 30 subjects each were prepared. The diets differed by the different amount of Monobutyrin 43 added to the feed from the first day of life, and were identified as follows: untreated control group: 0%, group 1: 1% in the feed, group 2: 0.3% in the feed. Group 3 received the same feed as the control group up to the 14 th day of life, i.e. until the 7 th day post-infection, and only received feed supplemented with 1.4% Monobutyrin 43 after that day. [0080] At aged 7 days, all the subjects were infected by the esophageal route with 10 7 cfu of Salmonella typhimurium. 24 hours following infection, cloacal swabs were taken from all the subjects to confirm that Salmonella typhimurium infection had taken hold. At 14, 24 and 35 days of life, 10 subjects in each group were killed. [0081] The ceca were collected from each animal and the load of Salmonella typhimurium was determined (expressed in cfu/g). [0082] Laboratory Tests [0083] The absence of antibodies against S. typhimurium was confirmed by an ELISA test. The cloacal swabs were seeded directly onto Hektoen Enteric Agar and incubated at 37° C. for 24 hours. One gram of intestinal contents was diluted in 9 ml of Ringer's lactate and seeded onto Hektoen Enteric Agar (inoculum volume: 0.1 ml). Colony counting was carried out after 24 hours of incubation at 37° C. For each collection, the geometric means of the bacterial loads of the 10 killed subjects were calculated. [0084] All the subjects, after one day of life, were found to be seronegative for Salmonella typhimurium. 24 hours after the infection, all the cloacal swabs were found to be positive for S. typhimurium. The results of the determined cecal bacterial loads are shown in the following table. [0000] TABLE CFU in the cecum of chickens infected with Salmonella Typhimurium -10 7 Group 3 Group 1 Group 2 (1.4% in feed (1% in (0.3% from 14 th Control feed) in feed) day of life) Day of infection 0 0 0 0 (7 th day of life) 7 th day post- 6,400,000 770,000 2,226,000 6,302,000 infection Start of treatment 17 th day post- 25,120,000 213,220 1,242,000 171,120 infection 28 th day post- (high >100 300 1,000 infection mortality) EXAMPLE 5 [0085] In Vitro Sensitivity Tests towards Filamentous Fungi (Moulds) [0086] Materials and Methods [0087] Strains of Aspergillus spp, Penicillium spp and Fusarium spp were utilized for the test, having been isolated and identified during diagnostic activity at the IZSLER section of Forli from complete feeds used in the chicken industry. To prepare the inoculum, mycelium of pure cultures of the tested strains was collected using a swab. The material thus collected was dissolved in a culture broth (BHI—Brain Heart Infusion). 5 ml of the fungal suspension and an equal amount of the product to be tested were placed in contact in a test tube. The test tube was incubated at 20±4° C. for 24 hours. [0088] After this time period, the fungal suspension was then seeded and enumerated. [0089] The control suspension was obtained by placing 5 ml of fungal suspension+5 ml of diluent (Ringer's lactate) into a test tube. Reading of the tests was carried out after a 5 day incubation period at 20±4° C. [0090] The results given in the following table are expressed as cfu/ml [0000] TABLE ASPERGILLUS PENICILLIUM FUSARIUM PRODUCT spp. spp. spp: Control 450000 97000 310000 Monopropionin 43 20000 1500 90000 Monobutyrin 43 1000 700 3000 Propionic acid 300 <100 300 Ammonium 1000 100 500 propionate Note: Monopropionin 43 is composed of: 43% propionic acid monoglycerides 12% propionic acid diglycerides 1% propionic acid triglycerides 28% free glycerol 16% H 2 O Note: Monobutyrin 43 is composed of: 43% butyric acid monoglycerides 6% butyric acid diglycerides 1% butyric acid triglycerides 50% glycerol EXAMPLE 6 [0091] In Vitro Efficacy Test towards Penicilium spp and Fusarium spp [0092] Materials and Methods [0093] Strains: strains of moulds isolated and identified by the IZSLER section at Forli were used for the test. The strains were revitalized in BHI broth then enumerated in OGYE agar (after incubation at 20° C. for 5 days) [0094] Substrate: a complete chicken feed, sterilized in a dry oven at 100° C. for 4 hours, was used. [0095] Efficacy test: 10 g of feed were inoculated with 2 ml of fungal suspension (in distilled water) to which 70 μl of the product to be tested was added. The mixture thus obtained was kept at ambient temperature. A positive control (infected and untreated) and a negative control (feed only+distilled water) were also prepared. [0096] On days 7 and 14 following infection, the fungal concentrations in the treated sample and control samples were evaluated. [0097] The results are given in the table below. [0000] TABLE Concentration of Concentration of Concentration of Concentration of Concentration of Concentration of Fusarium spp. Fusarium spp. Fusarium spp. Penicillium spp. Penicillium spp. Penicillium spp. On day 0 7 days post- 14 days post- On day 0 7 days post- 14 days post- PRODUCT (cfu/g) infection (cfu/g) infection (cfu/g) (cfu/g) infection (cfu/g) infection (cfu/g) Positive control 5,700,000 72,000,000 300,000,000 100,000 30,000,000 200,000,000 Negative control <100 <100 <100 <100 <100 <100 Monopropionin 43 5,700,000 410,000 250,000 100,000 <100 <100 Note: Monopropionin 43 is composed of: 43% propionic acid monoglycerides 12% propionic acid diglycerides 1% propionic acid triglycerides 28% free glycerol 16% H 2 O

Described are antibacterial and anti-mould compositions containing high amounts of C 1 to C 7 organic acid mono-glycerides and glycerol, their preparation and their use in animal feedstuffs.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from United States Provisional Patent Application Serial 60/441,097 filed Jan. 17, 2003; the disclosures of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. TECHNICAL FIELD [0003] The invention relates generally to merchandise display systems. More particularly, the invention relates to a merchandise display system that is lockable to prevent the merchandise from being removed. Specifically, the invention relates to such a system wherein merchandise can be handled and viewed by the consumer while remaining locked to thwart shoplifting. [0004] 2. BACKGROUND INFORMATION [0005] In seeking out products to buy, consumers have a natural desire to be able to handle and view the products for making their purchase. However, vendors naturally have a concern that products will be stolen. As a result, vendors desire merchandise displays which are lockable to prevent such theft. The problem that arises is that merchandise display assemblies do not generally allow the consumer to easily handle and view products without the merchandise assembly being unlocked first. [0006] Thus, the art needs a merchandise assembly which is both lockable to prevent theft and also allows the consumer to easily handle and view the product without the need for the vendor to unlock the display assembly until the consumer has already made the decision to purchase the product. The merchandise display assembly of the present invention solves this problem by allowing merchandise to hang from a display rod by a hanging assembly which allows the merchandise to pivot and swivel freely such that the consumer can handle the product and see it from nearly every angle. [0007] U.S. Pat. No. 3,495,716 to Gregory discloses a stereo tape display holder which includes a lockable case to hold the tape, the case having openings in an end wall and side walls thereof through which printed data on the tape may be viewed. A swivel means includes a first annular link coaxially connected to a boss on the case by a bolt or rivet and a second annular link rotatably connected to the first link by a rivet. The second link encircles a rod of a wire display rack sitting atop a display cabinet. The swivel means allows rotation about an axis so that the lockable case is rotatable about said axis with respect to the second link. The rod is freely received by the second link so that the second link may easily slide along and rotate about the rod. This configuration allows the lockable case to be lifted upwardly from the display rack in pivoting relation to the rod and rotated about the axis to facilitate viewing by a consumer. [0008] The configurations disclosed in the Gregory patent leave a variety of areas for improvement. First, the Gregory swivel means rotates about only one axis, so that the swivel means and case must rotate about the rod to allow rotation about a second axis. Applicants' invention, by contrast, includes a swivel which itself allows rotation about first and second axes perpendicular to one another. Thus, Applicants' swivel assembly enhances the ability to maneuver the display case as desired. [0009] Further, the first link of Gregory's swivel means is connected to the display case by a bolt or rivet and the first and second links are attached by a rivet, thus making the case and swivel inseparable, whereas Applicants' invention provides a variety of options whereby the use of a rivet and the like is eliminated and portions of the swivel assembly are separable from one another to allow removal of the display case from the rod assembly. Applicants' ball and socket arrangement requires only two pieces and still provides the additional rotational capability in comparison to the four or more pieces of Gregory's swivel means. The ball and socket configuration provides this simplicity by connecting to the case by a snap fit engagement and linking the two pieces together by interference engagement, thus eliminating separate fasteners. The hinge pin embodiment provides multiple tasking by the hinge pin so that the swivel assembly connects to the case via the hinge pin, rotation about the hinge pin is coaxial with the second axis, and rotation of the display case lid and base occurs about the hinge pin to open and close the display case. Applicants' embodiment using a hanging member, a swivel member and a lower member eliminates need for a boss on the display case, provides a simple snap fit engagement between the hanging and swivel members and provides a snap fit engagement between the swivel and lower members with the latter snap fit providing rotation about the second axis. The various snap fit engagements facilitate assembly of the swivel assembly and the connection to the display case. [0010] As noted above, the Gregory swivel means is configured to be unremovable from the display case and does not permit the display case to be removed from the display rack. Applicants' invention, by contrast, provides a swivel assembly with separable elements which permit the display case to be removed from the rod assembly without unlocking the rod assembly from the support structure, such as a peg board. Thus, after a customer has viewed the item of merchandise while still connected to the rod assembly, a store employee may then easily unlock the display case from the rod assembly to allow purchase of the item. One advantage of this configuration is that the item display case may be removed from the rod assembly without separating the rod assembly from the support structure. Another advantage is that the item may remain in the case until immediately prior to purchase at the cash register, thus providing at least a visual indicator to store or security personnel that the item has not yet been purchased. Additionally, an electronic article surveillance tag may be connected to the display case as opposed to the merchandise, so that an alarm may sound while the item is in the case, but not after it is removed from the lockable display case. [0011] Because Gregory does not include the separable elements noted above, the Gregory device does not need a corresponding locking mechanism. Gregory does disclose locking mechanisms for locking the display case, namely a padlock and a lock with a slidable plunger, but these are standard locks operable with a standard key. Applicants' locking mechanism for holding the separable elements together may be magnetically unlockable and invisible to the eye of a potential thief. The invisibility may prevent a thief from even recognizing that there are separable elements. In addition, the same key may be used for the lock used with the separable elements, the lock used to lock the rod assembly to the support structure and the lock used with the end assembly. [0012] Further, the wire rack display and display cabinet of Gregory have several limitations. First, Gregory's wire display rack is bulky and cumbersome even if not attached to the display cabinet. When attached atop the boxlike display cabinet, the display support structure is particularly cumbersome if not stationary and certainly consumes a great deal of space. In addition, the wire rack is configured in a shelf-like fashion whereby the display cases rest upon one or more wires while attached via the swivel means to the rod. [0013] By contrast, Applicants' rod assemblies are simple and compact, and are thus easily manufactured at a relatively low cost and consume far less precious floor space. Applicants' rod assemblies are easily attachable to support structures such as peg boards and are lockable to such structures to prevent the entire rod assembly and merchandise from being rapidly removed. Rod assemblies are provided which either attach at both ends to the support structure (including the U-shaped embodiment) or include an end assembly, each option configured to prevent unauthorized removal of merchandise from the rod assemblies while permitting easy loading of merchandise thereon. In addition, Applicants' rod assemblies are easily movable and are removable from the support structure to allow reuse of the rod assemblies elsewhere and facilitate reorganization upon the support structure as needed. [0014] Gregory's display case uses walls having openings therein to permit a consumer to view printed material on the merchandise stored therein. Gregory's case also provides a partition wall spaced from one of the walls, the partition wall intended to make the case fit a smaller item of merchandise and being removable in a breakaway fashion to allow the case to fit a larger item. Applicants' display case fully encloses an item of merchandise, thus providing better protection from vandalism and accommodating a variety of sizes of items to be displayed therein without the need for such a partition wall. In addition, Applicants' transparent case offers visibility from all sides without concern for creating wall openings, which must be particularly sized to securely retain the merchandise and simultaneously allow visibility of pertinent indicia on the merchandise. BRIEF SUMMARY OF THE INVENTION [0015] The invention generally provides a system for securely displaying merchandise in a manner that allows customers to handle and view the merchandise without removing the merchandise from a display case. The invention provides different interchangeable display configurations that allow a customer to handle, pivot, and rotate a secured item of merchandise. [0016] In one embodiment, the present invention provides a merchandise display system that includes a display structure; a swivel assembly rotatable about a first axis and rotatable about a second axis substantially perpendicular to the first axis; the swivel assembly adapted to be connected to the display structure; and a display case adapted to carry an item of merchandise; the display case being connected to the swivel assembly so that the display case is rotatable about the first and second axes. [0017] In another embodiment, the present invention provides a merchandise display system that includes a display structure; a first member and a swivel member rotatably connected to the first member about a first axis; the first member being adapted to be connected to the display structure; a display case having a pair of members selectively lockable to one another and being adapted to carry an item of merchandise; and at least one hinge pin having a longitudinal second axis substantially perpendicular to the first axis and rotatably connecting the swivel member to the display case about the second axis so that the display case is rotatable about the first and second axes; the at least one hinge pin rotatably connecting the display case members to one another about the second axis whereby the display case members are rotatably movable between open and closed positions when unlocked. [0018] In another embodiment, the present invention provides a merchandise display system having a display structure; a first member, a swivel member and a U-shaped lower member having a pair of legs extending from an intervening base; the swivel member being rotatably connected to the first member about a first axis by a snap fit engagement; the first member being adapted to be connected to the display structure; a display case adapted to carry an item of merchandise; the display case defining a pair of spaced holes on one end thereof and being lockable to selectively retain or release the item of merchandise; and the lower member base being disposed within the display case and the lower member legs respectively extending through the holes in the display case so that the lower member supports the display case and the lower member legs rotatably connect the lower member to the swivel member by a snap fit engagement about a second axis substantially perpendicular to the first axis so that the display case is rotatable about the first and second axes. [0019] The invention also provides an embodiment wherein a display rod is locked at both of its ends to a display structure. The display rod is adapted to carry items of merchandise. [0020] The invention also provides an embodiment wherein a connector is snap fit to a display case in a one-way snap fit connection. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0021] [0021]FIG. 1 is a side elevational view of the first embodiment showing the merchandise display system of the present invention. [0022] [0022]FIG. 2 is a fragmentary exploded perspective view of the first embodiment showing the various members of the hanging assembly and the display case. [0023] [0023]FIG. 3 is a fragmentary perspective view of the first embodiment of the hanging assembly and display case. [0024] [0024]FIG. 4 is a fragmentary partial sectional view of the first embodiment of the hanging assembly and the display case. [0025] [0025]FIG. 5 is a fragmentary perspective view of the first embodiment showing the display case and hanging assembly hanging from the lower rod in a display position. [0026] [0026]FIG. 6 is a fragmentary perspective view of the first embodiment similar to FIG. 5 with the hanging assembly and display case in a partially rotated position. [0027] [0027]FIG. 7 is a fragmentary perspective view of the first embodiment similar to FIGS. 5 and 6 showing the display case and hanging assembly in a further rotated position. [0028] [0028]FIG. 8 is a fragmentary side elevational view of the first embodiment showing the display case rotated upwardly from the display position (shown in phantom lines). [0029] [0029]FIG. 9 is a fragmentary side elevational view of the first embodiment similar to FIG. 8 showing the door of the display case being opened and the merchandise being removed from the display case. [0030] [0030]FIG. 10 is a side elevational view of a second embodiment of the present invention. [0031] [0031]FIG. 11 is a fragmentary exploded view of the second embodiment showing the hanging assembly and display case. [0032] [0032]FIG. 12 is a perspective view of the second embodiment showing the hanging assembly and display case. [0033] [0033]FIG. 13 is a fragmentary partial sectional view of the second embodiment showing the hanging assembly and the display case. [0034] [0034]FIG. 14 is a fragmentary side elevational view of the second embodiment showing a display case rotated upwardly from a display position (shown in phantom lines). [0035] [0035]FIG. 15 is a fragmentary side elevational view of the second embodiment showing the display case in an open position with the item of merchandise being removed therefrom. [0036] [0036]FIG. 16 is a side elevational view of a third embodiment of the present invention. [0037] [0037]FIG. 17 is a fragmentary exploded view of the third embodiment showing the hanging assembly and display case. [0038] [0038]FIG. 18 is a fragmentary perspective view of the third embodiment showing the hanging assembly and display case. [0039] [0039]FIG. 19 is a partial sectional view showing the display case and hanging assembly including a locking device in a locked position. [0040] [0040]FIG. 20 is a side elevational view of the third embodiment including an alternate rod assembly and one display case in a rotated position. [0041] [0041]FIG. 21 is a top plan view of the third embodiment as shown in FIG. 20. [0042] [0042]FIG. 22 is a fragmentary partial sectional view of the third embodiment showing the rod assembly, display case and hanging assembly including a magnetic key and the locking device in an unlocked position. [0043] [0043]FIG. 23 is a fragmentary exploded partial sectional view of the third embodiment as shown in FIG. 22 wherein the locking device is unlocked and in a released position. [0044] [0044]FIG. 24 is a side elevational view of a fourth embodiment of the present invention. [0045] [0045]FIG. 25 is a fragmentary exploded perspective view of the fourth embodiment showing the hanging assembly and display case. [0046] [0046]FIG. 26 is a fragmentary partially exploded perspective view of the fourth embodiment showing the hanging mechanism intact and showing how the locking tabs of the mechanism insert into the slots in the display case. [0047] [0047]FIG. 27 is a partial sectional view of the fourth embodiment as viewed from the side showing the hanging assembly in a position prior to being inserted into the slots in the display case. [0048] [0048]FIG. 28 is a view similar to FIG. 27 with the hanging assembly connected to the display case. [0049] [0049]FIG. 29 is a fragmentary perspective view similar to FIG. 26 showing the hanging assembly connected to the display case. [0050] [0050]FIG. 30 is a fragmentary partial sectional view of the fourth embodiment taken on line 30 - 30 of FIG. 28. [0051] Similar numbers refer to similar parts throughout the specification. DETAILED DESCRIPTION OF THE INVENTION [0052] A first embodiment of the merchandise display system of the present invention is indicated generally at 100 and is shown in FIGS. 1-9. Display system 100 includes a lockable rod assembly 102 , a hanging assembly 104 which hangs from rod assembly 102 and a lockable merchandise display case 106 which is connected to and hangs from hanging assembly 104 . Hanging assembly 104 is configured to allow display case 106 and merchandise 122 within to pivot and swivel in a manner such that the consumer can easily handle case 106 and view merchandise 122 within case 106 . [0053] Lockable rod assembly 102 includes an inner end 108 which is lockable to a peg board 110 or the like. Inner end 108 may also be securely fixed to a wall or other type of display unit. Rod assembly 102 includes lockable base assembly 109 adjacent inner end 108 . Rod assembly 102 further includes an upper rod 112 and a lower rod 114 which are substantially parallel and extend outwardly and horizontally from inner end 108 to an outer end 116 . Inner rod assembly 102 further includes a locking mechanism 118 adjacent outer end 116 , the locking mechanism locking onto rod 114 to prevent removal of merchandise from lower rod 114 . One embodiment of a rod assembly that may be used is more fully described in U.S. Pat. No. 6,474,478 granted to Huehner et al. on Nov. 5, 2002, and said patent is incorporated herein by reference. [0054] Display case 106 includes an interior chamber 120 in which is inserted an item of merchandise 122 . Display case 106 includes a front side 119 , a back side 121 , and a pair of lateral sides 123 . Display case 106 further includes an upper end 124 and a lower end 126 . A lockable door 128 is hingedly connected to case 106 by hinge 130 adjacent lower end 126 . Case 106 also includes an upper wall 132 adjacent upper end 124 in opposed relation to door 128 . Upper wall 132 defines a pair of slots 134 for receiving a portion of hanging assembly 104 as described below. Any of a variety of known lockable cases may be used as display case 106 . [0055] In accordance with the present invention, hanging assembly 104 includes a hanging member 136 , a swivel member 138 , a U-shaped lower member 140 and a cap 142 . Hanging member 136 has an upper portion 144 which defines a hole 146 for receiving lower rod 114 . Hanging member 136 further includes a lower portion 148 which includes a pair of downwardly extending spaced prongs 150 each of which includes a neck 152 , a shoulder 154 extending outwardly from neck 152 and a surface 156 which tapers downwardly and inwardly from shoulder 154 . [0056] Swivel member 138 defines a vertical hole 158 for receiving prongs 150 of hanging member 136 . Swivel member 158 further includes shoulders 160 (FIG. 4) which separate a cylindrical upper chamber 162 and a cylindrical lower chamber 164 of hole 158 , the upper chamber having a smaller diameter than the lower chamber. Hole 158 is configured to receive prongs 150 of hanging member 136 such that shoulders 160 and shoulders 154 engage one another in a snap fit engagement which prevents removal of hanging member 136 from swivel member 138 . Tapered surfaces 156 facilitate in section of prongs 150 into hole 158 . Cap 142 covers lower chamber 164 of hole 158 and may do so by snap fit engagement or be secured in another manner known in the art. Swivel member 138 has ends 166 , from each of which extend downwardly an inner tab 168 and an outer tab 170 opposed to one another in spaced relation to define a slot 172 . Outer tab 170 defines a horizontal hole 173 . [0057] U-shaped lower member 140 includes a substantially flat and rectangular base member 174 from which extend upwardly a pair of spaced tabs 176 in opposed relation to one another. Each tab 176 has an outer surface 178 from which extends a dome-shaped knob 180 . Base member 174 of lower member 140 is configured to be positioned in interior chamber 120 of display case 106 adjacent upper wall 132 to provide the connection of member 174 to case 106 . Tabs 176 of member 140 extend through slots 134 in upper wall 132 of display case 106 and into slots 172 of swivel member 138 . Knobs 180 slide into respective holes 173 in outer tabs 170 to form a snap fit engagement. An axis 182 extends vertically through hole 158 of swivel member 138 and also between prongs 150 of hanging member 136 . An axis 184 passes through knobs 180 , as shown in FIG. 8. [0058] In operation, hanging assembly 104 allows display case 106 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 122 encased therein. FIGS. 5-9 indicate the various positions of the case and show its maneuverability and overall use. As seen in FIG. 5, hanging assembly 104 is in a display position as it ordinarily would be for display purposes as it hangs from lower rod 114 of rod assembly 102 . In this position, swivel member 138 and display case 106 are situated substantially normal to lower rod 114 as viewed from above. FIG. 6 shows hanging assembly 104 along with display case 106 in a position rotated approximately 90° from the position shown in FIG. 5 about axis 182 . In this position, swivel member 138 and display case 106 are situated substantially parallel to lower rod 114 as viewed from above. Swivel member 138 swivels about axis 182 as supported by shoulders 160 resting on shoulders 154 of prongs 150 . The diameter of upper chamber 162 of hole 158 is large enough to allow chamber 162 to rotate about neck 154 of prongs 150 while the diameter of lower chamber 164 likewise allows rotation about tapered surfaces 156 of prong 150 . Cap 142 functions to prevent tampering with prongs 150 by a shoplifter attempting to break prongs 150 or disengage them from within hole 158 . The display position of FIG. 5 shows upper wall 132 , front side 119 and lateral sides 123 . FIG. 6, like FIG. 5, continues to show upper wall 132 and the same lateral side 123 , but in the 90° swivelled position also shows back side 121 of case 106 . [0059] [0059]FIG. 7 shows hanging assembly 104 and display case 106 rotated approximately 180° from the display position shown in FIG. 5. Thus, FIG. 7 shows back side 121 and upper wall 132 along with the other lateral side 123 of display case 106 . The rotational movement of swivel member 138 allows swivel member 138 and display case 106 to rotate 360° about axis 182 , thereby allowing all sides of display case 106 and merchandise 122 encased therein to be seen by consumers. Because a plurality of items of merchandise 122 are displayed within respective cases 106 hanging from lower rod 114 , ordinarily the simple rotational movement allowed by swivel member 138 may not be sufficient to allow a consumer to view all the sides easily due to interference of such movement by the other cases 106 . This difficulty is resolved by the additional ability of hanging assembly 104 to pivot upwardly as shown in FIG. 8. [0060] More particularly, lower member 140 is configured to rotate about axis 184 which passes through knobs 180 . Tabs 176 of lower member 140 move freely within slots 172 defined by swivel member 138 and knobs 180 move freely within respective holes 173 . However, the snap fit engagement of knobs 180 into holes 173 is sufficiently secure to prevent removal by a shoplifter or make such removal rather difficult. The rotational motion about axis 184 allows display case 106 to travel an arc of at least 180° in the direction between inner end 108 and outer end 116 of rod assembly 102 , limited only by interference with lower rod 114 , locking mechanism 118 , base assembly 109 , peg board 110 , or any other display cases 106 hanging from rod 114 . Referring back to the position shown in FIG. 6, the rotational motion indicated in FIG. 8 from the position shown in FIG. 6 would allow case 106 to be moved in a far broader arc approaching that of a full circle, limited only by the interference with upper rod 112 and other such members. The overall movement allowed by the rotation about axes 182 and 184 allows display case 106 to be maneuvered in nearly any position so that item of merchandise 122 can be easily viewed and relevant information read from all sides of said item. The overall movement of display case 106 is also facilitated and enhanced by the fact that hanging assembly 104 is able to rotate about lower rod 114 . FIG. 9 shows display case 106 rotated upwardly towards outer end 116 of rod assembly 102 . Further, lockable door 128 is shown in an open position after rotating about hinge 130 . Finally, item of merchandise 122 is shown being removed from case 106 . [0061] Thus, merchandise display system 100 provides a secure system by which items of merchandise 122 are encased in display cases 106 which have lockable doors 128 to prevent merchandise 122 from being removed without authorization. Further, system 100 prevents unauthorized removal from lower rod 114 of hanging assembly 104 and display case 106 hanging therefrom. System 100 also allows the consumer to maneuver display case 106 with item of merchandise 122 therein to easily view merchandise 122 without the need for removal from rod 114 . Thus, system 100 provides security for the seller as well as convenient review of merchandise 122 for the consumer. [0062] A second embodiment of the merchandise display system of the present invention is indicated generally at 200 and is shown in FIGS. 10-15. Display system 200 includes a lockable rod assembly 202 , a hanging assembly 204 which hangs from rod assembly 202 and a lockable merchandise display case 206 which is connected to and hangs from hanging assembly 204 . Hanging assembly 204 is configured to allow display case 206 and merchandise 222 within to pivot and swivel in a manner such that the consumer can easily handle case 206 and view merchandise 222 within case 206 . [0063] Lockable rod assembly 202 includes an inner end 208 which is lockable to a peg board 210 or the like. Rod assembly 202 includes lockable base assembly 209 adjacent inner end 208 . Rod assembly 202 further includes an upper rod 212 and a lower rod 214 which are substantially parallel and extend outwardly and horizontally from inner end 208 to an outer end 216 . Inner rod assembly 202 further includes a locking mechanism 218 adjacent outer end 216 , the locking mechanism locking onto rod 214 to prevent removal of merchandise from lower rod 214 . Rod assembly 202 is more fully described in U.S. Pat. No. 6,474,478, as noted above. [0064] Display case 206 includes an interior chamber 220 in which is inserted an item of merchandise 222 . Display case 206 includes a front side 219 , a back side 221 , and a pair of lateral sides 223 . Display case 206 further includes an upper end 224 and a lower end 226 . Unlike display case 106 , display case 206 does not have a lockable door adjacent the lower end. Instead, display case 206 includes an inner shell 228 and an outer shell 229 which rotate about a pair of common hinge pins 230 (FIG. 11) between a closed position (FIG. 14) and an open position (FIG. 15), the inner shell and outer shell being lockable in the closed position. [0065] In accordance with the present invention, hanging assembly 204 includes a hanging member 236 , a swivel member 238 , hinge pins 230 and a cap 242 . Hanging member 236 has an upper portion 244 which defines a hole 246 for receiving lower rod 214 . Hanging member 236 further includes a lower portion 248 which includes a pair of downwardly extending prongs 250 each of which includes a neck 252 , a shoulder 254 extending outwardly from neck 252 and a surface 256 which tapers downwardly and inwardly from shoulder 254 . [0066] Swivel member 238 defines a vertical hole 258 for receiving prongs 250 of hanging member 236 . Swivel member 258 further includes shoulders 260 (FIG. 13) which separate a cylindrical upper chamber 262 and a cylindrical lower chamber 264 of hole 258 , the upper chamber having a smaller diameter than the lower chamber. Hole 258 is configured to receive prongs 250 of hanging member 236 such that shoulders 260 and shoulders 254 engage one another in a snap fit engagement which prevents removal of hanging member 236 from swivel member 238 . Tapered surface 256 facilitates in section of prongs 150 into hole 258 . Cap 242 covers lower chamber 264 of hole 258 and may do so by snap fit engagement or be secured in another manner known in the art. Swivel member 238 has ends 266 and a pair of arms 268 extending downwardly adjacent respective ends 166 . Arms 268 define a pair of respective horizontal holes 273 which are substantially in alignment with one another and also configured to align with hinge holes 231 formed in inner shell 228 and hinge holes 233 formed in outer shell 229 of display case 206 . Hinge pins 230 are inserted in hinge holes 231 and 233 and into hole 273 in arms 268 , thereby allowing for rotational movement about axis 235 (FIG. 13), which extends through hinge pins 230 . This rotational movement may be accomplished, for example, by the diameters of hinge holes 233 of outer shell 229 forming a snug fit with hinge pins 230 while hinge holes 231 of inner shell 228 and holes 273 of arms 268 are large enough to permit a rotational movement of hinge pins 230 . [0067] In operation, hanging assembly 204 allows display case 206 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 222 encased therein. FIGS. 5-7 showing the first embodiment of the present invention are generally applicable as to the movement of the second embodiment as well, and in combination with FIGS. 14-15, indicate the various positions of the case and show its maneuverability and overall use. Hanging assembly 204 functions in the same manner as hanging assembly 104 in regard to the rotational or swiveling properties as viewed from above, as described in regard to assembly 104 above. [0068] Like assembly 104 , hanging assembly 204 pivots upwardly as shown in FIG. 14. While the same motion is allowed, assembly 204 utilizes a different configuration to achieve that effect. More particularly, with hinge pins 230 inserted into hinge holes 231 and 233 of display case 206 and holes 273 of arms 268 , display case 206 is able to rotate about axis 235 with respect to swivel member 238 . The maneuverability of display case 206 about axis 235 is essentially the same as display case 106 about axis 184 . Further, the overall maneuverability of display case 206 is substantially the same as that of case 106 , as described above. [0069] [0069]FIG. 15 shows display case 206 rotated upwardly towards outer end 216 of rod assembly 202 . FIG. 15 also shows display case 206 in an open position. Display case 206 differs from case 106 in that display case 206 includes an inner shell 228 and an outer shell 229 that pivot with respect to one another about axis 235 with the use of hinge pins 230 . FIG. 15 further shows item of merchandise 222 being removed from case 206 . Inner shell 228 and outer shell 229 may be locked to one another in a closed position (FIG. 14) to prevent unauthorized removal of merchandise 222 . [0070] Thus, merchandise display system 200 provides a secure system by which items of merchandise 222 are encased in display cases 206 which have lockable inner and outer shells 228 and 229 to prevent merchandise 222 from being removed without authorization. Further, system 200 prevents unauthorized removal from lower rod 214 of hanging assembly 204 and display case 206 hanging therefrom. System 200 also allows the consumer to maneuver display case 206 with item of merchandise 222 therein to easily view merchandise 222 without the need for removal from rod 214 . Thus, system 200 provides security for the seller as well as convenient review of merchandise 222 for the consumer. [0071] A third embodiment of the merchandise display system of the present invention is indicated generally at 300 and is shown in FIGS. 16-23. Display system 300 includes a lockable rod assembly 302 , a hanging assembly 304 which hangs from rod assembly 302 and a lockable merchandise display case 306 which is connected to and hangs from hanging assembly 304 . Hanging assembly 304 is configured to allow display case 306 and merchandise 322 within to pivot and swivel in a manner such that the consumer can easily handle case 306 and view merchandise 322 within case 306 . [0072] Lockable rod assembly 302 includes an inner end 308 which is lockable to a peg board 310 or the like. Rod assembly 302 includes lockable base assembly 309 adjacent inner end 308 . Rod assembly 302 further includes an upper rod 312 and a lower rod 314 which are substantially parallel and extend outwardly and horizontally from inner end 308 to an outer end 316 . Inner rod assembly 302 further includes a locking mechanism 318 adjacent outer end 316 , the locking mechanism locking onto rod 314 to prevent removal of merchandise 322 from lower rod 314 . Rod assembly 302 is the same as assemblies 102 and 202 . [0073] Display case 306 includes an interior chamber 320 in which is inserted an item of merchandise 322 . Display case 306 includes a front side 319 , a back side 321 , and a pair of lateral sides 323 . Display case 306 further includes an upper end 324 and a lower end 326 . A lockable door 328 is hingedly connected to case 306 by hinge 330 . Case 306 also includes an upper wall 332 adjacent upper end 324 in opposed relation to door 328 . Upper wall 332 defines a pair of slots 334 for receiving a portion of hanging assembly 304 as described below. [0074] In accordance with the present invention, hanging assembly 304 includes a hanging member 336 , a swivel member 338 , a U-shaped lower member 340 and a cap 342 . Hanging assembly 304 allows case 306 to be removed from rod assembly 302 when a lock is unlocked. The key that unlocks this lock may be the same key that unlocks rod assembly 302 . Hanging member 336 includes an upper member 341 and a lower member 343 . Upper member 341 of hanging member 336 has an upper portion 344 which defines a hole 346 for receiving lower rod 314 . A cylinder 345 defining an interior chamber 347 (FIG. 22) extends downwardly from upper portion 344 of upper member 341 . Cylinder 345 has a lower end 337 and defines an annular recessed area 339 adjacent lower end 337 . Recessed area 339 is part of interior chamber 347 . Lower member 343 includes a lower portion 348 and a generally cylindrical rod 349 extending upwardly therefrom. Rod 349 defines a notch 351 extending lengthwise on one side of rod 349 . An annular flange 357 complementary to recessed area 339 extends radially outward from rod 349 below notch 351 . A plate spring 353 is disposed within interior chamber 347 of cylinder 345 to one side of chamber 347 . In an assembled form, rod 349 of lower member 343 is disposed within interior chamber 347 of cylinder 345 with annular flange 357 disposed within recessed area 339 in a snap-fit engagement. In a locked position (FIG. 19), plate spring 353 is partially disposed within notch 351 and engages an upper portion of rod 349 . FIG. 22 shows hanging assembly 304 in an unlocked position wherein a magnetic key 355 attracts the portion of plate spring 353 which was disposed within notch 351 in the locked position so that plate spring 353 lies flat outside the bounds of notch 351 . [0075] Swivel member 338 , cap 342 and U-shaped lower member 340 are identical to their counterparts in the first embodiment as described above. However, in accordance with the present invention, FIGS. 20 and 21 show an alternate embodiment of a lockable rod assembly 303 . Rod assembly 303 includes a pair of ends 305 which may be fixed to a display or which can be locked in a lockable base assembly 307 connected to a peg board 309 or the like. At least one base assembly 307 is configured to allow upper portions 344 to be placed on the rod when assembly 307 is unlocked. [0076] In operation, hanging assembly 304 functions in the same manner as hanging assembly 104 of the first embodiment, except for the removably connected upper and lower members 341 and 343 of hanging member 336 and the locking mechanism created by upper member 341 , lower member 343 and plate spring 353 . In addition, the maneuverability of display system 300 is altered somewhat by the use of the alternate U-shaped lockable rod assembly 303 , as described below. [0077] When rod 349 is disposed in interior chamber 347 with flange 357 forming a snap-fit engagement with recessed area 339 , flange 357 supports the lower portions of hanging assembly 304 along with display case 306 and merchandise 322 . However, this snap-fit engagement still allows reasonably easy removal of rod 349 from interior chamber 347 when hanging assembly 304 is in the unlocked position. [0078] The locking mechanism of hanging member 336 functions as follows. Rod 349 is inserted into interior chamber 347 of cylinder 345 so that the inwardly extending portion of plate spring 353 is depressed outwardly until notch 351 aligns with said portion of plate spring 353 , thereby allowing said portion of plate spring 353 to move inwardly into notch 351 and engage an upper portion of rod 349 , to prevent removal of rod 349 from interior chamber 347 of cylinder 345 . To unlock the locking mechanism, magnetic key 355 is placed against cylinder 345 adjacent plate spring 353 to attract the inwardly disposed portion of plate spring 353 , thus removing said portion of plate spring 353 from within notch 351 , as shown in FIG. 22. Rod 349 may be removed from interior chamber 347 , as shown in FIG. 23. This allows the lower portion of hanging assembly 304 to be removed along with display case 306 and item of merchandise 322 as desired. This gives an alternative method of removing display case 306 from rod 314 or rod assembly 303 without having to unlock the rod assembly itself. [0079] As viewed from above, U-shaped lockable rod assembly 303 allows for similar movement as with rod assembly 302 , which as noted above, is the same as assemblies 102 and 202 . However, the maneuverability of display case 306 hanging from rod assembly 303 is not limited by an upper rod or a locking mechanism at the end of an upper and lower rod as is the case with rod assembly 302 . Similar to rod assembly 302 , assembly 303 would be limited by any additional display cases 306 hanging from rod assembly 303 . However, maneuverability would also be limited by a peg board 309 or the like. Nonetheless, display case 306 is able to rotate in a 360° arc as viewed from above and also may rotate about axis 384 such that it may travel an arc of at least 180° in a direction between a pair of ends 305 of rod assembly 303 . [0080] Thus, merchandise display system 300 provides a secure system by which items of merchandise 322 are encased in display cases 306 which have lockable doors 328 to prevent merchandise 322 from being removed without authorization. Further, system 300 prevents unauthorized removal from lower rod 314 of hanging assembly 304 and display case 306 hanging therefrom. Assembly 300 also allows the consumer to maneuver display case 306 with item of merchandise 322 therein to easily view merchandise 322 without the need for removal from rod 314 . Thus, system 300 provides security for the seller as well as convenient review of merchandise 322 for the consumer. [0081] A fourth embodiment of the merchandise display system of the present invention is indicated generally at 400 and is shown in FIGS. 24-30. Display system 400 includes a lockable rod assembly 402 , a hanging assembly 404 which hangs from rod assembly 402 and a lockable merchandise display case 406 which is connected to and hangs from hanging assembly 404 . Hanging assembly 404 is configured to allow display case 406 and merchandise 422 within to pivot and swivel in a manner such that the consumer can easily handle case 406 and view merchandise 422 within case 406 . [0082] Lockable rod assembly 402 is the same as rod assembly 102 and functions in the same manner. In addition, display case 406 is similar to display case 106 except that upper wall 432 , instead of defining a pair of slots, defines a pair of holes 434 . As viewed from above, holes 434 are substantially shaped like a cross-section of a light bulb wherein there is a circular portion 433 with a U-shaped portion 435 extending outwardly therefrom. [0083] In accordance with the present invention, hanging assembly 404 includes a hanging member 436 and a swivel member 438 . Hanging member 436 has an upper portion 444 which defines a hole 446 for receiving lower rod 414 . Upper portion 444 also includes a pair of ears 445 extending outwardly therefrom. Hanging member 436 further includes a lower portion 448 which includes a downwardly extending neck 452 from which extends downwardly a spherical member 450 . [0084] Swivel member 438 defines a vertical cylindrical hole 458 for receiving spherical member 450 of hanging member 446 . Hole 458 is bounded by cylinder 447 having an upper end 449 and a lower end 451 . Hole 458 is narrowed adjacent upper end 449 of cylinder 447 by inwardly extending annular flange 453 . A pair of wings 455 extend horizontally outwardly from cylinder 447 adjacent lower end 451 . A pair of ribs 457 extend outwardly in a vertical plane from cylinder 447 and upwardly from respective wings 455 . A pair of spaced locking tabs 459 extend downwardly from respective wings 455 . As shown in FIGS. 26-28, each locking tab includes a neck 461 extending downwardly from respective wing 455 and a substantially circular foot 463 connected to neck 461 there below. In relation to neck 461 , foot 463 extends toward front side 419 of display case 406 when swivel member 438 is connected thereto, and foot 463 also extends laterally toward lateral sides 423 of case 406 . Each locking tab 459 also includes a finger which extends downwardly from respective wing 455 and outwardly from respective neck 461 away from the forward extension of foot 463 such that finger 465 extends toward back side 421 of display case 406 when swivel member 438 is installed thereon. [0085] In assembling hanging assembly 404 , upper portion 444 of hanging member 436 is inserted upwardly through hole 458 of swivel member 438 so that upper portion 444 is disposed above cylinder 447 and spherical member 450 rests against annular flange 453 . The distance defined by the outermost portions of ears 445 is larger than the diameter defined by the innermost portion of annular flange 453 . Ears 455 nonetheless slide past flange 453 so that during assembly ears 445 prevent hanging member 436 from slipping back through hole 458 before hanging member 436 is hung on lower rod 414 of rod assembly 402 . The diameter of spherical member 450 is wide enough to prevent spherical member 450 from being pushed upwardly beyond annular flange 453 , but is small enough to allow easy movement within hole 458 of cylinder 447 . [0086] Locking tabs 459 form a locking engagement with display case 406 when inserted properly into holes 434 . FIGS. 26-28 indicate how locking tabs 459 are inserted into holes 434 . First, each foot 463 is aligned with and inserted into a respective circular portion 433 of hole 434 . Each foot 463 is then slid toward front side 419 of case 406 so that each neck 461 fits into a respective U-shaped portion 435 . Simultaneously, each finger 465 slides along upper wall 432 until it snaps downwardly into a respective circular portion 433 of hole 434 . Once in this configuration, as shown in FIG. 28, locking tabs 459 form a locking engagement with case 406 . [0087] In operation, hanging assembly 404 allows display case 406 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 422 encased therein. Hanging assembly 104 functions somewhat similarly to the previous embodiments in that it allows for substantially the same type of movement. Particularly, assembly 404 and case 406 may be rotated 360° about vertical axis 482 . In addition, the ball and socket configuration of assembly 404 allows swivel member 438 and display case 406 to pivot upwardly in any direction from axis 482 . While this upward movement is multi-directional, it is more limited than in the previous embodiments. The limiting factor is an interference between annular flange 453 or upper end 449 of cylinder 447 and neck 452 of hanging member 436 as swivel member 438 and display case 406 are moved in an upward direction. Nonetheless, with the additional mobility provided by rotational movement of hanging member 436 about lower rod 414 , display case 406 may be maneuvered sufficiently to view any side of display case 406 without difficulty. [0088] Thus, merchandise display system 400 provides a secure system by which items of merchandise 422 are encased in display cases 406 which have lockable doors 428 to prevent merchandise 422 from being removed without authorization. Further, system 400 prevents unauthorized removal from lower rod 414 of hanging assembly 404 and display case 406 hanging therefrom. System 400 also allows the consumer to maneuver display case 406 with item of merchandise 422 therein to easily view merchandise 422 without the need for removal from rod 414 . Thus, system 400 provides security for the seller as well as convenient review of merchandise 422 for the consumer. [0089] In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. [0090] Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.

A merchandise display system includes a rod lockably connected to a peg board, a hanging member hanging from the rod and a swivel member rotatably connected to the hanging member about a first axis. The swivel member is connected to a lockable display case for carrying an item of merchandise and is rotatable about a second axis perpendicular to the first axis. Thus, the display case is rotatable about the first and second axes to facilitate viewing the merchandise from any angle while the case is lockably connected to the rod. The hanging and swivel members may be a ball and socket combination. Alternately, the swivel member may connect to the display case via a hinge pin about which portions of the case may rotate to open and close. Alternately, a lower member may extend from within the case through holes therein to rotatably connect to the swivel member about the second axis.

CROSS REFERENCE TO REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application 62/253,681 entitled “Post-Tensioning Apparatus and System for Structures” filed on Nov. 11, 2015, the entire contents of which are incorporated herein by reference in its entirety for all purposes. FIELD OF THE INVENTION [0002] The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended. BACKGROUND OF THE INVENTION [0003] The field of concrete installation and maintenance, particularly surrounding structural or load bearing concrete, requires site preparation and formula of mix to create the desired preparation. Although mechanically strong in compression, concrete is relatively weak in tensile and bending loads and is subject to cracking and breakage under such conditions. [0004] Practices including techniques of post-tensioning, which involves the pre-stressing of steel tendons within the concrete form to account for its relative weakness in tension. This practice is often used in installation for purposes such as commercial and residential construction where beams, floors and bridging components must span a length exceeding longer than practical with ordinary reinforced concrete. [0005] Although the practice of post-tensioning aims to pre-load concrete and place it under a resting compressive load to counteract tensile and bending loads to mitigate mechanical failures. However, uncontrollable variables such as frost heaving, ground movement, erosion, water infiltration and others compromise the structural integrity of concrete and can cause cracking and mechanical failure of the structure of the concrete installation. [0006] Due to the costly or nature or logistical impossibility of the replacement of concrete installations, many solutions aim to repair concrete after mechanical failure. Although it may seem sensible to replace a concrete installation in some situations, it will be appreciated that even the wholesale demolition and reinstallation of the concrete may not guarantee against failure in the future. [0007] Cracks in concrete are caused due to the mechanical failure of the concrete in a localized area due to a possible variety of problems with the installation. For this reason, tensioning may be desired in scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed. Post-tensioning typically involves preloading of a metal structure prior to adding more concrete to reinforce the repair. SUMMARY OF THE INVENTION [0008] Some solutions aim to fill the crack with a bonding adhesive or cement to repair the concrete. However, the lack of strength afforded by cements, often referred to as hydraulic cement, proves problematic. When considering the structural integrity of a concrete installation, the cost of repeated failure depends upon the application of the concrete. And cement patches have a high risk of repeated failure due to weak bond and structural integrity of the cement. [0009] Other solutions to the mechanical failure of concrete resulting in cracks is addressed through internal metal stitching as proposed by U.S. Pat. No. 5,476,340, ('340), and U.S. Pat. No. 5,771,557, ('557), incorporated herein by reference, to Contrasto. Constrasto '340 discloses a method surrounding the use of apparatus '557 to bridge a crack using a series of cuts across a crack, inserting metal structure, and making additional cuts across the previous cuts and metal structure to add cross structure in the form of metal brackets prior to the addition of filler material. Contrasto '340 fails to provide any method of tension application to the concrete. [0010] Constrasto '557 aims to provide increased localized tensile strength for the concrete around a crack. The higher ductility of steel as compared to concrete does not prevent the movement of the concrete beyond a failure threshold and therefore cannot prevent further cracking in the localized region and Contrastro '557 fails to provide the ability to pre-tension the structure or provide post-tensioning to the concrete structure. [0011] Some solutions aim to address failed concrete by placing devices across cracks due to mechanical failure in efforts to provide post-tensioning by preloading metal members spanning across the crack. These metal members comprise plates with a post at either distal end affixed to one side that are inserted into pre-drilled apertures for anchoring. The metal members are then tensioned using wedge or cam based mechanisms to tension the metal member after the posts have been inserted into the concrete. These tensioning mechanisms, however, are limited in travel. If the apertures created for the posts are spaced too far apart, the user may not be able to install the metal member. If the apertures created for the posts are too close together, the user may not be able to tension the metal member as prescribed. [0012] The present invention relates to a post-tensioning apparatus and system providing functionality of post-tensioning to existing structures. The present disclosure relates to the repair of concrete structures but is not limited to such application. Embodiments of the invention permit the application and adjustment of a modular post-tensioning apparatus including at least two attachment features interconnected by at least one tensioning mechanism. The modularity of the apparatus surrounds the ability to select and use different attachment features based upon the location, substrate, desired tensioning properties and other relevant variables in the tensioning of a structure. [0013] In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, where it is desired to provide post structural reinforcement. [0014] Embodiments of the apparatus provide tensile strength across a mechanical failure zone without further tensioning of the apparatus. However, tensioning the apparatus preloads the apparatus to resolve tolerances or gaps between the apparatus and the points of application within a structure to which it is applied. Tensioning the apparatus also places the apparatus in tension and compresses the structure between attachment features applied to the structure. This also mitigates tensile forces bearing on the concrete, as concrete is typically weaker in tension than in compression. [0000] Certain embodiments of the present invention comprise at least two tension application components interconnected by one tensioning mechanism. Once the tension application components are applied to the structure, the tensioning mechanism is actuated to apply a tensile load to the tension application components, placing the apparatus in a tensile state. [0015] Tension application components translate forces from the tensioning mechanism to the structure by attaching to the structure, such as a concrete installation. Each tension application component may also be attached to one or more application points. These application points may be on a singular structure or spanning two separate structures. It will be appreciated that the tension application components may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments, the apparatus permits modular use of a variety of tension application components where the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form. It will be further appreciated that application points may comprise apertures in the structure, other features within the concrete or hardware pre-affixed to the concrete. [0016] In certain embodiments, a tensioning mechanism comprising two axially aligned threaded female features, one having standard clockwise threading and the opposing exhibiting counter-clockwise threading, is referred to as a turnbuckle. In such an embodiment, the tension application components have a cylindrical cross-section with a length of screw threading at a proximal end to engage with the threaded female features of the tensioning mechanism. Furthermore, the distal section of the tension application component has as bend, which provides a post-like form to allow the application of force upon an existing structure. A structure may also be prepared by creating an aperture in the structure where one can place the tension application component to apply force on the structure. [0017] It will be appreciated that a tensioning mechanism may comprise a turnbuckle. The tensioning mechanism may also comprise a rotational device with a set of indexed features radially around the rotational device in which a pawl, cog, or tooth engages to allow motion in one direction only, such as a ratchet, or a geared mechanism such as a rack-and-pinion or worm gear. [0018] Certain embodiments of the present invention are directed to the repair of a concrete structure where a fissure or crack has occurred. The surface is prepared by creating plurality of apertures with at least one aperture being on a first side of a fissure or crack, and at least one aperture being on a second side of a fissure or crack. The apertures are positioned at a distance that generally corresponds to the length of the apparatus prior to actuation of the tensioning mechanism which shortens the apparatus. The distal ends of first and second tension application components are then inserted into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism, creating post-tensioning in the area surrounding the crack or fissure. [0019] In certain embodiments, a tension application component is used to apply a tensile load across a portion of a structure. The tension application component comprises an attachment end configured to engage with a tensioning mechanism. The attachment end engages the tensioning mechanism at a proximal end of the tensioning application component. The distal end of the tension application component has a feature such as an aperture or hook-form configured to engage with features installed in the structure. Such features which include, but are not limited to a post or rebar affixed to the structure. [0020] Certain embodiments of the present invention comprise a tensioning application component that engages with the tensioning mechanism. The proximal end of the tension application component has an attachment feature configured to engage with the tensioning mechanism. The distal end of the tension application component is configured to engage the apertures within a prepared surface or extents of an existing structure with a plurality of post-like features. Having a plurality of post-like features distributes the load of the tensioning apparatus across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus with structures having limited structural stability rather than an apparatus with a more concentrated loading which may risk further damage to the structure to be repaired. A scenario in which a user may want to use more than one post-tensioning apparatus, the plurality of post-like features allows the use of fewer post-tensioning apparatuses over a given length of a fissure or crack to achieve stronger structural stability. [0021] Certain embodiments have a tension application component. In certain embodiments, the tension application component comprises a plate-form. The plate-form affixes to a structure to apply tensile load to the structure at the desired location. The plate-form can be affixed by welding or using at least one threaded fastener, masonry anchor or other methods known to those skilled in the art. The plate-form may further comprise a fixation point such as a loop or hook to allow the engagement of a tension application component. It may be desired to affix the plate-form to the structure using a plurality of fasteners or anchors to distribute tensile loading across a larger area of concentration on the structure. This distributed loading can also provide tensile strength between independent structures where other types of tension application components cannot. In contrast, post-like forms create a higher localized concentration of stress. Furthermore, the use of plate-forms may allow the post-tensioning between adjacent structures that are not coplanar such as adjacent planar structures disposed at not offer the necessary structural stability to provide tension between independent structures. [0022] In certain embodiments, a tension application component has a plate-form having at least one aperture. The tension application component includes an engagement feature extending outward from the surface of the plate-form. The engagement features can engage with a tensioning mechanism, including through the use of a threaded male component, the threaded male component typically being axially parallel to the bore of the aperture in the plate-form. In such an embodiment, a tension application component can be attached to a first surface at an angle, typically orthogonal, and attached to a second surface. This allows post-tensioning across a crack or fissured that has occurred proximal to a corner where two sections of a structure meet at an angle. [0023] Certain embodiments of the present invention comprise a tension application component having at least two parallel post structures. The two parallel post structures are disposed at an angle from a connecting body. The tension application component has an aperture, located medial to the post structures. The aperture is also typically axially parallel to the post structures. The tension application component distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, the tension application component has a post feature attached to a tensioning mechanism, where the post feature is disposed through the medially located aperture. [0024] In certain embodiments of the invention, the apparatus comprises a tensioning mechanism having a consistent cross-sectional profile. The tensioning mechanism can have female threaded features at its distal ends. The threaded receptacles have opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features. [0025] In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square. [0026] In certain embodiments, the external profile of the tensioning device has a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form. The external profile may be used for the application of torque with a tool such as a wrench or other standard torque applying tool. [0027] In certain embodiments, the tensioning mechanism has at least one aperture. The aperture passes through the tensioning mechanism perpendicular to central axis of the mechanism typically intersecting the central axis. The aperture allows for torque application through the use of a rod or other shaft-like object inserted into the aperture. After torque application it may be desired to dispose a rod in the aperture to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism is applied. It will be appreciated by those skilled in the art that such apertures are typically in a medial section of the tensioning mechanism. Furthermore, it may be desired to have a plurality of apertures. The additional apertures can be angularly displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism in tighter locations. The apertures may be coplanar to the axis of the central axis. In certain embodiments, the apertures may be located on offset yet parallel planes that are perpendicular to the central axis of the tensioning mechanism. [0028] Embodiments of the present disclosure may be used in a system comprising at least one tensioning mechanism and at least two tension application components. Furthermore, different tensioning components may be used interchangeably with a tensioning mechanism to allow system customization for each application. BRIEF DESCRIPTION OF FIGURES [0029] FIG. 1A —A top view of a post tensioning system [0030] FIG. 1B —A side view of a post tensioning system [0031] FIG. 2 —A side view of a turnbuckle embodiment of a tensioning mechanism [0032] FIG. 3 —A side view of a tension application component [0033] FIG. 4A —A side view of a tension application component [0034] FIG. 4B —A top view of a tension application component [0035] FIG. 5A —A top view of a post tensioning system [0036] FIG. 5B —A side view of a post tensioning system [0037] FIG. 6A —A perspective view of a tension application component [0038] FIG. 6B —A top view of a tension application component [0039] FIG. 6C —A side view of a tension application component [0040] FIG. 7A —A top view of a post tensioning system [0041] FIG. 7B —A side view of a post tensioning system [0042] FIG. 8A —A bottom view of a tension application component [0043] FIG. 8B —A side view of a tension application component [0044] FIG. 8C —A top view of a tension application component [0045] FIG. 9A —A perspective view of a post tensioning system [0046] FIG. 9B —A side view of a post tensioning system [0047] FIG. 9C —A front view of a post tensioning system [0048] FIG. 10A —A side view of a tension application component [0049] FIG. 10B —A top view of a tension application component [0050] FIG. 11 —A perspective view of a tension application component DETAILED DESCRIPTION [0051] In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, wherein it is desired to provide structural reinforcement. Tensioning may be desired in many scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed. [0052] An apparatus 100 , as shown in FIGS. 1A and 1B , embodying the inventive principles of the invention comprises at least two tension application components 101 a and 101 b and one tensioning mechanism 102 disposed and attached therebetween. When the tension application components 101 are constrained, the actuation of the tensioning mechanism 102 applies tensile force to the tension application components 101 resulting in placing the apparatus in a tensile state. Certain embodiments of such an apparatus may comprise an overall length of 30.5 cm (12 in). [0053] The tension application component 101 translates forces from the tensioning mechanism 102 to the structure by attaching to a structure, such as a concrete installation. The tension application component 101 may also be attached to two or more independent elements or structures. It will be appreciated that the tension application components 101 may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments the apparatus 100 permits modular use of a variety of tension application components wherein the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form. [0054] In certain embodiments of the apparatus, as shown in FIG. 2 , a tensioning mechanism 102 comprises two axially aligned threaded female features, 201 a and 201 b , having opposing threading at first and second distal ends of the tensioning mechanism 102 . For instance, an embodiment of a tensioning mechanism 102 may comprise 201 a having standard clockwise threading and the 201 b having counter-clockwise threading. This configuration of tensioning mechanism 102 is commonly referred to as a turnbuckle. In certain embodiments a tensioning mechanism 102 comprises a length of 10.2 cm (4.0 in) and diameter of 15.875 mm (0.625 in) In such an embodiment the tension application components 101 a and 101 b , as shown in FIG. 3 , have a cylindrical profile with a length of screw threading, 301 a and 301 b , at a proximal end 302 to engage with the threaded female features, 201 a and 201 b , of the tensioning mechanism 102 . Furthermore, the distal section 303 of the tension application component has a bend which provides a post-like form 304 to allow the application of force upon an existing structure or aperture prepared in a structure for the placement of the tension application components 101 a and/or 101 b . It will be appreciated that the bend in the tension application components 101 a and/or 101 b may comprise a plurality of angular bends typically totaling at least 90-degrees. In certain embodiments the female threaded features as illustrated by FIG. 2 , the threaded female features 201 a and 201 b have screw threading having a lead of 1.5875 mm (0.0625 in) and a diameter of 9.525 mm (0.375 in). It will be appreciated to those skilled in the art that lead, surrounding male threaded features, indicates the axial travel for a single revolution of the screw thread. In such an embodiment, the screw threading 301 a and 301 b , seen in FIG. 3 , also have screw threading having a lead of 1.5875 mm (0.0625 in). Such embodiments may be designated with ANSI thread designation as ⅜-16 per ANSI/ASME B1.1-1989 (R2001). Certain embodiments of a post-like form 303 as seen in FIG. 3 , comprises a length of 44.45 mm (1.75 in) and diameter of 9.525 mm (0.375 in). It will be appreciated that other embodiments may have post-like forms of different lengths. It will be appreciated that a tension application component 303 , shown to have a matching cross-section to the male threaded features 301 a and 301 b , are not limited to a round cross-section or dimensions matching that of the male threaded features 301 a and 301 b . It will be further appreciated that the threading associated with the male threaded features 301 a and 301 b , seen in FIG. 3 , and the female threaded features 201 a and 201 b may comprise threading larger or smaller than embodiments described herein. Certain embodiments of a tension application feature 101 a and 101 b may comprise a length of 12.7 cm (5.0 in). [0055] It will be appreciated by those skilled in the art that a post-tensioning device may be made of a steel alloy designated as a hot rolled and proof stressed alloy steel conforming to ASTM A722 CAN/CSA (G279-M1982). It will be further appreciated that certain embodiments may be made of a steel allow such as AISI 1144, sometimes referred to by an associated trade name of Stressproof®. AISI 1144 steel is appreciated to those skilled in the art as a is a carbon-manganese grade steel which is severely cold worked to produce high tensile properties. [0056] Certain embodiments such as those shown in FIGS. 1A-3 are directed to the repair of a concrete structure where a fissure or crack has occurred due to mechanical failure. The surface is prepared by placing apertures in the concrete on either side of the fissure or crack. The apertures are positioned at a distance that generally corresponds to the the length of the apparatus 100 with attached tension application components 101 a and 101 b prior to actuation of the tensioning mechanism 102 which shortens the mechanism. The distal end 303 of tension application components 101 a and 101 b , such as the those shown in FIG. 3 , into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism 102 to creating post-tensioning in the area surrounding the crack or fissure. [0057] In certain embodiments of the apparatus as shown in FIGS. 4A-5C , a tension application component 401 applies tensile load across a desired structure. The tension application component 401 comprises an attachment feature 402 at a proximal end 403 for engaging with a tensioning mechanism and an aperture 404 . The distal end 405 has a tension application feature 404 , such as an aperture or hook-form, configured to engage with features installed in the structure. Such features include, but are not limited to, a post or rebar, affixed to the structure. [0058] Certain embodiments of the invention, as shown in FIGS. 6A, 6B, 7A, 7B and 7C , comprise a tension application component 601 that engages with a tensioning mechanism 102 . A proximal end 603 of the tension application component 601 has an attachment feature 602 configured to engage with the tensioning mechanism 102 . The distal end 605 of the tension application component 601 is configured to engage the apertures of a prepared surface or the edges of an existing structure by having a plurality of post-like features 604 . Having a plurality of post-like features 604 distributes the load of the tensioning mechanism 102 across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus 601 in conjunction with structures that cannot offer structural stability for an apparatus with a more concentrated loading. Certain embodiments of a tension application component 601 as seen in FIG. 6A-C has a two parallel post-like features 604 interconnected such that the post like features are separated by a distance of 8.89 cm (3.5 in). In the scenario which a user may want to use more than one post-tensioning apparatus 601 , the plurality of post-like features 604 allows the use of fewer post-tensioning apparatuses 601 over a given length of a fissure or crack to achieve stronger structural ability. Certain embodiments of an aperture 404 as seen in FIG. 4 , comprise a length of 19.05 mm (0.75 in) and width of 12.7 mm (0.5 in). Certain embodiments of a tension application feature 405 as seen in FIGS. 4A and 4B has a length of 59.18 mm (2.33 in), width of 31.75 mm (1.25 in) and thickness of 9.525 mm (0.375 in). [0059] Certain embodiments have a tension application component. Such as those shown in FIGS. 8A, 8B, 8C, 9A, 9B and 9C , a tension application component 801 comprises a plate-form 802 , the plate-form 802 having at least one aperture 803 . The plate-form 802 affixes to a structure, typically using at least one aperture 803 in the plate-form 802 . The plate-form 802 may be affixed to the structure through an aperture 803 . Fixation strategies include the use of threaded features, masonry anchors and other methods known to those skilled in the art. This allows the application of tensile load to the structure at the desired location. The plate-form 802 further comprises and engagement features, such as a threaded male component 804 extending outward from the surface of the plate-form, typically axially parallel to the bore of an aperture in the plate-form. This engagement feature is configured to engage with a tensioning mechanism 102 . In such an embodiment, a tension application component 801 can be attached to a first surface at an angle to, typically orthogonal, and attached to a second surface. This allows post tensioning across a crack or fissure that has occurred proximal to a corner where two surfaces of the structure or adjacent structures meet at an angle. It will be appreciated to those skilled in the art that a plurality of apertures 803 may be used to affix the plate-form 802 to the structure. The use of a plurality of apertures 803 in conjunction distributes the load born by the fixation features. Certain embodiments of a plate-form 802 has a length of 12.7 cm (5.0 in), width of 31.75 mm (1.25 in) and thickness of 6.35 mm (0.25 in). In such embodiments, a plate-form 802 further comprises a male threaded component 804 disposed centrally to the width of the plate-form and 8.255 mm (0.325 in) from a longitudinal end of the plate-form, extending orthogonally from the plate-form. [0060] Certain embodiments of the invention, as shown in FIGS. 10A and 10B , comprise a tension application component 1001 having at least two parallel post structures 1002 . The two parallel post structures 1002 are disposed at an angle from a connecting body 1003 . The tension application component 1001 has an aperture 1004 located medial to the post structures 1002 . The aperture 1004 is also typically axially parallel to the post structures. The tension application component 1001 distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, a second tension application component, such as 101 a in FIG. 3 , has a post feature attached to a tensioning mechanism, where the post-feature 304 is disposed through the medially located aperture 1004 . Certain embodiments of a tension application component as seen in FIG. 10B comprises a medially located aperture 1004 in a medially mounted tab 1005 affixed to the tension application component. In such embodiments, a medially located aperture 1004 comprises a width of 12 mm (0.473 in) and length of 12.7 mm (0.5 in), the medially mounted tab 1005 having a length and width of 25.4 mm (1.00 in), and the tension application component having an overall length of 30.5 cm (12.0 in). [0061] Certain embodiments have a tension application component. In certain embodiments of, as shown in FIG. 11 , the tension application component comprises a plate-form 1102 . The plate-form 1102 affixes to a structure to apply tensile load to the structure at the desired location. The plate-form 1102 can be affixed by masonry anchors or threaded features through apertures 1103 in the plate-form 1102 , welding or other methods known to those skilled in the art. The plate-form 1102 further comprises a fixation point 1104 configured to engage through a secondary tension application component, such as having a loop, hook, post-like feature or aperture. In the case of the plate-form 1102 being fixated through the use of a plurality of fasteners or anchors, this distributes any tensile loading applied to the fixation point such as when applying post-tensioning across a fissure or crack. The distributed load can also provide tension between independent structures where other types of tension application components cannot. For example, post-like forms create a higher localized concentration of stress and do not offer the necessary structural stability to provide tension between independent structures. [0062] In certain embodiments of the invention such as that shown in FIG. 2 , the apparatus comprises a tensioning mechanism, the tensioning mechanism 102 having consistent cross-section. The tensioning mechanism 102 can have female threaded features, 201 a and 201 b , at its distal ends. The threaded receptacles, 201 a and 201 b , having opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism 102 when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features. [0063] In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by to applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square. [0064] In certain embodiments the tensioning mechanism 102 , such as that shown in FIG. 2 , has at least one at least one torque application aperture 202 . The torque application aperture 202 , passes through the tensioning mechanism perpendicular to the central axis of the mechanism typically intersecting the central axis of the tensioning mechanism 102 . The torque application aperture 202 allows for torque application through the use of a rod or other shaft-like object. After torque application, it may be desired to dispose a rod in the torque application aperture 202 to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism 102 is applied. It will be appreciated to those skilled in the art, that apertures 202 are typically be in a medial section of the tensioning mechanism 102 . Furthermore, it may be desired to have a plurality of apertures. The additional apertures 202 can be radially displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism 102 in tighter locations. The apertures 202 may be coplanar to the axis of the central axis. In certain embodiments, the apertures 202 may be located on offset yet parallel planes perpendicular to the axis of the central axis of the tensioning mechanism 102 . [0065] In certain embodiments, the external profile of a tensioning device comprises a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form, wherein the external profile may be used for the application of torque with a tool such as a wrench or other standard torque tool. [0066] Embodiments of the invention disclosed herein may be used in a system comprising at least one tensioning mechanism and at least two tension application components wherein the tensioning components are interchangeably with a tensioning mechanism to allow system customization for each application. In such an embodiment of a system the tension application components may have a threading to match the tensioning mechanism with right-hand or left-hand threads alternatively. It will be appreciated that a system comprising at least one tensioning mechanism and at least two tension application components may comprise a first tension application component of a first type and a second tension application component of a second type. [0067] In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of and claims priority to Patent Cooperation Treaty Application No. PCT/EP2015/060034, filed on May 7, 2015, which claims priority to German Application No. DE 10 2014 106 596.4 filed on May 9, 2014, each of which applications are hereby incorporated herein by reference in their entireties. BACKGROUND [0002] Means for fastening bellows produced from elastomer materials, in particular pleated bellows and roller bellows, are well known. Thus, for some time so-called mutually overlapping retaining straps have been available that attain a clamping effect by tautening the two free strap ends with suitable means. However, the pleated bellows can be damaged in the region of the free strap ends, and the latter also require considerable space for installation. A number of so-called endless annularly closed clamping rings have therefore been suggested in the past. Their diameter is reduced by crimping, i.e., by radial compression by means of suitable tools, so that during the crimping process a bellows is ultimately securely held on a fastening body, for instance, a joint housing or a shaft. [0003] To produce such endless annularly closed clamping rings, it is known to roll tape pieces trimmed from an endless tape material and butt-weld them to one another perpendicular to the center line of the ring, but this technique is very time-consuming. In contrast, instead of such welding, known from DE 40 21 746 A1 is providing on the first and second free ends of a tape segment outside and inside closure strips that are embodied complementary to one another and have undercut regions so that, when the closed connection is under tensile load, inwardly directed forces that permit a point connection of the two complementary closure strips act on the outer closure straps. An end region may be embodied, for instance, such that an essentially T-shaped head piece is embodied thereon, while the second end region complementary hereto provides a jaw-shaped fork adapted to the first end region, the two end regions linearly butting and engaging one another. A plurality of dovetail or T-shaped strips may also be provided on the ring width. Such endless annularly closed tensioning rings described in DE 40 21 746 A1 have become known as such with a so-called puzzle lock. However, it is a disadvantage of the endless tensioning ring known from DE 40 21 746 A1 that these can open occasionally, whether during transport to the consumer or user of the closed endless tensioning rings, or whether during use of the latter, for instance for retaining pleated bellows or roller bellows on outer joint housing parts or shafts. There is therefore a need for fasteners that have improved closure of the two free ends of a strip-like segment for forming an endless tensioning ring. SUMMARY [0004] Disclosed herein is a fastener, in particular for bellows, comprising a male end segment and a female end segment complementary to the male end segment, as well as the use thereof for fastening bellows on joint housings and/or shafts, which fastener has an improved closing behavior. The fastener has at least one undercut region being embodied in the male end segment. [0005] The fastener, in particular for bellows, comprises a male end segment and a female end segment complementary to the male end segment, each having at least a first transversal undercut region, and wherein a first width b 1 of the male end segment is determined either by the minimum width b 1 of a first foot segment extending away from a first base in the first male transversal undercut region, or, if there is a recess that is arranged displaced beyond the base in a length direction of the fastener, by minimum widths b 11 and b 12 of longitudinal segments in the region of the recess, and wherein the female end segment has a first and a second outer longitudinal segment, each having a second minimum width b 21 and b 22 in the region of the first female transversal undercut and, possibly, having an innerly disposed transversal undercut region with a second foot segment, wherein the latter extends away from a second base and has a third minimum width b 3 in the innerly disposed transversal undercut region, wherein b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ) is in a range from approximately 0.79 to approximately 1.27. [0006] The specific cross-sectional width ratios help to ensure that, given the many stresses to which the fastener is exposed during use, it experiences only slight crack formation between the contact surfaces of the male and female end segments so that the service life in use is extended. Apart from the claimed ranges for the cross-sectional width ratio b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ), wherein b 3 is only to be taken into consideration if there is an innerly disposed transversal undercut region, analyses of a number of generic fasteners using finite element methods have found the occurrence of transversal crack formations, that is, those transverse to a longitudinal extension of the fastener, especially immediately adjacent to an outer wall of the fastener. These occur in particular when there is tensile-bending strain. With the present fastener, these crack formations are significantly reduced or do not occur. [0007] Both the male and the female end segments may have a first transversal undercut region, but they may also each additionally have a second or third or fourth transversal undercut region. The number of transversal undercut regions in the male end segment and in the female end segment is always equal. The possibly present at least one innerly disposed transversal undercut region of the male end segment likewise has a counterpart in an innerly disposed transversal undercut region of the female end segment. It is possible that exactly one innerly disposed transversal undercut region is present in the female end segment and in the male end segment. In the context of the present application, a first transversal undercut region relative to the male and female segments shall be construed to mean the transversal undercut region next to the base of the male segment, wherein in the case of the female end segment this refers to the fastener being in the closed condition. Alternatively, with respect to the female segment when the fastener is in the open condition, the first transversal undercut region may be defined as the undercut region next to an end of the female end segment. The end of the female end segment is associated with the base of the male end segment in the closed condition or is immediately adjacent thereto. If only one transversal (outer) undercut region is provided in the male and female end segments, therefore just a first undercut region for each, these are associated with one another when the fastener is in the closed condition. In contrast, if more than one transversal male and female undercut regions are provided, they are not associated with one another. For instance, in this case the first male transversal (outer) undercut region is associated with the second female transversal (outer) undercut region. There are the same number of male and female transversal (outer) undercut regions. [0008] With respect to determining the cross-sectional width ratios as disclosed and/or claimed herein, there is a first, second, third, and fourth stage depending on the first, second, third, fourth, etc. transversal undercut regions. The first stage relates to the first transversal undercut regions of the male and female end segments, the second stage relates to the second transversal undercut regions of the male and female end segments, the third stage relates to the third transversal undercut regions of the male and female segments, the fourth stage relates to the fourth transversal undercut regions of the male and female segments, etc. [0009] When the present disclosure addresses an inner or interiorly disposed (transversal) undercut region, this means an undercut region that is formed exclusively using the embodiments of the male and female end segments, and has neither a direct transversal nor a direct longitudinal undercut with respect to an outer wall of the fastener. In this context, transversal means that undercuts are embodied transverse to a length direction of the fastener, the term “transverse” here encompassing not only transversal undercuts that run at a right angle to the outer wall of the fastener, but also those that run at an angle with respect to the outer wall of the fastener. In this context, longitudinal means that undercuts run in the length direction of the fastener, “length direction” meaning that they may run both approximately parallel to the outer wall of the fastener and at an angle thereto. The inner undercut region also has transversal undercuts, but these are formed in recesses of the female and/or male end segment and therefore do not relate to the outer wall of the fastener. [0010] For an interiorly disposed undercut region, it is always necessary for at least one recess to be provided in a center element, arranged in the male or female end segment, in which a complementary center element of the female or male end segment may engage. In the context of the present disclosure, more than one inner undercut region, for instance two or three undercut regions, may also be provided. [0011] The male segment may be considered as provided with a tongue-like projection. The latter has at least one foot part and at least one head part arranged thereon, wherein the head part, in the case of the male end segment, has first and second extensions that project beyond an outer contour of the foot part. The example of the female end segment with an interiorly disposed undercut region may also be considered mushroom-shaped or the like with respect to the foot segment with a head part, or may also be considered tongue-like. However, the extension of this tongue or this mushroom head in the length direction of the fastener is at most approximately 50% of that of the tongue-like projection of the male end segment, possibly between approximately 15% and approximately 42%. The foot segment with head part, arranged approximately centrally in the female end segment, may be considered to be a projection, especially a mushroom head-shaped projection, arranged on the base of the female end segment. This projection is possibly arranged on the base with longitudinal segments of the female end segment adjacent on both sides. The projection may project over the longitudinal segments in the length direction of the fastener or may be arranged within one of these defined spaces. The mushroom head-shaped projection of the female end segment is possibly arranged or arrangable inside the male end segment in a recess of the latter when the fastener is in the closed condition. Apart from any overcuts provided in edge areas for better connection when closed, an outer contour of the mushroom head-shaped projection of the female end segment essentially corresponds to an inner contour of the male end segment. A recess in the male end segment is arranged in a center element for forming an inner undercut region, possibly in a head part arranged there. The means for forming an inner undercut region on the male end segment possibly has a foot part that carries the head part with the recess. The head part possibly projects beyond the foot part, forming two extension parts. The recess is possibly provided between them. Outer or first, second, third, fourth, etc. transversal (outer) undercut regions shall be understood in the context of the present invention to be those regions that, with respect to the male end segment, are those undercuts that are transversal or longitudinally directly relative to the outer wall of the fastener. [0012] In the present disclosure, when an inner undercut region and at least one first outer or transversal undercut region are mentioned, undercut regions that have transversal undercuts are meant. Transversal undercuts in the context of the present disclosure are oriented transverse in any direction of the fastener apart from a length direction. They are possibly formed from linear and/or curved segments, frequently having different radii. [0013] The inner undercut region and the at least one outer or transversal undercut region extend in the length direction of the fastener, possibly between minimum widths, relative to the specific undercut regions, of the center elements arranged in the male and female end segments. For instance, an inner undercut region of the female end segment extends proceeding from the minimum width b 3 of the foot segment of the female end segment to the minimum widths b 61 and b 62 of the two extension parts of the head part of the male end segment. For instance, a first outer or transversal undercut region extends approximately between a region of minimum width b 1 of the first foot segment that is arranged on the first base of the male end segment to approximately a minimum width b 21 and b 22 of two longitudinal segments of the complementary female end segment, arranged on both sides of a second foot segment of the female end segment that is arranged centrally on the second base. [0014] Alternatively or additionally, the reason for the improved statically dynamic behavior is also the provision of the foot segment with the head part, which is arranged approximately in the center in the female end segment and which can be engaged in the male end segment embodied complementary thereto. A corresponding recess is provided there through which an inner undercut region is embodied in the male end segment. In addition to the inner undercut region, the male end segment has at least one outer or transversal undercut region. A female end segment in the context of the present disclosure describes such an undercut region, which receives a male end segment and is primarily lateral. [0015] The subject matter of the present disclosure is alternatively or additionally a fastener of the type cited above, a female end segment comprising a base on which is arranged a foot segment arranged approximately centrally there, on which is arranged a head part that projects laterally over an outer contour of the foot segment transverse and, seen in a transverse direction of the fastener, comprising lower lateral surfaces for embodying at least one inner undercut region in a recess of the male end segment. Both examples of the fastener, which may also be cumulative, are improvements with regard to both static and dynamic loads compared to those from the prior art. [0016] The disclosed fastener is possibly embodied in a ribbon-like form. It is produced in this shape and then bent to create a closed ring. In one example, therefore, the claimed fastener may be closed to create a closed ring, and especially may be embodied as a closed ring, the complementary male and female end segments being connected to one another. It may be advantageously provided that the male or female end segment may have material overcuts, especially in their respective head parts, but also in the foot part, wherein overcuts means material overcuts, so that when the ribbon-like fastener is closed to create a closed ring, deformations due to material overlays occur in these regions. Due to this, in regions in which cracks may be formed when the fastener is in use and are very highly stressed, this crack formation may be prevented so that the service life of the fastener embodied as a closed ring is extended in the fastening condition. [0017] By bending the strip-like fastener to create a closed ring and also by crimping for fastening, for instance, a bellows with the fastener on a shaft, for instance, forge deformations and/or other deformations of the male and female end segments occur. Therefore, in the present disclosure, when reference is made to geometric values, value-related terms such as parallel, etc., or value ranges such as for instance angles or radii, these references relate to the ribbon-like fastener, that is, not to the closed fastener. The minimum widths are generally approximately retained in a closed and crimped fastener. [0018] In the present disclosure, when the term “approximately” is used in reference to concrete values, value-related terms like parallel, etc. or ranges of values, these shall be construed to include such deviations as the person skilled in the art considers to be normal in the field of the technical expert, especially deviations of +/−10% of the specific value or term, possibly +/−5% of the specific value or value-related term. [0019] In one example of the fastener, the widths b 1 or (b 11 +b 12 ) and (b 21 +b 22 ) together are at least 38%, possibly at least 40%, of a total width b of the fastener. The aforesaid widths are possibly approximately 38% to approximately 80%, possibly approximately 40% to approximately 75%, of the total width b of the fastener. A longitudinal force acting on the fastener can be transferred best to the center element of the male and female end segment, especially to the male foot segment, with the ratios or ranges provided above. [0020] In another example, arranged in at least one transversal undercut region are notch radii of at least approximately 0.3 mm, possibly of at least approximately 0.5 mm, and possibly particularly in a range from approximately 0.3 mm to approximately 0.9 mm. In a further example, another notch radius of a maximum of approximately 0.3 mm is associated with a notch radius of at least approximately 0.3 mm. Particularly possible in the context of the present invention, provided in the at least one transversal undercut region are notch radii of approximately 0.4 mm to approximately 0.9 mm, and associated with these are a further notch radius of approximately 0.2 mm to approximately 0.35, possibly of approximately 0.2 mm to approximately 0.3 mm. In another example of the present invention, a notch radius is at least approximately 0.3 mm, possibly at least 0.5 mm, and possibly in a range from approximately 0.4 mm to approximately 0.85 mm in the transition from the first base of the male end segment to the foot segment. Here, as well, different radii may possibly be used, as described in the foregoing. [0021] Notch radii of at least approximately 0.3 mm, possibly at least approximately 0.5 mm, and more possibly particularly in a range from approximately 0.3 mm to approximately 0.9 mm are arranged in the region between lateral longitudinal surfaces of the foot segment and lateral transverse surfaces of the extension parts of the male end segment. It may advantageously be provided that different radii are used, wherein in the region of the minimum width b 1 of the foot segment of the male end segment greater notch radii in a range from approximately 0.7 mm to approximately 0.9 mm are advantageously provided, to which are connected minimum radii in a range of approximately 0.25 mm to approximately 0.5 mm, possibly in a range from approximately 0.3 mm to approximately 0.4 mm. [0022] In one particularly example of the present invention, provided in the region of minimum widths of the first, second, third, fourth, etc. transversal undercut regions or innerly disposed transversal undercut regions are the greatest possible notch radii, in particular those in a range from approximately 0.5 mm to approximately 0.9 mm, particularly possibly those in a range from approximately 0.6 mm to approximately 0.9 mm, to which are connected minimum notch radii in a range of approximately 0.2 mm to approximately 0.35 mm. This advantageously suppresses the static or dynamic load-related widening of cracks and the like in the undercut regions of the inventive fastener that are critical for load transfer. [0023] The first foot segment on the first base of the male end segment possibly has a greater width b 4 than the first minimum width b 1 . It is furthermore possible that a transition angle γ (gamma) is between the first base and the first foot segment of the male end segment in a range from approximately 90.5° to approximately 110°, possibly in a range from approximately 91° to approximately 102°. Using this specific example of the first foot segment of the male end segment it is advantageously possible to realize the greatest possible notch radii in critical regions, especially in regions of minimum widths b 1 . [0024] Possibly provided at the first base of the male end segment are at least two lengthening segments that may be arranged in complementary recesses of the female end segment. These lengthening segments thus provide additional transversal undercut regions, which permits improved meshing of the female end segment with the male end segment. [0025] Lateral surfaces formed by the first foot segment of the male end segment are advantageously embodied at an acute angle to lateral transverse surfaces embodied in the first male transversal undercut region by first and second extension parts. [0026] The extension parts comprise lateral transverse surfaces for embodying the at least one outer transversal undercut region. The lateral transverse surfaces, with lateral longitudinal surfaces of the foot segment of the male end segment, form an acute angle W in a range from approximately 45° to approximately 88°, possibly in a range from approximately 68° to approximately 88°, possibly in a range from approximately 75° to approximately 86°. Possibly, the acute angle W is 80°+5°, which means that an acute angle W of 80° is possible, but it may have a production tolerance of +5°. [0027] The minimum widths b 21 and b 22 of both outer longitudinal segments and the minimum width b 3 of the second foot segment of the female end segment, when present, are selected such that they have a ratio b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ) of approximately 0.79 to approximately 1.27, possibly approximately 0.85 to approximately 1.18, more possibly approximately 0.95 to approximately 1.05 to the minimum width b 1 of the foot segment of the male end segment or to the minimum widths b 11 and b 12 of the longitudinal segments in the region of the recess. This ratio has proved to be essential during the calculation by means of finite element analysis for supplying the best figures for tensile stresses that occur. In principle the ratios of the minimum widths (cross-section width ratios) of the male and female end segments are formed systematically at a first male and a first female stage, or at a second male and second female stage, or at a third male and third female stage, etc., relative to such outer transversal undercut regions, and are possibly in the aforesaid regions in the context of the present disclosure. [0028] It is particularly possible that a width b 5 of the first base or of the lengthening segments that are provided on the first base of the male end segment is at least 1.0 mm, the width b 5 is possibly in a range from approximately 1.2 mm to approximately 2.0 mm, if lengthening segments are provided, wherein the width b 5 of the first base then possibly essentially equals the width of the lengthening segments. If no lengthening segments are provided, the width b 5 of the first base is possibly between approximately 1.5 mm and approximately 3.2 mm. [0029] In a finite element analysis, it was shown that the fastener has excellent values not only for static tensile elongation, but also for dynamic tensile-bending strain. In addition, finite element methods demonstrated that the inventive fastener yield very good values for a static crack opening, determined in an intermediate stress step during the assembly of the binder. For all of the aforesaid variables that are determined normalized using finite element methods, values less than 100%, and possibly less than 80%, could be determined. This means that only extremely small crack openings will occur in use or during post-production delivery of the closed, ring-shaped fastener. The values for dynamic tensile-bending strain are in particular <=100 possibly at a maximum of approximately 80%, possibly a maximum of approximately 75%, possibly in a range from approximately 20% to approximately 80%, and thus are values that are clearly below those values for puzzle connections according to the prior art, likewise determined by finite element methods and normalized, the values of which are often significantly greater than 100%. [0030] In one example, the second foot segment of the female end segment, when present, is embodied proceeding from the base thereof tapering to a minimum width b 3 . Furthermore, in this example a transition angle β between base and second foot segment is in a range from approximately 91° to approximately 110°, possibly in a range from approximately 93° to approximately 108°. Furthermore, arranged between lateral surfaces of the second foot segment and the lower lateral surfaces of the head part of the female end segment there can be radial regions having notch radii of at least approximately 0.3 mm, further possible are notch radii of at least approximately 0.5 mm, and yet further possible are notch radii in a range from approximately 0.3 mm to approximately 0.9 mm. It is possible that different notch radii are provided in the aforesaid radial ranges. Particularly possible in the range of minimum widths, such as for instance the minimum width of the second foot segment of the female end segment, are radii of approximately 0.7 mm to approximately 0.9 mm, possibly approximately 0.8 mm to approximately 0.9 mm, to which then a minimum radius in a range from approximately 0.3 mm to approximately 0.4 mm can connect. The aforesaid minimum radii, which are possibly in a range from approximately 0.25 mm to approximately 0.5 mm, possibly in a range from approximately 0.3 mm to approximately 0.4 mm, serve to make available the most possible functions such as undercuts or load-bearing cross-sectional surfaces of the inventive fastener on the available narrow space. A normal width b of a fastener is in a range from approximately 8 mm to approximately 20 mm, possibly approximately 9 mm to approximately 13 mm. However, these minimum radii are not used in the region of the minimum widths, because otherwise strong notch effects would occur there. Only when there is at least a 0.1 mm enlargement of the cross-section due to a larger radius, in particular a radius in a range from approximately 0.7 mm to approximately 0.9 mm, should a minimum radius be provided connecting thereto. In the region of a critical cross-section, that is, a minimum cut or width of the male or female end segment, for instance a minimum width of the foot segments, possibly the largest possible notch radii are used in a range from approximately 0.4 mm to approximately 1 mm, possibly to approximately 0.9 mm. The transition from a minimum radius to a larger radius or vice versa is always tangentially continuous. The aforesaid local radii of curvature are advantageously determined by comparing different known conforming radii. [0031] At least parts of, possibly all, the lateral surfaces of the head part of the female end segment, when present, are advantageously embodied curved with notch radii of at least approximately 0.3 mm, possibly of at least approximately 0.5 mm, more possibly with notch radii in a range from approximately 0.3 mm to approximately 0.9 mm. In this case, as well, different radii may connect to one another, as described in the foregoing. One lateral head surface of the head part is embodied in at least one sub-region approximately parallel to the base of the female end segment. It is particularly possible that the radial regions of the lateral surfaces of the head part transition, with notch radii of at least approximately 0.5 mm, possibly at least approximately 0.7 mm, particularly possibly in a range of approximately 0.7 mm to approximately 0.9 mm, into the lateral head surface of the head part. A linear region without any curvature may be provided following the radial region. [0032] In one example, an outer longitudinal segment whose outer wall transitions flush into the outer wall of the fastener is arranged on both sides of the foot segment of the female end segment. In their ends that are associated with the male end segment, the longitudinal segments may have recesses in which lengthening segments of the male end segment may be arranged. This provides additional longitudinal undercuts that further prevent the risk of a connection between male and female end segments in a closed inventive fastener from being opened if there is a bending stress. [0033] In a first embodiment, the two outer longitudinal segments project beyond the head part of the female end segment in a length direction of the fastener. In a second embodiment, as seen in a length direction of the fastener, the head part of the female end segment projects beyond the outer longitudinal segments, or projects out beyond the ends of the outer longitudinal segments. In the second embodiment, therefore, the male end segment has a recess embodied beyond the base thereof as seen in the length direction of the strip, in which recess the foot part engages with the head part of the complementary female end segment. [0034] In one example of the inventive fastener, in addition to the at least one outer transversal undercut region, the male end segment includes at least one inner undercut region. It may also be provided that at least two or three or even more transversal undercut regions are provided, but possibly one or two or three transversal undercut regions are provided. [0035] In another example, arranged on the end of the foot segment of the male end segment facing away from the base is a head part with extension parts that embody the inner undercut region, in particular in that they form a recess for foot part with head part of a female end segment. [0036] Lateral surfaces of the extension parts are advantageously approximately parallel to the outer wall of the fastener. However, it may also be provided that the lateral surfaces are slightly angled to the outer wall of the fastener, i.e., especially advantageously the head part of the male end segment as seen in the long direction of the fastener tapers somewhat. The deviations from a parallel orientation are possibly in a range from approximately +/−10°, more possibly in a range from approximately +/−5°. The lateral surfaces of the extension parts may be not only linear, which is preferred, but also in another manner, in particular they may have bent regions that form bulges or indentations in the extension parts of the head part of the male end segment. The transition between the lateral surfaces of the extension parts of the head part of the male end segment and the particular lateral head surfaces thereof, which may be associated with the base of the female end segment, is possibly at a right angle. For technical production reasons, however, minimum notch radii may be up to 0.3 mm. This cannot be avoided for technical production reasons. [0037] Furthermore, between the extension parts is a recess that is complementary to the foot segment with head part, when present, arranged on the base of the female end segment. The recess may be described as approximately mushroom head-shaped. Because of this, the center elements that are arranged in the male end segment and that comprise foot part and head part with the two extension parts and the recess, are shaped something like a stag beetle. When more than one inner undercut region is provided, tree-like contours may then be added, for instance. [0038] In another example, a length l of the foot segment and of the head part with the extension parts of the male end segment is shorter than a width b of the fastener. The length l is possibly approximately 70% to approximately 98%, more possibly approximately 78% to approximately 95%, of the width b of the fastener. [0039] The present disclosure further relates to the use of the fastener for fastening bellows on joint housings, in particular on outer joint housing parts and/or shafts, especially of automobiles, especially of constant velocity joints. From bellows and a fastener a system is formed that makes it possible to fasten bellows. In particular, this system has a pleated bellows and/or a roller bellows. SUMMARY OF THE DRAWINGS [0040] The foregoing and other advantages of the present fastener are explained in greater detail using the following figures. [0041] FIG. 1 is a top view onto a ribbon-like inventive fastener in a first example; [0042] FIG. 2A is a male end segment of the fastener according to FIG. 1 ; [0043] FIG. 2B is a female end segment of the fastener according to FIG. 1 ; [0044] FIG. 3 is a perspective elevation of the fastener according to FIGS. 1 through 3 in the closed ring condition. [0045] FIG. 4 is a top view onto a second example of a closed ring-shaped fastener; [0046] FIG. 5 is a third example of a closed fastener; [0047] FIG. 6 is a fourth example of a closed fastener; [0048] FIG. 7 is a fifth example of a closed fastener. [0049] FIG. 8 is a sixth example of a closed fastener; [0050] FIG. 9 is a seventh example of a closed fastener; [0051] FIG. 10 is an eighth example of a closed fastener; [0052] FIG. 11 is a ninth example of a closed fastener; and, [0053] FIG. 12 is a detail Y from FIG. 4 . DETAILED DESCRIPTION [0054] It should first be noted that the examples of the fastener depicted in the figures should not be interpreted as limiting; for instance, two or more foot segments with head part and extension parts may also be arranged at the base of the female and male end segments in the case of the male end segment. The features described in the figures may be combined to create another embodiment with the features provided in the description above. Moreover, it should be noted that the reference numbers indicated in the description of the figures do not limit the scope of protection for the present invention, but instead merely refer to the exemplary embodiments illustrated in the figures. Provided no information to the contrary is explicitly provided, identical parts or part with the same function have the same reference numbers in the following. [0055] FIG. 1 is a top view onto a first example of a fastener 10 , which is shown in a ribbon-like shape, i.e., in the non-closed condition. The fastener 10 has a male end segment 14 and a female end segment 12 between which a strip segment 12 is arranged. The fastener 10 has an outer wall 11 on both sides. [0056] FIG. 2A depicts a first embodiment of the male end segment 14 of the fastener 10 according to FIG. 1 . A width b, determined between the outer walls 11 , of the fastener 10 or strip segment 12 , is greater than a length l of the male end segment, measured between a base 22 and lateral head surfaces 33 . 1 and 33 . 2 . The length l is approximately 80% of the width b. [0057] The male end segment 14 has a foot segment 20 and a head part 21 . The head part 21 has two extension parts 32 . 1 and 32 . 2 that project laterally beyond an outer contour of the foot part 20 . The foot part 20 has lateral longitudinal surfaces 30 . 1 , 30 . 2 , an obtuse angle γ (gamma), approximately 93°, being formed between the base 22 and the lateral longitudinal surfaces 30 . 1 and 30 . 2 . A notch radius r 5 of approximately 0.3 mm is provided in the region of the transition from the base 22 to the lateral longitudinal surfaces 30 . 1 and 30 . 2 . The foot part 20 is embodied tapering to a minimum width b 1 . Provided following this minimum width b 1 is a first notch radius r 1 , having a value of 0.8 mm, which transitions continuously tangentially into a notch radius r 2 of 0.3 mm. These notch radii r 1 and r 2 represent the transition from the lateral longitudinal surfaces 30 . 1 and 30 . 2 of the foot segment 20 to lateral transverse surfaces 34 . 1 and 34 . 2 of the extension parts 32 . 1 and 32 . 2 , which lateral transverse surfaces 34 . 1 and 34 . 2 are arranged in a first and only outer undercut region 26 . These then transition into lateral surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 with a minimum notch radius r 3 of 0.3 mm and connecting thereto continuously tangentially with a notch radius r 4 of 0.8 mm. The lateral surfaces 35 . 1 and 35 . 2 are not embodied running parallel to the outer wall 11 of the fastener 10 , but instead at an angle of approximately 3° thereto, so that the extension parts 32 . 1 and 32 . 2 are embodied somewhat tapering toward the lateral head surfaces 33 . 1 and 33 . 2 thereof that can be associated with the female end segment 16 . This provides a region, following the notch radius r 4 , having a minimum width b 2 in the complementary female segment 16 , as may be seen below in FIG. 2 b . In the male end segment 14 , the foot segment 20 has a greater width b 4 on the base 22 than in the region of the minimum width b 1 . [0058] The transition between the lateral longitudinal surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 into the lateral head surfaces 33 . 1 and 33 . 2 runs essentially at a right angle. [0059] Due to production tolerances, however, notch radii may be up to 0.3 mm. [0060] The lateral transverse surfaces 34 . 1 and 34 . 2 of the extension parts 32 . 1 and 32 . 2 are embodied at an acute angle W of 85° with the lateral longitudinal surfaces 30 . 1 and 30 . 2 of the foot segment 20 . [0061] The head part 21 of the male end segment 16 has a mushroom head-shaped recess 38 that is for forming an inner undercut region 36 and that is embodied proceeding from the lateral head surfaces 33 . 1 and 33 . 2 of the extension parts 32 . 1 and 32 . 2 . The lateral head surfaces 33 . 1 and 33 . 2 transition to inner lateral longitudinal surfaces 40 . 1 and 40 . 2 for forming a sort of mushroom stem for the mushroom head-shaped recess 38 . The mushroom head of the mushroom head-shaped recess 38 has a lateral base surface 41 , some of which is linear and parallel to the base 22 and transitions into curved inner lateral surfaces 42 . 1 and 42 . 2 without any linear segments so that ultimately a mushroom head is formed. Minimum widths b 61 and b 62 of the extension parts 32 . 1 and 32 . 2 may be found in the region of the mushroom head-shaped recess 38 . [0062] FIG. 2 b depicts the female end segment 16 of the fastener 10 in which are shown the first and only outer transversal undercut region 27 , also cited with respect to the complementary embodiment to the male end segment 14 , and the innerly disposed transversal undercut region 36 . The first transversal undercut regions 26 and 27 extend from the minimum width b 1 of the foot segment 20 of the male end segment 14 to the minimum width b 21 or b 22 of longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 . The innerly disposed transversal undercut region 36 extends from a minimum width b 3 of a foot segment 56 of the female end segment 16 to the minimum widths b 61 and b 62 of the extension parts 32 . 1 and 32 . 2 of the male end segment 14 . Proceeding from a base 54 of the end segment 16 , a foot segment 56 with a head segment 57 is arranged approximately in the center. The foot segment 56 has a minimum width b 3 . Lateral longitudinal surfaces 58 . 1 and 58 . 2 of the length segment 56 transition from an obtuse angle β of approximately 95° into the base 54 . The foot segment 56 is thus embodied tapering towards the head part 57 . Connecting to the lateral longitudinal surfaces 58 . 1 and 58 . 2 of the length segment are lower lateral transverse surfaces 63 . 1 and 63 . 2 that are embodied at least in part parallel to the base 54 and transition to curved lateral surfaces 62 . 1 and 62 . 2 , which themselves transition to a lateral head surface 60 that is embodied with a center sub-region approximately parallel to the base 54 . In the transition between the lateral longitudinal surfaces 58 . 1 and 58 . 2 of the foot segment 56 and the lower lateral transverse surfaces 63 . 1 and 63 . 2 , radial regions 59 . 1 and 59 . 2 immediately following the minimum width b 3 have a notch radius of 0.8 mm and then tangentially continuously a notch radius of 0.3 mm. [0063] Length segments 50 . 1 and 50 . 2 , whose outer walls 51 . 1 and 51 . 2 transition flush into the outer wall 11 of the fastener 10 , are embodied on both sides of the mushroom head-shaped center formed by the foot segment 56 and the head part 57 . At its end that may be associated with the male end segment, the length segments 50 . 1 and 50 . 2 have recesses 53 . 1 and 53 . 2 in which extension segments 24 . 1 and 24 . 2 (see FIG. 2A ) of the male end segment 14 may engage. This provides a longitudinal undercut 28 (see FIG. 2A ). Projections 52 . 1 and 52 . 2 of the length segments 50 . 1 and 50 . 2 , associated with the male end segment 14 , come to be positioned therein in recesses 25 . 1 and 25 . 2 (see FIG. 2A ). [0064] The length segments 50 . 1 and 50 . 2 have minimum widths b 21 and b 22 . These minimum widths b 21 and b 22 follow second inner lateral transverse surfaces 65 . 1 and 65 . 2 within the undercut region 27 and are in the transition to the second inner lateral longitudinal surfaces 64 . 1 and 64 . 2 , wherein immediately connected to the minimum widths b 21 and b 22 is a notch radius of 0.8 mm and provided connected therein is a notch radius of 0.3 mm. The second inner lateral transverse surfaces 65 . 1 and 65 . 2 then transition into the first inner lateral transverse surfaces 66 . 1 and 66 . 2 . [0065] The ratio of the widths b 1 :(b 21 +b 22 +b 3 ) is approximately 0.87. With such a ratio, the minimum cross-sectional width of the male end segment 14 and the minimum cross-sectional widths of the female end segment 16 optimize the values for tensile stresses in the fastener once it has been closed to create a ring. [0066] The outer first undercut region 26 of the male end segment 14 comprises the lateral transverse surfaces 34 . 1 and 34 . 2 with connecting radial regions. According to FIG. 2B , the inner undercut region 36 is formed by the lower lateral transverse surfaces 63 . 1 and 63 . 2 and the radial regions connected thereto. [0067] FIG. 3 is a perspective elevation of the first example of the fastener 10 , shaped as a closed ring. In contrast, FIG. 4 is a top view onto a closed ring in a second example of the fastener 10 , the detail Y being shown in FIG. 6 . This second example is essentially similar to the first example according to FIGS. 1 through 3 , but the lateral longitudinal surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 of the head part 21 are oriented exactly parallel to an outer wall 11 of the fastener 10 . In addition, an angle α, which is determined by the lateral transverse surfaces 34 . 1 and 34 . 2 and their linear segments on the one hand and, on the other hand, by a straight line running through the base 22 of the male end segment 14 or a parallel thereto, is 10° and not 5°, as in the example according to FIG. 2A . Consequently, in this example the value for the acute angle W, which is not shown in FIG. 12 , is approximately 80°, since the angle γ, which is also not shown in FIG. 12 , is 93°, just as in the first example according to FIG. 2A . However, the acute angle W may also be, for instance, 70° in an alternative to the example according to FIG. 12 . FIG. 12 provides an idealized view of the union of the male end segment 14 and the female end segment 16 on the fastener 10 that has been closed to create a ring. In fact, due to the use of bending tools there may be minor material deformations, however, so that the precise geometrical values, that is, the precise shape of the male and female end segments 14 , 16 in the closed ring, deviate somewhat from those of the open ribbon segment as shown in FIGS. 1 and 2 a/b. [0068] FIG. 5 depicts a third example of the inventive fastener 10 that has three stages of outer transversal undercut regions, wherein FIG. 7 illustrates a similarly embodied fifth example. In the region of a first base 22 of a male end segment 14 , the third example is similar to the male end segment 16 according to FIG. 2 a . A base 22 of the fifth example according to FIG. 7 is different from that of the third example in that there a material accumulation 74 . 1 and 74 . 2 is provided to a first male foot segment 20 . 1 , which material accumulation is more or less linearly increasing proceeding from the base 22 so that chamfering is formed. In the region of a first base 22 of a male end segment 14 , the third example is similar to the male end segment 16 according to FIG. 2A . The third example has in particular a first transversal undercut region 26 . 1 , a second transversal undercut region, 26 . 2 , and a third transversal undercut region 26 . 3 of the male end segment 14 , as well as a first transversal undercut region 27 . 1 , a second transversal undercut region 27 . 2 , and a third transversal undercut region 27 . 3 of the female end segment 16 . The third example, depicted in FIG. 5 , may be considered as (fir) tree-like. The cross-sectional width ratio of the first stage is calculated from the minimum width b 1 of the first male foot segment 20 . 1 and the minimum widths b 11 and b 12 of the extension segments 50 . 1 and 50 . 2 of the female end segment 16 (see also FIG. 7 ). It is approximately 1, and is likewise for the fifth embodiment according to FIG. 7 . The cross-sectional width ratio of the third stage, with respect to the third outer transversal undercut of the male end segment 14 and of the female end segment 16 , is calculated from the width b 2 of a third male foot segment 20 . 3 of the male end segment 14 and minimum widths b 21 and b 22 of the retention parts 50 . 1 and 50 . 2 of the female end segment 16 (b 2 :(b 21 +b 22 )). It is approximately 0.93, and is likewise for the fifth example according to FIG. 7 . [0069] FIG. 6 depicts a fourth example of an inventive fastener 10 that is the same as the sixth example according to FIG. 8 (see below, as well) apart from an inner undercut region 36 . This fourth example has a two-stage embodiment with transversal outer undercut regions 26 . 1 and 26 . 2 or 27 . 1 and 27 . 2 . A first transversal undercut region 26 . 1 of a male end segment 14 and a second transversal undercut region 27 . 2 of the female end segment 16 are provided, as is a first transversal undercut region 27 . 1 of a female end segment 16 and a second transversal undercut region 27 . 2 of the female end segment 16 . A cross-sectional width ratio on the second stage, calculated from a minimum width b 2 of a second male foot segment 20 . 2 and widths b 21 and b 22 from longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 in the region of the second transversal undercut 27 . 1 is approximately 1. A trough-like recess 48 is arranged in the male end segment 16 in the second head part. [0070] FIG. 8 depicts a sixth example of the inventive fastener 10 in the closed ring-shaped condition. In this example, two outer transversal undercut regions 26 . 1 and 26 . 2 of a male end segment and two outer transversal undercut regions 27 . 1 and 27 . 2 of the female end segment 16 are provided. The shape of the male end segment may be considered to be tree-like. The minimum width b 2 of a second male foot segment 20 . 2 in the second undercut region 26 . 2 is therefore used to determine for the ratio of the second stage b 2 :(b 21 +b 22 ), which is approximately 0.8, while for determining the cross-sectional width ratio on the first stage, a minimum width b 1 of a first male foot segment 20 . 1 in the first undercut region 26 . 1 is used and widths b 11 and b 12 of the outer lateral longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 in the undercut region 27 . 1 are used, as well as a minimum width b 3 of the inner undercut region 36 , and the ratio there b 1 :(b 11 +b 12 +b 3 ) is approximately 0.8. Because two outer undercut regions 26 . 1 and 26 . 2 are provided, the sixth example according to FIG. 8 has excellent values for static tensile elongation. Following the first undercut region 26 . 1 , then, a longitudinal undercut region is again provided due to the trough-like formation 44 , as is provided by the projections 24 . 1 and 24 . 2 in the first example according to FIG. 2 a , for instance. In addition, however, corresponding projections 24 . 1 and 24 . 2 are also provided on the base 22 . Otherwise the upper part with the recess 38 is identical to the second example according to FIGS. 4 and 12 . If there was a desire to provide two inner undercut regions, in a tree-like manner a recess 38 would be provided in the adjacent segment or a foot 20 . 1 would also be provided. [0071] FIG. 9 depicts a seventh example of the inventive fastener 10 that has first transversal undercut regions 26 . 1 and second transversal undercut regions 26 . 2 of the male end segment 14 and first transversal undercut regions 27 . 1 and second transversal undercut regions 27 . 2 of the female end segment 16 . On the second stage the cross-sectional width ratio, determined from a minimum width b 2 of a second male foot segment 20 . 1 and minimum widths b 21 and b 22 of longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 , is approximately 1, for the first stage the cross-sectional width ratio is approximately 0.91. The seventh example according to FIG. 9 has additional trough-like recesses 44 following the extension parts 32 . 1 and 32 . 2 and facing the second male foot segment 20 . 2 , though which is provided additional longitudinal undercuts and further improved meshing of the female end segment 16 with the male end segment 14 . The second head region of the male end segment 14 has a depression 82 , and at the base of this segment are arranged lengthening segments 80 . 1 and 80 . 2 in the form of small projections having a primarily curved outer contour that has a width b 5 of approximately 1.5 mm. These further improve meshing and make additional undercuts available. [0072] FIG. 10 depicts an eighth example of a fastener 10 similar to that shown in FIG. 9 . In particular the cross-sectional width ratios of the eighth example correspond to those of the seventh example according to FIG. 9 . However, the eighth example is different in the region of the first base 22 of the male end segment 14 . Similar to the first example according to FIG. 2A , provided in the male end segment 14 are lengthening segments 24 . 1 and 24 . 2 into which projections 52 . 1 and 52 . 2 of the longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 engage. [0073] FIG. 11 depicts a ninth example of the fastener 10 when closed, i.e., with male and female end segments, this example differing from, e.g., the first and second embodiments primarily in that the foot segment 56 of the female end segment 16 has been lengthened significantly, specifically beyond the base 22 of the male end segment 14 in the length direction of the fastener 10 . Because of this, the head part 57 is disposed on the far side of the base 22 so that then, ultimately, embodied in the male end segment 14 is a recess 38 that is displaced beyond the base 22 in the length direction of the fastener. In the embodiment according to FIG. 11 , the minimum width b 1 is formed by the two sub-widths b 11 and b 12 , so that there is a ratio (b 11 +b 12 ):(b 21 +b 22 +b 3 ) of 0.8. The widths b 11 and b 12 of the male end segment 16 then relate to the longitudinal segments 18 . 1 and 18 . 2 thereof, which were created due to the displacement of the recess 38 beyond the first base 22 in the length direction of the fastener. [0074] With the disclosed fastener, a fastener is provided that supplies better values in terms of tensile and bending load, so that ultimately crack openings are prevented during operation and the service life of the inventive fastener is thereby significantly extended.

A fastener, in particular for bellows, comprises a male end segment and a female end segment complementary to the male end segment. The fastener can be used to fasten bellows to joint housings and/or shafts, said fastener having improved closing behavior.

RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 11/298,944 filed Dec. 12, 2005, which is incorporated herein by reference. BACKGROUND A. Field of the Invention Implementations consistent with the principles of the invention relate generally to information dissemination and, more particularly, to decentralized techniques for allowing web annotation. B. Description of Related Art The World Wide Web (“web”) contains a vast amount of information. When browsing a particular document on the web, such as a web page, users are typically limited to only viewing the web page itself. Supplementary information, such as information provided by other web sites or other web users about the particular site being viewed, can be difficult to easily view. For example, assume that a user is viewing the manufacturer's web page relating to a product the user is interested in purchasing. To see other web pages reviewing or commenting on the product, the user may need to separately search for other web sites pages that contain formal reviews or other comments about the product. One attempt to allow users to annotate particular web pages with comments that could be viewed by other users when visiting the web page was the “Third Voice” browser plug-in. Third Voice allowed users to post public notes about a web site that could then be seen by other Third Voices users that later visit the web site. One problem suffered by this product was that comments about a web site were often “low quality” comments that were spammy and/or inappropriate. SUMMARY One aspect is directed to a method that includes detecting when a user visits a web site; receiving, in response to the detection, a group of blog posts that link to the web site; and displaying an indication of the group of blog posts to the user while the user is visiting the web site. Another aspect is directed to a method including detecting when a user visits a web site and submitting, in response to the detection, a search query to a search engine. The search query requests documents relevant to the web site. The method further includes receiving documents in response to the submitted search query and displaying an indication of the documents to the user while the user is visiting the web site. Yet another aspect is directed to a system including a blog search engine and a client device connected to the blog search engine over a network. The client device includes a software component configured to display web sites to users and to concurrently determine and display portions of blog posts that link to a currently displayed web site. The blog posts are determined based on a query to the blog search engine for blog posts linking to the currently displayed web site. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, explain the invention. In the drawings, FIG. 1 is a diagram of an exemplary system in which concepts consistent with the principles of the invention may be implemented; FIG. 2 is a diagram of an exemplary client or server shown in FIG. 1 ; FIGS. 3A and 3B are diagrams of exemplary graphical user interfaces presented to a user by the DCom (“Distributed Web Comments”) component and browser shown in FIG. 1 ; FIG. 4 is a flowchart illustrating exemplary operations through which a user may initially install or configure the DCom component; FIG. 5 is a flow chart illustrating exemplary operations that may be performed during minimized operation of the DCom component; FIG. 6 is a flow chart illustrating exemplary operations that may be performed during operation of the DCom component; and FIGS. 7A-7D are diagrams of additional exemplary graphical user interfaces that may be presented to a user by the DCom component and the browser. DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings. The detailed description does not limit the invention. Overview As described herein, an easy entry point is provided through which users may annotate web pages and see other users' annotations. The annotations may be taken from blog posts relating to the web page being annotated. A “blog,” which is a shortened term for weblog, may be defined as a website through which an individual or a group generates text, photographs, video, audio files, and/or links, typically but not always on a daily or otherwise regular basis. Authoring a blog, maintaining a blog or adding an article to an existing blog is called “blogging”. Individual articles on a blog are called “blog posts”, “posts”, or “entries”. The person who posts these entries is called a “blogger”. Frequently, bloggers generate posts that comment on and/or link to other web pages. Consistent with an aspect of the invention, a user viewing a web site may concurrently view blog posts about the web site. By using blog posts as annotation information for a web site, inappropriate or spammy comments about a web site can be reduced, as blog posts tend to have an inherent level of seriousness associated with them and the blog posts can be ranked or otherwise filtered based on the quality of the underlying blog. System Description FIG. 1 is an exemplary diagram of a system 100 in which concepts consistent with the principles of the invention may be implemented. System 100 may include clients 110 coupled to servers 120 and 122 via a network 140 . Network 140 may include a local area network (LAN), a wide area network (WAN), a telephone network, such as the Public Switched Telephone Network (PSTN), an intranet, the Internet, or a combination of networks. Two clients 110 and two servers 120 and 122 have been illustrated as connected to network 140 for simplicity. In practice, there may be more clients and/or servers. Also, in some instances, a client may perform the functions of a server and a server may perform the functions of a client. Clients 110 may include a device, such as a wireless telephone, a personal computer, a personal digital assistant (PDA), a lap top, or another type of computation or communication device, a thread or process running on one of these devices, and/or an object executable by one of these devices. Clients 110 may include software such as a browser 115 that is used to access and display web pages from a web server such as server 120 or 122 . Browser 115 may include, for example, the Firefox™ browser. Clients 110 may additionally include a software component designed to interact with browser 115 to allow users to annotate and view annotations relating to web pages. This software component will be referred to herein as DCom (Distributed Web Comments) component 118 . DCom component 118 may be, for example, in some implementations, a web browser plugin or extension. In other implementations, DCom component 118 may be a separate program on client 110 . Servers 120 and 122 may provide services on behalf of clients 110 , and may include, for example, a web server, a file server, or an application server. In one implementation, server 120 may include a search engine 125 usable by clients 110 . Search engine 125 may be a query-based document search engine. Search engine 125 may be designed to return links to web pages that include information relevant to a search query. Search engine 125 may be a specialized search engine, such as a blog search engine designed to return blog posts or links that are relevant to user's search query. Search engine 125 may respond to user search queries based on documents stored in database 135 . The documents stored in database 135 may include web pages that are connected to network 140 and that were previously crawled and indexed by search engine 125 . When search engine 125 is a blog search engine, the documents stored in database 135 may be indexed blog posts or blogs. Although shown as a single database in FIG. 1 , database 135 could be distributed over multiple storage devices. Similarly, although shown as a single device in FIG. 1 , servers 120 / 122 and search engine 125 may be implemented in a distributed manner over multiple computing devices. FIG. 2 is an exemplary diagram of a client 110 , server 120 , or server 122 , referred to as computing device 200 , according to an implementation consistent with the principles of the invention. Computing device 200 may include a bus 210 , a processor 220 , a main memory 230 , a read only memory (ROM) 240 , a storage device 250 , an input device 260 , an output device 270 , and a communication interface 280 . Bus 210 may include a path that permits communication among the components of computing device 200 . Processor 220 may include any type of processor, microprocessor, or processing logic that may interpret and execute instructions. Main memory 230 may include a random access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processor 220 . ROM 240 may include a ROM device or another type of static storage device that stores static information and instructions for use by processor 220 . Storage device 250 may include a magnetic and/or optical recording medium and its corresponding drive. Input device 260 may include a mechanism that permits a user to input information to computing device 200 , such as a keyboard, a mouse, a pen, voice recognition and/or biometric mechanisms, etc. Output device 270 may include a mechanism that outputs information to the user, including a display, a printer, a speaker, etc. Communication interface 280 may include any transceiver-like mechanism that enables computing device 200 to communicate with other devices and/or systems. For example, communication interface 280 may include mechanisms for communicating with another device or system via a network, such as network 140 . Software components of system 100 , such as search engine 125 , browser 115 , and DCom component 118 may be stored in a computer-readable medium, such as memory 230 . A computer-readable medium may be defined as one or more physical or logical memory devices and/or carrier waves. The software instructions defining the software components may be read into memory 230 from another computer-readable medium, such as data storage device 250 , or from another device via communication interface 280 . The software instructions contained in memory 230 cause processor 220 to perform processes that will be described later. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes consistent with the present invention. Thus, implementations consistent with the principles of the invention are not limited to any specific combination of hardware circuitry and software. Operation of DCom Component 118 FIG. 3A is a diagram illustrating an exemplary graphical user interface 300 for a web browser 115 presented to a client 110 using DCom component 118 . User interface 300 may include menu section 305 , navigation toolbar 310 , a web page display section 315 , and a status bar 320 . Menu section 305 presents a number of menus to the user through which the user may control the operation of web browser 115 . Navigation toolbar 310 may include one or more controls through which the user can control web browser 115 when navigating the web, such as “forward” and “back” buttons and an input box to enter uniform resource locators (URLs). Web page display section 315 may present the web page currently being visited and status bar 320 may display status information relating to the operation of web browser 115 . Status bar 320 may additionally display an indication of how highly the web site or web page currently being visited (i.e., the site in display section 315 ) is annotated. In the example shown in FIG. 3A , this function is performed via a “buzz” icon 325 , which is illustrated as a graphical meter. Buzz icon 325 may be displayed in status bar 320 on behalf of or under the control of DCom component 118 . Buzz icon 325 may change based on a “buzz rating” determined based on the annotations associated with the current web site. For example, when a user is visiting a web site with no associated annotations, buzz icon 325 may not be shown or may be shown as an graphical bar or meter with an empty or zero reading. When a user is visiting a web site with annotations, buzz icon 325 may change to reflect the number, quality, and/or temporal relevance of the annotations. For example, a user visiting a site with a lot of annotations may see a buzz icon with a full meter reading. In some implementations, the size or color of buzz icon 325 may also change. The particular design used by buzz icon 325 to reflect the annotations for a site is not critical. In general, buzz icon 325 may be designed so that sites with a high “buzz” rating are given a “stronger” icon, where the buzz rating may be based on some combination of the number, quality, or timeliness of the annotations associated with the web site. In some implementations, timeliness of the annotations for a site may be based on timeliness relative to the last time the user visited a site. In other words, buzz icon 325 may indicate how much the annotations for the site have changed since the last time the user visited the site. Additionally, in some implementations, the functionality of buzz icon 325 may be presented to the user in sections of browser 115 other than status bar 320 . FIG. 3B is a diagram illustrating a second exemplary graphical user interface 350 for a web browser 115 presented to a client 110 using DCom component 118 . Graphical user interface 350 is similar to graphical user interface 300 , except that a sidebar 355 is additionally shown within web page display section 315 . Sidebar 355 may be displayed in response to the user indicating an interest in the annotations for a site. For example, the user may be able to toggle sidebar 355 by clicking on buzz icon 325 , by typing a specific keyboard combination, or by selecting the sidebar from menu 305 . Sidebar 355 may display the annotations, portions of the annotations, or links to the annotations associated with a particular site. Sidebar 355 may additionally allow the user to post comments to his/her blog about the site. As shown in the example of FIG. 3B , sidebar 355 displays portions of three blog posts, labeled as posts 360 - 362 , that link to the current web site. Each blog post 360 - 362 may include a link (i.e., the underlined portion), that, when selected by the user, may take the user to the web page corresponding to the selected blog post. Sidebar 355 may additionally include a “more” link 365 that, when selected, causes additional annotations to be shown, and a “create post” link 367 that, when selected, may provide a convenient entry point through which the user may create a blog post in their own blog about the web site. The operation of DCom component 118 in conjunction with browser 115 will next be described in more detail with reference to the flow charts shown in FIGS. 4-6 . FIG. 4 is a flowchart illustrating exemplary operations through which a user may initially install or configure DCom component 118 . The user may initially install DCom component 118 at client computer 110 at which DCom component 118 is to be used (act 401 ). DCom component 118 may be a browser plugin, extension, or other browser addon component that is downloaded from server 120 or 122 . In other implementations, DCom component 118 may be script or other code that can be downloaded and run by client 110 on an as-needed basis. In still other implementations, DCom component 118 may be a separate application that runs in parallel with browser 115 at client 110 . When initially running DCom component 118 , the user may be queried to determine whether they have a blog hosted at a site recognized by DCom component 118 (act 402 ). If yes, the user may enter their registration information, such as their username and password, for their blog (act 403 ). This information may be later used to allow the user to post or to begin a post from within sidebar 355 . If the user does not have a blog hosted at a site recognized by DCom component 118 , the user may be prompted to determine whether they would like to sign up for a new blog (act 404 ). If the user decides they would like to sign up for a new blog, a new web page may be opened at a registration page for the new blog. After the initial installation, login, and/or registration shown in acts 401 - 404 , DCom component 118 may execute normally on client 110 (act 405 ). Normal execution of DCom component 118 will be described in more detail below with reference to FIGS. 5 and 6 . After initial installation and registration, acts 401 - 403 may not need to be performed each time the user uses client 110 . FIG. 5 is a flow chart illustration exemplary operations that may be performed during minimized operation of DCom component 118 . DCom component 118 may monitor the browsing session of the user for changes to the web site or web page the user is viewing (act 501 ). When DCom component 118 detects a new site, or possibly, a new web page within a site, DCom component 118 may obtain the buzz rating, or information that can be used to obtain the buzz rating, for the site (acts 502 and 503 ). The buzz rating is designed to generally reflect the likelihood that a user will want to view the annotations for the site. As previously mentioned, the buzz rating may be based on some combination of the number, quality, or timeliness of the annotations associated with the web site. In one implementation, DCom component 118 may calculate the buzz rating based on the examination of the annotations (i.e., blog posts) that correspond to a site. The annotations may be obtained by querying a blog search engine, such as search engine 125 , in a manner that restricts the search results to blog posts that link to the current site. For example, queries to the existing Google™ blog search engine of the form “link: <URL>” restricts results to blog posts that link to “URL.” Using the example web site shown in FIG. 3A , DCom component may submit the query “link: labs.google.com”. The results of this query from search engine 125 may include a number of blog posts for this web site “labs.google.com”. Based on the number, timeliness, and/or quality of these blog posts, DCom component 118 may generate the buzz rating. As one example of generating a buzz rating, the buzz rating may be equal to the number of blog posts returned from search engine 125 that is more recent than a particular cut-off date (such as the date associated with the last time the user visited the site). The buzz rating calculated in act 503 may be presented to the user (act 504 ). For example, the buzz rating may be visually presented to the user via buzz icon 325 . As previously mentioned, buzz icon 325 may be designed so that sites with a high “buzz” rating are given a “stronger” (visually more distinctive) icon. FIG. 6 is a flow chart illustrating exemplary operations that may be performed during operation of DCom component 118 when the user is viewing the main user interface for DCom component 118 (e.g., when the user has clicked buzz icon 325 to display sidebar 355 ). DCom component 118 may retrieve the annotations, or links to the annotations, for the current site, such as by querying search engine 125 (act 601 ). The annotations may previously have been downloaded by DCom component 118 in generating the buzz rating ( FIG. 5 ). In this situation, DCom component 118 may not need to re-query search engine 125 . The annotations, or a pre-selected number of the annotations, may then be displayed to the user (act 602 ). In the example shown in FIG. 3B , three annotations for the current site are shown to the user in sidebar 355 . DCom component 118 may appropriately respond to user actions in sidebar 355 . For example, if the user clicks on a link associated with one of the annotations, browser 115 may be directed to display the complete blog or blog post corresponding to the annotation (act 603 ). In situations where more annotations are available, the user may choose to see more annotations in sidebar 355 , such as by selecting the “more” link 355 (act 604 ). Still further, the user may choose to post a comment about the current site by creating a post for their blog (act 605 ). The user may initiate their blog post by selecting “create post” link 367 . Doing so may, for example, take the user to a web page at which the user may manage the blog and, in particular, create a new post for the blog. The new blog post may be preset to include a link back to the current site (i.e., “labs.google.com” in the example shown in FIG. 3B ). Exemplary Additional User Interfaces As mentioned, the user interface shown in FIGS. 3A and 3B are exemplary. Additional exemplary user interfaces that may be provided by DCom component 118 will now be described with reference to FIGS. 7A-7D . In this exemplary implementation of DCom component 118 , DCom component 118 may communicate with the user through popup windows instead of through the sidebar shown in FIG. 3B . In some implementations, how DCom component 118 communicates with the user, such as a popup window or browser sidebar windows, may be a user-configurable parameter. FIG. 7A is a diagram illustrating an exemplary graphical user interface 700 for a web browser 115 presented to a client 110 using DCom component 118 . Graphical user interface 700 may include a buzz icon 725 that functions similarly to buzz icon 325 . Instead of sidebar 355 , graphical user interface 700 may include a popup window 755 that displays a number of annotations for the site currently being viewed. Popup window 755 may include a header link 760 for each annotation, a “show lots more” link 765 , and an “add comment” link 767 . Header link 760 , when selected by the user, may open a web browsing window at the blog post corresponding to the header. Show lots more link 765 and add comment link 767 may function similarly to “more” link 365 and “create post” link 367 , respectively. Specifically, show lots more link 765 , when selected, causes additional annotations for the web site, if available, to be displayed in popup window 755 . Add comment link 767 may provide a convenient entry point through which the user may create a blog post in their own blog about the web site. FIG. 7B is a diagram illustrating an exemplary graphical user interface 702 in which popup window 755 is shown as a smaller popup window. Users may switch between the larger version of popup window 755 and the smaller version of popup window 755 using standard sizing icons in the upper right corner of the window. FIG. 7C is a diagram illustrating an exemplary popup dialog 704 that may be provided to the user when the user selects “add comment” 767 link without having a registered blog. As shown, dialog 704 provides fields through which users may enter their blog username and password. Additionally, dialog 704 provides a link through which the user may register for a new blog and a link through which the user may recover a forgotten password. FIG. 7D is a diagram illustrating an exemplary dialog 706 that may be provided to the user when the user selects “add comment” link 767 and the user has registered their blog. As shown, dialog 706 provides an area 770 in which the user may compose their blog post. Area 770 may be pre-populated with a link back to the web page currently being viewed. In the example shown in FIG. 7D , this link is illustrated as the underlined text “Read . . . ”. When the user is ready to publish the blog post to his/her blog, the user may select “publish” button 772 . Although DCom component 118 was generally described above as receiving and operating on web annotations from a blog search engine, DCom component 118 may more generally operate to receive annotations from other search engines in which the search results are in someway limited by the site or web page currently being visited. More generally, DCom component 118 may operate to receive annotation information from any other website that links to and in someway comments on the current web site. The linking websites may include websites that in someway provide reviews, commentary, critiques, or feedback to the current website or webpage. Additionally, instead of receiving annotations from a search engine, DCom component 118 may receive the annotations from a different server, such as an annotation server designed to operate specifically with DCom component 118 . CONCLUSION Techniques for providing decentralized user web annotations were described above. The web annotations may be based on blog posts, providing the system with an existing initial base of web annotations. Additionally, because the annotations may be received from a blog search engine, which may already provide quality and/or spam filtering controls on the blogs it is indexing, the annotations are likely to be less spammy or inappropriate relative to existing web annotation systems. The foregoing description of exemplary embodiments of the invention provides illustration and description, but are not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while a series of acts have been described with regard to FIGS. 4-6 , the order of the acts may be varied in other implementations consistent with the invention. Moreover, non-dependent acts may be implemented in parallel. It will also be apparent to one of ordinary skill in the art that aspects of the invention, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement aspects consistent with the principles of the invention is not limiting of the invention. Thus, the operation and behavior of the aspects of the invention were described without reference to the specific software code—it being understood that one of ordinary skill in the art would be able to design software and control hardware to implement the aspects based on the description herein. Further, certain portions of the invention may be implemented as “logic” or as a “component” that performs one or more functions. This logic or component may include hardware, such as an application specific integrated circuit or a field programmable gate array, software, or a combination of hardware and software. No element, act, or instruction used in the description of the invention should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Annotations relating to web sites may be based on blog posts relating to the web sites. A user viewing a web site may concurrently view related blog posts about the web site. More particularly, in one implementation, a method includes detecting when a user visits a web page and receiving, in response to the detection, a group of blog posts that link to the web page. The method further includes displaying an indication of the group of blog posts to the user while the user is visiting the web site.

CLAIM OF PRIORITY [0001] This application is a continuation of and claims the benefit of priority under 35 U.S.C. §120 to Jeffrey W. Dlott et al., U.S. patent application Ser. No. 09/705,373, entitled “METHOD AND SYSTEM AUTOMATICALLY TO CERTIFY AN AGRICULTURAL PRODUCT,” filed on Nov. 2, 2000, which is hereby incorporated by reference herein in its entirety. FIELD OF THE INVENTION [0002] The present invention relates to information systems (IS) technology and information appliances for, inter alia, agricultural certification compliance, agricultural regulatory compliance, agricultural process management, and agricultural product marketing. More particularly, the present invention relates to capturing and providing data about agricultural products, practices and conditions with high integrity and credibility to consumers, regulatory agencies and certification authorities, agricultural process managers and agricultural product developers, processors and handlers. BACKGROUND OF THE INVENTION [0003] Consumers and purchasers of food and other agricultural products are becoming increasingly concerned about the exact natures of the foods that they are eating and the effect of agricultural practices on the environment. The public is directing the government to establish and enforce increasingly stringent regulations on the practices of farmers, ranchers, and food processors. Independent certification organizations with progressive agendas for environmental stewardship are gaining significant momentum and influence in the marketplace. The predominance of agriculture as the primary cause of surface water pollution in the United States is fueling the concerns of the voting public and consumers in general about the good environmental stewardship aspects and obligations of agricultural operations. The contribution of pollution to rivers, lakes and estuaries by agricultural operations, via the generation and/or introduction into the environment of pesticides, nutrients, siltation, pathogens and organic enrichment, is becoming more evident in the public and commercial discourse. [0004] The work of M. Tetrault and D. Grandbois, as disclosed in U.S. Pat. No. 5,885,461, issued 23 Mar. 1997, “Process and system for treatment of pig and swine manure for environmental enhancement”, is an example of inventive efforts to reduce the environmental impact of agricultural operations. Tetrault and Grandbois developed a protocol to remove water and sludge from animal waste of such a composition that the water and the sludge may be safely returned to the external environment and thus reduce pollution of animal manure, both liquid and solid, as generated by domestic animal farms. The efforts disclosed by Tetrault and Grandbois are biological and chemical in concept and in application and do not employ the value of information technology to the challenges of reducing pollution generation on farms. [0005] R. Hargrove and C. Zind, in U.S. Pat. No. 5,897,619, issued Apr. 27, 1999, “Farm management system”, present a technique of using an interactive information technology to, quoting here from the Abstract, “acquire, portray, and process field related data to thereby set rates on a field by field basis, verify that each policy complies with company, state, and federal regulations, verify that the configuration of each field allows the field to be insurable, and provide a method to validate claims of crop damage caused by weather.” [0006] Looking in developments outside the scope of agricultural practices, U.S. Pat. No. 5,999,909, issued 7 Dec. 1999, “Methods for establishing certifiable informed consent for a procedure”, A. Rakshit and W. Judd, reports in the Abstract that, “a method for establishing certifiable patient informed consent for a medical procedure, where, in one embodiment, the patient interacts with a video training system until mastery of all required information is successfully achieved. Training techniques which permit elicitation of measurable behaviors from a patient as a guide to discerning the level of knowledge of the patient are utilized. Certification is only granted when the measurable behavior approximately coincide with the legal and medical standards for establishing informed consent.” Rakshit and Judd thereby use an information technology system to correlate a statistical probability of subjective understanding of a respondent in a particular instant with the behavior of this sole respondent and upon the bases of earlier comprehensive studies of the association of numerous respondents' behaviors with their contemporaneous levels of understanding. [0007] Conventional approaches have attempted to thoughtfully empower agricultural process managers with tools and techniques efficiently and effectively to address the concerns of consumers, certifying bodies and governmental agencies. The existing suites of environmental certification standards (e.g., Federal and State organic food laws and non-governmental eco-label certification programs) neither require nor prescribe real-time certified monitoring of agricultural production practices. There presently exists a mismatch between the methods and tools of prior art data collection, as well as conventional automated analysis systems, and the informational needs and demands of the agricultural process manager, public and regulatory and certifying agencies, agricultural product processing, transportation and distribution agents, and consumers. In addition, there is a rapidly increasing concern on the part of the public and dedicated environmental organizations about the over use of pesticides and any resulting degradation of the environment by agricultural operations. [0008] Much of the raw data required by an agricultural manager to make critical decisions is obtained in the field. In particular, agricultural managers spend significant portions of their budgets on pesticide acquisition and application. Decisions made in pesticide use are largely based upon field data describing pest population detection and counts, and this data is managed outside of any formal reporting and documenting structure. [0009] The external pressures upon agricultural managers to justify pesticide use and to document the integrity of their pesticide decision-making is rapidly growing. Most agricultural managers are as concerned about the environment as other citizens, and actively seek to improve the quality of their decision-making and to demonstrate their sincerity to the public. SUMMARY OF THE INVENTION [0010] According to the present invention, there is provided a method of automatically certifying an agricultural product. Agricultural product data relating to an agricultural product is received at a management information system. The agricultural product data is automatically compared against compliance requirements stored by the management information system. A compliance result is automatically generated based on the automatic comparison of the agricultural product data against the compliance requirements. [0011] Other features of the present invention will be apparent from the accompanying drawings and from the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWINGS [0012] The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: [0013] FIG. 1 is a diagrammatic representation of an exemplary agricultural system within which the present invention may be deployed. [0014] FIG. 2 is a diagrammatic illustration of how seasonal production systems can be managed as long-term production systems, and seasonal production systems may deliver seasonal production impacts and long-term productions impacts. [0015] FIG. 3 is a flow chart providing an overview of a method, according to the present invention, of capturing, managing, processing and outputting data pertaining an agricultural product. [0016] FIG. 4 is a diagrammatic representation of the capture of data at multiple units that together constitute a chain of custody, according to an exemplary embodiment of the present invention. [0017] FIG. 5 is a diagrammatic representation of a data record, according to an exemplary embodiment of the present invention, that may be generated by a data capture device at each of the units of a chain of custody and thereafter communicated to the agricultural information system. [0018] FIG. 6 is a block diagram illustrating a compliance and chain of custody system, according to an exemplary embodiment of the present, that includes a chain of custody constituted by a collection of custodians, each of which provides input to the agricultural management information system. [0019] FIG. 7 is a diagrammatic representation illustrating a plurality of data capture devices, connected via a network to each other and to an agricultural management information system, according to an exemplary embodiment of the present invention. [0020] FIGS. 8A-8D are diagrams illustrating details regarding the operation of an exemplary hand-held device that includes a barcode reader. [0021] FIG. 8E illustrates an exemplary chart on which may be printed a collection of barcodes, each of which represents product data that may be ready by a barcode reader. [0022] FIG. 9 is a block diagram illustrating the hardware components of a hand-held device, according to an exemplary embodiment of the present invention. [0023] FIG. 10 is a block diagram illustrating system components implemented, for example, in software within a hand-held device. [0024] FIG. 11 is a flow chart illustrating a method, according to an exemplary embodiment of the present invention, of capturing data pertaining to an agricultural product. [0025] FIG. 12 is a block diagram illustrating an exemplary collection of data records that may be maintained within a database in an agricultural management information system. [0026] FIG. 13 is a block diagram illustrating further architectural details of an agricultural management information system, according to an exemplary embodiment of the present invention. [0027] FIG. 14 is a flow chart illustrating a method, according to an exemplary embodiment of the present invention, of automatically generating a compliance result based on the automated comparison of agricultural product data against compliance requirements in the form of certification requirements. [0028] FIG. 15 is a flow chart illustrating a method, according to an exemplary embodiment of the present invention, of communicating agricultural product information to a user. [0029] FIG. 16A illustrates the communication of a user interface by an agricultural management information system, via a network, to a computer system for display. [0030] FIG. 16B illustrates exemplary labels, each bearing a respective barcode, as applied to an assortment of agricultural products. [0031] FIG. 17A illustrates exemplary seasonal reports and historic reports of a number of leafhoppers identified within a particular trap both seasonally and over a number of years, the reports being generated by the agricultural management information system. [0032] FIG. 17B illustrates an example of a weekly pest management monitoring report, as generated by the agricultural management information system. [0033] FIG. 17C illustrates an exemplary aggregate report that graphically illustrates water use efficiency per year measured in acre/feet for a group of wine grape growers, the aggregate report being generated by the agricultural management information system. [0034] FIG. 17D illustrates an exemplary pesticide use report, as generated by the agricultural management information system. DETAILED DESCRIPTION [0035] A method and system automatically to certify an agricultural product are described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be evident, however, to one skilled in the art that the present invention may be practiced without these specific details. Agricultural System—Overview and Terminology [0036] FIG. 1 illustrates an exemplary agricultural system 10 that includes an agricultural production system 15 and agricultural production outputs 16 . The production system 15 may in turn conceptually be viewed as including one or more components that contribute towards the agricultural production outputs 16 . These components may include production units 18 , production practices 20 , inputs 22 , biological processes 24 , and time 26 . The outputs 16 may include agricultural products 28 and impacts 30 on environmental, economic and social systems. [0037] For the purposes of the present specification, agricultural systems 10 shall be taken to include, but not be limited to, land-based (e.g., cropland, grassland, pasture and range, forest land, plantations, hen-house, etc.), water-based (e.g., oceans, lakes, rivers, streams, ponds, tanks, etc.), fermentation (e.g., winemaking, brewing, baking, etc.), biochemical (e.g. extraction or biosynthesis of proteins, vitamins, minerals, amino acids, etc.), chemical (e.g., distilling, etc.) or other production processes and actions to prepare agricultural products for ingestion or use by a human, animal, or plant. [0038] Agricultural products 28 may be taken to include, but not be limited to, grains, beans, vegetables, fruits, nuts, meats, poultry, eggs, fish, seafood, herbs, beverages, wine, beer, distilled spirits, flowers, nursery plants, proteins, amino acids, vitamins, minerals, nutraceuticals, nutritional supplements, medicines, plant and animal derived oils, cotton, fiber, paper, milk, cheese, breads, leather, and other processed products. [0039] Units 18 may include, but not limited to, a specified unit of cropland (e.g., agricultural field), forest land (e.g., natural forest, managed forests, plantations, etc.), grassland pasture and range used by grazing animals, animal rearing and processing facilities (e.g., feed-lot, slaughter-house, hen-house, etc.), a defined fresh or salt water area where fish, seafood and other plants and animals are captured or otherwise collected (e.g., specified length of ocean-front coast, lake-front coast, lake, river, stream, pond, bay, open-ocean, lake, aquaculture tank, etc.), processing facility (e.g., fermentation plant, dehydration plant, mixing plant, distillery, kitchen, bakery, bottling plant, canning plant, etc) or tank, barrel, vat, or other fermentation, biochemical, or chemical chambers. A unit may also be a biologically meaningful unit (e.g., an ecosystem, watershed, biological community, habitat, or species population range), a politically meaningful unit (e.g., a country, state, region, county, city, town, village or other voting unit) or a geographically meaningful unit (e.g., a section, township, and range). [0040] The terms agricultural product processing or food processing mean herein any operation or action made to prepare an agricultural product 28 for ingestion or use by a human, animal, or plant. [0041] The terms farm, ranch, forest operation, fishing operation, and processing facility include herein an agricultural production venture, enterprise, operation, location, site or other point of origin, wherein or whereby an agricultural, chemical or biochemical process is sponsored, effected or managed and that produces an agricultural product 28 that is meant to be, or is likely to occasionally be, used or ingested by a human, animal, or plant or is meant to be combined with other materials in subsequent processes or mixtures, whereafter one or more resultant products or derivative products of a subsequent process, are meant to be, or are likely to be occasionally be, used or ingested by a human, animal, or plant. The meaning of the terms farm, ranch, forest operation, fishing operation, and processing facility further include an agricultural production venture, enterprise, operation, location, site or other point of origin, wherein or whereby an agricultural product 28 that is meant to be, or is likely to occasionally be, used in a subsequent agricultural, industrial, chemical, biochemical or commercial process or manufacture, is generated or sponsored. Examples of a farm, ranch, forest operation, fishing operation, and processing facility include vineyards, wineries, orchards, vegetable garden's, vegetable farms, ranches, pig farms, chicken farms, meat packing plants, fish cannery, vegetable cannery, freezing facilities, drying facilities, bakery, extraction facilities, biosynthesis facilities, egg farms, fish hatcheries, aquaculture facilities, tree and plant nurseries, forests, plantations, and fresh water and salt water fishing areas and locations. [0042] The term lot is defined as two or more agricultural products 28 that originate from the same unit of production 18 . Further, agricultural products 28 of a lot may be harvested or processed in substantially the same way during substantially the same time period with substantially the same procedures and equipment. A unique alphanumeric identifier or other suitable designation known in the art is used to identify a lot. Examples of lots include, but are not limited to, two apples harvested from the same tree on the same field on the same day or during another designated time period, a volume or an amount of grapes harvested from a particular area of a specific vineyard during a certain time period, lettuce heads harvested from the same field during the same time period, a volume of wine fermented in a single barrel or vat, a volume of wine divided and placed into a plurality of bottles, canned fruit, vegetables, or meat manufactured on the same day or during another designated time period on the same assembly line, frozen fruit, vegetables, or meat manufactured on the same day or during another designated time period on the same assembly line. [0043] Production practices 20 are practices employed, for example, by farm, ranch, forest operation, fishing operation, and processing facility managers to combine production units 18 , inputs 22 , biological processes 24 , and time 26 to produce the agricultural products 28 . Examples of production practices 20 may include, but are not limited to, crop residue management, cropping management, pest management, nutrient management, soil management, water management, human resource management, fermentation management, quality control management, biochemical process management, etc. [0044] Inputs 22 may include but are not limited to production inputs (e.g., nutrients, pesticides, seeds, seedlings, bacterial strains, yeast strains, energy, machinery and other technologies, water, etc.), management inputs (e.g., farm managers, facility managers, boat or fleet managers, product line manager, quality control managers, pest managers, etc.), labor inputs (e.g., farm worker, ranch-hand, factory worker, production line worker, etc.), and capital inputs that are in any way used in the production of agricultural products 28 . [0045] Biological processes 24 include, but are not limited to biologically meaningful physical, chemical, biochemical, individual organism, population, community, watershed, ecosystem, and biosphere processes that influence in a positive or negative manner the production of agricultural products 28 and impacts 30 . The biosphere is the largest biological unit and includes all parts of the earth where life exists. Several key nutrients and inorganic molecules essential for life cycle on a biosphere scale. Examples include the water cycle, nitrogen cycle, and carbon cycle. The term ecosystem refers to communities of interacting organisms and the physical environment in which they live. Example ecosystems include grassland, forest, freshwater, coastal, and agricultural. Ecosystem processes include such functions as air and water purification, evaporation, precipitation, soil production, soil erosion, climate control, ecosystem-level nutrient cycling, and the capture and flow of energy via food chains and food webs. [0046] Ecosystems are composed of smaller biologically meaningful units including watersheds, communities, populations, and individual organisms. A watershed is a geographically defined area where water from streams, neighborhoods, agricultural areas, and rivers carries sediments and dissolved materials to a common outlet such as a wetland, estuary, lake, pond, sea or ocean. Communities are the assemblages of species populations that occur together in space and time. Species diversity, community biomass and productivity, succession, community-level nutrient cycling and energy flow, interspecific competition, decomposition, mutualism, predation, and parasitism are examples of community properties. Populations are composed of groups of actually or potentially interbreeding individuals at a given locality. Example population processes include reproduction, gene flow, intraspecific competition, and dispersal. Individual organism processes include growth, fitness, reproduction, maintenance, and survival. Biochemical processes include such examples as photosynthesis and metabolism. [0047] Impacts 30 may include, but are not limited to, intended and unintended alternations to biological, economic and social processes and systems as a result of agricultural production system 15 . The term biological impact is herein defined as an unintended or intended impact of agricultural production system 15 on biological processes and conditions. The agricultural production system 15 can have impacts on air, water, and land from pollutants (e.g., sediment, dust and other particulate matter, nutrients, pesticides and their breakdown products, other organic and inorganic chemicals, salts, pathogens, etc.) and use patterns (e.g., cultivation, deforestation, wetland drainage, burning, changes to water flows, etc.) that may alter physical, chemical, biochemical, individual organism, population, community, watershed, ecosystem, and biosphere processes. Example physical impacts include alternations to soil, water, or air temperatures, changes in light intensity on land or water surfaces, water turbidity, etc. Example chemical impacts include alternations to soil or water pH, percent dissolved oxygen in water, concentration of particulate matter in air, concentration of minerals (e.g., nitrogen, phosphorous, selenium, etc.) in soil or water, and contamination of soils or water by inorganic or organic pollutants (e.g., pesticides, fertilizers, pesticide-breakdown products, etc.). Examples of impacts on individual organisms include altered growth, fitness, reproduction, maintenance, and survival. [0048] Examples of impacts on species populations include significant reduction in overall numbers (e.g., endangered or threatened species status), significant increases in overall numbers and range (e.g., invasive species), and alternation of population age, genetic structure and diversity. Examples of community impacts include alterations of species diversity and abundance (e.g., invasive species, loss of wild populations, etc.), changes in the structure and functioning of food chains and food webs, and changes in nutrient cycling and energy flows. Examples of ecosystem impacts include alternations in water quality, water quantity, water duration, and water seasonal timing, large-scale changes in species diversity and abundance, decreases in total biomass and productivity, and alternations in nutrient cycling and energy flow. Examples of biosphere impacts include alternations to the carbon cycle (e.g., increased carbon dioxide in the atmosphere), nitrogen cycle (e.g., increased nitrates in deep ground water) and global climate change. [0049] The term economic impact is herein defined as an unintended or intended impact of an agricultural production system 15 not accounted for in the trade value or sale price of agricultural product 28 . The term social impact is herein defined as an unintended or intended impact of an agricultural production system 15 on the health, safety, educational, and standard of living conditions and opportunities of individuals and communities and the treatment of animals. Example economic impacts resulting from agricultural production systems 15 include the individual, community, and government cost of additional water treatment to remove agricultural pollutes (e.g., sediments, nutrients, pesticides, pathogens, etc.), increased health care costs associated with pesticide poisonings, increased taxes to pay for air quality and water quality regulatory oversight and clean-up. Examples of social impacts that may result from agricultural production system 15 include poverty from low paying and season jobs, limited availability of affordable and safe housing, dangerous working conditions (e.g., exposure to pesticides), limited opportunities for education or training, decreased consumer confidence in safe and affordable agricultural products 28 , inhumane treatment of animals, and increased regulatory oversight. [0050] FIG. 2 illustrates how seasonal production systems 15 can be managed as long-term production systems 17 and seasonal production systems 15 deliver seasonal production impacts 30 and long-term production impacts 31 . Examples of long term production systems 17 include crop rotation, changes in cropping patterns, etc. Examples of long term production impacts 31 include accumulated environmental, economic and social impacts such as siltation of water courses, groundwater pollution, decreases in biodiversity, and decreases in quality of life for individuals and communities. Overview—Methodology [0051] FIG. 3 is a flow chart providing an overview of an exemplary method 40 of capturing, managing, processing and outputting data pertaining to an agricultural product. At a high level, the method 40 may conceptually be viewed as composing a data capture and chain of custody record creation component 42 , a certification/accreditation/compliance component 44 and a reporting component 46 . Contributors, processors and users of the data concerning the agricultural product include custodians 48 of the agricultural product, an agricultural management information system 50 , a regulatory/certification/accreditation authorities 52 , consumers 54 of the agricultural product 28 , and agricultural managers 56 . [0052] The method 40 commences at block 58 with the capture, by custodians 48 of an agricultural product 28 , of product data pertaining to the agricultural product, the product data reflecting a condition pertaining to the product at a custodial location. In one embodiment, as will be described in further detail below, a series of custodians, each controlling a custodial location along a chain of custody, perform data capture operations to capture product data reflecting conditions pertaining to the product at each of the respective custodial locations. [0053] At block 60 , a data record is created by each custodian 48 , the record embodying the product data captured at block 58 . [0054] At block 62 , the created data record is communicated from a respective custodian 48 to the agricultural management information system 50 that, at block 62 , proceeds to store the received data record together with an internal identifier 64 . [0055] At block 66 , the agricultural management information system 50 performs a certification process to create and store a certification record indicating that a particular agricultural product, for which data has been received from one or more custodians 48 , complies to one or more certification or accreditation standards specified by one or more certification or accreditation authorities. This certification record may, at block 68 , be communicated to the relevant certification or accreditation authority, that, at block 70 , may optionally generate a certification or accreditation report. [0056] At block 72 , the agricultural management information system 50 may optionally perform a regulatory compliance process to create and store a compliance record. At block 74 , this compliance record may optionally be transmitted to, a regulatory compliance authority that then generates, at block 76 , a regulatory compliance report. [0057] At block 78 , a consumer 54 may generate a request for certain information regarding an agricultural product (e.g., whether the product complies with certain certification standards). As will be described in further detail below, this request may be inputted into a network communication device (e.g., a network-coupled personal computer) which is then communicated to the agricultural management information system 50 . [0058] At block 80 , the agricultural management information system 50 retrieves data pertaining to one or more agricultural products identified in the consumer request and, at block 82 , transmits the received data to the consumer 54 as a response to the initial request. At block 84 , the consumer 54 may then view the product data including, for example, certification/accreditation/compliance information as well as custodial history information as derived from the data originally captured by the custodians 48 at block 58 . [0059] In a similar manner, at block 86 , an agricultural manager 56 may generate a report request for a report pertaining to one or more agricultural products, this request being transmitted to the agricultural management information system 50 at block 88 . At block 90 , the agricultural management information system 50 retrieves one or more reports and other pertinent data and, at block 92 , transmits the retrieved report data to the agricultural manager 56 . At block 94 , the agricultural manager 56 is then able to view one or more management reports derived from the management data. [0060] FIG. 3 provides a high-level overview of the method 40 . Further details regarding each of the operations, as well as the systems underlying such operations, will now be discussed. Data Capture and Chain of Custody [0061] FIG. 4 is a diagrammatic representation of the exemplary capture of data at multiple units 100 that together constitute a chain of custody. The submission, by each of such units 100 , to the agricultural management information system 50 for storage within a database 103 , of records 102 that embody the captured data pertaining to the agricultural product. The units 100 may conceptually be viewed as comprising units of production 104 , and units of processing, storage and distribution 106 . Within the context of each unit, data may be captured regarding each of a number of operations to generate individual data records of product data reflecting conditions pertaining to a relevant agricultural product at a respective unit. For example, a unit of production 104 , as defined above with reference to FIG. 1 , may include pre-production operations 108 , production operations 110 and processing operations 112 . According to an exemplary embodiment of the present invention, data pertaining to agricultural products at the relevant unit of production 104 may be gathered as part of the operations 108 - 112 to compose the data records 102 . The exemplary records 102 are shown to include location data to indicate the location of the relevant unit of production, measured data reflecting a measured or otherwise ascertained metric, time and date information, and authentication information. [0062] Similarly, each of a number of units of processing, storage and distribution 106 may include combinations and permutations of processing operations 112 , storage operations 114 and transport operations 116 , agricultural product data being captured as part of such operations. [0063] While the described operations are illustrated in FIG. 4 as being performed at various units, it will be appreciated that any permutation, variation or combination of the described operations may occur at any of the described units, and that the data capture need not necessarily be performed as part of the described operations. [0064] By implementing the capture of product data at each of a chain of units that constitute a chain of custody of an agricultural product and the submission of such product data to the agricultural management information system 50 , for example in the form of the records 102 , it will be appreciated that the agricultural management information system 50 is able to provide a global view of a chain of custody and conditions pertaining to the agricultural product at each custodial location constituting the chain of custody. [0065] FIG. 5 is a diagrammatic representation of a data record 102 , according to an exemplary embodiment of the present invention, that may be generated by a data capture device at each of the units 100 of a chain of custody and communicated to the agricultural management information system 50 . In one embodiment, the record 102 may be constructed by the data capture device at the custodial location, and communicated to the agricultural management information system 50 as a record. In an alternative embodiment, the agricultural product data, as captured by the data capture device, may simply be communicated to the agricultural management information system 50 , which then formats the received data as the record 102 . [0066] A unique identification field 120 stores, for each record, a unique identifier for the particular record that also serves to identify the relevant agricultural product for which the record 120 pertains. In one exemplary embodiment, a unique identifier for a record stored in a field 120 may comprise a Universal Product Code (UPC), or a derivative thereof. [0067] A time field 122 , for each record 102 , stores a time at which the agricultural product data included within the record 102 was captured. A date field 124 similarly stores a date on which the relevant data was captured. A place field 126 stores location data indicating a location (e.g., any one of the units 100 discussed above with reference to FIG. 4 ) at which the agricultural product data was captured. In one embodiment, the data in the place field 126 indicates one of multiple custodial locations for a particular agricultural product. [0068] A person field 128 stores an identifier for a person, or operator, at a custodial location who was responsible for the capture of the agricultural product data. An activity field 130 may store information identifying an activity (e.g., any one of the operations 108 - 116 described above with reference to FIG. 4 ) pertaining to the agricultural product and to which the captured data pertains. For example, an activity indicated in the activity field 130 may be the application of a fertilizer to a unit of production, the applying of the pesticide at a unit of production, the harvesting of an agricultural product, the packaging of an agricultural product, etc. [0069] An equipment serial number field 132 stores an identifier for data capture equipment utilized in the capture of the data embodied within the record 102 . For example, the equipment may comprise a hand-held device, examples of which are provided below. A custodian field 134 stores an identifier of a custodian 48 that operates or manages a particular custodial location in a chain of custody (e.g., a unit 100 ). [0070] The record 102 may also include a number of optional verification identifiers. More specifically, a digital signature field 136 may store a digital signature utilized to encrypt the record 102 for secure and confidential transmission. A witness field 138 may include a digital witness identifier that provides a further level of authentication for the digital signature 138 . A Global Positioning System (GPS) field 140 may include longitudinal and latitudinal location information, in one embodiment, to be utilized to authenticate place information stored within the place field 126 . The contents of the GPS field 140 may also be utilized to enhance reports generated by the agricultural management information system 50 , by providing a further level of detail regarding location of a custodial location. [0071] FIG. 6 is a block diagram illustrating a compliance and chain of custody system 150 that includes a chain of custody constituted by a collection of custodians 48 , each of which provides input, for example in the form of a record 102 , to the agricultural management information system 50 . The system 150 is also shown to include a collection of regulatory/certification/accreditation authorities 52 that interact with the agricultural management information system 50 to at least partially automate regulatory compliance, certification or an accreditation processes. The exemplary custodians 48 include an agricultural production system 15 , a packaging custodian 152 , a transportation custodian 154 , a processor custodian 156 , a wholesale custodian 158 and a retail custodian 160 . Outside the chain of custody, a consumer 54 is also shown to interact with the agricultural management information system 50 . [0072] Each of the custodians 48 is further shown to access one or more data capture devices 170 that are utilized to capture product data at the respective custodial locations 48 . Each data capture device 170 is furthermore shown to be in communication with the agricultural management information system 50 , so as to facilitate the communication of the captured product data from the data capture device 170 to the agricultural management information system 50 . [0073] A data capture device 170 utilized by a custodian 48 may be a hand-held device (e.g., a Personal Digital Assistant (PDA), a mobile telephone, or any other known hand-held device), or a fully-functional computer system (e.g., a desktop Personal Computer (PC) or a notebook computer system). Further, as described in further detail below, the data capture device 170 , according to an exemplary embodiment of the present invention, may be equipped to perform read and/or write operations of an external information source. In one embodiment, the data capture device 170 may be connectable to an external data source associated with a particular custodial location. In alternative embodiments, the data capture device 170 may be constructed to perform a wireless read of information associated with a custodial location utilizing any electromagnetic frequency communications (e.g., optical, infrared (IR) or radio frequency (RF) communications). [0074] The agricultural management information system 50 , as will be described in further detail below, comprises one or more applications executing on one or more computer systems; as well as one or more databases maintained on one or more data storage systems. [0075] The data capture devices 170 communicate with the agricultural management information system 50 utilizing a communications network, such as the Internet, the Plain Old Telephone Service (POTS), cellular telephone networks, a Wide Area Network (WAN) or a Local Area Network (LAN). [0076] A collection of authorities 52 are also shown to interact with the agricultural management information system 50 . Such authorities 52 include, merely for example, a certification authority 162 (e.g., The Food Alliance, California. Certified Organic Farmers, etc.), an accreditation authority 164 (Marine Stewardship Council, Forest Stewardship Council, etc.), a non-profit organization 166 (e.g., an environmental watchdog, social, economic organization, or universities), and federal, state, and local public agencies 168 (e.g., The US Environmental Protection Agency (EPA), The Food And Drug Agency (FDA), The US Department of Agriculture (USDA), California Department of Pesticide Regulation (DPR), etc.). The interaction of the authorities 52 with, the agricultural management information system 50 will also be described in further detail below. Data Capture [0077] Further details regarding exemplary embodiments of the capture 42 of data concerning an agricultural product will now be described. [0078] FIG. 7 is a diagrammatic representation illustrating a plurality of data capture devices 170 , connected via a network 180 (e.g., the Internet) to each other and to the agricultural management information system 50 . Each of the data capture devices 170 is located at a respective custodial location 48 within a chain of custody to capture pertinent data. The data capture devices 170 also include a stand-alone computer system 184 that communicates agricultural product information on a data storage media 186 (e.g., a CD ROM or any other optical, magnetic or opto-magnetic storage medium) that is provided to the agricultural management information system 50 . Accordingly, the computer system 184 is not required to be coupled to the network 180 . [0079] One of the data capture devices 170 is shown to comprise a hand-held device 182 that communicates utilizing radio-frequency communications 190 with a base computer system 192 . The hand-held device 182 is also shown to communicate directly with the network 180 via radio-frequency communications 190 . The hand-held device 182 is utilized by an operator conveniently to record data concerning an agricultural product at various locations within a chain of custody and production cycle through which the agricultural product proceeds. The hand-held device 182 may be utilized by any of the custodians 48 , described above with reference to FIG. 6 , at any one of the custodial locations 48 . For example, farmers, transporters (e.g., truckers and railroad freight handlers) processors, distributors, retailers, insurers, marketers, resellers, regulatory agents, inspectors, environmentalists and any third party may utilize a hand-held device 182 to capture appropriate data. [0080] The hand-held device 182 , and also the computer systems 181 , includes a data reader in the exemplary form of a barcode reader 194 . An alternative embodiment of the present invention, the data reader may include any optical, infrared, radio frequency, magnetic or opto-magnetic reader or a network device before receiving communications or information via a network. [0081] FIGS. 8A-8D are diagrams illustrating further details regarding the operation of an exemplary hand-held device 182 , that receives input from a barcode reader 194 . Data capture at an exemplary custodial location in the form of a production unit will now be described with reference to FIGS. 7 and 8 A- 8 D. [0082] Turning firstly to FIG. 7 , the present invention proposes a method by which product data, reflecting a condition pertaining to an agricultural product, be associated with location data identifying a location within the chain of custody. Further, the present invention proposes that a product identifier may also be associated with the captured location and product data. Referring specifically to FIG. 7 , at a specific custodial location 201 , location data in the form of location code 202 , encoded as a barcode, is shown to be physically associated with the custodial location 201 . For example, as shown in more detail in FIG. 8B , the location code 202 may be printed on a weather-resistant tag 210 that is fixed to a physical structure in the exemplary form of a post 212 located at the custodial location 201 . Accordingly, the post 212 may be positioned at a specific location at a custodial location 201 to provide a reference location for the capture of product data. [0083] FIG. 8C illustrates an exemplary situation in which a tag 210 , on which the location code 202 is again represented in the form of a barcode, is attached to an insect trap 214 . [0084] It will be appreciated that, utilizing the barcode reader 194 , the hand-held device 182 may be utilized conveniently and reliably to capture a location code 202 from a location identifier (e.g., the tag 210 ) that is physically associated with a custodial location 201 by being attached to a post or trap, or being otherwise secured at the custodial location 201 . [0085] Having captured location data utilizing the hand-held device 182 , the present invention proposes allowing a custodian 48 to capture product data, reflecting a condition pertaining to an agricultural product, at the relevant custodial location 201 . To this end, FIG. 8A shows the hand-held device 182 to include a keypad 216 via which a custodian 48 may enter product data reflecting a condition pertaining to the product at the first location identified by the relevant location code 202 . For example, with reference to FIG. 8C , a display screen 218 of the hand-held device 182 may present a user interface via which, utilizing the keypad 216 , or touch-sensitive functionality provided by the screen 218 itself, the custodian 48 may enter an indication of the number of bugs 220 captured in the trap 214 at a particular time. It will be appreciated that, within different environments and at different custodial locations 201 , a wide variety of agricultural product data may be captured. Accordingly, a wide variety of data capture applications may be executed by the data capture device (e.g., the hand-held device 182 ) to prompt a custodian 48 for appropriate data in a convenient and reliable manner. Such prompting may occur via a user interface presented on the display screen 218 . The data input may be via the keypad 216 , or via a touch screen functionality. [0086] In a further alternative embodiment, referring to FIG. 80 , a particular custodian 48 may be provided with a chart 222 , or handbook, of barcodes, each barcode embodying a product data code 204 that is associated with a particular chart 222 . For example, each product data code 204 contained within a particular chart 222 may reflect a unique condition that is observable or determinable by a custodian 48 . For example, a product data code 204 may reflect an observed condition pertaining to an agricultural product at a custodial location identified by the location code 202 . It will be appreciated that a wide variety of conditions may be of interest from an agricultural management perspective, and any one of these conditions may be associated with a particular product data code 204 . FIG. 8E illustrates an exemplary chart 222 on which are printed a collection of barcodes. The collection of barcodes includes product data codes 204 that in the illustrated embodiment provide product data in the form of a numeric count of pests that may be observed within a trap 214 , such as that illustrated in FIG. 8C . Utilizing a barcode reader 194 , such as that illustrated in FIG. 8A , a custodian 48 may conveniently input a numeric value to a hand-held device 182 . It will readily be appreciated that by selecting a sequence of the product data codes 204 , any numeric value may conveniently be entered into a hand-held device 182 . [0087] In addition to the product data codes 204 , the chart 222 includes examples of location/data type codes 205 , each of which indicates both a data type (e.g., leafhopper count, mite count, thrips count, mildew levels) and a particular location at which the relevant data type was captured (e.g., the northwest, northeast, southwest or southeast region of a unit or production). Utilizing the location/data type codes 205 , a custodian 48 is conveniently able, by performing a single read of a code 205 , to input both location and data type information to a hand-held device 182 , whereafter a count, that comprises the indicated data type, may be entered utilizing the product data codes 204 . [0088] It will of course be appreciated that, in alternative embodiments, the location and data type codes may be distinct. For example, the chart 222 may contain a first set of data type codes (e.g., leafhopper, mite, thrips, mildew), a second set of location codes (e.g., northwest, northeast, southwest and southeast) and a third set of product data codes 204 . In this embodiment, it will be appreciated, the number of barcodes printed on a chart 222 may be advantageously reduced. However, it will be appreciated that data input would, utilizing this embodiment, require the input of three codes, as opposed to the two codes that are advantageously required for a complete input utilizing the chart 222 illustrated in FIG. 8E . [0089] The chart 222 is also shown to include a collection of command codes 207 utilizing which a custodian 48 may conveniently input commands (e.g., “done with vineyard”) into a hand-held device 182 . It will be appreciated that any number of commands, applicable to a particular application or environment, may appear on a chart 222 . [0090] Having captured the location data (e.g., the location code 202 ) and the product data (e.g., the product data code 204 ), a custodian 48 may where appropriate and possible capture product identification data as embodied within a product identification code 206 (e.g., a Universal Product Code (UPC)) embodied within a barcode associated with a particular agricultural product as illustrated in FIG. 7 . It will be appreciated that a product identification code 206 may not be, associated with an individual product at all locations along a chain of custody, and may only become associated with an individual product and during a packaging stage. For example, at a unit of production 18 (e.g., a farm unit producing thousands of lettuce heads), a product identification code 206 is not associated with each individual agricultural product. However, at a downstream packaging custodian 152 , such product identification codes 206 may be associated with each individual agricultural product. [0091] In one embodiment of the present invention, the record 102 described above with reference to FIG. 5 is composed by the hand-held device 182 . In an alternative embodiment, the information to compose the record 102 is communicated from the hand-held device 182 to a computer system 181 , that composes the record 102 . In a further embodiment, the information captured by the hand-held device 182 is simply relayed via the computer system 181 to the agricultural management information system 50 that then composes the record 102 . In a further embodiment, the information captured by the hand-held device 182 is communicated via wireless transmission directly to the agricultural management information system 50 that then composes the record 102 . In any event, it will be appreciated that, to compose the record 102 , information types to populate the various fields, should be captured. Accordingly, the hand-held device 182 is required to capture information to populate the fields of the record 102 , either automatically or by prompting input of the appropriate data. While the capture of the data for the record 102 is described as being performed by the hand-held device 182 above and below, it will be appreciated that the information could similarly be captured by any of the computer systems 181 illustrated in FIG. 7 to which a reader (e.g., a barcode reader 194 ), may be attached, and into which information may be inputted via a keyboard or a cursor control device, responsive to prompting presented on a display screen of the computer screen 181 . However, for the purposes of illustration, the description herein shall be limited to data captured via the hand-held device 182 . [0092] FIG. 9 is a block diagram illustrating the hardware components of the hand-held device 182 , according to an exemplary embodiment of the present invention. A processor 230 is coupled via buses to a Random Access Memory (RAM) 232 , a static memory 234 and a storage device 236 (e.g., a disk drive or flash memory device). The display screen 218 also receives signals from the processor to generate a display (e.g., a user interface to receive agricultural product data). [0093] The hand-held device 182 is powered by an internal power source 238 (e.g., batteries), and also has a digital signature module 240 to store a digital signature that uniquely identifies the hand-held device 182 . A network modem or port 242 (e.g., a USB or FireWire port) allows the hand-held device 182 to be coupled to a network. A receive/transmit module 244 enables the hand-held device to transmit and receive optical (e.g., infrared), radio frequency or any other electromagnetic frequency signals. [0094] The hand-held device 182 is also shown to include at least one input module 246 via which a custodian may input data into the hand-held device 182 . The input module may comprise the keypad 216 , a touch-screen capability associated with the display 218 , a voice recorder, a video recorder, an optical code recognition (OCR) module or radio frequency module associated with the receive/transmit module 244 , the barcode reader 194 or any other hardware module that facilitates the input of data into the hand-held device 182 . [0095] An external power source 248 may also be utilized to provide power to the hand-held device 182 . An optional GPS module 250 may provide longitudinal and latitudinal position information to the hand-held device 182 . In an alternative embodiment, the hand-held device 182 may include a relative position system (e.g., a three-point transponder) that detects the location of the hand-held device 182 relative to a base unit (e.g., associated with the computer system 192 ), the base computer system 192 including a GPS module. By combining the relative positioning information received from the hand-held device 182 with the location information derived by a GPS module of the base computer system 192 , position information for the hand-held device 182 may be derived. [0096] FIG. 10 is a block diagram illustrating system components implemented, for example, in software within the hand-held device 182 . The hand-held device 182 is shown to include a number of subsystems, including an operating system 260 , a storage system 262 that controls the RAM 232 , the static memory 234 and the storage device 236 , and a verification system 264 that verifies data inputted into the hand-held device 182 via the input modules 246 . Specifically, the verification system 264 may verify location data, as represented by a location code 202 , inputted via the barcode reader 194 . To this end, the verification system 264 may receive input from the GPS module 250 or location transponder 252 . Further, the verification system 264 may operate to verify the authenticity and trustworthiness of the inputted data by receiving a witness confirmation 266 of the inputted data. In this embodiment, a witness with a unique identifier 138 confirms some or all data captured by the operator of the hand-held device 182 and adds a unique witness identifier 138 to the captured data or data report 102 prior to transmission to the agricultural management information system 50 . Such witnesses may include a second custodian, certification agent, accreditation agent, third-party representative, or government agent. A data capture system 268 controls the one or more input modules 246 , and may interface with a number of specific subsystems, namely a voice recognition system 270 , a handwriting recognition system 272 , an OCR system 274 and a IR or RF system 276 . Any one of the systems 270 - 276 may be dedicated at the controlling of a specific input module 246 . A processor and memory system 278 operates to control the processor 230 and the memory 234 . [0097] A report generation system 280 , in one embodiment, operates to generate a report or record from the data received from the data capture system 268 , as well as data retrieved internally from other systems and subsystems of the hand-held device 182 . To this end, a date and time system 282 provides date and time information to the report generation system 280 . Further, the storage device 236 , in one embodiment, stores identification information identifying a person (or process) that is responsible for the input of the data via the one or more input modules 246 and also that stores an equipment serial number associated with the hand-held device. [0098] A transmission system 284 is responsible for operating the network modem/port 242 and the receive/transmit module 244 to facilitate the output of information from the hand-held device 182 . In one embodiment, the transmission system 284 may transmit captured data utilizing RF communications to a base computer system 192 that then, via the Internet, communicates this data to the agricultural management information system 50 . In an alternative embodiment, the hand-held device 182 may be physically coupled to the base computer system 192 in order to transfer information to the base computer system 192 for propagation to the agricultural management information system 50 . In yet a further embodiment, the hand-held device 182 may be coupled directly to the Internet, and may itself communicate the captured data to the agricultural management information system 50 . Data Capture—Methodology [0099] FIG. 11 is a flow chart illustrating a method 300 , according to an exemplary embodiment of the present invention, of capturing data pertaining to an agricultural product. The method 300 commences at decision block 302 , with the determination as to whether a record or report generated by the report/record generation system 280 , and composed of the previously captured data pertaining to an agriculture product, is to be stored. If so, at block 304 , the report, or record, is stored. Following a negative determination at decision block 302 , at decision block 306 , a determination is made as to whether input data has been received via one of the input modules 246 of the hand-held device. If not, a wait state is entered at block 308 . [0100] On the other hand, if input data is detected at decision block 306 , at block 310 the hand-held device accepts location data in the form, for example, of a location code captured from a location identifier (e.g., a tag 210 or a chart 222 having a printed barcode thereon). Alternatively, the location data may be automatically determined utilizing OCR technology, with a location code composing a numeric sequence read from a location identifier [0101] In yet another alternative embodiment, a location code may be embedded in a transponder that is activated by the hand-held device 182 , so the location code is communicated as a radio frequency communication from the transponder to an appropriate receiver embedded within the hand-held device 182 . [0102] It will of course be appreciated that the location data can be communicated to the hand-held device 182 in any one of a number of ways from media on which the location data is stored in such a way as to be physically associated with a location identified by the location data. By obtaining the location data from media that is physically associated with the relevant location, the integrity of this information and the reliability of the capture operation, may be increased. Furthermore, the convenience to a custodian 48 performing the location data capture is increased. By having the location data appear, or be stored, on a media at the relevant custodial location, a relatively low-tech and cost effective system for capturing the location data is provided. [0103] At block 312 , the hand-held device 182 accepts agricultural product data, for example in the form of a product data code 204 as describe with reference to FIGS. 8D and 8E . Alternatively, the product data may be inputted into the hand-held device via the keypad 216 or a touch- (or pressure) sensitive display 218 . At block 312 , product identification data 206 , as described above with reference to FIG. 7 , may also optionally be inputted if such information is available. [0104] At decision block 314 , a determination is made as to whether further external data input is required in order to complete a report or record to which the hand-held device 182 contributes. If so, the method 300 loops back to block 312 to receive further data. If not, at decision block 316 , the method 300 again loops back to block 312 . Alternatively, if the collection of information by the device 182 is deemed to be finished at decision block 316 , at block 318 the device 182 may append a digital signature to the data, at block 320 append time and date information to the captured data, at block 322 include a geographic position reference, such as a GPS value or other suitable geographic positioning identifier, to the data, and at block 324 append witness information to the data. It should be noted that the addition to the data of the digital signature, time and date stamp, geographic position reference and witness verification may optionally be performed, and serves to enhance the perceived credibility of the information as entered a custodian. Further, this optional data may serve to address or satisfy a certain regulatory, accreditation, or certification requirements. [0105] At decision block 327 , a determination is made as to whether the report/record is to be transmitted. If so, a transmission occurs at block 328 . [0106] At decision block 330 , a determination is made as to whether the record/report is to be stored. If so, a storage operation occurs at block 332 . [0107] The acceptance of the location and product data at blocks 310 and 312 , as previously noted, may be through an optical, radio frequency, infrared, video, or audio signal read operation of an appropriate code. For example, a product or data code may be stored in a one, two or multi-dimensional barcode. Alternatively, a product or data code may be stored within a transponder, or by a radio frequency transmitter that communicates utilizing, for example, the BlueTooth protocol. In yet a further exemplary embodiment, a location or data code may be encoded as an audio signal. [0108] The product data captured at block 312 may comprise any data pertaining to an agricultural product. For example, the product data may be environmental data, indicating environmental conditions associated with an agricultural product. Such environmental data may, for example, reflect growing environment and conditions (e.g., soil nutrient levels, atmospheric conditions, pesticide application, etc.). Environmental data may also include conditions such as water, air and land quality adjacent to the unit of production 18 . Environmental data may further comprise the health and status of species populations, a community, watershed, and ecosystem associated with the unit of production 18 . The product data may also include characteristic data indicating a specific characteristic of an agricultural product. For example, such characteristic data may indicate the size, weight, calorie, color, brix, or other observable or measurable characteristic of an agricultural product. The product data may also comprise activity data recording details of an activity performed with respect to an agricultural product. For example, the activity data may reflect the timing and volume of pesticides applied at a particular unit of production 18 . The activity data could also reflect data concerning any processing, distributing, packing, treating or handling of the agriculture product at any one of the custodial locations discussed above. [0109] The product data may furthermore include economic data indicating costs of production associated with an agricultural product (e.g., material, water, energy, equipment, management, land, capital, and labor costs). Further, labor (or personnel) data may be captured at block 312 to identify personnel that contributed toward the production or processing of the agricultural product. Such personnel or data may include personnel identification, labor location and labor time, merely for example. [0110] It should also be noted that the product data captured at block 312 may comprise audio or video data that is captured into a portable data capture device (e.g., an audio cassette recorder or a video recorder). Such captured audio or video may be digitized, and stored by the agricultural management information system 50 as part of the record 102 . Chain of Custody—Database [0111] FIG. 12 is a block diagram illustrating an exemplary collection 400 of data records 102 that may be maintained within the database 103 of the agricultural management information system 50 . FIG. 12 also illustrates that the collection 400 of records 102 may be indexed by a common product code (e.g., a Universal Product Code (UPC) 402 or a lot code 404 ). Specifically, the UPC 402 or the lot code 404 may comprise the unique identifier 120 of an agricultural product data record 102 , as illustrated in FIG. 5 . Each of the records 102 may be linked to further records and reports pertaining to a specific agricultural product, or agricultural product lot, so that a hierarchical data structure of records and reports that comprises the collection 400 is defined. An exemplary chain of custody 406 for an agricultural product is also illustrated in FIG. 12 . In addition to records 102 that are generated at various custodial locations along the chain of custody 406 , the collection 400 may also include reports 408 for various authorities (e.g., regulatory, accreditation, certification). For example, a first set of reports 410 may be generated for an organic certification authority based on information contained in the records. A further set of records 412 may be generated for a non-profit watchdog organization, and yet another set of reports 414 generated for a regulatory authority (e.g., the EPA). Each of the reports 408 may furthermore have one or more lot codes 404 and one or more UPCs 402 associated therewith. The generation of the exemplary reports 408 will be described in further detail below. Architecture—Agricultural Management Information System 50 [0112] FIG. 13 is a block diagram illustrating further architectural details of the agricultural management information system 50 , according to an exemplary embodiment of the present invention. The agricultural management information system 50 is shown to receive data records 102 , including at least location and product data, from custodians 48 , automated data capture mechanisms 450 , and other submitters 452 . In an alternative embodiment, raw data may be received at the agricultural management information system 50 , which then itself composes the record 102 . [0113] The agricultural management information system 50 is shown to include a certification server 454 that is responsible for generating reports utilizing records, pertaining to an agricultural product, obtained from custodial locations constituting a chain of custody for the relevant agricultural product. To this end, FIG. 13 illustrates a first database 103 storing a collection of records 102 , each of the multiple records 102 being associated with a unique identifier 120 , which may comprise a UPC, lot number, or combination of UPC and lot number. Accordingly, a one-to-many mapping between the unique identifier 120 and multiple records 102 is maintained. [0114] The certification server 454 also has access to a second database 105 , which is shown to include product records 456 that include detailed information regarding agricultural products, guideline records 458 (e.g. organic certification guidelines, Marine Stewardship Council accreditation guidelines, EPA Clean Water Act standards, etc.), agricultural production system records 460 that include details regarding agricultural production systems 15 (e.g., such as those described with reference to FIG. 1 ), custodian records 462 that contain records regarding various custodians in a chain of custody, lot records 464 that may contain additional information regarding a lot of agricultural products, and quality records 466 (e.g., size, color, purity, brix level, harvest date, etc.). [0115] In summary, the certification server 454 receives raw data, or unprocessed records 102 , from the various submitters, and outputs a processed record 102 that is expanded to include further information derived from the above mentioned tables 456 - 468 of the database 105 and information that is generated by the certification server 454 itself. [0116] The certification server 454 includes a control module system 470 that is responsible for coordinating the functioning of the various components of the certification server 454 . These components include a certification tool 472 that is responsible for automatically generating a compliance result based on the automatic comparison of product data, embodied in a record 102 , with compliance requirements as specified in a particular guideline record 458 . In one embodiment, the certification tool 472 may functionally operate to certify a particular product, identified by a UPC and/or a lot number, as complying with certification guidelines, as described in a guidelines record 458 , for any one of multiple certification authorities. Merely for example, The Food. Alliance has issued a set of guidelines entitled “Commodity Specific Guidelines for Wine Grapes in the Pacific Northwest”, these guidelines specify cultural practices (e.g., cover crops, adjacent area management, stock selection, harvest and storage practices), crop nutrition guidelines (e.g., fertilizer applications and soil pH levels) insect/mite management guidelines, disease/nematodes management guidelines, and weed management guidelines that should be complied with in order to receive a wine grape certification from The Food Alliance. Similarly, the Conservation Agriculture Network has issued a banana standard entitled “Complete Standards for Banana Certification”, which specifies ecosystem conservation, wildlife conservation, fair treatment and good conditions for workers, community relations, agro-chemical management, waste management, water resource conservation, soil conservation and environmental planning and monitoring requirements that must be complied with in order to receive an appropriate certification from the Conservation Agriculture Network. Again, the compliance requirements for the above standards and guidelines may be embodied within one or more records within the guideline records 458 of the database 105 . The certification tool 472 operates automatically to compare agricultural product data, in the form of the records 102 , against the compliance requirements specified within such guidelines or standards, and to generate a compliance result based on this automatic comparison. The compliance result typically comprises a report 474 , which the certification server 454 may report to a user 451 . For example, the report 474 may be generated in real-time responsive to an inquiry from the user 451 . Alternatively, the report 474 may be generated once sufficient agricultural product data has been collected from the various submitters, and the report 474 may then be stored as part of the record 102 and accessed at any time. [0117] The certification server 454 also includes a report tool 475 that operates to generate custom reports (e.g., daily, seasonal or yearly pest management reports) based on the agricultural product data received from various submitters. Further details regarding the report in process will be provided below. [0118] An identification generator 476 operates to generate the unique identifier 120 which may be associated with multiple records within the database 103 of the system 50 . As described above, the unique identifier may be a UPC, a lot number, or the combination thereof (e.g., an encrypted identifier). [0119] A custody tool 478 operates to include further custodial information within a record 102 , as extracted from the custodian records 462 . [0120] A regulatory tool 480 operates substantially in the same way discussed above with respect to the certification tool 472 , but instead operates to generate a regulatory compliance certificate as a compliance result based on the comparison of the agricultural product data against regulatory compliance requirements as specified in one or more guideline records 458 . An accreditation tool 473 operates substantially in the same way discussed above. [0121] An interface 482 , that accesses communication parameters 484 , facilitates access to the database 105 . For example, the interface 482 may be implemented by a Database Management System (DBMS) so as to enable the control module system 470 to issue secure queries against the database 103 . Methodology—Creation of Compliance Result [0122] FIG. 14 is a flow chart illustrating a method 500 , according to an exemplary embodiment of the present invention, of automatically generating a compliance result based on the automated comparison of agricultural product data against compliance requirements in the form of certification requirements. While the method 500 is described below, as generating a certification record based on a comparison against certification guidelines, it will be appreciated that any compliance result may be generated using substantially the same methodology. For example, a compliance record (e.g., regulatory) or an accreditation record may be generated substantially in the same manner. [0123] The method 500 commences with the submission at block 502 from a submitter (e.g., custodian 48 , an automated data capture mechanism 450 or other submitter 452 ) of a record 102 , such as for example, the record illustrated in FIG. 5 . In addition to the information specified in FIG. 5 , the record 102 may also specify a particular product, particular production practices/processes 20 applied to that product, inputs used to produce/process the product 22 , biological process 24 that influenced the production/processing of that product, the duration of time 26 that took place to produce/process the product, resultant impacts 30 , and a guideline specifier that may be utilized to locate a guideline record 458 within the database 103 . To this end, a custodian, for example, may when submitting agricultural product data specify that the record is contributing towards a determination as to whether a particular agricultural product complies with certain organic standards criteria. In a further embodiment, a witness may authenticate some or all the data submitted to add an additional level of credibility. [0124] At block 504 , the certification server 454 receives the record 102 from the submitter and, at block 506 , the identification generator 476 adds an internal identifier 120 (or key) to the record 102 . Again, the internal identifier may comprise a UPC, a lot number, or a code derived from the UPC and/or the lot number. [0125] At block 508 , the control module system 470 of the certification server 454 stores the original received record 102 in combination with the identifier 120 within the database 103 . [0126] At block 510 , the certification tool 472 (or the regulatory tool 480 or accreditation tool 473 ) generates a compliance result in the exemplary form of a certification record (or regulatory compliance record or accreditation compliance record) by performing a comparison of compliance requirements against the captured agricultural product data. As described above, the compliance requirements for a specific certification record may be specified in a guideline record 458 . The creation of the certification record 510 may include generating a compliance report that provides metrics, derived from the agricultural data, against a number of factors specified by an certification/accreditation/regulatory authority. [0127] Further, the certification record 510 may indicate an affirmative compliance result or negative compliance result. The affirmative compliance result may comprise a standard certification, a government regulatory compliance approval, or an accreditation. [0128] At block 514 , the created certification record is then stored, either as an integral part of the product data record, or in a relational database as a distinct record that is keyed (or linked) to the agricultural product data record 102 . Methodology—User Product Information Retrieval [0129] FIG. 15 is a flow chart illustrating a method 520 , according to an exemplary embodiment of the present invention, of communicating agricultural product information to a user (e.g., a consumer, farmer or certification authority). [0130] The method 520 commences at block 522 with the input of a serial number (e.g., a UPC) by an inquiring user 451 to the agricultural management information system 50 . In one exemplary embodiment, the input of the serial number to the system 50 may be via a computer system 532 coupled via a network 180 to the agricultural management information system 50 , as is illustrated in FIG. 16A . In the exemplary embodiment shown in FIG. 16A , a product identifier in the form of a UPC embodied in a barcode 536 printed on a label 534 is inputted to the computer system 532 via a barcode reader 194 that performs a read operation of the relevant barcode 536 . [0131] FIG. 16A also illustrates that the agricultural management information system 50 may communicate a user interface 538 , via the network 180 , to the computer system 532 for display on a display device 540 that forms part of the computer system 532 . The user interface 538 may include a serial number input field 542 . The serial number may be inputted into the input field 542 manually, utilizing a keyboard 544 , or automatically utilizing the barcode reader 194 . [0132] The user interface 538 is also shown to present a menu of certification options 546 , each option 546 having an associated check box that may be utilized to prompt the user to identify certain certification standards, criteria or guidelines, merely by example. By selecting associated check boxes, a user is able to identify, for example, certain certification standards by which the user is interested. [0133] In one embodiment, the user interface 538 comprises a markup language document (e.g., a hypertext markup language (HTML) document) that is generated by a web server that forms part of the agricultural management information system 50 . The input by the user to the interface 538 is communicated, via the network 180 , back to the agricultural management information system 50 as a request for agricultural product information. [0134] FIG. 16B shows example labels 534 , each bearing a respective barcode 536 , as applied to an assortment of agricultural products. [0135] Further, while FIG. 16A illustrates a personal computer system 532 as being an input device, it will be appreciated that the request for agricultural product information may be inputted, by user 451 , into any of a number of network-connected devices for communication via the network 180 to the agricultural management information system 50 . For example, an appropriate interface to harvest information to be included in such a request may be presented on a PDA, a mobile telephone, a hand-held computer, a pager, or a radio-based communication device. While the UPC is also described in FIG. 16A should be entered via a keyboard 544 , or utilizing a barcode reader 194 , it will be appreciated that multiple other input mechanisms may be utilized to input the UPC. Specifically, an optical, radio, infrared, audio or video input mechanisms associated with a computing device may be utilized. [0136] Returning to the method 520 , illustrated in FIG. 15 , at block 524 , the user may optionally input a lot number for a particular agricultural product. The lot number may be entered in any one of the ways described above for the input of the serial number. [0137] At block 526 , the agricultural management information system 50 , having now received a serial number and/or a lot number, proceeds to locate records associated with the serial and/or lot numbers. To this end, reference is again made to FIG. 12 , which illustrates a hierarchy of records 102 and reports 408 associated with a specific UPC 402 and lot code 404 within the collection 400 being maintained within the database 103 of the agricultural management information system 50 . [0138] At block 528 , having identified the appropriate records 102 , the agricultural management information system 50 , and more specifically the certification tool 472 of the certification server 454 , proceeds to compare the identified records with certification criteria specified within an appropriate guideline record 458 . Similarly, in an alternative embodiment, at block 528 , the regulatory tool 480 may compare located records with regulatory criteria as specified within a guideline record 458 . In a further embodiment, at block 528 , the accreditation tool 473 may compare located records with accreditation criteria as specified within a guideline record 458 . Examples of certification criteria are provided in FIG. 15 . [0139] At block 530 , the results of the comparison operation performed at block 528 are reported to the user. In one exemplary embodiment, the comparison results may be reported in the form of a markup language document (e.g., a HTML document) that is generated by a web server of the agricultural management information system 50 , and communicated via a network 180 to a computer system 532 operated by the user. The certification results may, in one embodiment, simply comprise a list of standards (e.g., certification, regulatory, accreditation, etc.) with which the relevant agricultural product complies. This embodiment may be directed towards a consumer who is interested in only high-level information. In an alternative embodiment, more detailed information may be communicated as part of the comparison results. For example, the certification tool 472 may provide a listing of criteria, with a metric indicated for each of the relevant criteria. The metric may comprise a certification status (e.g., pass, fail) or a relative compliance label (e.g., a grade, percentage value, rating relative to a standard, grade in terms such as poor, fair, good or super, or a statistically derived confidence interval). The resolution of information displayed with respect to a standard, and the criteria that define that standard, are customized to accommodate the requirements of a particular user. [0140] While the comparison of the records with the criteria, at block 528 , is described above as being performed responsive to the receipt of a request for agricultural product information, it will be appreciated that the comparison operation may be performed off-line, prior to the receipt of any request, and the results of the comparison stored as a report 408 within the collection 400 for later retrieval responsive to a request. [0141] The method 520 discussed with reference to FIG. 15 provides an example of reporting a level of compliance of an agricultural product, based on agricultural product data collected along the chain of custody, with a standard (e.g., a certification standard). It will nonetheless be appreciated that the information embodied in the records 102 , as stored by the database of the agricultural management information system 50 , is also very useful to a farmer (or producer, processor, etc.) for the purposes of evaluating performance of and reviewing of, an agricultural production system 15 over time (e.g., a season or one or more years as described in FIG. 2 ). To this end, a user may, in a manner similarly described with reference to FIG. 15 , input information pertaining to an agricultural production system (e.g., a unit of production identifier), responsive to which the report tool 474 of the certification server 454 locates records associated with the relevant agricultural production system 15 (e.g., a field of land). In addition to an identifier for an agricultural product system 15 , the request from the farmer may include a specific characteristic in which the user is interested. For example, the user may be interested in the number of pests (e.g., leafhoppers) observed at a particular trap within a particular season, or over a number of years. In this case, the report tool 475 is able to extract the appropriate data from the located records, and generate textual or graphic reports. To this end, FIG. 17A shows exemplary seasonal reports 600 and historic reports 602 of the number of leafhoppers identified within a particular trap both seasonally and over a number of years. Additionally, the report tool 475 generates graphs to provide a visual representation of observed or measured values for a particular characteristic. [0142] FIG. 17B provides a further example of a weekly pest management monitoring report 620 that may be generated by the report tool 474 responsive to a request from a user 451 . Once again, the information displayed in the report 620 is extracted from the connection 400 of records 102 , responsive to a user inquiry. [0143] Individual reports may also rank, rate, and/or provide descriptive and inferential statistics so as to provide a meaningful comparative view of the captured agricultural product data. Such reports go beyond a mere “yes/no” compliance, and enable a user to differentiate between custodians of an agricultural product based on a selected one, or multiple, metrics (e.g., environmental conditions, quality, time to market, etc.). A user 451 (e.g., a consumer) is then able to perform a comparative selection based on one or more metrics. For example, a consumer may request information regarding “good”, “better” or “best” based on one or more metrics, or may elect to receive information regarding the top ten-percent of environmentally sound products, merely for example. [0144] Similarly, at the end of a production cycle (e.g., a season) or a predefined time period (e.g., every six months, every twelve months, etc.), a user 451 (e.g., a farmer or other producer) may be presented with a summary report (or aggregation) of all compliance reports for the predetermined time period. Such a summary report may be utilized by the producer as a benchmark for future production cycles, to calculate end-of-cycle balances or for multiple other purposes. [0145] To this end, FIG. 17C provides an example of an aggregate report 622 that graphically illustrates water use efficiency per year measured in acre/feet for a group of winegrape growers. In this example, a rating system is based on the most efficient growers determined by the top ten percent of growers along a water use efficiency scale. In one embodiment, the report 622 may be hyperlinked so as to allow a user conveniently to “click through” the illustrated graph to identify the names of the growers in, for example, the top ten-percent for water use efficiency. [0146] FIG. 17D illustrates a further exemplary report in the form of a pesticide use report 624 that provides a graphic depiction of pesticide use per year measured by pounds applied per acre. In this example, a rating system is based on a five-category scale that ranges from “best” 626 to “poor” 628 , with equal intervals defined at 20 lbs. per year. Accordingly, in contrast with the report 622 discussed with reference to FIG. 17 which provides a percentage-based rating, the report 624 illustrated in FIG. 17D provides discrete, descriptive classifications or ratings of growers. Again, the report 624 may provide a “click through” functionality so as to enable a user 451 conveniently to identify growers falling within each of the respective categories. [0147] Further, a request to user 451 may require that a sample population be limited according to specified criteria. For example, the user 451 may specify that only a specific type of custodian (e.g., a grower, processor, transporter) be considered within a specific biologically meaningful unit (e.g., ecosystem, watershed, biological community, habitat, species population range, etc.), politically meaningful unit (e.g. country, state, region, county, city, town, village, etc.), and/or geographic region (e.g., section, town, range, etc.). Furthermore, the user 451 may request that the report only consider growers involved in one or more certification programs (e.g., organic, sustainable, integrated pest management, genetically-modified organism free, etc.). While irrigation water and pesticide use have been provided as examples of metrics of interest above, it will be appreciated that any one of a predetermined set of metrics may be selected. For example, user 451 may wish to view a comparative rating of a custodian based on energy use, impacts on water quality, impacts on air quality, level of biodiversity found in and around the production unit, time to market, ripeness, etc. [0148] The reports discussed above may, in one embodiment, be generated as markup language documents that are communicated from the agricultural management information system 50 , via the network 180 , to a computer system 532 . [0149] Thus, a method and system to automatically certify an agricultural product, have been described. Although the present invention has been described with reference to specific exemplary embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Various embodiments of the present disclosure include methods and apparatus for recording and reporting video corresponding to production of an agricultural product. In an example embodiment, an apparatus comprises a hand-held device including a display and one or more input devices to sense product identification indicia associated with or affixed to a food product that is grown or raised in an agricultural operation. The hand-held device includes at least one processor to determine a machine-readable identification code from the product identification indicia; send the identification code to at least one remote server; receive, from the at least one remote server, video data that is associated with the product. The video data is reproducible on a video display apparatus to produce a human-viewable video showing at least one aspect of the production of the food product.

This is a divisional application of U.S. Application Ser. No. 07/565,306 filed Aug. 9, 1990. BACKGROUND OF THE INVENTION Excessive excitation by neurotransmitters can cause the degeneration and death of neurons. It is believed that this degeneration is in part mediated by the excitotoxic actions of glutamate and aspartate at the N-methyl-D-aspartate (NMDA) receptor. This excitotoxic action is responsible for the loss of neurons in cerebrovascular disorders such as: cerebral ischemia or cerebral infraction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, perinatal asphyxia, cerebral trauma and anoxia (such as from drowning and pulmonary surgery). There are no specific therapies for these neurodegenerative diseases, however, compounds which act specifically as antagonists of the NMDA receptor complex, either competitively or noncompetitively, offer a novel therapeutic approach to these disorders: R. Schwarcz and B. Meldrum, The Lancet 140 (1985); B. Meldrum in "Neurotoxins and Their Pharmacological Implications" edited by P. Jenner, Raven Press, New York (1987); D. W. Choi, Neuron 1:623 (1988). Confirmation of the protective effects of noncompetitve NMDA antagonists in various pharmacological models of neurodegenerative disorders have appeared in the literature: J. W. McDonald, F. S. Silverstein, and M. V. Johnston, Eur. J. Pharmocol. 140:359 (1987); R. Gill, A. C. Foster, and G. N. Woodruff, J. Neurosci. 7:3343 (1987); S. M. Rothman, J. H. Thurston, R. E. Hauhart, G. D. Clark, and J. S. Soloman, Neurosci. 21:673 (1987); M. P. Goldbert, P-C. Pham, and D. W. Choi, Neurosci. Lett. 80:11 (1987); L. F. Copeland, P. A. Boxer, and F. W. Marcoux, Soc. Neurosci. Abstr. 14 (part 1):420 (1988); J. A. Kemp, A. C. Foster, R. Gill, and G. N. Woodruff, TIPS 8:414 (1987); R. Gill, A. C. Foster, and G. N. Woodruff, J. Neurosci. 25:847 (1988); C. K. Park, D. G. Nehls, D. I. Graham, G. M. Teasdale, and J. M. McCulloch, Ann. Neurol. 24:543 (1988); G. K. Steinburg, C. P. George, R. DeLaPlaz, D. K. Shibata, and T. Gross, Stroke 19:1112 (1988); J. F. Church, S. Zeman, and D. Lodge, Anesthesiology 69:702 (1988). The compounds of the present invention are useful in the treatment of neurodegenerative disorders including cerebrovascular disorders. Such disorders include but are not limited to cerebral ischemia or cerebral infarction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, perinatal asphyxia, cerebral trauma and anoxia such as from drowning and/or pulmonary surgery. Other treatments are for schizophrenia, epilepsy, spasticity, neurodegenerative disorders such as Alzheimer's disease or Huntington's disease, Olivo-pontocerebellar atrophy, spinal cord injury, and poisoning by exogenous NMDA poisons (e.g., some forms of lathyrism). Further uses are as analgesics and anesthetics, particularly for use in surgical procedures where a finite risk of cerebrovascular damage exists. SUMMARY OF THE INVENTION The present invention concerns compounds of the formula I ##STR1## or a pharmaceutically acceptable acid addition salt thereof wherein R 1 , R 2 , R 3 , m, and n are as described herein below. The present invention also includes a pharmaceutical composition comprising a therapeutically effective amount of a compound of formula I together with a pharmaceutically acceptable carrier. The present invention also includes a method for treating cerebrovascular disorders which comprises administering to a patient in need thereof the above pharmaceutical composition in unit dosage form. The present invention also includes a method of treating disorders responsive to the blockade of glutamic and aspartic acid receptors in a patient comprising administering a therapeutically effective amount of the above composition. The invention also includes a method for treating cerebral ischemia, cerebral infarction, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, cerebral trauma, schizophrenia, epilepsy, neurodegenerative disorders, Alzheimer's disease, or Huntington's disease comprising administering to a patient in need thereof a therapeutically effective amount of the above composition. The invention also includes a method for treating stroke in patients in need thereof which comprises administering to a patient in need thereof a therapeutically effective amount of the above composition. The invention also includes using as an anesthetic the above composition in surgical operations where a risk of cerebrovascular damage exists. The invention further includes processes for the preparation of compounds of formula I. The invention still further includes novel intermediates useful in the processes. DETAILED DESCRIPTION The present invention concerns compounds of the formula ##STR2## or a pharmaceutically acceptable acid addition salt thereof wherein: R 1 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, arylloweralkyl, cyclopropylloweralkyl, or a pharmaceutically acceptable labile group; R 2 and R 3 are each independently hydrogen, lower alkyl, hydroxy, lower alkoxy, halogen, amino, monoloweralkylamino, diloweralkylamino; m is an integer of from 0 to 2; and n is an integer of from 2 to 4. Preferred compounds of the instant invention are those of formula I wherein: R 1 is hydrogen, lower alkyl, lower alkenyl, cyclopropylmethyl or arylloweralkyl; R 2 and R 3 are independently hydrogen, lower alkyl, hydroxy, or lower alkoxy; m is an integer of 0 or 1; n is 2 or 3; and indicates the ring is cis relative to its attachment at to the molecule. More preferred compounds of the instant invention are those of formula I wherein: R 1 is hydrogen, lower alkyl, cyclopropylmethyl, or arylloweralkyl; R 2 and R 3 are independently hydrogen, hydroxy, or lower alkoxy; m is an integer 0 or 1; and n is an integer 2 or 3. Still more preferred are compounds of formula I wherein: R 1 is hydrogen, methyl, ethyl, propyl, allyl, cyclopropylmethyl, or benzyl; R 2 and R 3 are each independently hydrogen, methoxy, or hydroxy; m is the integer 0 or 1; and n is the integer 2 or 3. Other more preferred compounds of the instant invention include: (+), (-), or (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-7-methoxy-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-) or (±)-2,3-Dihydro-7-methoxy-1-ethyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3,4,5-tetrahydro-1-(2-propenyl)-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indol-8-ol, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indol-8-ol, (+), (-), or (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol, (+), (-), or (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol, (+) (-), or (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-) , or (±)-1,2,3,4,-Tetrahydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-1-methyl-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-), or (±)-1,2,3,4,-Tetrahydro-8-methoxy-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinolin-9-ol, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinolin-9-ol, (+), (-), or (±)-1,2,3,4-Tetrahydro-1a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol, and (+), (-), or (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol. Most preferred compounds of the instant invention are: (+), (-), or (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-ethyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-propyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-(cyclopropylmethyl)-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-phenylmethyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-1-methyl-3a,9b-butano-1H-benz[g]indole, and (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-1-ethyl-3a,9b-butano-1H-benz[g]indole. Compounds of the instant invention include solvates, hydrates, and pharmaceutically acceptable salts of compounds of formula I above. The compounds of the present invention contain asymmetric carbon atoms. The instant invention includes the individual enantiomers, which may be prepared or isolated by methods known in the art. Any resulting racemates can be resolved into the optical antipodes by known methods, for example by separation of the diastereomeric salts thereof, with an optically active acid, and liberating the optically active amine compound by treatment with a base. Racemic compounds of the instant invention can thus be resolved into their optical antipodes e.g., by fractional crystallization of d- or 1- (tartarates, mandelates, or camphorsulfonate) salts. The compounds of the instant invention may also be resolved into the optical antipodes by the formation of diastereomeric carbamates by reacting the compounds of the instant invention with an optically active chloroformate, for example (-)-menthyl chloroformate, or by the formation of a diastereomeric amide by reacting the compounds of the instant invention with an optically active activated carboxy acid such as that derived from (+) or (-) phenylalanine, (+) or (-) phenylglycine, (-)-camphanic acid or the like. Additional methods for resolving optical isomers, known to those skilled in the art may be used, for example those discussed by J. Jaques, A. Collet, and S. Wilen in "Enantiomers, Racemates and Resolutions", John Wiley and Sons, New York (1981). The term lower in connection with organic groups, radical or compounds includes up to and including seven members, preferably up to and including four and most preferably one, two, or three carbon atoms except as otherwise specifically described. Lower alkyl means a straight or branched chain of from one to four carbon atoms including but not limited to methyl, ethyl, propyl, isopropyl, and butyl. Lower alkenyl means a group from one to four carbon atoms, for example, but not limited to ethylene, 1,2- or 2,3-propylene, 1,2- 2,3-, or 3,4-butylene. Preferred is 2,3-propylene. Lower alkynyl means a group from one to four carbon atoms, for example, but not limited to ethynyl, 2,3-propynyl, 2,3-, or 3,4-butynyl; propynyl is the preferred group. Cyclopropylloweralkyl means cyclopropyl-C 1-4 -alkyl, meaning for example, cyclopropylmethyl, 2-(cyclopropyl)ethyl, 3-(cyclopropyl)propyl; cyclopropylmethyl is the preferred group. Lower alkoxy means a group of from one to four carbon atoms, for example, but not limited to methoxy, ethoxy, propoxy; methoxy is the preferred group. Halogen is fluorine, chlorine, bromine, or iodine; fluorine, chlorine, and bromine are the preferred groups. Arylloweralkyl means aryl-C 1-4 -alkyl, meaning for example, benzyl, 2-phenylethyl, 3-phenylpropyl; preferred group is benzyl. The aryl groups may be substituted, for example, by lower alkyl, lower alkoxy, hydroxy, and halogen. Monoloweralkylamino means a group containing from one to four carbon atoms, for example, but not limited to methylamino, ethylamino, n- or i-(propylamino or butylamino). Diloweralkylamino means a group containing from one to four carbon atoms in each lower alkyl group, for example, but not limited to dimethylamino, diethylamino, di-(n-propyl)-amino, di-(n-butyl)-amino, or may represent a fused ring, for example piperidine. Physiologically labile group includes but is not limited to such derivatives described by; I. H. Pitman in Med. Chem. Rev. 2:189 (1981); J. Alexander, R. Cargill, S. R. Michelson and H. Schwam in J. Med. Chem. 31:318 (1988); V. H. Naringrekar and V. J. Stella in European Patent Application 214,009-A2 and include certain amides, such as amides of amino acids, for example glycine, or serine, enaminone derivatives and (acyloxy)alkylcarbamates. Well-known protecting groups and their introduction and removal are described, for example, in J. F. W. McOmie, Protective Groups in Organic Chemistry, Plenum Press, London, New York (1973), and T. W. Greene, Protective Groups in Organic Synthesis, Wiley, New York (1981). Salts of the compounds of the invention are preferably pharmaceutically acceptable salts. The compounds of the invention are basic amines from which acid addition salts of pharmaceutically acceptable inorganic or organic acids such as strong mineral acids, for example, hydrohalic, e.g., hydrochloric or hydrobromic acid; sulfuric, phosphoric or nitric acid; aliphatic or aromatic carboxylic or sulfonic acids, e.g., acetic, propionic, succinic, glycolic, lactic, malic, tartaric, gluconic, citric, ascorbic, maleic, fumaric, pyruvic, pamoic, nicotinic, methanesulfonic, ethanesulfonic, hydroxyethanesulfonic, benzenesulfonic, p-toluenesulfonic, or napthlenesulfonic acid can be prepared. For isolation or purification purposes, salts may be obtained which might not be useful for pharmaceutical purposes. Pharmaceutically acceptable salts useful for therapeutic purposes are preferred. The present invention also includes processes for making the compounds of formula I above. One process for the preparation of compounds of formula I is illustrated in Scheme A below. ##STR3## Step (1) The compound of formula II wherein m is 0 or 1 ##STR4## and R 2 and R 3 are as previously defined are treated with 1,4-dibromobutane under conditions described in Bull. Soc. Chim. France 346 (1957) to give the compounds of the formula III. ##STR5## Step (2) The compounds of the formula III are treated with lithioacetonitrile, in a solvent such as ether, tetrahydrofuran, or the like, at a temperature between -78° C. and 20° C. to afford the compounds of the formula IV. ##STR6## Step (3) The compounds of the formula IV are hydrogenated in the presence of a catalyst such as Raney Nickel, or the like, in a solvent such as methanol or ethanol containing ammonia, under a hydrogen atmosphere to give the compounds of the formula V wherein n is 2. ##STR7## Step (4) Alternatively, the compounds of the formula III are treated with a compound of the formula VI ##STR8## under conditions described by Evans et al in J. Amer. Chem Soc. 371, (1979) or by other methods known to those skilled in the art, such as those described in Tetrahedron 205, (1983) to give the compounds of the formula VII. ##STR9## Step (5) The compounds of the formula VII are treated with ammonia in a solvent such as toluene, tetrahydrofuran, or the like to give the compounds of the formula VIII. ##STR10## Step (6) The compounds of the formula VIII are reduced using lithium aluminum hydride, diborane, or the like, in a solvent such as ether, tetrahydrofuran, or the like to give the compounds of the formula V wherein n is 3. Step (7) The compounds of the formula V are treated with methyl chloroformate, ethyl chloroformate, 2,2,2-trichloroethyl chloroformate or an optically active chloroformate, for example (-)-menthyl chloroformate, (-)-α-methylbenzyl chloroformate or the like, in the presence of a trialkylamine such as triethylamine, tributylamine, diisopropylethylamine or the like, in a solvent such as dichloromethane, chloroform, or the like, to give the compounds of the formula IX wherein R 5 is methyl, ethyl, 2,2,2-trichloroethyl, (-)-menthol, (-)-α-methylbenzyl, or other acid stable protecting group. ##STR11## Step (8) The compounds of the formula IX are treated with acetic acid, formic acid, triflouroacetic acid, sulfuric acid or the like or combinations thereof, preferably combinations of acetic acid and sulfuric acid to give the compounds of the formula X ##STR12## Step (9) The compounds of the formula X are treated to remove the carbamate functionalitity using methods known to those skilled in the art for example wherein R 5 is 2,2,2-trichloroethyl the compounds are treated with zinc dust in methanol, ethanol or the like, in the presence of acetic acid, to afford the compounds of the formula I wherein n is 2 or 3, m is 0 or 1, R 1 is hydrogen and R 2 and R 3 are as previously defined. Step (10) The compounds of the formula I wherein R 1 is hydrogen are treated with an aldehyde such as formaldehyde, acetaldehyde, benzaldehyde or the like or with a ketone such as acetone, acetophenone, or the like, in the presence of a reducing agent such as sodium cyanoborohydride or the like, in a solvent such as methanol, ethanol or the like to give the compounds of the formula I wherein n is 2 or 3, m is 0 or 1, R 1 is as previously defined excepting hydrogen, and R 2 and R 3 are as previously defined. Step (11) Alternatively the compounds of the formula X are reduced in the presence of lithium aluminum hydride, diborane or the like, in a solvent such as ether, tetrahydrofuran or the like, to afford the compound of the formula I wherein R 1 is methyl. Novel intermediates useful in the preparation of compounds of formula I are: Spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one, 7,-methoxy-spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile, (+), (-), or (±)-3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxy-6-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile, (+), (-), or (±)-2'-(2-aminoethyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2H)-napthalen]-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-2',3',-dihydrospiro[cyclopentane-1,1'-[1H]inden-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden-2'-ol, Ethyl (+), (-), or (±)-[2-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate, (+), (-, ) or (±)-2,2,2-Trichloroethyl-[2-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-[2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate, Ethyl (+), (-), or (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3,4,5-tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3-dihydro-1H,4H-3a,8b-butanoindeno-[1,2-b]pyrrole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3-dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate, (+), (-), or (±)-3',3",4',4"Tetrahydrodispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one, (+), (-), or (±)-3',3",4',4"-Tetrahydro-7'-methoxydispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one, (+), (-), or (±)-3",4"-Dihydrodispiro-[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)furan]-5"-one, (+), (-), or (±)-3",4"-Dihydro-6'-methoxydispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)furan]-5"-one, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxy-7'methoxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide, (+), (-), or (±)-2',3',-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide, (+), (-), or (±)-2'-(3-aminopropyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol, (+), (-), or (±)-2'-(3-aminopropyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol, (+), (-), or (±)-2'-(3-aminopropyl)-2',3'-dihydrospiro[cyclopentane-1,1'-[1H]inden]-2'-ol , (+), (-), or (±)-2'-(3-aminopropyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-ol, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)-propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4,5,6-tetrahydro-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4,5,6-tetrahydro-9-methoxy-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4-dihydro4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate, and (+), (-), or (±)-2,2,2-Trichloroethyl-3,4-dihydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate. The compounds of the instant invention exhibit valuable pharmacological properties by selectively blocking the N-methyl-D-aspartate sensitive excitatory amino acid receptors in mammals. The compounds are thus useful for treating diseases responsive to excitatory amino acid blockade in mammals. The effects are demonstrable in in vitro tests or in vivo animal tests using mammals or tissues or enzyme preparations thereof, e.g., mice, rats, or monkeys. The compounds are administered enterally or parenterally, for example, orally, transdermally, subcutaneously, intravenously, or intraperitoneally. Forms include but are not limited to gelatin capsules, or aqueous suspensions or solutions. The applied in vivo dosage may range between about 0.01 to 100 mg/kg, preferably between about 0.05 and 50 mg/kg, most preferably between about 0.1 and 10 mg/kg. The ability of the compounds of the instant invention to interact with phencyclidine (PCP) receptors which represents a noncompetitive NMDA antagonist binding site, is shown by Examples 23 and 27 which bind with an affinity of less than 10 μM. Tritiated 1-[1-(2-thienyl)cyclohexyl]pipiridine (TCP) binding, designated RBS1, was carried out essentially as described in J. Pharmacol. Exp. Ther. 238, 739 (1986). For medical use, the amount required of a compound of formula I or pharmacologically acceptable salt thereof--(hereinafter referred to as the active ingredient) to achieve a therapeutic effect will, of course, vary both with the particular compound, the route of administration and the mammal under treatment and the particular disorder or disease concerned. A suitable systemic dose of a compound of formula I or pharmacologically acceptable salt thereof for a mammal suffering from, or likely to suffer from any condition as described herein before is in the range 0.01 to 100 mg of base per kilogram body weight, the most preferred dosage being 0.05 to 50 mg/kg of mammal body weight. It is understood that the ordinarily skilled physician or veterinarian will readily determine and prescribe the effective amount of the compound for prophylactic or therapeutic treatment of the condition for which treatment is administered. In so proceeding, the physician or veterinarian could employ an intravenous bolus followed by intravenous infusion and repeated administrations, parenterally or orally, as considered appropriate. While it is possible for an active ingredient to be administered alone, it is preferable to present it as a formulation. Formulations of the present invention suitable for oral administration may be in the form of discrete units such as capsules, cachets, tablets, or lozenges, each containing a predetermined amount of the active ingredient; in the form of a powder or granules; in the form of a solution or a suspension in an aqueous liquid or nonaqueous liquid; or in the form of an oil-in-water emulsion or a water-in-oil emulsion. The active ingredient may also be in the form of a bolus, electuary, or paste. A tablet may be made by compressing or molding the active ingredient optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active, or dispersing agent. Molded tablets may be made by molding, in a suitable machine, a mixture of the powdered active ingredient and a suitable carrier moistened with an inert liquid diluent. Formulations suitable for parenteral administration conveniently comprise a sterile aqueous preparation of the active ingredient which is preferable isotonic with the blood of the recipient. Formulations suitable for nasal or buccal administration (such as self-propelling powder dispensing formulations described hereinafter), may comprise 0.1 to 20% w/w, for example, 2% w/w of active ingredient. The formulations, for human medical use, of the present invention comprise an active ingredient in association with a pharmaceuticaly acceptable carrier therefor and optionally other therapeutic ingredient(s). The carrier(s) must be `acceptable` in the sense of being compatible with the other ingredients of the formulations and not deleterious to the recipient thereof. So the pharmacologically active compounds of the invention are useful in the manufacture of pharmaceutical compositions comprising an effective amount thereof in conjunction or admixture with excipients or carriers suitable for either enteral or parenteral application. Preferred are tablets and gelatin capsules comprising the active ingredient together with a) diluents, e.g. lactose, dextrose, sucrose, mannitol, sorbitol, cellulose, and/or glycine; b) lubricants, e.g. silica, talcum, stearic acid, its magnesium or calcium salt, and/or polyethyleneglycol; for tablets also c) binders e.g. magnesium aluminum silicate, starch paste, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose and/or polyvinylpyrrolidone; if desired d) disintegrants, e.g. starches, agar, alginic acid, or its sodium salt, or effervescent mixtures; and/or e) absorbents, colorants, flavors, and sweeteners. Injectable compositions are preferably aqueous isotonic solutions or suspensions, and suppositories are advantageously prepared from fatty emulsions, or suspensions. Said compositions may be sterilized and/or contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents, solution promoters, salts for regulating the osmotic pressure, and/or buffers. In addition, they may also contain other therapeutically valuable substances. Said compositions are prepared according to conventional mixing, granulating, or coating methods, respectively, and contain about 0.1 to 75%, preferably about 1 to 50%, of the active ingredient. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well-known in the art of pharmacy. All methods include the step of bringing the active ingredient into association with the carrier which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing the active ingredient into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired formulation. The following examples are illustrative of the present invention but are not intended to limit it in any way. EXAMPLE 1 ##STR13## 3',4'-Dihydrospiro[cyclopentane-1,1'(2'H)-napthlen]-2'-one A suspension of KOt-Bu (76.3 g, 0.68 mol) in 500 mL of xylene was treated dropwise with 2-tetralone (50 g, 0.34 mol). The resulting solution was treated dropwise with 1,4-dibromobutane (74.0 g, 0.34 mol) (exothermic reaction). The resulting suspension was heated to reflux for 18h. The reaction mixture was treated with water (200 mL) and the organic phase was collected. The aqueous phase was extracted with ethyl acetate (2×200 mL) and the combined organic extracts were dried (MgSO 4 ), filtered and concentrated. Distillation of the residue provided the product (65.6 g, 96%) as a colorless liquid. EXAMPLE 2 ##STR14## 3',4'-Dihydro-7'-methoxyspiro-8 cyclopentane-1,1'(2'H)-napthlen]-2'-one In a manner similar to that described in Example 1, 7-methoxy-2-tetralone (20.0 g, 0.113 mol) was converted to the title compound (10.3 g, 40%) as a colorless oil. EXAMPLE 3 ##STR15## Spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one In a manner similar to that described in Example 1, 2-indanone is converted to the title compound. EXAMPLE 4 ##STR16## 6'-Methoxy-spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one In a manner similar to that described in Example 1, 5-methoxy-2-indanone is converted to the title compound. EXAMPLE 5 ##STR17## (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile A solution of acetonitrile (1.1 g, 27.5 mmol) in 100 mL of anhydrous tetrahydrofuran (THF) was cooled to -78° C. and treated with lithium diisopropylamide (18 mL of a 1.5 M solution in tetrahydrofuran). The resulting suspension was stirred at -78° C. for 30 minutes and treated dropwise with a solution of the product from Example 1 (5.0 g, 24.9 mmol) in 10 mL of anhydrous THF. The resulting solution was warmed to room temperature and saturated aq. NH 4 Cl solution (15 mL) was added. The organic phase was collected and the aqueous phase was extracted with ether (3×50 mL). The combined organic phases were dried (MgSO 4 , filtered and concentrated. The solid which formed was suspended in diisopropyl ether and collected by suction filtration. The material was dried under vacuum to give the title compound (4.14 g, 69%) as a white solid mp 165°-166° C. Anal. (C 16 H 19 NO) Calc'd: C, 79.63; H, 7.94; N, 5.80 Found: C, 79.72; H, 7.86; N, 5.81 EXAMPLE 6 ##STR18## (±)-3',4'-Dihydro-2, hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 2 (10.0 g, 43.4 mmol) was converted to the title compound (4.33 g, 37%) as a tan solid mp 126°-127° C. Anal. (C 17 H 21 NO 2 ) Calc'd C, 75.25; H, 7.80; N, 5.16 Found: C, 75.36; H, 7.67; N, 4.94 EXAMPLE 7 ##STR19## (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 3 is converted to the title compound. EXAMPLE 8 ##STR20## (±)-2',3'-Dihydro-2'-hydroxy-6-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 4 is converted to the title compound. EXAMPLE 9 ##STR21## (±)-2'-(2-Aminoethyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)-napthalen]-2'-ol A solution of the product from Example 5 (2.50 g, 10.3 mmol) in 100 mL of methanolic ammonia was hydrogenated over Raney nickel (2.0 g) at 52 psi for 7.5 hours. The reaction mixture was filtered to remove the catalyst and the filtrate concentrated to give the title compound (2.59 g, quantitative) as a pale green solid mp 107°-109° C. Anal. (C 16 H 23 NO) Calc'd: C, 79.63; H, 7.94; N, 5.81 Found: C, 79.37; H, 8.02; N, 5.59 EXAMPLE 10 ##STR22## (±)-2'-(2-Aminoethyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1(2'H)-napthalen]-2'-ol In a manner similar to that described for Example 9, the product of Example 6 (4.85 g, 17.9 mmol) was hydrogenated to give the title compound (4.86 g, 99%) as a pale green solid. Anal. (C 17 H 25 NO 2 ) Calc'd: C, 74.14; H, 9.15; N, 5.08 Found C, 73.40; H, 9.19; N, 5.04 EXAMPLE 11 ##STR23## (±)-2'-(2-Aminoethyl)-2',3'-dihydrospiro[cyclopentane-1,1'-[1H]inden-2'-ol In a manner similar to that described for Example 9, the product of Example 7 is hydrogenated to give the title compound. EXAMPLE 12 ##STR24## (±)-2'-(2-Aminoethyl)-2',3'-dihydro-6'-methoxyspiro-[cyclopentane-1,1'-[1H]inden-2'-ol In a manner similar to that described for Example 9, the product of Example 8 is hydrogenated to give the title compound. EXAMPLE 13 ##STR25## Ethyl (±)-[2-(3',4'-dihydro-2'-hydroxyspiro-[cyclopentane-1,1'(2'H)-napthalen]-2'-yl)ethyl]-carbamate A solution of the product from Example 9 (1.05 g, 4.28 mmol) and triethylamine (0.44 g, 4.35 mmol) in 10 mL of CH 2 Cl 2 was cooled to 0° C. and ethyl chloroformate (0.47 g, 4.33 mmol) in 5 mL CH 2 Cl 2 was added dropwise. The reaction was warmed to room temperature and washed with water. The aqueous phase was extracted with CH 2 Cl 2 (3×20 mL) and the combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 1:1 heptane/ethyl acetate) to give the title compound (1.33 g, 98%) as an oil. EXAMPLE 14 ##STR26## 2,2,2-Trichloroethyl (±)-[2-(3',4'-dihydro-2'-hydroxyspiro-8 cyclopentane-1,1'(2'H)-naphthalen]-2'yl)ethyl]carbamate A solution of the product from Example 9 (0.88 g, 3.59 mmol) and triethylamine (0.40 g, 3.78 mmol) in 10 mL of CH 2 Cl 2 was cooled to 0° C. and treated dropwise with 2,2,2-trichloroethylchloroformate (0.80 g, 3.78 mmol) in 2 mL CH 2 Cl 2 . The resulting solution was stirred at 0° C. for 30 minutes and warmed to room temperature. The reaction mixture was washed with saturated aq. NaHCO 3 solution (10 mL). The aqueous phase was extracted with CH 2 Cl 2 (10 mL). The combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 10:1 heptane/ethyl acetate) to give the title compound (1.18 g, 78%) as a viscous oil. EXAMPLE 15 ##STR27## 2,2,2-Trichloroethyl (±)-[2-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 10 (4.66 g, 16.9 mmol) is converted to the title compound (6.81 g, as a foamy white solid. EXAMPLE 16 ##STR28## 2,2,2-Trichloroethyl (±)-[2-[2',3'-dihydro-2'-hydroxy-spiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 11 is converted to the title compound. EXAMPLE 17 ##STR29## 2,2,2-Trichloroethyl (±)-[2-[2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 12 is converted to the title compound. EXAMPLE 18 ##STR30## Ethyl (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate A solution of the product from Example 13 (1.68 g, 5.29 mmol) in 15 mL of 3:1 acetic acid/concentrated sulfuric acid (v/v) was stirred at room temperature for 18 hours. The reaction mixture was poured into water (50 mL) and the resulting mixture was extracted with CH 2 Cl 2 (4×30 mL). The combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was dissolved in CH 2 Cl 2 (100 mL and washed with saturated aq. bicarbonate solution (30 mL). The organic phase was dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 9:1 heptane/ethyl acetate) to give the title compound (0.94 g, 59%) as a white solid mp 67°-69° C. Anal. (C 19 H 25 NO 2 ) Calc'd: C, 76 22; H, 8.42; N, 4.68 Found: C, 75.99; H, 8.38; N, 4.41 EXAMPLE 19 ##STR31## 2,2,2-Trichloroethyl (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 14 (0.98 g, 2.33 mmol) was converted to the title compound (0.71 g, 76%) as an oil. EXAMPLE 20 ##STR32## 2,2,2-Trichloroethyl (±)-2,3,4,5-tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 15 (5.16 g, 11.4 mmol) was converted to the title compound (4.18 g, 84%) as an oil. EXAMPLE 21 ##STR33## 2,2,2-Trichloroethyl (±)-2,3-dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 16 is converted to the title compound. EXAMPLE 22 ##STR34## 2,2,2-Trichloroethyl (±)-2,3-dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 17 is converted to the title compound. EXAMPLE 23 ##STR35## (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indole hydrochloride A solution of the product from Example 19 (0.70 g, 1.74 mmol) in 20 mL of methanol and 0.5 mL acetic acid was treated with zinc dust (1.58 g, 320 mesh) and the resulting suspension stirred at room temperature for three hours. The reaction mixture was filtered and the filtrate concentrated. The residue was dissolved in ether (30 mL) and extracted with aqueous 1N HCl (3×15 mL). The combined acid extracts are made basic (pH=11) with potassium carbonate and the resulting aqueous solution was extracted with CH 2 Cl 2 (5×15 mL). The combined organic extracts were dried (Na 2 SO 4 , filtered and concentrated. The residue (0.30 g) was converted to its HCl salt by dissolution in ether and treatment with a saturated solution of HCl (gas) in ether. The solid which formed was collected by filtration and dried under vacuum (100° C.) to give the title compound (0.25 g, 54%) as a white solid mp >270° C. Anal (C 16 H 19 N.HCl) Calc'd: C, 72.85; H, 8.40; N, 5.31; Cl, 13.44 Found: C, 72.66; H, 8.38, N, 4.98; Cl, 13.83 EXAMPLE 24 ##STR36## (±)-2,3,4,5-Tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole In a manner similar to that described in Example 23, the product of Example 20 (3.76 g, 8.67 mmol) was converted to the title compound (1.47 g, 70%) as an oil. An analytical sample was prepared by crystallization of the fumarate salt from acetaone which gave a white solid mp 203°-204° C. Anal. (C 17 H 23 NO.C 4 H 4 O 4 ) Calc'd: C, 67.54; H, 7.29; N, 3.75 Found: C, 67.55; H, 7.18; N, 3.61 EXAMPLE 25 ##STR37## (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole In a manner similar to that described in Example 23, the product of Example 21 is converted to the title compound. EXAMPLE 26 ##STR38## (±)-2,3-Dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno-[1,2-b1pyrrole In a manner similar to that described in Example 23, the product of Example 22 is converted to the title compound. EXAMPLE 27 ##STR39## (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indole hydrochloride A solution of the product from Example 18 (0.77 g, 2.56 mmol) in 5 mL of THF was added dropwise to a suspension of lithium aluminum hydride (0.76 g, 20.0 mmol) in 15 mL of THF. The reaction mixture was stirred at room temperature for 18 hours and then heated to reflux for 1 hour. The reaction mixture was cooled to room temperature and quenched by the addition of small portions of Na 2 SO 4 -10H 2 O until no further gas evolution was observed. The reaction mixture was filtered and the filtrate was concentrated. The residue was dissolved in ether and treated with a saturated solution of dry HCl in ether. The solid which formed was collected by suction filtration and dried under vacuum (100° C.) to give the product (0.51 g, 72%) as a white solid mp 241°-253° C. Anal. (C 17 H 23 N.HCl) Calc'd: C, 73.49; H, 8.71; N, 5.04; Cl, 12.76 Found: C, 73.39; H, 8.73; N, 4.82; Cl, 13.16 EXAMPLE 28 ##STR40## (±)-2,3,4,5-Tetrahydro-8-methoxy-1-methyl-3a,9b-butano-1H-benz[g]indole A solution of the product from Example 24 (0.79 g, 3.08 mmol) and sodium cyanoborohydride (0.80 g, 12.7 mmol) in 10 mL methanol was treated dropwise with a 37% aqueous formalin solution (5 mL). The resulting solution was stirred at room temperature for 30 minutes, concentrated, and partitioned between 1N HCl (20 mL) and ether (20 mL). The organic phase was extracted with IN HCl (2×10 mL) and the combined aqueous extracts were washed with ether. The aqueous phase was made basic with K 2 CO 3 and extracted with CH 2 Cl 2 (3×20 mL). The combined organic extracts were dried K 2 CO 3 , filtered and concentrated to give the title compound (0.87 g, quantitative) as a white solid mp 100°-102° C. Anal. (C 18 H 25 NO) Calc'd: C, 79.66; H, 9.29; N, 5.16 Found: C, 79.52; H, 9.53; N, 4.71 EXAMPLE 29 ##STR41## (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno-[1,2-b]pyrrole In a manner similar to that described in Example 28, the product of Example 25 is converted to the title compound. EXAMPLE 30 ##STR42## (±)-2,3-Dihydro-7-methoxy-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole In a manner similar to that described in Example 28, the product of Example 26 is converted to the title compound. EXAMPLE 31 ##STR43## (±)-2,3,4,5-Tetrahydro-1-ethyl-3a,9b-butano-1H-benz[g]indole fumarate In a manner similar to that described in Example 28, the product from Example 23 (0.30 g, 1.32 mmol) and sodium cyanoborohydride (0.30 g, 4.77 mmol) was treated dropwise with acetaldehyde (0.20 g, 4.10 mmol) in 5 mL of methanol. Workup followed by crystallization of the fumarate salt from acetone gave the title compound (0.32 g, 65%) as a white solid mp 172°-173° C. Anal. (C 18 H 25 N.C 4 H 4 O 4 ) Calc'd: C, 71 13; H, 7.87; N, 3.77 Found: C, 70.90: H, 7.79; N, 3.75 EXAMPLE 32 ##STR44## (±)-2,3,4,5-Tetrahydro-8-methoxy-1-ethyl-3a,9b-butano-1H-benz[g]indole hydrobromide In a manner similar to that described in Example 31, the product of Example 24 (0.27 g, 1.13 mmol) and acetaldehyde (0.32 g, 7.12 mmol) are reacted. Workup, followed by crystallization from ether and HBr gave the title compound (0.27 g, 64%) as a white solid mp 248°-251° C. Anal. (C 19 H 27 NO.HBr) Calc'd: C, 62.29; H, 7.71; N, 3.82; Br, 21.81 Found: C, 62.39; H, 7.65; N, 3.77; Br, 21.98 EXAMPLE 33 ##STR45## (±)-2,3,4,5-Tetrahydro-1-propyl-3a,9b-butano-1H-benz[g]indole hydrobromide In a manner similar to that described in Example 32, the product from Example 23 (0.25 g, 1.10 mmol) and propionaldehyde (0.20 g, 3.47 mmol) was converted to the title compound (0.23 g, 60%) as a white solid mp 196`-198° C. Anal. (C 19 H 27 N.HBr) Calc'd: C, 64.92; H, 8.13; N, 4.07; Br, 23.09 Found C, 65.14; H, 8.06; N, 4.00; Br, 22.80 EXAMPLE 34 ##STR46## (±)-2,3,4,5-tetrahydro-1-(cyclopropylmethyl)-3a,9b-butano-1H-benz[g]indole fumarate In a manner similar to that described in Example 31, the product from Example 23 (0.25 g, 1.10 mmol) and cyclopropanecarboxaldehyde (0 23 g, 1.10 mmol) was converted to the title compound (0.26 g, 58%) as a white solid mp 150°-152° C. Anal. (C 20 H 27 N.1.2.C 4 H 4 O 4 ) Calc'd: C, 70.80; H, 7.62; N, 3.33 Found: C, 71.05; H, 7.67, N, 3.32 EXAMPLE 35 ##STR47## (±)-2,3,4,5-tetrahydro-1-phenylmethyl-3a,9b-butano-1H-benz[g]indole hydrochloride In a manner similar to that described in Example 32, the product from Example 23 (0.34 g, 1.50 mmol) and benzaldehyde are reacted. Workup, followed crystallization from ether and HCl gave the title compound (0 22 g, 42%) as a white solid mp 235-237° C. Anal. (C 23 H 27 N.HCl) Calc'd: C, 78.05; H, 7.98; N, 3.96; Cl, 10.02 Found: C, 77.60; H, 8.00, N, 3.34; Cl, 10.24 EXAMPLE 36 ##STR48## (±)-2,3,4,5-Tetrahydro-1-(2-propenyl)-3a,9b-butano-1H-benz[g]indole In a manner similar to that described in Example 32, the product from Example 23 is converted to the title compound. EXAMPLE 37 ##STR49## (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indol-8-ol A solution of the product from Example 24 is heated to reflux in 48% aqueous HBr until the starting material is consumed. The reaction mixture is poured into cold NH 4 OH solution and extracted into ethyl acetate. The combined organic extracts are dried (Na 2 SO 4 ) and concentrated to give the title compound. EXAMPLE 38 ##STR50## (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indol-8-ol In a manner similar to that described in Example 37, the product from Example 28 is converted to the title compound. EXAMPLE 39 ##STR51## (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol In a manner similar to that described in Example 37, the product from Example 26 is converted to the title compound. EXAMPLE 40 ##STR52## (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]-pyrrol-7-ol In a manner similar to that described in Example 37, the product from Example 30 is converted to the title compound. EXAMPLE 41 ##STR53## 3',3",4',4"-Tetrahydrodispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one A solution of triethylsilyl N,N,N',N'-tetramethyl phosphoramidate (J. Amer. Chem. Soc. 1978, 100, 3468) (1.1 eq.) in anhydrous ether is cooled to 0° C. and treated with acrolein (1.0 eq.) in anhydrous ether. The resulting solution is stirred at 0° C. for 4.5 hours then cooled to -78° C. and a solution of n-butyllithium (1.0 eq.) is added. The resulting solution is treated with the product from Example 1 (1.0 eq.) and stirred at -78° C. for several hours. The reaction mixture is quenched with brine and extracted with several portions of ether. The combined extracts are dried and concentrated. The residue is dissolved in THF and cooled to 0° C. and tetra-n-butylammonium flouride (5 eq.) is added. The reaction mixture is warmed to room temperature and worked up as above to give the title compound. EXAMPLE 42 ##STR54## 3',3",4',4"-Tetrahydro-7, methoxydispiro-[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan1-5"-one In a manner similar to that described in Example 41, the product from Example 2 is converted to the title compound. EXAMPLE 43 ##STR55## 3",4"-Dihydrodispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)-furan]-5"-one In a manner similar to that described in Example 41, the product from Example 3 is converted to the title compound. EXAMPLE 44 ##STR56## 3",4"-Dihydro-6'-methoxydispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)-furan]-5"-one In a manner similar to that described in Example 41, the product from Example 4 is converted to the title compound. EXAMPLE 45 ##STR57## (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide A solution of the product from Example 41 is placed in a high pressure reactor and dissolved in tetrahydrofuran. Ammonia is condensed into the solution and the reaction vessel is sealed and the reaction mixture is stirred at room temperature for approximately 24 hours. The reaction vessel is vented and the remaining solvent is concentrated to give the title compound. EXAMPLE 46 ##STR58## (±)-3',4'-Dihydro-2'-hydroxy-7'-methoxyspiro-[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 42 is converted to the title compound. EXAMPLE 47 ##STR59## (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H1indene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 43 is converted to the title compound. EXAMPLE 48 ##STR60## (±)-2',3,-Dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 44 is converted to the title compound. EXAMPLE 49 ##STR61## (±)-2'-(3-Aminopropyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol A solution of the product from Example 45, in tetrahydrofuran (THF) is added dropwise to a suspension of lithium aluminumhydride in THF. The resulting suspension is heated to reflux for 1 hour and then stirred at room temperature for 18 hours. The reaction mixture is quenched by the addition of small portions of Na 2 SO 4 -10H 2 O until no more gas evolution is observed. The resulting suspension is filtered and the filtrate is concentrated to give the title compound. EXAMPLE 50 ##STR62## (±)-2'-(3-Aminopropyl)-3',4'-dihydro-7',-methoxyspiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol In a manner similar to that described in Example 49, the product from Example 46 is converted to the title compound. EXAMPLE 51 ##STR63## (±)-2'-(3-Aminopropyl)-2',3'-dihydrospiro-[cyclopentane-1,1'-[1H]inden]-2'-ol In a manner similar to that described in Example 49, the product from Example 47 is converted to the title compound. EXAMPLE 52 ##STR64## (±)-2'-(3-Aminopropyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'(2',H)-NAPTHLENE]-2'-yl)propyl]carbamate In a manner similar to that described in Example 49, the product from Example 48 is converted to the title compound. EXAMPLE 53 ##STR65## 2,2,2-Trichloroethyl (±)-[3-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl[carbamate A solution of the product from Example 49 (1.0 eq.) and triethylamine (1.1 eq.) in CH 2 Cl 2 is cooled to 0° C. and a solution of 2,2,2-trichloroethylchloroformate (1.1 eq.) in CH 2 Cl 2 is added dropwise. The resulting solution is stirred at 0° C. for 30 minutes and warmed to room temperature. The reaction mixture is washed with bicarbonate, dried and concentrated t give the title compound. EXAMPLE 54 ##STR66## 2,2,2-Trichloroethyl (±)-[3-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)napthlene]-2'-yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 50 is converted to the title compound. EXAMPLE 55 ##STR67## 2,2,2-Trichloroethyl (±)-[3-(2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'[1H]inden]-2'yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 51 is converted to the title compound. EXAMPLE 56 ##STR68## 2,2,2-Trichloroethyl (±)-[3-(2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'[1H]inden]-2'-yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 52 is converted to the title compound. EXAMPLE 57 ##STR69## 2,2,2-Trichloroethyl (±)-3,4,5,6-tetrahydro-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 53 is converted to the title compound. EXAMPLE 58 ##STR70## 2,2,2-Trichloroethyl (±)-3,4,5,6-tetrahydro-9-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 54 is converted to the title compound. EXAMPLE 59 ##STR71## 2,2,2-Trichloroethyl (±)-3,4-dihydro-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 55 is converted to the title compound. EXAMPLE 60 ##STR72## 2,2,2-Trichloroethyl (±)-3,4-dihydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 56 is converted to the title compound. EXAMPLE 61 ##STR73## (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]-quinoline In a manner similar to that described in Example 23, the product from Example 57 is converted to the title compound. EXAMPLE 62 ##STR74## (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-4a,10b- butanobenz[h]-quinoline In a manner similar to that described in Example 23, the product from Example 58 is converted to the title compound. EXAMPLE 63 ##STR75## (±)-1,2,3,4-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 23, the product from Example 59 is converted to the title compound. EXAMPLE 64 ##STR76## (±)-1,2,3,4-Tetrahydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 23, the product from Example 60 is converted to the title compound. EXAMPLE 65 ##STR77## (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline In a manner similar to that described in Example 28, the product from Example 61 is converted to the title compound. EXAMPLE 66 ##STR78## (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-1-methyl-4a,10b-butanobenz[h]quinoline In a manner similar to that described in Example 28, the product from Example 62 is converted to the title compound. EXAMPLE 67 ##STR79## (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 28, the product from Example 63 is converted to the title compound. EXAMPLE 68 ##STR80## (±)-1,2,3,4-Tetrahydro-8-methoxy-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 28, the product from Example 64 is converted to the title compound. EXAMPLE 69 ##STR81## (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinoline-9-ol In a manner similar to that described in Example 37, the product from Example 62 is converted to the title compound. EXAMPLE 70 ##STR82## (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline-9-ol In a manner similar to that described in Example 37, the product from Example 64 is converted to the title compound. EXAMPLE 71 ##STR83## (±)-1,2,3,4-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol In a manner similar to that described in Example 37, the product from Example 66 is converted to the title compound. EXAMPLE 72 ##STR84## (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol In a manner similar to that described in Example 37, the product from Example 68 is converted to the title compound.

A novel series of tetracyclic amines, methods of preparation, compositions containing the amines, and methods for using them in the treatment and/or prevention of cerebrovascular disorders are disclosed.

FIELD [0001] The present invention relates generally to communications devices, and more particularly to mobile hand held communications networks. BACKGROUND [0002] Many people are familiar with mobile handsets. Mobile handsets are typically small electronic devices that communicate with a base station to place mobile calls. Many mobile handsets also perform other features in addition to placing mobile calls. For example, some mobile handsets are capable of transmitting data in addition to voice. [0003] A popular feature on many mobile handsets is push-to-talk. With push-to-talk a mobile handset user is able to push a single button to complete a call to a specific mobile handset, or some small number of mobile handsets. The mobile handset acts like a “walkie-talkie.” However, generally, instead of communicating directly to another “walkie-talkie” a mobile handset with push-to-talk typically communicates through a base station to another mobile handset using a single button push to initiate the connection. Additionally, like a “walkie-talkie” when using a mobile handset with push-to-talk, after a user pushes the button they are able to speak without having to wait for the other mobile handset to ring and the other user to answer. [0004] However, some delay between pushing the button and connecting to the other mobile handset may exist. It would be advantageous to try to lower that delay as much as possible. Additionally, while this delay may typically be more noticeable to a user using push-to-talk, or other single button push services, the delay may exist with other mobile handset services including, but not limited to mobile telephone calls and mobile data calls. It would also be advantageous to try to lower the delay as much as possible when using any other communications services that exhibit a delay when communicating with a base station or other transceiver. [0005] One cause of delay when beginning a mobile call, including push-to-talk, and data calls is related to how often a mobile communicates with a base station. Many current mobile handsets are designed to communicate with a base station at specific time intervals. These time intervals are the only time that the mobile handset can begin a mobile call. The longer the delay between intervals, the longer it is likely to take to set up a mobile call. It will be understood by those of skill in the art that the delay will be variable and somewhat random. Depending on when a user initiates a call relative to the next slot cycle. Slot cycle is the time when the mobile handset communicates with the base station. If the user attempts a call close to the next slot cycle, the delay may be relatively short, however, if the user attempts a call just after a slot cycle, the delay may be relatively long. [0006] As stated above one aspect to consider regarding mobile handsets is how often and when the mobile handset should communicate with the base station. Typically, the more often the mobile handset communicates with the base station the faster the mobile handset will be able to respond when the person using the mobile handset attempts to make a call. For example, if the mobile handset communicates with the base station every second, when a user attempts to make a call it will only be one second, at most before the mobile handset is able to communicate with the base station and start the process of placing the call. However, if the mobile handset only communicates with the base station every two seconds, then it could be as long as two seconds before the process of placing the call begins. [0007] So, to speed up placing a mobile call, the mobile handset should communicate with the base station as often as possible. However, communicating with the base station as often as possible has many drawbacks. Transmitting to the base station typically takes power. On a battery-operated device, this can be a critical consideration. Additionally, in many cases the more often a mobile handset communicates with a base station, the fewer mobile handsets that are able to use the base station. This is due to the fact that the base station typically has a limited number of transceivers to communicate with mobile stations. For this reason, each mobile station is given a time when it can communicate with the base station. Multiple mobile handsets are able to communicate with the base station by time-sharing. The more often a mobile handset communicates with the base station, the fewer other mobile handsets can communicate with the base station. For these reasons, and possibly others, the delay between communications between mobile handsets and base stations is not typically made arbitrarily short. [0008] Referring to FIG. 12 more details of communication between mobile handsets and base stations will be discussed. The diagram 700 includes a graph 704 . The graph 704 shows when a mobile handset 724 communicates with a base station 722 . The communication is shown as electromagnetic signals 720 . Communications occur at 707 , 709 , and 712 . It should be noted that this is only one possible example. The time between communications between base station and mobile handset may not always the same. [0009] Typically the slot cycle index is initially negotiated between the base station and the mobile handset. by the manufacturer. The number of clock cycles is known as slot cycle index. Slot cycle index is not a linear. Slot cycle index 0 indicates that communication occurs every cycle. Slot cycle index 1 indicates that a communication occurs every cycle. Referring back to FIG. 12 a slot cycle index 3 indicates that a communication occurs every four cycle. Slot cycle index above slot cycle index 3 are also possible. Slot cycle index timing can be summarized as follows, where x is the slot cycle index: TIME BETWEEN COMMUNICATION=1.28×(2 n ) For example, for slot cycle index 0 a communication occurs every 1.28 seconds, slot cycle index 1 is a communication every 2.56 seconds, and for slot cycle 2 a communication occurs every 5.12 seconds. Other slot cycle indexes are possible. Additionally, “negative” slot cycles are possible. In one possible implementation of “negative” slot cycles the number “n” in the equation above is a negative number. The use of “negative” slot cycles allows communication to occur more often than every 1.28 seconds. BRIEF DESCRIPTION OF THE FIGURES [0010] FIG. 1 illustrates a flowchart describing one method of dynamically changing a slot cycle index, according to one embodiment of the present invention. [0011] FIG. 2 illustrates a mobile handset user, in an embodiment of the present invention. [0012] FIG. 3 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0013] FIG. 4 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0014] FIG. 5 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0015] FIG. 6 illustrates one embodiment of a handset. [0016] FIG. 7 illustrates a base station, in an embodiment of the present invention. [0017] FIG. 8 illustrates a base station, a mobile phone, and a method of use, in an embodiment of the present invention. [0018] FIG. 9 illustrates a graph of a clock signal for reference timing, in an embodiment of the present invention. [0019] FIG. 10 illustrates a system and method for dynamically changing a slot cycle index, according to one embodiment of the present invention. [0020] FIG. 11 illustrates a graph showing several possible slot cycle priorities, in an embodiment of the present invention. [0021] FIG. 12 generally illustrates prior art involving communication between mobile handsets and a base station including a slot cycle graph. SUMMARY [0022] Many people use mobile handsets. As many users may have noticed, sometimes it can take a while to complete a mobile call. One thing that may affect is known as slot cycle index. The slot cycle index is the amount of time that the mobile handset must wait before communicating with the base station. The higher the slot cycle index the longer the mobile handset must wait before communicating with the base station. The lower the slot cycle index the shorter the delay. However shorter slot cycle priorities limit the number of mobile handsets that can communicate with a base station. Additionally, shorter slot cycle index typically increase the amount of battery power used by the mobile handset, commonly lowering standby and talk time. [0023] The slot cycle index is currently negotiated by a mobile handset and a base station. However, if the slot cycle index could be selected dynamically a mobile handset that operates more efficiently for the user would result. Talk time could be maximized when the battery, or other mobile power source is low, while connect time for a mobile call could be minimized when the battery is near fully charged or at times when the user is likely to make a mobile call. Additionally, location could be used to determine the likelihood that the user will make a mobile call. However, current network usage would typically need to be considered when determining if the slot cycle index should be changed. Mobile handset users could also charged for quicker response times, or mobile handset users on more expensive plans could be given typically faster response times. Many different things can be considered in determining when to adjust slot cycle index. More examples will be given below. [0024] Dynamically adjusting slot cycle index allows a mobile handset to, in some cases, operate more efficiently. In some cases the mobile handset may exhibit faster response time due to lower slot cycle index, while in other cases the mobile handset may use less battery power due to the higher slot cycle index. In addition, the service provider will be able to dynamically change slot cycle index to allow more users access to a base station. DETAILED DESCRIPTION [0025] Several methods of dynamically changing slot cycle index are possible. Referring now to FIG. 1 a flowchart 100 that illustrates one possible example will be discussed. [0026] The flowchart 100 shows one example of a method of dynamically changing slot cycle index. The flowchart 100 begins at 103 . In step 106 a request from a mobile handset to operate at a higher slot cycle index is received. The mobile handset may send a request to operate in a higher slot cycle index for several reasons. Typically, the occurrence of a trigger event will cause the mobile handset to send the request. Trigger events at the mobile handset can include the battery power available at the mobile handset, the time of day, or feature availability at the mobile handset. More details regarding trigger events will be discussed with respect to FIG. 3 . Additionally, trigger events that are generally related to specific devices, such as the mobile handset or the base station, as well as groups of devices such, as the network will be discussed with respect to FIG. 10 . [0027] It is determined if the current system loading will allow an increase in slot cycle index for the mobile handset in step 109 . If the current system loading will allow, the mobile handset is set at a higher slot cycle index in step 113 . As can be seen in this example, typically, the base station and the mobile station negotiate to determine if the mobile handset should operate in a higher slot cycle index. [0028] The flowchart 100 is one possible example of a method of dynamically changing slot cycle index. Other examples are possible. For example, a request may come from a base station instead of a mobile handset. In this example, the base station sends a request to the mobile handset to operate at a higher slot cycle index. For this example, as discussed with respect to FIG. 1 above, typically, the base station and the mobile handset negotiate to determine if the mobile handset slot cycle index should be changed. Additionally, slot cycle index may be increased, as shown, decreased, or kept the same based on different trigger events. [0029] Several examples of trigger events will be discussed below with respect to FIG. 3 below. FIG. 3 includes discussions of trigger events that may increase or decrease slot cycle index. In some cases different trigger events may be considered at the same time to determine if slot cycle index should be changed. The term trigger event is used throughout to describe an event that causes the method to change slot cycle index. However, in some cases the term trigger state may be better. For example, if several factors are considered at one time, it is the state of each factor that determines the outcome. Additionally, it may be the change of a single factor that causes the determination to occur. Alternately, several states changing could cause a determination to occur. In this application, the term trigger event will be used to describe a state, or change in state that causes a request to operate at a different slot cycle index to be transmitted. In FIG. 2 an example of a specific mobile handset user will be discussed. [0030] Some advantages include the ability to conserve battery power when the battery is low by raising slot cycle index. However, in some cases it may be determined that slot cycle index should be increased even though the battery is low. Additionally, system loading can typically, in some cases, be lowered if necessary during times users are using up network capacity. [0031] Referring now to FIG. 2 an example will be discussed with respect to a diagram 125 . The diagram 125 includes a sports stadium 127 , an office building 130 , and a road 131 . Additionally, the diagram 125 includes a car 133 and a house 135 . In the example of FIG. 2 a mobile handset user, Mary, begins her day at the house 135 . When at home, Mary does not tend to user her mobile handset. However, during her drive to work Mary tends to make many calls using her mobile handset. Mary's mobile handset requests a higher slot cycle index during times of day that the mobile handset is typically used. [0032] Typically, on her way to work Mary's mobile handset is set at a higher slot cycle index. When Mary arrives at work in her building 130 she continues to use her mobile handset throughout the day. The mobile handset typically operates in a higher slot cycle index. This enables Mary to complete calls more quickly typically. However, Mary's building is close to the sports stadium 127 . On days that sports events occur at the stadium 127 many people normally attend, and typically carry mobile handsets. The large number of people at the stadium 127 put a large load on the base station 140 that is near the stadium 127 . When the loading at the base station 140 is high, Mary's mobile handset is not allowed to operate at a higher slot cycle index. The base station 140 is able to communicate with more mobile handsets when the slot cycle index is decreased. [0033] It should be pointed out that the discussion of FIG. 2 is only one possible example. Dynamically modifying slot cycle index could occur for a variety of reasons. Additionally, not allowing slot cycle index to be changed could happen for a variety of reasons. Slot cycle index can be increased when a trigger event occurs, as will be discussed with respect to FIG. 3 or slot cycle index can be decreased when a trigger event occurs as discussed with respect to FIG. 4 . [0034] Referring now to FIG. 3 , a flowchart 200 will be discussed. The flowchart 200 begins at step 202 . At step 204 it is determined that a trigger event has occurred. The trigger event is evaluated in step 206 and a determination is made to request a higher priority slot cycle in step 209 . The request for a higher priority slot cycle is made in step 212 . In the flowchart 200 of FIG. 3 a trigger event occurs that causes a request for a higher slot cycle index. However, a trigger event can also occur that would cause a request for a lower slot cycle index, as will be discussed with respect to FIG. 4 . Many events can be considered trigger events. Several examples will be discussed below, however, other examples are possible. One example of a trigger event is battery power. Operating a mobile handset in a high slot cycle index state usually increases the amount of battery power consumed for a given period of time. High battery power may be a trigger event to operate in a higher slot cycle index. Conversely, low battery power may be a trigger event to operate in a lower slot cycle index. [0035] Another example of a trigger event is time of day. If the current time of day is one that a mobile handset user tends to make many calls, or one that the service providers expect many calls to be made, a request to operate in a higher slot cycle index may occur. Again, as with the battery power example, the converse is also true. If it is a time of day when it is unlikely that a call will occur, this may be a trigger event to operate in a lower slot cycle index. [0036] A third example of possible trigger events is system loading. Higher slot cycle index places increased demands on system resources. When system loading is low, slot cycle index may typically be increased without placing a burden on the base station that the based station is unable to meet. However, when system loading is high, one possible way to decrease these demands is to lower the slot cycle index on some mobile handsets. It is important to note that these are only examples. [0037] The examples discussed above and other examples discussed below will be factors considered when deciding to increase or decrease slot cycle index. In some cases several different trigger events will be considered before an increase or a decrease of slot cycle index is made. For example, if battery power is low, the time of day is one that a call is likely to occur, and the system loading would allow for an increase slot cycle index, the slot cycle index may be decreased to save battery power, even though two other factors would allow for an increase in slot cycle index. [0038] Another trigger event is location. The mobile handset may be in a location where the user has made one or more, possibly many, mobile calls in the past. In this case it may be advantageous to increase the slot cycle index of the mobile handset. However, typically, other trigger events will be considered. For example, as discussed with respect to FIG. 2 when Mary is at work but a sporting event is occurring near by, even though she usually makes many calls using her mobile handset, it may not be possible to increase the slot cycle index of her mobile handset because system loading is to large. [0039] Location may effect the decision to increase or decrease slot cycle index in another way. Location tends to effect the amount of transmit power needed to communicate with a base station. In locations where transmit power is high it may be advantageous to decrease slot cycle index. In locations where transmit power is low, it may be advantageous to increase slot cycle index. As with examples discussed above, transmit power can be considered in conjunction with other factors. [0040] In another example, battery power may be high, while system loading is low and time of day is one that a call is likely to occur, however, the mobile handset may be located at a location where a large amount of transmit power is needed to communicate with the base station. In that case it may be advantageous to operate in a lower slot cycle index. [0041] In some cases mobile handset users may pay for higher performance service. For example, users may be more to have higher slot cycle index. In some cases, higher slot cycle index may be included on higher priced plans as part of a package of services provided. [0042] In some cases it may be likely that when a call occurs another call may occur soon after. The fact that a call has recently occurred may be used as a trigger event to increase slot cycle index. One case where several calls in rapid succession tend to be likely is one button push services, such as push-to-talk. [0043] Additionally, in some cases a feature may exist that requires higher slot cycle index. Or, in some cases the carrier or the mobile handset may desires higher slot cycle performance. Feature availability may be a trigger event. When a feature is available, for example, due to mobile handset proximity to a base station that supports the feature, the availability of the feature may trigger an increase, or decrease in slot cycle index, depending on the requirements of the feature. As with other trigger events, several trigger events can be combined to determine if slot cycle index should be increased or decreased. [0044] As was discussed above, with respect to FIG. 3 , a trigger event may trigger an increase in slot cycle index, while another trigger event may cause a decrease in slot cycle index. As shown in FIG. 4 , a trigger event may cause a request for a lower slot cycle. FIG. 4 is a flowchart 225 . The flowchart 225 begins at step 227 . At step 229 it is determined that a trigger event has occurred. In step 232 the trigger event is evaluated and it is determined that triggers a lower slot cycle has occurred. In step 234 it is determined that a request for a lower slot cycle should occur. A lower priority slot cycle is requested at step 240 . Summarizing FIGS. 3 and 4 , a trigger event occurs and depending on the type of trigger event a request for a lower or higher slot cycle occurs. In some cases a combination of trigger events or current states may be considered when deciding to request a higher or lower slot cycle. Additionally, trigger events or states may occur in a mobile handset, at a base station, or they may be inherent in the service that a user has purchased. For examples, see FIG. 10 below. The combination of trigger events discussed above could occur in a combination of the mobile handset, and base station and could also be based on the service purchase. Advantages may include the ability to increase performance of a mobile handset during periods of time or in locations where a mobile handset user is likely to make a mobile call. [0045] It will be clear to those of skill in the art that the converse is also true. The lack of some trigger events may cause slot cycle index to be increased. [0046] Referring now to FIG. 5 , a flowchart 250 will be discussed. The flowchart 250 is similar to the flowchart 200 of FIG. 3 . The flowchart 250 includes the addition of several possible trigger events, listed at step 255 . Beginning at 252 , the flowchart 250 determines that a trigger event has occurred at step 255 . Step 255 is the same or similar to step 205 of FIG. 3 . Possible trigger events include, but are not limited to: available battery power, time of day, location, transmit power needed, system loading, priority, occurrence of a call, and feature availability. As stated above, several trigger events can be considered when determining if slot cycle index should be increased, decreased, or kept the same. Additionally, each trigger event may be given a different weight when determining slot cycle index. At step 260 a request for a slot cycle index change occurs. Step 260 of FIG. 5 is the same or similar to a combination of 212 of FIG. 3 and step 240 of FIG. 4 . [0047] Referring back to step 255 , low battery power would typically be considered a trigger event for a lower priority slot cycle because higher priority slot cycles typically consume more battery power. The converse is also true. A high battery power would typically be considered a trigger event for a higher priority slot cycle. It should be noted that this is only one example. It will be understood by those of skill in the art that “low” battery power and “high” battery power are not precisely defined here and may vary widely from one specific implementation to another. [0048] Power stored in a battery can be thought of as a predetermined percentage, for example, 100% or fully charged, 75% charged, 50%, 25% charged, etc. Generally the percentage charge of a battery can be a function of the battery voltage, which can decrease as the battery discharges. Thus the charged state of a battery in a battery powered mobile handset can be a trigger event. For example, if enough charge is stored in the battery to complete at least one call, this can be a trigger event to request a different slot cycle index. The percentage charge can also be a trigger event, for example, greater than 25%, 50%, or 75%. In an embodiment that uses a mobile power source other than a battery, reaching a predetermined level of mobile power can be a trigger event. [0049] In some cases battery power may be considered with other trigger events. Additionally, in some examples, battery power may not be considered at all. Specific trigger events used in any particular application can be customized depending on the needs of that particular application. Some trigger events will be discussed further with respect to FIG. 10 . Advantages may include the ability to change slot cycle index to conserve battery power when battery power is low. [0050] When placing a call, especially a push to talk call, it may be likely that several calls will be placed in rapid succession. Generally increasing slot cycle index when a call has recently been placed will tend to have the advantage of increasing the ability of the mobile handset to place calls rapidly. For example, slot cycle index can be increased when a call has been placed within ten minutes, thirty minutes, or some other period of time. [0051] Referring now to FIG. 6 , a mobile handset 280 will be discussed. The mobile handset 280 includes an antenna 284 . The antenna 284 is a transducer for coupling radio frequency signals to a transceiver 282 . The transceiver 282 includes a transmitter and a receiver for sending and receiving radio frequency signals. The transceiver 282 is coupled to a processor 295 . The processor 295 is used to perform processing function necessary for the mobile handset. It will be understood by those of skill in the art that the processor could be a single processor or multiple processors. Additionally, the processor could be a microprocessor, a microcontroller, or multiple microprocessors or microcontrollers, or similar devices. The processor could be a digital signal processor or multiple digital signal processors. The processor could be a combination of different types of processors, including, but not limited to microprocessors, microcontrollers, and digital signal processors. The processor could also be stand alone digital logic, programmable logic, such as field programmable gate arrays, complex programmable logic devices, or other forms of programmable logic. The processor could be any circuit capable of performing the steps included in the claims. The processor 295 is coupled to a memory 293 . The memory 293 is used to store information used by the processor 293 . [0052] A mobile power source in the form of a battery, 298 is coupled to the processor to provide power to the processor. It will be clear to those of skill in the art that the battery 298 may provide power to other circuits in the mobile handset. Additionally, the battery 298 may be other types of mobile power sources, for example, the battery 298 may actually be a fuel cell, or other mobile power source. Additionally, the mobile handset is enclosed by a case 288 . In many cases lowering the slot cycle index will tend to conserve battery power at the mobile handset. Advantages may also include the ability to increase a mobile handsets performance when placing a push-to-talk call. In some cases the push-to-talk call may connect more quickly. [0053] Referring now to FIG. 7 , a base station 330 will be discussed. The base station 330 includes an antenna 332 . The antenna couples radio frequency signals to a transceiver 337 . The transceiver 337 is coupled to a processor 349 . Additionally, the processor 349 typically communicates with a terrestrial communications network. The processor 339 is coupled to a memory. The base station 330 is enclosed by a case 334 . Allowing the base station to dynamically change the slot cycle index used by a mobile station will tend to have the advantage of allowing the base station to manage system loading. When system loading is high, slot cycle index may be decreased. Decreased slot cycle index decreases how often mobile handsets communicate with the base station. [0054] Referring now to FIG. 8 a diagram 375 will be discussed. The diagram 375 includes a mobile handset 280 . The mobile handset 280 is the same or similar to the mobile handset 280 of FIG. 6 . Additionally, the diagram 375 of FIG. 8 includes a base station 330 . The base station 330 is the same or similar to the base station 330 of FIG. 6 . The mobile handset 280 and the base station 330 transmit electromagnetic signals to allow information to be communicated between the two devices. It will be clear to those of skill in the art that the base station may communicate with multiple mobile handsets, including the mobile handset 280 . In some cases not all mobile handsets will have dynamically adjustable slot cycle index. In other cases, it is possible that all mobile handsets will have adjustable slot cycle index. Additionally, it is important to note that typically the base station 330 and the mobile handset 280 will negotiate to determine slot cycle index setting. Many different ways to negotiate slot cycle index setting will be apparent to those of skill in the art. For example, the multiple trigger events, as discussed above, can be combined. Different trigger events can have different “weights” associated with them when trying determine what course of action to take. [0055] Additionally, in some cases it may be advantageous to have some trigger events cause slot cycle index to change independent of any other trigger event. For example, when the battery is low, it may be advantageous to always lower slot cycle index regardless of the other trigger events. Similarly, when system loading is high, it may be advantageous to always lower slot cycle index. However, it is important to note that these are only possible examples. In other cases these examples may not apply. In some cases slot cycle index may be increased or kept the same when the battery is low or system loading is high. [0056] In another example, in some cases it may be advantageous to allow one device to dictate slot cycle index to another. For example, perhaps it would be advantageous to not allow a mobile handset to refuse a request to lower slot cycle index. In this example, assume that system loading is high. A base station that is communicating with a mobile station sends a request, or in this case, perhaps it can be considered a command, to operate in a lower slot cycle index. In this example, the mobile handset is required to operate in the lower slot cycle index. It again should be stressed that these are only examples. Other examples are possible. It will be clear to those of skill in the art that specific trigger events, specific “weightings” for trigger events, specific combinations of trigger events, and specific ways to negotiate dynamic slot cycle index can be determined based on the needs of a particular implementation. Many different possibilities will be clear to those of skill in the art. For brevity, only a few examples are shown here. Advantages may include the ability to lower power used to transmit between the mobile handset 280 and the base station 330 . This may be especially important when the battery on the mobile handset 280 is low. [0057] Referring now to FIG. 9 , a diagram 400 will be discussed. The diagram 400 includes a graph of a clock signal 402 . The clock signal 402 is a reference for timing of transmissions between a base station 330 and a mobile handset 280 . For example, the base station 330 and the mobile handset 280 of FIG. 8 . A graph 404 of a dynamic slot cycle is also shown on the diagram 400 . The graph includes a period of time when the handset 280 operates in slot cycle 1406 . After a trigger event 412 the mobile handset 280 operates in slot cycle 0 for a period of time. Another trigger event occurs at 419 . The trigger event 419 is a trigger event that causes a decrease in slot cycle index. After 419 the mobile handset returns to slot cycle 1 . FIG. 9 is only one possible example, other examples are possible. Changes in slot cycle can occur other than just changing from slot cycle 0 to slot cycle 1 . For example mobile handset could change from slot cycle 2 to slot cycle 4 . Slot cycle could be changed by multiple slot cycles in a single change, for example, as stated above, from slot cycle 2 to slot cycle 4 . [0058] As stated above changes in slot cycle could be based a combination of trigger events. For example, the trigger events could be combined in the form of a function. Additionally, the combination of trigger events could be weighted differently. Some trigger events could be considered more important than others. The trigger events could be combined in the form of a function. For example, slot cycle change could be a function of battery power available, system loading, and location. [0059] In one example battery power could be considered more important than the other two trigger events. In this example battery power could be given more weight in a function the determines if a trigger event should occur. [0060] Additionally, these trigger events could be continuously monitored. In another example the trigger events can be monitored continually. In yet another example, the trigger events could be monitored only when one or more trigger events change. It will be clear to those of skill in the art that this is only an example, other examples, using other trigger events, or other combinations of trigger events are possible. Advantages include the ability to change slot cycle based on the conditions during a specific time period. [0061] Referring now to FIG. 10 a diagram 475 is shown. The diagram 475 generally shows the relationship between a network 480 , a base station 482 , a mobile handset 485 , and services 489 . On the diagram under base station 482 location, system load, and feature availability are listed. These trigger events are typically associated with the base station 482 , however, other groupings are possible. For example, feature availability is listed under both base station 482 and handset 485 . Additionally, if the handset could determine system loading, then system loading could be listed under handset 485 . However, handsets do not typically have access to system loading information, so system loading information, so system loading has not been included under handset 485 . The diagram is meant to be general and to show typical groups of trigger events and what devices tend to monitor for those trigger events. But, as can be seen above, the lists are not exhaustive. [0062] The section for handset 485 includes a list of trigger events such as power, time of day, and feature availability. As stated above, the list is intended to be an example. The list is not intended to be exhaustive. Other trigger events are possible. Additionally, trigger events could occur related to headings such as base station 482 , handset 485 , and service 489 in ways not shown on FIG. 10 . For example, if a base station 482 is able to determine battery power available then power could be listed under base station 482 above. However, since typically, the base station 482 does not know the battery power available to a mobile handset 485 , power is not listed under base station 482 . [0063] As stated above, FIG. 10 also includes service 489 . Service 489 includes priority service. In some cases a customer may pay extra for faster call completion typically brought about by higher slot cycle index. In other cases the service may be a part of other prepackaged services. Advantages may include the increased revenue due to the ability to charge some customers for typically faster call completion. However, in some cases, the service may be included with specific calling plans. [0064] Referring now to FIG. 11 a diagram 550 is shown. The diagram 550 is similar to the diagram 400 of FIG. 9 . However, the diagram 550 shows several possible slot cycle priorities 559 , 562 , 568 , 571 and indicates that a mobile handset can switch between the different priorities. Using the diagram 550 , the different slot cycle priorities 559 , 562 , 568 , 571 can easily be compared. It can be seen from the diagram 550 that the higher the slot cycle index, the more often the mobile station communicates with the base station. It should be noted that higher slot cycle index is indicated by a lower slot cycle number. For example' slot cycle 0 is a higher slot cycle index than slot cycle 1 . The ability to dynamically change between slot cycle priorities has many advantages, as discussed above. Dynamically changing slot cycle index typically allows a mobile handset to operate more efficiently and in some cases adapt to the current state of the handset, the network, or the service purchased. [0065] Many examples are discussed above. However, these are only examples. Other examples are possible. Additionally, many advantages are discussed above. However, these are only possible advantages. Advantages may vary from one specific implementation to the next. Additionally, some advantages may be an important aspect of one implementation while unimportant or possibly not included in another. Embodiments should only be limited by the claims.

The slot cycle index is currently negotiated by a mobile handset and a base station. However, if the slot cycle index could be selected dynamically a mobile handset that operates more efficiently for the user would result. Talk time could be maximized when the battery, or other mobile power source is low, while connect time for a mobile call could be minimized when the battery is near fully charged or at times when the user is likely to make a mobile call. Additionally, location could be used to determine the likelihood that the user will make a mobile call. However, current network usage would typically need to be considered when determining if the slot cycle index should be changed. Mobile handset users could also charged for quicker response times, or mobile handset users on more expensive plans could be given typically faster response times. Many different things can be considered in determining when to adjust slot cycle index, such as, for example, battery power, time of day, or system loading. Additionally, combinations of factors can be considered to determine when to adjust slot cycle index.

[0001] The present application is a continuation of U.S. patent application Ser. No. 10/715,218 filed Nov. 17, 2003, now U.S. Pat. No. 7,062,475, which is a continuation of U.S. patent application Ser. No. 09/584,057 filed May 30, 2000, which is abandoned. FIELD OF THE INVENTION [0002] The present invention relates to the field of personal and personalized information services, and more particularly to the field of improved personalized computer user interfaces for database systems, more particularly those systems designed to organize information and information object references. BACKGROUND OF THE INVENTION [0003] Vendors of information appliances, such as personal computers, and even embedded devices with human computer interfaces, have often wrestled with providing an optimal presentation of customized of personalized information, both in the nature of the information to be presented, and the optimal presentation thereof. Personalization and customization of computer user interfaces is often in conflict with a desire for standardization and consistency. Thus, the more an interface is malleable to represent personalized factors, the less that interface represents a standard, and that deviation can lead to support and training difficulties. See, e.g., Horvitz et al, U.S. Pat. No. 6,021,403, expressly incorporated herein by reference. [0004] In order to customize computer user interfaces, typically the visual factors are treated as objects, such as view type, font, color scheme, wallpaper, sounds, icons, and the like, which may be altered globally or locally by altering a characteristic of the visual object. In order to personalize computer user interfaces, typically the layout of different types of information, such as news, weather, financial data and the like, is predicated by interests of the user. [0005] As a separate scheme, computer user interfaces may also track a user's activity, thereby creating a history. It is often desirable to facilitate common functions of programmable interfaces for the user and/or to recall recently performed operations that are desirable to be repeated or for which traceability is desired. Thus, many software constructs record a list of recently used files, which is then presented as a readily accessible list of potential choices for the user. Likewise, graphic user interfaces for operating systems and favorite lists for browsers are generally directly modifiable by the user to alter the selection and grouping of information-related objects presented. [0006] In a system having a hypermedia structure, information objects can be browsed by following links provided between each other. In conventional hypermedia systems, however, a problem may often occur in which a path that the user has followed is lost and the user cannot return to a desired location or the user becomes unable to make out his whereabouts in the system. This problem is generally known as the problem of lost path in the hypermedia system. [0007] Conventional hypermedia systems often have history files that tell the routes the user has followed. Generally, most of such history files simply list character information in the order in which the user has been browsing. Some of the history files indicate the hypermedia links in a tree structure to allow grasping of the connection state of the information objects, while others show the nodes in images reduced in size and sometimes referred to as thumbnails. [0008] Modern Internet browsers, such as Microsoft's Internet Explorer, and Netscape's Navigator provide access to a list of viewed Web pages, albeit through different means. This history is generated automatically based on actual Web pages viewed, and is non-editable by definition, except that Microsoft allows deletion of pages from the history list. Revisits to a Web page add additional versions of the page in the history list of Microsoft Internet Explorer. The browser history is acquired as a list of the Web page addresses referred to as URLs, or uniform resource locators, represented in the address input box of the browser. If a desired object is not identified by a representation in the address input box, it is not recorded or not definitively recorded, and indeed also cannot be appropriately added as a favorite. This history may thus incompletely define the state of the system, for example, when the system executes a script, applet or plugin, or other machine state not fully defined by the URL. In these cases, the history list is not usable to completely restore a prior state of the browser. [0009] A Uniform Resource Identifier (RFC 1630) is the name for the standard generic object in the World Wide Web. Internet space is inhabited by many points of content. A URI (Uniform Resource Identifier is the way you identify any of those points of content, whether it be a page of text, a video or sound clip, a still or animated image, or a program. The most common form of URI is the Web page address, which is a particular form or subset of URI called a Uniform Resource Locator (URL). A URI typically describes: the mechanism used to access the resource; the specific computer that the resource is housed in; and the specific name of the resource (a file name) on the computer. Another kind of URI is the Uniform Resource Name (URN). A URN is a form of URI that has “institutional persistence,” which means that its exact location may change from time to time, but some agency will be able to find it. [0010] In these known systems, only Web pages and downloaded elements are stored and recorded. In contrast, certain information, such as search queries that are not returned as part of a URL, as well as other arbitrary information selected by the user or server, cannot be included on the history list unless separately represented as a defined Web page. Thus, scriptlet and applet communications sessions may completely bypass the browser's ability to record the session progress, and thus make the browser unable to define the associated states and return to a prior state. [0011] A related problem occurs where the remote server employs cookies to define the Web page transmitted. If the cookie is changed, and indeed such changes may be made by the remote server during subsequent interaction, the state defined by the URL cannot be used to return the browser to the prior state. [0012] Cookies files stored in conjunction with user agents (web browsers, etc.) to hold small amounts of state information associated with a user's web browsing. Common applications for cookies include storing user preferences, automating low security user signon facilities, and helping collect data used for “shopping cart” style applications. See, RFC 2109, Network Working Group, HTTP State Management Mechanism. See, also RFC 2068, Network Working Group, Hypertext Transfer Protocol—HTTP/1.1 [0013] U.S. Pat. No. 6,018,344, expressly incorporated herein by reference, provides a system which, at a server, records requests for URLs by users, and provides a two dimensional map representing the usage history. U.S. Pat. No. 6,038,610, expressly incorporated herein by reference, provides a system and method for storage of site maps at respective servers, which are then communicated to client systems. [0014] Because of the limitations just discussed, among others, the implemented history list function employed by available browsers, i.e., standardized software executing on client systems for interacting with the Internet Web servers, fails to achieve the ability to return reliably the browser to a prior state in a number of common instances. [0015] In order to elucidate the problems involved in capturing the user's session history, it is necessary to consider the state of the client and server during a user session. In order to define the state of the machine, user activity is tracked. Storing a complete image of all processes, memory and registers is untenable, since literally this requires turning back the clock, with loss of all intervening information, which is either impossible or itself undesired. User activity may traditionally be tracked in a number of known ways. For example, a local computer application can track user activity. Likewise, any system interposed within a necessary communication path may also log user activity. A computer identifier, such as commonly included within a browser cookie, may be used to identify, and thus subsequently track the user, at a remote server. However, since the user may delete browser cookies, this technique is not reliable between sessions. In some cases, a communications address, such as an IP address, may be used to track a user; however, since users may share IP addresses, and IP addresses may be dynamically assigned, this technique is not globally reliable between communications sessions. SUMMARY AND OBJECTS OF THE INVENTION [0016] The present invention therefore seeks to provide improved human computer user interfaces, as well as supporting infrastructures. A particular problem confronting a user is an organization of information in a usage session or group of sessions. As a part of typical usage of an Internet system, users explore new content, through search engines, embedded hyperlinks, and the like. Often, the exploration is initially unfocused or noncommittal, as the user seeks to understand the field being searched. This initial exploration may include trial and error content review, as well as a comprehensive or exhaustive search of potentially relevant information. Typically, this exploration precedes normal and specific usage of the information, and thus the process invariably includes some degree of backtracking over previously reviewed information. [0017] The present invention thus provides enhanced methods for the identification, recall and organization of search paths and results. [0018] These are effected by improved methods of tracking, user activity, thus defining relevant states, and improved methods of presenting past user activity patterns, thus facilitating efficient usage thereof. [0019] In some cases, the exploration phase conducted by one user may be used to facilitate the search by another. Thus, the search path may be employed as an object that is employed by other users. [0020] These objects are created to record goal-directed behavior of the user, and may thus be relevant to other users having the same goals. Often, the goal is a more complex semantic concept than any single search represented within the set, and thus the identification of the goal may be a richer source of information regarding a user and the surrounding context than search queries. Once the goal is defined, an automated system may be provided to anticipate the user's requirements, which may then be presented to the user. Advantageously, when the detected or defined goal includes a transaction, an automated system is provided for presenting to the user transaction possibilities within the scope of the goal. Thus, for example, advertisements or other commercial information may be presented to the user. When the user's goal is non-transactional, the system may operate differently. For example, goal-related information from a variety of sources and general type advertisements may be directed to the user. [0021] Internet search engines and portals typically operate on a commercial subsidy model; this may include payment on a per-ad basis, a per-click-through basis, or a per-consummated transaction basis, for example. The use of targeting technology tends to favor transaction-biased models over ad-volume-based models. The present invention thus provides a capability for higher-level analysis of the user, at a goal rather than search query level. This technique may also be combined with user profiling, such that the status, context and history may be used to adaptively define the state of the system. See, U.S. Pat. No. 5,774,357, expressly incorporated herein by reference. [0022] The Internet's World Wide Web is typically considered a large set of Web pages that are aggregated into Web sites, with each Web site generally having a home page, from which other Web pages are accessible through hyperlinks. Normal use of the Web site may therefore entail multiple viewings of the home page. A diagram of normal usage therefore often appears like a hierarchal tree, with the home page at the root, other pages as branches, and potentially detailed pages or referenced database entries as leaves. Of course, embedded hyperlinks and other types of usage may complicate the diagram. [0023] Present browsers support “back” and “forward” functions, which allow a user to move through a historical list of visited Web pages to a referencing Web page (back), and referenced Web page (forward). However, where there is an ambiguity, the forward function provides the last visited page, and the back function provides a “higher level” referencing page. Thus, in a complex Web site, the back and forward functions may fail to provide full navigational capability. In short, history-of-use information is lost. [0024] The present invention addresses this problem by providing a “Session Mapping™” feature, in which one or more time lines are constructed from “history objects” that are, for example, each defined by a set of one or more Web pages visited by the user, and, potentially, activities performed by the user with respect to those Web pages. Thus, a user may return to a past-visited Web page by direct and random access thereof. This history object and related information, for example, may be stored as an information object at a server, and therefore, the user may potentially end his browser session without loss of the history context for that session. Likewise, this history object may be provided in editable format and further presented or transmitted to other users, allowing a sharing of a search experience, as well as a possible viral marketing advantage to the provider of the session mapping service or its sponsors. The history object may preferably also include a chronology, allowing a synchronized presentation of the history object, for example using Synchronized Multimedia Integration Language (SMIL) [Boston Specification (W3C Working Draft 3-August-1999; http://www.w3.org/1999/08/WD-smil-boston-19990803)]. [0025] Preferably, a history object is defined as a set of URLs, optionally with descriptive text, time, duration and/or number of accesses. This information is preferably presented with management and organizational tools for editing and organizing a set of history objects. The editing functions may include, for example, stripping of personal information from the URLs, for example where a user seeks to generalize the history object for third party use. Other functions may include deletion of certain steps or URLs, insertion of objects or URLs, appending and truncating sequences, saving and recalling, manual editing of command line entries and associated files, e.g., cookies, and archiving. Organizing functions include naming, renaming, ordering, deleting, copying, sending, receiving, sharing, privatizing, and “sanitizing” of history objects. The system may also provide a sanitizing function, for example, globally analyzing the URLs and associated objects to ensure that they do not contain personal information or private passwords (and if so, eliminating this information) and do not contain obscene or scandalous materials. This later analysis may include implementation of a (Mattel) Cyperpatrol-type filter along with semantic filtering. This filtering may encompass the history object itself, or require an analysis of the pages and objects referenced within the history object. [0026] A particular aspect of the present invention is that it allows a dynamic process to be defined. If a URL in the history object references a Web page whose underlying information changes, e.g., if the URL itself defines a search query on a database, and the contents of the database change, or the URL defines a dynamically defined object, then the subsequent access of the URL through the history object will represent the updated content. Thus, the history object may be used to define a set of content dynamically. [0027] On the other hand, sometimes a user seeks to define information statically as seen at a particular point in time. If the exact state of the URL is intended to be preserved, means may be established to cache the Web page content and reference the cached content rather than live Web page content, e.g., through an alias. This caching may be performed locally or through an external service. Typically, the history object will continue to appear to reference the source page (live) URL, although a hyperlink will direct recall of the cached copy. [0028] In still further instances, a user is interested in analyzing changes in the referenced Web pages. Therefore, both the cached and live versions of a Web page would be pertinent. Such analysis may also be performed locally, through a special application, or by corresponding application on a server. [0029] In some cases, the client computer request to the server does not correspond to a stateless. URL, and therefore the URL transmitted by the browser to the server would be insufficient to fully define the returned information. Rather, the returned information may relate to additional information, such as a sequence of events leading up to when the URL is transmitted to the server, or information defined by a cookie. The present invention, in fact, addresses both of these possibilities. With respect to the former, the history object directly addresses this issue by maintaining the sequence (path) by which a user achieves a given state of the system. With respect to the later, the present invention preferably encompasses a cookie manager, for example operating as an application within the client system, or on a remote server, which associates an appropriate cookie with each step within the history object, where necessary. Thus, the state of the cookie at the time of the original reference is preserved. As discussed above, according to one embodiment of the invention, the cookie manager resides within a server. In this case, the server acts as a third party proxy to the request. The client browser transmits URLs through the proxy server, and these URLs are modified as appropriate to achieve a desired state. In fact, a macro-sequence of URLs may be triggered to, define automatically a complex, path-dependent state with a single act by the user. Rather than acting as a complete proxy, requiring the proxy server to stand as an intermediary for all communications, the proxy server may spoof the client system's address (i.e., send a communication with a false IP address, causing the communicating partner to respond to redirect communications). It is noted that, while generally, spoofing is considered an undesirable security violation, in instances where the respective parties are aware and permissive of this activity, it may be an acceptable method. Alternatives to spoofing to achieve essentially the same results may be employed as well. Thus, in this asymmetric communication case, the proxy server selectively intercepts upstream communications and not the downstream communications. When the server downloads a cookie or applet to the client, this communication bypasses the proxy; however, the next time that modified cookie is uploaded, it passes through the proxy, and is captured at that time. [0030] It is noted that some of the functions implemented by the system according to the present invention are generally deemed to require security permissions or certifications. The user therefore will typically be requested to configure the security settings (or allow automatic reconfiguration by, or example, an applet) to permit system operation. The functionality gained from use of the system will, of course, provide sufficient benefit to the user to interest him in configuring the system (or allowing system reconfiguration) for such operation. Alternately, in most instances, the functions according to the present invention may also be implemented without requiring security setting reconfiguration, or in systems which do not support some of the functionality, such as scripts and applets. For example, displays may be presented as static web pages without scripts or applets, with necessary communication directly with the server or through a formal proxy server/application server. [0031] It is noted that this type of proxy may be present as a separate resource on the Internet or within a local area network. Furthermore, this proxy may be integrated with another proxy server, such as a firewall device. [0032] It is further noted that the cookie substitution and other aspects of the transaction need not be transparent to the proxy server; the information may be fully encrypted, since the proxy server acts in a content-neutral fashion. So long as the address information within each packet is open, and cookies are unambiguously identified, the proxy may perform its intended function. [0033] In order to allow this type of three-party communication, the content server system is preferably “fooled” into thinking that the communications are actually separate two-party streams. For example, the history object may form the basis of a communication to transmit a URL and possibly associated information, such as cookies, thus defining the desired state, to the proxy server. The proxy server then forwards the URL and optional cookie, each of which is possibly modified to achieve the desired state of the client system, to the content server. [0034] Correspondingly, the proxy server returns a simple redirect response to the client system, including an appropriate URL for the content server. The content server, in this case, responds to the spoofed (forged IP header) communication, effectively pushing the Web page to the client. The client system, in turn, since it has requested a URL from the content server via the redirect, sees the returned Web page as being the one requested, and accepts it. The proxy server function is therefore implemented without modification of the remote server, and with minimal modification of the client system (e.g., ensure security is set with permission to accept server-side redirect), and therefore maintains broad compatibility. [0035] The history object characteristics may be contained within an application or applet, including the desired functionality, and executed on the client system hardware. In this case, greater flexibility is available, but may result in certain incompatibilities. For example, the IP stack itself may be modified to implement the desired functions, which in this case would include a parallel transmission of packets to the remote server and history management server. Thus, a remote history management server would be assured a complete record of the transmitted information. Likewise, a local server may be provided proximate to the client system, through which the browser communicates. In this case, all transmitted and received URLs and Web pages may be managed locally. It is noted that an OCX (Microsoft ActiveX applet) may be able to perform these types of functions. [0036] A Session Mapping™ applet or scriptlet may also be provided on the client system to capture the URL information, which may then be stored or transmitted to a remote server. In this case, the Session Mapping™ applet or scriptlet typically does not have access to local operating system level functions, and cannot intercept or alter communications between the browser and stack, or stack and network interface. However, most common browsers do provide a function wherein the most recent URL is available for inspection. Thus, a Session Mapping™ applet or scriptlet may capture this information and convey it to a history management system. Likewise, cookies may be transmitted from the browser to remote servers when properly requested; thus, the appropriate cookies may also be communicated to the history management system. [0037] The Session Mapping™ applet according to the present invention is distinguished from the applet described in U.S. Pat. No. 6,035,332, expressly incorporated herein by reference, since the applet of U.S. Pat. No. 6,035,332 requires that the tracked Web page be served from a controlled or cooperating Web server, rather than any random Web server. It is also noted that the graphic user interface of U.S. Pat. No. 6,035,332 is dissimilar in key respects. [0038] A particular advantage of browser scripts is that no distinct download and installation is necessary. It is noted that some of the techniques described herein violate traditional security principles, and, but for the desirable functionality, might be considered intrusive. It is further noted that the techniques described herein may be used to implement functions other than history management. For example, a similar technique may be used to synchronize two or more client systems on the Internet; for each transaction, one system acts as a master, requesting a URL and also transmitting the URL and an optional cookie to a proxy site. At the proxy site, the URL is also requested, with the identical cookie available for upload. Thus, the states of the two (or more) systems will be synchronized. This technique would facilitate the sharing of a session experience on the Web with many other users. [0039] The techniques according to the present invention may also be used for remote logging and monitoring of users. [0040] According to the present invention, a Session Mapping™ applet may process a history object to recreate the original sequence (or a modification thereof), including an automatic sequencing of states. [0041] In performing a search, typically a large proportion of the pages visited will be irrelevant or secondary. For example, a user searching for jewelry may submit the search query “diamond” into a search engine. The search query URL is trapped by the Session Mapping™ applet or scriptlet and either processed locally or transmitted to the host site. The user is then typically presented with a list of Web pages (URLs) that correspond to the search query. Some of these URLs may contain content only, without opportunity for purchase, while others may include purchasing opportunities. Some responsive URLs may, in fact, be irrelevant or distasteful. Often, the user must explore the presented information in order to categorize the sites. In some instances, the user may search the topic using a variety of search terms or execute the same search query on a variety of search engines. [0042] After the user has completed a search and acquired background information, the next step is typically to employ that information gainfully. According to the prior art, the user was forced, using memory or rudimentary tools, to relocate the best sites from the search, which typically occurred before a complete analysis of the available information. This prospect often lead to a truncation of a search when a minimally-acceptable Web page or well-known site was identified, rather than facing the prospect of finding it again using inadequate tools. According to the present invention, the user is permitted to complete his search and investigation, with reasonable prospects of easily finding and retrieving any previously visited sites, including defined states thereof. [0043] As each Web page is visited, it is added to a list, and preferably maintained and presented in a “Personal Services Infrastructure”™ (PSI™) format, which is displayed on the screen generated by a browser and/or applet. For example, this information is presented in a marginal frame of a browser, or within a visually presented applet. Therefore, when the user seeks to retrace his steps, each significant hop or state is separately listed, possibly including additional descriptive information, such as the duration of content viewing, the time(s) of viewing, and the like (the duration of a visit being, among other things, a key indicator of value for the user). Furthermore, each entry may be provided with certain editing features, for example, the URL, description and order may be edited. [0044] In defining a state of the client's session, a number of options are available. Commonly, each Web site is accessed through a special Web page called a home page. Often the Web site home page is associated with an Internet Top Level Domain name (TLD), or domain name, such as WWW.MYSITE.COM. Therefore, the membership of web sites is often classified based on the associated domain name. Other methods are available, however, to determine membership within a Web site. According to one embodiment of the invention, each Web site is provided with a separate region within a Session Map™. When the user selects a respective region of the Session Map™, the chronological path of the user within that Web site may be expanded, possibly with a hierarchal representation of the organization of the site (or limited to pages hyperlinked by the user), or to a linear session map opening from within the segment of the session map. Of course, the user may traverse a path that seamlessly traverses a number of TLDs or Web sites, so that this distinction may be arbitrary. Thus, other modes of presentation may be offered to the user, based on the stored information and possibly an analysis of the Web page content referred to thereby. Another organizational method relates to the amount of time that a user dwelled on a web page, or composite set of pages, e.g., a site; the longer the dwell, the higher the implied importance. A further organizational principle involves analyzing the use of a Web page as a hub; if the user returns to a page a number of times in the course of an activity, that page is considered an important hub, with Web pages traversed thereby considered spokes. This analysis, it is noted, does not require that the TLD be the same for the hub and spokes. [0045] Another organizational principle seeks to employ Web page expiry data. Typically, a static home page will not expire, while dynamically generated pages quickly expire. Pages that have associated ID numbers (or alphanumeric sequences) typically result from a sequence of actions, wherein the user session, is initiated and tracked by means of the ID number. In order to recreate the state of the system, the series of URLs and forms which lead to the desired URL must be replicated, allowing the ID number to change according to the newly recreated sequence. Thus, the history object is processed by an application to parse URLs and construct synthetic URLs representing the desired states, without forcing the user to track manually the prior actions. In this case, when a user selects a Web page that requires a series of interactions to recall from the server, this series of interactions is automatically invoked from a logical starting point. In representing this to the user, it is the lower level Web pages within a hierarchy that take on greater importance, with the higher level Web pages serving merely as conduits. Thus, if the history display is collapsed, it is the end Web page that is represented, and the path toward that Web page becomes unveiled only when the user specifically selects the end Web page. [0046] In this regard, the history of use may be represented as a set of chains, with the top and/or bottom of each chain defining a relevant feature or identifier, and the intervening portions having presumed lower importance. Each node within the chain may be represented by a separate history object. Thus, a two dimensional data set may advantageously be normally represented as a one dimensional “time line,” preferably with only one hierarchal chain visible at a time, and otherwise merely with an identification of the chain available for access by the user. [0047] An example where the highest level is relevant to the user is, for example, at a corporate Web site, where a user is investigating various aspects of the company. The home page is therefore an appropriate starting point and identifier for the string of events. [0048] On the other hand, an example where the highest level is not relevant is where the user is searching a set of content through a portal. In this case, the identification of the portal is nearly irrelevant. The search query, however, defines the data set, with the retrieved and inspected URLs or Web pages encompassing the relevant material. Thus, the string is preferably defined by the search query. [0049] The present invention provides a procedure that records in detail a history of a search, notwithstanding that a respective search engine does not or cannot do so itself. The present invention therefore seeks to trap or capture detailed information about the path taken by the user in completing a task, including scriptlet and applet usage, regardless of which search engine or server is accessed for information, and preferably allows a standard browser to be employed. [0050] According to a preferred embodiment of the invention, the history is provided for each session, and extends for the duration of the session. The history is preferably presented as a time line extending horizontally, which may be scrolled horizontally or which is wrapped in successive rows, as the listed history exceeds the column width. Preferably, the time line also captures the beginning and end time of each state, or the duration, or both. The time-line entry for each page or step may be annotated or provided with descriptive text, which may be provided by a history object, automatically generated from the history object, or manually associated with the history object. Preferably, the time line information includes details sufficient for the user to understand the nature of the transition between successive history objects. Preferably, also, the time-line is searchable by text or by characteristic, such as URL, title, date, time. [0051] According to the present invention, this presented history need not encompass a literal record of the path taken by the user, but may, in fact, include information derived from a variety of sources. First, the information list may be enhanced to include advertisements or marketing information. This information is preferably derived either from a user profile, and predicted to be relevant to the user based thereon, or from the search context, and thus related to the information included within the history. Therefore, it is apparent that a presented history bar, including history objects and supplemental commercial objects, may be a source of commercial subsidy. By linking the commercial subsidy with a useful feature, consumer acceptance thereof may be enhanced. [0052] The information may also be enhanced by analysis and presentation of additional content, distinct from the actual history. In some cases, this enhanced information may be identical to the advertisements; thus, where a user is seeking to make a purchase, and the search is for relevant vendors, the enhanced information is an advertisement of the type sought by the user. In other instances, the advertisements are of a general nature. Additionally or alternatively to advertising information, other enhanced information may be provided. For example, hints or suggestions, motivational messages, or other information may be automatically or manually inserted. [0053] In some instances, the system is not supported by commercial subsidy. Therefore, the enhanced information presented may take the form, for example, of goal directed enhanced information or status information. [0054] The graphic display objects according to the present invention may also include user interface functions for performing complex tasks or URL references. Thus, in contrast to prior systems presenting a user history as a set of URLs accessed by the user, the present invention provides enhancements to the accessible functionality with respect to identifications of past activities. [0055] Typical functionality which may be made available, as appropriate, include “summarize page,” “find like sites,” “add to favorites,” and “add to shopping cart,” “vote on value of site (or product),” “see others' votes,” “make a note,” “see other users' notes,” or an omnibus service icon or control that brings up a group of choices. [0056] It is therefore an object of the invention to provide an apparatus, comprising means for automatically tracking a URL path of a user; and means for displaying the URL path of the user. [0057] It is a further object of the invention to provide a human computer interface enhancement for an object browser, each object having an object resource locator, comprising means for automatically logging an object resource locator traversal history by the user; and a software construct, executable for defining a display pane in conjunction with the browser, said display pane comprising a set of hyperlinks and associated human-readable tags for object resource locators. [0058] It is a still further object of the invention to provide a history display system, comprising means for automatically storing a history of object references by a user; means for editing, by the user, the stored history; and means for display of the history, wherein said display hyperlinks to the referenced objects to allow arbitrary selection of an object. [0059] It is another object of the invention to provide a history display system, comprising means for automatically storing a history of states induced by a user; means for editing, by the user, the stored history; and means for display of the history, wherein said display hyperlinks to the referenced states to allow arbitrary selection of a historical state. The display hyperlinks are preferably displayed linearly, in chronological order. The display hyperlinks may also be displayed in hierarchal order, and may include importance-weighting information. [0060] It is a further object of the invention to provide a method of trapping URL references in an unmodified Web browser, comprising the steps of providing an applet executing in association with the Web browser, storing a current URL as a favorite within the browser, and capturing a last saved favorite URL from a favorites list. [0061] It is a still further object of the invention to provide a method of trapping URL references in an unmodified Web browser supporting frames, comprising the steps of loading a Web page from a cooperative server in a first frame; identifying a desired URL with the browser to request an Internet resource in a second frame, providing a script in the first frame to capture the identified URL in the second frame and transmit it to the cooperative server, and downloading, from the cooperative server to the Web browser first frame, a sequence of identified URLs. BRIEF DESCRIPTION OF THE DRAWINGS [0062] The purpose and advantages of the invention will be apparent to those skilled in the art from the following detailed description in conjunction with the appended drawings, in which: [0063] FIGS. 1A 1 E show sequential states of a history display applet; and [0064] FIG. 2 shows a Web browser user interface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 [0065] A first embodiment of the invention provides a system which operates in conjunction with a modern Web-enabled computer system with a standard browser installed. For example, a so-called WinTel (Intel Pentium III Processor, executing Microsoft Windows 9X or NT/2000 software) standard personal computer and either Netscape Navigator or Microsoft Internet Explorer, both of which are JavaScript and Java enabled, and frames-capable. Alternately, an Internet appliance platform (e.g., designed specifically for Internet usage rather than general purpose home or office tasks) may be employed. The system communicates with a remote server which is provided as discussed herein. [0066] A particular aspect of this embodiment of the invention is that enhanced features are provided for a standard browser system by means that do not require use of non-standard browsers, a special installation procedure or a computer reboot. Thus, the system provides broad compatibility, platform independence, portability, and a low probability of causing conflicts, system bugs or instabilities. The server-side hardware technology is also standard, while the server application software is custom. [0067] By operating within frames, the browser permits two Web pages to be displayed simultaneously and to be interactive. This communication or interactivity occurs within the browser and generally is subject to certain security controls. Accordingly, certain security measures that seek to limit inter process communications and preemption must be disabled. [0068] FIGS. 1A 1 E show a sequence of Session Maps™, generated by an applet executing within the user's web browser. In the Session Maps™, a user's progressive search on the Web for a diamond ring merchant is traced. Each frame represents a step, and any previous step can be returned in one click by treating that frame as a hyper-link. In the first step, shown in FIG. 1A , the user is represented at the home page, “Double Agent”. In the second frame, shown in FIG. 1B , the user accesses the “Double Agent” support page. In the third frame, shown in FIG. 1C , the search query itself, “diamonds,” is captured. In the fourth frame, shown in FIG. 1D , the user selects a taxonomic class, “jewelry” (which is distinct from, for example, baseball, industrial, and graphic images involving the same word). The fifth frame, shown in FIG. 1E , captures user's finding of a relevant Web page, “Diamond Depot.” The icons in the fifth frame represent a set of single-click services available to the user, with respect to the represented Web page. These services include “find like sites,” “save to favorites,” and “add to shopping cart,” which are represented as icons within a respective frame, where appropriate, and “summarize page,” represented by an icon external to each frame within the chain. For example, the shopping cart is available only for Web pages compliant with a shopping cart standard associated with the system, while the find like sites, save to favorites and summarize page are available for Web pages in general. Other possible services available to be offered through icons associated with the segments of the session map include: make an annotation; see other user's annotations or comments; vote on the worth of a site; see others' votes; see review information; compare price; see address, phone, e-mail and/or other contact information about a web site. [0069] In practice, the user calls up a URL 1 in the browser 10 from a cooperative remote server which provides a pair of frames; a first frame 3 a controlled by the cooperative remote server, having an associated executable software construct, e.g., JavaScript, and a second frame 3 b for display and manipulation of content. The user, within the second frame 3 b or in the address bar, identifies a desired URL 1 , for example by typing or hyperlinking. The JavaScript construct captures the URL 1 , which is then transmitted to the cooperative remote server. [0070] The cooperative remote server then uses the acquired URL 1 , which is transmitted in a form that identifies the browser system or user thereof, to construct a history of use for the session, called herein a Session Map™. The history of use is then transmitted back to the first frame 3 a , and displayed for the user, including a set of hyperlinks, each defining a respective prior state of the system and allowing return thereto. [0071] The history of use is preferably displayed with a second JavaScript construct, in the form of a time line 4 , for example disposed horizontally at the bottom of the screen. The remote server analyzes historical sequences in order to define goal-directed behavior sets and to segregate distinct goals. This segregation is based on conceptual factors, such as the relation of sequential URLs, e.g., hierarchal relation within a Web site or file storage system, time spent at particular Web pages or web sites, hiatus between uses or activity, semantic analysis or search queries or Web pages, as well as layout issues, such as an optimum number of displayed behavior sets, e.g., five displayed horizontally across the screen, complexity of each behavior set, and the like. [0072] The conceptual analysis may also seek to separate mixed concepts. For example, a user might be conducting two or more searches simultaneously, which may be related or unrelated. If these are related, the desired Session Map™ consolidates the histories and resolves ambiguities or artifacts. If these are unrelated, the desired Session Map™ isolates the trails, either as separate goal directed behaviors in the displayed linear sequence, or as a separate time line sequence. [0073] Each goal directed behavior identified in the time line display represents one or more states of the browser. If the number of goal directed behaviors exceeds the display space, then the display applet may provide scroll functions. Alternately, the display may be provided within a frame, with scrolling supported by the browser and/or operating system. [0074] The remote server seeks to provide, for each set of states, a semantic description thereof. In some cases, a graphic or acoustic description or label is preferred. Therefore, the present embodiment may support flexible labeling, including text, icon, thumbnail graphic, sound clip, or the like. The remote server may derive these labels by first, an analysis of the URLs, to determine whether the URL conveys a useful semantic label. For example, in many cases, a search engine query is a part of the URL and is descriptive the content of the Web page, as well as the associated set of Web pages. In other instances, the URL will be uninformative. In that case, the remote server may request the page, and perform an analysis thereof, to generate a summary or topical statement (or, if appropriate, musical clip, icon or thumbnail). The result of the analysis is transmitted to the browser, for display associated with a hyperlink. When the user selects the hyperlink, the entire associated chronological string is revealed. This string may be stored internally within the browser, or downloaded from the server. According to one embodiment, the search history is presented as a hierarchal tree, with each node of the tree representing a URL, and being hyperlinked thereto. Example 2 [0075] The present invention provides a set of Mini Agent™ functions that may be associated with objects, for example representing web pages or web sites. These are described with respect to FIG. 2 . [0076] A first Mini Agent™ function, providing a summarize page function, is accessed by selecting a hyperlink icon 11 associated with a history object representing a Web page. The icon 11 , for example, shows a script lower case serif “i”, representing “information”. The hyperlink, in turn, includes an identification, e.g., URL, of the Web page, which is passed to a summarizer server. The summarizer server receives the URL, and accesses a database, to determine whether an existing summary exists for the URL. If so, this is returned to the user. If not, the summarizer accesses the URL, and performs a semantic (or other content-dependent) analysis of the corresponding Web page, and optionally objects incorporated into the Web page. As a result of the semantic or other content-dependent analysis, a brief message is passed to the user, providing a Web page summary. A preferable semantic analysis analyzes the Web page text to parse context-defining words or phrases, of which many web pages have few, and transmits these parsed words and phrases to the user. An editor may also analyze Web pages and, for example, store manually generated summaries in the database. [0077] A second Mini Agent™ serves to “find like sites”. This is represented by an icon 12 corresponding to the mathematical equivalence symbol. Like the summarize page function, the function is accessed by selecting a hyperlink icon associated with a history object representing a Web page. The hyperlink, in turn, includes an identification, e.g., URL, of the Web page, which is passed to a similar site server. The similar site server receives the URL, and accesses a database, to determine whether an existing record, defining a set of similar sites, exists for the URL. If so, this is returned to the user. If not, the similar site server accesses the URL, and performs a content-dependent analysis of the corresponding Web page, and optionally objects incorporated into the Web page. As a result of the content-dependent analysis, a query, for example a Boolean query or other query type, is passed to an Internet search engine. [0078] Alternately, the classification of the Web page within a taxonomic hierarchy may be determined, the similar pages being defined as those that are similarly classified. The resulting list of similar sites is passed to the user. A human editor may also analyze commonly visited Web pages and, for example, store manually generated sets of similar sites in the database. Likewise, a collaborative filter may be employed to provide “similar” pages based on a probability of being accessed temporally proximate in time to the respective Web page by a group of persons. [0079] A third Mini Agent™ is “add to favorites”. This is represented by a thumb-tack icon 13 . In this case, the function does not represent a URL, but rather a script applet which executes within the browser to add the respective URL of the associated web page to the favorites list maintained by the browser. This script is typically defined distinctly for each history object. [0080] A fourth Mini Agent™ is “add to shopping cart”. This is represented by an “S” icon 14 . An electronic shopping cart is an electronic store, associated with an individual user, identifying objects for purchase. In this case, the implementation is in some sense similar to that described in U.S. Pat. No. 5,960,411 (Hartman, et al., Sep. 28, 1999), expressly incorporated herein by reference, although the functionality differs. This function may be implemented in two ways. First, the hyperlink may invoke an applet, and indeed may have a context sensitive functionality, i.e., the icon representing the function will vary depending on the Web page or content thereof, or the status of the Web page and/or user system. Second, the existing shopping cart hyperlink from the referenced Web page may be copied or emulated as the hyperlink associated with the icon, and therefore a selection of the icon representing “add to shopping cart” will have the same effect as a selection of that hyperlink from within the Web page itself. [0081] The “add to shopping cart” functionality may be limited to compliant Web sites, providing special support for this functionality, or be available to all sites that have an accessible shopping cart function. [0082] For example, a Web page identified by a URL represents a description of a single item available for purchase. The user, in the midst of a search for the item, may not be ready to consummate a sale, and thus may not wish to place the object in a “shopping cart”. Rather, only after a search is complete will a user identify the item and most preferable vendor. [0083] Using the “add to shopping cart” icon, the user may, without reopening the web page, directly add the item to a shopping cart, which indeed the shopping cart may be consolidated for a number of vendors and/or different that the shopping cart normally provided for user of the Web site. At a later point in time, the user may then “check out”, or provide transactional details to close the purchase for objects in the shopping cart. [0084] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein. The term “comprising”, as used herein, shall be interpreted as including, but not limited to inclusion of other elements not inconsistent with the structures and/or functions of the other elements recited.

A system and method for tracking a user history, for presentation thereof within a browser display. An executable software construct operates at a client machine to trap object references, which are then transmitted to a server. The server analyzes the object references and organizes them into a display structure. The display structure is then displayed within the browser, including hyperlinks to allow the user to select a prior system state to which he seeks to return. Preferably, the software construct also manages objects associated with the object reference, for example cookies associated with URLs, in order to assure full definition of the desired state. The display structure may also be provided to browsers distinct from the originating browser.

[0001] This application claims the benefit of the Korean Application No. P2001-10321 filed on Feb. 28, 2001, which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a method for controlling a memory in a digital system. [0004] 2. Background of the Related Art [0005] In embedded systems developed recently, there are ones that require processing and managing of a large amount of data. For an example, the digital system, such as a digital TV receiver, employs a web data used in a computer environment, or a data received from, and required for broadcasting, or an additional data. Recently, a broadcasting for transmission of data is under preparation. [0006] A current data base system developed and used for more convenient and effective processing of a large amount of data uses disks for recording data, and uses techniques of transaction management, query handling, synchronism control, indexing, hashing, and the like. [0007] Moreover, though a main memory resident type data base system that is made possible by development of a memory size also has a main data base on the memory, in most of the cases, the main memory resident type data base system is based on disks which can back up the main data base. The system having such a disk makes no assumption of a limitation of a maximum storage capacity of data. [0008] However, the case is limited, in which the disk is based in the embedded system actually, and, though memory technologies are developing currently, a system only having the memory is required to assume very limited use of the memory in comparison to a disk, to require a system that manage data in the system only having a limited memory. [0009] Moreover, though it does not matters for a system having an amount of data fixed in advance required to be stored in the system, there can be a storage demand greater than a memory size capable to store in a system the data is kept added, erased, and queried because a maximum required storage capacity is not fixed. SUMMARY OF THE INVENTION [0010] Accordingly, the present invention is directed to a method for controlling a memory in a digital system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. [0011] An object of the present invention is to provide a method for controlling a memory in a digital system having a limited size of memory, which can minimized a system performance deterioration, and facilitates storage of data greater than the limited capacity of the memory, [0012] Another object of the present invention is to provide a method for controlling a memory in a digital system, which has advantages of the present data base system, such as avoidance of duplication of data, and an easy access to a data, and the like. [0013] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [0014] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the method for controlling a memory in a digital system includes the steps of (a) dividing the memory into a plurality of fixed sized memory blocks, (b) defining at least one of the memory blocks as a region for compression/decompression, (c) assigning compression priorities to rest of the memory blocks except the memory blocks defined as region for compression/decompression, and (d) making the memory blocks to deal with an external data received according to an external command, and carrying out compression/decompression of data required in the dealing with the external data according to the compression priorities. [0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0016] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: [0017] In the drawings: [0018] [0018]FIG. 1 illustrates a block diagram showing a system of a digital TV receiver in accordance with a preferred embodiment of the present invention; [0019] [0019]FIG. 2 illustrates a flow chart showing the steps of a process for controlling a memory in a digital system in accordance with a preferred embodiment of the present invention; [0020] [0020]FIG. 3 illustrates a flow chart showing the steps of a process for inserting a data in a memory in a digital system in accordance with a preferred embodiment of the present invention; [0021] [0021]FIG. 4 illustrates a flow chart showing the steps of a process for erasing a data from a memory in a digital system in accordance with a preferred embodiment of the present invention; [0022] [0022]FIG. 5 illustrates a flow chart showing the steps of a process for up-dating a data stored in a memory in a digital system in accordance with a preferred embodiment of the present invention; and, [0023] [0023]FIG. 6 illustrates a flow chart showing the steps of a process for reading a data stored in a memory in a digital system in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0024] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In this embodiment, a digital TV receiver is taken into account among the digital systems. FIG. 1 illustrates a block diagram showing a system of a digital TV receiver in accordance with a preferred embodiment of the present invention. [0025] Referring to FIG. 1, the digital TV receiver includes a tuner 10 for receiving a digital broadcasting signal, a TP (transport) signal analyzer 20 for analyzing a TP signal from the digital broadcasting signal, to detect an audio signal and a video signal, a separator 30 for separating, and respectively decoding the audio signal and the video signal detected at the TP signal analyzer 20 , a decoder 40 for decoding the audio signal and the video signal decoded at the separator 30 , and a microcomputer 50 for controlling parts of the TV receivers. [0026] The microcomputer 50 divides channel data, program data, and information data received through the tuner 10 into fixed size blocks, stores in the memory 90 , and manages the stored data blocks. [0027] The digital TV receiver also includes an OSD (On Screen Display) processor 70 for providing an OSD text, and a display 80 for selectively superimposing the audio signal and the video signal decoded at the decoder 40 with the OSD text from the OSD processor 70 , and displaying on a screen. [0028] The microcomputer 50 in the digital TV receiver includes a storage managing module 51 for storing all the data from the tuner 10 in forms of data blocks by indexing or hashing, and carrying out a function to find a desired block from the stored data blocks quickly, a request processing module 52 for facilitating storage of a desired data in the memory 90 , or erasing or finding the desired data from the memory, a synchronism control module 53 for processing various requests on the sane time, and a memory managing module 54 for managing the memory 90 with the memory 90 divided into same sized blocks. [0029] The operation of the digital TV receiver of the present invention will be explained with reference to the attached drawings in detail. FIG. 2 illustrates a flow char showing the steps of a process for controlling a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention, [0030] Referring to FIG. 2, the memory managing module 54 in the microcomputer 50 divides the memory 90 , to be used as a storage space, into fixed size blocks. Then, memory managing module 54 combines at least one of the memory blocks and designates as a compression/decompression region for temporary storage of a compressed data, or compressing a data. [0031] The memory managing module 54 records a number of access times to the data in each memory block, and measures an access frequency of the memory block based on the number of access times. The memory managing module 54 sets up priorities of compression of the memory blocks based on the access frequency for compressing data when a capacity of the memory 90 lacks. The lower the frequency of access, the higher the compression priority, Then, the microcomputer processes the received data. [0032] The data processing includes data insertion, data erasure, data up-dating, and data read. The steps of the data processing will be explained with reference to the attached drawings. FIG. 3 illustrates a flow chart showing the steps of a process for inserting a data in a memory in a digital system in accordance with a preferred embodiment of the present invention. [0033] Referring to FIG. 3, as explained, after the microcomputer 50 divides the memory 90 into a plurality of fixed size memory blocks according to the process shown in FIG. 2, the microcomputer 50 designates at least one of the memory blocks as the compression/decompression region. [0034] Then, the microcomputer 50 assigns the priorities of compression to rest of fixed size memory blocks except the compression/decompression region. It is determined if the memory 90 has an empty memory space for the data to be inserted. [0035] As a result of the comparison, it is known that there is no space in the memory 90 for receiving a data to be inserted therein even after all the memory blocks are compressed, the microcomputer 50 proceeds to an error processing state. Opposite to this, if there is an empty memory block or blocks as large as the data to be inserted, the data is inserted in the empty memory block or blocks of the memory 90 . [0036] Then, upon completion of insertion of the data, the microcomputer 50 compares a number of the empty memory blocks remained presently to a preset threshold value (a number of minimum memory blocks required). As a result of the comparison, if the preset threshold value is smaller than the number of empty memory blocks, the process for inserting a data is finished. [0037] Opposite to this, if the preset threshold value is greater than the number of empty memory blocks, the microcomputer 50 selects a memory block to be compressed presently from remained memory blocks according o the priorities of compression. [0038] The step for selecting the memory block to be compressed is started with reference to the compression priorities from a moment when use of a last memory block available for the data insertion is started, or the preset threshold value is exceeded. [0039] Then, the microcomputer 50 transfers the data in the memory block selected for the compression to the compression/decompression region, and compresses the data. The data in the selected memory block under compression can be accessed normally. [0040] The data in the compressed memory block is stored at other designated location of the memory 90 provided for the compressed memory block, and the compressed memory block is defined as an empty memory block by the microcomputer 50 . [0041] References representing the data in the compressed memory block are changed to a first starting address of the compressed memory block. Accordingly, when it is intended to make an indirect access to the data in the compressed memory block, the microcomputer 50 is required to determine the memory block under access presently is a compressed memory block. [0042] If it is determined that the memory block under access presently is a compressed memory block, the microcomputer 50 decompresses the compressed memory block in the compression/decompression region, and reads the decompressed memory block. [0043] [0043]FIG. 4 illustrates a flow chart showing the steps of a process for erasing a data from a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0044] Referring to FIG. 4, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2. The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns to a memory block each having a compression priority set up according to a frequency of access. [0045] The microcomputer 50 determines the data intended to erase is a data stored in the compression/decompression region. As a result of the determination, if it is determined that the data intended to erase is a data, not in the compression/decompression region, but in the memory blocks, the data is erased. [0046] Opposite to this, as a result of the determination, if it is determined that the data intended to erase is a data in the compression/decompression region, the microcomputer 50 calculates a size of memory occupied by the data to be erased in respective data blocks in the compression/decompression region. [0047] That is, if the occupied memory size is large, the microcomputer 50 determines that the memory in the block having the data erased therefrom has most of the memory left as a room space, and if the occupied memory size is small, the microcomputer 50 determines that the memory in the block having the data erased therefrom has many other data still stored in the memory block even if the data to be erased is erased. [0048] Therefore, the microcomputer 50 compares the occupied memory size in the memory block in the compression/decompression region and the threshold occupied memory size. [0049] As a result of the comparison, the occupied memory size calculated for each of the memory blocks is smaller than the threshold occupied memory size, the microcomputer 50 erases the compressed data and finishes the erasing process. Opposite to this, if the occupied memory size for each of the memory blocks is larger than the threshold occupied memory size, the microcomputer 50 decompresses the data. [0050] In this instance, referring to FIG. 4, before decompression of the compressed memory, i.e., compressed memory block, the microcomputer 50 compares a number of empty memory blocks in the memory 90 to the threshold value of empty memory blocks. Only when the number of empty memory blocks are greater than the threshold value of empty memory blocks, i.e., only when room of the memory is adequate, the microcomputer 50 decompresses the compressed data. In this instance, as explained, the data in the memory block can be accessed normally until the erasing process is finished completely. [0051] When the memory block is decompressed other memory block can also be decompressed by the microcomputer 50 . [0052] [0052]FIG. 5 illustrates a flow chart showing the steps of a process for up-dating a data stored in a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0053] Referring to FIG. 5, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2, The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns memory blocks each having a compression priority set up according to a frequency of access. [0054] The microcomputer 50 determines whether the data to be updated is stored in the compression/decompression region, or in the memory block. As a result of the determination, if it is determined that the data to be updated is stored in the memory blocks, the data is updated. [0055] As a result of the determination, if it is determined that the data to be updated is stored in the compression/decompression region, the microcomputer 50 determines a type of the data to be updated is of a variable size type or not. [0056] As a result of the determination, if the data to be updated is not the variable size type, the microcomputer 50 decompresses the compressed memory block temporarily, and updates the data to be updated. That is, when a fixed size data, with a fixed total size, is updated, the microcomputer 50 decompresses the compressed memory block, updates the data, and compresses the updated data. [0057] On the other hand, as a result of the determination, if the data to be updated is the variable size type, the microcomputer 50 assigns a new memory block and updates the data to be updated. The microcomputer 50 erases the existing data. The updating process has the inserting process explained in FIG. 3 and the erasing process explained in FIG. 4. [0058] [0058]FIG. 6 illustrates a flow chart showing the steps of a process for reading a data stored in a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0059] Referring to FIG. 6, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2. The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns to memory blocks each having a compression priority set up according to a frequency of access. [0060] The microcomputer 50 determines whether the data to be read is stored in the compression/decompression region. As a result of the determination, if it is determined that the data to be read is stored in one of the memory blocks, the microcomputer 50 reads the data. [0061] On the other hand, as a result of the determination, if the data to be read is stored in the compression/decompression region, the microcomputer decompresses the memory block having the data to be read stored therein temporarily and reads the data. [0062] As explained, the microcomputer 50 is programmed such that an access to the memory block is possible when the memory block is compressed/decompressed during the time the microcomputer 50 processes the data in the memory block, such as insertion, erasure, updating, and reading. [0063] In this instance, it is required that access to a data stored in a memory block is possible during the data is compressed/decompressed. Therefore, it is required that a final address of a compressed memory is fixed after compression of the memory block is finished completely, and the memory block under compression is valid until all the references indirectly indicating the data in the compressed memory block are revised. [0064] Opposite to this, it is also required that a compressed memory block is valid until the compressed memory block is decompressed into a general memory block, and all the references indicating the data in the general memory block is restored into original values before compression. [0065] An has been explained, the method for controlling a memory in a digital TV receiver of the present invention has the following advantages. [0066] First, the division of a data into a plurality of storage units in managing the data, and the partial compression of the data permits reduce a system performance deterioration and storage of more data when it is required to store collected data in a limited memory size. [0067] Second, the system does not come into an error state, but remains operative even if an allocated memory capacity lacks due to continuous addition of data and the like. [0068] Third, the division of a memory into fixed sized memory blocks and compression of a part of the memory blocks permits to reduce an overall data processing time period required to process entire system. [0069] It will be apparent to those skilled in the art that various modifications and variations can be made in the method for controlling a memory in a digital system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Method for controlling a memory in a digital system, including the steps of (a) dividing the memory into a plurality of fixed sized memory blocks, (b) defining at least one of the memory blocks as a compression/decompression region, (c) assigning compression priorities to rest of the memory blocks except the memory blocks defined as the compression/decompression region, and (d) making the memory blocks to deal with an external data received according to an external command, and carrying out compression/decompression of data required in the dealing with the external data at the compression/decompression region according to the compression priorities.

CROSS-REFERENCE TO RELATED APPLICATIONS The following U.S. applications were filed on Jan. 16, 1984 and assigned to the same assignees as this application: T. S. Rzeszewski 2, "Single Sideband Modulated Chrominance Information for Compatible High-Definition Definition Television", Ser. No. 571,117; and T. S. Rzeszewski 3, "Time Multiplexing Chrominance Information for Compatible High-Definition Television", Ser. No. 571,183. The following U.S. application was filed on Jan. 28, 1983, and assigned to the same assignees as this application: T. S. Rzeszewski 1, "Fully Compatible High-Definition Television", Ser. No. 462,065. TECHNICAL FIELD This invention relates to a system for improving television picture quality and particularly to encoding and decoding facilities for use in a system that provides an improved aspect ratio to specially designed receivers and a signal of usual quality to conventional receivers without alteration. BACKGROUND OF THE INVENTION Within the television (TV) industry, aspect ratio is defined to be the ratio of the width of a picture to its height. In the present United States television picture as specified by the National Television Standards Committee (NTSC), the aspect ratio is 4 to 3. A motion picture screen in a commercial theater has an aspect ratio of at least 5 to 3. Studies have shown that the present NTSC television picture aspect ratio of 4 to 3 is not desirable from a human factors point of view for certain types of production techniques. For example, the article entitled "High-Definition Wide-Screen Television System for the Future", Takashi Fujio, IEEE Transactions On Broadcasting, Vol. BC-26, No. 4, Dec. 1980, pp. 113-124, indicates that the 5 to 3 aspect ratio is desirable for a television picture. The desirability of a larger aspect ratio than the present NTSC becomes much more important when the resolution of the picture is increased. The higher resolution picture allows scenes to be displayed at a distance rather than only close up while still retaining picture detail. Since many production techniques can make advantageous use of a wider screen for displaying scenes at a distance, the need for a larger aspect ratio arises. However, it has long been recognized that the human eye tends to focus on the center of a screen and is not conscious of the edges. Hence, the same degree of resolution is not needed at the edge of a picture as required at the center. An approach to providing high-definition television that could be received as a conventional television picture by conventional television receivers operating according to the NTSC standard or that could be received as a high-definition television picture by newly designed receivers without requiring prohibitively large amounts of bandwidth is disclosed in the above-identified application of T. S. Rzeszewski 1, "Fully Compatible High-Definition Television", Ser. No. 462,065. In that system, one television channel carries the conventional information while high-frequency luminance and high-frequency chrominance information are provided in a second television channel. That system has an aspect ratio of 4 to 3. Whereas, for many applications the aspect ratio of 4 to 3 is suitable, there exist applications for which a greater aspect ratio is desirable. Therefore, there exists a need for a high-definition television system that is compatible with the standard NTSC system but that can also provide improved aspect ratio information without requiring a greater bandwidth than that provided by two television channels. SUMMARY OF THE INVENTION The foregoing problems are solved and a technical advance is achieved in accordance with the principles of this invention incorporated in an illustrative method and structural embodiment in which high-definition television picture signals with improved aspect ratio information are provided that can be received on conventional unmodified television sets and that can be received on modified receivers by the utilization of two conventional broadcast television channels. The conventional television signal is transmitted in one channel, and the other channel communicates the high-frequency luminance and chrominance information. Advantageously, the additional aspect ratio information is transmitted during the horizontal retrace interval of the other television channel relying on the conventional television channel to provide horizontal synchronization information for both television channels. Advantageously, a television receiver designed in accordance with our invention decodes the conventional luminance and chrominance information using standard techniques and is responsive to the high-frequency luminance and chrominance information in the other channel to also decode that information. In addition, that receiver is responsive to the extended aspect ratio information transmitted during the horizontal retrace interval of the other channel to gate the extended aspect ratio luminance and chrominance information from the other channel so that it can be filtered and properly translated in frequency. The receiver then combines the conventional luminance and chrominance information and the high-frequency luminance and chrominance information with the processed extended aspect ratio luminance and chrominance information for purposes of display. In addition, the extended aspect ratio chrominance information (I e Q e segments) is placed in alternate horizontal retrace intervals. Since the I e and Q e segments are alternately received, the receiver provides a storage mechanism for storing the segment received on a previous interval so that this segment can be reutilized with a present segment during the present horizontal information interval. Advantageously, the extended aspect ratio luminance and chrominance information from a high-resolution TV camera is encoded into the horizontal retrace interval of the other television channel by modulating the luminance and chrominance information before insertion into the horizontal retrace interval. The extended aspect ratio chrominance information comprises I e and Q e segments that are transmitted in alternate horizontal retrace intervals. The conventional chrominance and luminance information is encoded into a conventional television channel. The high-frequency luminance and chrominance information is encoded into the other television channel. The encoded high-frequency chrominance information is alternately transmitted during active horizontal intervals. The novel method is provided for encoding high-definition luminance and chrominance information from a high-definition video camera into conventional luminance and chrominance information communicated in a first TV channel, high-frequency chrominance and luminance information communicated in a second channel, and extended aspect ratio luminance and chrominance information communicated in the horizontal retrace interval of the second TV channel. The steps involve encoding the low-frequency luminance and chrominance information into the first TV channel, encoding the high-frequency luminance and chrominance information into the second TV channel, filtering the extended aspect ratio luminance and chrominance information from the high-definition luminance and chrominance information, gating and encoding the filtered extended aspect ratio luminance and chrominance information into the horizontal retrace interval of the second TV channel, and transmitting the first and second TV channels to TV receivers. At the receivers, the method provides for decoding the first and second channels by the following steps: decoding the low-frequency luminance and chrominance information, decoding the high-frequency luminance and chrominance information, decoding the extended aspect ratio luminance and chrominance information, and combining the decoded low-frequency luminance and chrominance information, the decoded high-frequency luminance and chrominance information, and the decoded extended aspect ratio luminance and chrominance information together for display purposes. Our invention particularly pertains to high-definition signal encoding and decoding method and apparatus illustratively embodied in video signal processing in the TV transmitter, and in TV receivers for high-definition picture display with extended aspect ratio information. BRIEF DESCRIPTION OF THE DRAWING In general, system elements, when first introduced on a figure, are each designated with a number that uses the figure number as the most significant digits of the element number. FIG. 1 shows the amplitude-frequency characteristics of the conventional baseband video signal; FIG. 2 shows the NTSC standard video wave form; FIG. 3 shows the baseband amplitude-frequency characteristics of a wideband video luminance source; FIG. 4 shows a video signal illustratively capable of providing an aspect ratio of 4.76 to 3 with a 63.5 microsecond horizontal interval; FIG. 5 illustrates the center information of FIG. 4 including synchronization and blanking signals; FIG. 6 illustrates the edge information of the video signal illustrated in FIG. 4; FIG. 7 shows the results of high-pass filtering the baseband amplitude-frequency characteristics of FIG. 3; FIG. 8 shows the two sidebands produced by modulating the signal of FIG. 7; FIG. 9 shows the composite baseband amplitude-frequency characteristics including the high-frequency chrominance and luminance information; FIGS. 10 and 11 are a block diagram of the high-definition encoder of our invention; FIG. 12 illustrates the signals generated by timing generator 1066 of FIG. 10; FIGS. 13 and 14 are a block diagram of the high-definition decoder of our invention; and FIGS. 15 and 16 show the manner in which certain of the figures should be arranged to show the specific illustrative embodiment of the invention. GENERAL DESCRIPTION The following describes a TV system that is fully compatible with conventional NTSC TV receivers and also capable of displaying high resolution and extended aspect ratio TV pictures on the system's specially designed receivers. The system uses one TV channel for carrying the conventional TV signal and a second channel for carrying the high-frequency luminance and chrominance information plus the extended aspect ratio information. During the active horizontal line time of the first TV channel, a high-definition signal from a wideband video source is separated into low-frequency and high-frequency signals. The low-frequency signal is encoded and transmitted in the first channel, and the high-frequency signal is encoded and transmitted in the second channel. During the synchronization and retrace interval of the first channel, the high-definition signal is band-limited, encoded, and transmitted in the second channel in order to provide extended aspect ratio information to the specially designed receivers. The latter are responsive to both channels to display high resolution TV pictures with extended aspect ratio information. FIG. 1 shows the nominal baseband amplitude-frequency characteristics of the video signal at the transmitter in the conventional NTSC system. The frequency of the chrominance subcarrier F sc is displaced by the 455th harmonic of half the horizontal line-scanning frequency F H from the origin. This relationship was chosen to take advantage of the fact that the luminance spectra, Y n , is actually not continuous (as shown) but exists as a multiplicity of groups of signals (not shown) centered about the harmonics of the line-scanning frequency F H . The chrominance subcarrier F sc is set at a frequency which is an odd harmonic of half the line-scanning frequency, so as to lie in a valley between two of such signal groups. The chrominance subcarrier F sc is conventionally quadrature amplitude modulated by two chroma signals designated I n and Q n in FIG. 1. The Q n chroma signal reproduces colors from the yellow-green to purple, while the I n chroma signal transmits hues ranging from bluish-green (cyan) to orange. The I n chroma signal contains both double sideband and single sideband portions (it is a vestigial sideband signal). The double sideband portion extends 0.5 megahertz (MHz) on either side of the in-phase chrominance subcarrier. The single sideband portion extends from 0.5 to 1.5 MHz below the in-phase chrominance subcarrier. The narrow band Q n chroma signal is double sideband, extending 0.5 MHz on either side of the quadrature chrominance subcarrier. The normal NTSC video signal uses a 15.7 kilohertz (kHz) scan rate resulting in 63.5 microsecond scan periods. The normal NTSC video signal allots approximately 11 microseconds (referred to as the horizontal retrace interval) in each 63.5 microsecond scan period for synchronization and blanking information resulting in 52.5 microseconds for an active video signal time. This nominal video waveform is illustrated in FIG. 2. With a 15.7 kHz line scan rate and utilizing 52.5 microseconds out of each 63.5 microsecond scan period, the NTSC video signal delivers a 4 to 3 aspect ratio picture to a conventional TV receiver. In FIG. 3, the baseband amplitude-frequency characteristic of a wideband video source having an illustrative luminance bandwidth of 7.5 MHz, adequate to provide a horizontal resolution of 600 lines, is shown. This broadened baseband source is assumed to be provided by improved camera technology which is described in greater detail with respect to FIG. 10 and 11. This improved camera technology produces a video signal, X, as illustrated in FIG. 4 that provides 62.5 microseconds of active time per each horizontal scan line at a 15.7 kHz scan rate. This video signal illustratively provides an aspect ratio of 4.76 to 3 with 1 microsecond being allowed for the active horizontal retrace interval. The format of the X signal represents the format of both the luminance information, Y, and the chrominance information, C (which comprises I and Q signals), from the improved camera. If the horizontal retrace interval can be reduced to 0.1 microsecond, the aspect ratio can be increased to 4.83 to 3, with 4.84 to 3 being the theoretical maximum as the retrace interval goes to zero. The encoder of our system proportions the X signal illustrated in FIG. 4 into a center portion, X c , as illustrated in FIG. 5 and into an edge portion, X e , as illustrated in FIG. 6. When the wideband luminance source signal, Y of FIG. 3, is presented to both a conventional (NTSC) encoder (after gating with the center signal of FIG. 12) and to a high-pass filter, the NTSC encoder accepts the lower 4.2 MHz of the 7.5 MHz luminance signal as shown in FIG. 1, and the high-pass filter, with a cutoff frequency of approximately 3 MHz communicates a luminance output, Y H , as shown in FIG. 7 of approximately 5 MHz. The luminance output Y H is delivered to a balanced modulator, advantageously of the "product" type, having a local oscillator whose frequency is set at 7/2 times the frequency of the chrominance subcarrier F sc embedded in the NTSC portion of FIG. 1. The modulator's output contains the upper and lower sideband signals shown in FIG. 8. The upper sideband of FIG. 8 is suppressed and the lower sideband is added to the conventional NTSC portion to yield the composite baseband amplitude-frequency characteristic (exclusive of the high-frequency chrominance information, C') shown in FIG. 9. As illustrated in FIG. 9 the conventional NTSC chrominance information comprising the normal NTSC chroma information (I n and Q n ) is transmitted in the conventional manner in the lower portion of FIG. 9 which is a conventional television channel. High-frequency chrominance information, C', in the form of the X c signal of FIG. 5 is also transmitted in the Y' portion of the composite baseband amplitude-frequency characteristics shown in FIG. 9. The high-frequency chrominance information, C', which consists of I' and Q' components is in the frequency spectrum between 0.5 MHz to 2 MHz as received from the high-definition TV camera. The I' and Q' signals are communicated in a time multiplexed manner. During any given active time either Q' or I' is transmitted along with the Y' signal (frequency interlaced) of FIG. 9 with the other color component being transmitted in the next active horizontal interval. The edge luminance and chrominance information in the form of the X e signal is transmitted during the 11 microsecond horizontal retrace interval of the second channel (Y' and C') illustrated in FIG. 9. This horizontal retrace interval corresponds in time to the horizontal retrace and synchronization interval of the first channel. This information can be transmitted during the horizontal retrace interval in the second channel since the horizontal sync pulse and color burst information are transmitted in the first channel as part of the standard NTSC signals. To utilize the 10 microseconds of the available 11 microseconds in the horizontal retrace interval of the second channel for transmission of the X e form signals, it is necessary to first band limit the luminance signal, Y, to 5.2 MHz and the chrominance signals, Q and I to 1.5 MHz. These signals, after being band limited, are then modulated in a similar manner in which the Y' and C' signals in the format of the X c signal were modulated before being inserted into the horizontal retrace interval of the second channel. DETAILED DESCRIPTION Referring now to FIG. 10 and 11, a block diagram of an extended aspect ratio high-definition TV encoder is described. The increased bandwidth baseband signal of FIG. 3 is provided by circuit 1000. Circuit 1000 advantageously may be of the type described in the article "Concepts for a Compatible HI-FI Television System" by B. Wendland in NTG-FACHBER, (Germany), Vol. 7, September, 1980, at pp. 407-416. That article describes an improved video source camera 1001 capable of providing an output having more than the conventional number of scanning lines. The circuit 1000 is further improved so as to provide the additional active information in a horizontal scan line as illustrated in FIG. 4. Illustratively, camera 1001 is capable of functioning as a 1050 line source of wideband red, green, and blue (R, G, B) signals. The wideband R, G, B signals from camera 1001 are then subject to the anti-aliasing filtering by circuit 1002 to remove frequency components above the Nyquist rates. Because the scanning process that changes the image into an electrical signal in the camera and then reassembles the image on the picture tube is really a sampling process, the vertical resolution is usually determined by reducing the effective number of scan lines (the total number less the number of lines in the vertical blanking interval) by a "Kell" factor of 0.6 to 0.7. Vertical filtering of the camera/source signal, however, reduces the affects of aliasing and provides a "Kell" factor approaching unity so that a vertical resolution approaching 483 lines, (525 minus (2×21)) is achieved. The point spread function (PSF) of the camera and the display are analogous to the impulse response of a linear system and are usually adjusted by shaping the electronic beam. However, a narrow PSF in the vertical direction means a wide frequency spectrum and aliasing, and a wide PSF means overlapping of adjacent lines and low-pass filtering in the vertical direction (defocusing). In the NTSC system, the PSF is adjusted to compromise between aliasing and defocusing. Anti-aliasing (prefiltering) is employed in circuit 1000 of the encoder apparatus of FIG. 10 and interpolation (postfiltering) is employed at the corresponding circuit 1350 decoder apparatus of the receiver, (FIGS. 13 and 14). In circuit 1000, the anti-alias filtered camera signals are applied by circuit 1002 to scan converter 1003. Scan converter 1003 deletes every second line of each of the 1050 line R, G, B signals to obtain a 525 line signal for ultimate transmission that is compatible with the existing (NTSC) television receivers. The wideband R, G, B signals at the output of the scan converter 1003 are applied to the R, G, B to Y, I, Q conversion matrix 1020. The output of matrix circuit 1020 takes the form of the X signal of FIG. 4. Because of the wideband input of the R, G, B signals, the luminance output Y of conversion matrix 1020 exhibits the wideband amplitude-frequency characteristics of FIG. 3. The selection of the information illustrated in FIGS. 5 and 6 from the output of matrix circuit 1020 is controlled by a center signal and an edge signal that are generated by timing generator 1066. The time relationship of the center and edge signals is illustrated in FIG. 12. When the center signal is at the "1" state, the center information illustrated in FIG. 5 is being transmitted from matrix 1020; and when the edge signal is at the "1" state, the edge information illustrated in FIG. 6 is being transmitted from matrix 1020. When the center signal is in the "1" state, the Y, I, and Q signals from matrix 1020 are processed by the NTSC encoder 1030, the Y signal by subcircuit 1101, the I signal by subcircuit 1102, and the Q signal by subcircuit 1103 to produce the two baseband signals illustrated in FIG. 9 that are transmitted after summation by adder 1071 as two conventional TV channels. Gate 1050 is responsive to the center signal to transmit the Y signal from matrix 1020 to the NTSC encoder 1030 and high-pass filter 1033. Gate 1051 is responsive to the center signal to transmit the I signal from matrix 1020 to NTSC encoder 1030 and adder circuit 1062. Correspondingly, gate circuit 1052 is responsive to the center signal to transfer the Q signal to NTSC encoder 1030 and adder circuit 1065. NTSC encoder 1030 in response to the gated Y, I, and Q signals provides conventional luminance and chrominance output signals, Y n +C n , to adder 1071. In the absence of any other input, the output of adder 1071 would simply be a conventional NTSC baseband signal communicated to the final video modulator stage (not shown) that would radiate a signal to a designated TV channel according to the frequency of the video carrier selected. However, adder 1071 receives additional inputs C', C' e , Y', and Y' e , to be described, and the latter are transmitted by the final modulator stage (not shown) in the second of two designated TV channels. These channels should preferably be adjacent channels to minimize the affects of weather, however, more widely separated channels may also be employed. The high-frequency, gated portion of the Y signal from 1020 is modulated and transmitted to adder 1071 by blocks 1033, 1032, 1061, 1034 and 1053. Oscillator 1031 receives the chrominance subcarrier F sc from encoder 1030 and serves as a local oscillator for modulator 1032. The frequency of the local oscillator's output is advantageously chosen to be 7/2 the frequency of the chrominance subcarrier F sc . In the NTSC system, where the baseband chrominance subcarrier is 455×F H /2, the local oscillator frequency, F c , provided by oscillator 1031 to modulator 1032 is approximately 12.53 MHz. The other signal that is received by modulator 1032 is the upper portion of the wideband luminance signal, Y H , which is received from the output of gate 1050 during the active time of the center signal. The output of gate 1050 is first filtered by high-pass filter 1033. Filter 1033 is advantageously chosen to have a crossover frequency of approximately 3 MHz. In response to these two inputs, the output of modulator 1032 contains the two sideband signals shown in FIG. 8. The upper sideband signal is suppressed by bandpass filter 1034, and the lower sideband signal of Y' is communicated to adder 1071. Before the Y' signal is communicated to filter 1034, it must be communicated through gate circuit 1053 and summation circuit 1061. The purpose of summation circuit 1061 is to allow the luminance signal to consist of either Y' or Y e depending upon whether the center or edge signal is presently active. The center signal controls gate 1053 to gate the Y' signal to summation circuit 1061 at the proper time, and summation circuit 1061 then communicates the signal to filter 1034. The latter suppresses the upper sideband signal and communicates the lower sideband signal to adder 1071. During the center time, adder 1071 combines signals Y n and C n from NTSC encoder 1030 with the wideband luminance signal Y' from filter 1034 to yield a baseband output signal having the baseband amplitude-frequency characteristics (with the exception of C') of FIG. 9. This baseband amplitude-frequency characteristic is capable of providing a high definition image within a signal spectrum requiring not more than two conventional (6 MHz) video channels. The definition of the high-frequency chrominance components of the video signal during the center time is also enhanced in the following manner. The gated I and Q signals from matrix 1020 are delivered via summation circuits 1062 and 1065 to filters 1043 and 1044, respectively, which limit each chrominance component to a 1.5 MHz bandwidth extending from 0.5 to 2.0 MHz. These signals are delivered to bandpass filters 1043 and 1044 during the center time by gates 1051 and 1052 responding to the I and Q signals, respectively, from matrix 1020 and gating the signals to summation circuits 1062 and 1065. The band limited outputs of filter 1043 and 1044 are alternately gated at half the normal line rate (F H /2) by color multiplexor 1070 under control of the line selection circuit 1085. Line selection circuit 1085 receives the composite sync signal from NTSC encoder 1030 and controls multiplexor 1070, by counting the sync pulses, so that each new field starts its first line from the I signal output of filter 1043. The chrominance components I and Q are alternately selected by multiplexor 1070 and are applied to product modulator 1045. The frequency of local oscillator 1047 F o , that is applied to the product modulator 1045 is chosen so that the chrominance output spectra of the modulator interleave, without interference, with the high-frequency luminance spectra of the signals from band-pass filter 1034. Since multiplexor 1070 samples the chrominance components at half the horizontal line rate, the multiplexor's output spectra is naturally grouped at multiples of half the line rate. To avoid this interference with the high-frequency luminance spectra, the local oscillator frequency, F o , as applied to the product modulator 1045 is proportioned according to the formula F o =288 F H which is approximately 4.53 MHz. The high-frequency multiplex chrominance components at the output of modulator 1045 are applied to band-pass filter 1046 to eliminate the upper sideband. The upper sideband output, C', of filter 1046 is applied to one input of adder 1071. Since the other inputs of adder 1071 during the center time period are the conventional NTSC baseband signal and the high-frequency luminance signal, Y', the output of adder 1071 provides the composite baseband signal of FIG. 9 including C'. The edge luminance and chrominance information from matrix 1020 is inserted into the second television channel during the horizontal retrace interval in the following manner. The luminance information, Y, from matrix 1020 is received by low-pass filter 1068 that limits the bandwidth to 5.2 MHz. During the edge time, gate 1054 is responsive to the edge signal from timing generator 1066 to communicate the band limited Y signal from filter 1068 to product modulator 1161. Modulator 1161 translates the band limited Y signal into the proper frequency range of the second channel. The other input to modulator 1161 is a 10.1 MHz signal (a multiple of F H ) from oscillator 1060. The output of modulator 1161 is a double sideband suppressed carrier signal which is communicated to band-pass filter 1034 by summation circuit 1061. The upper sideband is eliminated or made into a vestigal sideband signal by band-pass filter 1034 resulting in the Y' e signal that is communicated by band-pass filter 1034 to adder 1071. The Y' e signal occupies the same position in the spectrum during the horizontal retrace interval as is occupied by the Y' signal during the center time. During each horizontal scan period, Y' is present during the center time (duration of 52.5 microseconds) and the Y' e signal is present during the edge time (duration of 10 microseconds). The chrominance edge information is communicated to the television receiver in the following manner. The I and Q signal from matrix 1020 are first communicated to low-pass filters 1042 and 1041, respectively, in order to band limit the I and the Q signals. The gates 1055 and 1056 produce the band limited chroma signals during only the edge time. These two signals are translated in frequency by modulating with a 2 MHz carrier (a multiple of F H )to produce two double sideband signals that are then passed through 0.5 to 2.0 MHz band-pass filters to suppress the upper sideband signals. The two resulting signals are then alternately selected by multiplexor 1070 and modulated and filtered by circuits 1045 and 1046, respectively, as was previously described for the I' and Q' signals. Describing this process now in greater detail, the output of low-pass filter 1042 is gated to modulator 1063 during the edge time by gate 1055 responding to the edge signal from timing generator 1066. Modulator 1063 is responsive to the I signal to output a double sideband signal to adder 1062 which transfers it and the center gated I signal to band-pass filter 1043. Filter 1043 suppresses the upper sideband of the signal and makes a resulting single sideband representation of the I e signal available to multiplexor 1070. Blocks 1041, 1056, 1064, 1048, 1065 and 1044 process the Q signal in the same manner as previously described for the I signal to produce a similar Q e edge signal. Multiplexor 1070 responds to these signals in the identical manner as previously described for the I' and Q' signals to produce a C e signal during the edge time which alternately contains the I e or Q e signals. Modulator 1045 is responsive to the output of multiplexor 1070 to produce C' e that alternately contains I' and Q' e . Adder 1071 is continuously responsive to the Y', Y' e , C', C' e , Y n and C n signals to produce the Z signal as illustrated in FIG. 9 (with Y' e and C' e added to Y' and C', respectively) which is then modulated and transmitted over conventional video channels. A decoder for receiving the signal shown in FIG. 9 is illustrated in FIG. 13. Radio frequency (RF) tuner, video detector, and intermediate frequency (IF) stage 1301 receives the incoming TV signal, i.e., the two TV channels containing the broadband luminance and chrominance information heretofore described. Accordingly, stage 1301 may contain either a broadband RF tuner capable of receiving two adjacent TV channels or separate RF tuners each tuned to a respective channel. In either event, the output of stage 1301 provides the baseband amplitude-frequency characteristic of FIG. 9 with Y' e and C' e added to Y' and C', respectively. Stage 1301 is coupled at its output to circuits 1360, 1340, 1302, 1312, and 1361. The low-frequency luminance information, Y L , is recovered by low-pass filter 1360 whose output is communicated to sum circuit 1374. The high-frequency luminance signal, Y H , is recovered by blocks 1340, 1366, 1341, and 1331 during the center time. The Y H and Y L signals are combined by sum circuit 1374 and the result is gated to sum circuit 1372 at the center time by gate 1375 in response to the center signal from block 1303. The Y' signal is recovered from the output of stage 1301 by band-pass filter 1340 limiting the Y signal to a region from 4.9 to 10.1 MHz and comb filter 1366 removing the C' signal. Modulator 1341 and filter 1331 are responsive to the output of comb filter 1366 to deliver a lower sideband signal, 2.5 to 7.5 MHz, containing the Y' information. Modulator 1341 receives a local oscillator input from oscillator 1367 that is 7/2 times the frequency of the color subcarrier F sc as detected by the NTSC decoder 1302. The other input to modulator 1341 is the upper portion of the baseband video signal (Y) in the center of the image extending from approximately 4.9 to 10.1 MHz as shown in FIG. 9 as Y' and separated by band-pass filter 1340 and comb filter 1366. The output of filter 1331 contains the translated Y H signal and is communicated to sum circuit 1374. Gate 1375 communicates the Y L and the translated Y H to sum circuit 1372 only during the center time in response to the center signal from frequency synthesizer 1303. The luminance information contained in the edge luminance signal, Y' e , is recovered from the output of stage 1301 by the blocks 1340, 1366, 1368, and 1370. Filters 1340 and 1366 filter the Y' e signal received from stage 1301 in the same manner as was previously described for the Y' signal. The Y' e signal is then translated down to baseband frequency by modulator 1368 that multiplies the Y' e signal with a carrier at approximately 10.1 MHz that is derived by oscillator 1369. Low-pass filter 1370 retains only the baseband portion of the output of modulator 1368. The output of low-pass filter 1370, which is Y e , is gated at the edge time to sum circuit 1372 by gate 1371 in response to the edge signal. The output of sum circuit 1372 is the combination of Y L plus the translated Y H during the center time and the Y e signal during the edge time so that adder 1307 is constantly receiving a luminance signal (Y) from sum circuit 1372. The chrominance information is recovered from the output of stage 1301 in the following manner. NTSC decoder 1302 receives the broadband signal of FIG. 9 with Y' e and C' e included from stage 1301 and at its output provides the low frequency Q n and I n , chrominance signals (band limited to 0.5 MHz) designated Q L and I L , to adders 1304 and 1305, respectively. Adders 1304 and 1305 combine the Q L and I L signals with high frequency chrominance signals (Q H and I H translated and center gated) and edge chrominance signals (Q e and I e translated and edge gated) that are recovered from the output of stage 1301 by subcircuit 1320. Subcircuit 1320 demodulates the high frequency chrominance signals, I' and Q' from the output of 1301 in the following manner. The I' and Q' signals are being transmitted on alternate horizontal lines in the upper 6 MHz band by a distant television transmitter. Band-pass filter 1361 is responsive to the output of stage 1301 to limit the signals to the region of 5.0 to 6.5 MHz in which the high frequency and edge chrominance signals are transmitted as shown in the baseband signal of FIG. 9. The comb filter 1362 removes the Y' and Y' e signals before transmitting the chrominance information to modulator 1363. Modulator 1363 provides a frequency translation function by modulating the chrominance information into the proper chrominance band of 0.5 to 2.0 MHz. The modulator also translates the chrominance information up to the 2F o range but this is removed by filter 1365. The output of filter 1365 is the C H signal which alternately comprises I H and Q H signals. Since the I' and Q' signals are being alternately transmitted, it is necessary to store one signal from a previous line and reuse it on the present line in order to obtain the desired information. Delay line circuit 1386 performs this storage function. Multiplexor 1373 is responsive to the output of frequency synthesizer 1303 to alternate between the output of bandpass filter 1365 and delay line 1386 so that the information for the Q H and I H signals is continuous from multiplexor 1373. The translated Q H and I H signals from multiplexor 1373 are communicated by gates 1387 and 1388 in response to the center signal from frequency synthesizer 1303 during the center time to sum circuits 1398 and 1399, respectively. During the center time, sum circuits 1398 and 1399 communicate the translated and gated Q H and I H signals to adders 1304 and 1305, respectively. The Q L signal and the translated and gated Q H signal are combined by adder 1304, similarly the I L signal and the translated and gated I H signal are combined by adder 1305 before transmission to matrix circuit 1306. The edge chrominance information is handled in a similar manner as the chrominance high-frequency information by subcircuit 1320 with the following exception. The chrominance edge information occupies a bandwidth of 0 to 1.5 MHz and in order to recover this information from the output of multiplexor 1373, it is necessary to frequency translate the outputs of multiplexor 1373 by 2 MHz. The modulators 1390 and 1393 generate both the baseband edge signals and components translated up by 4 MHz. The upper portion of these signals are then eliminated by low-pass filters leaving only the baseband signals that occupy the region from 0 to 1.5 MHz and contain the edge chrominance information. These operations are performed by blocks 1390 through 1395. The resulting outputs of low-pass filters 1392 and 1395 contain the baseband versions of I e and Q e , respectively, and only need to be gated with the edge signal controlling gates 1396 and 1397, respectively, to produce the desired edge chrominance information. The translated and gate Q e signal is communicated by gate 1396 to sum circuit 1398 and the translated and gated Q H signal is communicated by gate 1387 to sum circuit 1398 at the appropriate times. Sum circuit 1398 combines the translated and gated Q e and Q H signals before transmission to adder 1304. Similarly, the translated and gated I H and I e signals are combined by sum circuit 1399 before transmission to adder circuit 1305. The translated Q H and I H signals are transmitted during the center time to adders 1304 and 1305, respectively, while the translated Q e and I e signals are transmitted during the edge time to adders 1304 and 1305, respectively. In turn, adders 1304 and 1305 communicate the I and Q signals to matrix circuit 1306. Matrix circuit 1306 combines the I and Q signals outputted by adders 1305 and 1304, respectively, to produce the R-Y, G-Y, B-Y, signals that are transmitted to adder 1306. Adder 1307, in response to the outputs of adder 1372 and the matrix circuit 1306, produces the R, G, and B signals that are then used to display the video picture by subcircuit 1350. While the illustrative embodiments of our invention have been described specifically with relation to NTSC standards and protocols, it is to be understood that the principles of our invention are applicable to other standards and protocols, such as PAL. Furthermore, these circuits and amplitude-characteristics which have been described are deemed to be illustrative of the principles of our invention. Numerous modifications may be made by those skilled in the art without departing from the spirit and scope of our invention.

A television system having a fully compatible high-definition signal with extended aspect ratio information receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with one TV channel carrying the conventional TV signal while high-frequency luminance and chrominance information plus extended aspect ratio information are provided in a second TV channel. The extended aspect ratio information including luminance and chrominance information is transmitted during the horizontal retrace interval of the second TV channel. The extended aspect ratio chrominance information comprises I e and Q e segments which are transmitted during alternate horizontal retrace intervals. Since the segments are alternately transmitted, a storage mechanism is provided so that a segment received during a previous horizontal retrace interval can be reused during the present horizontal retrace interval for displaying the complete chrominance edge information.

BACKGROUND [0001] Technical Field [0002] This present disclosure generally relates to electronic commerce software applications and, more particularly, to evaluating prices and transactions for purchasing. [0003] Description of the Related Art [0004] Commodity items such as lumber, agricultural products, metals, and livestock/meat are usually traded in the open market between a number of buyers and sellers. The sales transactions of most commodity items involve a number of parameters. For instance, in the trade of commodity lumber, a buyer usually orders materials by specifying parameters such as lumber species, grade, size (i.e., 2×4, 2×10, etc.), and length, as well as the “tally” or mix of units of various lengths within the shipment, method of transportation (i.e., rail or truck), shipping terms (i.e., FOB or delivered), and desired date of receipt, with each parameter influencing the value of the commodity purchase. Given the multiple possible combinations of factors, a commodity buyer often finds it difficult to objectively compare similar but unequal offerings among competing vendors. [0005] For example, in a case where a lumber buyer desires to order a railcar load of spruce (SPF) 2×4's of #2 & Better grade, the buyer would query vendors offering matching species and grade carloads seeking the best match for the buyer's need or tally preference at the lowest market price. Lumber carloads are quoted at a price per thousand board feet for all material on the railcar. When the quoted parameters are not identical, it is very difficult for buyers to determine the comparative value of unequal offerings. [0006] Typically, a lumber buyer will find multiple vendors each having different offerings available. For example, a railcar of SPF 2×4's may be quoted at a rate of $300/MBF (thousand board feet) by multiple vendors. Even though the MBF price is equal, one vendor's carload may represent significantly greater marketplace value because it contains the more desirable lengths of 2×4's, such as market-preferred 16-foot 2×4's. When the offering price varies in addition to the mix of lengths, it becomes increasingly difficult to compare quotes from various vendors. Further, because construction projects often require long lead times, the lumber product may need to be priced now, but not delivered until a time in the future. Alternately, another species of lumber (i.e., southern pine) may represent an acceptable substitute. [0007] Therefore, from the foregoing, there is a need for a method and system that allows buyers to evaluate the price of commodity offerings possessing varying shipping parameters. BRIEF SUMMARY [0008] The present disclosure describes a system that operates in a networked environment. The system comprises at least one server that includes a network interface, a non-transitory computer-readable medium, and a processor in communication with the network interface and the computer-readable medium. The computer-readable medium has computer-executable instructions stored thereon that, when executed, implement components including at least a metric server adapter and a metrics application. The processor is configured to execute the computer-executable instructions stored in the computer-readable medium. [0009] In various embodiments, the metric server adapter includes governing logic programmed to manage at least one evaluation service and a plurality of predefined instructions that pertain to the evaluation service and/or data used to provide the at least one evaluation service. The metrics application includes one or more production applications or modules programmed to manage one or more purchase and/or analysis processes, to execute the evaluation service in coordination with the metric server adapter. The metrics application also manages one or more user interfaces that, in operation, facilitate interactions with the server. [0010] In operation, the server is configured to receive a plurality of price data sets from at least one computing device in communication with the server, or retrieve a plurality of price data sets from at least one data source accessible to the server. Each price data set comprises an offer to buy or sell that identifies price data for at least one item possessing a plurality of attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0011] In response to receipt or retrieval of at least one price data set, the server implements the evaluation service which causes the metrics application, for each price data set, to obtain time-dependent metric data from at least one data source accessible to the server. The obtained metric data includes market reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set. Each responsive item in the metric data possesses a plurality of attributes that include at least one parameter value. [0012] The metrics application evaluates the plurality of attributes of each responsive item in the metric data relative to the attributes for the respective item identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the metric server adapter which enables the metric server adapter to define offer-specific instructions for adapting the metric data for the respective item. [0013] The metrics application normalizes the metric data by executing the offer-specific instructions for adapting the metric data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0014] The metrics application generates at least one comparative metric that pertains to the at least one evaluation service. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in a price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. [0015] Also disclosed herein, in various embodiments, is a method for evaluating unequal offers in a networked environment. The method includes receiving, at at least one server, a plurality of price data sets. The server operates under control of computer-executable instructions that, when executed by a processor, implement components including at least a governing logic component and a production component. Each price data set comprises an offer to buy or sell that identifies price data for at least one item possessing attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0016] For each received price data set, the method further comprises implementing, by the server, at least one evaluation service. In operation, the evaluation service includes obtaining, by the production component, time-dependent market-reference data from at least one data source accessible to the server. The market reference data includes market-reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set, wherein each responsive item possesses a plurality of attributes including at least one parameter value. [0017] The evaluation service further includes evaluating, by the production component, the plurality of attributes of each responsive item in the market reference data relative to the plurality of attributes for the respective item as identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the governing logic component which enables the governing logic component to define offer-specific instructions for adapting the market reference data for the respective item. [0018] The market reference data is normalized, wherein the production component executes the offer-specific instructions for adapting the market reference data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0019] At least one comparative metric that pertains to the evaluation service is generated by the production component. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in the price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. [0020] Further disclosed herein is a non-transitory computer-readable medium having computer-executable instructions stored thereon. The computer-executable instructions, when executed, cause at least one server in a networked environment to perform operations that include receiving, at the server, a plurality of price data sets. The server operates under control of the computer-executable instructions that, when executed by a processor, implement components including a governing logic component and a production component. [0021] Each price data set includes price data and represents an offer to buy or sell at least one identified item possessing attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0022] Implementing at least one evaluation service, for each received price data set, the computer-executable instructions cause the server to obtain, by the production component, time-dependent market-reference data from at least one data source accessible to the server. The market reference data includes market-reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set. Each responsive item in the market-reference data possesses a plurality of attributes including at least one parameter value. [0023] The production component evaluates the plurality of attributes of each responsive item in the market reference data relative to the plurality of attributes for the respective item as identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the governing logic component which enables the governing logic component to define offer-specific instructions for adapting the market reference data for the respective item. [0024] The production component normalizes the market reference data, wherein the production component executes the offer-specific instructions for adapting the market reference data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0025] The production component generates at least one comparative metric that pertains to the at least one evaluation service. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in the price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0026] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: [0027] FIG. 1 is a block diagram of a prior art representative portion of the Internet; [0028] FIG. 2 is a pictorial diagram of a system of devices connected to the Internet, which depict the travel route of data; [0029] FIG. 3 is a block diagram of the several components of the buyer's computer shown in FIG. 2 that is used to request information on a particular route; [0030] FIG. 4 is a block diagram of the several components of an information server shown in FIG. 2 that is used to supply information on a particular route; [0031] FIG. 5 is a flow diagram illustrating the logic of a routine used by the information server to receive and process the buyer's actions; [0032] FIGS. 6A-6B are flow diagrams illustrating another embodiment of the logic used by the information server to receive and process the quotes and quote requests of both buyers and vendors; [0033] FIG. 7 is a flow diagram illustrating another embodiment of the logic used by the information server to execute the process of a catalog purchase; [0034] FIGS. 8A-8D are images of windows produced by a Web browser application installed on a client computer accessing a server illustrating one embodiment of the present disclosure; and [0035] FIG. 9 is a flow diagram illustrating one embodiment of the normalization process described herein. DETAILED DESCRIPTION [0036] The term “Internet” refers to the collection of networks and routers that use the Internet Protocol (IP) to communicate with one another. A representative section of the Internet 100 as known in the prior art is shown in FIG. 1 in which a plurality of local area networks (LANs) 120 and a wide area network (WAN) 110 are interconnected by routers 125 . The routers 125 are generally special-purpose computers used to interface one LAN or WAN to another. Communication links within the LANs may be twisted wire pair, or coaxial cable, while communication links between networks may utilize 56 Kbps analog telephone lines, or 1 Mbps digital T-1 lines, and/or 45 Mbps T-3 lines. Further, computers and other related electronic devices can be remotely connected to either the LANs 120 or the WAN 110 via a modem and temporary telephone link. Such computers and electronic devices 130 are shown in FIG. 1 as connected to one of the LANs 120 via dotted lines. It will be appreciated that the Internet comprises a vast number of such interconnected networks, computers, and routers and that only a small representative section of the Internet 100 is shown in FIG. 1 . [0037] The World Wide Web (WWW), on the other hand, is a vast collection of interconnected, electronically stored information located on servers connected throughout the Internet 100 . Many companies are now providing services and access to their content over the Internet 100 using the WWW. In accordance with the present disclosure, and as shown in FIG. 2 , there may be a plurality of buyers operating a plurality of client computing devices 235 . FIG. 2 generally shows a system 200 of computers and devices to which an information server 230 is connected and to which the buyers' computers 235 are also connected. Also connected to the Internet 100 is a plurality of computing devices 250 associated with a plurality of sellers. The system 200 also includes a communications program, referred to as CEA, which is used on the sellers' computing devices 250 to create a communication means between the sellers' backend office software and the server applications. [0038] The buyers of a market commodity may, through their computers 235 , request information about a plurality of items or order over the Internet 100 via a Web browser installed on the buyers' computers. Responsive to such requests, the information server 230 , also referred to as a server 230 , may combine the first buyer's information with information from other buyers on other computing devices 235 . The server 230 then transmits the combined buyer data to the respective computing devices 250 associated with the plurality of sellers. Details of this process are described in more detail below in association with FIGS. 5-7 . [0039] Those of ordinary skill in the art will appreciate that in other embodiments of the present disclosure, the capabilities of the server 230 and/or the client computing devices 235 and 250 may all be embodied in the other configurations. Consequently, it would be appreciated that in these embodiments, the server 230 could be located on any computing device associated with the buyers' or sellers' computing devices. Additionally, those of ordinary skill in the art will recognize that while only four buyer computing devices 235 , four seller computing devices 250 , and one server 230 are depicted in FIG. 2 , numerous configurations involving a vast number of buyer and seller computing devices and a plurality of servers 230 , equipped with the hardware and software components described below, may be connected to the Internet 100 . [0040] FIG. 3 depicts several of the key components of the buyer's client computing device 235 . As known in the art, client computing devices 235 are also referred to as “clients” or “devices,” and client computing devices 235 also include other devices such as palm computing devices, cellular telephones, or other like forms of electronics. A client computing device can also be the same computing device as the server 230 . An “agent” can be a person, server, or a client computing device 235 having software configured to assist the buyer in making purchasing decisions based on one or more buyer-determined parameters. Those of ordinary skill in the art will appreciate that the buyer's computer 235 in actual practice will include many more components than those shown in FIG. 3 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 3 , the buyer's computer includes a network interface 315 for connecting to the Internet 100 . Those of ordinary skill in the art will appreciate that the network interface 315 includes the necessary circuitry for such a connection and is also constructed for use with TCP/IP protocol. [0041] The buyer's computer 235 also includes a processing unit 305 , a display 310 , and a memory 300 , all interconnected along with the network interface 315 via a bus 360 . The memory 300 generally comprises a random access memory (RAM), a read-only memory (ROM), and a permanent mass storage device, such as a disk drive. The memory 300 stores the program code necessary for requesting and/or depicting a desired route over the Internet 100 in accordance with the present disclosure. More specifically, the memory 300 stores a Web browser 330 , such as Netscape's NAVIGATOR® or Microsoft's INTERNET EXPLORER® browsers, used in accordance with the present disclosure for depicting a desired route over the Internet 100 . In addition, memory 300 also stores an operating system 320 and a communications application 325 . It will be appreciated that these software components may be stored on a computer-readable medium and loaded into memory 300 of the buyers' computer 235 using a drive mechanism associated with the computer-readable medium, such as a floppy, tape, or CD-ROM drive. [0042] As will be described in more detail below, the user interface which allows products to be ordered by the buyers are supplied by a remote server, i.e., the information server 230 located elsewhere on the Internet, as illustrated in FIG. 2 . FIG. 4 depicts several of the key components of the information server 230 . Those of ordinary skill in the art will appreciate that the information server 230 includes many more components than shown in FIG. 4 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 4 , the information server 230 is connected to the Internet 100 via a network interface 410 . Those of ordinary skill in the art will appreciate that the network interface 410 includes the necessary circuitry for connecting the information server 230 to the Internet 100 , and is constructed for use with TCP/IP protocol. [0043] The information server 230 also includes a processing unit 415 , a display 440 , and a mass memory 450 , all interconnected along with the network interface 410 via a bus 460 . The mass memory 450 generally comprises a random access memory (RAM), read-only memory (ROM), and a permanent mass storage device, such as a hard disk drive, tape drive, optical drive, floppy disk drive, or combination thereof. The mass memory 450 stores the program code and data necessary for incident and route analysis as well as supplying the results of that analysis to consumers in accordance with the present disclosure. More specifically, the mass memory 450 stores a metrics application 425 formed in accordance with the present disclosure for managing the purchase forums of commodities products, and a metric server adapter 435 for managing metric data. In addition, mass memory 450 stores a database 445 of buyer information continuously logged by the information server 230 for statistical market analysis. It will be appreciated by those of ordinary skill in the art that the database 445 of product and buyer information may also be stored on other servers or storage devices connected to either the information server 230 or the Internet 100 . Finally, mass memory 450 stores Web server software 430 for handling requests for stored information received via the Internet 100 and the WWW, and an operating system 420 . It will be appreciated that the aforementioned software components may be stored on a computer-readable medium and loaded into mass memory 450 of the information server 230 using a drive mechanism associated with the computer-readable medium, such as floppy, tape, or CD-ROM drive. In addition, the data stored in the mass memory 450 and other memory can be “exposed” to other computers or persons for purposes of communicating data. Thus, “exposing” data from a computing device could mean transmitting data to another device or person, transferring XML data packets, transferring data within the same computer, or other like forms of data communications. [0044] In accordance with one embodiment of the present disclosure, FIG. 5 is a flow chart illustrating the logic implemented for the creation of a Request for Quote (RFQ) by a singular buyer or a pool of buyers. In process of FIG. 5 , also referred to as the pooling process 500 , a buyer or a pool of buyers generate an RFQ which is displayed or transmitted to a plurality of sellers. Responsive to receiving the RFQ, the sellers then send quotes to the buyers. [0045] In summary, the creation of the RFQ consists of at least one buyer initially entering general user identification information to initiate the process. The buyer would then define a Line Item on a Web page displaying an RFQ form. The Line Item is defined per industry specification and units of product are grouped as a “tally” per industry practice. The pooling process 500 allows buyers to combine RFQ Line Items with other buyers with like needs. In one embodiment, the pool buy feature is created by a graphical user interface where the RFQ Line Items from a plurality of buyers are displayed on a Web page to one of the pool buyers, referred to as the pool administrator. The server 230 also provides a Web-based feature allowing the pool administrator to selectively add each RFQ Line Item to one combined RFQ. The combined RFQ is then sent to at least one vendor or seller. This feature provides a forum for pooling the orders of many buyers, which allows individual entities or divisions of larger companies to advantageously bid for larger orders, thus providing them with more bidding power and the possibility of gaining a lower price. [0046] The pooling process 500 begins in step 501 where a buyer initiates the process by providing buyer purchase data. In step 501 , the buyer accesses a Web page transmitted from the server 230 configured to receive the buyer purchase data, also referred to as the product specification data set or the Line Item data. One exemplary Web page for the logic of step 501 is depicted in FIG. 8A . As shown in FIG. 8A , the buyer enters the Line Item data specifications in the fields of the Web page. The Line Item data consists of lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , delivery location 808 , and the overall quantity 809 . In one embodiment, the buyer must define the delivery date as either contemporaneous “on-or-before” delivery date or specify a delivery date in the future for a “Forward Price” RFQ. In addition, the buyer selects a metric or multiple metrics in a field 810 per RFQ Line Item (tally). As described in more detail below, the metric provides pricing data that is used as a reference point for the buyer to compare the various quotes returned from the sellers. The buyer RFQ Line Item data is then stored in the memory of the server 230 . [0047] Returning to FIG. 5 , at a next step 503 , the server 230 determines if the buyer is going to participate in a pool buy. In the process of decision block 503 , the server 230 provides an option in a Web page that allows the buyer to post their Line Item data to a vendor or post their Line Item data to a buyer pool. The window illustrated in FIG. 8A is one exemplary Web page illustrating these options for a buyer. As shown in FIG. 8A , the links “Post Buyer Pool” 812 and “Post to Vendors” 814 are provided on the RFQ Web page. [0048] At step 503 , if the buyer does not elect to participate in a pool buy, the process continues to step 513 where the server 230 generates a request for a quote (RFQ) from the buyer's Line Item data. A detailed description of how the server 230 generates a request for a quote (RFQ) is summarized below and referred to as the purchase order process 600 A depicted in FIG. 6A . [0049] Alternatively, at decision block 503 , if the buyer elects to participate in a pool buy, the process continues to step 505 where the system notifies other buyers logged into the server 230 that an RFQ is available in a pool, allowing other buyers to add additional Line Items (tallies) to the RFQ. In this part of the process, the Line Items from each buyer are received by and stored in the server memory. The Line Items provided by each buyer in the pool are received by the server 230 using the same process as described above with reference to block 501 and the Web page of FIG. 8A . All of the Line Items stored on the server 230 are then displayed to a pool administrator via a Web page or an e-mail message. In one embodiment, the pool administrator is one of the buyers in a pool where the pool administrator has the capability to select all of the Line Item data to generate a combined RFQ. The server 230 provides the pool administrator with this capability by the use of any Web-based communicative device, such as e-mail or HTML forms. As part of the process, as shown in steps 507 and 509 , the pool may be left open for a predetermined period of time to allow additional buyers to add purchase data to the current RFQ. [0050] At decision block 509 , the server 230 determines if the pool administrator has closed the pool. The logic of this step 509 is executed when the server 230 receives the combined RFQ data from the pool administrator. The pool administrator can send the combined RFQ data to the server 230 via an HTML form or by other electronic messaging means such as e-mail or URL strings. Once the server 230 has determined that the pool is closed, the process continues to block 510 where the Line Items from each buyer (the combined RFQ) are sent to all of the buyers in the pool. The process then continues to step 513 where the server 230 sends the combined RFQ to the vendors or sellers. [0051] Referring now to FIG. 6A , one embodiment of the purchase-negotiation process 600 is disclosed. The purchase-negotiation process 600 is also referred to as a solicited offer process or the market purchase process. In summary, the purchase-negotiation process 600 allows at least one buyer to submit an RFQ and then view quotes from a plurality of vendors and purchase items from selected vendor(s). The logic of FIG. 6A provides buyers with a forum that automatically manages, collects, and normalizes the price of desired commodity items. The purchase-negotiation process 600 calculates a normalized price data set that is based on a predefined metric(s). The calculation of the normalized price data set in combination with the format of the Web pages described herein create an integrated forum where quotes for a plurality of inherently dissimilar products can be easily obtained and compared. [0052] The purchase-negotiation process 600 begins at step 601 where the RFQ, as generated by one buyer or a pool of buyers in the process depicted in FIG. 5 , is sent to a plurality of computing devices 250 associated with a plurality of sellers or vendors. The vendors receive the RFQ via a Web page transmitted by the server 230 . In one embodiment, the vendors receive an e-mail message having a hypertext link to the RFQ Web page to provide notice to the vendor. Responsive to the information in the buyers' RFQ, the process then continues to step 603 where at least one vendor sends their quote information to the server 230 . [0053] In the process of step 603 , the vendors respond to the RFQ by sending their price quote to the server 230 for display via a Web page to the buyer or buyer pool. Generally described, the vendors send an HTML form or an e-mail message with a price and description of the order. The description of the order in the quote message contains the same order information as the RFQ. [0054] FIG. 8B illustrates one exemplary Web page of a vendor quote that is displayed to the buyer. As shown in FIG. 8B , the vendor quote includes the vendor's price 813 , the lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , and delivery location 808 . In the quote response message, the vendor has the capability to modify any of the information that was submitted in the RFQ. For example, the vendor may edit the quantity values for the various units comprising the preferred assortment in the tally 805 A-E. This allows the vendor to adjust the buyer's request according to the vendor's inventory, best means of transportation, etc. All of the vendor's quote information is referred to as price data set or the RFQ Line Item (tally) quote. [0055] Returning to FIG. 6A , the process continues to step 605 , where the server 230 normalizes the price of each RFQ Line Item (tally) quote from each vendor. The normalization of the vendor's price is a computation that evaluates the vendor's price utilizing data from a metric. The normalization process is carried out because each vendor may respond to the Line Items of an RFQ by quoting products that are different from a buyer's RFQ and/or have a different tally configuration. The normalization of the pricing allows the buyers to objectively compare the relative value of the different products offered by the plurality of vendors. For example, one vendor may produce a quote for an RFQ of one unit of 2×4×10, two units of 2×4×12, and three units of 2×4×16. At the same time, another vendor may submit a quote for three units of 2×4×10, one unit of 2×4×12, and two units of 2×4×16. Even though there is some difference between these two offerings, the price normalization process provides a means for the buyer to effectively compare and evaluate the different quotes even though there are variations in the products. The price normalization process 900 is described in more detail below in conjunction with the flow diagram of FIG. 9 . [0056] Returning again to FIG. 6A , at step 607 the vendor's quote information is communicated to the buyer's computer for display. As shown in FIG. 8B and described in detail above, the vendor's quote is displayed via a Web page that communicates the vendor's quote price 813 and other purchase information. In addition, the vendor's quote page contains a metric price 815 and a quote price versus metric price ratio 816 . The metric price 815 and the quote price versus metric price ratio 816 are also referred to as a normalized price data value. A ratio higher than one (1) indicates a quote price that is above the metric price, and a lower ratio indicates a quote price that is below the metric price. [0057] Next, at step 609 , the buyer or the administrator of the buyer pool compares the various products and prices quoted by the vendors along with the normalized price for each Line Item on the RFQ. In this part of the process, the buyer may decide to purchase one of the products from a particular vendor and sends a notification to the selected vendor indicating the same. The buyer notifies the selected vendor by the use of an electronic means via the server 230 , such as an HTML form, a chat window, e-mail, etc. For example, the quote Web page depicted in FIG. 8B shows two different quotes with two different tallies, the first quote price 813 of $360, and the second quote price 813 A of $320. If the buyer determines that they prefer to purchase the materials listed in the first quote, the buyer selects the “Buy!” hyperlink 820 or 820 A associated with the desired tally. [0058] If the buyer is not satisfied with any of the listed vendor quotes, the server 230 allows the buyer to further negotiate with one or more of the vendors to obtain a new quote. This step is shown in decision block 611 , where the buyer makes the determination to either accept a quoted price or proceed to step 613 where they negotiate with the vendor to obtain another quote or present a counter-offer. Here, the server 230 provides a graphical user interface configured to allow the buyer and one vendor to electronically communicate, using, e.g., a chat window, streaming voice communications, or other standard methods of communication. There are many forms of electronic communications known in the art that can be used to allow the buyer and vendors to communicate. [0059] The buyer and seller negotiate various quotes and iterate through several steps 603 - 613 directed by the server 230 , where each quote is normalized, compared, and further negotiated until a quote is accepted by the buyer or negotiations cease. While the buyer and seller negotiate the various quotes, the server 230 stores each quote until the two parties agree on a price. At any step during the negotiation process, the system always presents the buyer with an option to terminate the negotiation if dissatisfied with the quote(s). [0060] At decision block 611 , when a buyer agrees on a quoted price, the process then continues to step 615 where the buyer sends a notification message to the vendor indicating they have accepted a quote. As described above with reference to steps 603 - 613 , the buyer notification message of step 615 may be in the form of a message on a chat window, e-mail, by an HTML form, or the like. However, the buyer notification must be transmitted in a format that allows the system to record the transaction. The buyer notification may include all of the information regarding the specifications by RFQ Line Item, such as, but not limited to, the buy price, date, and method of shipment, and payment terms. [0061] The purchase-negotiation process 600 is then finalized when the system, as shown in step 617 , sends a confirmation message to a tracking system. The confirmation message includes all of the information related to the agreed sales transaction. [0062] Optionally, the process includes step 619 , where the server 230 stores all of the information related to RFQ, offers, and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining a lower market price in future transactions and in identifying optimum purchasing strategy. The analysis process is described in further detail below. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0063] Referring now to FIG. 6B , an embodiment of the unsolicited offer process 650 is disclosed. In summary, the unsolicited offer process 650 , also referred to as the unsolicited market purchase process, allows at least one buyer to view unsolicited offers from a plurality of vendors and purchase items from a plurality of vendors from the offers. The logic of FIG. 6B provides buyers with a forum that automatically manages, collects, and normalizes price quotes based on metric data. By the price normalization method of FIG. 6B , the server 230 creates an integrated forum where offers from a plurality of inherently dissimilar products can be obtained and normalized for determination of purchase. [0064] The unsolicited offer process 650 begins at step 651 where the plurality of vendors is able to submit offers to the server 230 . This part of the process is executed in a manner similar to step 603 of FIG. 6A , where the vendor submits a quote to the server 230 . However, in the Web page of step 651 , the server 230 generates a Web page containing several tallies from many different vendors. In addition, at step 651 , the server 230 stores all of the unsolicited offer data provided by the vendors. [0065] Next, at step 653 , a buyer views the offers stored on the server 230 . This part of the process is carried out in a manner similar to the process of step 603 or 607 where the server 230 displays a plurality of offers similar to the tallies depicted in FIG. 8A . [0066] Next, at step 655 , the buyer selects a metric for the calculation of the normalized price associated with the selected offer. As described in more detail below, metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription services such as Crowes™ or Random Lengths™ accessed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the data stored in the server 230 . The normalization calculation, otherwise referred to as the normalization process, occurs each time the buyer views a different offer, and the normalization calculation uses the most current metric data for each calculation. The normalization process is carried out because each vendor will most likely offer products that may vary from products of other vendors and have a different tally configuration from those supplied by other vendors. The normalization of the pricing allows the buyers to compare the relative value of the different products offered by the number of vendors. The metric price for each selected offer is displayed in a similar manner as the metric price 815 and 816 shown in the Web page of FIG. 8B . [0067] Next, at decision block 657 , the buyer selects at least one offer for purchase. This is similar to the process of FIG. 6A in that the buyer selects the “Buy!” hyperlink 820 associated with the desired tally to purchase an order. The process then continues to steps 659 - 663 , where, at step 659 , the process transmits a buy notice to the vendor, then, at step 661 , sends a purchase confirmation to the tracking system, and then, at step 663 , saves the transaction data in the server database. The steps 659 - 663 are carried out in the same manner as the steps 615 - 619 of FIG. 6A . In the above-described process, the buyer notification may include all of the information regarding the specifications by RFQ Line Item, and data such as, but not limited to, the buy price, date, and method of shipment, and the payment terms. [0068] Referring now to FIG. 7 , a flow diagram illustrating yet another embodiment of the present disclosure is shown. FIG. 7 illustrates the catalog purchase process 700 . This embodiment allows buyers to search for a catalog price of desired commerce items, enter their purchase data based on the pre-negotiated catalog prices, and to compare those catalog prices with a selected metric price and the current market price, wherein the current market price is determined by the purchase-negotiation process 600 . [0069] The process starts at step 701 where the buyer selects a program buy catalog 443 . The program buy catalog 443 provides buyers with the published or pre-negotiated price of the desired products. Next, at step 703 , based on the catalog information, the buyer then enters their purchase data. Similar to step 501 of FIG. 5 and the tally shown in FIG. 8A , the buyer sends purchase data to the server 230 , such as the desired quantity of each item and the lumber species, grade, etc. [0070] The process then proceeds to decision block 707 where the buyer makes a determination of whether to purchase the items using the catalog price or purchase the desired product in the open market. Here, the server 230 allows the user to make this determination by displaying the metric price of each catalog price. This format is similar to the metric price 815 and 816 displayed in FIG. 8B . [0071] At decision block 707 , if the buyer determines that the catalog price is better than a selected metric price, the process then proceeds to steps 709 , 711 , and 713 , where a program buy from the catalog is executed, and the buyer's purchase information is stored on the server 230 and sent to the vendor's system to confirm the sale. These steps 711 - 713 are carried out in the same manner as the confirmation and save steps 617 and 619 as shown in FIG. 6A . [0072] At decision block 707 , if the buyer determines that the metric price is better than the catalog price, the process continues to step 717 where the buyer's purchase data is entered into an RFQ. At this step, the process carries out the first five steps 601 - 609 of the method of FIG. 6A to provide buyers with the price data from the open market, as well as provide the normalized prices for each open market quote. At step 719 , the server 230 then displays a Web page that allows the user to select from a purchase option of a catalog or spot (market) purchase. At decision block 721 , based on the displayed information, the buyer will then have an opportunity to make a determination of whether they will proceed with a catalog purchase or an open market purchase. [0073] At decision block 721 , if the buyer proceeds with the catalog purchase, the process continues to step 709 where the catalog purchase is executed. Steps 709 - 713 used to carry out the catalog purchase are the same as if the buyer had selected the catalog purchase in step 707 . However, if at decision block 721 the buyer selects the option to proceed with the market purchase, the process continues to step 723 where the RFQ generated in step 717 is sent to the vendor. Here, the process carries out the steps of FIG. 6 to complete the open market purchase. More specifically, the process continues to step 609 where the buyer compares the normalized prices from each vendor. Once a vendor is selected, the negotiation process of steps 603 - 613 is carried out until the buyer decides to execute the purchase. Next, the transaction steps 615 - 619 are carried out to confirm the purchase, notify the tracking system, and save the transactional data on the historical database. [0074] Optionally, the process can include a step where the server 230 stores all of the information related to program buy and metric comparisons and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining the value of the program. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0075] The analysis process allows the server 230 to utilize the sales history records stored in steps 619 and 711 to generate price reports for communication to various third parties as well as provide a means of calculating current market prices for products sold in the above-described methods. The sales history records are also used as the source for a metric, such as those used in the process of FIGS. 6A, 6B, and 7 . As shown in steps 619 , 663 , and 711 , the server 230 continually updates the historical database for each sales transaction. The analysis reporting process allows a buyer or manager of buyers to conduct analysis on the historical information. This analysis would include multi-value cross compilation for purposes of determining purchasing strategies, buyer effectiveness, program performance, vendor performance, and measuring effectiveness of forward pricing as a risk management strategy. [0076] Referring now to FIG. 9 , a flow diagram illustrating the logic of the normalization process 900 is shown. The logic of the normalization process 900 resides on the server 230 and processes the quotes received from commodity sellers. The logic begins at step 905 where quote data is obtained from the seller in response to the buyer's RFQ as described above. [0077] Next, at step 910 , routine 900 iteratively calculates the board footage (BF) of each type of lumber. Once all the totals are calculated for each type, routine 900 continues to step 915 where the server 230 calculates the total type price. [0078] At step 915 , routine 900 iteratively calculates the total type price for the amount of each type of lumber specified in the quote. This is accomplished by taking the total board footage (BF) calculated in block 910 and multiplying the total BF by the price per MBF specified in the quote. Once all the prices are calculated for each type, routine 900 continues to step 920 where the server 230 calculates the total quoted price. At step 920 , the routine 900 calculates the total price for the quote by summing all of the total type prices calculated at step 915 . [0079] At step 925 , routine 900 iteratively retrieves the most current price for each type of lumber specified in the quote from a predefined metric source(s). Metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription service publications such as Crowes™ or Random Lengths™ accessed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the server database. Once all the prices are retrieved for each type, at step 930 , the routine 900 then iteratively calculates the market price for the quantity of each type of lumber in the quote. Once the totals for all types are calculated, routine 900 continues to step 935 where the routine 900 calculates the total market price for the quote by summing all the most current prices calculated in step 930 . Although this example illustrates that steps 910 - 920 are executed before steps 925 - 935 , these two groups of steps can be executed in any order, or in parallel, so long as they are both executed before a comparison step 940 . [0080] At step 940 , routine 900 compares the total quoted to the metric price to arrive at a comparative value. In one exemplary embodiment of the current invention, the comparative value is a “percent of metric” value. A value higher than one hundred (100) percent indicates a price that is above the metric rate, and a lower percent indicates a price that is below the metric rate. [0081] The operation of routine 900 can be further illustrated through an example utilizing specific exemplary data. In the example, a buyer sends out a request for a quote (RFQ) requesting a lot of 2×4 S&B lumber consisting of five units of 2″×4″×8′, two units of 2″×4″×14′, and five units of 2″×4″×16′. The buyer then receives quotes from three sellers. Seller A responds with a tally of six units of 2″×4″×8′, four units of 2″×4″×14′, and three units of 2″×4″×16′ for $287 per thousand board feet. Seller B responds with a lot of five units of 2″×4″×8′, one unit of 2″×4″×14′, and six units of 2″×4″×16′ for $283 per thousand board feet. Seller C responds with a lot of one unit of 2″×4″×8′, five units of 2″×4″×14′, and five units of 2″×4″×16′ for $282 per thousand board feet. Suppose also that the typical unit size is 294 pieces/unit, and the metric or reported market price for 2″×4″×8's is $287.50, for 2″×4″×14's is $278.50, and for 2″×4″×16′ is $288. [0082] Viewing the MBF prices for the respective quotes is not particularly informative, given that certain lengths of lumber are more desirable and priced accordingly in the marketplace. By processing the quote from Seller A using routine 900 , we arrive at a total MBF of 29.792, giving a total quoted price of $8,550.30. The selected metric price for the same types and quantities of lumber would be $8,471.12; therefore, the quoted price would have a percent of market value of 100.93%. Processing the quote from Seller B using routine 900 , we arrive at a total MBF of 29.400, giving a total quoted price of $8,320.20. The selected metric price for the same types and quantities of lumber, however, would be $8,437.21; therefore, the quoted price would have a percent of market value of 98.61%. Finally, processing the quote from Seller C using routine 900 , we arrive at a total MBF of 30.968, giving a total quoted price of $8,732.98. The selected metric price for the same types and quantities of lumber, however, would be $8,767.66; therefore, the quoted price would have a percent of market value of 99.38%. By looking at the percent of selected metric value, it is apparent that the price from Seller B is a better value. As shown in the methods of FIGS. 5-7 , this price normalization process allows users to compare inherently different offers having different quality and quantity values. [0083] In yet another example of an application of the normalization process, additional exemplary data is used to demonstrate the analysis of a transaction having one RFQ from a buyer and two different quotes from a seller, normalized to comparable product of another species. In this example, the buyer produces an RFQ listing the following items: one carload of Eastern SPF (ESPF) lumber having four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, two units of 2″×4″×14′, and six units of 2″×4″×16′. The vendor then responds with two different quotes with two different unit tallies and two different prices. The first response lists a quote price of $320 per thousand board feet, and a slight modification of the tally provides four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, three units of 2″×4″×14′, and five units of 2″×4″×16′. The second response quotes per the requested tally at a price of $322 per thousand board feet. Both quotes list the delivery location as “Chicago.” [0084] To display the quotes, the server 230 produces a Web page similar to that displayed in FIG. 8C , where the vendor's modified tally is displayed in highlighted text. The buyer can then view summary metric comparison or select the hypertext link “View Calculation Detail,” which then invokes the server 230 to produce a Web page as shown in FIG. 8D . Referring now to the Web page illustrated in FIG. 8D , the data produced by server 230 compares the response to a selected metric of a different species, Western SPF (WSPF), for items of the same size, grade, and tally. The market price for the same 2×4 tally of ESPF and WSPF are thus simultaneously compared. In an example, Eastern quoted at $322 per thousand board feet, Western metric (Random Lengths™ 6/26/2000 print price plus freight of $80 as defined in Metric Manager) for the same tally being $331.791. This metric comparison is also represented as Quote/Metric Value or Eastern price representing 0.970490, or 97% of comparable Western product. [0085] In review of the normalization process, the buyer must select a metric source for price information for a defined item given a set of attributes, i.e., grade, species, and size. The metric may then be mapped to the RFQ item for comparison and does not have to be the equivalent of the item. For instance, as explained in the above-described example, it may be desirable to map the market relationship of one commodity item to another. The most current pricing data for the metric is electronically moved from the selected source to the server 230 . As mentioned above, metric data may come from publicly available information, (i.e., price of futures contracts traded on the Chicago Mercantile Exchange), or subscription services, (i.e., Crowes™ or Random Lengths™ publications), or be an internal metric generated by the server 230 . This metric data is used in the normalization process for all calculations, as described with reference to the above-described methods. [0086] While various embodiments of the invention have been illustrated and described, it will be appreciated that within the scope of the appended claims, various changes can be made therein without departing from the spirit of the invention. For example, in an agricultural commodity, an order for Wheat U.S. #2 HRW could be compared to a selected metric of Wheat U.S. #2 Soft White, similar to how different species are analyzed in the above-described example. [0087] The above system and method can be used to purchase other commodity items, such as in the trade of livestock. In such a variation, order information such as a lumber tally would be substituted for a meat type, grade, and cut. Other examples of commodity items include agricultural products, metals, or any other items of commerce having several order parameters.

A system includes at least one server that implements a metric server adapter and a metrics application. The metric server adapter includes governing logic that manages an evaluation service and predefined instructions and/or data used to provide the evaluation service. The metrics application executes the evaluation service in coordination with the metric server adapter. The server receives or retrieves price data sets, at least one of which represents an unequal offer. The metrics application obtains time-dependent metric data including market reference price data for one or more responsive items, dynamically discovers a difference in the attribute data, and defines offer-specific instructions for adapting the metric data. One or more adjustment values applied to the market reference price data transforms the market reference price data. A comparative metric comprising a differential ratio or index value compares the price data in the offer with the offer-specific market reference price data values.

Related Applications The present invention is particularly directed to use in an adaptive inference testing system which will employ varying features and functions, described in differing aspects in any one or more of the following copending patent applications, including this one, all filed concurrently and assigned to the present assignee: Ser. No. 07/433,612 for "INTERACTIVE ADAPTIVE INFERENCE SYSTEM"; Ser. No. 07/433,591 for "SYSTEM FOR DISPLAYING ADAPTIVE INFERENCE TESTING DEVICE INFORMATION"; Ser. No. 07/433,335 for "METHOD FOR CALCULATING ADAPTIVE INFERENCE TEST FIGURE OF MERIT"; Ser. No. 07/433,594 for "UNPREDICTABLE FAULT DETECTION USING ADAPTIVE INFERENCE TESTING TECHNIQUES". BACKGROUND OF THE INVENTION The present invention relates to an adaptive inference testing device and, more particularly to an array structure for use therein. In the field of electronics in general and in printed circuit board assembly in particular, electronic components are generally mounted, affixed, plugged into or otherwise associated with printed circuit boards. Such electronic components may be analog devices, digital devices, integrated circuits and the like. The boards, in turn, usually have electrical contacts along one or more sides thereof for plugging into connectors. On a typical personal computer, for example, some five to ten boards are provided and are associated, by means of connectors, with a so-called mother board. Of course, more sophisticated machines would tend to have a greater number of boards and less sophisticated instruments would have tend to have fewer boards. As the technology of electronic devices advances and as the consumer market for advanced products matures, not only does the functional complexity and the number of manufactured machines increase, but so too may the number of components per board increase. This makes it difficult to directly access all of the test points required to test a loaded board completely. Finally, components mounted on the boards become ever more powerful and more difficult to test as new functions are required. It therefore has become increasingly important to enhance procedures for testing proper operation of components, boards and machines. To the extent that such testing procedures can be improved, more efficient methods and more accurate methods are ensured. For purposes of this description, the term "adaptive inference" means the ability to predict the cause of a previously unobserved fault from the relationships with other known fault information. Also for purposes of this description, the term "unit under test (UUT)" is used to identify any component or assembly to be tested. Heretofore, UUTs were tested by technicians with the aid of certain instruments as simple as a voltmeter or as complex as a mainframe computer. Such testing methods were necessarily time consuming and labor intensive. More recently, programmable systems have been used to test specific UUTs. These systems tend to be more efficient than manual methods, by allowing a greater number of UUTs to be tested in a given amount of time. But in order to use these programmable systems to test every possible condition of a component or board, every possible stimulant must be applied to the UUT and every possible response must be analyzed or at least compared with its associated proper reference response. Even on a simple UUT, unanticipated problems can arise in many ways. Previous methods required a test engineer to program each of these possible faults into a machine. This required enormous amounts of programming. Over 25,000 lines of code and six months of effort were not unusual. The present invention eliminates this programming effort for fault isolation by mathematically comparing a new fault to previously stored faults. A figure of merit is derived and displayed to indicate likely causes and closeness to known faults. For instance, a certain circuit node may be shorted to ground and the faults recorded and stored in memory. When the same node is shorted to +5v, the acquired data is not going to be identical, but may be very close. In a traditional programming environment, two separate programs would be needed to cover both those cases. But the present invention indicates a high probability (figure of merit) that the indicated node is the source of the fault. Powerful display tools in accordance with the present invention, such as waveform displays with color highlighting to show discrepancies, aid in localizing the troublesome area. A figure of merit less than 100% for faults never before experienced can signal the operator to investigate. In the above example, when the operator discovers that a node is stuck high (not grounded), with a single keystroke the new fault can be added to memory. If the fault occurs again, the message displayed indicates this new fault with a high figure of merit: that same node is likely to be stuck to +5v. The next time the test is run with the same node stuck high, the system displays the message and indicates the second most likely diagnosis is the same node stuck low with a figure of merit less than 100%. In this way, the system accumulates a representation of knowledge that it has gained in the past. It can infer things it has never seen. It operates similarly to the way that a human operator would debug a circuit. Moreover, the system improves with time and, of course, it never forgets. A particularly vexing problem relates to the fact that testing procedures conventionally are performed in a serial manner. That is, the UUT is tested by applying one stimulus thereto and tracing its effect through the UUT, finally arriving at the overall UUT response, which is checked against a reference response. With sophisticated, complex electronic devices, having a great number of possible and appropriate stimuli, each resulting in a different response, the serial technique of the prior art is woefully inefficient and time consuming. Moreover, if a plurality of responses is acceptable for a given stimulus, prior art testing systems are generally inadequate to detect proper operation within a range of values. Baker et al. U.S. Pat. No. 4,847,795 discloses a system for diagnosing electronic assembly defects. The system has a knowledge base for storing information on UUT and receiving current test failure. The system has a pattern search which compares current test data to stored information. A voting section recommends a repair process. The knowledge base is updated with information as to whether or not the repair eliminated the defect. Hogan Jr., et al. U.S. Pat. No. 4,841,456 discloses a system in which an artificial intelligence system is interfaced with an automatic test system such that the actions of the AI are indistinguishable from those of a human operator. The automatic testing system includes an automatic test equipment controller, at least one test instrument and a UUT. There is a storage means for storing a functional test procedure (FTP) for the UUT. The FTP data set contains the results obtained by executing the FTP. An expert system means processes the FTP data and indicates when a failure has occurred and, if possible, the defective UUT portion that may have caused the failure. The expert system means produces output data identifying the defective UUT portion. The automatic test system may also comprise a diagnostic test procedure for the UUT should the expert system determine that further testing is required. It would be advantageous to provide an adaptive inference testing system capable of massively parallel operations. It would also be advantageous to provide an adaptive inference testing system with an array structure. It would also be advantageous to provide such a testing system with a method for comparing test response data with reference response data. It would also be advantageous to provide such an adaptive inference testing system with means for comparing actual test data with a range of proper responses. It would also be advantageous to provide an adaptive inference testing system with a library of errors, which can be updated by an operator. SUMMARY OF THE INVENTION In accordance with the present invention there is provided an adaptive inference system for testing electrical or electronic devices or assemblies. A mechanism is provided for performing position-dependent, time-ordered tests upon electrical or electronic devices in order to obtain a test data array. A mechanism is also provided to define a reference array containing acceptable data for comparison with test data. A comparator is connected to the test data array and to the reference array for providing an error array. An error array library is also provided, which contains accumulated error data. Finally, an error array comparator is connected between the error array library and the error array providing a diagnostic analysis of the electrical or electronic devices or assemblies. BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when taken in conjunction with the detailed description thereof and in which: FIG. 1 is a perspective view of the MFI and MCP of the present invention; FIG. 2 is a perspective view of the probe assembly; FIG. 3 is a block diagram of the MFI and MCP of the present invention; FIG. 4 is a schematic representation of a display on a video monitor; FIG. 5 is a schematic representation of data arrays used in accordance with the present invention; FIG. 6 is a flow chart of the testing process in accordance with the present invention; and FIG. 7 is a schematic representation of the testing process in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is illustrated the preferred physical embodiment of the present invention. The invention includes a microprocessor-based Multifunction Instrument (MFI) 10. The MFI 10 supplies system control and power and can perform complex tasks without requiring a host PC 12, such as is manufactured by IBM CORP. However, when the MFI 10 is connected to inferential software, described hereinbelow, which is hosted on the PC 12, other testing functions can be performed, as described herein. The MFI chassis provides an optional printer connector, not shown, communications connector 14, and a GPIB connector, not shown. A keypad 16 is built into the MFI chassis providing an input interface for stand alone operation. The keypad 16 contains function keys 18 used to respond to MFI menus and data displays, described later herein. A video monitor 18 is connected to the MFI 10 via a monitor cable 20. The video monitor 18 is used during stand alone operation to view data displays and menus, described later herein. The MFI chassis has two hardware modules called plugins 22 and 24 that configure the MFI 10. There are plug-ins 22 and 24 for data acquisition, pattern generation, EPROM programming, EPROM emulation and other functions. The MFI 10 must have at least one plug-in (two plug-ins are shown in the FIGURE) 22 and 24 installed in order to operate as a testing tool. Connected to the plug-ins 22 and 24, in turn, are probes 26, at least one or two for each plug-in 22 and 24, only one of which is shown in FIG. 1. Different types of probes 26 can be used with a particular type of plug-in 22 and 24 to achieve different functions. Referring now also to FIG. 2, there is shown a perspective view of the probe assembly. Probes 26 extend from the plug-ins 22 and 24 (FIG. 1) to test leads 28 attachable to a unit under test (UUT), not shown. In this way, probes are the conduit between the UUT and the MFI 10. Probes 26 contain a set of ground pins 30 and signal pins 32 that are connected by means of test clips 34 to the UUT. Each plug-in 22 and 24 and probe 26 must be correctly matched to perform desired functions (e.g., data acquisition, pattern generation, and continuity testing). A label 36 identifies the function of the probe 26. Referring now to FIG. 3, there is shown a block diagram of the preferred embodiment of the present invention. The inventive circuit testing tool has the microprocessor-based Multifunction Instrument (MFI) 10 connected to an MFI Control Program (MCP) 11 by means of a GPIB interface (shown by arrow), which MCP 11 is hosted on the personal computer 12 (FIG. 1). A printout of the MCP program listing is printed as Appendix A, filed with the aforementioned patent application No. 07/433,612 titled "Interactive Adaptive Inference System", and is herein, incorporated by reference (A copy may also be found in the patented file of this application). Connected to MFI 10 is a unit under test (UUT) 38. UUT 38 may be a large, complex printed circuit board, not shown, or a smaller component that may be disposed on or near such a board. It should also be understood that such a component can be displaced from a larger assembly or disconnected entirely therefrom. Any electrical or electronic device or assembly can be used with the system. The MFI 10 contains a high speed random access memory 42, an address counter 44, a data clock control 46, a state machine 48 and buffer memory 50. State machine 48 is connected to data clock control 46 by means of lines 48a. Data clock control 46 is connected to address counter 44 by means of lines 46a. State machine 48 is connected to plugins 22 and 24 by means of lines 48b. Address counter 44 is connected to RAM 42 by means of lines 44a. RAM 42 is connected to memory 50 by means of line 42a. Connected to plug-ins 22 and 24 are probes 26 and Analog/Digital/Drive/Sensor (ADDS) boards 40. The MFI 10 operates as a logic analyzer, digital pattern generator, continuity tester, signature analyzer, microprocessor, disassembler, digital storage oscilloscope, analog waveform generator, EPROM programmer or EPROM emulator. These functions can be controlled by the MFI 10 in the stand alone mode or by the MCP 11 in the coupled mode. When the MFI 10 is coupled with the MCP 11, the combination of devices can run automatic tests and can learn from the results of completed tests. MFI 10 runs an internal firmware program generating menus and data displays; responding to keypad inputs (stand alone mode); controlling the operation of the address counter 44, data clock 46, ADDS boards 40, and trigger control 48; and responding to the control status and data communication from the host PC 12 running MCP software. A plurality of MFI's may be stacked. When in this mode, one MFI 10 acts as the master processor controlling interfaces, not shown, between the other processors. The multiple MFI's can simultaneously acquire (read) and generate (write) digital and analog data, not shown. Data is acquired or sent via the ADDS boards 40. The MFI 10 typically contains several digital and analog ADDS boards 40. The functionality of ADDS boards 40 (analog/digital, drive/sense) is controlled via MFI menus, described in greater detail hereinbelow. Attached to the ADDS boards 40 are the plug-ins 22 and 24, used to configure the MFI 10 for the data acquisition or pattern generation. Data output to or input from the UUT 38 via the ADD boards 40, plug-in 22 and 24, and probes 26 is resident in the RAM 42. The RAM 42 is structured into 96 channels with each channel being 2K samples deep. All data is stored in the RAM 42. Such data is stored in the RAM 42 as digital data, but represents the analog form. That is, analog data input is converted to digital form prior to storage in RAM 42 and converted from digital to analog form when output from RAM 42. RAM control is performed by the address counter 44, data clock control 46 and trigger control 48. The MFI 10 operates in three states: a) an IDLE state where the data clock 46 is OFF, the address counter 44 is OFF, and no data is being written to or read from the RAM 42; b) an ARMED state where the data clock 46 is ON or halted, the address counter 44 is ON and data is being written to or read from the RAM 42; and c) a TRIGGERED state where the data clock 46 is Stopped, the address counter 44 is stopped, and the contents of the RAM 42 are Frozen. When the MFI 10 is ARMED, it is active either generating data for or acquiring data from the UUT 38. The trigger control 48 determines the length of time the data clock 46 will be operable (i.e., how long the MFI 10 will be ARMED). Trigger control 48 monitors the acquired data searching for sequences of trigger patterns. A trigger pattern is a combinational state of the acquisition channels of the MFI 10. States can be high, low or "don't care". Several trigger patterns can be used simultaneously. Once the specified sequence of trigger patterns has been recognized, the MFI 10 enters a TRIGGERED state. The state machine 48 counts the number of samples past the trigger event. Several triggers can be used to start and stop data collection. Once the RAM 42 is full or the last trigger is reached, the data clock 46 and address counter 44 are stopped and the RAM 42 frozen. The MFI 10 reads the contents of the RAM 42 into local memory 50. Once data is in local memory 50, the MFI 10 can create a data display that is output to the video monitor 18 or transferred to the PC 12 for analysis. The address counter 44 points to a sample address in the RAM 42 where data is either written into or read out of the ADDS boards 40. The data clock 46, which may be sourced externally, determines the speed that the address counter 44 counts through the RAM channels and determines the time between samples. Data clock 46 can be made to operate at a speed greater than the speed at which the UUT 38 would normally operate. In the stand alone mode, the MFI 10 operation described above is controlled by menus 49 accessed via the keypad 16 and viewed on the video monitor 18. Each menu 49a-49k has a series of questions that, when answered, provides the capability to modify or adjust MFI operation. The MFI 10 reconfigures these menus 49 to show only those questions and answers that relate to the types of plug-ins 22 and 24 and probes 26 that have been installed. The first menu that appears when the MFI 10 is activated is the configuration menu 49a. This menu 49a provides information about the present configuration of the MFI 10, such as what plug-ins 22 and 24 are attached, whether the MFI 10 is stacked or uncoupled, which machine or operating state the MFI 10 is in, and what SETUP mode is selected. A SETUP mode is the set of all MFI 10 operating parameters a user can modify on all the menus plus one display parameter. There are two complete setups allowing a user to change setups without having to remodify all the menus. In addition to status information, this configuration menu 49a provides the capability to change configurations. A communication menu 49b sets up the printer ports and the communication ports on the MFI 10. This menu can be accessed only from the configuration menu 49a. The data parameter menu 49c provides the capability to select the display mode, trigger delay, probe and channel options, and auto arm. The trigger delay provides the capability to adjust the number of samples to be acquired after the sequence has been satisfied. The clock menu 49d provides the capability to determine what points in time are to be sample points. Sample points are those points at which acquisition channels sample data and when generation channels output data. The trigger pattern definition menu 49e provides the capability to set up to 14 trigger patterns. The trigger pattern is a set of logic levels, one logic level defining each acquisition channel. Logic levels can be defined as HI, LO, and DON'T CARE for each acquisition channel. When these logic levels simultaneously occur on all the acquisition channels, the trigger pattern has occurred. The trigger sequence menu 49f provides the capability to instruct the MFI 10 to perform different actions as different trigger patterns occur. The pattern generation menu 49g provides the capability to control the pattern generation plug-ins 22 and 24 and probes 26. There are two sources of patterns: algorithmic pattern, useful for generating analog signals; and "from the screen" pattern source which uses data records in the MFI buffer memory 50 as pattern sources. The continuity test menu 49h controls the continuity tester plug-in 22 and 24 and probe 26. The analog menu 49i provides the capability to specify that the data records of selected probes 26 be displayed on the timing display shown on either video monitor 18 or PC 12 (FIG. 1) as analog waveforms. The signature analysis menu 49j provides control over the signature plug-in 22 and 24. The EPROM programming menu 49k provides the capability to control the EPROM plug-in 22 and 24 and probe 26. Data displays that appear on video monitor 18 or PC 12 provide the capability to observe and modify data acquired or generated by the MFI 10. There are four data displays provided with the MFI 10: a) timing display, not shown, displaying waveform data. The timing display acts as an adjustable window on the data record, not shown. The data record is larger than the window, but the window may be moved back and forth or up and down to show the whole data record. The data may also be magnified under the window for more precise observations. b) binary/hex display. These standard displays, well known in the art and not shown in detail herein, provide the capability to examine the data records sample by sample and channel by channel; c) octal display. This standard display, well known in the art and not shown in detail, displays the data record as a sequence of octal data; and d) processor disassembly displays, providing the capability to observe the processor code execution in the assembly language of the UUT processor. Referring now also to FIG. 4, there is shown a typical timing diagram displayed on video monitor 18 or the PC 12 (FIG. 1). The timing diagram display illustrates some of the key concepts described above. This example shows twelve digital channels and one analog channel. In the simplified example observe the following items: DATA CLOCK 72 The user selected sampling rate for the data shown in this display is 20 ns per sample. The dotted horizontal line 73 in the middle of the display shows the actual positions of the sample clock. TRIGGER POSITION 74 The trigger event 75 is indicated by the vertical dashed line. At this point in time, the states of the acquisition channels matched the user described trigger pattern. "Trig=00303" indicates the position of the trigger event as sample number 303 in the record. SCREEN POSITION 76-78 "S=0248" indicates that the left edge of the screen 76 is displaying the 248th sample of the record. At the top right corner 78 "0359" indicates that the right edge of the screen is displaying the 359th sample of the record. Typically, the earliest sample in the record is sample 0 and the last is sample 1023. The last sample number is a function of record size. CHANNELS 80 The indications on the left edge of the display are the channel labels. These labels identify the plug-in probe pin 32 (FIG. 2) that was connected to the point in the user's circuit that generated the waveform 82 to the right of the label. WAVEFORMS 82 The waveforms displayed to the right of each channel label are representations of digital data captured by the MFI. This is the result of ACQUISITION. MFI STATUS 84 This indicates MFI status as either ARMED, TRIGGERED, or as evidenced in this example, IDLE. MAGNIFICATION 86 This indicates the resolution of the display. In this example, MAG=1 shows separate sample points at the highest resolution, 112 samples across the display. TIMING CURSOR INDICATORS 88 These vertical solid lines are used to locate the signal events within the data record or to measure the time period of a signal event. TIMING CURSOR 1 POSITION 90 AND TIMING CURSOR 2 POSITION 92 Indicate the sample number positions of the timing cursors. DIFFERENCE BETWEEN TIMING CURSORS 94 Indicate the number of samples or time units between the timing cursors 90-92. VOLTAGE CURSOR INDICATORS 96 Measure the amplitude of the analog waveforms. DIFFERENCE BETWEEN VOLTAGE CURSORS 98 Indicates the number of vertical divisions between the voltage cursors 96. ANALOG VOLTS PER DIVISION 100 This indicates the vertical scale of the analog channel. Divisions are actually the pixel size on the display. When this example has completed its activities, the MFI 10 has obtained a set of data and stored it in the RAM 42. MFI stand alone operation (FIG. 3) is summarized in the following example of the MFI 10 functioning as logic analyzer. The following example is prescribed for explanatory purposes only and is not intended to limit the scope of the invention as defined by the appended claims. The MFI 10 is configured for this example as follows: capacity of 32 channels of timing data represented by two DDA50 plug-ins 22 and 24 (each with 16 channels digital) and each plug-in 22 and 24 with two P8v probes 26 (each probe with 8 channels available). The probes 26 are attached to a set of circuit boards 38. Each acquisition channel 32 (FIG. 2) on the probes 26 is assigned to a point in the unit under test 38 (FIG. 3). Each channel acquires logic level samples (1's and 0's) from the point in the UUT 38. Sampling occurs at points in time (sample points) determined by the operator's selected data clock 46. An analog channel uses eight digital channels in the preferred embodiment to represent the analog wave form. Sampling begins when the MFI 10 is ARMED. The MFI 10 is ARMED when one of the following occurs: The Arm Key Trig Key on the keypad 16, or the MFI 10 receives an Arm Key or Trig Key command over the communications port 14 from the MCP software 11, while the MFI 10 is IDLE (not ARMED). The MFI 10 is triggered while in AUTO-ARM mode. Sampling stops when one of the following occurs: The MFI 10 is disarmed by pressing the Arm Key on the keypad 16 or sending the Arm Key command to the communications port 14 to the MCP software 11, while the MFI 10 is ARMED. The MFI 10 is triggered. The MFI 10 is triggered by one of the following: The occurrence of a specified sequence of trigger patterns followed by a trigger delay number of data clocks 46. The Trig Key on the keypad 16 is pressed or the Trig Key command is sent to the communications port 14 to the MCP software 11. When the MFI 10 is triggered it will display the acquired data on the video monitor 18 or on the PC 12. Each channel maintains a data record of the most recent samples. The number of samples in a channel's record is determined by the plug-in 22 and 24 type and data clock 46 for that channel. The record size can also be affected by concurrent pattern generation within the MFI. Generally, the record size is from 512 to 8192 samples. A trigger pattern is an operator defined combinational state of input channels. For a particular trigger pattern, the user can assign a state for each acquisition channel, a 1 or a 0 or an x (for "DON'T CARE"). When this combination of states occurs simultaneously on the acquisition channels, the defined trigger pattern is said to have occurred. ______________________________________ TRIGGER PATTERN______________________________________PROBE # 22221111111100000000Pin # 32107654321076543210TP01 XXXXXXXXXXXXXXXXXXXX______________________________________ When the MFI 10 is triggered, the channel records are available in their final form to be viewed on the MFI's display screens. These records may be viewed as timing diagrams (FIG. 4) or as one of many data domain displays, including microprocessor disassembly, that the MFI 10 can generate. The above discussion on the invention data acquisitions/sending operations is the same in either the stand alone mode (MFI 10 controls the activity) or the coupled mode (MCP 11 controls the activity). Referring now again to FIG. 3, the MFI control program (MCP) 11 provides the capability to use PC based technology to control and enhance the performance of the MFI 10. The MFI 10 is connected to the MCP 11 by standard interfaces 14 (e.g., RS-232 communications port or GPIB IEEE-488 interface). The MCP 11 operates as a menu driven, interactive program organized into six major functions: control 52, editing 54, filing and transfer 56, viewing 58, testing 60, and other 62. The control menu 52 provides the capability to control the MFI 10 directly, including the MFI menus 49. There are two modes associated with this menu: a) blind control provides keys on the PC keyboard as replacements for the keys on the MFI keypad 16. Control is exercised by using the keyboard keys to interact with the menus and displays produced by the MFI 10; and b) remote control provides the capability to replace both the MFI keypad 16 and monitor 18 with the PC 12. The PC 12 displays the current MFI display on one half of the monitor 18 and displays valid MCP control keys on the other half. Editing menus 54 provide the capability to change or modify data contained in the MCP memory 50. Data can be edited using either the digital/analog waveform display (such as illustrated in FIG. 4) or the hexadecimal character display. Additional functions are provided to edit the waveform display; mark, unmark, copy, fill, and duplicate digital waveform segments; generate digital counting patterns; generate simple analog waveforms; and perform mathematical operations on analog waveforms. Filing and transfer menus 56 provide the capability to control the transfer of information between the MFI 10 and the MCP 11. It allows the MCP 10 and MCP 11 to share setups and data. Setups are the copy of all working menu variables and reflect menu settings (MFI menus 49a-49k and MCP menus 52-62). Filing functions provide disk accessing and storage on the PC disk system. Viewing menus 58 provide the capability to select the data being displayed, to label and arrange the order of the channels in the display, to control the resolution of the display, to display specific portions of the data, and to select between a waveform representation and a hexadecimal character representation. Testing menus 60 provide the capability to test chips, circuits, PC boards, and other electrical or electronic devices or assemblies. The MFI 10 is automatically reconfigured for a specific test through the filing functions. Other menus 62 provide the following miscellaneous functions: setting communications baud rate, copying among buffers, listing files in the working directory, changing directories, outputting a control byte to the parallel port, uploading and downloading EPROM images. In addition to the aforementioned menus 52-62, the MCP 11 provides the capability to record operator commands as they are entered from the PC 12 (FIG. 1) keyboard or keypad 16 and to execute these sequences on command, generating the same activity as when they were first recorded. The macro functions 64 allow the MCP 11 to run tests without operator interaction. Referring now also to FIG. 5, there is shown a schematic representation of data arrays as used in accordance with the present invention. In operation, test vectors 102 are applied to a unit under test (UUT) 38. While UUT 38 is usually a printed circuit board, it may also be a single device. The invention contemplates several ways of creating test vectors 102. If UUT 38 contains a microprocessor or other intelligence, and actually performs a function when the power is turned on, MCP 11 (FIG. 3) can learn the function of UUT 38 by connecting to it and observing the normal response. Alternatively, an operator can visually create test vectors using a highly interactive graphical user interface and editor. Another method to create test vectors is to download simulation data from a computer aided design (CAD) system database, not shown, to PC 12. When a device or a board is designed, a simulation using a CAD system is often created to validate the design. While such a simulation may not be perfect information for the test process, it is usually a good starting point. Test vectors 102 are applied to UUT 38 to acquire data for the board under test 38. An acquired data plane or array 104 is generated as a result of applying test vectors 102 to UUT 38. Circles 104a-104c in FIG. 5 indicate information gathered. The two-dimensional representation of this plane of information 104 illustrates one of the unique features of the invention. Wherever a test point is interrogated, information is gathered continuously in the form of a data array. For purposes of this description, it is useful to know that reference data are the responses and information gathered from a known good board. Data represented by three circles 104a-104c on the acquired data plane 104 are compared to reference data 106a, 106b on reference data plane 106. A single test is sufficient to obtain a reference. A number of good boards 38 can be used to create a tolerance data plane 108. Since a known good board can have variations that are considered normal, the tolerance plane 108 is a representation of the normal variations of a known good board. For example, a pulse might be one millisecond wide on the board that is being measured. But it is quite likely that a range of, say, from 0.9 to 1.1 milliseconds is valid normal acceptable data. One could measure a plurality of good boards (e.g., 50 boards) and vary their power supply and temperature to learn normal variance from the good boards. Alternatively, one can use an interactive graphical user interface, hereinbelow described in greater detail, and "tolerate out" (i.e., specify) that range of values, 0.9-1.1 milliseconds. Thus, test vectors 112 are applied to UUT 38 to acquire data 104. Reference data 106 from one good board is already in memory. A simple logical compare (EXCLUSIVE NOR) is performed on a bit-by-bit basis hundreds of thousands of times between the acquired data 104 and the reference data 106. Any deviations between data in the two planes 104, 106 are then compared to data in the tolerance data plane 108. Here a logical AND operation is used as a mask. Any deviations that have been seen in the first array operations are now compared to this mask 108 again. In this way, massively parallel logical operations occur hundreds of thousands of times. By the time the error plane 110 is reached, all deviations which have been observed or predicted by simulations are identified. The mode of analyzing data is far different than traditional methods. As a result, faults are defined that would simply be missed by other kinds of test systems. To build tolerance, an operator decides that the deviations are acceptable; acquired data 104 is compared to reference data 106 and any variances within the tolerance plane 108 are accepted. Once tolerance has been built up, the system is ready to check for errors. Acquired data 104 not favorably compared to reference data 106 nor within tolerance plane 108 results in errors, stored in an error plane 110. An error is defined as an acquired response that is not tolerated out. A pass/fail, go/no-go test can be performed at this point. If there are no errors, the board under test 38 passes. If, however, errors exist, the system can memorize data patterns of faults as well as data patterns of known good boards. If there is a variance, the system can identify that condition and associate that pattern with an English language message 116 previously provided by an operator. For example, "U2, pin 3 Shorted to Ground" would be the sort of message that an operator might see, which is associated with a purely internal mathematical representation. One advantage of this diagnosis is that the system can provide an associated fault with an English language message, which an unskilled operator can then use to debug a UUT 38. The system can store many of these fault patterns, each under a different message. In the process of learning what a good board is or in the process of creating reference data 106, an operator can train the system with a certain number of known faults. In this case, the operator essentially provides the system with a knowledge of faults. For example, U2, pin 2 can be shorted to U2, pin 3. When the test is run, it will fail and the operator enters the appropriate error message. This fault is added to a directory 116 with that English language message. This process can be repeated for different intentionally provoked faults. Subsequently, a test is performed on another UUT 38, resulting in an error. The board fails and the system checks its memory to see if the fault patterns match any that has been seen before. If such a match occurs, the appropriate English language message is displayed. In such a case, the system indicates close to 100% certainty that an error is caused by a fault previously stored. Referring now also to FIG. 6, there is shown a flow chart of the testing process. Test vectors and test parameters are entered into the MCP 11, step 118. These vectors and parameters are downloaded, step 119, into the inferential software 68 (FIG. 5). As explained above, the system enters an ARMED state, step 121, where data is acquired from the UUT 38 until the Trigger is encountered when data is sent to the MCP 11 via the interface 14. Reference and tolerance data are developed, step 120. Initially, these data are developed by setting the reference data set to test data and setting the tolerance data to zero or by using the waveform editor 54 (FIG. 1). Test data acquired from the UUT 38 is compared to the reference and tolerance data, step 124. Results, step 122, that differ from the reference and tolerance data are entered into the fault database. From known good boards, the tolerance data is increased by the difference, step 120. Failure data is passed to fault image and displayed, step 126. Fault isolation improves with increased fault database size. The operator directs any newly discovered fault to the fault database, step 128. At this point in the process the operator can edit any previous diagnosis. The operator can set the testing options, step 130, and the diagnosis options, step 132. Referring now again to FIG. 5, the inferential software 68 provides the capability to "learn" to recognize fault conditions in analog and/or digital signals. A fault directory is either created by simulating failures or by learning faults as they occur during normal testing. Once fault data is stored in memory, a newly-detected fault can be compared with the stored faults. A relationship between the stored fault data and the detected fault is determined. The system indicates the cause of the detected fault to the operator based on stored fault data that is most probably related to the detected fault. This system analysis and range of potential causes can be evaluated by an operator. Referring now to FIG. 7, there is shown a schematic representation of the inferential software principles behind the testing strategies. These strategies are summarized below: Repeatable Results The principle utilized in testing assumes that the operation of a circuit may be judged by examining its operating signals. The first step in developing any test is to devise test vectors and acquisition points that, when applied to the unit under test 38, will produce the same results repeatedly. A device that is working properly will produce a predictable and identifiable result. It is assumed that any deviation from predicted operation is produced by an error in the UUT 38. That UUT 38 has failed the test. Reference and Tolerance Comparison Even devices which are working properly may show some normal drifting and timing jitter between successive iterations of the same test. The test mechanism was designed to cope with this problem. In order for the MCP 11 to be able to determine when a device passes and when it fails, the software must have a standard to judge the incoming results (the Acquired data 133). This standard is referred to as the reference image 134. In most cases, the reference image 134 is simply a copy of the first set of results returned by a good device. The test is performed again and the new results are compared against the old results and stored in the reference image 134. Any differences that occur between successive tests of the same device are recorded in the tolerance image 136. Once all the deviations of the good device are characterized, the good device will always pass because any deviations from the norm have been recorded in the tolerance image 136 and are ignored. This procedure is then repeated with other known good UUTs 38 until the tolerance image 136 has become broad enough to include all the discrepancies which normally occur among properly working UUTs 38. Error Pattern Processing The inferential software, shown in FIG. 7 with dashed lines and identified by reference numeral 68, assumes that, depending upon the specific test configuration, unique faults in the unit under test 38 will produce unique patterns of discrepancies. One fault, a bad chip for example, might cause massive failures all across four channels; whereas another fault, say one signal stuck low, might cause failures during only part of the test on only one channel. In each case, the position, timing and location of the resulting test deviations show that each fault produces a very different pattern of failures in the test data 144. The function of the inferential software 68 can be expressed as follows: 1) Reduce the actual test failure data to a failure synopsis, or fault pattern, which is saved in a database file assigned automatically on a test by test basis. 2) Associate a specific fault diagnosis or comment with each fault pattern stored in the database 138. 3) Compare the incoming fault pattern with all patterns in the database and display the diagnosis descriptions of patterns that match closely 142. 4) Provide a menu-driven interactive interface for developing, utilizing, and maintaining the fault diagnostic databases. Inferential software 68 keeps a record, or mathematical representation, of the specific error patterns that occur in the process of testing. When a fault pattern is added to the database 138, it is associated with an operator-defined 64-character string referred to as the fault diagnosis 140. Initially, the fault patterns can be associated with a descriptive comment. As the causes for these errors are determined, the initial comment can be replaced with the diagnosis. The next time an error occurs, the inferential software 68 will report any fault patterns in the database 138 that are similar to the new fault pattern. Once an error has been identified by the user, the inferential software 68 will be able to recognize and diagnose that error with a high degree of accuracy because it will recognize that fault's unique pattern. Furthermore, even when processing a pattern for the first time, the inferential software 68 will correlate to the most likely fault already stored and will display at least the best match it can find. The inferential software 68 is an extension of the testing mechanism already inherent in the MCP 11 (FIG. 3), so all user access to the inferential software 68 is achieved through the testing functions menus 60 (FIG. 3) of the MCP 11. The inferential software database 138 is maintained in two files (in addition to those generated by the MCP 11 itself). The names of these fields are derived from the MCP 11 data file name and the currently loaded storage frame number. For example, if the full filename of the data file currently open is "TSTNAME.DAT", the following files would be created during test development and diagnosis: TSTNAME.22 Reference file 106 and tolerance file 108 for frame 22. TSTNAME.F22 Inferential software database 138 file of fault descriptions for frame 22. TSTNAME.X22 Inferential software database 138 file of fault patterns for frame 22. The fault description file 137 name is formed, as shown above, by taking the reference file 106 name and inserting the letter `F` between the period `.` and the frame number. This file consists of linefeed terminated strings, each within a fixed 80-character cell. It is possible to use the DOS "TYPE" command or any standard ASCII text editor to display this file. The index number refers to the fault's actual position in the file. The fault pattern file 139 name is formed in the same way as the fault description file 106 except that the letter `X` is inserted instead of the letter `F`. This file consists of fixed size blocks; each block contains one fault pattern. The index number of a fault pattern is identical to the index number of its corresponding position. The fault diagnosis menu 146 is the focal point for all inferential software 68 activity. On entry to this menu 146, the current failures are abstracted from the exception buffer, not shown, and a new fault pattern is formed, which is matched automatically against all patterns in the database 138. Diagnoses are displayed by group according to the percentage of correlation (figure of merit) between the new fault pattern 139 and each fault in the database 138. Each fault description 116 (FIG. 5) is labeled with its unique fault index. A list of fault diagnosis menu functions appears in Table I, below. Table I. FAULT DIAGNOSIS MENU FUNCTIONS Best Conduct the matching process again in order to display the group of faults which match best. Change Select a specific fault by its index and change the fault description or comment. Delete Select a specific fault and delete it from participation in the matching process. Examine Select a fault and examine the associated error pattern synopsis. Find Find all fault descriptions which match the target string entered by the user. Include Include the new fault pattern under an existing description. List Generate the same display as the Examine function, also sending it to the standard print device. New Add the new error pattern to the database with an associated diagnosis or comment. Options Select Fault Diagnosis Options such as fault type and weight. Query Query the database for matches against a specific fault pattern already in the database. Replace Replace the fault pattern for an existing description with the current fault pattern. Show Next Display the next best group of matching diagnoses. Test Return to the Testing Menu (FIG. 3) 60 and execute the Test function. ESC Return to the Testing Menu (FIG. 3) 60. The figure of merit (FOM) is displayed for each group of faults displayed. This value is a percentage from 0 to 100 which indicates how closely the listed fault patterns match the new fault pattern. A figure of merit of 100% indicates that the listed fault pattern matches the new pattern exactly, whereas 0% indicates that the patterns do not match at all. In order to understand how the figure of merit is calculated, it is helpful to imagine an error plane consisting of "channels" on one axis and "time samples" on the other. All entries are normally binary zero. Each time a discrepant value (i.e., an error) is found, a binary one is placed in the array. The number of channels is arbitrarily 96 and the number of time samples is 2K (i.e., 2048). The contents of each channel is a number (e.g., 2K in the preferred embodiment) of binary data samples representing error information from the UUT collected during a test frame. It is desirable to represent the contents of each channel in several forms, each providing a different way of looking at the data. Three ways of describing this information are by means of BIT, GROUP and RANGE. BIT is a binary word representing the number of errors in the 2K record. GROUP is a binary word representing the number of times the error data goes from "no error" to "error". RANGE includes bits that, when set, represent the case when a segment contains an error. The 2K record is divided into sixty four, 32-bit segments. In the following example, data are placed in groups of eight for simplicity of discussion herein. __________________________________________________________________________00111010 11110000 01010100 00000000 Derived No.__________________________________________________________________________BIT 4 + 4 + 3 + 0 = 11GROUP2 + 1 + 3 + 0 = 6RANGE 1 = 1__________________________________________________________________________ Each of the aforementioned three derived numbers is stored on a per channel basis. The FOM calculation uses the three derived numbers as a basis of its calculations. It is desirable to generate a 1 (100%) if all errors match and a 0 (0%) if no match exists. In normal operation, these numbers are stored for each specific error pattern. Each pattern has an English language message associated therewith. The test is run on a new UUT and the three derived parameters are generated. These parameters are compared with stored fault information in the following way, in which the following terms are defined as shown below. Base Bits=No. of error bits in stored error plane. New Bits=No. of error bits in acquired error plane. Match Bits=No. of error bits in common between Base Bits and New Bits. Using the above-mentioned BIT, GROUP and RANGE numbers independently, the following ratios are calculated. ##EQU1## As can be seen by the foregoing equation, the figure of merit as reported on the monitor represents the weighted average of the different methods. Moreover, other sources of information can be used in this manner, without departing from the scope of the present invention, to contribute to the weighted average. In particular, serial bit streams (as in J-Tag and other boundary scan information) complete data without BIT, RANGE or GROUP calculation. Encoding schemes, including transition encoding, to preserve all information in a compressed form are all valid ways to create a FOM using this technique. Many other ways are possible to accent a way that a UUT might fail in practical situations. Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

An adaptive inference system for testing electrical or electronic devices or assemblies. A mechanism is provided for performing position-dependent, time-ordered tests upon electrical or electronic devices in order to obtain a test data array. A mechanism is also provided to define a reference array containing acceptable data for comparison with test data. A comparator is connected to the test data array and to the reference array for providing an error array. An error array library is also provided, which contains accumulated error data. Finally, an error array comparator is connected between the error array library and the error array providing a diagnostic analysis of the electrical or electronic devices or assemblies.

BACKGROUND OF THE INVENTION This invention relates to a printhead and a printing apparatus using the printhead, and more particularly, to a printhead which performs printing in accordance with an ink-jet method and a printing apparatus using the printhead. In ink-jet printing, noise upon printing is very small and negligible, and printing speed is high, further, a print image can be fixed onto a so-called normal paper without special processing. Recently, attention is focused on the ink-jet printing method having these advantages. Among ink-jet printing methods, a printing method disclosed in Japanese Patent Publication Laid-open No. 54-51837 and DOLS No. 2843064, for example, has a feature different from other ink-jet printing methods in that thermal energy is applied to liquid such as ink so as to obtain a driving force for discharging the liquid. That is, according to the above printing method disclosed in these publications, printing is performed by causing a state change with sudden volume increase in the liquid acted upon by the thermal energy, then discharging the liquid from an orifice at the end of a printhead by the action based on the state change, as liquid droplets, and attaching the liquid droplets to a print medium. Especially, according to DOLS No. 2843064, the method is very effectively applied to so-called drop-on-demand printing. Further, the method easily realizes a full-line type printhead having a printing width corresponding to the entire width of a print medium and orifices in a high density. Accordingly, high-resolution and high quality image can be printed at a high speed. The printhead to which the printing method is applied has orifices to discharge liquid, liquid channels, connected to the orifices, each including a heat action portion to supply thermal energy to liquid, and a substrate having electrothermal transducers (heat generators) to generate the thermal energy. Recently, the substrate not only holds the plurality of heat generators but also integrates a plurality of drivers to drive the respective heat generators, a logic circuit including a shift register for temporarily storing image data of number of bits corresponding to the number of heat generators, to transfer the image data serially inputted from a printing apparatus to the respective drivers in parallel, a latch circuit which temporarily latches data outputted from the shift register, and the like. FIG. 16 is a block diagram showing the arrangement of a logic circuit in a conventional printhead having N heat generators (printing elements). In FIG. 16, reference numeral 400 denotes a circuit board; 401 , heat generators; 402 , power transistors; 403 , an N-bit latch circuit; and 404 , an N-bit shift register. Numeral 415 denotes a sensor for monitoring resistance values of the heat generators 401 and the temperature of the circuit board 400 and a heater to maintain the temperature of the circuit board 400 . The sensor may be integrated with the heater, or a plurality of sensors and heaters may be packaged. Numerals 405 to 414 and 416 denote input/output pads. Among these input/output pads, the pad 405 is a clock input pad for inputting a clock (CLK) to operate the shift register 404 ; the pad 406 , an image data input pad for serially inputting image data (DATA); the pad 407 , a latch input pad for inputting a latch clock (LTCLK) to hold image data in the latch circuit 403 ; the pad 408 , a drive signal input pad for inputting a heat pulse (HEAT) to externally control driving period by turning the power transistors 402 ON to energize the heat generators 401 ; the pad 409 , a drive power input pad for inputting a driving power (3-8V; generally 5V) for the logic circuit; the pad 410 , a GND terminal; the pad 411 , a heat generator power input pad for inputting power to drive the heat generators 401 ; the pad 412 , a reset input pad for inputting a reset signal (RST) to initialize the latch circuit 403 and the shift register 404 ; and the pad 413 , an HGND terminal for heat generator drive power source. Further, numerals 414 a and 414 b denote an output pad for outputting a monitor signal and an input pad for inputting control signals for sensor drive and drive of the temperature maintaining heater. Further, numerals 416 -( 1 ) to 416 (n) denote block-selection signal input pads for inputting block selection signals (BLK 1 to BLKn) for block selection in time-division drive. In time-division drive, the N heat generators are divided into n blocks, and driven in block units. Numeral 417 a denotes AND circuits which calculate the logical products of the outputs from the latch circuit 403 and the block selection signals (BLK 1 to BLKn); and 417 b , AND circuits which calculate the logical products of outputs from the AND circuit 417 a and the heat signal (HEAT). Numerals 418 a and 418 b denote parasitic resistances which occur on the wiring used for driving the heat generators 401 . The drive sequence of the printhead having the above construction is as follows. In the following description, image data (DATA) is binary data where 1 bit corresponds to 1 pixel. First, the image data (DATA) is serially outputted from a printing apparatus main body to which the printhead is attached, in synchronization with a clock (CLK), then the data is inputted into the shift register 404 . Next, the image data (DATA) is temporarily stored in the latch circuit 403 , and ON/OFF outputs in correspondence with image data value (“0” or “1”) are made from the latch circuit 403 . In this state, when a heat pulse (HEAT) and a block selection signal are inputted, power transistors supplied with ON outputs from the latch circuit 403 , corresponding to heat generators in a block selected by the block selection signal, are driven for “ON” period of the input heat pulse (HEAT). Then, an electric current flows through the corresponding heat generators. Thus, the print operation is performed. Next, the parasitic resistances 418 a and 418 b will be described. It is preferable that the parasitic resistance does not exist, however, actually it cannot be ignored. The example of FIG. 16 shows the parasitic resistances in the logic circuit of the printhead, however, parasitic resistance also exists on a PCB (printed circuit board) within the printhead or a flexible printer cable (FPC) connecting the printhead and the printing apparatus. In FIG. 16, as the resistances are common to the plurality of heat generators 401 , the ratio between the parasitic resistances and the resistance of all the driven heat generators differs dependent on the number of time-divisionally driven heat generators. As a result, the value of a voltage applied to the heat generators (in other words, the value of voltage drop by the parasitic resistances) changes. Accordingly, the voltage applied to both ends of the heat generators changes due to the duty of a pattern to drive the heat generators, which causes variation in energy to the heat generators. On the other hand, in accordance with the recent tendency of increase in printing speed, a growing number of heat generators are provided in a printhead, and the drive frequency is increasing. In time division drive, the number of simultaneously-driven heat generators is increasing, therefore, the change of voltage drop due to parasitic resistance is not negligible. Conventionally, some methods to prevent voltage drop have been proposed. One of these methods is to feed-back control a heat pulse (HEAT) to drive heat generators, on the printing apparatus side, so as to change the pulse width based on a pattern for driving the heat generators of the printhead. More specifically, as shown in FIG. 17A, on the printing apparatus side, a counter 801 counts the number of simultaneously-driven heat generators based on generated image data, then the counted number is stored into a memory 802 . A drive pulse generator 803 modulates the pulse width based on the number. Otherwise, as shown in FIG. 17B, the counter 801 provided in the printing apparatus counts the number of bits of serially-transferred image data at each time-division drive, and the drive pulse generator 803 controls the pulse width based on the counted number. Further, Japanese Patent Publication Laid-open No. 2-508 discloses a technique to count the number of simultaneously-driven heat generators and to control the pulse width. However, in the conventional art, the shift register and the latch circuit, which have been already provided in the printhead, a circuit to recognize a pattern to drive the heat generators by time-division drive, a counter circuit used for changing the heat pulse width and the like, must be provided on the printing apparatus side. Thus, control on the printing apparatus side is complicated, and the production cost of the apparatus increases. The complexity of control will be described with reference to FIG. 18 . FIG. 18 shows image data of a character “H” represented as a 16×16 matrix with 16 dots in a printhead scanning direction and 16 dots in direction of nozzle array of the printhead. Generally, image data generated in the printing apparatus main body is sequentially transferred in accordance with the order of numbers allotted to the matrix, from “1” to “256”, as shown in FIG. 18 . However, when the above data is transferred to the printhead, the order of data transfer is changed in accordance with the construction of the printhead, and the processed data is transferred. That is, in accordance with the number of nozzles and the printing cycle of the printhead, the order of data transfer is rearranged. As shown in FIG. 18, the transfer order in a case where the number of nozzles of the printhead is “8” is different from that in a case where the number of nozzles is “16”. Further, as described above, the heat generators of the printhead are time-divisionally driven in one printing cycle. Thus, the control is very complicated since factors to be considered include various numbers of nozzles of the printhead, the number of simultaneously-driven blocks, and the number of simultaneously-driven heat generators based on image data, and these factors must be fed back for modulation of the pulse width to drive the printhead. The complicated control will be considered with the examples of FIGS. 17A and 17B. In FIG. 17A, calculation processing is complicated since image data to be subjected to counting dynamically changes in accordance with the construction of the printhead such as the number of nozzles, simultaneously-driven blocks and the like, and the change must be considered in counting processing. On the other hand, in FIG. 17B, as the number of simultaneously-driven heat generators in one printing cycle changes in accordance with the construction of the printhead, the process of transfer image data is complicated. In both cases, the increase in processing load on the printing apparatus main body side cannot be avoided, and in conventional technique nothing could undertake the processing load on the printhead side. Further, although the printhead and the printing apparatus are separable, and they are separately manufactured, further, the printhead is exchangeable, in the controller of the printing apparatus side, not only data interface with respect to the printhead but also the construction of the printhead must be considered. Thus, development and design of printing apparatus have been very troublesome. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a printhead with a comparatively simple construction, which reduces the cost of the entire system and development load, effectively utilizes an essential constituent devices of a logic circuit of a printhead such as a shift register, while omits control on a printing apparatus side, and performs stable print operation by itself, while suppresses variation of energy to heat generators due to voltage drop by parasitic resistance, and a printing apparatus using the printhead. According to one aspect of the present invention, the foregoing object is attained by providing a printhead having plural heat generators, a driver which drives the plural heat generators, and a divider which divides the plural heat generators into plural blocks and time-divisionally drives the plural blocks based on an externally-inputted block selection signal, comprising: a counter which counts the number of simultaneously-driven heat generators based on externally-inputted image data and the block selection signal; and a modulator which modulates a pulse width of a drive signal applied to the simultaneously-driven heat generators based on a value obtained from counting by the counter. Preferably, the modulator has an input pad in which a signal used for modulating the pulse width of the drive signal is inputted. The modulation circuit has various embodiments in accordance with the type of signal inputted into the input pad. That is, in a case where the printhead further comprises a plurality of input pads, and drive signals having different pulse widths are respectively inputted into the plurality of input pads, it is preferable that the modulator includes: (1) a memory for storing a plurality of threshold values; (2) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (3) a selector which selects one of the plurality of drive signals having different pulse widths in accordance with the result of comparison by the comparator. Further, in a case where a clock signal used for inputting the image data is inputted into the input pad, it may be arranged such that the modulator includes: (1) a generator which generates a plurality of drive signals having different pulse widths based on the clock signal; (2) a memory for storing a plurality of threshold values; (3) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (4) a selector which selects one of the plurality of drive signals having different pulse widths generated by the generator, in accordance with the result of comparison by the comparator. Alternatively, the modulator may include: (1) a memory for storing a plurality of threshold values; (2) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (3) a generator which generates a drive signal having an optimum pulse width, based on the clock signal, in accordance with the result of comparison by the comparator. Further, in a case where the printhead further comprises: an N-bit shift register which inputs the image data; an N-bit latch circuit which latches N-bit image data stored in the N-bit shift register; and N AND circuits which obtain logical products of the N-bit image data outputted from the N-bit latch circuit and the block selection signal, the counter counts the number of simultaneously-driven heat generators based on outputs from the N AND circuits. It is preferable that outputs to heat generators which are not simultaneously driven in time-division drive are connected to one of common signal lines, and the common signal lines are connected to the counter. Note that the circuit related to common signal lines has various embodiments. That is, it may be arranged such that (1) the common signal lines are pulled up, and inverters are provided between the common signal lines and the N AND circuits, or (2) the common signal lines are pulled down, and open-drain or open-collector outputs from the N AND circuits are connected to the common signal line, or (3) the common signal lines are pulled down, and amplifiers are provided between the common signal lines and the N AND circuits, further, open-drain or open-collector outputs from the amplifiers are connected to the common signal lines, or (4) the common signal lines are pulled down, and diode switches are provided between the common signal lines and the N AND circuits, further outputs from the diode switches are connected to the common signal lines, or (5) in addition to the construction (4), a bus terminator is connected to an end of each of the common signal lines. Further, the number of common signal lines is equal to or more than a maximum number of heat generators simultaneously-driven in the time-division drive, and less than the number of the heat generators. Further, the counter is preferably an adder, and the adder adds up outputs from the common signal lines. It is preferable that the modulator performs modulation such that when the number of simultaneously-driven heat generators obtained from counting by the counter is larger, the pulse width of the drive signal is wider, while when the number of simultaneously-driven heat generators obtained from counting by the counter is smaller, the pulse width of the drive signal is narrower. Preferably, the printhead is an ink-jet printhead which performs printing by discharging ink. In this case, the printhead has an electrothermal transducer which generates thermal energy to be supplied to the ink, to discharge the ink by utilizing the thermal energy. According to the present invention, the foregoing object is attained by providing a printing apparatus which performs printing by using the printhead having the above construction. In accordance with the printhead of the present invention as described above, the pulse width of a drive signal applied to heat generators is automatically modulated in the printhead in accordance with the number of simultaneously-driven heat generators which always changes based on image data. The invention is particularly advantageous since the variation in energy to the heat generators, due to the number of heat generators driven in the printhead and parasitic resistance of the printhead, can be suppressed, thus stable printing operation can be performed. In this construction, it is not necessary to control the energy to the heat generators so as to reduce the variation in the energy due to parasitic resistance of the printhead on a printing apparatus side, and it is not necessary to provide special circuits on the printing apparatus side. This results in suppressing increase in production cost. Further, as it is not necessary to consider the characteristic of a printhead in development and design of a printing apparatus, the printing apparatus can be developed independently of the printhead. Further, according to the Invention, as the signal used for modulating the pulse width of the drive signal in the modulation circuit is one of drive signals having different pulse widths or a clock signal used for image data input, it is not necessary to generate specific data on the printing apparatus side. Also, it is not necessary to process the specific data on the printhead side. Thus, the pulse width of the drive signal can be modulated with a simple construction. Further, according to the present invention, as signal lines used for counting the number of simultaneously-driven heat generators are commonly used, the area of circuit board can be reduced, thus the printhead can be downsized. Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. FIGS. 1A and 1B are block diagrams showing a portion to count the number of simultaneously-driven heat generators based on image data, and a problem accompanying counting by the part in FIG. 1A; FIGS. 2A and 2B are block diagrams conceptually showing the reduction of the number of count lines; FIG. 3 is a block diagram showing an example of the construction of a circuit which feeds back the number of simultaneously-driven heat generators to heat pulse signal modulation; FIG. 4 is a block diagram showing the relation between a printing apparatus and a printhead according to the present invention; FIG. 5 is a perspective view showing the structure of an ink-jet printer IJRA as a representative embodiment of the present invention; FIG. 6 is a block diagram showing the construction of a controller of the ink-jet printer IJRA; FIG. 7 is a partially-cutaway perspective view showing the internal structure of the printhead mounted on the printer in FIG. 5; FIG. 8 is a block diagram showing the construction of a logic circuit of a printhead IJH; FIG. 9 is a timing chart showing various signals used for printing operation; FIG. 10 is a timing chart showing pulse waveforms of heat enable signals; FIG. 11 is a block diagram showing a first modification in connection with a common use of the count lines; FIG. 12 is a block diagram showing a second modification in connection with a common use of the count lines; FIG. 13 is a block diagram showing a third modification in connection with a common use of the count lines; FIG. 14 is a block diagram showing a fourth modification in connection with a common use of the count lines; FIG. 15 is a block diagram showing a modification of an optimum heat enable signal generator; FIG. 16 is a block diagram showing the construction of the logic circuit of the conventional printhead; FIGS. 17A and 17B are block diagrams showing the relation between the conventional printhead and printing apparatus; and FIG. 18 is an explanatory view showing image data process executed in the conventional printing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiment of the present invention will now be described in detail in accordance with the accompanying drawings. First, the concept of the present invention will be described. <Concept of Invention> As it is understood from the conventional art, to perform stable printing operation, it is necessary to count the number of simultaneously-driven heat generators based on image data, and feed back the result of counting to drive pulse control, somewhere in a printing apparatus or printhead. FIGS. 1A and 1B are block diagrams showing the portion to count the number of heat generators simultaneously driven based on image data and the problem accompanying the counting. FIG. 1A shows the construction of an AND circuit to drive one heater driver (power transistor). FIG. 1B shows the arrangement of the AND circuits in the printhead. In the present invention, as shown in FIG. 1A, attention is focused on a signal line 1001 , which is turned ON when both image data (DATA) and a block selection signal (BLKi) as a time division signal are ON. The number of ON state signal lines 1001 is counted all over the printhead, and the count value is fed back for modulating a pulsewidth of a heat signal (HEAT). Accordingly, it is unnecessary to temporarily store the number of simultaneously-driven heat generators. This arrangement will be described in detail later. If the above idea is simply applied to manufacturing of circuit board, count lines must be provided corresponding to the number of the heat generators, as shown in FIG. 1 B. However, in a current printhead having 128, 256 or more heat generators, to provide a large number of count lines, a considerably large chip size is required. For example, in a printhead having 128 heat generators, if a width of 4 μm is required for an aluminum (Al) line and insulating space, a chip width of 4×128 μmm≅0.5 mm is required. Accordingly, the simple application of the above idea to board manufacturing results in deficiency in view of downsizing the apparatus and reducing production cost. Accordingly, in addition to the above idea, to reduce the area of the circuit board necessary to provide count lines, the present invention focuses attention on the fact that the maximum number of simultaneously-driven heat generators is the maximum number of heat generators which can be simultaneously driven in each time-division drive and the fact that each count line is turned OFF when time-division drive is not performed, and reduces the number of count lines. FIGS. 2A and 2B are block diagrams conceptually showing the reduction of the number of count lines. FIG. 2A shows the number of count lines which are turned ON in each time-division drive. FIG. 2B shows a construction where the count lines are commonly used, in consideration of the above-described maximum number of count lines which are turned ON upon each time-division drive. As it is understood from FIG. 2A, count lines 1001 a to 1001 c are not turned ON when a time division signal A (BLKA) is not ON, and the maximum number of ON lines is “3”. At this time, all the other count lines not driven by the time division signal A (BLKA) are turned OFF. Similarly, count lines 1001 d and 1001 e can not be turned ON except for a case where a time division signal B (BLKB) is ON, and the maximum number of ON lines is “2”. At this time, all the other count lines not driven by the time division signal B (BLKB) are turned OFF. Accordingly, the number of signal lines necessary to count the number of simultaneously-driven heat generators is the maximum number of heat generators belonging to each time-division section. As shown in FIG. 2B, as a count line belonging to different time-division sections is commonly used for counting in these sections, the number of count lines can be reduced while conflict of ON-state timing can be avoided. As a result, in FIG. 2A, only three count lines 1001 a to 1001 c are used. The commonly-used count lines as above are connected to an adder in the printhead. The adder counts the number of simultaneously-driven heat generators in real time. The result of counting is fed back to heat pulse signal modulation. FIG. 3 is a block diagram showing an example of the construction of a circuit which feeds back the number of simultaneously-driven heat generators to heat pulse signal modulation. In FIG. 3, the adder 104 , connected to the count lines 1001 a to 1001 c commonly used for counting, counts the number of simultaneously-driven heat generators, inputted from these lines, and outputs the result of addition to a heat signal selector 102 a . On the other hand, the heat signal selector 102 a inputs a plurality of heat pulse signals having predetermined different pulse widths. The heat signal selector 102 a selects one of the heat pulse signals in accordance with the result of addition inputted from the adder 104 , and uses the selected heat pulse signal as a drive pulse. When the printhead having the above construction is mounted on a printing apparatus, the relation between the printing apparatus and the printhead is as shown in FIG. 4 . That is, as the printing apparatus simply outputs a plurality of heat pulse signals having predetermined pulse widths generated by the drive pulse generator 803 , a circuit in consideration of the construction of the printhead can be omitted on the printing apparatus side. On the other hand, the printhead selects an appropriate heat pulse signal from the input plurality of heat pulse signals, based on the real-timely counted number of simultaneously-driven heat generators, thus enabling heat pulse width to be controlled independently of the printing apparatus. Hereinbelow, an embodiment to which the above concept of the present invention is applied will be described. First, the structure of a printer carrying a printhead which performs printing according to the present invention will be described. <Outline of Apparatus Main Body> FIG. 5 is a perspective view showing the structure of an ink-jet printer (hereinafter referred to as “printer”) IJRA as a representative embodiment of the present invention. In FIG. 5, a carriage HC is engaged with a spiral groove 5004 of a lead screw 5005 which rotates via drive force transmission gears 5009 to 5011 interlocking with forward/reverse rotation of a drive motor 5013 . The carriage HC has a pin (not shown) and is reciprocated in directions represented by arrows a and b held by a guide rail 5003 . The carriage HC has an ink-jet cartridge IJC which integrally comprises a printhead IJH and an ink tank IT. A paper holding plate 5002 presses a print sheet P against a platen 5000 along the moving direction of the carriage HC. Photocouplers 5007 and 5008 are home position detecting members for confirming the existence of lever 5006 of the carriage in this area and changing over the rotational direction of motor 5013 . A support member 5016 supports a cap member 5022 for capping the front surface of the printhead IJH. A suction member 5015 performs suction-restoration of the printhead through the inside of the cap member 5022 via a cap inner opening 5023 . Member 5019 allows a cleaning blade 5017 to move in a back-and-forth direction. A main body support plate 5018 supports the member 5019 and the cleaning blade 5017 . It is apparent that any well-known cleaning blade is applicable to the printer of the embodiment. Numeral 5021 denotes a lever for starting the suction operation of the suction-restoration. The lever 5021 moves along the movement of a cam 5020 engaged with the carriage HC. A well-known transmission mechanism such as change-over of a clutch controls a drive force from the drive motor. When the carriage HC is at the home position area, a desired one of these capping, cleaning and suction-restoration is executed at its corresponding position by the lead screw 5005 . The timing of any of these processings is not limited to the printer of the embodiment, if a desired processing is performed at a well-known timing. Further, in the ink-jet printer IJRA having the above structure, an automatic sheet feeder (not shown) is provided to automatically feed the print sheet P. <Construction of Controller> Next, the construction of a controller for executing print-control of the above printing apparatus will be described. FIG. 6 is a block diagram showing the construction of a controller of the ink-jet printer IJRA. Referring to FIG. 6 showing the control circuit, reference numeral 1700 denotes an interface for inputting a print signal; 1701 , an MPU; 1702 , a ROM for storing control programs executed by the CPU 1701 ; and 1703 , a DRAM for storing various data (the print signal, print data and the like supplied to the printhead). Reference numeral 1704 denotes a gate array (G. A.) for performing control on print data supply to the printhead IJH. The gate array 1704 also performs data-transfer control among the interface 1700 , the MPU 1701 , and the RAM 1703 . Reference numeral 1710 denotes a carrier motor for transferring the printhead IJH; 1709 , a conveyance motor for conveying the print sheet; 1705 , a head driver for driving the printhead IJH; and 1706 and 1707 , motor drivers for driving the conveyance motor 1709 and the carrier motor 1710 . The operation of the above control arrangement will be described below. When a print signal is input into the interface 1700 , the print signal is converted into print data for a printing operation between the gate array 1704 and the MPU 1701 . The motor drivers 1706 and 1707 are driven, and the printhead IJH is driven in accordance with the print data supplied to the head driver 1705 , thus performing the printing operation. <Internal Structure of Printhead IJH> FIG. 7 is a partially-cutaway perspective view showing the internal structure of the printhead IJH. In FIG. 7, numeral 100 denotes a circuit board holding a logic circuit; 500 , orifices for ink discharge; 501 , ink channels; 502 , a common ink chamber, communicating with the plurality of ink channels, for temporarily storing ink; 503 , an ink supply orifice which supplies ink from an ink tank (not shown); 504 , a top plate; 505 , liquid channel wall members which form the ink channels 501 when assembled with the top plate 504 ; 701 , heat generators; and 507 , wirings connecting the logic circuit to the heat generators 701 . The logic circuit, the heat generators 701 and the wirings 507 are formed by semiconductor manufacturing process on the circuit board 100 . The top plate holding the ink supply orifice 503 and the liquid channel wall members 505 are attached to the circuit board, thus constructing the printhead IJH. Then, ink supplied from the ink supply orifice 503 is stored in the internal common ink chamber 502 and supplied to the respective ink channels 501 . In this state, by driving the heat generators 701 , the ink is discharged from the discharge orifices 500 . <Construction of Logic Circuit of Printhead IJH> FIG. 8 is a block diagram showing the construction of the logic circuit of the printhead IJH. In FIG. 8, constituent elements corresponding to those in the conventional logic circuit in FIG. 16 have the same reference numerals, and explanations of the elements will be omitted. In the above-described concept of the present invention, in time-division drive of the printhead, regarding heat generators driven at different timings, the count line is commonly used. In an actual logic circuit, various circuits are used to input outputs from the count lines into the adder. In the example of FIG. 8, the output from an AND circuit 417 a is inverted by an inverter and pulled up. In FIG. 8, numerals 101 -( 1 ) to 101 -(k) denote input pads for inputting heat enable signals (HTSEL 1 to HTSELk) having different pulse widths supplied from the printer IJRA; 102 , a heat enable selector which selects one of the plurality of heat enable signals (HTSEL 1 to HTSELk); 103 , a comparator which outputs a signal to control the selected heat enable signal from the heat enable selector 102 ; 104 , the adder which adds the number of heat generators simultaneously-driven in time-division drive of the printhead, and outputs the result of addition to the comparator 103 ; and 105 , a memory for storing threshold data for comparison with the output from the adder 104 by the comparator 103 . Numeral 106 denotes m (=N/n) signal lines (count lines) used for determination of the number of simultaneously-driven heat generators; 107 , m pull-up resistors; and 108 , inverters of open-drain (or open-collector) output. The count lines 106 are connected to the adder 104 . As the inverters 108 are provided in correspondence with the respective AND circuits 417 a , N inverters 108 are provided in the logic circuit. The outputs from the inverters 108 are connected to the count lines 106 . As described above, in connection between the inverters 108 and the count lines 106 , the outputs from the AND circuits 417 a selected in the same block by the block selection signal (BLK 2 to BLKn) are not connected to the same count line 106 . By this connection, the maximum count value at the adder 104 is m (=N/n). Further, the respective count lines in the adder 104 are pulled up by the resistors 107 . According to the above construction, as the number of signal lines necessary to count the number of heat generators simultaneously driven by time-division drive and the possible count value can be N/n, the increase in the construction of the logic circuit can be suppressed. Next, drive control of the printhead having the above construction will be described in a case where the number of heat generators is 128 (N=128), the number of time division drive is 8 (n=8), the maximum number of simultaneously-driven heat generators is 16 (m=N/n=128/8), the number of heat enable signals is 4 (k=4), the number of count lines 106 is 16, and the heat enable signals (HTSEL 1 to HTSEL 4 ) are inputted into the input pads 101 -( 1 ) to 101 ( 4 ). Accordingly, in this example, the maximum count value of the adder 104 is “16”. On the other hand, three threshold values are stored in the memory 105 . The comparator 103 compares these threshold values with the count value (CNT) of the adder 104 . If 1≦CNT≦4 holds, the heat enable selector 102 selects the heat enable signal HTSEL 1 ; if 5≦CNT≦8 holds, the heat enable selector 102 selects the heat enable signal HTSEL 2 ; if 9≦CNT≦12 holds, the heat enable selector 102 selects the heat enable signal HTSEL 3 ; and if 13≦CNT≦16 holds, the heat enable selector 102 selects the heat enable signal HTSEL 4 . FIG. 9 is a timing chart showing various control signals used for drive control on the printhead. As is in the case of the conventional art, 128-bit image data (DATA) is inputted into the 128-bit shift register 404 in accordance with the clock (CLK). Further, the image data is stored into the 128-bit latch circuit 403 in accordance with the latch clock (LTCLK). Thereafter, the heat generators are driven based on the latched image data. As shown in FIG. 9, the 128 heat generators are divided into eight blocks each including 16 heat generators, and driven by the block selection signals (BLK 1 to BLK 8 ). In FIG. 9, numerals 1 to 128 are allotted to the 128 heat generators. The heat generators 1 to 16 are selected by the block selection signal BLK 1 ; the heat generators 17 to 32 are selected by the block selection signal BLK 2 ; and the heat generators 113 to 128 are selected by the block selection signal BLK 8 . As an example, FIG. 8 shows the heat generators surrounded by a broken-line, selected by the block selection signal BLK 1 as objects of time-division drive. Next, the four heat enable signals (HTSEL 1 to HTSEL 4 ) having different pulse widths are inputted from the printer IJRA via the input pads 101 -( 1 ) to 101 ( 4 ). As shown in FIG. 9, as the relation among the pulse widths of the heat enable signals, HTSEL 1 <HTSEL 2 <HTSEL 3 <HTSEL 4 holds. The number of heat generators simultaneously driven in each time-divisionally driven block (the number of simultaneously-driven heat generators) is determined based on the image data (DATA) latched by the 128-bit latch circuit 403 . In an example shown in FIG. 9, the numbers in the respective blocks are 2 , 16 , 9 , . . . , 6 . Under these conditions, the adder 104 adds the number of simultaneously-driven heat generators and outputs the result of addition into the comparator 103 . Then, the heat generators selected by the block selection signal BLK 1 are driven with the heat enable signal HTSEL 1 as a heat generator drive signal. The heat generators selected by the block selection signal BLK 2 are driven with the heat enable signal HTSEL 4 as a heat generator drive signal. The heat generators selected by the block selection signal BLK 3 are driven with the heat enable signal HTSEL 3 as a heat generator drive signal. Then, the heat generators selected by the block selection signal BLK 8 are driven with the heat enable signal HTSEL 2 as a heat generator drive signal. In this manner, the greater the number of simultaneously-driven heat generator becomes, the wider the pulse width supplied to the heat generators becomes. If the number of simultaneously-driven heat generators is large, the voltage drop due to the parasitic resistance is large, which reduces the voltage at both ends of the heat generator. To compensate the reduction of actual power supplied to the heat generators due to the voltage drop, the pulse width is increased so as to obtain uniform power. In the above description, specific numbers are employed as the number of heat generators, the number of heat enable signals (referred to as “level number”). Assuming that the pulsewidth of the heat enable signal is wider as the level number is greater, the relation between the simultaneously-driven heat generators and each level is in a general form as shown in Table 1. [TABLE 1] SIMULTANEOUSLY-DRIVEN HEAT LEVEL GENERATORS 1 1 to N/n 2 N/n + 1 to 2N/n . . . . . . i (i − 1) × N/n + 1 to i × N/n . . . . . . k (n − 1)N/n to N Further, as the count lines 106 connected to the adder 104 are pulled up, in data transferred on the count lines 106 , a period required for changing from an active state (“L”) to an inactive state (“H”) is longer than that required for changing from an inactive state (“H”) to an active state (“L”). Accordingly, it is desirable that the pulse waveforms of the heat enable signals have rising edges at the same timing, and have different falling edges, thus having different pulse widths, as shown in FIG. 10 . Assuming that an appropriate pulse width at level 1 is Pw( 1 ), the resistance value of one heat generator is R, and the parasitic resistance value that occurs on wiring related to the heat generator or power transistor is r, the pulse width at an arbitrary level (i) is expressed as follows: Pw ( i )=(2 Xr+R )· Pw ( 1 )/(2 r+R ) X =( i− 1)· N/k ( i<k ). In accordance with the above-described embodiment, a circuit which selects one of a plurality of heat enable signals based on the number of simultaneously-driven heat generators is provided on a logic circuit board of a printhead. In this arrangement, if a printer carrying the printhead simply supplies a plurality of heat enable signals having different pulse widths to the printhead, in the printhead, a heat enable signal having an optimum pulse width is automatically selected in accordance with image data in real time, and printing operation is performed. According to this arrangement, if the number of simultaneously-driven heat generators is small, since the voltage drop due to parasitic resistance is small, a heat enable signal having a relatively narrow pulse width is applied. On the other hand, if the number of simultaneously-driven heat generators is large, since the voltage drop due to parasitic resistance is large, a heat enable signal having a relatively wide pulse width is applied so as to compensate for power loss due to the parasitic resistance. Accordingly, even though the number of simultaneously-driven heat generators changes based on image data, approximately constant energy is supplied to the heat generators. Thus, a stable printing operation can always be performed. Further, this energy uniformization contributes to realization of a long life for the printhead. Further, as the printhead having the above-described construction does not use a clock synchronization circuit for a heat enable signal selection, printing operation is highly tolerant to noise. Furthermore, the circuit for heat enable signal selection can be formed in a layer under the wiring of the heat generators and power transistors and the like, of the logic circuit board, which conventionally has not been fully utilized for prevention of erroneous operation, together with these devices, by a semiconductor manufacturing process. In this case, the chip size is not substantially different from the conventional chip size. Further, the selection of heat enable signal having an optimum pulse width can be automatically performed within the printhead. In other words, the printing apparatus side does not have to be involved in the selection. The printing apparatus side simply transmits a plurality of heat enable signals having different widths to the printhead. Thus, it is not necessary for the printing apparatus to perform various control in accordance with the construction of the printhead as pointed out in the conventional techniques. Accordingly, the printing apparatus and the printhead can be designed and manufactured independently of each other except for matching between respective signal interfaces, and factors considered in design can be reduced. Note that in the above description, the number of heat generators is 128; however, the present invention is not limited to this number. The number of heat generators may be 256 or 512, for example. <Various Modifications in Connection with a Common Use of Count Lines> In the construction as shown in FIG. 8, the inverters 108 are provided between the AND circuits 417 a and the count lines 106 , and the count lines are pulled up, however, the present invention is not limited to this arrangement, but various modifications can be made. Hereinbelow, some of these modifications will be described. (1) First Modification FIG. 11 is a block diagram showing a first modification. In FIG. 11, the open-drain or open-collector output from the AND circuit 417 a is directly connected to the count line 106 , and the count line 106 is connected the ground by using a pull-down resistor 107 ′, thus pulled down. (2) Second Modification FIG. 12 is a block diagram showing a second modification. In FIG. 12, the output from the AND circuit 417 a is amplified via an OP amplifier 109 , and open-drain or open-collector output from the OP amplifier 109 is directly connected to the count line 106 . The count line 106 is connected to the ground, by using the pull-down resistor 107 ′, thus pulled down. In this arrangement, as an amplified signal is outputted onto the count line 106 , the voltage drop can be suppressed in a case where the distance from the contact of the count line 106 to the adder is long. (3) Third Modification FIG. 13 is a block diagram showing a third modification. In FIG. 13, the output from the AND circuit 417 a is directly connected to the count line 106 via a switch 110 comprising a diode or the like, and the count line 106 is connected to the ground by using the pull-down resistor 107 ′, thus pulled down. This arrangement prevents entrance of signal outputted onto the count line 106 from another AND circuit 417 a in an opposite direction by setting a threshold value of the switch 110 to a predetermined voltage value. (4) Fourth Modification FIG. 14 is a block diagram showing a fourth modification. In FIG. 14 having the same construction as that of FIG. 13, a bus terminator 111 is added to the end of the count line 106 so as to improve the drive performance with respect to the count line 106 . <Modification of Optimum Heat Enable Signal Generator> In the above-described embodiment, a plurality of heat enable signals having different pulse widths are inputted, and a heat enable signal having an optimum pulse width is selected, however, the present invention is not limited to this arrangement, but various modifications can be provided. That is, in place of the construction to input a plurality of heat enable signals and select one of these signals, a circuit which inputs a clock (CLK) used for image data (DATA) transfer and generates a plurality of heat pulse signals having different pulse widths based on the clock (CLK) may be provided in the printhead. Then, as described above, the comparator 103 compares the result of addition by the adder 104 with the threshold data stored in the memory 105 , and a heat enable signal having an optimum pulse width can be selected from the generated signals, based on the result of comparison. In this arrangement, as the pads for inputting the plurality of heat enable signals are omitted, the area of the circuit board can be reduced, thus the printhead circuit board can be downsized. Alternatively, as shown in FIG. 15, the printhead may have a heat signal generator 102 ′ which inputs the clock (CLK) used for image data (DATA) transfer and directly generates a heat enable signal having an optimum pulse width based on the clock (CLK) and the result of comparison by the comparator 103 between the result of addition by the adder 104 and the threshold data stored in the memory 105 . In the above-described embodiment, the printhead performs printing in accordance with an ink-jet method, however, the present invention is not limited to this printhead. The present invention is applicable to a printhead which performs printing in accordance with e.g. a thermal-transfer method or thermal printing method. However, the present invention can attain a high-density, high-precision printing operation by employing an ink-jet printer, which comprises means (e.g., an electrothermal transducer, laser beam generator, and the like) for generating heat energy as energy utilized upon execution of ink discharge, and causes a change in state of an ink by the heat energy, among the ink-jet printers. As the typical arrangement and principle of the ink-jet printing system, one practiced by use of the basic principle disclosed in, for example, U.S. Pat. Nos. 4,723,129 and 4,740,796 is preferable. The above system is applicable to either one of the so-called on-demand type or a continuous type. Particularly, in the case of the on-demand type, the system is effective because, by applying at least one drive signal, which corresponds to printing information and gives a rapid temperature rise exceeding nucleate boiling, to each of electrothermal transducers arranged in correspondence with a sheet or liquid channels holding a liquid (ink), heat energy is generated by the electrothermal transducer to effect film boiling on the heat acting surface of the printhead, and consequently, a bubble can be formed in the liquid (ink) in one-to-one correspondence with the drive signal. By discharging the liquid (ink) through a discharge opening by growth and shrinkage of the bubble, at least one droplet is formed. If the drive signal is applied as a pulse signal, the growth and shrinkage of the bubble can be attained instantly and adequately to achieve discharge of the liquid (ink) with the particularly high response characteristics. As the pulse drive signal, signals disclosed in U.S. Pat. Nos. 4,463,359 and 4,345,262 are suitable. Note that further excellent printing can be performed by using the conditions described in U.S. Pat. No. 4,313,124 of the invention which relates to the temperature rise rate of the heat acting surface. As an arrangement of the printhead, in addition to the arrangement as a combination of discharge nozzles, liquid channels, and electrothermal transducers (linear liquid channels or right angle liquid channels) as disclosed in the above specifications, the arrangement using U.S. Pat. Nos. 4,558,333 and 4,459,600, which disclose the arrangement having a heat acting portion arranged in a flexed region is also included in the present invention. In addition, the present invention can be effectively applied to an arrangement based on Japanese Patent Publication Laid-Open No. 59-123670 which discloses the arrangement using a slot common to a plurality of electrothermal transducers as a discharge portion of the electrothermal transducers, or Japanese Patent Publication Laid-Open No. 59-138461 which discloses the arrangement having an opening for absorbing a pressure wave of heat energy in correspondence with a discharge portion. Furthermore, as a full line type printhead having a length corresponding to the width of a maximum printing medium which can be printed by the printer, either the arrangement which satisfies the full-line length by combining a plurality of printheads as disclosed in the above specification or the arrangement as a single printhead obtained by forming printheads integrally can be used. In addition, an exchangeable chip type printhead which can be electrically connected to the apparatus main unit and can receive an ink from the apparatus main unit upon being mounted on the apparatus main unit can be applicable to the present invention as well as a cartridge type printhead in which an ink tank is integrally arranged on the printhead itself, as described in the above embodiment. It is preferable to add recovery means for the rinthead, preliminary auxiliary means and the like to the above-described construction of the printer of the present invention since the printing operation can be further stabilized. Examples of such means include, for the printhead, capping means, cleaning means, pressurization or suction means, and preliminary heating means using electrothermal transducers, another heating element, or a combination thereof. It is also effective for stable printing to provide a preliminary discharge mode which performs discharge independently of printing. Furthermore, as a printing mode of the printer, not only a printing mode using only a primary color such as black or the like, but also at least one of a multi-color mode using a plurality of different colors or a full-color mode achieved by color mixing can be implemented in the printer either by using an integrated printhead or by combining a plurality of printheads. Moreover, in each of the above-mentioned embodiments of the present invention, it is assumed that the ink is a liquid. Alternatively, the present invention may employ an ink which is solid at room temperature or less and softens or liquefies at room temperature, or an ink which liquefies upon application of a use printing signal, since it is general practice to perform temperature control of the ink itself within a range from 30° C. to 70° in the ink-jet system, so that the ink viscosity can fall within a stable discharge range. In addition, in order to prevent a temperature rise caused by heat energy by positively utilizing it as energy for causing a change in state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, an ink which is solid in a non-use state and liquefies upon heating may be used. In any case, an ink which liquefies upon application of heat energy according to a printing signal and is discharged in a liquid state, an ink which begins to solidify when it reaches a printing medium, or the like, is applicable to the present invention. In this case, an ink may be situated opposite electrothermal transducers while being held in a liquid or solid state in recess portions of a porous sheet or through-holes, as described in Japanese Patent Publication Laid-Open No. 54-56847 or 60-71260. In the present invention, the above-mentioned film boiling system is most effective for the above-mentioned inks. In addition, the ink-jet printer of the present invention may be used in the form of a copying machine combined with a reader and the like, or a facsimile apparatus having a transmission/reception function in addition to an image output terminal of an information processing apparatus such as a computer. The present invention can be applied to a system constituted by a plurality of devices (e.g., a host computer, an interface, a reader and a printer) or to an apparatus comprising a single device (e.g., a copying machine or a facsimile apparatus). As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

A printhead with a comparatively simple construction, which contributes to reducing the cost of the entire system and development work, effectively utilizes essential constituent devices of a logic circuit of the printhead such as a shift register, while omitting control on the printing apparatus side, and individually performs stable print operation, while suppressing variation of energy inputted to heat generators due to voltage drop by parasitic resistance. A printing apparatus incorporates the printhead. The printhead has a counter which counts the number of simultaneously-driven heat generators, which always changes in accordance with image data, based on externally-inputted image data and block selection signal, and a modulator which modulates the pulse width of a drive signal applied to the simultaneously-driven heat generators based on a value obtained from counting by the counter.

BACKGROUND OF THE INVENTION The present invention relates to automobile security equipment, particularly to anti-theft devices for automobiles. The prior art includes various security devices for automobiles which effectively disable the steering wheel by preventing its turning. Such prior steering wheel disabling devices may be divided into two general classes. The first includes steering wheel locking devices which comprise steering column interlocking or engaging components. Such prior devices are typically mechanically or electro-mechanically interconnected to the automobile ignition locking system. The second general classification of prior steering wheel locking devices includes those devices which comprise removable mechanical steering wheel engaging elements which come into movement-limiting contact with a fixed member of the automobile. The present invention is of the latter general classification of steering wheel locking devices. Chen (U.S. Pat. No. 5,199,283) discloses an automobile steering lock which, in many ways, is typical of prior removable steering wheel-engaging security devices. The Chen device is popularly known and marked under the trade name "THE CLUB". Although these prior devices are advertised to prevent or deter automobile theft, such devices have several short-comings and, in many cases, have failed in this endeavor. Most prior removable steering wheel-engaging security devices, such as the Chen device, comprise a rigid elongated portion and locking means for temporarily securing the rigid elongated portion to the steering wheel. The locking portion typically involves a lock and key set, and openable jaws which are adapted to engage the rim of the steering wheel. The rigid elongated portion typically comprises a hard metallic bar, or the like, which extends well beyond the rim of the steering wheel. When properly installed (i.e. locked into place) onto the rim of a steering wheel, the elongated bar prevents full and safe rotation of the steering wheel because, depending upon the design of the elongated portion and the make of the automobile, the elongated bar comes into a fixed member of the automobile (eg. the window, the door, the dash board, the windshield, etc.). Clearly, proper operation of such prior devices depends on (1) the adequacy of the locking portion to tightly secure to the steering wheel rim, and (2) the strength of the elongated portion. Accordingly, such prior devices typically have over-designed, excessively strong locks, and have elongated portions constructed of excessively strong metal or composite materials. Largely overlooked with prior removable steering wheel-engaging security devices is that, in order to defeat or bypass such devices, it is only necessary to cut (i.e. saw) the steering wheel rim at the point of attachment to the locking member. For example, in order to defeat the elongated steering wheel locking device of Chen (U.S. Pat. No. 5,199,283) it is only necessary to make one (or, at the most, two) small cuts in the rim of the steering wheel. Once the rim of the steering wheel is cut, the locking device is quite easily removed and the automobile can readily be steered. It will be appreciated by those skilled in the art that such prior removable steering wheel-engaging security devices can be defeated in such a manner, totally independent of the strength of lock or the hardness of the elongated portion. SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a removable steering wheel-engaging security device which significantly and materially lessens the probability of the theft of an automobile. Another object of the present invention is to provide a device of the character described which is easily visible from the exterior of a vehicle, and which may deter a potential thief from attempting to steal the vehicle equipped with this invention on its steering wheel. Yet another object of the invention is to provide an apparatus of the character described that is not cumbersome, easy to use, and is inexpensive in relation to its benefits. Another object of the present invention is to provide a removable steering wheel-engaging security device which provides greater anti-theft deterrence than prior devices, by preventing physical access to a steering wheel surface. Another object of the present invention is to provide a removable steering wheel-engaging security device which prevents the removal of the device and protects the steering wheel from cutting, by way of hack saw, by denying a thief access to the surface of the steering wheel. Another object of the present invention is to provide a removable steering wheel-engaging security device which provides a simple detachable device which is easily carried and stored within the vehicle and is easy to manufacture. These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the present invention shown installed on an automobile steering wheel; FIG. 2 is a plan view of one form of the invention as shown in FIG. 1; FIG. 3 is a side view of the security rod hook flanges located on the side apron of the invention; FIG. 4 is front elevation of the present invention shown installed on an automobile steering wheel; FIG. 5 is a top view of the present invention installed on an automobile steering wheel, shown in partial cross-section; FIG. 6 is a side view of the invention as placed in its fixed position on a steering wheel; and FIG. 7 shows the present invention mounted on a steering wheel of an automobile. DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 through 6, there is shown a rigid metal housing, or "shield" (generally designated (50) in the drawings), having a shield body (22) which is positioned in front of, and encompasses, the surface of a steering wheel (W), and a side apron (14) which extends around the side of the steering wheel (W). The shield body (22) has a predetermined configured opening (32) which is designed to allow manual access to a tubular security rod member (26) for placement on the steering wheel (W) and to facilitate adjustment of the telescopic security rod member (30). The shield opening (32) can be shaped, or configured to accommodate any style steering wheel, including, but not limited to, flat to convex configurations to accommodate any steering wheel configuration, including, but not limited to steering wheels with airbags. A pair of security rod hump housings (24) are integrally formed on the shield body (22). The security rod hump housings are located at diametrically opposed positions on the face of the shield body (22). An adjustable telescopic security rod member (48) extends through both hump housings (24) and traverses the center of the shield body (22). The telescopic security rod member (48) comprises a first telescopic security rod member (30) telescopically engaged with a second tubular security rod member (26). Each telescopic security rod member extends through one of the hump housings. The adjustable security rod member (48) is immovable, and neither the telescopic security rod member (30) nor the tubular security rod member (26) can be removed or separated from their respective hump housings (24). The tubular security rod member (26) and the telescopic security rod member (30) have single welded steel security rod hooks (10) connected and attached at the diametrically opposed ends of the shield security rod members (26) and (30), respectively. A hand grip 40 is installed on the free end of the telescopic security rod member (30). The telescopic security rod member 30, when extended to its maximum position on the steering wheel (W), allows the diametrically opposed security rod hooks (10) to snugly engage under the bottom, or under-surface of the steering wheel (W). The security rod hooks (10) will then insert themselves into the hook flange catches (12) which are located at diametrically opposed positions on the shield body's side apron (14). The telescopic security rod member (48) may be optimally extended on the steering wheel (W), by manually gripping the knurled hand grip (42) on the tubular security rod member (26), which is longitudinally connected to the telescopic security rod member (30) as shown in FIG. 6. The telescopic security rod member (48) will automatically lock in place by means of any well known locking mechanism (36) for locking a pair of telescoping tubular rods. In the preferred embodiment of the invention the telescopic security rod member (30) is long enough that, in operation, it extends sufficiently outboard of the rim of the steering wheel (W) to come into contact with a fixed member of the automobile (such as the door, or the dashboard, or the floor, or the windshield, etc.) when the steering wheel is turned. The locking mechanism (36) can be configured and placed in any appropriate location on either the tubular security rod member (26) or on the telescopic security rod member (30). The shield body (22) and its apron (14) are preferably constructed of a rigid metal, (such as steel), since the strength of this device is of paramount importance. It will be understood from the foregoing description that a device constructed in accordance with the present invention provides a rigid metal anti-theft shield body (22) having an accurately contoured apron (14) with two diametrically opposed welded, or fixed hook flange catches (12), which, when placed on a steering wheel (W) completely covers the surface, rim, and periphery of the steering wheel. The telescopic security rod member (30) and the tubular security rod member (26) together provide an immovable, albeit adjustable, security rod which together are designated as (48) in the drawings. This encased, immovable, adjustable steel security rod (48) traverses horizontally through the center of the shield body (22), and same is encased within security rod hump housings (24) that are designed to allow longitudinal (i.e. axial) telescopic movement of the telescopic security rod member (30). The security rod (48) is connected to the steering wheel (W) by single welded steel hooks (10), which are attached at diametrically opposed ends of the security rod (48). A configured access, or opening (32) in the center surface face of the shield body (22) is designed to allow manual access to the security rod (48) for its placement on the steering wheel (W), and to telescopically extend the hooks (10) into the shield body's hook flange catches (12). A mesh surface (42) is provided on the security rod (48) to facilitate manual gripping of the security rod. Once fully extended, the diametrically opposed hooks (10) on the security rod (48) engage snugly under the bottom surface of the steering wheel (W), and then are inserted into the hook flange catches (12) located on the shield body's side apron (14), by telescopically extending the security rod (48) which automatically engages the security rod locking mechanism (36) after extending to its maximum position on the steering wheel (W). Once the shield (50) is securely fixed on the steering wheel (W), it will be readily apparent to any potential automobile thief that the vehicle will be too difficult, and, more importantly, too time consuming to attempt a theft of the vehicle, or to remove the shield (50) to gain access to the steering wheel in order to operate the vehicle. In particular, because the shield 50 completely surrounds the front and side of the steering wheel, it would be readily apparent to any potential automobile thief that the security device made in accordance with the present invention could not be removed from the steering wheel, for example, by simply making one or two saw cuts through the steering wheel's rim. Although the description above contains the material specification of the invention, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of the presently preferred embodiment of the invention. For example, the shield body (22) can be of several shapes other than circular, such as square, oval, concave, etc., the shield body's hook flanges located on the shield body's side apron (14), which engage the telescopic security rod hooks can have other shapes and locations on the shield body's side apron (14), and can be more than two as specified in the present invention, the shield body's aperture, or opening (32), can be any shape, or configuration, such as circular, oval, trapezoidal, square, rectangular, etc., to accommodate a particular steering wheel design; the metal shield (50) can be constructed of any rigid metal or combination metal/fiberglass composition, or other materials to provide the necessary body strength of the shield body (22) and the shield body's side apron (14). Additionally, the security rod hump housings (24) may be of any configuration, such as square, round or concave, etc., and can be either flush with the surface of the shield body (22), or encased in any depth within said shield body, consistent with the operation and adjustment of the telescopic security rod. Further, the number of security rod hooks, and their shape, or configuration, and the location, or position of the hooks on the telescopic security rod may vary in the invention. The telescopic security rod shape can be round, square or of any specified length, weight or predetermined configuration consistent with the hump housings (24) which will accommodate the adjustment of the telescopic security rod (30), and which will secure the shield 50 to a steering wheel (W). In addition, the locking means mechanism on the invention's telescopic security rod can be of any size, means or location on the security rod, or on the shield body, or a combination of both, consistent with the intended purpose of the invention to secure and fix the housing enclosure to a steering wheel, and to render the steering wheel unaccessible. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.

An anti-theft device for attachment to a steering wheel of an automobile, has a continuous metal shield, having a shield body which is accurately shaped to completely cover the top surface of the steering wheel and a shield body's side apron which is accurately shaped to completely surround the outer periphery of the steering wheel. The metal shield is configured to encase an elongate rigid security rod in diametrically opposed hump housings located on the face of the shield body. A pair of opposing hooks engage the rim of the steering wheel when the elongate rigid security rod is telescopically extended. Hook flanges extending from the underside of the shield body's apron engage the two hooks. A keyed lock secures the device to the steering wheel. Access to the keyed lock is provided by an access opening in the center of the shield body.

RELATED APPLICATION This application is a continuation-in part application of U.S. application Ser. No. 10/229,274, entitled “Use of Multiple Antioxidant Micronutrients as Systemic Biological Radioprotective Agents” which was filed on Aug. 28, 2002 now U.S. Pat. No. 7,449,451 and has now been granted a Notice of Allowance and is related to U.S. Provisional Application No. 60/315,522, filed Aug. 29, 2001, entitled “Use of Multiple Antioxidant Micronutrients as Systemic Biological Radioprotective Agents”. BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a use of micronutrient formulations to reduce the effects of radiation on humans. Description of the Related Art Ionizing radiation (X-rays and gamma rays) has proven to be a double-edged sword in clinical Medicine since its discovery by Dr. Wilhelm Roentgen in 1895 (1,2). Energy wavelength progresses along the electromagnetic continuum from longer ranges (radiowaves, microwaves, infrared, and heat waves) to medium wavelengths (visible light, ultraviolet light) to shorter wave lengths (ionizing radiation, e.g., x-rays and gamma rays). It is these x-rays and gamma rays that are able to drive electrons out of their normal atomic orbits with enough kinetic energy to generate charged molecules (including free radicals) that damage cells. In addition to the initial realization by the medical community that ionizing radiation could detect as well as treat human diseases, came the unfortunate demonstration that it could also induce serious illness. In fact, most of the ionizing radiation to which the human population is exposed, other than that received from environmental sources, is from the diagnostic and screening imaging machines employed by today's clinical healthcare professionals. For example, in the past, x-ray-induced skin cancers were noted with higher frequency in radiologists. Obviously, whenever x-rays are employed, it is done with caution so that patients and healthcare providers are exposed to as low a does as possible. Physicists and nuclear engineers have devised improved equipment and radiation beam delivery systems to reduce the level of diagnostic radiation dose without compromising the quality of images. However radiation biologists agree that there is no threshold dose below which there is no risk of cellular damage. In fact, even a single radiation track that crosses a cellular nucleus has a very low, but finite, probability of generating damage that may result in cellular dysfunction, somatic and heritable mutations, and subsequent genetic implications. While most clinical radiologists believe the risks of x-ray exposure are very small, residual biologic effects from alteration in structure are dependent on whether the cell repairs its injured components. Although the vast majority of damage is repaired, some may be unrepaired or misrepaired and there in lies the problem. In adults, most radiation researchers consider cancer induction to be the most important somatic effect of low dose ionizing radiation and this outcome may occur in nearly all the tissues of the human body. Academic radiologists are also raising future disease concerns regarding pediatric age groups because of the increased numbers of imaging studies now being performed in younger populations (3). In light of these concepts the healthcare profession states that ionizing radiation exposure should only occur when there is a defined healthcare benefit, or indicated when the risk-benefit ratio is favorable to the patient. The critical concept has been always to protect humans by physical local factors, such as shielding and decreasing doses and x-rays times. However, no one has previously considered the additional aspects to a strategy of systemic biological protection. Recent advances in imaging technology have made possible the detection of many illnesses such as heart disease, cancer, neurologic diseases, arthritis and other acute or chronic conditions. It is also significant development that this technology may detect the problem at an early stage when treatment interventions allow for less invasive therapeutic procedures and/or surgical operations and yet achieve improved health outcomes. In this environment, the number of diagnostic x-rays performed is truly enormous. It was estimated in the United States for the period 1985 to 1990 at least 800 diagnostic studies per 1,000 population were performed and this excluded dental x-rays and nuclear medicine (4). The importance of these finding can be appreciated since it is probable that frequent low dose radiation exposures may be more damaging than a single higher dose exposure on the criteria of gene mutations and cancer promotion. The current era has seen an explosion of diagnostic imaging equipment including the introduction of computed tomography, digital radiography, expanded nuclear medicine applications, interventional radiology, and lengthening fluoroscopic procedures. In concert with these technical innovations, the concept of early disease detection and screening large populations to employ illness prevention strategies will generate further rapid expansion of members of imaging studies with increased ionizing radiation exposure to the public. As a direct consequence of this new proactive healthcare approach, imaging will be performed in many more, otherwise healthy, people and asymptomatic “at risk” populations. In addition, initial exposures will occur at an earlier age and the mandate of serial follow-up imaging will result in an overall greater frequency of x-ray studies. The doses of ionizing radiation exposure in imaging studies vary dramatically from less than 0.1 rem (1 millisievert, mSv, for x-rays and gamma rays, 1 rem=1 rad) per test for some procedures to others that involve levels in some organs in excess of 10 rem per test. Table 1 lists a sampling of common studies (5-8). Note that while the red marrow dose is usually the reported “standard”, the actual target organ dose is actually often significantly higher. For example, mammography exposes the actual breast tissue to approximately 700 mrem, virtually equal to the total skin entrance dose. Likewise, thallium scanning exposes the thorax to approximately 1000 mrem, about 20 times the red marrow dose. TABLE 1 Skin Effective Dose Entrance Equivalent (HE) Dose Procedure mSv* mrem mrem Diagnostic X-ray Chest AP, 100 kVp 0.015 1.5 10 Lumbar spine AP, 80 kVp 0.273 27.3 359 Upper G.I. 4.1 410  2300/min Coronary angioplasty 50-150/min 5000-15000/ 25000/min min Head CT 0.8-5    80-500 4500 Abdomen CT  6-24  600-2400 2000 Dental 0.01 1 350 Electron beam CT heart 0.14-0.3  14-30 150 Mammogram ** ** 700 mSv mrem mrem Nuclear medicine 18F-Fluorodeoxyglucose, 9.99 999 NA 10 mCi 99 mTc-MAA Lung Scan 2.03 203 NA (perfusion only) 5 mCI 99 mTc-HDP Bone scan 20 mCi 5.92 592 NA 201 TI Thallium scan 3 mCi 25.53 2553 NA *Seivert is the official unit of biological radiation dose. One Sv = 100 rem. ND = Data not available ** = Dose negligible NA = Not Applicable Depending on the age of the individual, frequency of testing, exposure time, and total dose, the diagnostic or screening imaging studies could increase the risk of somatic damage (some forms of cancer such as leukemia, breast, and thyroid) as well as genetic damage (such as with gonadal exposure) in the target population. In fact, radiation experts are beginning to call for special attention to issues of exposure from CT Scanning in young patients (9). It should be emphasized that the risk of radiation injury produced by diagnostic doses below 0.5 rem is very small in comparison to other agents that are present in the diet of the natural environment. However, regardless of the “insignificant” risk with any individual exposure or imaging event, the total effects of ionizing radiation are on-going, cumulative over time, have the potential for lifelong expression, and may have a future generational genetic impact. It should be anticipated that as more sophisticated imaging studies are available for diagnosis and screening, the individual small risks may add up over a lifetime. For example, nuclear medicine has been expanded to new techniques which include intravenous systemic injection of radionuclides and expose various body organs to differing radiation doses (10). The recent impact of interventional techniques often combined with surgical procedures also increases the imaging risks. Furthermore, advance fluoroscopic imaging used for technical procedures such as percutaneous transluminal angioplasty, transhepatic cholangiography, stent and drainage placements as well as venous access procedures may involve significant radiation exposure (11). In fact by the year 2000 in the United States alone, about 750,000 patients underwent coronary balloon angioplasty (12). Finally, the most recent technical innovations utilized in screening procedures, such as spiral and electron beam computed tomography for heart, lung, colon, and total body scanning are new clinical areas where issues of radiation dosimetry have to be considered (13,14). Currently, the FAA and airlines consider flight personnel (including flight attendants) as radiation workers. As such, they are allowed a regulatory dose limit 50 times the dose limit allowable to the general public. According to recent estimates, over 400,000 frequent fliers travel over 75,000 air miles each year, which means that they will exceed radiation dose limits to the general public from galactic (cosmic) radiation during flight (15). The radiation exposure during flight varies with altitude, flight time, air route, and solar flare activity. As an example, a routine flight form New York to Chicago (highest altitude 37,000 feet) yields a radiation dose rate of 0.0039 mSv per block hour. (The block hour begins when the aircraft leaves the blocks before takeoff and ends when it reaches the blocks after landing.) A flight from Athens, Greece to New York (highest altitude 41,000 feet) yields a radiation dose rate of 0.0063 mSv per block hour. The total radiation dose from the New York to Chicago route is 0.0089 mSv and the Athens t New York flight is 0.0615 mSv. For reference, the annual exposure limit for the general public is 1 mSv. The only remediation recommended by the FAA for radiation exposure during fight to is to limit flight and avoid traveling during periods of increased solar flare activity. Airline crew members flying long-haul high-altitude routes receives, on average, greater exposure each year than do radiation workers in ground-based industries where radioactive sources or radiation-producing machines are used (16). The United States military is aware of and concerned about potential radiation exposures to out troops. Perhaps the most obvious population risk in the military is pilots flying long, high-altitude missions. The expected radiation doses would be in accordance with the estimates outlined above. The most recent U.S. Army study on the issue recognizes four nuclear radiation exposure risk categories of military personnel based on their likelihood and extent of exposure (17, Table 2). The army currently has three radiation protection programs to address these risk categories. One is applied to those individuals whose duties parallel those of civilian radiation workers. These include military personnel, such as x-ray technicians, radiologists who do radiological examinations, researchers who use radionuclides, and technicians who maintain radioactive commodities, such as radiation detection instruments and calibration sources. The second applies to soldiers whose primary occupation does not usually expose them to radiation. These are soldiers who might respond to a military situation, such as that covered by Allied Command Europe Directive (ACE) 80-63, in which radiation is present, but at doses not exceeding 700 mSv. The third category applies to those situations involving extremely high radiation exposure, such as nuclear war. TABLE 2 Revised, Low-Level Radiation Guidance for Military Operations Radiation Increased Total Exposure Risk of Cumulative State Recommended Long Term Dose* Category Actions Fatal Cancer** <0.5 mGy 0 None None 0.5-5 mGy 1A Record individual 1:4,000 dose readings Initiate periodic monitoring 5-50 mGy 1B Record individual 1:400   dose readings Continue monitoring Initiate rad survey Prioritize tasks Establish dose control measure as part of operations 50-100 mGy 1C Record individual 1:200   dose readings Continue monitoring Update survey Continue dose-control measures Execute priority tasks only*** 100-250 mGy 1D Record individual 1:80    dose readings Continue monitoring Update survey Continue dose control measures Execute critical tasks only**** 250-700 mGy 1E Record individual 1:30    dose readings Continue monitoring Update survey Continue dose control measures Execute critical tasks only *The use of the measurement millisievert is preferred in all cased. However, due to the fact that normally the military has only the capability to measure milligray (mGy), to the fact that normally the military has only the capability to measure milligray (mGy), as long as the ability to obtain measurement in millisievert is not possible, U.S. forces will use milligray. For whole body gamma irradiation, 1 mGy is equal to 1 mSv. All doses should be kept as low as reasonably achievable (ALARA). This will reduce the risk to individual soldiers and will retain maximum operational flexibility fur future employment of exposed soldiers. **This is in addition to the 1:5 and 1:4 incidence of fatal cancer among the general population. Increased risk is given of induction of fatal cancer (losing an average) of 24 years of life for personnel ages 20-20 years). It must be noted that higher radiation dose rates produce proportionately more health risks than the same total dose given over a long period. ***Examples of priority tasks are those missions to avert danger to persons or to prevent damage from spreading. ****Examples of critial tasks are those missions required to save lives. *The use of the measurement millisievert is preferred in all cased. However, due to the fact that normally the military has only the capability to measure milligray (mGy), as long as the ability to obtain measurement in millisievert is not possible, U.S. forces will use milligray. For whole body gamma irradiation, 1 mGy is equal to 1 mSv. All doses should be kept as low as reasonably achievable (ALARA). This will reduce the risk to individual soldiers and will retain maximum operational flexibility fur future employment of exposed soldiers. **This is in addition to the 1:5 and 1:4 incidence of fatal cancer among the general population. Increased risk is given of induction of fatal cancer (losing an average of 24 years of life for personnel ages 20-30 years). It must be noted that higher radiation dose rates produce proportionately more health risks than the same total dose given over a longer period. ***Examples of priority tasks are those missions to avert danger to persons or to prevent damage from spreading. ****Examples of critical tasks are those missions required to save lives. This study committee made four recommendations: 1) When making decisions, commanders should consider the long-term health effects that any action may have on their troops. This recommendation was extended such that it became standard operating policy. 2) The U.S. Department of Defense should develop and clearly express an underlying philosophy for radiation protection. Specifically, the committee suggested, a. application and adaptation of the system recommended by the International Commission of Radiological Protection, b. in peacetime or nonemergency situations, soldiers should be accorded the same level of protection accorded civilians, and c. in settings in which an intervention is required and specific numerical dose limits are neither applicable nor practical, commanders should justify the mission (there is more benefit than risk), examine competing risks, and optimize the mission (identify way to minimize dose without jeopardizing the mission). 3) Military personnel should receive appropriate training in both radiation effects and protection. Their training will need to vary on the basis of the particular level of potential exposure and the task at hand. 4) A program of measurement, recording, maintenance, and use of dosimetry and exposure information is essential. The programs, once again, include no protection measures other than controlling time, distance, and physical shield. Radiation workers experience a broad spectrum of working conditions that have radiation exposure as a normal part of the workplace environment. Examples include medical radiology workers, nuclear power plant workers, and worker who use radiation and radioactive materials in research. As mentioned above, commercial flight crews are also considered to be radiation workers. Owing to this occupational classification, radiation workers are allowed to receive 50 times the radiation dose allowed to the general public. Radiation workers also differ from the general public in that they receive training about the risks of radiation exposure and are monitored for their radiation exposure as part of their working paradigm. The nuclear regulatory commission (NRC) has established occupational dose limits as noted previously and procedures for monitoring and record-keeping. These standards and regulations rely solely on time, distance, and physical shielding as methods of radiation protection. SUMMARY OF THE INVENTION The present invention provides a formulation consisting essentially of: Vitamin A (palmitate) 5,000 I.U. Natural mixed carotenoids 15 mg Vitamin D-3 (cholecalciferol) 400 I.U. Natural soucre Vitamin E (d-alpha tocopherol) 100 I.U. (d-alpha tocopheryl acid succinate) 100 I.U. Buffered Vitamin C (calcium ascorbate) 500 mg Thiamine mononitrate 4 mg Riboflavin 5 mg Niacinamide ascorbate 30 mg d-calcium pantothenate 10 mg Pyridoxine hydrochloride 5 mg Cyanocobalamin 10 μg Folic Acid (Folacin) 800 μg D-Biotin 200 μg Selenium (1-seleno-methionine) 100 μg Chromium picolinate 50 μg Zinc glycinate 15 mg Calcium citrate 250 mg Magnesium citrate 125 mg Plus a booster formulation selected from a group consisting essentially of 1000 mg of vitamin C, 400 international units of d-alpha tocopheryl acid succinate, 200 international units of alpha tocopherol, 500 mg of N-acetyl cysteine, 50 mg of natural mixed carotenoids, and 100 mg of alpha lipoic acid, wherein said formulation is designed to reduce the risk in humans exposed to ionizing radiation of becoming subjected to at least one condition selected from the group consisting essentially of radiation-induced acute leukemia, breast cancer, thyroid cancer and other somatic and heritable mutations. In another embodiment, the dosage is taken prior to anticipated exposure. In yet another embodiment, the dosage is taken after exposure. In still another embodiment, the formulation is taken by user after exposure for a period of at least seven days. In still yet another embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 0.5 mSv or less. In a further embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 0.5-5 mSv. In yet a further embodiment, the formulation is designed for a human who receives internal radionuclide exposures. In still a further embodiment, the formulation consisting essentially of antioxidants, said antioxidants are selected from the group consisting essentially of vitamin C, vitamin E, N-acetyl cysteine, natural mixed carotenoids, and alpha-lipoic acid, vitamin A (palmitate), vitamin D-3 (cholecalciferol), thiamine mononitrate, riboflavin, niacinamide ascorbate, d-calcium pantothenate, pyridoxine hydrochloride, cyanocobalamin, folic acid, D-Biotin, selenium (1-seleno-methionine), chromium picolinate, zinc glycinate, calcium citrate and magnesium citrate and mixtures thereof; and plus a booster formulation selected from a group consisting essentially of vitamin C, d-alpha tocopheryl acid succinate, alpha tocopherol, N-acetyl cysteine, natural mixed carotenoids and alpha lipoic acid, said formulation is designed to reduce the risk in humans exposed to doses of ionizing radiation of becoming subjected to at least one condition selected from the group consisting essentially of radiation-induced acute leukemia, breast cancer, thyroid cancer and other somatic and heritable mutations. In yet a further embodiment, the formulation comprises at least one glutathione elevating agent. In still a further embodiment, the dosage level of antioxidants is proportionate to the radiation level exposed to by a human. In still yet a further embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 0.5 mSv or less. In another further embodiment, the antioxidants consist essentially of 250 mg of vitamin C, 200 international units of d-alpha acid succinate, and 250 mg of N-acetyl cysteine and the complete dosage is taken 1 hour prior to imaging study. In yet another embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 0.5-5 mSv In still another embodiment, the antioxidants consist essentially of 500 mg of buffered vitamin C, 400 international units of d-alpha tocopheryl acid succinate, 250 mg of N-acetyl cysteine, 15 mg of natural mixed carotenoids, and 30 mg of alpha-lipoic acid and a complete dosage is taken 1 hour prior to an imaging study. In still yet another embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 5-15 mSv. In another embodiment, the antioxidants consist essentially of 500 mg of buffered vitamin C, 400 international units of d-alpha tocopheryl acid succinate, 250 mg of N-acetyl cysteine, 15 mg of natural mixed carotenoids, and 30 mg of alpha-lipoic acid and a complete dosage is taken 24 hours and 1 hour prior to an imaging study and 24 hours after the imaging study. In yet another embodiment, the formulation is designed for a human who receives an effective dose of ionizing radiation of 15-250 mSv. In still another embodiment, the antioxidants consists essentially of 500 mg of buffered vitamin C, 400 international units of d-alpha tocopheryl acid succinate, 500 mg of N-acetyl cysteine, 30 mg of natural mixed carotenoids, and 60 mg of alpha lipoic acid and a complete dosage is taken 48 hours, 24 hours and 1 hour prior to imaging study and 24 hour after imaging study. In yet another embodiment, the antioxidants consist essentially of: Vitamin A (palmitate) 3,000 I.U.-10,000 IU Natural mixed carotenoids 10 mg-50 mg Vitamin D-3 (cholecalciferol) 400 I.U.-1000 IU Natural soucre Vitamin E (d-alpha tocopherol) 50 IU-400 I.U. (d-alpha tocopheryl acid succinate) 50 IU-400 I.U. Buffered Vitamin C (calcium ascorbate) 250 mg-2000 mg Thiamine mononitrate 2 mg-20 mg Riboflavin 3 mg-30 mg Niacinamide ascorbate 20 mg-60 mg d-calcium pantothenate 5 mg-50 mg Pyridoxine hydrochloride 5 mg-50 mg Cyanocobalamin 5 mcg-50 mcg Folic Acid (Folacin) 200 mcg-1600 mcg D-Biotin 50 mcg-400 mcg Selenium (1-seleno-methionine) 50 mcg-400 mcg Chromium picolinate 50 mcg-200 mcg Zinc glycinate 10 mg-30 mg Calcium citrate 100 mg-500 mg Magnesium citrate 50 mg-200 mg In still yet another embodiment, the booster formulation consist essentially of: 200-2000 mg of vitamin C, 100-800 international units of d-alpha tocopheryl acid succinate, 100-800 international units of alpha tocopherol, 100-500 mg of N-acetyl cysteine, 10-50 mg of natural mixed carotenoids, and 15-100 mg of alpha lipoic acid. In a further embodiment, the present invention provides for a method of manufacturing a formulation, said method comprising admixing antioxidants, said antioxidants consist essentially of: Vitamin A (palmitate) 3,000 I.U.-10,000 IU Natural mixed carotenoids 10 mg-50 mg Vitamin D-3 (cholecalciferol) 400 I.U.-1000 IU Natural soucre Vitamin E (d-alpha tocopherol) 50 IU-400 I.U. (d-alpha tocopheryl acid succinate) 50 IU-400 I.U. Buffered Vitamin C (calcium ascorbate) 250 mg-2000 mg Thiamine mononitrate 2 mg-20 mg Riboflavin 3 mg-30 mg Niacinamide ascorbate 20 mg-60 mg d-calcium pantothenate 5 mg-50 mg Pyridoxine hydrochloride 5 mg-50 mg Cyanocobalamin 5 mcg-50 mcg Folic Acid (Folacin) 200 mcg-1600 mcg D-Biotin 50 mcg-400 mcg Selenium (1-seleno-methionine) 50 mcg-400 mcg Chromium picolinate 50 mcg-200 mcg Zinc glycinate 10 mg-30 mg Calcium citrate 100 mg-500 mg Magnesium citrate 50 mg-200 mg In another further embodiment, the method further comprises preparing a booster formulation, said method comprises admixing said booster formulation consisting essentially of: 200-2000 mg of vitamin C, 100-800 international units of d-alpha tocopheryl acid succinate, 100-800 international units of alpha tocopherol, 100-500 mg of N-acetyl cysteine, 10-50 mg of natural mixed carotenoids, and 15-100 mg of alpha lipoic acid. In yet another further embodiment, the formulation and the formulation booster are designed to reduce the risk in humans exposed to doses of ionizing radiation of becoming subjected to at least one condition selected from the group consisting essentially of radiation-induced acute leukemia, breast cancer, thyroid cancer and other somatic and heritable mutations. In another embodiment, the booster formulation is first prepared being admixed with said formulation. In still another embodiment, the said formulation and the booster formulation are combined together and provided to the patient together. In yet another embodiment, the formulation and the booster formulation are prepared separately and provided to the patient separately. In one further embodiment, the present invention provides for a micronutrient formulation, the formulation comprises: a first composition comprising alpha tocopherol and derivative esters of alpha tocopherol, the derivative esters of alpha tocopherol being selected from a group consisting essentially of alpha tocopheryl acetate, alpha tocopheryl palmitate, alpha tocopheryl succinate, alpha tocopheryl nicotinate and mixtures thereof; a second composition comprising vitamin A and natural-mixed carotenoids; and a third composition comprising calcium ascorbate. For purposes of this invention, natural-mixed carotenoids are defined as a natural extract of the algae species Dunaliella salina , the majority of which is beta carotene that contains various other natural carotenoids present in smaller amounts. In a further embodiment, the method of the present invention wherein the percentage of each composition is as follows: the first composition is from about 1 to about 50% of the formulation; the second composition is from about 1 to about 50% of the formulation; and the third composition is from about 1 to about 50% of the formulation. In another embodiment, the formulation further comprises a fourth composition, and the fourth composition is selected from a group consisting essentially of B-vitamins, selenium, zinc, magnesium, chromium and mixtures thereof. In yet another embodiment, the first, second, third and fourth compositions function as dietary micronutrients. For purposes of this invention, the term “dietary micronutrients” are defined as nutrients, including but not limited to vitamins and minerals that are consumed through the diet in small amounts and are distinct from dietary macronutrients which are defined as fats, proteins and carbohydrates. Dietary micronutrients include, but are not limited to tocopherols and tocopheryl esters (Vitamin E), Vitamin A, Vitamin C, Vitamin D, B-Vitamins, selenium, calcium, magnesium, zinc, carotenoids (e.g. beta carotene), and chromium. In still another embodiment, the calcium ascorbate in the third composition is a source of vitamin C. In still yet another embodiment, the formulation further comprises a fifth composition, and the fifth composition is selected from a group consisting essentially of alpha lipoic acid, co-enzyme Q10, L-carnitine, n-acetyl cysteine and mixtures thereof. In a further embodiment, the fifth composition functions as an endogenous micronutrient. For purposes of this invention, the term “endogenous micronutrients” are defined as nutrients that are normally produced by the body. Due to factors such as aging, disease, physical activity level and environmental stressors, optimal amounts of these endogenous micronutrients may no longer be present in the body and need to be provided through supplementation. Endogenous micronutrients can be included in dietary supplements from synthetic or natural sources. Endogenous micronutrients include, but are not limited to lipoic acid, N-acetyl cysteine, nicotinamide adenine dinucleotide (NADH), l-carnitine, and coenzyme Q10. In another further embodiment, the formulation further comprises reduced nicotinamide adenine dinucleotide. In yet a further embodiment, the present invention provides for a micronutrient formulation system, the system comprises: a first composition comprising alpha tocopheryl and derivative esters of alpha tocopherol, the derivative esters of alpha tocopherol being selected from a group consisting essentially of alpha tocopheryl acetate, alpha tocopheryl palmitate, alpha tocopheryl succinate, alpha tocopheryl nicotinate and mixtures thereof; a second composition comprising vitamin A and natural-mixed carotenoids; a third composition comprising calcium ascorbate; a fourth composition selected from a group consisting essentially of B-vitamins, selenium, zinc, magnesium, chromium and mixtures thereof; and a fifth composition selected from a group consisting essentially of alpha lipoic acid, co-enzyme Q10, L-carnitine, n-acetyl cysteine and mixtures thereof, wherein said formulation is without iron, copper and manganese. In still a further embodiment, the formulation system of the present invention wherein the first composition is from about 1 to about 50% of the formulation; the second composition is from about 1 to about 50% of the formulation; the third composition is from about 1 to about 50% of the formulation; the fourth composition is from about 1 to about 50% of the formulation; and the fifth composition is from about 1 to about 50% of the formulation. In still yet a further embodiment, the formulation system of the present invention is consumed by the user at least twice per day. In another further embodiment, the present invention provides for a method of manufacturing a micronutrient formulation comprising: admixing a first composition comprising alpha tocopheryl and derivative esters of alpha tocopherol, and the derivative esters of alpha tocopherol being selected from a group consisting essentially of alpha tocopheryl acetate, alpha tocopheryl palmitate, alpha tocopheryl succinate, alpha tocopheryl nicotinate and mixtures thereof; and then admixing a second composition comprising vitamin A and natural-mixed carotenoids; and then admixing a third composition comprising calcium ascorbate; and then admixing a fourth composition comprising selected from a group consisting essentially of B-vitamins, selenium, zinc, magnesium, chromium and mixtures thereof; and then admixing with a fifth composition selected from a group consisting essentially of alpha lipoic acid, co-enzyme Q10, L-carnitine, n-acetyl cysteine and mixtures thereof. In one embodiment, the individual compositions are first admixed or combined and then the first composition is admixed with the second and then the first and second compositions are then admixed with the third composition; then the first second and third mixed compositions are then admixed with the fourth composition and then the fifth composition is admixed at the end. In another embodiment, the compositions are all admixed together. In still another embodiment, the compositions can be added in any random order. In a further embodiment, the method of the present invention wherein the percentage of each composition is as follows: the first composition is from about 1 to about 50% of the formulation; the second composition is from about 1 to about 50% of the formulation; the third composition is from about 1 to about 50% of the formulation; the fourth composition is from about 1 to about 50% of the formulation; and the fifth composition is from about 1 to about 50% of the formulation. In a further embodiment, the method of the present invention wherein the percentage of each composition is as follows: the first composition is from about 1 to about 30% of the formulation; the second composition is from about 1 to about 30% of the formulation; the third composition is from about 1 to about 20% of the formulation; the fourth composition is from about 1 to about 20% of the formulation; and the fifth composition is from about 1 to about 20% of the formulation. In another further embodiment, the method of the present invention further comprises admixing reduced nicotinamide adenine dinucleotide. In yet another embodiment, the formulation is consumed twice a day. In still yet another embodiment, the formulation is without iron, copper and manganese. In a further embodiment, the formulation is designed to prevent excess production of free radical environment by the administration of said formulation to a patient. In another further embodiment, the present invention relates to a micronutrient formulation comprises: a first composition comprising Vitamin A, Vitamin C, Vitamin E and natural mixed carotenoids; and a second composition comprising lipoic acid. In yet a further embodiment, the formulation further comprises a third composition, and the third composition is selected from a group consisting essentially of co-enzyme Q10, L-carnitine, n-acetyl cysteine and mixtures thereof. In still a further embodiment, the formulation is consumed by the user at least twice per day. If it could be possible to devise a strategy to reduce the potential adverse effects of radiation exposure, it certainly seems reasonable that this approach should be undertaken regardless of how small the actual risk of injury might be. Federal law by regulatory code (C.F.R. 21 and C.F.R. 35) emphasizes ALARA guidelines as they relate to occupational radiation exposure. This concept should be extended to the biological consequences of the doses received by all classes of exposed individuals, including patients. The guidelines could be referred to as DALARA (damage as low as reasonably achievable), whereby both the dose and its harmful consequences could be minimized without interfering with the efficacy, ease, or cost of diagnostic procedures, or occupational and other activities. This novel concept, supported by extensive data, is based on reducing radiation-derived free radical damage by antioxidant supplementation. Special attention needs to be given to population groups under chronic risk situations like frequent fliers, radiation workers, flight crews, and military personnel in combat theatres of operation. In such cases, episodic dosing with antioxidants is not adequate to achieve ALARA principles. These population groups should achieve and maintain higher antioxidant loads than person with little or no expectation of radiation exposure. In accordance with the present invention, twice daily dosing with a properly designed multiple antioxidant formulation is employed to maintain desired antioxidant loads in the body. When chronically exposed (or chronic risk of exposure) individuals can be reasonably expected to incur an acute exposure, such as dangerous combat missions or any flight operations, they should supplement their regular antioxidant regimen with additional doses of selected antioxidants to protect against the anticipated exposure. More particularly, the present invention is directed to a method for protecting humans in need of such protection from physical damage caused by ionizing radiation comprising administering to said humans on a defined basis prior to and after exposure to such radiation a plurality of antioxidants at a dosage level directly proportional to the radiation level likely to be encountered. DETAILED DESCRIPTION OF THE INVENTION As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various forms. The examples disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. Although brief medical x-rays themselves may not cause detectable damage, serial imaging, future screening studies (the importance of which cannot be currently predicted), flight exposures, military operations exposures, occupational exposures, and other factors, such as diet, disease status, and environmental exposure, and the like may be clinically significant. Relevant findings from basic scientific studies underscore this clinical concern. For example, a dose of 2 rem does not cause detectable mutations in normal human lymphocytes in culture. However, if the cells are irradiated with the same dose and treated with caffeine for a few hours after radiation exposure, an increased rate of cellular mutations is observed. This suggests that radiation-induced changes could be repaired in the normal course of events, but that subsequent exposure to caffeine impairs this normal cellular protective mechanism. In addition, a radiation dose that by itself would not be sufficient to induce cancer in an in vitro experimental system is able to do so in the presence of tumor promoters, such as phorbol ester, estrogen, and others. Furthermore, x-rays increase the incidence of cancer in cell culture by several folds when combined with chemical carcinogens, certain DNA viruses, ultraviolet radiation, or ozone exposure. Clearly, the potential hazard of even small radiation doses should not be ignored, since the target population readily interacts with agents present in the diet and environment, as well as other factors present in individual lifestyles. Risk Categories The following risk categories are general guidelines only and refer to acute exposures. The examples listed are not totally inclusive. The actual risk for any particular person may be modified by age and health status. The actual designation for all persons should be determined by healthcare or radiation physics professionals. Population groups experiencing chronic radiation exposure risk, such as radiation workers (including commercial and military flight crews and field combat personnel), should maintain a higher baseline antioxidant load by taking a multiple antioxidant formulation (SEVAK) two times a day. They should then take the appropriate radioprotective formulation when the acute risk of exposure is expected (daily necessary). Categories 2-4 are equivalent with respect to formulation and can be regarded to be adequate for exposures less than 15 sMv effective dose when used for acute exposures only. Category 1: Effective Dose 0.5 mSv or less For example: chest x-ray, dental x-ray, abdominal x-ray, skeletal plain films, most commercial flight passengers. Category 2: Effective Dose 0.5-5 mSv For example: diagnose/screening computed tomography, urologic imaging, mammography, flight crews (commercial and military) and other radiation workers. Category 3: Internal Radionuclide Exposures For example: radionuclide imaging. Category 4: Effective Dose 5-15 mSv For example: limited diagnostic fluoroscopy (upper GI series, cholangiography, brain enema). Category 5: Effective Dose Greater Than 15 mSv-250 mSv For example: prolonged fluoroscopy/interventional radiology (coronary angiography, cerebral angiography, transluminal angioplasty) and some military personnel in combat operations (ground troops and seamen). Category 6: Effective Dose 1000-2000 mSv For example: radiation workers, civilian populations at risk near nuclear reactor sites in the event of an accident, and at risk military personnel in overseas theatres of operation. Category 7: Effective Dose greater than 2000 mSv (not exceeding bone marrow syndrome doses) For example: radiation workers, civilian populations at risk near nuclear sites in the event of an accident, and at risk military personnel in overseas theatres of operation. Hereinafter, the term “imaging study” will be employed to include chest x-ray, dental x-ray, abdominal x-ray, skeletal plain films, diagnostic/screening computed tomography, urologic imaging, mammography, radionuclide imaging, limited diagnostic fluoroscopy, prolonged fluoroscopy/interventional radiology and the like. The specific example below will enable the invention to be better understood. However, they are given merely by way of guidance and do not imply any limitation. Example 1 Baseline Formulation (SEVAK) Vitamin A (palmitate) 5,000 I.U. Natural mixed carotenoids 15 mg Vitamin D-3 (cholecalciferol) 400 I.U. Natural source Vitamin E (d-alpha tocopherol) 100 I.U. (d-alpha tocopheryl acid succinate) 100 I.U. Buffered Vitamin C (calcium ascorbate) 500 mg Thiamine mononitrate 4 mg Riboflavin 5 mg Niacinamide ascorbate 30 mg d-calcium pantothenate 10 mg Pyridoxine hydrochloride 5 mg Cyanocobalamin 10 μg Folic acid (Folacin) 800 μg D-Biotin 200 μg Selenium (1-seleno methionie) 100 μg Chromium picolinate 50 μg Zinc glycinate 15 mg Calcium citrate 250 mg Magnesium citrate 125 mg Radioprotective Formulations: (Boost Formulations) Example 2 For Category 1 Personnel Vitamin C (calcium ascorbate) 250 mg Natural source vitamin E 200 I.U. (d-alpha tocopheryl acid succinate) N-acetyl cysteine 250 mg Example 3 For Category 2 Personnel Vitamin C (calcium ascorbate) 500 mg Natural source vitamin E 400 I.U. (d-alpha tocopheryl acid succinate) N-acetyl cysteine 250 mg Natural mixed carotenoids 15 mg Alpha lipoic acid 30 mg Complete dosage to be taken 1 hour prior to an imaging study or prior to each flight. Example 4 For Category 3 Personnel Vitamin C (calcium ascorbate) 500 mg Natural source vitamin E 400 I.U. (d-alpha tocopheryl acid succinate) N-acetyl cysteine 250 mg Natural mixed carotenoids 15 mg Alpha lipoic acid 30 mg Complete dosage to be taken 1 hour prior to an imaging study and 24 hours and 48 hours after the imaging study. Example 5 For Category 4 Personnel Vitamin C (calcium ascorbate) 500 mg Natural source vitamin E 400 I.U. (d-alpha tocopheryl acid succinate) N-acetyl cysteine 250 mg Natural mixed carotenoids 15 mg Alpha lipoic acid 30 mg Complete dosage to be taken 24 hours and 1 hour prior to an imaging study 24 hours after the imaging study. Example 6 For Category 5 Personnel Vitamin C (calcium ascorbate) 500 mg Natural source vitamin E 400 I.U. (d-alpha tocopheryl acid succinate) N-acetyl cysteine 500 mg Natural mixed carotenoids 30 mg Alpha lipoic acid 60 mg Complete dosage to be taken 48 hours, 24 hours and 1 hour prior to an imaging study 24 hours after the imaging study. Example 7 For Category 6 Personnel Vitamin C (calcium ascorbate) 1000 mg d-alpha tocopheryl acid succinate 400 I.U. alpha tocopherol 200 I.U. N-acetyl cysteine 500 mg Natural mixed carotenoids 40 mg Alpha lipoic acid 100 mg Complete dosage to be taken prior to anticipated exposure or as soon as possible after actual exposure. Continue complete dosage daily for seven days after exposure. Example 8 For Category 7 Personnel Vitamin C (calcium ascorbate) 2000 mg d-alpha tocopheryl acid succinate 600 I.U. alpha tocopherol 200 I.U. N-acetyl cysteine 1000 mg Natural mixed carotenoids 50 mg Alpha lipoic acid 150 mg Complete dosage to be taken prior to anticipated exposure or as soon as possible after actual exposure. Continue complete dosage daily for seven days after exposure. It has been estimated that approximately 70-80% of the cellular damage induced by ionizing radiation is caused by free radicals. Therefore, it would be prudent to use agents that would quench these substances formed during x-ray exposure and protect the cells, organs, and total body from such injury. Since World War II, extensive studies have been undertaken- to identify radioprotective compounds that have been shown to be effective when administered before exposure to irradiation. It is important to note that such compounds do not protect cells or organisms if they are administered after the ionizing radiation exposure. For modest radiation dose levels, the protective agents can be absorbed rapidly enough that they could be effective when given immediately before the exposure (within an hour or two). For enough levels of radiation dosage, it might be more desirable to achieve an established steady state of antioxidant concentration in the tissues initially, an then provide a booster dose of radioprotective agent immediately prior to exposure. Research has determined that sulfhydryl (SH) compounds such as cysteamine, cystamine, and glutathione are among the most important and active intracellular antioxidants. Cysteamine protects animals against bone marrow and gastrointestinal radiation syndromes. The rationale for the importance of SH compounds is further supported by observations in mitotic cells. These are the most sensitive to radiation injury in terms of cell reproductive death and are noted to have the lowest level of SH compounds. Conversely, S-phase cells, which are the most resistant to radiation injury using the same criteria, have demonstrated the highest levels of inherent SH compounds. In addition, when mitotic cells were treated with cysteamine, they became very resistant to radiation. It has also been noted that cysteamine may directly protect cells against induced mutations. Unfortunately, cysteamine is extremely toxic when administered to human beings and, therefore, cannot itself be utilized in a radioprotective antioxidant regimen. Thus, other SH compounds sharing the same antioxidant characteristics must be considered. Glutathione is a very effective antioxidant. However, when ingested by human beings it is completely hydrolyzed in the intestine and, therefore, can not be used as a radioprotective agent. However, N-acetylcysteine (NAC) and alpha lipoic acid actively increase the intracellular levels of glutathione without causing any toxicity. These rapidly absorbed compounds are tolerated by humans very well and would provide protection against ionizing radiation damage when given prior to the exposure. Indeed, these agents have also been shown to be of radioprotective value in experimental systems. Additional antioxidants such as vitamin E (d-alpha tocopheryl succinate), vitamin C (as calcium ascorbate) and the carotenoids (particularly natural beta-carotene) have been shown to be of marked radioprotective value in animals and in humans. A very recent report by the Armed Forces Radiobiology Research Institute showed good protection by vitamin E against lethal doses of cobalt-60 in mice. The natural beta-carotene was selected because it most effectively reduces radiation-induced transformation in mammalian cells in culture. The d-alpha tocopheryl succinate form of vitamin E was selected because it is the most effective form of this micronutrient and also actively reduces the incidence of radiation-induced transformation in mammalian cells. This form of vitamin E is a more effective antioxidant than the more commonly utilized alpha tocopherol or other mixtures of tocopherols. Vitamin C as calcium ascorbate is beneficial because it is the most effective nonacidic form available for human use and, therefore, is less likely to cause stomach upset, diarrhea, and other problems that are observed in some individuals when taking therapeutic doses of vitamin C. The most effective antioxidant approach to the free radical damage related to ionizing radiation-induced injury must utilize multiple micronutrients. It has been determined that multiple antioxidants are more effective than the individual agents themselves, and we propose this approach for several reasons. It is known that vitamin C and vitamin E are synergistic as antioxidants against free radicals because they are able to protect both the aqueous and lipid environments of the cells respectively. Indeed, one study has shown that oral intake of both vitamin C and vitamin E reduces the levels of fecal mutagens formed during digestion more than that produced by either of the individual antioxidants. It also must be recognized that oxygen level may vary widely within the tissues of whole organs or within the individual cells. This is especially true during the biologic insults that may occur with radiation-induced damage. It is known that beta-carotene acts more effectively as an antioxidant in high oxygen pressures, whereas vitamin E is a more effective antioxidant at reduced oxygen pressures. Finally the body produces several types of free radicals (a myriad of oxygen-derived and nitrogen-derived species) during exposure to ionizing radiation. Clearly, each antioxidant has a different affinity for each specific class of free radicals. In a parallel manner, a combination of antioxidants is more effective in reducing the growth of tumor cells than the individual agents themselves. Therefore, to provide the most effective overall micronutrient approach to protect against radiation injury, a multiple component protocol utilized with a risk-based strategy seems essential and rational. Most commercially available multiple supplement formulations contain iron, copper, and/or manganese. It is well known that these substances actively generate free radicals when combined with vitamin C. In addition, these minerals are more easily absorbed from the intestinal tract in the presence of antioxidants, such as vitamin C, and thereby increase the body stores of these minerals. Increased iron stores have been associated with many chronic human conditions, including heart disease, cancer and neurological diseases. Therefore, the addition of iron, copper or manganese to any multiple antioxidant preparation has no scientific merit for optimal health or disease prevention. Only in cases where a person has iron-deficiency anemia is a short-term iron supplement essential. Many commercially available preparations contain heavy metals such as boron, vanadium, zirconium and molybdenum. Sufficient amounts of these metals are obtained from the diet and the daily consumption of excess amounts over long periods of time can be neurotoxic. Many commercial preparations contain inositol, methionine and choline in varying amounts, e.g., 30 mg to 60 mg. These small doses serve no useful purpose for improving health because 400 mg to 1,000 mg of these nutrients are obtained daily from even the most minimal diet. Para-aminobenzoic acid (PABA) is present in some multiple vitamin preparations. PABA has no biologic function in mammalian cells and can block the antibacterial effect of sulfonamides. Therefore, the effectiveness of a sulfonamide may be reduced in some patients being treated for bacterial infection. Commercially sold multiple antioxidant preparations often contain varying amounts of N-acetyl cysteine or alpha lipoic acid. These nutrients are utilized because they are known to increase glutathione levels in cells. Reduced glutathione is a powerful antioxidant and actively protects both normal and cancer cells against radiation damage. Many cancer patients take antioxidant supplements without the knowledge of their oncologists. Therefore, the consumption of antioxidant preparations containing N-acetyl cysteine or alpha lipoic acid by these patients undergoing radiation therapy could interfere with important anti-cancer treatment. The addition of both natural mixed carotenoids and vitamin A to any multiple vitamin preparation is essential, because beta-carotene not only acts as a precursor of vitamin A, but also performs important biological functions that cannot be performed by vitamin A. Beta-carotene increases the expression of the connexin gene, which codes for a gap junction protein that is necessary for maintaining the normal cellular phenotype. While other carotenoids, such as, lycopene, xanthophylls, and lutein, are also important for health, they can be obtained from an adequate diet with tomato (lycopene), spinach (lutein), and paprika (xanthophylls) in amounts are higher than those that can be supplied from supplements. Therefore, the addition of a few milligrams of lycopene, xanthophylls, and lutein to any multiple vitamin preparation serves no useful purpose for health or disease prevention. The proper ratio of two forms of vitamin E, d-alpha tocopherol, which is normally present in the body, and d-alpha succinate, to a multiple antioxidant preparation is essential. Alpha tocopheryl succinate is the most effective form of vitamin E inside the cells, where as alpha tocopherol can readily act as an antioxidant in the intestinal tract and in the extracellular environment of the body. Alpha-tocopherol at doses of 20-60 μg/ml can stimulate the immune system, while the beta, gamma, and delta forms at similar doses can inhibit the immune system. This effect of these forms of tocopherol may not be related to their antioxidant action and, since they are less effective than alpha tocopherol, their supplementation is not recommended. Tocotrienols are also antioxidants, but they may inhibit cholesterol synthesis. Since this activity is not beneficial in healthy individuals, prolonged consumption of tocotrienols as a supplement is not optimal. Vitamin C is usually administered as ascorbic acid, which can cause stomach upset, diarrhea and other complications in some individuals. However, using the calcium ascorbate form is most suitable because it is non-acidic and has not been shown to produce negative side effects. The use of potassium ascorbate and magnesium ascorbate in any vitamin preparation is unnecessary. Also, any multiple micronutrient preparation should include adequate amounts of B-vitamins (2-3 times of RDA) and appropriate minerals. The risk of chronic illness may depend upon the relative consumption of protective versus toxic substances. If the daily intake of protective substances is higher than toxic agents, the incidence of chronic illness may be reduced. Since we know very little about the relative levels of toxic and protective substances in any diet, a daily supplement of micronutrients including antioxidants would assure a higher level of preventive protection. The present invention also provides for the following formulation examples: Example 9 Bioshield—R1 in Two Capsules Vitamin C (calcium ascorbate) 500 mg d-alpha tocopheryl succinate 400 IU Natural mixed carotenoids 15 mg Selenomethionine 100 mcg n-acetylcysteine 250 mg Alpha-lipoic acid 30 mg Example 10 Bioshield—R2 in Four Capsules Daily Vitamin A (as palmitate) 5,000 Vitamin C (as calcium ascorbate) 1,000 mg Vitamin E (as d-alpha-tocpheryl succinate) 200 IU (as d-alpha-tocopherol) 200 IU Vitamin D (as cholocalciferol) 400 IU Vitamin B-1 (thiamine mononitrate) 4 mg Vitamin B-2 (riboflavin) 5 mg Niacin (as niacinamide ascorbate) 30 mg Vitamin B-6 (as pyrodioxine HCl) 5 mg Folate (Folic acid) 800 mcg Vitamin B-12 (as cyanocobalamin) 10 mg Biotin 200 mcg Pantothenic acid (as d-calcium pantothenate) 10 mg Calcium citrate 250 mg Magnesium citrate 125 mg Zinc (as zinc glycinate) 15 mg Selenium (as selenomethionine) 200 mcg Chromium (as chromium picolinate) 50 mcg Coenzyme Q10 30 mg N-acetylcysteine 250 mg Alpha-lipoic acid 30 mg Natural mixed carotenoids 15 mg Example 11 Bioshield—R3 in Six Capsules/Daily Vitamin A (as palmitate) 5,000 Vitamin C (as calcium ascorbate) 1,000 mg Vitamin E (as d-alpha-tocpheryl succinate) 400 IU (as d-alpha-tocopherol) 200 IU Vitamin D (as cholocalciferol) 400 IU Vitamin B-1 (thiamine mononitrate) 4 mg Vitamin B-2 (riboflavin) 5 mg Niacin (as niacinamide ascorbate) 30 mg Vitamin B-6 (as pyrodioxine HCl) 5 mg Folate (Folic acid) 800 mcg Vitamin B-12 (as cyanocobalamin) 10 mg Biotin 200 mcg Pantothenic acid (as d-calcium pantothenate) 10 mg Calcium citrate 250 mg Magnesium citrate 125 mg Zinc (as zinc glycinate) 15 mg Selenium (as selenomethionine) 200 mcg Chromium (as chromium picolinate) 50 mcg Coenzyme Q10 30 mg N-acetylcysteine 500 mg Alpha-lipoic acid 90 mg Natural mixed carotenoids 60 mg Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the attendant claims attached hereto, this invention may be practiced otherwise than as specifically disclosed herein.

A radioactive protection micronutrient formulation system is provided and the system comprises: a formulation consisting essentially of antioxidants, the antioxidants are selected from the group consisting essentially of vitamin C, vitamin E, N-acetyl cysteine, natural mixed carotenoids, and alpha-lipoic acid, vitamin A (palmitate), vitamin D-3 (cholecalciferol), thiamine mononitrate, riboflavin, niacinamide ascorbate, d-calcium pantothenate, pyridoxine hydrochloride, cyanocobalamin, folic acid, D-Biotin, selenium (1-seleno-methionine), chromium picolinate, zinc glycinate, calcium citrate and magnesium citrate and mixtures thereof; and plus a booster formulation selected from a group consisting essentially of vitamin C, d-alpha tocopheryl acid succinate, alpha tocopherol, N-acetyl cysteine, natural mixed carotenoids and alpha lipoic acid, the formulation is designed to reduce the risk in humans exposed to doses of ionizing radiation of becoming subjected to at least one condition selected from the group consisting essentially of radiation-induced acute leukemia, breast cancer, thyroid cancer and other somatic and heritable mutations.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image-forming optical system used for a projection type image display apparatus such as a projector and an image pickup apparatus such as a camera. 2. Description of the Related Art A projection type image display apparatus displays an image by illuminating an image display element such as a liquid crystal panel or digital micro mirror device with luminous flux from a light source and enlarging/projecting transmitted light or reflected light modulated by the image display element on a screen, etc. using a projection lens. FIG. 4 shows a projection optical system disclosed in International Publication No. WO97/01787, which relates to patents to be republished. In this optical system, luminous flux emitted from a light source 101 a is reflected by reflection mirrors such as illumination optical systems 101 b , 101 c and 101 d and incident upon a reflection type image display panel 102 . Then, the luminous flux modulated and reflected by the image display panel 102 is reflected by mirrors 103 a , 103 b , 103 d , 103 e and a flat mirror 103 f which are capable of image-forming, and diagonally projected onto a screen 104 . On the other hand, various image-forming optical systems using a decentered optical system aiming at miniaturization of the entire optical system have been recently proposed. A decentered optical system introduces a concept called a “reference optical axis” and can construct an optical system with aberration sufficiently corrected by forming a rotationally asymmetric aspherical surface or so-called free form surface. For example, Japanese Patent Laid-Open No. 9-5650 proposes the design method and Japanese Patent Laid-Open No. 8-292371 and Japanese Patent Laid-Open No. 8-292372 propose design examples thereof. When an off-axial optical system, that is, a reference optical axis along the ray penetrating the center of an object (or the center of an image) and the center of the pupil is considered, this decentered optical system is defined as an optical system including an off-axial curved surface where the plane normal at the intersection with the reference optical axis of the configured surface is not on the optical axis and is referred to as an optical system with a folded reference optical axis. This optical system, by appropriately configuring, prevents eclipse even on the reflecting surfaces, and therefore it is easier to construct an optical system using the reflecting surfaces. The off-axial optical system also features the ability to route optical paths relatively freely. Furthermore, using a reflection image-forming optical system only using surface curved mirrors makes it possible to remove almost all influences of chromatic aberration which is a problem of a refractor system. In a projection optical system disclosed in International Publication No. WO97/01787 shown in FIG. 4 , reflectors 103 a , 103 b , 103 d and 103 e having image-forming action in particular are constructed of rotationally symmetric aspherical reflectors having a common rotation axis and images are diagonally projected using the reflectors of these concave mirrors and convex mirrors partially. However, there are restrictions on the degree of freedom, such that the surfaces should have a common axis, and therefore there are limitations to correcting aberration and brightening the reflection optical system (reducing the F number). Furthermore, according to this projection optical system, luminous flux that has passed through an aperture-stop 103 c is incident upon a convex mirror 103 b and the divergent luminous flux from this convex mirror 103 b is incident upon the next convex mirror 103 d . For this reason, the effective diameter of the convex mirror 103 d has a tendency to increase. In this way, the distance between the reflectors of the projection image-forming optical system constructed by combining a plurality of mirrors tends to increase and the problem is that the size of the entire apparatus increases. With regard to an image projection apparatus, a projection apparatus generally uses a transmission type liquid crystals for the image display panel. Furthermore, as an image-forming optical system used for the projection apparatus, almost all products use refraction lenses under actual circumstances. In the image-forming optical system used with this transmission type liquid crystal panel device, it is well known that the object, which is the image display panel, needs to have a telecentric optical configuration in order to improve light utilization efficiency. Though it depends on the specification of the product, the projection image-forming optical system is generally required to be brighter than F3.0 in order to reduce the load on the illumination optical system, reduce costs and power consumption and provide optimal apparatus performance. When an image-forming optical system constructed by combining a plurality of curved reflection mirrors is used instead of a projection image-forming system using refraction lenses, the off-axial optical system is characterized in that the off-axial optical system can set the projection angle (projection angle of elevation) high (large) more easily than the refraction optical system. However, designing the refraction optical system with high projection angles requires an extremely wide angle of view, which results in a problem that the design becomes more difficult and the diameter of lenses increases. Constructing an optical system by only combining surface reflection mirrors with a hollow configuration per se has an advantage of preventing influences of chromatic aberration, etc. However, attempting to apply an image-forming optical system combining curved reflection mirrors as the projection image-forming optical system meeting requirements of the projection apparatus using the above-described liquid crystal panel involves the following problems. In the case of a lens, which is brighter than F3.0 on the image display panel side, it is unavoidable that the effective diameter of the first mirror on the object side increases. Furthermore, as described above, since the object side is telecentric, points from which spread luminous flux is emitted in the direction perpendicular to the surface of the object are arranged side by side with the height of the object corresponding to the size of the image display panel as object points, and the effective diameter of the first mirror unavoidably increases all the more. This results in a problem that the size of the entire optical system increases. SUMMARY OF THE INVENTION It is an object of the present invention to provide a compact image-forming optical system used for a projection type image display apparatus and image pickup apparatus capable of projecting at a high angle of elevation when used, for example, for a projection type image display apparatus and also brightening the F number. In order to attain the above-described object, an image-forming optical system of the present invention, provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, when an optical path is traced from a first conjugate point which is nearer to a second conjugate point which is farther, in order starting with the first conjugate point, comprises the following elements. That is, the image-forming optical system comprises a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux, and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Then, the following condition should be satisfied: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]  (1) where ξ is an absolute value of an angle formed by the normal line of the first mirror and a reference axis at an intersection of the reference axis and the first mirror, the reference axis is an optical path along which a central ray of the luminous flux from the first conjugate point progresses, η is an absolute value of an angle formed by the normal line of the second mirror and the reference axis at an intersection of the reference axis and the second mirror, and F is an effective F number on the first conjugate point side. Furthermore, an image-forming optical system of the present invention, provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, when an optical path is traced from a first conjugate point which is nearer to a second conjugate point which is farther, in order starting with the first conjugate point, comprises the following elements. That is, the image-forming optical system comprises a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Then, the following condition should be satisfied: 2.3≧2 ×L 1 ×sin η/Φ 1 ≧1.1  (2) Φ 1 = L 0 ′/ F+P   (3) where P is a size of a conjugate surface which has a predetermined size and includes the first conjugate point within the meridional cross section, the meridional cross section is a flat plane including a reference axis which has been folded by the first and second mirrors, the reference axis is an optical path along which a central ray of the luminous flux from the first conjugate point progresses, F is an effective F number on the first conjugate point side, L 0 ′ is an air equivalent distance along the reference axis from the first conjugate point to the first mirror, L 1 is an air equivalent distance along the reference axis from the first mirror to the second mirror and η is an absolute value of an angle formed by the normal of the second mirror and the reference axis at an intersection of the reference axis and the second mirror. Furthermore, an image-forming optical system of the present invention for sequentially reflecting and projecting luminous fluxes which are modulated by a display element using a plurality of curved mirrors, comprises the following elements. That is, an image-forming optical system comprises a first to final (k)th mirrors provided as the above-described plurality of curved mirrors, in the order in which luminous flux progresses from the display element side. Then, the (k−1)th, (k−2)th and (k−3)th mirrors are given positive, negative and positive power, respectively and the (k)th mirror is given positive power. Furthermore, an image-forming optical system of the present invention for sequentially reflecting and projecting luminous fluxes which are modulated by a display element using a plurality of curved mirrors, comprises the following elements. That is, an image-forming optical system comprises a first to final (k)th mirrors are provided as the above-described plurality of curved mirrors in the order in which luminous flux progresses from the display element side. Then, when a reference axis is an optical path along which a central light ray of the luminous flux from the display element progresses and distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), respectively, the following condition should be satisfied. L ( k −1)> L ( k −2)  (4) A detailed configuration of the image-forming optical system, projection type image display apparatus and image pickup apparatus of the invention, the above and other objects and features of the invention will be apparent from the embodiments, described below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a detailed block diagram of a projection optical system of a projection type image display apparatus according to an embodiment of the present invention; FIG. 2 is an overall block diagram of the projection optical system of the projection type image display apparatus shown in FIG. 1 ; FIG. 3 is a block diagram of an image pickup apparatus according to another embodiment of the present invention; and FIG. 4 is a block diagram of a conventional projection optical system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. Before explaining embodiments of the present invention, the way of presenting the configuration specifications in the embodiments and elements common to all the embodiments will be explained. The embodiments of the present invention will explain the case where an image-forming optical system of the present invention is mainly used as the projection optical system. In this case, the first conjugate point which is nearer corresponds to a point on an image display element and the second conjugate point which is farther corresponds to a point on a screen (a point on an image pickup medium such as an image pickup element corresponds to the first conjugate point and a point on an object corresponds to the second conjugate point in the case of an image pickup optical system). Then, each reflecting surface making up the optical system is determined in such a way that the (m)th surface in the order in which light progressing from the first conjugate point side (image display element side) to the surface of the image on the second conjugate point side (screen or projection surface side) arrives is expressed as the “(m)th surface”. In the case of the projection optical system, the image display element corresponds to the object and the projection surface (screen) corresponds to the surface of the image. Each reflecting surface is a surface mirror made up of a surface form molded with plastics, etc. coated with a reflection coating, etc. and the medium that fills the space between mirrors is air. Thus, all the embodiments are so-called hollow type optical systems. By the way, since it is possible to give an aspheric surface power component with a diffraction grating to the surface of a spherical surface mirror by shaping at least one of the reflecting surfaces like a diffraction grating, the shape of the base mirror can be simplified in comparison with an aspheric surface (shaped) reflector. Furthermore, by forming a plurality of free form surfaces on the back surface of a bulk of glass or plastic and forming a reflecting coating on them to use at least one reflecting surface as a backside mirror, it is also possible to provide a configuration whereby luminous flux progresses inside the bulk medium. In order to explain the embodiments, three items; a reference axis, a global coordinate system and a local coordinate system, will be defined first. Since the optical system according to the embodiments of the present invention is an off-axial optical system, the optical surfaces making up the optical system do not have a common optical axis. In the embodiments of the present invention, light emitted from the center of the image display element which is an object in the direction perpendicular to this image display element is a reference, and this light ray is regarded as a reference light ray. Then, the optical path along which this reference light ray progresses, that is, the optical path along which the central light ray of the luminous flux progresses from the first conjugate point is regarded as a reference axis. The reference axis has directivity (orientation). The direction of the reference axis is the one in which the reference light ray progresses to form an image. The reference axis finally reaches the center of the surface of the image while changing the direction along the set sequence of surfaces according to the law of reflection. Then, a global coordinate system (global coordinates are expressed by capital letters XYZ) with the center of the surface of the object which is the image display element as the origin will be considered. The axes of the global coordinate system will be defined as follows. Suppose the coordinate system is a right-hand system. {circle around (1)} Z-axis: A straight line which passes through the global origin and is perpendicular to the surface of the object. The direction from the surface of the object to the first mirror is considered positive. {circle around (2)} Y-axis: A straight line which passes through the global origin and forms 90° counterclockwise with respect to the Z-axis. This embodiment assumes that the above-described reference axis exists within the YZ plane. Therefore, all the curved mirrors making up the reflection image-forming optical system of each embodiment are tilted within the YZ plane. Furthermore, a meridional cross section coincides with the YZ plane. Furthermore, in the drawings of the respective embodiments, the plane of the sheet coincides with the YZ plane. The orientation of the sign of the Y-axis is arbitrary. However, in the embodiments, the direction in which the reference axis is reflected and progresses by each mirror is considered positive. Therefore, the positive direction of the Y-axis in the drawing of each embodiment is upward in the drawing. {circle around (3)} X-axis: A straight line which passes through the origin and is perpendicular to the Z-axis and Y-axis (straight line perpendicular to the plane of the sheet in each drawing). Since it is the right-hand system, the direction toward the back of the sheet is positive. When expressing the shape of the (m)th surface making up the optical system, setting a local coordinate system (local coordinate system is expressed with small letters xyz) corresponding to each surface by regarding each point advanced by the distance between surfaces on the reference axis as a local origin is easier to understand the shape of each of surfaces, than expressing the shapes of the surfaces in a global coordinate system, and therefore the shape of the (m)th surface is expressed in a local coordinate system (right-hand system). Furthermore, suppose tilting of a surface is also expressed by tilting the local coordinate system corresponding to each surface. The tilt angle within the YZ plane of the local coordinate system corresponding to the (m)th surface is expressed with an angle θm (unit is °, which will be omitted hereafter) with the counterclockwise direction with respect to the Z-axis of the global coordinate system considered positive. Thus, all the origins of the local coordinates of the respective surfaces in the embodiments are naturally on the YZ plane. In the embodiments, there is a relationship between ξ, and η and θm described below: 2×ξ=|2×θ 1 |, 2×η=|2×(θ 2 −2×θ 1 )| Furthermore, there is no eccentricity of planes within the XZ and XY planes. Additionally, the y-axis and z-axis of the local coordinates (x, y, z) of the (m)th surface are inclined by an angle θm within the YZ plane with respect to the global coordinate system (X, Y, Z) and are specifically set as follows: {circle around (4)} z-axis: A straight line which passes through the origin of the local coordinates and is inclined by an angle θm counterclockwise within the YZ plane with respect to the Z direction in the global coordinate system. {circle around (5)} y-axis: A straight line which passes through the origin of the local coordinates and forms 90° counterclockwise within the YZ plane with respect to the z direction. {circle around (6)} x-axis: A straight line which passes through the origin of the local coordinates and is perpendicular to the YZ plane. {circle around (7)} Lm is scalar indicating the distance between the origins of local coordinates of the (m)th and (m+1)th surfaces. L 6 is the distance from the 6th mirror to the surface of the image. Moreover, as described above, both the global coordinates and local coordinates use the YZ plane and yz plane as the meridional cross sections of their respective optical systems. The optical system of the embodiments have at least a rotationally asymmetrical aspheric surface and the shape is expressed in the local coordinate system by the following expression, where C 02 , C 20 , C 03 , C 21 , C 04 , C 22 , C 40 , C 05 , C 23 , C 41 , C 06 , C 24 , C 42 and C 60 are aspheric surface coefficients. z=C 02 y 2 +C 20 x 2 +C 03 y 3 +C 21 x 2 y+C 04 y 4 +C 22 x 2 y 2 +C 40 x 4 +C 05 y 5 +C 23 x 2 y 3 +C 41 x 4 y+C 06 y 6 +C 24 x 2 y 4 +C 42 x 4 y 2 +C 60 x 6   (5) Since the above-described curved surface expression (5) consists of only terms of even degrees with respect to x, the curved surface specified by the above-described curved surface expression is plane-symmetric with the yz plane as the symmetric plane. The above-described curved surface expression also expresses a shape symmetric with respect to the xz plane when the following condition is satisfied: C 03 =C 21 =C 05 =C 23 =C 41 =0 Furthermore, it expresses a rotationally symmetric shape when the following conditions are satisfied: C 02 =C 20 C 04 = C 40 = C 22 /2 C 06 = C 60 = C 24 /3 =C 42 /3 When the above-described conditions are not satisfied, it expresses a rotationally asymmetric shape (shape of free form surface). Then, embodiments of the present invention will be explained. FIG. 1 and FIG. 2 show the entire optical path from the reflection projection optical system (image-forming optical system) formed of free form reflection mirrors up to a screen 10 . FIG. 1 is a schematic view showing the configuration of a projection type image display apparatus using the projection optical system. FIG. 2 is an overall view of the projection optical system in FIG. 1 . With respect to numerical examples, only design values will be shown and drawings will be omitted, but they have almost the same configuration as this embodiment. This embodiment is a projection optical system that projects light whose intensity is modulated onto the screen 10 by the image display element 1 and uses an off-axial system to form an image on the screen. In FIG. 1 , the surface of the object coincides with the surface of the image display element 1 . The image display element 1 is illuminated by luminous flux emitted from an illumination system (not shown) and transmitting through the element 1 from the back. The illumination system is constructed of a lamp, condenser lens and filter for selecting a wavelength, etc. Furthermore, this embodiment has a configuration whereby three RGB image display elements are used to combine RGB three color image light components through a color combining prism 2 and project the combined light. However, FIG. 1 only shows one image display element 1 . This embodiment is constructed of six reflecting surfaces of a first mirror (concave surface) 3 , second mirror (convex surface) 4 , third mirror (concave surface) 5 , fourth mirror (convex surface) 6 , fifth mirror (concave surface) 7 and sixth mirror (concave surface) 8 . An aperture-stop S is placed between the second mirror 4 and third mirror 5 . The luminous flux from the image display element 1 is reflected by the first mirror to transform into substantially parallel luminous flux and then reflected by the second mirror 4 while being kept substantially parallel. All the above-described reflecting surfaces are only symmetric with respect to the YZ plane and rotationally asymmetric. The luminous flux emitted from the image display element 1 forms an intermediate image on an intermediate image forming surface between the fifth mirror 7 and sixth mirror 8 and the image of the aperture-stop S is formed at a position behind the sixth mirror 8 (on the screen 10 side). In the following numerical embodiments, the size of the image display element 1 is diagonal 0.7 inches (10.7×14.2 mm). Furthermore, the size of the screen 10 is diagonal 70 inches of an aspect ratio 3:4 (1067×1422 mm). The normal of the screen 10 is inclined 40 degrees with respect to the reference axis immediately before incidence upon the screen 10 . By the way, the projection optical system of the present invention may also be constructed to have lens systems and other reflection optical systems in addition to the optical system shown in FIG. 1 and FIG. 2 . The features of the projection optical system (image-forming optical system) of this embodiment will be explained below. Here, it is the prerequisite that the first mirror 3 is provided with power to transform the luminous flux spread from the image display element 1 to substantially parallel luminous flux and the second mirror 4 is provided with moderate power to reflect this substantially parallel luminous flux as is. First, the projection optical system according to this embodiment satisfies the following condition: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]  (1) where ξ is an absolute value of an angle formed by the normal of the first mirror 3 (that is, the local z-axis in the first mirror 3 ) and the reference axis at an intersection of the reference axis and the surface of the first mirror 3 , η is an absolute value of an angle formed by the normal of the second mirror 4 (that is, the local z-axis in the second mirror 4 ) and the reference axis at an intersection of the reference axis and the surface of the second mirror 4 , and F is an effective F number on the first conjugate point (image display element 1 ) side. Expression (1) is a condition to enable luminous fluxes folded by reflections on the first mirror 3 and second mirror 4 to come as close as possible to each other. Within the meridional cross section, a marginal light ray on the optical path from the image display element 1 to the first mirror 3 and a marginal light ray on the optical path of the luminous flux reflected by the second mirror 4 are nearly parallel on the neighboring sides, and therefore when, for example, the first mirror 3 and third mirror 5 are placed side by side, it is possible to shorten the distance between the spatial positions of these first and third mirrors, and as a result, it is possible to make a configuration of these neighboring mirrors more compact. When F is the effective F number on the image display element 1 side of the optical system, the angle formed by the marginal light ray on the optical path from the image display element 1 to the first mirror 3 with respect to the reference axis on the same optical path is given as: Arctan(1/2F)  (1-a) The luminous flux from the first mirror 3 at the height of each object is converged into substantially parallel luminous flux and reaches the second mirror 4 . Then the luminous flux reflected by the second mirror 4 forms the following angle with respect to the reference axis: 2×(ξ−η)  (1-b) The luminous flux reflected by the second mirror 4 is substantially parallel luminous flux, and therefore the marginal light ray also has a similar angle. At this time, if the marginal light rays on the neighboring sides are nearly parallel to each other, that is, the difference in absolute values of the angles shown in expressions (1-a) and (1-b) is set to 10° or less including certain margins, it is possible to bring the optical path from the image display element 1 to the first mirror 3 sufficiently close to the optical path of the luminous flux reflected by the second mirror 4 without interfering with each other. Thus, from expressions (1-a) and (1-b), the above-described expression (1) is obtained as the conditional expression concerning the absolute value of the angle. Then, when P is the size of the display surface of the image display element 1 within the meridional cross section, F is an effective F number on the image display element 1 side of the optical system, L 0 ′ is an air equivalent distance along the reference axis from the image display element 1 to the first mirror 3 , and L 1 is an air equivalent distance along the reference axis from the first mirror 3 to the second mirror 4 , the following condition should be satisfied: 2.3≧2 ×L 1 ×sin η/Φ 1 ≧1.1  (2) where, Φ 1 =L 0 ′/ F+P   (3) Expression (2) indicates the condition for preventing each mirror from becoming too large and setting each mirror to a size within the necessary minimum range so that luminous fluxes do not interfere with each other. Φ 1 indicated by Expression (3) is an approximation of the effective diameter of luminous flux in the meridional section of the image display element 1 on the first mirror 3 . By the way, when a prism (e.g., color combining prism), etc. is placed on the optical path between the image display element 1 and the first mirror 3 , the above-described air equivalent distance L 0 ′ can be calculated as: L 0 ′= D 0 + D 1 / N+L 0   (2-a) where D 1 is a thickness of the prism measured along the reference axis, N is a refraction index of the glass of the prism, D 0 is a distance measured along the reference axis from the image display element 1 to the prism incident end and L 0 is a distance measured along the reference optical axis from the prism exiting end to the first mirror 3 . Furthermore, 2×L 1 ×sin η  (2-b) indicates an approximate distance of the light ray (reference light ray) on the reference axis, which progresses after being reflected at the center of the first mirror 3 and reflected by the second mirror 4 , from the center of the first mirror 3 when this light ray passes right next to the first mirror 3 . In the case where the above-described third mirror 5 is provided as described in this embodiment, the third mirror 5 is often necessarily placed next to the first mirror 3 on the substantially same plane in order to design a compact optical system. In this case, the value in above-described expression (2-b) is a value that can be said to be the distance between the center of the first mirror 3 and the center of the third mirror 5 . If the distance according to above-described expression (2-b) is too long, the first mirror 3 is distant from the third mirror 5 , which increases the size of the optical system. If the distance is too short, the luminous flux on the first mirror 3 overlaps with the luminous flux of the third mirror 5 , failing to establish the optical system. Since luminous flux is transformed to substantially parallel luminous flux by the first mirror 3 and the second mirror 4 has only weak power that preserves the condition, the diameter of luminous flux on the first mirror 3 is almost equivalent to the diameter of luminous flux on the third mirror 5 . Therefore, the following expression (2-c) expresses the magnitude of the value in expression (2-b) corresponding to the value in expression (3), that is, the distance from the center the first mirror 3 to the center of the third mirror 5 (reference axis of the reflection optical path from the second mirror 4 ) corresponding to the effective diameter of luminous flux on the first mirror 3 . If: 2×L 1 ×sin η/Φ 1   (2-c) is within the range of 1.1 times to a maximum of 2.3 times (that is, if above-described expression (2) is satisfied) including various margins, it is possible to provide an optical system of an appropriate size which is not too large or which prevents luminous fluxes from interfering with each other. Furthermore, in this embodiment, when the first to final (k)th mirrors are provided, in the order in which luminous flux progresses from the image display element 1 side, the (k−1)th, (k−2)th and (k−3)th mirrors are given positive, negative and positive power, respectively and the (k)th mirror is given positive power. Thus, arranging the three mirrors immediately before the final mirror as positive, negative and positive, that is, concave, convex and concave mirrors provides a power configuration similar to the Offner type, which is known to be non-aberration optical system with a reflection type equimultiple exposure apparatus, etc. This makes it unlikely to cause unnecessary adverse influences on luminous fluxes whose aberration has been corrected by mirrors immediately before the three mirrors. Further, making the surfaces of these three mirrors rotationally asymmetric (free form surfaces) allows the residual aberration components that have not been successfully removed from the surfaces before the above-described three mirrors to be effectively corrected. Then, as it is known that using a positive or concave mirror as the final mirror is advantageous in correcting aberration for projection at a high angle of elevation, it is possible to form an image of the aperture-stop after the final mirror (projection surface side). Furthermore, when the distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), respectively, the following condition should be satisfied. L ( k −1)> L ( k −2)  (4) In the case of projection at a high angle of elevation, forming an image of the aperture-stop after the final mirror is known to be advantageous in correcting aberration of the optical system. And this expression (4) is expressed also as an effective condition to prevent spatial interference between the luminous flux reflected by the final mirror and directed to the projection surface, and the edge of the preceding mirror. Furthermore, in the case where a concave mirror is used for the final mirror, spatially separating the light rays forming respective portions of an angle of view on this concave surface as much as possible, when the light rays are reflected on the concave surface, is advantageous in correcting aberration. This has an effect of making it easier to correct aberration remaining for each portions of the angle of view through control of local surface shapes on the final mirror and correct distortion of the diagonally projected image by controlling the curvature of the field. As the configuration condition for this, when the system is constructed of a total of k surfaces and the distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), the above-described expression (4) should be satisfied. Satisfying this condition makes it possible to place only the final mirror at a place more distant from the immediately preceding mirror with regard to distances among the mirrors. This produces an extra space for the space around the final mirror, avoiding interference in configuration such as eclipse of luminous flux or making it easier to adopt a configuration for reflecting luminous flux while keeping a tendency of separating luminous flux at each portion of the angle of view on the surface of the final mirror. By satisfying the above-described conditions, it is possible to realize an image-forming optical system suitable as the image-forming optical system for a projection type image display apparatus especially using a transmission type image display element, only made up of reflecting surfaces combining a plurality of curved mirrors, whose object side is substantially telecentric, bright (e.g., brighter than F3.0), avoiding size expansion of the mirrors and capable of projection at a high angle of elevation. Numerical embodiments of the present invention will be shown below. In all the numerical embodiments: {circle around (1)} The total number of reflection curved surfaces is 6. {circle around (2)} The distance D 0 from the surface of an object (image display element 1 ) to the color combining prism 2 is 11.0 mm. {circle around (3)} The thickness D 1 of the color combining prism 2 is 28.0 mm. {circle around (4)} The refraction index Nd of the color combining prism 2 is 1.872690 and Abbe's number νd is 32.33. {circle around (5)} The distance L 0 from the exiting end surface of the prism 2 to the local coordinate origin of the first mirror 3 is 40.0 mm. (Numerical Embodiment 1) Table 1 shows design values according to numerical embodiment 1. Configuration data is numbered sequentially from the surface of the image display element 1 to the surface of the image (surface of the screen 10 ). The F number on the object side is 2.0. TABLE 1 1st Mirror L 1 60 θ 1 −27 C2 −2.62990E−03 C3 −2.16320E−07 C4 −1.20530E−07 C5 −1.49020E−09 C6 −1.36120E−11 C20 −1.59860E−03 C21 −1.06840E−05 C22 −1.47820E−07 C23 −6.39140E−11 C24 2.09980E−11 C40 −1.12010E−07 C41 −1.06060E−09 C42 −2.51680E−11 C60 −2.01920E−11 2nd Mirror L 2 58 θ 2 −17 C2 2.57220E−04 C3 −1.26550E−05 C4 −1.68350E−07 C5 −1.37600E−09 C6 −2.05140E−11 C20 6.90530E−04 C21 −1.29610E−05 C22 −1.45430E−07 C23 −2.12890E−09 C24 −2.81640E−11 C40 −1.00680E−07 C41 −1.71720E−09 C42 −3.23350E−11 C60 −4.62060E−12 3rd Mirror L 3 60 θ 3 −6 C2 −2.88920E−03 C3 −1.27960E−05 C4 8.15880E−08 C5 −1.26220E−09 C6 8.58590E−13 C20 −3.93300E−03 C21 −4.86140E−06 C22 4.39810E−08 C23 −3.36290E−09 C24 1.91890E−11 C40 −3.49090E−08 C41 −1.04590E−09 C42 9.92250E−12 C60 −5.89450E−13 4th Mirror L 4 60 θ 4 +7 C2 −4.66820E−03 C3 −2.20370E−06 C4 4.58740E−07 C5 −4.70960E−09 C6 −8.87360E−11 C20 −7.09870E−04 C21 1.03720E−04 C22 −4.49650E−07 C23 −3.48160E−08 C24 1.81040E−10 C40 −4.09900E−08 C41 −1.14720E−08 C42 4.39340E−10 C60 −1.37690E−10 5th Mirror L 5 90 θ 5 +18 C2 −2.87050E−03 C3 −4.52490E−07 C4 −2.48480E−08 C5 −8.63240E−10 C6 1.23230E−11 C20 −1.14370E−02 C21 5.48810E−05 C22 −6.98790E−07 C23 4.50210E−09 C24 −7.34250E−11 C40 −9.51650E−07 C41 1.28360E−08 C42 −2.39830E−10 C60 2.20530E−11 6th Mirror L 6 2360 θ 6 +15 C2 3.11270E−03 C3 −2.39510E−05 C4 3.15000E−07 C5 −3.11740E−09 C6 1.50310E−11 C20 −1.10200E−03 C21 −1.48510E−05 C22 −3.39740E−07 C23 5.01470E−09 C24 −7.54510E−11 C40 −9.93860E−08 C41 9.25250E−10 C42 4.09830E−11 C60 2.63620E−11 (Numerical Embodiment 2) Table 2 shows design values according to numerical embodiment 2. The F number on the object side is 2.2. TABLE 2 1st Mirror L 1 60 θ 1 −27 C2 −3.45470E−03 C3 −3.43110E−06 C4 −1.18920E−07 C5 −1.10840E−09 C6 −1.75660E−11 C20 −3.86300E−03 C21 −2.80060E−05 C22 −4.51860E−07 C23 −2.65260E−09 C24 −1.78960E−11 C40 1.13220E−07 C41 −1.85280E−09 C42 −6.53940E−11 C60 5.04350E−11 2nd Mirror L 2 58 θ 2 −17 C2 −8.95970E−05 C3 −1.16880E−05 C4 −2.46060E−07 C5 −2.31260E−09 C6 −5.05480E−11 C20 −7.08200E−03 C21 −7.05900E−05 C22 −7.00660E−07 C23 −7.54210E−09 C24 −1.17420E−10 C40 2.30970E−07 C41 −1.04850E−09 C42 −7.24290E−11 C60 1.76270E−10 3rd Mirror L 3 60 θ 3 −6 C2 −2.97790E−03 C3 −1.31910E−05 C4 4.97300E−08 C5 −9.14870E−10 C6 −4.76540E−12 C20 −5.95630E−03 C21 1.40430E−07 C22 −1.76920E−07 C23 −1.80170E−09 C24 2.84940E−12 C40 −1.97720E−07 C41 9.89490E−11 C42 −1.36170E−11 C60 −1.31600E−11 4th Mirror L 4 60 θ 4 7 C2 −3.22570E−03 C3 −5.14890E−06 C4 3.03330E−07 C5 −2.94870E−09 C6 4.21640E−11 C20 −2.32130E−03 C21 1.62720E−04 C22 −1.37010E−06 C23 9.54750E−09 C24 −1.38730E−10 C40 −3.60700E−07 C41 −3.32270E−08 C42 5.26710E−10 C60 3.74070E−10 5th Mirror L 5 90 θ 5 18 C2 −3.23350E−03 C3 4.40360E−06 C4 1.50230E−08 C5 5.95530E−10 C6 5.44740E−12 C20 −1.13810E−02 C21 −1.24900E−05 C22 3.15290E−07 C23 3.29840E−10 C24 7.28890E−12 C40 −9.66530E−07 C41 −5.75770E−09 C42 2.69510E−10 C60 −2.18500E−10 6th Mirror L 6 2360 θ 6 15 C2 1.34650E−03 C3 −1.68040E−06 C4 9.91660E−08 C5 −1.55470E−09 C6 1.11750E−11 C20 −1.14430E−04 C21 −7.55550E−06 C22 1.11850E−07 C23 7.43030E−10 C24 −3.55670E−11 C40 1.54350E−07 C41 5.83010E−09 C42 2.29590E−11 C60 −5.96550E−12 (Numerical Embodiment 3) Table 3 shows design values according to numerical embodiment 3. The F number on the object side is 2.5. TABLE 3 1st Mirror L 1 60 θ 1 −27 C2 −2.82290E−03 C3 −8.39020E−06 C4 −2.15920E−07 C5 −1.73820E−09 C6 −1.18040E−11 C20 −2.92540E−03 C21 −2.56290E−05 C22 1.77300E−08 C23 2.67590E−09 C24 1.17010E−11 C40 5.95940E−08 C41 −2.55510E−09 C42 −4.38720E−11 C60 1.72090E−11 2nd Mirror L 2 58 θ 2 −17 C2 6.15930E−05 C3 −2.04790E−05 C4 −2.61300E−07 C5 −3.05570E−09 C6 −4.74500E−11 C20 −2.76560E−03 C21 −1.07810E−05 C22 4.56360E−07 C23 7.40050E−09 C24 9.86610E−11 C40 5.81510E−08 C41 7.63600E−10 C42 2.34840E−11 C60 2.62710E−11 3rd Mirror L 3 60 θ 3 −6 C2 −2.47730E−03 C3 −1.69230E−05 C4 1.07440E−07 C5 −1.48060E−09 C6 −3.79440E−12 C20 −5.26230E−03 C21 7.37020E−06 C22 1.07850E−07 C23 −2.48380E−09 C24 4.52080E−11 C40 −1.42710E−07 C41 4.94900E−10 C42 4.14600E−11 C60 −7.30370E−12 4th Mirror L 4 60 θ 4 7 C2 −2.03880E−03 C3 −2.71950E−08 C4 1.18910E−07 C5 −1.99550E−09 C6 −3.81030E−11 C20 −1.44660E−03 C21 1.87520E−04 C22 −8.91840E−07 C23 −3.74300E−09 C24 9.17790E−11 C40 −2.20620E−06 C41 −4.66870E−08 C42 9.73520E−10 C60 1.76210E−09 5th Mirror L 5 90 θ 5 18 C2 −1.68920E−03 C3 2.01510E−06 C4 −1.62160E−07 C5 −1.10580E−09 C6 1.88300E−11 C20 −1.06760E−02 C21 2.38450E−05 C22 −8.61220E−08 C23 −4.13700E−09 C24 −5.56080E−11 C40 −7.14770E−07 C41 3.19510E−09 C42 −8.22270E−11 C60 −8.16020E−11 6th Mirror L 6 2360 θ 6 15 C2 3.65330E−03 C3 −2.17560E−05 C4 2.66200E−07 C5 −2.74490E−09 C6 1.44350E−11 C20 −2.71280E−03 C21 −3.02460E−06 C22 −4.83180E−07 C23 5.47270E−09 C24 −7.46490E−11 C40 6.47570E−07 C41 4.93880E−09 C42 2.53670E−10 C60 −1.76960E−10 (Numerical Embodiment 4) Table 4 shows design values according to numerical embodiment 4. The F number on the object side is 2.8. TABLE 4 1st Mirror L 1 60 θ 1 −27 C2 -2.8898E−03 C3 -7.8773E−06 C4 -2.0967E−07 C5 -1.7026E−09 C6 -1.3058E−11 C20 -2.8814E−03 C21 -2.4490E−05 C22 5.8433E−08 C23 3.4577E−09 C24 1.6376E−11 C40 9.1834E−08 C41 -2.6967E−09 C42 -3.4943E−11 C60 3.2961E−11 2nd Mirror L 2 58 θ 2 −17 C2 5.0246E−05 C3 -1.9943E−05 C4 -2.5939E−07 C5 -2.8618E−09 C6 -4.8075E−11 C20 -2.8115E−03 C21 -5.9288E−06 C22 5.7097E−07 C23 8.8495E−09 C24 1.1055E−10 C40 7.4373E−08 C41 1.1162E−09 C42 2.6441E−11 C60 3.1819E−11 3rd Mirror L 3 60 θ 3 −6 C2 -2.4331E−03 C3 -1.7384E−05 C4 1.1195E−07 C5 -1.4727E−09 C6 -5.4818E−12 C20 -5.3683E−03 C21 8.8846E−06 C22 1.3012E−07 C23 -2.2319E−09 C24 4.8964E−11 C40 -1.5317E−07 C41 7.2041E−10 C42 4.6359E−11 C60 -8.3890E−12 4th Mirror L 4 60 θ 4 7 C2 -1.9285E−03 C3 -9.3206E−07 C4 1.3423E−07 C5 -2.0951E−09 C6 -4.4435E−11 C20 -2.3054E−03 C21 2.1589E−04 C22 -1.0703E−06 C23 -2.8856E−09 C24 8.3340E−11 C40 -2.5050E−06 C41 -5.6641E−08 C42 1.2383E−09 C60 2.2638E−09 5th Mirror L 5 90 θ 5 18 C2 -1.5474E−03 C3 2.5468E−06 C4 -1.8768E−07 C5 -1.5289E−09 C6 2.3362E−11 C20 -1.0472E−02 C21 1.9738E−05 C22 1.6806E−08 C23 -4.6789E−09 C24 -6.4027E−11 C40 -7.1077E−07 C41 2.4256E−09 C42 -4.9469E−11 C60 -1.1212E−10 6th Mirror L 6 2360 θ 6 15 C2 3.5875E−03 C3 -2.0414E−05 C4 2.4500E−07 C5 -2.4251E−09 C6 1.1429E−11 C20 -2.7382E−03 C21 -1.9202E−06 C22 -4.9902E−07 C23 5.3182E−09 C24 -7.0459E−11 C40 6.8669E−07 C41 4.8212E−09 C42 2.8058E−10 C60 -2.0137E−10 Here, the calculation results of the above-described expressions (1) and (4) in the above-described numerical embodiments are shown. TABLE 5 Expression (1) a b ≦10° F ξ η Arctan (1/2F) | 2(ξ − η) | |a − b| Judgement Embodiment 1 2.0 27 37 14.036 20 5.9638 available Embodiment 2 2.2 27 37 12.804 20 7.1957 available Embodiment 3 2.5 27 37 11.310 20 8.6901 available Embodiment 4 2.8 27 37 10.125 20 9.8753 available TABLE 6 Expression (4) 2.3 ≦ Expression ≦ 1.1 DO D1 N LO F P φ1 L1 η 2L1sinη 2L1sinη/φ1 Judgement Embodiment 1 11 28 1.87269 40 2.0 5.4 38.376 60 37 72.2178 1.882 available Embodiment 2 11 28 1.87269 40 2.2 6.4 36.378 60 37 72.2178 1.985 available Embodiment 3 11 28 1.87269 40 2.5 7.4 33.781 60 37 72.2178 2.138 available Embodiment 4 11 28 1.87269 40 2.8 8.4 31.954 60 37 72.2178 2.260 available The above embodiments have described the projection type image display apparatuses, but the present invention is also applicable to an image pickup optical system. When an image-forming optical system of the present invention is used as an image pickup optical system, as shown in FIG. 3 , the positions of the object and image of the above-described optical system can be switched round. Then, the image display element may be replaced by an image pickup element 20 such as a CCD or CMOS sensor, and the image of the object 40 is formed on the image pickup element 20 through 30 by the image-forming optical system according to the invention. In the case where a color CCD is used as the image pick element 20 , color images can be taken by a single CCD, and therefore no prism is required. Further, changing the specification as appropriate according to the operating conditions such as shortening the focal length compared to the projection type image display apparatus makes it possible to realize an apparatus to read a document placed on a flat surface from diagonal direction as in the case of an art camera. In addition, the present invention can also be used as a general image pickup apparatus such as a monitoring camera. When the image-forming optical system is used for an image pickup system, the image pickup system has the merit of producing no color aberration as far as the system is a surface reflection system as in the case of a projection system. For example, the prism for combining RGB three-color liquid crystal images for the projection type image display apparatus can be changed to a cover glass (a thin plate of approximately 0.7 mm in thickness) of the CCD. To be precise, since the above-described prism and cover glass are refraction elements, color aberration may be generated there, but the operating conditions are limited in a projection system, and therefore it is possible to remove influences of color aberration through an adjustment and make the most of the feature of being free of color aberration of the reflection image-forming optical system. On the other hand, in the case of the image pickup system, conditions such as image pickup distance may vary, etc., but the cover glass is thin, and therefore little color aberration is generated here and there are possibly no substantial influences. As described above, according to the present invention, it is possible to bring luminous fluxes folded by reflections on the first mirror and second mirror of the image-forming optical system close to each other without interference with each other and thereby reduce the size of the image-forming optical system made up of only reflecting surfaces. Furthermore, the present invention can prevent the mirrors from becoming too big and reduce them to within a minimum necessary range preventing luminous fluxes from interfering with each other and thereby reduce the size of the image-forming optical system. Moreover, the three positive, negative and positive mirrors before the final mirror can optimally correct various aberrations and use of a positive mirror for the final mirror can form an image of the aperture-stop after the final mirror (projection surface side), which is advantageous in correcting aberration for projection at a high angle of elevation. Furthermore, when an image of the aperture-stop is formed after the final mirror, the image-forming optical system can prevent spatial interference between the luminous flux directed to the projection surface and the edge of the mirror immediately before the final mirror. For the above-described reasons is it possible to realize an image-forming optical system which is especially suitable for the projection type image display apparatus using a transmission type image display element. Further, it is possible to realize an image-forming optical system which is made up of only reflecting surfaces by a combination of a plurality of curved mirrors and whose object side is substantially telecentric, bright, preventing expansion in the size of mirrors, capable of projection at a high angle of elevation. While preferred embodiments have been described, it is to be understood that modification and variation of the present invention may be made without departing from the sprit or scope of the following claims.

The present invention discloses an image-forming optical system provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, sequentially starting with a first conjugate point which is nearer when an optical path is traced from the first conjugate point to a second conjugate point which is farther, comprises, a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux, and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Further, the optical system satisfies the following condition: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]

This application is a continuation of application Ser. No. 07/591,891, filed on Oct. 2, 1990, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fiber-reinforced molding compositions having superior mechanical properties which are based on polyphenylene ether resins, and also to a process for the preparation of these molding compositions. 2. Description of The Background Polyphenylene ethers (PPE), also known as polyphenylene oxides, are polymers having a high heat resistance and also good mechanical and electrical properties. As a rule, they are used as blends with polystyrene resins, for example, DE-C-2,119,301 and 2,211,005 and/or polyoctenylene (DE-A-3,442,273 and 3,518,277). Many attempts have been made to increase the rigidity of PPE-containing molding compositions by admixing reinforcing fibers composed of inorganic or organic material in the resin. For instance, DE-A-2,364,901 discloses polymer mixtures of PPE, polystyrene resins and glass fibers, the glass fibers used in this case having a length of between 3.1 and 25.4 mm, preferably of below 6.35 mm. EP-A-0,243,991 and the corresponding U.S. Pat. No. 4,749,737 describe the mixing of very short, unsized fibers with Si-H bond-containing siloxanes, to improve the fiber-matrix adhesion in the composition, followed by mixing in the melt with PPE and a polystyrene resin. A specific modification of the fiber surface by treating the glass fibers with vinylsilanes or gamma-glycidoxypropyl-trimethoxysilanes for use in PPE-containing molding compositions is described in DE-A-2,132,595, JP 73/97,954, JP 74/10,826 and JP 85/88,072. DE-A-2,719,305 proposes the opposite method, i.e. end-group modification of the PPE via a silylation carried out before compounding. This technique however is a roundabout and labor-intensive method of achieving an improved fiber-matrix coupling. A commonly used surface modification of the reinforcing fibers is achieved by treatment with aminoalkylsilanes, for example gamma-aminopropyltriethoxysilane. Glass fibers which have been sized in this manner are incorporated in numerous PPE-containing compositions, it always being necessary to additionally modify the composition of the thermoplastic matrix to bond the fibers to the matrix. For instance, JP 87/15,247 describes the addition of, for example, maleic anhydride-modified polypropylene. JP 85/46,951 describes the addition of ethylene-maleic anhydride copolymers and JP 85/44,535, DE-A-3,246,433 and JP 82/168,938 describe the addition of styrene-maleic anhydride copolymers. However, these polymeric additives have the disadvantage that they reduce the heat resistance of the molding compositions or else they are only partly compatible with the PPE matrix or in most cases are incompatible and therefore impair the mechanical properties of the molding compositions. A need continues to exist for a PPE based molding composition of improved mechanical properties. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide fiber-reinforced molding compositions based on PPE, which, while avoiding the disadvantages described above, exhibit an improved adhesion between fiber and matrix. Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a molding composition comprising a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of 30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene and 0.1 to 2.5 parts by weight of an α-β-unsaturated carboxylic acid derivative or a precursor thereof; b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces bear functional groups which are capable of entering into chemical coupling reactions with α,β-unsaturated carboxylic acid derivatives; and optionally c) dyes, pigments, plasticizers, flame retardant additives, processing auxiliaries, other customary additives or combinations thereof. DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: FIG. 1 is a scanning electron micrograph of the fiber reinforced molding composition of Comparative Example A; and FIGS. 2a and 2b are scanning electron micrographs of the fiber reinforced molding composition of Example 2 of the present invention, wherein FIG. 2b is an enlargement of FIG. 2a. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The molding compositions of the invention can be processed to give molded articles by the customary methods of thermoplastics processing, for example injection molding or press molding. Suitable polyphenylene ethers include primarily polyethers based on 2,6-dimethylphenol, the ether oxygen of one unit being bonded to the benzene nucleus of the adjacent unit. In principle, it is also possible to use other o,o'-dialkylphenols whose alkyl radical preferably contains a maximum of 6 carbon atoms as long as this radical does not have a tertiary carbon atom in the alpha position. Furthermore, it is possible to use phenols which are substituted only in one ortho-position by a tertiary alkyl radical, in particular a tertiary butyl radical. Each of the monomeric phenols listed may be substituted by a methyl group in the 3-position, and optionally also in the 5-position. Obviously, it is also possible to use mixtures of the monomeric phenols mentioned here. The polyphenylene ethers may be prepared, for example, in the presence of complex-forming agents such as copper bromide and morpholine, from the phenols as disclosed in DE-A-3,224,692 and 3,224,691. The viscosity numbers J, determined in accordance with DIN 53 728 in chloroform at 25° C. are in the range of from 35 to 80 cm 3 /g (concentration 5 g/l). Preference is given to the polymer of 2,6-dimethylphenol, poly-(2,6-dimethyl-1,4-phenylene ether), having a viscosity number J from 45 to 70 cm 3 /g. Normally, the polyphenylene ethers are used in the form of powders or granules. The polyoctenylenes are prepared by the ring-opening or ring-expanding polymerization of cyclooctene (see, for example, A. Draxler, Kautschuk+Gummi, Kunststoffe 1981, pages 185 to 190). Polyoctenylenes having different proportions of cis- and trans-double bonds and also different J-values and correspondingly different molecular weights are obtainable by methods known in the literature. Preference is given to polyoctenylenes having a viscosity number of from 50 to 350 cm 3 /g, preferably 80 to 160 cm 3 /g, determined on a 0.1% strength solution in toluene. 55 to 95%, preferably 75 to 85%, of their double bonds are in the trans-configuration. There are various methods of preparing a mixture of polyphenylene ether and the polyoctenylene. One method is to dissolve the two polymers in a suitable solvent and to isolate the mixture by evaporating off the solvent or by precipitating it with a non-solvent. Another method is to combine the two polymers in the melt. Further details are given in DE-A-3,518,277. In a preferred embodiment, the molding composition contains 1 to 10 parts by weight of polyoctenylene. α,β-Unsaturated carboxylic acid derivatives are understood to mean, for example, compounds of the formulae (I) and (II): R.sup.1 --CO--CR.sup.2 ═CR.sup.3 --CO--R.sup.4 (I) R.sup.1 --CO--CR.sup.2 ═CR.sup.3.sub.2 (II) in which R 1 and R 4 are hydroxyl, aryloxy and/or alkoxy groups having up to 12 carbon atoms or together are --O-- or --NR 5 --, R 2 and R 3 denote hydrogen, an alkyl or cycloalkyl group having up to 12 carbon atoms, an alkyl group substituted by the radical COR 1 , an aryl group, chlorine or together an alkylene group having up to 12 carbon atoms, while R 5 is hydrogen, alkyl, aralkyl or aryl groups, each having up to 12 carbon atoms. Examples of these acids are maleic acid, fumaric acid, itaconic acid, aconitic acid, tetrahydrophthalic acid, methylmaleic acid, maleic anhydride, N-phenylmaleimide, diethyl fumarate and butyl acrylate. In this selection, preference is given to the use of fumaric acid and maleic anhydride. Obviously, it is also possible to use mixtures. It is also possible to use precursors of α,β-unsaturated carboxylic acid derivatives of this type which, under the conditions of mixing in the melt, are converted to the said carboxylic acid derivatives by known reactions such as, for example, elimination or reverse Diels-Alder reaction. Obviously, it is possible to add other compounds which promote the incorporation of the α,β-unsaturated carboxylic acid derivatives, for example, by alternating copolymerization while grafting. Suitable compounds in this category are primarily vinylaromatics such as, for example, styrene, which enter into a reaction of this type in particular with maleic anhydride. The preparation of graft copolymers of this type is described in the German patent application DE-A-3,831,348. The styrene polymer which is optionally added during the preparation or the working-up of the polyphenylene ether should preferably be compatible with the polyphenylene ether used. Its molecular weight Mw is in the range from 1,500 to 2,000,000, preferably in the range from 70,000 to 1,000,000. Particularly preferred styrene polymers are polystyrene, impact-modified polystyrene and also styrene-butadiene copolymers. Obviously, mixtures of these polymers may also be used. The styrene-butadiene copolymers may be random, tapered or block copolymers. The toughness is increased by giving preference to the use of block copolymers of the A-B-A type. The polystyrene blocks A have an average molecular weight Mw of 4,000 to 150,000 and together make up to 33% by weight of the block copolymer. The polybutadiene block B, which may also be hydrogenated or partly hydrogenated, has an average molecular weight Mw of 20,000 to 480,000. The reinforcing fiber present in the molding composition of the invention bears on its surface preferably free amino, epoxide or isocyanate groups. Amino groups are introduced, for example, by sizing with a copolyamide, with low molecular weight amine compounds or specifically in the use of glass fibers, with gamma-aminopropyltriethoxysilane; epoxide groups by impregnation with uncrosslinked epoxy resins or, in the case of glass fibers, with gamma-glycidoxypropyltrimethoxysilane; isocyanate groups by sizing with a solution of uncrosslinked, preferably low molecular weight polyurethane resins. The components III are preferably used to a maximum amount of 30% by weight, relative to I. The individual components may be mixed either simultaneously or in succession. Generally, the unreinforced molding composition is initially prepared in granule or melt form and to this is admixed the functionalized fibers in a mixer having a good kneading action. This mixing may for example be carried out using a single or twin-screw kneader or co-kneader. Generally, the mixing temperature is between 250° and 350° C., preferably between 260° and 310° C., and the residence time is generally between 1 and 10 minutes, preferably between 3 and 5 minutes. The molding compositions of the invention can be processed by customary injection molding procedures under the same conditions as the corresponding prior-art thermoplastic molding compositions. Even large molded objects can be produced simply using the said molding compositions. The molding compositions of the invention are used to produce moldings which are subject to particular service stress (intermittent and/or constant), a good fiber-matrix adhesion being of crucial importance in these moldings. The molded objects are employed, for example, in the construction of machines and apparatus for example for gear wheels or pump components, in sporting equipment, in the motor vehicle industry or in the electrical industry. Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. Comparative Example A 100 parts by weight of polyphenylene ether having a J-value of 68 cm 3 /g, which has been obtained by oxidative coupling of 2,6-dimethylphenol, termination of the reaction and subsequent combined reaction/extraction in accordance with DE-A-3,313,864 and 3,323,777 followed by evaporation of the solvent and extruding the melt via a degassing extruder, are remelted with 2 parts by weight of diphenylcresyl phosphate (DISFLAMOLL® DPK, Bayer) and one part of the antioxidant IRGANOX® 1010 and also 15.6 parts by weight of an NH 2 group-bearing carbon fiber (GRAFIL® XAS/PA 6, Courtaulds Advanced Materials), which are metered into the PPE melt in a twin-screw kneader at 280° C. Before the product is discharged, the volatile components are removed in a degassing zone. The product is granulated, dried and injection molded to give test pieces. The properties obtained from these are listed in Table 1. It can be seen clearly from the scanning electron micrograph (SEM) that no adhesion exists between fiber and matrix (low temperature fracture surface) (FIG. 1). EXAMPLES 1 to 3 The experiment described in Comparative Example A is repeated but with the addition of 0.5 to 1.5 parts by weight of maleic anhydride to the mixture of PPE, diphenylcresyl phosphate and IRGANOX® 1010 and subsequent metering of the carbon fiber into the melt. The constituents and properties of the composition prepared in this way are listed in Table 1. The scanning electron micrograph from Example 2 shows that an excellent adhesion exists between fiber and matrix (low temperature fracture surface) (FIGS. 2a and 2b). COMPARATIVE EXAMPLE B The experiment described in Comparative Example A is repeated but, instead of the carbon fiber used in that example, an epoxy resin-sized carbon fiber (TENAX® HTA-6-CN, Akzo (Enka AG) is used (Table 1). EXAMPLE 4 The experiment described in Comparative Example B is repeated but, as described in Examples 1 to 3, 1.5 parts of maleic anhydride are additionally used (Table 1). Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. TABLE 1______________________________________ Example A 1 2 3 B 4______________________________________PPE Parts by 100 100 100 100 100 100 weightDiphenylcresyl Parts by 2 2 2 2 2 2phosphate weightIRGANOX ® Parts by 1 1 1 1 1 11010 weightMaleic Parts by -- 0.5 1 1.5 -- 1.5anhydride weightGRAFIL ® Parts by 15.6 15.6 15.6 15.6 -- --XAS/PA 6 weightTENAX ® Parts by -- -- -- -- 15.6 15.6HTA-6-CN weightModulus of MPa 8600 8400 9100 9200 7000 9500elasticity intensionDIN 53 457Tensile strength MPa 98 117 132 122 92 136DIN 53 455Elongation at % 1.5 1.8 1.9 2.2 1.9 1.8breakDIN 53 455Impact strength kJ/m.sup.2 13 17 17 13 14 16DIN 53 453______________________________________

A fiber-reinforced molding composition, comprising: a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of 30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene and 0.1 to 2.5 parts by weight of an α,β-unsaturated carboxylic acid derivative or a precursor thereof; b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces bear functional groups which are capable of entering into chemical coupling reactions with the α,β-unsaturated carboxylic acid derivatives; and optionally c) dyes, pigments, plasticizers, flame retardant additives, processing auxiliaries, other customary additives or combinations thereof.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to electronic commerce. More specifically, it relates to a system for performing virtual customized vehicle design including component allocation and pricing; as well as financing, purchase, negotiation, and final acquisition using an internet capable computing device. [0003] 2. Description of the Prior Art [0004] With the development of electronic commerce in recent years, there has been a substantial increase in the availability and sophistication of commercial websites specializing in the sale and distribution of various products and services. These websites typically have software interfaces which allow consumers, or potential consumers, to browse products and services prior to selecting and finalizing a sale for a particular product, service, or combination of products. For certain products, specifically those which are customizable by the addition or subtraction of various components or subcomponents, it is desirable to provide an interface which allows the user to select the various components to be assembled, and/or added or subtracted to an underlying base product. The more sophisticated of such interfaces also allow the user to visualize a completed version of the product, while also providing information on the pricing of the product. [0005] Still other interfaces associated with commercial sites allow for performing various actions relating to the completion of a transaction for the sale of customized goods and services including various methods for payment. However, these interfaces have limited capability for allowing a user to perform all of the necessary steps for customizing a product such as a vehicle, as there are many issues which arise from the acquisition and integration of disparate components from a plurality of manufacturers and/or dealers, primarily issues involving the price, availability, and even compatibility of components selected for inclusion with the final product, as well as the price and availability of the completed product. A single interface which allows a user to resolve all of these issues is the primary object of the invention. [0006] The following known prior art has been directed to providing a summary of the various systems of the prior art. [0007] U.S. Pat. No. 7,353,192 issued to Ellis et al., discloses a system which allows for customizing a vehicle and viewing a virtual image of the vehicle prior to purchase. [0008] U.S. Pat. No. 7,542,925 issued to Tung discloses a system for customizing a plurality of domestic environments, complete with visualization of completed environments, which allows a user to select and have shipped a desired combination of furniture and interior decor items. [0009] None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. SUMMARY OF THE INVENTION [0010] Briefly, the invention comprises an electronic system for the customization, visualization, integration, purchase, and acquisition of a vehicle; the system implemented on a computer server or equivalent device, where the server is accessible over the interne via a suitable end-user operated computing device, the server generating a menu driven visual interface viewable on the computing device. The system allows for all aspects of a customized vehicle purchase to be performed by the user, substantially streamlining the selection and acquisition process. Once a vehicle is selected using the system interface, a three dimensional simulation is presented on the user device, along with an additional menu for selecting various components to be added to the vehicle. Selected components are displayed positioned at the appropriate position on or within the vehicle, the system automatically configuring the view most suitable for providing a realistic virtual image of the component in situ. In addition, the system will show the manufacturer's suggested retail price (MSRP) for the vehicle as currently configured, with the price updated in real time as components are added/deleted. The system can be configured for direct access by the user or for access through a dealer website, where, in the latter case, an adjusted price based on a particular dealer's pricing schedule will be displayed. Once all components are selected, the system will interface with the vehicle manufacturer's inventory database to search the inventory to ensure chosen component parts/options are in stock and if not, expected date of receipt, and reserve the chosen component parts/options and schedule the vehicle in the manufacturer's production schedule. If the system is accessed through a dealer website, the interface will then offer an opportunity to negotiate a final sales price with the dealer, offer financing and payment options either through the manufacture's or dealer's financing options, and at the end of the process provide an electronic and/or print out of a sales agreement. [0011] Accordingly, it is a principal object of the invention to provide a comprehensive system for performing virtual customized vehicle design including component allocation and pricing; as well as financing, purchase, negotiation, and final acquisition using an interne capable computing device. [0012] It is a major object of this invention to provide a comprehensive system for performing virtual customized vehicle design which can be used to design any motor vehicle including, but not limited to, automobiles, motorcycles, and RVs. [0013] It is another object to provide a comprehensive system for performing virtual customized vehicle design which can be implemented through a dealer website. [0014] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for the inclusion of both components available from the manufacturer of a particular vehicle and compatible components from other manufacturers. [0015] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows the user to access price and availability of selected components. [0016] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for display of a realistic three dimensional virtual image of a selected vehicle including real time depiction of the vehicle as various components are added/deleted. [0017] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for negotiating a final sales price for a customized vehicle. [0018] It is another object of the invention to provide a comprehensive system for performing virtual customized vehicle design where a manufacturer builds custom vehicles exclusively in accordance with the method of the invention to substantially reduce parts inventory. [0019] Finally, it is a general goal of the invention to provide improved elements and components thereof in a system for the purposes described which is fully effective in accomplishing its intended purposes. [0020] Thus it can be seen that the potential fields of use for this invention are myriad and the particular preferred embodiment described herein is in no way meant to limit the use of the invention to the particular field chosen for exposition of the details of the invention. [0021] A comprehensive listing of all the possible fields to which this invention may be applied is limited only by the imagination and is therefore not provided herein. Some of the more obvious applications are mentioned herein in the interest of providing a full and complete disclosure of the unique properties of this previously unknown general purpose article of manufacture. It is to be understood from the outset that the scope of this invention is not limited to these fields or to the specific examples of potential uses presented hereinafter. [0022] These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. [0023] The present invention meets or exceeds all the above objects and goals. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS [0024] Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: [0025] FIG. 1 is a perspective view of an image of a vehicle shown on a product display screen to be customized in accordance with the inventive system. [0026] FIG. 2 is a graphical representation of the overall system of the invention illustrating the interconnection of the various computing resources necessary to perform the several functions of the invention. [0027] FIG. 3 is a flowchart of the system of the invention. [0028] FIG. 4 is a representation of a webpage associated with the system of the invention. [0029] FIG. 5 is a representation of a webpage associated with the system of the invention. [0030] FIG. 6 is a representation of a webpage associated with the system of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0031] Referring now to FIGS. 1 and 2 , a representative vehicle displayed on a simulated webpage, generally designated by the numeral 10 , is shown, the vehicle 10 to be customized and, if desired, purchased using the system of the present invention. The vehicle 10 can be modified both cosmetically and mechanically to enhance either aesthetics or performance or both. A key aspect of the invention is that a vehicle may be customized by the addition or removal of external and internal components using the system of the invention, with the resulting change in appearance, if any, being viewable on a product display screen transmitted to a user operated computing device or terminal 12 . In accordance with the method of the invention, the customized vehicle 10 would be available directly from a vehicle manufacturer (Ford, GM), where the manufacturer includes the selected components prior to shipping to a dealer selected by the user as described below. It can be appreciated that the vehicle manufacturer is in the best position to determine the compatibility of customizing components, and is therefore best able to choose the components from a wide variety of available components which can be most effectively integrated with a given vehicle. [0032] With particular reference to FIG. 2 , the system 14 may be provided as software for use with a host data processing or computing facility 18 . Single user operated computing devices such as a PC 12 may be selectively connected by one or more electronic networks 19 to various remote computing resources 16 , including the host computing facility 18 of the present invention, either by wire or wirelessly via, e.g., the internet or world wide web 19 . The computing devices 12 are operated by users authorized by the e.g., automobile manufacturer or dealer, to access system 14 , the level of access granted being variable. Typically, a user will not have full access to the system 14 until registering with the system and providing at least some identification, the details of the registration process being outside of the scope of this application. However, prior to accessing the system, the user will have to enter at least some data, including at least first and last name, e-mail address, phone number, street address including zip code, with the system 14 including a log in screen (not shown) displayable on the user terminal 12 to allow for the entry of the data. This minimal entry of data will limit casual price shopping to preserve system 14 computing resources, and can also be used by the system to determine delivery times and dealer locations as will be described in more detail later. [0033] The host computing facility 18 , which is of course typically operated by an entity engaged in the business of providing computing services and associated software to commercial entities (manufacturers of vehicles in the present example) engaged in interstate commerce as noted above, may include one or more servers 21 for volume data and program storage, including the software application necessary to implement the system 14 , and allows for inputting, accessing, (i.e. data capture), and editing all data necessary to allow the user of, e.g., a PC 12 to select, customize, and finally purchase an automobile. At least one intelligent client associated with the servers 21 allows for limited and secure access to the servers 21 . The host computing facility 18 allows for selectively accessing the remote computing resources 16 (e.g., manufacturer's servers for aftermarket manufacturers of the various components) for performing the various tasks associated with the system 14 , the resources 16 providing data relating to price, availability, compatibility, as well as other information necessary for the implementation of the system 14 as will be explained in more detail later. System administrators associated with computing facility 18 serve as a human interface to the system 10 and perform various tasks such as upgrading software, hardware maintenance, and communicating various reports and messages to users, including those associated with the manufacturer and or dealer of automobiles, or aftermarket manufacturers, as is known in the art. [0034] Referring again to FIG. 1 , the vehicle 10 is represented as a three dimensional image which may be from an actual photograph. In any event, the image of the vehicle 10 would be made as realistic as possible using CAD/CAM techniques as is known in the art. The vehicle 10 to be customized includes many interior and exterior components. By way of an example, two such components, the grill 30 and rims 32 are to be selected for customization by the user of PC 12 . The display screen or webpage 33 displaying the selected vehicle includes various icons/textboxes to allow the user to navigate the selection and customization process. A column of textboxes 34 , 36 includes identifying indicia appropriate to the component to be considered by the user. In the present example two textboxes 34 , 36 are shown, but in practice many will be displayed corresponding to a complete list of components which can be added to the particular vehicle selected. The list of components available for any particular vehicle will of course vary, as will the textboxes 34 , 36 and the underlying links. The user can request to view a selected component by clicking (with a computer mouse or equivalent webpage navigating device available for the end user device 12 ) on a particular textbox, for example textbox 34 labeled grills, which allows the user to navigate to another webpage displaying actual images, e.g. JPEG photos, of an array of grills 30 available for the particular vehicle 10 selected. The navigation process will be a function of underlying “links”, i.e. URLs associated with data processing resources 18 , 16 of the manufacturer of the particular component selected. Clicking on the textbox 34 will thus cause the user to navigate to a webpage hosted by data processing resource 18 , the webpage having a plurality of components displayed thereon. The user can then double click on the photo of a particular one of the components whereupon a link to a complete virtual or actual image of the component is made. The image is accompanied by text data indicating price, availability, manufacturer, and model no. of the selected grill 30 and is displayed in block 35 , after the user is automatically navigated back to the webpage 33 . If, for example the user selects grills 30 , then all grills 30 available for the selected vehicle are shown, including those available from the manufacturer of the selected vehicle 10 . If the grill 30 selected is available from an aftermarket manufacturer, then the user will be navigated to a resource 16 corresponding to the aftermarket manufacturer so that the selected grill image is displayed in block 35 , though this process can be transparent to the user as is known in the art. If the user decides to add a particular grill 30 , the image of the grill 30 may be double clicked which, after returning to webpage 33 and displaying the image of the component in block 35 , also causes a display of a virtual image of the vehicle 10 with the selected grill 30 . This action is repeated for every component to be selected until the user completes the customization process. It should be noted that all aspects of the vehicle configuration will be customizable using the web interface 33 as shown in FIG. 1 including, but not limited to, vehicle color, engine size, interior treatments, rims, tires, grills, hood ornaments, spoilers etc. Also, in the case of interior treatments, which includes dashboard and console configurations, materials, trim, and seat and floor mat colors, a simulation of the vehicle interior will be shown, the display being facilitated by way of a suitable CAD/CAM program configured in accordance with the specific requirements of the system of the invention. For example, if the user chooses a full complement of oval gauges, with walnut trim, black leather seats, and gold floor mats, the display in FIG. 1 will display, with sufficient resolution and detail, the selected vehicle interior with the layout as modified by the components chosen. The particular component under consideration (i.e., the most recent component selected) will be displayed in box 35 , with the text data as described above. [0035] The image displayed in box 35 will include the estimated delivery time to the manufacturer of the vehicle 10 of the selected component. It can be appreciated that the system 14 of the invention would require some cooperation of the vehicle manufacturer with manufacturers of various aftermarket components, including compatibility of image data associated with the aftermarket components as displayed on the computing resources 16 associated with the aftermarket manufacturers, as well as compensation agreements and any other arrangements to ensure the efficient delivery of a selected component as would be apparent to one of skill in the art. The delivery time of a selected component is viewable by the user of device 12 . Also, the user can click on a particular part of the vehicle 10 as displayed in FIG. 1 to display a particular component in box 35 . For example, the user can position the navigating device on wheels 32 to display a selected component for wheels 32 in box 35 . Thus, the user can view image and availability data of each component selected in box 35 , with the default image in box 35 being the last component added. If the user is not satisfied with the delivery date or the appearance of a selected component, she can choose another component. [0036] Referring now to FIG. 3 a flowchart illustrating the method of the invention is shown. It should be noted that while the invention is implemented as software on a computer server 18 in communication with an end user device 12 , the final result, in the event of a purchase, is a customized vehicle which may be an automobile, motorcycle, RV, SUV, or boat. Thus the invention is equally applicable to virtually any commodity which is modifiable by the addition or removal of components having an impact on the overall aesthetic or functional qualities of the commodity. The term block or step are used interchangeably and are considered equivalent. The first step of the invention after the initialization of a web browser on the user device 12 is the display of the web page provided by the, e.g., manufacturer of a vehicle to be purchased, which web page prompts the user for the type and model of the vehicle to be customized as shown in block 102 . Once the user (the term user hereinafter referring to the user of the end user device 12 unless otherwise indicated) enters the identifying information as described above, the interface or webpage 33 is shown allowing for the display of the vehicle, along with the components and options such as rims 32 , wheels, grills 30 , fabric options, vehicle color options, etc. as indicated in block 104 , and described in more detail above. Also, the MSRP of the vehicle is displayed, as well as the possible delivery date in text box 39 as will be discussed in more detail later. The image of the vehicle 10 is displayed, modified in accordance with the user's selection, updated in real time also as discussed above. [0037] Decision block 106 indicates the recurring steps of selecting and viewing (step 104 ) a component on or in a virtual image of the vehicle 10 ( FIG. 1 ) until all desired corrections or changes are made. Once the user is satisfied with the vehicle 10 and the selected components as displayed in FIG. 1 , he can click the seek icon 37 which causes server 21 to initialize a final search of all relevant databases, including those databases associated with server 21 and resources 16 , and advances the system to block 108 . The server 21 database will include all components available directly from the vehicle manufacturer. The resources 16 searched by the server 21 include, but are not limited to, databases of the vehicle manufacturer subsidiaries and manufacturers of aftermarket products as shown in block 108 , to ascertain that the selected components are available as indicated during step 104 . The updated, customized vehicle displayed at step 104 ( FIG. 1 ) includes a display of the price data (MSRP), which data includes the price for individual components available as discussed above. In block 110 , the system 18 will determine, and display in FIG. 1 ( 39 ), an approximate delivery date of the customized vehicle 10 . The determination of the delivery date will be based upon a number of factors including the shipping time and delivery of selected components, and the backlog of existing orders for vehicles 10 if any. If the delivery date shown in block 110 ( FIG. 1 ) is not acceptable, then the user may navigate back to the step shown in block 104 , to determine, inter alia, which components are delaying the delivery date and perhaps choosing other components using the method as described above, before progressing again to step 106 as shown in block 112 . A key aspect of the invention is that the vehicle 10 delivery date can be advanced by selecting more readily available aftermarket components if the user so desires, with the system allowing some transparency regarding which components are delaying the delivery date as discussed above. Otherwise, if the delivery date is acceptable, the customization process is complete and the user proceeds to step 114 by clicking on the next icon 41 ( FIG. 1 ) to view participating dealers and select the most convenient dealer location 43 , 45 as seen in FIG. 4 . The dealer location will be based upon the user's geographical location which may be determined by the user entering the log in/registration data as described above, the user selecting a maximum radius to limit the display of dealers to those within a reasonable distance if desired. The user may then proceed to the financing/documentation step as shown in block 116 , by clicking on next icon 51 as seen in FIG. 4 . During this step, displayed in FIG. 5 , the user is shown a number of financing options, along with the appropriate forms for proceeding with the application for financing process, which forms are accessed by clicking on a desired option 53 , 55 . The forms presented to the user at this point will be those prepared by the selected dealer, and the vehicle price (MSRP) will be adjusted in accordance with the dealer pricing schedule. Of course, the financing documentation will include all data relevant to the dealer, already filled in the appropriate boxes/columns, such as make, model, options, price, etc. The user of course fills in the necessary finance data, such as income, desired monthly payment, etc. After selecting a desired financing option and filling out the appropriate forms, the user may then either complete the transaction by printing out (block 117 ) and physically presenting the accumulated documentation to the dealer, which documentation will include information regarding the vehicle make and model, the components and relevant part numbers selected by the user, and the financing documentation as shown in block 116 , or the user can proceed with the fully online option as shown in block 118 , if available. It can be appreciated that not all manufacturers would desire such a complex transaction to be carried out online with the possibility of interne fraud so this option may only be available to a certain class of users as determined during the log-in and registration process, with the type of verification and documentation required being solely at the discretion of the manufacturer and/or dealer. If the end user device 12 is at the dealer's store location, then the user will be limited to the physical presentation option of step 116 . If the user proceeds with the online option of step 118 by clicking on next icon 61 , then an additional interface may be presented as shown in FIG. 6 at the option of the dealer selected, which interface will allow for some degree of negotiation of the price, and all allow for the secure entry of data necessary to complete the transaction. At this point, a representative of the selected dealer may be notified by the server 18 of an ongoing negotiation, and intervene to conduct an online or telephonic negotiation to both expedite and refine the process. Methods of notification may include an internet message (IM) directed to personnel designated for continuous monitoring of online negotiations. The system 14 thus allows the dealer to expedite and streamline sales initiated by an internet user, but only after the user 12 has indicated a high level of interest in purchasing the vehicle, to avoid burdening the dealer personnel with users that are merely price shopping. Of course, the system 14 can be used to alert the dealer as soon as the dealer has been selected by the user. [0038] Once the user has completed the customization, financing, and price negotiation, if any, a final date for delivery of the vehicle 10 is established, and the user then acquires the vehicle. [0039] It is to be understood that the provided illustrative examples are by no means exhaustive of the many possible uses for my invention. [0040] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

An electronic system for the customization, visualization, integration, purchase, and acquisition of a vehicle from a vehicle manufacturer. The system is implemented on a computer server or equivalent device, where the server, operated by the manufacturer, is accessible over the internet via a suitable end-user operated computing device, the server generating a menu driven visual interface viewable on the computing device. The system allows for all aspects of a customized vehicle purchase to be performed by the user, substantially streamlining the selection and acquisition process. The system can be interfaced with third party parts databases, allowing for incorporation of parts from a variety of manufacturers.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 13/850,577, filed Mar. 26, 2013 (now U.S. Pat. No. ______), which is a continuation of U.S. patent Application No. 13/714,748, filed Dec. 14, 2012 (now U.S. Pat. No. 8,553,079), which is a continuation of U.S. patent application Ser. No. 12/700,055, filed Feb. 4, 2010, which is a continuation of U.S. patent application Ser. No. 10/866,191, filed Jun. 14, 2004, which is a continuation of U.S. patent application Ser. No. 09/433,297, filed Nov. 3, 1999 (now U.S. Pat. No. 6,750,848), which claims benefit of U.S. Provisional Application No. 60/107,652, filed Nov. 9, 1998. These applications are hereby incorporated by reference. REFERENCES TO RELATED APPLICATIONS BY THE INVENTORS [0002] U.S. patent application Ser. No. 09/138,339, filed Aug. 21, 1998. [0003] U.S. Provisional Application No. 60/056,639, filed Aug. 22, 1997. [0004] U.S. Provisional Application No. 60/059,561, filed Sep. 19, 1998. [0005] Man Machine Interfaces: Ser. No. 08/290,516, filed Aug. 15, 1994, and now U.S. Pat. No. 6,008,800. [0006] Touch TV and Other Man Machine Interfaces: Ser. No. 08/496,908, filed Jun. 29, 1995, and now U.S. Pat. No. 5,982,352. [0007] Systems for Occupant Position Sensing: Ser. No. 08/968,114, filed Nov. 12, 1997, now abandoned, which claims benefit of 60/031,256, filed Nov. 12, 1996. [0008] Target holes and corners: U.S. Ser. No. 08/203,603, filed Feb. 28, 1994, and Ser. No. 08/468,358 filed Jun. 6, 1995, now U.S. Pat. No. 5,956,417 and U.S. Pat. No. 6,044,183. [0009] Vision Target Based Assembly: U.S. Ser. No. 08/469,429, filed Jun. 6, 1995, now abandoned; Ser. No. 08/469,907, filed Jun. 6, 1995, now U.S. Pat. No. 6,301,763; Ser. No. 08/470,325, filed Jun. 6, 1995, now abandoned; and Ser. No. 08/466,294, filed Jun. 6, 1995, now abandoned. [0010] Picture Taking Method and Apparatus: Provisional Application No. 60/133,671, filed May 11, 1998. [0011] Methods and Apparatus for Man Machine Interfaces and Related Activity: Provisional Application No. 60/133,673 filed May 11, 1998. [0012] Camera Based Man-Machine Interfaces: Provisional Patent Application No. 60/142,777, filed Jul. 8, 1999. [0013] The copies of the disclosure of the above referenced applications are incorporated herein by reference. BACKGROUND OF THE INVENTION [0014] 1. Field of the Invention [0015] The invention relates to simple input devices for computers, particularly, but not necessarily, intended for use with 3-D graphically intensive activities, and operating by optically sensing object or human positions and/or orientations. The invention in many preferred embodiments, uses real time stereo photogrammetry using single or multiple TV cameras whose output is analyzed and used as input to a personal computer, typically to gather data concerning the 3D location of parts of, or objects held by, a person or persons. [0016] This continuation application seeks to provide further detail on useful embodiments for computing. One embodiment is a keyboard for a laptop computer (or stand alone keyboard for any computer) that incorporates digital TV cameras to look at points on, typically, the hand or the finger, or objects held in the hand of the user, which are used to input data to the computer. It may also or alternatively, look at the head of the user as well. [0017] Both hands or multiple fingers of each hand, or an object in one hand and fingers of the other can be simultaneously observed, as can alternate arrangements as desired. [0018] 2. Description of Related Art [0019] My referenced co-pending applications incorporated herein by reference discuss many prior art references in various pertinent fields, which form a background for this invention. BRIEF DESCRIPTION OF FIGURES [0020] FIG. 1 illustrates a laptop or other computer keyboard with cameras according to the invention located on the keyboard surface to observe objects such as fingers and hands overhead of the keyboard. [0021] FIG. 2 illustrates another keyboard embodiment using special datums or light sources such as LEDs. [0022] FIG. 3 illustrates a further finger detection system for laptop or other computer input. [0023] FIG. 4 illustrates learning, amusement, monitoring, and diagnostic methods and devices for the crib, playpen and the like. [0024] FIG. 5 illustrates a puzzle toy for young children having cut out wood characters according to the invention. [0025] FIG. 6 illustrates an improved handheld computer embodiment of the invention, in which the camera or cameras may be used to look at objects, screens and the like as well as look at the user along the lines of FIG. 1 . [0026] FIGS. 7A-B illustrate new methods for internet commerce and other activities involving remote operation with 3D virtual objects display. DESCRIPTION OF THE INVENTION [0027] FIG. 1 [0028] A laptop (or other) computer keyboard based embodiment is shown in FIG. 1 . In this case, a stereo pair of cameras 100 and 101 located on each side of the keyboard are used, desirably having cover windows 103 and 104 mounted flush with the keyboard surface 102 . The cameras are preferably pointed obliquely inward at angles Φ toward the center of the desired work volume 170 above the keyboard. In the case of cameras mounted at the rear of the keyboard (toward the display screen), these cameras are also inclined to point toward the user at an angle as well. [0029] Alternate camera locations may be used such as the positions of cameras 105 and 106 , on upper corners of screen housing 107 looking down at the top of the fingers (or hands, or objects in hand or in front of the cameras), or of cameras 108 and 109 shown. [0030] One of the referenced embodiments of the invention is to determine the pointing direction vector 160 of the user's finger (for example pointing at an object displayed on screen 107 ), or the position and orientation of an object held by the user. Alternatively, finger position data can be used to determine gestures such as pinch or grip, and other examples of relative juxtaposition of objects with respect to each other, as has been described in co-pending referenced applications. Positioning of an object or portions (such as hands or fingers of a doll) is also of use, though more for use with larger keyboards and displays. [0031] In one embodiment, shown in FIG. 2 , cameras such as 100 / 101 are used to simply look at the tip of a finger 201 (or thumb) of the user, or an object such as a ring 208 on the finger. Light from below, such as provided by single central light 122 can be used to illuminate the finger that typically looks bright under such illumination. [0032] It is also noted that the illumination is directed or concentrated in an area where the finger is typically located such as in work volume 170 . If the light is of sufficient spectral content, the natural flesh tone of the finger can be observed—and recognized by use of the color TV cameras 100 / 101 . [0033] As is typically the case, the region of the overlapping cameras viewing area is relatively isolated to the overlapping volumetric zone of their fields 170 shown due to focal lengths of their lenses and the angulation of the camera axes with respect to each other. This restricted overlap zone helps mitigate against unwanted matches in the two images due to information generated outside the zone of overlap. Thus there are no significant image matches found of other objects in the room, since the only flesh-toned object in the zone is typically the finger or fingers of the user. Or alternatively, for example, the user's hand or hands. Similarly objects or targets thereon can be distinguished by special colors or shapes. [0034] If desired, or required, motion of the fingers can be also used to further distinguish their presence vis-a-vis any static background. If for example, by subtraction of successive camera frames, the image of a particular object is determined to have moved it is determined that this is likely the object of potential interest which can be further analyzed directly to determine if is the object of interest. [0035] In case of obscuration of the fingers or objects in the hand, cameras in additional locations such as those mentioned above, can be used to solve for position if the view of one or more cameras is obscured. [0036] The use of cameras mounted on both the screen and the keyboard allows one to deal with obscurations that may occur and certain objects may or may not be advantageously delineated in one view or the other. [0037] In addition, it may be in many cases desirable to have a datum on the top of the finger as opposed to the bottom because on the bottom, it can get in the way of certain activities. In this case the sensors are required on the screen looking downward or in some other location such as off the computer entirely and located overhead has been noted in previous application. [0038] To determine finger location, a front end processor like that described in the target holes and corners co-pending application reference incorporated U.S. Ser. Nos. 08/203,603 and 08/468,358 can be used to also allow the finger shape as well as color to be detected. [0039] Finger gestures comprising a sequence of finger movements can also be detected by analyzing sequential image sets such as the motion of the finger, or one finger with respect to another such as in pinching something can be determined. Cameras 100 and 101 have been shown at the rear of the keyboard near the screen or at the front. They may mount in the middle of the keyboard or any other advantageous location. [0040] The cameras can also see one's fingers directly, to allow typing as now, but without the physical keys. One can type in space above the plane of the keyboard (or in this case plane of the cameras). This is useful for those applications where the keyboard of conventional style is too big (e.g., the hand held computer of FIG. 6 ). [0041] FIG. 2 [0042] It is also desirable for fast reliable operation to use retro-reflective materials and other materials to augment the contrast of objects used in the application. For example, a line target such as 200 can be worn on a finger 201 , and advantageously can be located if desired between two joints of the finger as shown. This allows the tip of the finger to be used to type on the keyboard without feeling unusual—the case perhaps with target material on tip of the finger. [0043] The line image detected by the camera can be provided also by a cylinder such as retroreflective cylinder 208 worn on the finger 201 which effectively becomes a line image in the field of view of each camera (assuming each camera is equipped with a sufficiently coaxial light source, typically one or more LEDs such as 210 and 211 ), can be used to solve easily using the line image pairs with the stereo cameras for the pointing direction of the finger that is often a desired result. The line, in the stereo pair of images provides the pointing direction of the finger, for example pointing at an object displayed on the screen 140 of the laptop computer 138 . [0044] FIG. 3 [0045] It is also possible to have light sources on the finger that can be utilized such as the 2 LED light sources shown in FIG. 3 . This can be used with either TV camera type sensors or with PSD type analog image position sensors as disclosed in references incorporated. [0046] In particular the ring mounted LED light sources 301 and 302 can be modulated at different frequencies that can be individually discerned by sensors imaging the sources on to a respective PSD detector. Alternatively, the sources can simply be turned on and off at different times such that the position of each point can be independently found allowing the pointing direction to be calculated from the LED point data gathered by the stereo pair of PSD based sensors. [0047] The “natural interface keyboard” here described can have cameras or other sensors located at the rear looking obliquely outward toward the front as well as inward so as to have their working volume overlap in the middle of the keyboard such as the nearly full volume over the keyboard area is accommodated. [0048] Clearly larger keyboards can have a larger working volume than one might have on a laptop. The pair of sensors used can be augmented with other sensors mounted on the screen housing. It is noted that the linked dimension afforded for calibration between the sensors located on the screen and those on the keyboard is provided by the laptop unitary construction. [0049] One can use angle sensing means such as a rotary encoder for the laptop screen tilt. Alternatively, cameras located on the screen can be used to image reference points on the keyboard as reference points to achieve this. This allows the calibration of the sensors mounted fixedly with respect to the screen with respect to the sensors and keyboard space below. It also allows one to use stereo pairs of sensors that are not in the horizontal direction (such as 101 / 102 ) but could for example be a camera sensor such as 100 on the keyboard coupled with one on the screen, such as 106 . [0050] Knowing the pointing angles of the two cameras with respect to one another allows one to solve for the 3D location of objects from the matching of the object image positions in the respective camera fields. [0051] As noted previously, it is also of interest to locate a line or cylinder type target on the finger between the first and second joints. This allows one to use the fingertip for the keyboard activity but by raising the finger up, it can be used as a line target capable of solving for the pointed direction for example. [0052] Alternatively one can use two point targets on the finger such as either retroreflective datums, colored datums such as rings or LED light sources that can also be used with PSD detectors which has also been noted in FIG. 2 . [0053] When using the cameras located for the purpose of stereo determination of the position of the fingers from their flesh tone images it is useful to follow the preprocessing capable of processing data obtained from the cameras in order to look for the finger. This can be done on both color basis and on the basis of shape as well as motion. [0054] In this invention, I have shown the use of not only cameras located on a screen looking downward or outward from the screen, but also cameras that can be used instead of or in combination with those on the screen placed essentially on the member on which the keyboard is incorporated. This allows essentially the keyboard to mounted cameras which are preferably mounted flush with the keyboard surface to be unobtrusive, and yet visually be able to see the users fingers, hands or objects held by the user and in some cases, the face of the user. [0055] This arrangement is also useful for 3D displays, for example where special synchronized glasses (e.g., the “Crystal Eyes” brand often used with Silicon Graphics work stations) are used to alternatively present right and left images to each eye. In this case the object may appear to be actually in the workspace 170 above the keyboard, and it may be manipulated by virtually grasping (pushing, pulling, etc.) it, as has been described in co-pending applications. [0056] FIG. 4 : Baby Learning and Monitoring System [0057] A baby's reaction to the mother (or father) and the mother's analysis of the baby's reaction is very important. There are many gestures of babies apparently indicated in child psychology as being quite indicative of various needs, wants, or feelings and emotions, etc. These gestures are typically made with the baby's hands. [0058] Today this is done and learned entirely by the mother being with the baby. However with an Electro-optical sensor based computer system, such as that described in co-pending applications located proximate to or even in the crib (for example), one can have the child's reactions recorded, not just in the sense of a video tape which would be too long and involved for most to use, but also in terms of the actual motions which could be computer recorded and analyzed also with the help of the mother as to what the baby's responses were. And such motions, combined with other audio and visual data can be very important to the baby's health, safety, and learning. [0059] Consider for example crib 400 with computer 408 having LCD monitor 410 and speaker 411 and camera system (single or stereo) 420 as shown, able to amuse or inform baby 430 , while at the same time recording (both visually, aurally, and in movement detected position data concerning parts of his body or objects such as rattles in his hand) his responses for any or all of the purposes of diagnosis of his state of being, remote transmission of his state, cues to various programs or images to display to him or broadcast to others, or the like. [0060] For one example, baby's motions could be used to signal a response from the TV either in the absence of the mother or with the mother watching on a remote channel. This can even be over the Internet if the mother is at work. [0061] For example, a comforting message could come up on the TV from the mother that could be prerecorded (or alternatively could actually be live with TV cameras in the mother's or father's workplace for example on a computer used by the parent) to tell the baby something reassuring or comfort the baby or whatever. Indeed the parent can be monitored using the invention and indicate something back or even control a teleoperater robotic device to give a small child something to eat or drink for example. The same applies to a disabled person. [0062] If the father or mother came up on the screen, the baby could wave at it, move its head or “talk” to it but the hand gestures may be the most important. [0063] If the mother knows what the baby is after, she can talk to baby or say something, or show something that the baby recognizes such as a doll. After a while, looking at this live one can then move to talking to the baby from some prerecorded data. [0064] What other things might we suppose? The baby for example knows to puts its hand on the mother's cheek to cause the mother to turn to it. The baby also learns some other reflexes when it is very young that it forgets when it gets older. Many of these reflexes are hand movements, and are important in communicating with the remote TV based mother representation, whether real via telepresense or from CD Rom or DVD disk (or other media, including information transmitted to the computer from afar) and for the learning of the baby's actions. [0065] Certainly just from the making the baby feel good point-of-view, it would seem like certain motherly (or fatherly, etc.) responses to certain baby actions in the form of words and images would be useful. This stops short of physical holding of the baby which is often needed, but could act as a stop gap to allow the parents to get another hour's sleep for example. [0066] As far as the baby touching things, I've discussed in other applications methods for realistic touch combined with images. This leads to a new form of touching crib mobiles that could contain video imaged and or be imaged themselves—plus if desired—touched in ways that would be far beyond any response that you could get from a normal mobile. [0067] For example, let us say there is a targeted (or otherwise TV observable) mobile 450 in the crib above the baby. Baby reaches up and touches a piece of the mobile which is sensed by the TV camera system (either from the baby's hand position, the mobile movement, or both, and a certain sound is called up by the computer, a musical note for example. Another piece of the mobile and another musical note. The mobile becomes a musical instrument for the baby that could play either notes or chords or complete passages, or any other desired programmed function. [0068] The baby can also signal things. The baby can signal using agitated movements would often mean that it's unhappy. This could be interpreted using learned movement signatures and artificial intelligence as needed by the computer to call for mother even if the baby wasn't crying. If the baby cries, that can be picked up by microphone 440 , recognized using a voice recognition system along the lines of that used in IBM Via Voice commercial product for example. And even the degree of crying can be analyzed to determine appropriate action. [0069] The computer could also be used to transmit information of this sort via the internet email to the mother who could even be at work. And until help arrives in the form of mother intervention or whatever, the computer could access a program that could display on a screen for the baby things that the baby likes and could try to soothe the baby through either images of familiar things, music or whatever. This could be useful at night when parents need sleep, and anything that would make the baby feel more comfortable would help the parents. [0070] It could also be used to allow the baby to input to the device. For example, if the baby was hungry, a picture of the bottle could be brought up on the screen. The baby then could yell for the bottle. Or if the baby needed his diaper changed, perhaps something reminiscent of that. If the baby reacts to such suggestions of his problem, this gives a lot more intelligence as to why he is crying and while mothers can generally tell right away, not everyone else can. In other words, this is pretty neat for babysitters and other members of the household so they can act more intelligently on the signals the baby is providing. [0071] Besides in the crib, the system as described can be used in conjunction with a playpen, hi-chair or other place of baby activity. [0072] As the child gets older, the invention can further be used also with more advanced activity with toys, and to take data from toy positions as well. For example, blocks, dolls, little cars, and moving toys even such as trikes, scooters, driveable toy cars and bikes with training wheels. [0073] The following figure illustrates the ability of the invention to learn, and thus to assist in the creation of toys and other things. [0074] FIG. 5 : Learning Puzzle Roy [0075] Disclosed in FIG. 5 is a puzzle toy 500 where woodcut animals such as bear 505 and lion 510 are pulled out with handle such as 511 . The child can show the animal to the camera and a computer 530 with TV camera (or cameras) 535 can recognize the shape as the animal, and provide a suitable image and sounds on screen 540 . [0076] Alternatively, and more simply, a target, or targets on the back of the animal can be used such as triangle 550 on the back of lion 511 . In either case the camera can solve for the 3D, and even 5 or 6D position and orientation of the animal object, and cause it to move accordingly on the screen as the child maneuvers it. The child can hold two animals, one in each hand and they can each be detected, even with a single camera, and be programmed in software to interact as the child wishes (or as he learns the program). [0077] This is clearly for very young children of two or three years of age. The toys have to be large so they can't be swallowed. [0078] With the invention in this manner, one can make a toy of virtually anything, for example a block. Just hold this block up, teach the computer/camera system the object and play using any program you might want to represent it and its actions. To make this block known to the system, the shape of the block, the color of the block or some code on the block can be determined. Any of those items could tell the camera which block it was, and most could give position and orientation if known. [0079] At that point, an image is called up from the computer representing that particular animal or whatever else the block is supposed to represent. Of course this can be changed in the computer to be a variety of things if this is something that is acceptable to the child. It could certainly be changed in size such as a small lion could grow into a large lion. The child could probably absorb that more than a lion changing into a giraffe for example since the block wouldn't correspond to that. The child can program or teach the system any of his blocks to be the animal he wants and that might be fun. [0080] For example, he or the child's parent could program a square to be a giraffe where as a triangle would be a lion. Maybe this could be an interesting way to get the child to learn his geometric shapes! [0081] Now the basic block held up in front of the camera system could be looked at just for what it is. As the child may move the thing toward or away from the camera system, one may get a rough sense of depth from the change in shape of the object. However this is not so easy as the object changes in shape due to any sort of rotations. [0082] Particularly interesting then is to also sense the rotations if the object so that the animal can actually move realistically in 3 Dimensions on the screen. And perhaps having the de-tuning of the shape of the movement so that the child's relatively jerky movements would not appear jerky on the screen or would not look so accentuated. Conversely of course, you can go the other way and accentuate the motions. [0083] This can, for example, be done with a line target around the edge of the object is often useful for providing position or orientation information to the TV camera based analysis software, and in making the object easier to see in reflective illumination. [0084] Aid to Speech Recognition [0085] The previous co-pending application entitled “Useful man machine interfaces and applications” referenced above, discussed the use of persons movements or positions to aid in recognizing the voice spoken by the person. [0086] In one instance, this can be achieved by simply using ones hand to indicate to the camera system of the computer that the voice recognition should start (or stop, or any other function, such as a paragraph or sentence end, etc.). [0087] Another example is to use the camera system of the invention to determine the location of the persons head (or other part), from which one can instruct a computer to preferentially evaluate the sound field in phase and amplitude of two or more spaced microphones to listen from that location—thus aiding the pickup of speech—which often times is not able to be heard well enough for computer based automatic speech recognition to occur. [0088] Digital Interactive TV [0089] As you watch TV, data can be taken from the camera system of the invention and transmitted back to the source of programming. This could include voting on a given proposition by raising your hand for example, with your hand indication transmitted. Or you could hold up 3 fingers, and the count of fingers transmitted. Or in a more extreme case, your position, or the position of an object or portion thereof could be transmitted—for example you could buy a coded object—whose code would be transmitted to indicate that you personally (having been pre-registered) had transmitted a certain packet of data. If the programming source can transmit individually to you (not possible today, but forecast for the future), then much more is possible. The actual image and voice can respond using the invention to positions and orientations of persons or objects in the room—just as in the case of prerecorded data—or one to one internet connections. This allows group activity as well. [0091] In the extreme case, full video is transmitted in both directions and total interaction of users and programming sources and each other becomes possible. [0092] An interim possibility using the invention is to have a program broadcast to many, which shifts to prerecorded DVD disc or the like driving a local image, say when your hand input causes a signal to be activated. [0093] Handwriting Authentication [0094] A referenced co-pending application illustrated the use of the invention to track the position of a pencil in three dimensional space such that the point at which the user intends the writing point to be at, can be identified and therefore used to input information, such as the intended script. [0095] As herein disclosed, this part of the invention can also be used for the purpose of determining whether or not a given person's handwriting or signature is correct. [0096] For example, consider authentication of an Internet commercial transaction. In this case, the user simply writes his name or address and the invention is used to look at the movements of his writing instrument and determine from that whether or not the signature is authentic. (A movement of one or more of his body parts might also or alternatively be employed). For example a series of frames of datum location on his pen can be taken, to determine one or more positions on it as a function of time, even to include calculating of its pointing direction, from a determined knowledge in three axes of two points along the line of the pen axis. In this case a particular pointing vector sequence “signature” would be learned for this person, and compared to later signatures. [0097] What is anticipated here is that in order to add what you might call the confirming degree of authenticity to the signature, it may not be necessary to track the signature completely. Rather one might only determine that certain aspects of the movement of the pencil are the authentic ones. One could have people write using any kind of movement, not just their signature having their name. The fact is that people are mostly used to writing their name and it would be assumed that that would be it. However, it could well be that the computer asks the user to write something else that they would then write and that particular thing would be stored in the memory. [0098] Optionally, one's voice could be recognized in conjunction with the motion signature to add further confirmation. [0099] This type of ability for the computer system at the other end of the Internet to query a writer to write a specific thing in a random fashion adds a degree of cryptographic capacity to the invention. In other words, if I can store the movements in my hand to write different things, then clearly this has some value. [0100] The important thing though is that some sort of representation of the movements of the pencil or other instrument can be detected using the invention and transmitted. [0101] FIG. 6 : Hand Held Computer [0102] FIG. 6 illustrates an improved handheld computer embodiment of the invention. For example, FIG. 8 of the provisional application referenced above entitled “camera based man machine interfaces and applications” illustrates a basic hand held device and which is a phone, or a computer or a combination thereof, or alternatively to being hand held, can be a wearable computer for example on one's wrist. [0103] In this embodiment, we further disclose the use of this device as a computer, with a major improvement being the incorporation of a camera of the device optionally in a position to look at the user, or an object held by the user—along the lines of FIG. 1 of the instant disclosure for example. [0104] Consider hand held computer 901 of FIG. 6 , incorporating a camera 902 which can optionally be rotated about axis 905 so as to look at the user or a portion thereof such as finger 906 , or at objects at which it is pointed. Optionally, and often desirably, a stereo pair of cameras to further include camera 910 can also be used. It too may rotate, as desired. Alternatively fixed cameras can be used as in FIG. 1 , and FIG. 8 of the referenced co-pending application, when physical rotation is not desired, for ruggedness, ease of use, or other reasons (noting that fixed cameras have fixed fields of view, which limit versatility in some cases). [0105] When aimed at the user, as shown, it can be used, for example, to view and obtain images of: [0106] Ones self-facial expression etc., also for image reasons, id etc., combined effect. [0107] Ones fingers (any or all), one finger to other and the like. This in turn allows conversing with the computer in a form of sign language which can replace the keyboard of a conventional computer. [0108] One or more objects in one's hand. Includes a pencil or pen, and thus can be used rather than having a special touch screen and pencil if the pencil itself is tracked as disclosed in the above figure. It also allows small children to use the device, and those who cannot hold an ordinary stylus. [0109] One's Gestures. [0110] The camera 902 (and 910 if used, and if desired), can also be optionally rotated and used to viewpoints in space ahead of the device, as shown in dotted lines 902 a. In this position for example it can be used for the purposes described in the previous application. It can also be used to observe or point at (using optional laser pointer 930 ) points such as 935 on a wall, or a mounted LCD or projection display such as 940 on a wall or elsewhere such as on the back of an airline seat. [0111] With this feature of the invention, there is no requirement to carry a computer display with you as with a infrared connection (not shown) such as known in the art one can also transmit all normal control information to the display control computer 951 . As displays become ubiquitous, this makes increasing sense—otherwise the displays get bigger the computers smaller trend doesn't make sense if they need to be dragged around together. As one walks into a room, one uses the display or displays in that room (which might themselves be interconnected). [0112] The camera unit 902 can sense the location of the display in space relative to the handheld computer, using for example the four points 955 - 958 on the corners of the display as references. This allows the handheld device to become an accurate pointer for objects displayed on the screen, including control icons. And it allows the objects on the screen to be sensed directly by the camera—if one does not have the capability to spatially synchronize and coordinate the display driver with the handheld computer. [0113] The camera can also be used to see gestures of others, as well as the user, and to acquire raw video images of objects in its field. [0114] A reverse situation also exists where the cameras can be on the wall mounted display, such as cameras 980 and 981 can be used to look at the handheld computer module 901 and determine its position and orientation relative to the display. [0115] Note that a camera such as 902 , looking at you the user, if attached to hand held unit, always has reference frame of that unit. If one works with a screen on a wall, one can aim the handheld unit with camera at it, and determine its reference frame to the handheld unit. Also can have two cameras operating together, one looking at wall thing, other at you (as 902 and 902 a ) in this manner, one can dynamically compare ref frames of the display to the human input means in determining display parameters. This can be done in real time, and if so one can actually wave the handheld unit around while still imputing accurate data to the display using ones fingers, objects or whatever. [0116] Use of a laser pointer such as 930 incorporated into the handheld unit has also been disclosed in the referenced co-pending applications. For example, a camera on the hand held computer unit such as 902 viewing in direction 902 a would look at laser spot such as 990 (which might or might not have come from the computers own laser pointer 930 ) on the wall display say, and recognized by color and size/shape reference to edge of screen, and to projected spots on screen. [0117] FIGS. 7A-B : Internet and Other Remote Applications [0118] FIG. 7A illustrates new methods for internet commerce and other activities involving remote operation with 3D virtual objects displayed on a screen. This application also illustrates the ability of the invention to prevent computer vision eye strain. [0119] Let us first consider the operation of the invention over the internet as it exists today in highly bandwidth limited form dependent on ordinary phone lines for the most part. In this case it is highly desirable to transmit just the locations or pointing vectors of portions (typically determined by stereo photo-grammetry of the invention) of human users or objects associated therewith to a remote location, to allow the remote computer 10 to modify the image or sound transmitted back to the user. [0120] Another issue is the internet time delay, which can exist in varying degrees, and is more noticeable, the higher resolution of the imagery transmitted. In this case, a preferred arrangement is to have real time transmission of minimal position and vector data (using no more bandwidth than voice), and to transmit back to the user, quasi stationary images at good resolution. Transmission of low resolution near real time images common in internet telephony today, does not convey the natural feeling desired for many commercial applications to now be discussed. As bandwidth becomes more plentiful these restrictions are eased. [0121] Let us consider the problem posed of getting information from the internet of today. A user 1000 can go to a virtual library displayed on screen 1001 controlled by computer 1002 where one sees a group 1010 of books on stacks. Using the invention as described herein and incorporated referenced applications to determine my hand and finger locations, I the user, can point at a book such as 1014 in a computer sensed manner, or even reach out and “grab” a book, such as 1020 (dotted lines) apparently generated in 3D in front of me. [0122] My pointing, or my reach and grab is in real time, and the vector (such as the pointing direction of ones finger at the book on the screen, or the position and orientation closing vectors of one's forefinger and thumb to grab the 3D image 1020 of the book) indicating the book in question created is transmitted back by internet means to the remote computer 1030 which determines that I have grabbed the book entitled War and Peace from the virtual shelf. A picture of the book coming off the shelf is then generated using fast 3D graphical imagery such as the Merlin VR package available today from Digital Immersion company of Sudbury, Ontario. This picture (and the original picture of the books on the shelves) can be retransmitted over the internet at low resolution (but sufficient speed) to give a feeling of immediacy to the user. Or alternatively, the imagery can be generated locally at higher resolution using the software package resident in the local computer 1002 which receives key commands from the distant computer 1030 . [0123] After the book has been “received” by the user, it then can be opened automatically to the cover page for example under control of the computer, or the users 10 hands can pretend to open it, and the sensed hands instruct the remote (or local, depending on version) computer to do so. A surrogate book such as 1040 can also be used to give the user a tactile feel of a book, even though the real book in questions pages will be viewed on the display screen 1001 . One difference to this could be if the screen 1001 depicting the books were life size, like real stacks. Then one might wish to go over to a surrogate book incorporating a separate display screen—just as one would in a real library, go to a reading table after removing a book from a stack. [0124] Net Grocery stores have already appeared, and similar applications concern picking groceries off of the shelf of a virtual supermarket, and filling ones shopping cart. For that matter, any store where it is desired to show the merchandise in the very manner people are accustomed to seeing it, namely on shelves or racks, generally as one walks down an aisle, or fumbles through a rack of clothes for example. In each case, the invention, which also can optionally use voice input, as if to talk to a clothing sales person, can be used to monitor the person's positions and gestures. [0125] The invention in this mode can also be used to allow one to peruse much larger objects. For example, to buy a car (or walk through a house, say) over the internet, one can lift the hood, look inside, etc., all by using the invention to monitor the 3D position of your head or hands and move the image of the car presented accordingly. If the image is presented substantially life-size, then one can be monitored as one physically walks around the car in one's room say, with the image changing accordingly. In other words just as today. [0126] Note that while the image can be apparently life-size using virtual reality glasses, the natural movements one is accustomed to in buying a car are not present. This invention makes such a natural situation possible (though it can also be used with such glasses as well). [0127] It is noted that the invention also comprehends adding a force based function to a feedback to your hands, such that it feels like you lifted the hood, or grabbed the book, say. For this purpose holding a surrogate object as described in co-pending applications could be useful, in this case providing force feedback to the object. [0128] If one looks at internet commerce today, some big applications have turned out 10 to be clothes and books. Clothes are by far the largest expenditure item, and let's look closer at this. [0129] Consider too a virtual mannequin, which can also have measurements of a remote shopper. For example, consider diagram 78 , where a woman's measurements are inputted by known means such as a keyboard 1050 over the internet to a CAD program in computer 1055 , which creates on display screen 1056 a 3D representation of a mannequin 1059 having the woman's shape in the home computer 1060 . As she selects a dress 1065 to try on, the dress which let's say comes in 10 sizes, 5 to 15, is virtually “tried on” the virtual mannequin and the woman 1070 looks at the screen 1056 and determines the fit of a standard size 12 dress. She can rapidly select larger or smaller sizes and decide which she thinks looks and/or fits better. [0130] Optionally, she can signal to the computer to rotate the image in any direction, and can look at it from different angles up or down as well, simply doing a rotation in the computer. This signaling can be conventional using for example a mouse, or can be using TV based sensing aspects of the invention such as employing camera 1070 also as shown in FIG. 1 for example. In another such case, she can reach out with her finger 1075 for example, and push or pull in a virtual manner the material, using the camera to sense the direction of her finger. Or she can touch herself at the points where the material should be taken up or let out, with the camera system sensing the locations of touch (typically requiring at least a stereo pair of cameras or other electro-optical system capable of determining where her fingertip is in 3D space. Note that a surrogate for the tried on dress in this case, could be the dress she has on, which is touched in the location desired on the displayed dress. [0131] The standard size dress can then be altered and shipped to her, or the requisite modifications can be made in the CAD program, and a special dress cut out and sewed which would fit better. [0132] A person can also use her hands via the TV cameras of the invention to determine hand location relative to the display to take clothes off a virtual manikin which could have a representation of any person real or imaginary. Alternatively she can remotely reach out using the invention to a virtual rack of clothes such as 1090 , take an object off the rack, and put it on the manikin. This is particularly natural in near life-size representation, just like being in a store or other venue. This ability of the invention to bring real life experience to computer shopping and other activity that is a major advantage. [0133] The user can also feel the texture of the cloth if suitable haptic devices are 15 available to the user, which can be activated remotely by the virtual clothing program, or other type of program. [0134] Modifications of the invention herein disclosed will occur to persons skilled in the art, and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.

A method for enhancing a well-being of a small child or baby utilizes at least one TV camera positioned to observe one or more points on the child or an object associated with the child. Signals from the TV camera are outputted to a computer, which analyzes the output signals to determine a position or movement of the child or child associated object. The determined position or movement is then compared to preprogrammed criteria in the computer to determine a correlation or importance, and thereby to provide data to the child.

BACKGROUND OF THE INVENTION The present invention relates in general to a variable height support apparatus and more specifically to a variable height support apparatus for use in combination with a solid object dispenser such as a pill or capsule dispenser. The variable height support of this invention is an improvement in that it allows a dispenser for filling blister packs with pills or capsules to be easily modified to dispense pills or capsules of various thicknesses without reconfiguration or modification of the dispenser apparatus. With the conventional pill or capsule card filling apparatus it is generally necessary to modify or reconfigure the apparatus whenever changing the size, and particularly the thickness of the pills or capsules to be placed in the receptacle portions of the conventional pill or capsule card or blister pack. Blister packs, consisting of a molded semi-rigid base covered and sealed by a rupturable material, are commonly used for packaging pills and capsules. Blister packs are used both by pharmaceutical companies which manufacture the drugs and package them in blister packs, and by smaller health care facilities which use the blister packs for packaging individual doses. These blister packs are also manufactured by companies in the business of providing unfilled blister packs for filling by third parties. Many conventional dispensers are manufactured to dispense only one size or shape of pill or capsule. Such dispensers are commonly used by pharmaceutical companies which are geared to produce the filled pill or capsule cards or blister packages in large quantities for a particular pill or capsule. However, for smaller manufacturers or health care facilities it is desirable to be able to produce and fill the cards or blister packages with pills or capsules of various sizes and shapes and use a minimum number of different dispenser. A single, easily modified dispenser is particularly suited to this portion of the industry. Conventional dispensers are available which can be modified to dispense pills or capsules of varying shapes and sizes. However, these conventional dispensers do not include the improvements included in the present invention as described more fully herein and illustrated in the accompanying drawings. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pill or capsule dispensing support structure in which the height of pill or capsule guiding or transfer member of the structure is easily varied. Another object of the present invention is to provide a support structure in which the height of the aforementioned structure is varied in 1/32" units. A further object of the present invention is to provide a variable height support structure which is economically constructed with a minimum of parts to avoid expensive repair or replacement. Still another object of the present invention is to provide a variable height support structure which is suitable for use in combination with a solid object dispenser. Still a further object of the present invention is to provide a dispenser capable of filling blister packs with pills or capsules of various thicknesses by simply turning a knob. To accomplish the foregoing and other objects of this invention there is provided a variable height support structure for use in combination with a dispenser. The variable height support structure comprises a work surface supported by an asymmetrical cam, the cam and corresponding axle being supported by a pillow block. The axle protrudes beyond the support structure and includes an end knob to facilitate turning. When the knob is turned, a different portion of the asymmetric cams are presented to their respective contact portions of the work surface, resulting in movement of the work surface up or down. The cams are preferably designed to move the work surface in increments of 1/32", corresponding to the standard variation in pill or capsule thickness. The cams are held in place at the stated increments by an indexing device comprising a spring-loaded ball bearing mounted within the pillow block and semi-spherical recesses on the cam face. The work surface is held in level vertical alignment with the dispenser by telescoping support members at the corners of the structure. When used with a dispenser, the height of the work surface is adjusted to correspond to the thickness of the pill or capsule being dispensed. A conventional paddle containing the blister packs to be filled is inserted into the structure and supported by the work surface. Once a blister pack is filled, then the paddle is used to move the blister pack to a heat sealing device. The dispenser device includes a bin for holding the bulk pills or capsules to be dispensed and rotating brushes to keep the pills in motion. The pills or capsules are swept by the brushes through apertures or openings in a stationary plate which forms the base of the bin. A spring-loaded shuttle plate which has openings corresponding to the size or thickness and shape of the pill or capsule is positioned underneath the apertures of openings in the stationary plate such that the pills or capsules fall into the openings. The shuttle plate then moves horizontally until the openings are aligned with apertures in a dispensing plate located beneath the shuttle plate. The dispensing plate includes apertures which are selected to correspond to the shape of the pill or capsule being dispensed. These apertures in the dispensing plate are aligned with the openings in the blister packs. It will be understood that the number of apertures and their arrangement or pattern in the dispensing plate will vary depending upon the number of receptacles and their arrangement in the receiving blister pack. The blister packs are held in position by a paddle plate. The pills or capsules drop through the dispensing plate and into the blister packs. The paddle with the now filled blister package is removed and replaced with an unfilled blister pack or another paddle with an unfilled blister pack is placed in position within the apparatus of the present invention. These and other objects and features of the present invention will be better understood and appreciated from the following detailed description of preferred embodiments thereof, selected for purposes of illustration and shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the support structure of the present invention in combination with a solid object dispenser; FIG. 2 is a perspective view of the support structure of FIG. 1; FIG. 3 is a plan view of the support structure FIG. 2 with the work surface in dashed lines to show the cam and axle which vary the height of the work surface; FIG. 4 is a cross section of the structure of FIG. 2 taken along line 4--4 in FIG. 2; FIG. 5 is a front elevation of the structure of FIG. 2 with the work surface in its lowered position; FIG. 6 is a front elevation of the structure of FIG. 2 with the work surface in its raised position; FIG. 7 is a front perspective view of the cam assembly; FIG. 8 is a rear perspective view of the cam assembly illustrating the indexing device recesses on the cam face; FIG. 9 is a cross sectional view of the cam assembly showing a spring-loaded ball-bearing assembly; FIG. 10 is a plan view further illustrating the shuttle plate spring device and the dispenser surfaces; FIGS. 11 and 12 are plan views of apertured stationary plates located below the bin used in the dispenser of FIG. 1, including FIG. 11 illustrating a stationary plate having elongated slots for use in filling a conventional 30 or 31 pill or capsule blister package and FIG. 12 illustrating a stationary plate having apertures or openings arranged for filling a conventional 90 pill or capsule blister pack; FIGS. 13, 14 and 15 are plan views of the shuttle apertured plate openings, used in the dispenser of the present invention depicted in FIG. 1 with FIG. 13 illustrating the pill or capsule shaped aperture for filling a conventional 30 pill or capsule blister package, FIG. 14 illustrating an apertured plate for filling a conventional blister package with 90 relatively small pills or capsules, and FIG. 15 illustrating an apertured plate for filling a conventional blister package with 90 relatively larger sized pills or capsules; FIG. 16, 17 and 18 are plan views of a plurality of dispensing plates used in the dispenser shown in FIG. 1, wherein FIG. 16 illustrates elongated slots or openings for filling a conventional blister package with 30 or 31 pills or capsules, and FIG. 17 and FIG. 18 illustrate apertured plates for dispensing either 90 relatively small or relatively larger pills or capsules; FIG. 19 is a typical end view of the dispensing plate illustrating one embodiment of a shoulder arrangement on the sides of the dispensing plate in which the shoulder facilitates the insertion of the dispensing plate into the supporting frame member; and FIG. 20 illustrates a view of a blister pack paddle used in concert with the other plates by an operator of the dispenser structure and supported by the dispenser structure of FIG. 1. DETAILED DESCRIPTION Referring now to the drawings there is shown a preferred embodiment for the variable height support structure for the dispenser of this invention. The support structure is described in connection with a solid object dispenser, more particularly a dispenser for dispensing pills or capsules into blister packs. The support structure allows variation of the height of a work surface by use of asymmetric cams supporting the work surface. As the axle bearing the cams is turned, a portion of the cam having a different radius is presented to the work surface. The variation in cam radius results in a variation of the work surface height. The support structure of the present invention is particularly adapted for use with a pill or capsule dispenser. The location of the adjustable work surface that supports the dispenser plate is determined so as to allow the blister packs to be filled efficiently. It will be understood that the vertical location of the work relative to the shuttle plate surface can be changed as required as the thickness, shape or size of the pill or capsule being dispensed requires. The support structure of the present invention allows the work surface height to be adjusted in 1/32" increments by turning the axle-mounted knob. This obviates the need to completely disassemble or substantially reconfigure the dispenser to accommodate pills or capsules of varying thicknesses. The drawings show a preferred embodiment of the variable height support structure generally designated 10 in combination with a solid object dispenser generally designated 12 in FIG. 1. The presently preferred dispenser 12 has a dispenser base 17 in which the support structure 10 is housed. Base 17 includes a U-shaped cover portion 14 with one or more moveable tabs 15. The cover 14 supports a circular collar 16 which acts as a bin to hold a pill, capsule, pills or capsules to be dispensed. The tabs 15 hold the collar 16 in place. Mixer rods 18 having brushes 20 rotate to move and mix the pill, capsules, pills or capsules within the collar bin 16 with the rotating brushes. The rods 18 are rotated by a motor 22, and the rotation speed is controlled by the user through a selector 24. It will be understood that a motor driven brush arrangement of this type is conventional. As shown more clearly in FIG. 10, the U-shaped cover 14 has a recessed ledge 82 around its inner perimeter. The ledge 82 further includes two notches 84 and 86 located preferably at the mid-point along each of the "legs" of the U-shaped cover 14. A spring device 88 is mounted on the base portion of the cover 14 and extends horizontally over the recessed ledge 82. The support structure 10 is shown in more detail in FIG. 2 where the front face of dispenser base 17 has been removed. Structure 10 includes a work surface 28 which is framed by a U-shaped upwardly extending portion 26. Extending inwardly from the top of the U-shaped extension portion 26 is a second framing portion 90. The work surface 28 is preferably retained in level alignment by telescoping alignment members generally designated 29 located at the four corners of work surface 28. The alignment members 29 include a guide base 30, an inner telescoping member 32 and an outer telescoping member 34. The alignment members 29 are mounted on a base 36. It will be understood that other alignment arrangements are readily substituted for that shown with the preferred embodiment. The work surface 28 rests on the asymmetric cams 40, 41. The work surface 28 is shown in dashed lines in FIG. 3 to illustrate and clarify the location of the cam structure. It will be understood that the actual shape of the cam portion of the cam structure may be altered in the event that more than the 1/4" inch adjustment is required. This also underscores the fact that the present invention is not limited to the dispensing of pills or capsules in order to fill blister packs for later dispensing. The cams and the corresponding axle 42 are preferably supported by a pillow block 44 mounted to the base 36. A portion of the axle 42 extends beyond the structure 10 and includes a handle or a knob 46 to allow a user to turn the axle 42 and therefore the cams 40, 41. These cams 40, 41 and the axle 42 construction is shown in cross section in FIG. 4. The cams 40, 41 in the illustrated embodiment are asymmetric in shape. In the presently preferred embodiment one quadrant of both of the cams 40, 41 have a gradually increasing radius, the radius at its longest point being 1/4" longer than at its shortest point. The knob 46 turns the cams so that the radius of cams 40, 41 presented to the work surface increases in discreet 1/32" increments. This corresponds to the industry standard thicknesses of pills and capsules. These increments are accomplished by an indexing device as shown in FIG. 8 and FIG. 9. The rear cam 41 preferably includes semi-spherical recesses on the rear face of the cam. The portion of the corresponding pillow block adjacent to the cam face or the rear cam includes a spring-loaded ball bearing sized correspondingly to fit within the recesses on the cam face. As the knob 46 turns the cam 41, the ball-bearing 100 exerts pressure on the cam face. As a cam recess 94 is presented to the ball bearing 100, the spring 104 forces the ball-bearing 100 into the recess 94, "locking" the cam in position. By turning the knob 46 again, the force applied forces the ball bearing 100 back out of the recess 94. The ball bearing 100 then presses against the cam face until another recess 94 is presented. The nine cam recesses are located in relation to the cam and spring-loaded ball bearing so that each "locked" position corresponds to a 1/32" variation in the cam radius being presented to the work surface. FIG. 5 shows the cams 40, 41 positioned so that the shortest radius is presented to and supports work surface 28 so that the work surface 28 is in it lowest position. FIG. 6 shows the cams 40, 41 positioned so that the longest radius is presented to and supports the work surface 28 so that the work surface 28 is in its uppermost position. In use, the preferred combination dispenser 12 and the support structure 10 includes a desired number of replaceable plates and four replaceable plates are illustrated, each selected for a particular application. The uppermost plate 50, shown in FIGS. 11 and 12, as preferred for the described embodiment, is octagonal and forms the base of the bin 16. Plate 50 includes one or more apertures 52 through which the pill, pills, capsules or pills are swept by the rotating brushes 20. FIG. 11 illustrates a plate 50 with apertures 52 for ultimately dispensing pills or capsules into blister packages of either thirty (30) or thirty-one (31) openings. FIG. 12 shows a plate for use when the blister package has ninety (90) pills or capsules. It will be understood by one skilled in the art that the plate 50 is readily modified for use with the desired blister packages. A shuttle plate 64 shown in FIG. 13, FIG. 14 and FIG. 15 has openings 66 generally corresponding to the size and/or thickness of the pills or capsules to be dispensed. FIG. 13 generally illustrates a shuttle plate 64 used when filling blister packages of thirty (30) pills or capsules. It will be understood that this shuttle plate can be further modified to add another opening for use when filling blister packages of thirty-one (31) pills or capsules. FIG. 14 generally illustrates a shuttle plate 64 for use in filling blister packages of ninety (90) pills or capsules. FIG. 15 generally illustrates another embodiment of a shuttle plate 64 for use when filling blister packages of ninety (90) pills or capsules. The shuttle plate 64 includes projections or ears 70 which fit into receiving notches 84, 86 of the recessed ledge 82. The projections or ears are of a width sufficiently less than the notches 84, 86 so as to allow movement of the shuttle plate 64 in a front-to-back horizontal direction. A dispensing plate 56, shown in FIGS. 16, 17 and 18, has apertures 58 corresponding generally to the shape of the pills or capsules being dispensed. The plate 56 of FIG. 16 is used when dispensing pills or capsules into blister packages of either thirty (30) or thirty-one (31) count, while the dispensing plates illustrated in FIGS. 17 and 18 are shown to illustrate the dispensing plates used when dispensing relatively smaller and larger pills or capsules into ninety (90) count blister packages. Each dispensing plate 56 preferably includes a shoulder portion 92 along opposing outer side edges as generally illustrated in FIG. 19. When assembled the upper horizontal portion of each of the shoulder portions 92 are intended to rest on framing portion 90. This arrangement is one preferred embodiment for maintaining the desired alignment. It will be understood that other alignment arrangements are possible. It will be understood from filling conventional blister packages or cards with conventional filling devices that the shape of the apertures of this and the other plates may vary without effecting the scope of the present invention. It will be further understood that it would not be possible to illustrate every combination of number and size of holes. A particular arrangement can readily be formed when the size and number of pills or capsules and the blister package or card arrangement is known. Thus, one skilled in the art will now realize how the present invention can be readily adapted for as yet unknown pill or capsule size and number. The fourth plate is a conventional paddle 76 as shown in FIG. 20. The paddle 76 supports a blister pack 78, including one or more molded blister package recesses 30 to be filled. The plates are assembled as follows. Each blister pack 78 to be filled is positioned on its respective paddle 76 and the paddle is inserted. The paddle 76 is supported by the adjustable height work surface 28 of structure 10. The dispensing plate 56 is positioned above the paddle 76, with its shoulders 92 resting in the notches 92 of framing portion 90. The height of the support structure 10 is then adjusted as described below to correspond to the thickness of the pills or capsules to be dispensed. The shuttle plate 64 is positioned above the dispenser plate 56. The spring device 88 is mounted relative to the recessed ledge 82 and is depressed as the shuttle plate 64 is moved into place. The projections 70 are aligned with and fit into the notches 96 defined by the recessed ledge 82. When the force used to depress the spring device 88 is released, the bias of the spring device 88 forces the shuttle plate 64 back toward the front of the dispenser 12. The movement or displacement of the shuttle plate 64 is limited by the interference between the edges of the notches 96 and the projections 70 located in the notches. The upper plate 50 is then mounted on the U-shaped cover surface 14, between the cover surface 14 and the bin 16 which is held in place by tabs 15. To dispense pills or capsules, the appropriate plates form a group of available plates that are selected and assembled as previously described. The distance between the work surface 28 supporting the dispensing plate 56 and the shuttle plate 64 is then adjusted to allow for the thickness of the plates and the size and shape of the pills or capsules being dispensed. Without the aforementioned adjustment, the thickness of the particular adjacent plates chosen for the job and the thickness and/or shape and/or size of the pills or capsules intended to be dispensed could interfere with or even prevent the intended dispensing and filling of blister packages. Furthermore, this vertical height adjustment allows the apparatus of the present invention to be used for the same count but different size and/or shape pills or capsules to be dispensed with only the vertical height adjusted as taught herein. The height of the support structure 10 is adjusted by turning the knob 46 on axle 42, the 1/32" increments in the height of work surface 28 corresponding to the standard variation in pill or capsule thickness. It will be understood that other increments and total adjustment may vary depending upon the application in which the present invention is used. The bulk volume of the object to be dispensed is located in the collar bin 16. The rotation speed of the mixing rods 18 and brushes 20 is then selected when the mixing motor is turned on. The speed of the motor and brushes may be changed during the process if necessary to effect the movement of the pills or capsules within the bin 16. The brushes then sweep the pills or capsules over the apertures or openings of the first plate 50, and gravity acts on the pills or capsules which then fall through the apertures 52 and into the apertures or openings 66 of the shuttle plate 64 when the shuttle plate is in a receiving position. The shuttle plate 64 is then moved by applying a force against the spring mechanism. When the shuttle plate openings 66 are in vertical alignment with the dispensing plate 56 and its openings or apertures 58, then the pills or capsules fall through the dispensing plate 56 and into the molded recesses 30 of the blister package 78. The shuttle plate is then allowed to move back to its original biased position by the spring device. The filled blister packages 78 in the paddle 76 are replaced with another un-filled blister packages 78, which can be accomplished by either replacing the blister package or the entire paddle 76 and blister package combination. A cover 80 is heat sealed over the blister package to complete the process.* This is a brief summary of the operation of conventional dispensing apparatus as well as the apparatus of the present invention. The operation of the present invention is described below. When a pill or capsule of a differing shape or thickness is to be dispensed, the appropriate plates are inserted and the work surface height adjusted correspondingly. The ability to adjust the height of the work surface as shown and described herein provides an efficient and time saving manner in which the pills or capsules of varying thicknesses and shapes are allowed to be dispensed by the same machine without completely dismantling or extensively modifying the dispenser 10. From the foregoing description those skilled in the art will appreciate that all of the objects of the present invention are realized. A support structure is provided in which the height of the structure is easily varied. For the application disclosed herein the structure provides a surface work height that can be varied in 1/32" increments. The structure provided uses a minimum of parts, making the structure economical to produce and maintain. The structure is suitable for use in combination with a solid object dispenser, and thereby provides a dispenser capable of being modified to dispense objects of various sizes and shapes without disassembly of the dispenser. When used in combination with a pill or capsule dispenser, the structure provides a dispenser capable of filling blister packs with pills or capsules of varying thicknesses by simply turning a knob. While a specific embodiment has been shown and described, many variations are possible. The dispensing mechanism disclosed herein is preferred, but any suitable mechanism may be substituted. The 1/32" increments of height variation are presently useful in drug dispensing, but the height variations may be modified for the particular application. The combination dispenser is not limited to use with blister packs and may be used to fill any suitable container. While the telescoping members which keep the work surface level are presently preferred, any suitable leveling means may be substituted. The cam configuration disclosed is presently preferred, but any shape cam which provides proper height adjustment may be utilized. Further the structure should not be read as to be limited to the axle/pillow block construction disclosed herein. Any suitable indexing mechanism may be utilized to lock the cam in the desired position. The pill or capsule dispensing method is described utilizing manual control of the axle position and the shuttle plate movement. Any or all portions of the method can be mechanized without departing from the applicant's invention. Having described the invention in detail, those skilled in the art will appreciated that modifications may be made of the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiment illustrated and described. Rather, it is intended that the scope of this invention be determined by the appended claims and their equivalents.

A variable height support structure is provided for use in combination with a solid object dispenser such as a pill or capsule dispenser. The height of the support structure is varied by the use of asymmetrical cam designed to move the support structure surface in discreet units. The apparatus allows a dispenser to fill blister packs with pills or capsules of various shapes and thicknesses without dispenser component reconfiguration or modification or replacement.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (PDP) and, more particularly, to a composition of plasma display panel. 2. Description of the Background Art In general, a plasma display panel (PDP) device receives much attention as a next-generation display device together with a thin film transistor (TFT), a liquid crystal display (LCD), an EL (Electro-Luminescence) device, an FED (Field Emission Display) and the like. The PDP is a display device which uses a luminescent phenomenon according to an energy difference made when red, green and blue fluorescent materials are changed from an excited state to a ground state after being excited by 147 nm of ultraviolet rays which are generated as a He+X3 gas or N3+X3 gas is discharged from a discharge cell isolated by a barrier rib. Thanks to its properties of facilitation in manufacturing from a simple structure, a high luminance, a high light emitting efficiency, a memory function, a high non-linearity, a 160° or larger optical angular field and the like, the PDP display device is anticipated to occupy a 40″ or wider large-scale display device markets. A structure of the conventional PDP will now be described with reference to FIG. 1 . FIG. 1 is a sectional view showing a structure of a conventional PDP. As shown in FIG. 1 , the conventional PDP includes: a lower insulation layer 20 formed on a lower glass substrate 21 ; an address electrode 22 formed at a predetermined portion on the lower insulation layer 20 ; a lower dielectric layer 19 formed on the address electrode 22 and the lower insulation layer 20 ; an isolation wall 17 defined in a predetermined portion on the lower dielectric layer 19 in order to divide each discharging cell; a black matrix layer 23 formed on the isolation wall 17 ; a fluorescent layer 18 formed with a predetermined thickness on the side of the black matrix layer 23 and the isolation wall 17 and on the lower dielectric layer 19 , and receiving ultraviolet ray and emitting each red, green and blue visible rays; a glass substrate 11 ; a sustain electrode 12 formed at a predetermined portion on the upper glass substrate 11 in a manner of vertically intersecting the address electrode 22 ; a bus electrode 12 formed on a predetermined portion on the sustain electrode 12 ; a first upper dielectric layer 14 formed on the bus electrode 13 , the sustain electrode 12 and the upper glass substrate 11 ; a second upper dielectric layer 15 formed on the first upper dielectric layer 14 ; and a protection layer (MgO) 16 formed on the second upper dielectric layer 15 in order to protect the second upper dielectric layer 15 . The first and second upper dielectric layers 14 and 15 are called upper dielectric layers. The operation of the conventional PDP will now be described. First, as the upper glass substrate 11 and the lower glass substrate 21 of the conventional PDP, an SLS (Soda-Lime Silicate) glass substrate is used. The lower insulation layer 20 is positioned on the lower glass substrate 21 , the SLS glass substrate, and the address electrode 22 is positioned on the lower insulation layer 20 . The lower dielectric layer 19 positioned on the address electrode 22 and the lower insulation layer 20 blocks visible rays emitted toward the lower glass substrate 21 . In order to increase the luminous efficacy, a dielectric layer having a high reflectance is used as the lower dielectric layer 19 . The lower dielectric layer 19 , a translucent dielectric layer with a reflectance of 60% or above, minimizes loss of light. The fluorescent layer 18 is formed by laminating in a sequential order of red, green and blue fluorescent materials. A specific wavelength of visible ray is emitted depending on an intensity of an ultraviolet ray according to plasma generated between the isolation walls 17 . Meanwhile, at a lower surface of the upper glass substrate 11 , the SLS glass substrate, there are formed the sustain electrode 12 positioned to vertically intersect the address electrode 22 and the bus electrode 13 positioned on the sustain electrode 12 . And upper dielectric layers 14 and 15 with an excellent light transmittance are positioned on the bus electrode 13 . The protection layer 16 is positioned on the upper dielectric layer 15 in order to prevent the upper dielectric layer 15 from being damaged due to generation of plasma. Herein, since the first upper dielectric layer 14 is directly contacted with the sustain electrode 12 and the bus electrode 13 , it must have a high softening temperature in order to avoid a chemical reaction with the sustain electrode 12 and the bus electrode 13 . In addition, since the second upper dielectric layer 15 is expected to have a high smoothness because the protection layer 16 is formed thereon, its softening temperature must be lower by scores of ° C. than the first upper dielectric layer 14 . Commonly, the PDP display device has a problem of jitter occurrence. The jitter phenomenon, which occurs as discharging is delayed for a certain time for a specific applied scan pulse, causes a mis-discharging and interferes a high speed driving. The jitter phenomenon is affected mainly by a surface state of the protection layer (MgO) and a crystallinity, an electric permittivity (that is, a dielectric constant) and thickness of each layer, a structure and a gap of isolation walls and electrodes, a driving method, a type and a content of a discharging gas, and the like. Especially, Xe has a low diffusion rate in a discharging space, so if the Xe content is increased in order to obtain a high efficacy characteristics, there is higher probability that the jitter phenomenon occurs. Therefore, in the conventional art, in order to solve the problem of the mis-discharging due to the jitter phenomenon, usually, an electric permittivity of the upper dielectric layer and the lower dielectric layer is increased or their thickness is reduced. In general, the upper dielectric layer and the lower dielectric layer of the PDP has an electric permittivity of about 12˜15 range, and especially, in case of the lower dielectric layer, because it contains TiO 2 powders for increasing the reflectance, it has a higher electric permittivity. However, if the electric permittivity is increased by about twice, a discharge voltage is degraded due to the increase in the capacitance, and thus, about 20% of the overall jitter is reduced. In addition, the jitter characteristics is also changed due to a change in the thickness of the upper dielectric layer and the lower dielectric layer of the PDP. For example, if the gap between the upper electrodes 12 and 13 and the lower electrode 22 narrows as the thickness of the upper dielectric layer and the lower dielectric layer of the PDP is reduced, the discharge voltage would be dropped and thus the jitter can be reduced. The lower dielectric layer and the upper dielectric layer are made of a material having PbO as a principal component with an electric permittivity of about 12˜15, and the gap between the upper electrode and the lower electrode is maintained at about 100 μm. The fabrication method of the lower dielectric layer 19 and the upper dielectric layers 14 and 15 will now be described in detail. The lower dielectric layer is formed as follows: Mixed powders, in which scores of % of oxide in a powder state such as TiO 2 or Al 2 O 3 having a particle diameter of below 2 μm is mixed for improving reflection characteristics and controlling an electric permittivity, is mixed with an organic solvent to produce a paste with a viscosity of about 40000˜50000 cps, and the paste is printed/fired, thereby forming the lower dielectric layer. In this case, the firing temperature is usually at the range of 550˜600° C., and the thickness of the lower dielectric layer is about 20 μm. The upper dielectric layer is formed as follows: a paste obtained by mixing an organic binder is coated to boro-silicate glass (BSG) powder with a size of a particle diameter of 1 μm˜2 μm and containing about 40% of Pb in a screen printing method, and then, the coated paste is fired at a temperature of 550° C.˜580° C. Characteristics change in the jitter according to the change in the electric permittivity will now be described with reference to FIGS. 2A and 2B . FIG. 2A shows jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 14, and FIG. 2B illustrates jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 25. As shown in FIGS. 2A and 2B , if the electric permittivity is changed from 14 to 25, an operation speed is increased from 1.25 μs to 1.14 μs due to the increase in the capacitance, and according to which the overall jitter is reduced by about 11%. However, since a withstand voltage is reduced according to the increase in the electric permittivity, there is a limitation in increasing the electric permittivity of the PbO-based dielectric material (the material of the upper dielectric layer and the lower dielectric layer). In addition, in the case of increasing the capacitance by reducing the thickness of the material having the same electric permittivity, a problem arises that the conventional dielectric can not withstand the withstand voltage of about 560V. To sum up, as stated above, the dielectric layer of the conventional PDP has the following problem. That is, since the dielectric layer is made of the PbO-based dielectric material, if the electric permittivity of the dielectric is increased in order to reduce the jitter, the withstand voltage would be reduced. Thus, the electric permittivity of the dielectric can not be increased to its maximum. In addition, if the thickness of the upper dielectric layer and the lower dielectric layer is reduced, the withstand voltage would be lowered down, causing the problem that jitter can not be effectively reduced, and thus, a high speed driving is hardly performed. Other conventional PDPs and their fabrication methods are disclosed in the U.S. Pat. No. 5,838,106 issued on Nov. 17, 1998, a U.S. Pat. No. 6,242,859 issued on Jun. 5, 2001, and a U.S. Pat. No. 6,599,851 issued on Jul. 29, 2003. SUMMARY OF THE INVENTION Therefore, one object of the present invention is to provide a composition of a plasma display panel (PDP) capable of effectively reducing a jitter. Another object of the present invention is to provide a composition of a PDP capable of preventing jitter occurrence and mis-discharging by increasing an electric permittivity of a dielectric to its maximum and increasing a capacitance. Still another object of the present invention is to provide a composition of a PDP capable of heightening a luminance and an efficiency by reflecting a portion of a visible ray radiated from a fluorescent material. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a composition of a PDP containing a ferroelectric transparent ceramics material. To achieve the above object, there is also provided a composition of a PDP, including: a lower dielectric layer containing a ferroelectric transparent ceramics material; an upper dielectric layer containing the ferroelectric transparent ceramics material; and a fluorescent material with the ferroelectric transparent ceramics material mixed therein or having a ferroelectric transparent ceramics thin film. To achieve the above object, there is also provided a ferroelectric transparent ceramics material contained in a composition of a PDP is at least one of (Pb—La)(ZrTi)O 3 , (Pb,Bi)—(ZrTi)O 3 , (Pb,La)—(HfTi)O 3 , (Pb,Ba)—(ZrTi)O 3 , (Sr,Ca)—(LiNbTi)O 3 , LiTaO 3 , SrTiO 3 , La2Ti 2 O 7 , LiNbO 3 , (Pb,La)—(MgNbZtTi)O 3 , (Pb,Ba)—(LaNb)O 3 , (Sr,Ba)—Nb 2 O 3 , K(Ta,Nb)O 3 , (Sr,Ba,La)—(Nb 2 O 6 ), NaTiO 3 , MgTiO 3 , BaTiO 3 , SrZrO 3 or KnbO 3 . The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: FIG. 1 is a sectional view showing a structure of a PDP in accordance with a conventional art; FIG. 2A shows jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 14; FIG. 2B illustrates jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 25; and FIG. 3 illustrates ferroelectric transparent ceramics materials applied in the present invention and their characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. A preferred embodiment of a composition of a PDP that is capable of effectively reducing a jitter by containing a ferroelectric transparent ceramics material thereto will now be described. Namely, preferred embodiments of a composition of a PDP capable of increasing an electric permittivity of a dielectric of a PDP to its maximum by containing the ferroelectric transparent ceramics material, preventing a jitter occurrence and a mis-discharging by increasing a capacitance, and improving a luminance and an efficiency by reflecting a portion of a visible ray radiated from a fluorescent material, will now be described. Herein, increase in the capacitance would lead to reduction of a jitter, which results in preventing of a mis-discharging generated when the PDP is at a low temperature or at a high temperature. In addition, in the present invention, a ferroelectric transparent ceramics material having a high withstand voltage, a high electric permittivity (more than 1000), and a high dielectric strength is applied to the upper and lower dielectrics constituting the PDP device, to thereby increasing a capacitance and enhancing a resistance. Moreover, the ferroelectric transparent ceramics material is also applied to a fluorescent material in order to increase the capacitance, and a visible ray reflection is induced to increase luminance and efficiency of the PDP. Preferably, the PDP comprises a dielectric layer and a phosphor layer including a ferroelectric transparent ceramics material. FIG. 3 illustrates ferroelectric transparent ceramics materials applied in the present invention and their characteristics. The materials as shown in FIG. 3 has a 1000 or higher electric permittivity, a 70% or higher visible ray transmittance, and a 10 6 /m or higher dielectric strength (not shown). Herein, since the electric permittivity, the ferroelectric transparent ceramics material applied in the present invention is higher than 1000, the jitter can be effectively reduced even with the less amount of ferroelectric transparent ceramics material. Among the materials, (Pb, Bi)—(ZrTi)O 3 , (Pb, La)—(MgNbZrTi)O 3 , (Pb,Ba)—(LaNb)O 3 are transparent materials with a transmittance of almost 100% while having the high electric permittivity (higher than 1700), so they can be also applied to the upper dielectric of the PDP device. Various embodiments in which the ferroelectric transparent ceramics material is applied to the PDP to reduce the jitter and thus prevent mis-discharging will now be described. First Embodiment In the first embodiment, at least one of ferroelectric transparent ceramics materials of FIG. 3 is applied to the lower dielectric of the PDP. And the ferroelectric transparent ceramics powder is mixed in the conventional lower dielectric material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional lower dielectric layer to increase a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the lower dielectric material. When the ferroelectric transparent ceramics powder is mixed in the lower dielectric material, the ferroelectric transparent ceramics powder with a particle diameter of a few μm is mixed in a range of 1 weight %˜20 weight % in parent glass powder. The ratio of the lower dielectric composition has been obtained by assuming the weight of the lower dielectric layer is 100 wt %. Thereafter, the mixed powder is formed to a paste with a viscosity of about 40000˜50000, which is then printed and fired to form the lower dielectric layer. When a ferroelectric transparent ceramics thin film is formed on the lower dielectric layer, a lower dielectric layer is formed thinner than the thickness of the conventional lower dielectric layer and the ferroelectric transparent ceramics material is coated with a thickness of thousands of Å at the surface of the thin lower dielectric layer or embedded in the lower dielectric layer by E-beam or sputtering. Namely, by forming the ferroelectric transparent ceramics thin film on the lower dielectric layer, the electric permittivity of the lower dielectric can be improved. In addition, by firing the ferroelectric transparent ceramics powder, the dielectric tissue can become denser, so that a life span of the device can be increased. Second Embodiment In a second embodiment of the present invention, at least one of ferroelectric transparent ceramics materials shown in FIG. 3 is applied to the upper dielectric of the PDP. In addition, the ferroelectric transparent ceramics powder is mixed in the conventional upper dielectric material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional upper dielectric layer in order to increase a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the upper dielectric material. When the ferroelectric transparent ceramics powder is mixed in the lower dielectric material, the ferroelectric transparent ceramics powder with a particle diameter of a few nm is mixed in a range of 1 wt %˜5 wt % in parent glass powder. The ratio of the upper dielectric composition has been obtained by assuming the weight of the upper dielectric layer is 100 wt %. Thereafter, the mixed powder is formed to a paste with a viscosity of about 40000˜50000, which is then printed and fired to form the lower dielectric layer. A ferroelectric transparent ceramics thin film is formed in the same manner as in the conventional art. That is, an upper dielectric layer is formed, on which the ferroelectric transparent ceramics material is coated with a thickness of scores of ˜hundreds of Å. Namely, by forming the ferroelectric transparent ceramics thin film on the upper dielectric layer, the electric permittivity of the upper dielectric can be improved. Preferably, the ferroelectric transparent ceramics material used to heighten the electric permittivity of the upper dielectric is selected from the group consisting of (Pb,Bi)—(ZrTi)O 3 , (Pb,La)—(MgNbZrTi)O 3 , (Pb,Ba)—(LaNb)O 3 which have an extremely high transparent. Third Embodiment In the third embodiment of the present invention, at least one of ferroelectric transparent ceramics material shown in FIG. 3 is applied to a fluorescent material of the PDP. The ferroelectric transparent ceramics material is mixed in power form to a conventional fluorescent material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional fluorescent material, to thereby increasing a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the fluorescent material. When the ferroelectric transparent ceramics powder is mixed to the fluorescent material, the fine ferroelectric transparent ceramics powder with a particle diameter of a few nm is mixed in a range of 1 wt %˜10 wt % in the fluorescent material powder. The ratio of the fluorescent material composition has been obtained by assuming the weight of the fluorescent layer is 100 wt %. When the ferroelectric transparent ceramics thin film is formed on the fluorescent layer, the ferroelectric transparent ceramics thin film is formed with a thickness of below 100 Å at the surface of the conventional fluorescent layer in an E-beam or a Sol-Gel method. That is, with the ferroelectric transparent ceramics thin film thereon, the fluorescent material can discharge a secondary electron and increase a surface charge, so that a mis-discharge occurrence can be reduced. In this respect, if the ferroelectric transparent ceramics thin film is too thick, the ferroelectric transparent ceramics thin film is to absorb ultraviolet rays, reducing the luminance of the PDP. Thus, it is preferred that the ferroelectric transparent ceramics thin film has the thickness of below 100 Å. In the present invention, by applying one of the first to third embodiment to the PDP, the electric permittivity of the PDP device can be increased, and accordingly, the capacitance can be also increased. In addition, because the ferroelectric transparent ceramics material used in the present invention has a high dielectric strength, a discharge withstand voltage can be heightened. Therefore, as the capacitance is increased, the jitter can be reduced, and thus, a mis-discharge occurrence rate can be reduced. Moreover, because the ferroelectric transparent ceramics material can reflect a portion of the visible ray radiated from the fluorescent material, the strength of the discharged visible ray can be increased. As so far described, by mixing the ferroelectric transparent ceramics powder to the upper dielectric or/and lower dielectric material or by forming the ferroelectric transparent ceramics thin film on the upper dielectric or/and lower dielectric, the electric permittivity of the upper and lower dielectric can be heightened. In addition, because the electric permittivity of the upper and lower dielectric is heightened, the capacitance is increased, the jitter is reduced, and the mis-discharge occurrence rate can be considerably reduced. Moreover, by mixing the ferroelectric transparent ceramics powder to the fluorescent material or by forming the ferroelectric transparent ceramics thin film on the fluorescent material, the visible ray radiated from the fluorescent material can be partially reflected, so that the luminance and efficiency of the PDP can be also enhanced. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

A composition of a plasma display panel (PDP) is disclosed. In order to effectively reduce a jitter, the composition contains a ferroelectric transparent ceramics material.

TECHNICAL FIELD OF THE INVENTION [0001] This invention relates to digital equalizer technology and more particularly to fractional-spaced equalizers that are preceded by a MF. BACKGROUND OF THE INVENTION [0002] In terms of suppressing out-of-band distortion and canceling multi-path ISI, the standard design of most digital receivers cascades a MF with an adaptive equalizer. The MF usually takes the form of a square-root raised cosine (RRC) response in order to maximize SNR while the adaptive equalizer often operates as a fractional-spaced equalizer (FSE) to allow inverse modeling of the propagation channel across the full spectral band, as apposed to only at pass-band frequencies in the symbol-spaced equalizer. [0003] In modern receivers the transmitter's pulse-shaping process re-proportions the spectral energy of the base-band signal such that the major spectral components occupy the low-frequency band while the minor spectral lobes are made to occupy the high frequency band. The band-limited representation of the transmitted signal infers that channel inversion at out-of-band frequencies is only as important to restoring full-received SNR as to the extent that the signal's high frequency spectral components are important to representing the distortion-less transmitted modulation. [0004] In terms of suppressing such out-of-band distortion signals as CW jamming the FSE has historically relied upon both the recursion of its ISI-canceling operation and on the out-of-band attenuation characteristics of the MF preceding it. If the source of the distortion is thermal noise, however, the FSE must rely exclusively on the MF as the equalizer's spectral side-lobe levels are not well defined, are susceptible to variations in the adaptation constant, and therefore, cannot suppress the noise prior to decimation of the signal to the symbol rate. [0005] With the importance of multi-path ISI cancellation relatively unimportant at out-of-band frequencies and with the pre-FSE RRC MF providing suppression of out-of-band interference, the responsibilities of the FSE's out-of-band mask have remained limited to the cancellation of excess adjacent channel interference not suppressed by the MF. It is noted that both the pre-FSE RRC MF and FSE are digital filters that operate at the same sample rate and whose responsibilities across the frequency band are approximately decoupled. Because of this, both filters can be combined into a single filter if control over the FSE's spectral mask can sustain well-defined side-lobes that are immune to changes in the equalizer's adaptation constant. [0006] This suggests a single filter implementation for the cascade design. From the point of hardware, a cascading of successive digital filters demands that separate bank of FPGA multipliers must be used to service the demands of each filter in the cascade chain. A single filter implementation of the traditional RRC MF plus FSE cascade design reduces cost as similar hardware components can be used to service the processing of associated with each. Although an increase in computational complexity must result when two separate processes are combined to conserve hardware, many options present themselves to minimize this increase. Consequently, reductions in both computational complexity and power consumption over that required for the traditional cascade design are possible. [0007] Accordingly, it is one objective of the present invention to provide a FSE that can simultaneously affect control over the equalizer's pass-band, roll-off, and side-lobe characteristics using a technique of constrained optimization so as to form a joint ISI-cancelling and MF update that can achieve the received SNR performance of the state-of-the-art cascade pre-FSE RRC MF plus FSE design. [0008] It is another object of the present invention to provide a FSE that implements a time-multiplexing architecture that enables a single bank of multiplier elements to perform the inner product computations associated with both the ISI-canceling and MF updates within the confines of a constrained optimization update, the purpose to provide for reduced hardware complexity over that of the state-of-the-art cascade pre-FSE RRC MF plus FSE design. [0009] It is the further object of the present invention to provide a FSE that operates as a joint ISI-canceling and MF FSE where the error associated with ISI-cancellation may be derived from any number of existing algorithms within the confines of the constrained optimization update of the present invention. [0010] It is the further object of the present invention to interject the process of time-domain windowing of the constraint waveform into the constrained optimization update so as to minimize the increase in computational complexity incurred from the introduction of the time-multiplexing architecture. [0011] It is the further object of the present invention to provide a FSE operating as a joint ISI-canceling and MF FSE where the rate at which the equalizer's weights are updated in accordance with the MF processing is controlled via an algorithm to minimize computational workload. [0012] It is the further object of the present invention to provide a FSE operating as a joint ISI-canceling and MF adaptive equalizer which implements an initialization of the equalizer's FF weights using a selected set of coefficients of an RRC MF, the intent of which is to reduce the acquisition time of the MF characteristics of the FSE's steady-state joint inverse channel and MF function. [0013] It is the further object of the present invention to provide a FSE operating as a joint and MF FSE under a constrained optimization update when the FSE is partitioned as a poly-phase process. SUMMARY OF THE INVENTION [0014] These and other problems have been solved by combining the pre-FSE RRC MF and the FSE into a single filter joint process FSE that controls the spectral side-lobe behavior of the equalizer while simultaneously maintaining control over the equalizer's spectral pass-band and roll-off characteristics in accordance with the criterion for cancellation of ISI. [0015] To accomplish this, the gradient descent algorithm of the standard unconstrained FSE, which is responsible for driving the ISI-cancellation process, was modified to incorporate a constraint via the Lagrange multiplier technique. The constraint is defined to be a restriction that the equalizer's weights be orthogonal to a waveform whose major spectral components reside at out-of-band frequencies. If the FSE is operated as a base-band equalizer then out-of-band refers to the high frequency band, and if FSE is operated as a band-pass equalizer, out-of-band refers to that portion of the frequency band not occupied by the signal's major spectral components. [0016] To generate the orthogonality between the equalizer's weights and the out-of-band signal the inner product of these two time sequences is computed and subtracted from a desired orthogonality target on an iteration-by-iteration basis. The difference is scaled and then used to update the equalizer's weights in a direction so as to minimize the error. The orthogonality target is a scalar β of value less than 1.0 which forces the recursion of the constraint update to generate a low-pass process of the FSE at out-of-band frequencies. As a result, the spectral side-lobe development of the FSE is controlled so as to generate a low-pass process. The error between the measured orthogonality and targeted orthogonality is termed the constraint error and the high frequency signal is termed the constraint waveform. [0017] Thus, the modified FSE updates the equalizer's weights twice per equalizer iteration—once in accordance with the minimization of the mean-squared error associated with ISI cancellation and the second time in accordance with the criterion for the added constraint. The modified equalizer is termed the joint ISI-canceling and MF adaptive equalizer, and because of the development of well-defined spectral side-lobes at steady-state, this joint process equalizer provides for robust RRC MF processing as well as simultaneous channel inversion. [0018] The primary technical advantage of the present invention is that from the configuration of the linearly constrained algorithm driving joint process equalizer a time-multiplexing architecture is employed to allow a single bank of multiplier elements to service two inner product computations, that associated with the ISI cancellation and that associated with the added constraint for the MF processing. A single bank of multipliers servicing the needs of both ISI cancellation and MF processing contrasts with the two separate banks of multipliers required in the traditional cascade design, and therefore, the present invention conserves hardware in the system design. [0019] The present invention pertains to the creation of a joint ISI-canceling and MF process for any FSE that is sampled at more than 1-sample-per-symbol and satisfies the Nyquist criterion. Although a FSE that is sampled exactly at the Nyquist rate can sufficiently perform full band channel inversion, FSEs are often sampled above the Nyquist rate at 2-samples-per-symbol (or twice the transmitted symbol rate) in order to simplify the subsequent task of down-sampling to the symbol rate. Hence, a preferred embodiment of the present invention is designed to operate the constrained FSE at twice the symbol rate. In this case, the decimation device at the output of the equalizer takes the form of a 2:1 commutator. [0020] The time-multiplexing structure of the present invention remains unchanged regardless of the choice of the preferred embodiment for the FSE's sampling rate. For example, the constrained joint ISI-canceling and MF FSE operating at 2-samples-per-symbol performs a time-share of a single bank of multiplier elements with the samples of the two sequences accessing the multiplier bank, either the input data and the equalizer's weights or the equalizer's weights and the constraint waveform, separated in time at half-intervals of the transmitted symbol rate, or T sym /2. In an alternate embodiment, the joint ISI-canceling and MF FSE can be sampled at less than 2-samples-per-symbol if the Nyquist criterion is satisfied. Here, the time-multiplexing scheme is still based upon a time-share of a single bank of multiplier elements, but now with the samples of the two sequences accessing the multiplier bank separated in time at fractional intervals less than T sym /2. Thus, although the number of multiplier elements contained within the single bank increases as the FSE is sampled at larger rates, the time-multiplexing architecture of the present invention still provides for a conservation of hardware. [0021] As previously mentioned, the constrained update of the present invention works in conjunction with an update responsible for inversion of the propagation channel. Amongst the various existing configurations for the algorithm that generates the error associated with channel inversion the constrained update of present invention is generally used with, but is not exclusive to, three different channel inversion updates: a training sequence update, a decision-based update, and a statistically based update. Used in conjunction with the newly formed linearly constrained algorithm, these three updates, as well as others not mentioned here, form embodiments of the present invention. [0022] In the training sequence embodiment the error associated with ISI-cancellation is formed from the difference between the equalized signal and a known training sequence. In an alternate embodiment, a decision device, or slicer, forms the error as the difference between the equalized signal and the slicer's output, which is a quantized version of equalized signal. A third embodiment of the present invention forms this error as the scaled difference between the power of the equalized signal and a parameter describing the statistical properties of the original transmitted modulated signal. [0023] A decision-directed configuration for the channel inversion error algorithm is often used in conjunction with a decision-feedback update for robust cancellation of ISI. Hence, a preferred embodiment of the present invention uses the joint ISI-canceling and MF linearly constrained update within the configuration of a decision-feedback equalizer. [0024] Another technical advantage of the present invention is that the joint ISI-canceling and MF constrained update can be applied to a FSE that is partitioned as a poly-phase process. The polyphase decomposition of the standard FSE embeds the M:1 decimator normally occurring at the output of the equalizer to within the FSE using the Nobel Identity. As a result, the multiplier bank is partitioned into M multiplier sub-banks, each containing half the total multipliers of the non-partitioned multiplier bank. Although the workload per-output-point of the poly-phase partitioned FSE is greater than that of the non-poly-phase partitioned FSE by a factor of M, the poly-phase configuration commutates every M-th input sample of the distorted waveform to only one of the M sub-banks. Thus, the situation in the non-poly-phase FSE in which every input sample is processed by every equalizer weight is avoided in the poly-phase configured FSE. With regard to the present invention the linearly constrained poly-phase FSE is designed to form a joint ISI-canceling and MF process by computing M additional inner products associated with the constraint update. In the preferred embodiment of the present invention where M=2 the joint ISI-canceling and MF poly-phase FSE is able to conserve the hardware associated with the RRC MF's multiplier elements at the expense of four times the workload of the standard non-poly-phase configured unconstrained FSE. [0025] A further technical advantage of the present invention is that when the constraint waveform is defined as a frequency dependent sinusoid residing in the high frequency band, the linearly constrained update may be modified to determine the most minimal duty cycle of the sinusoid required to saturate performance. In this embodiment the time-series of the high frequency sinusoidal signal is time-domain windowed with a digital window function so as to render the samples farthest from the midpoint of the total duty cycle with negligible importance as compared to the most central samples. The net effect is that the samples of negligible amplitude need not contribute in the inner product computation associated with the constraint update. This reduces the computational complexity and improves power efficiency. [0026] It has been determined that the constraint, windowed or not windowed, need not contribute an update of the equalizer's weights at all iterations. Thus, the joint process equalizer may be designed with a switch to control at which iterations an update of the equalizer's weights associated with the MF processing is to occur. This also results in a reduction in the number of computations and the operational power needed to run the joint process equalizer. [0027] Since the equalizer's impulse response at steady-state is to be a composite of both the inverse channel model and RRC MF, initialization of the equalizer with the RRC MF taps attains half the final solution from the start. Hence, initialization reduces acquisition time of the MF characteristics, which allows the MF processing to be partially eliminated sooner in the update. [0028] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the joint ISI-canceling and MF adaptive equalizer that follows may be better understood. Additional features and advantages of this joint process equalizer will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purpose of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0029] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [0030] [0030]FIG. 1 is a high-level block diagram of a state-of-the-art MF plus FSE cascade system; [0031] [0031]FIG. 2 is a composite high-level/detailed block diagram of a state-of-the-art MF plus FSE cascade (non-poly-phase partitioned) system; [0032] [0032]FIG. 3 is a detailed block diagram of a preferred embodiment of the algorithm responsible for adjusting the error associated with channel inversion of the state-of-the-art MF plus FSE cascade system; [0033] [0033]FIG. 4 is a detailed block diagram of a preferred embodiment of the weight update algorithm of the state-of-the-art MF plus FSE cascade system; [0034] [0034]FIG. 5 is a high-level/detailed block diagram of the joint ISI-canceling and MF adaptive equalizer operating at 2-samples-per-symbol (M=2) in accordance with a preferred embodiment of the present invention; [0035] [0035]FIG. 6 is a detailed block diagram of the algorithm that generates samples of the constraint waveform in accordance with a preferred embodiment of the present invention; [0036] [0036]FIG. 7 is a detailed block diagram of the constraint error adjustment algorithm in accordance with a preferred embodiment of the present invention; [0037] [0037]FIG. 8 is a detailed block diagram of the rate control algorithm for the constraint update of the equalizer weights in accordance with a preferred embodiment of the present invention; [0038] [0038]FIG. 9 is a detailed block diagram of the algorithm that generates the channel inversion error which utilizes a training sequence-based update in accordance with a preferred embodiment of the present invention; [0039] [0039]FIG. 10 is a detailed block diagram of the algorithm that generates channel inversion error which utilizes a decision-directed update in accordance with a preferred embodiment of the present invention; [0040] [0040]FIG. 11 is a detailed block diagram of the algorithm that generates the channel inversion error which utilizes a blind update via the constant modulus algorithm (CMA), in accordance with a preferred embodiment of the present invention; [0041] [0041]FIG. 12 is a detailed block diagram of the algorithm that calculates the modulus factor of the blind CMA update, in accordance with a preferred embodiment of the present invention; [0042] [0042]FIG. 13 is a detailed block diagram of the algorithm which performs a decision-feedback update of the joint ISI-canceling and MF equalizer in accordance with a preferred embodiment of the present invention; [0043] [0043]FIG. 14 is a detailed block diagram of the algorithm which performs a windowing of the constraint waveform using a single window function in accordance with a alternate embodiment of the present invention; [0044] [0044]FIG. 15 is a detailed block diagram of an of the algorithm which performs a windowing of the constraint waveform using a window derived from a composite of many window functions in accordance with an alternate embodiment of the present invention; [0045] [0045]FIG. 16 is a detailed block diagram of the algorithm that performs an initialization of the contents of the equalizer FF weight register bank using the pre-FSE RRC MF taps in accordance with a preferred embodiment of the present invention; and [0046] [0046]FIG. 17 is a detailed block diagram of the polyphase configuration of the joint ISI-canceling and MF adaptive equalizer in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PRIOR ART [0047] Before discussing the joint ISI-canceling and MF adaptive digital equalizer, it will be useful to discuss the state-of-the-art equalizer and MF cascade design. [0048] There are no known joint ISI-canceling and MF adaptive digital equalizer configurations that permit control the spectral side-lobes of the FSE so as to generate a RRC MF state across the full spectral band of the equalizer, and so, the state-of-the-art is defined to be the design in FIG. 1, an RRC MF 101 cascaded with a FSE 102 . [0049] [0049]FIG. 2 depicts a detailed block diagram representation of FIG. 2 showing the state of the art MF plus FSE cascade filter system operating at M-samples-per-symbol (M times the symbol rate). [0050] The process is as follows. Samples of the distorted input waveform contained within a data register bank 201 associated with the RRC MF processing are shifted to the right by one register position. The sample of distorted waveform is input to the first (far left) position of the MF data register bank 201 . The contents of the MF data register bank 201 then engage the contents of an RRC MF weight register bank 202 , which stores the RRC MF coefficients, in an inner product computation using a bank of multiplier elements 203 and a bank of summation nodes 204 . This inner product IP represents a sample of the post-filtered pre-equalized signal. [0051] Next, the contents of the equalizer data register bank 205 , storing the previous samples of the post-filtered and pre-equalized signal, is shifted to the right by one register position. The sample of the previously computed inner product IP is input to the first register position of the equalizer data register bank 205 . The contents of the equalizer data register bank 205 then engage the contents of the equalizer weight register bank 206 , storing the current values of the equalizer's weights, in an inner product computation using a bank of multiplier elements 207 and a bank of summation nodes 208 . This inner product represents a sample of the equalized signal sampled at M-samples-per-symbol. [0052] The equalized sample is then passed to a M:1 commutator 209 which decimates the equalized signal to the symbol rate. The decimated signal is then passed to an algorithm ALG-ISI-ERR 210 that forms the error needed to drive the weights in accordance with criterion for ISI cancellation. Three different state-of-the-art configurations for ALG-ISI-ERR 210 are based upon a training sequence, a decision device, or a statistically based update. These configurations will be presented in detail during the description of the embodiments of the present invention. [0053] Next, the error from ALG-ISI-ERR is delivered to an algorithm ALG- 1 211 that transforms the error into an adjustment signal used to update the equalizer's weights in accordance with the criterion for channel inversion. ALG- 1 211 refers to one of any number of algorithms that can transform the error into a signal capable of controlling the adaptation of the equalizer's weights. [0054] One possible configuration for ALG- 1 211 is shown in FIG. 3 and consists of a complex conjugation operator 301 , a scalar adaptation constant μ 302 , and a multiplier 303 . The adaptation constant μ 302 multiplies the ISI equalization error to form a product representing an adjustment signal for the weight update associated with the channel inversion process. The operating range for the adaptation constant μ 302 is 0<μ<μ crit   [1] [0055] where the critical value μ crit is inversely proportional to the energy of the samples of distorted signal contained with in the equalizer data register bank 201 (ref. FIG. 2) at the current iteration. [0056] Continuing with the process flow of FIG. 2, the adjustment signal produced at the output of ALG- 1 211 is then delivered to an algorithm ALG- 2 212 which updates the contents of the equalizer weight register bank 206 . ALG- 2 212 refers to one of any number of algorithms that can make use of an adjustment signal to update the contents of the equalizer weight register bank 206 . [0057] One possible configuration for ALG- 2 212 is shown in FIG. 4. The sample of adjustment signal formed from the output of ALG- 1 212 (ref. FIG. 2) multiplies the contents of the equalizer data register bank 205 (ref. FIG. 2) using a bank of multiplier elements 401 . The resulting bank of products is added to the current contents of the equalizer weight register bank 206 (ref. FIG. 2) using a bank of summing nodes 402 . The bank of sums produced is stored in the equalizer weight register bank 206 (ref. FIG. 2). [0058] As a specific example of the equalizer's FF weight update, the contents of the first (far left) register of the equalizer data register bank 205 (ref. FIG. 2) multiplies the adjustment signal produced from ALG- 1 212 (ref. FIG. 2) using the first (far left) multiplier of the multiplier bank 401 . The product adds to the first (far left) register position of the equalizer weight resister bank 206 (ref. FIG. 2) using first (far left) summing node of the bank of summing nodes 402 and the sum is stored in the first register position of the equalizer weight register bank 206 (ref. FIG. 2). The process continues with the updates associated with the next successive register positions of the equalizer weight register bank 206 (ref. FIG. 2). [0059] Retuning to the processing in FIG. 2, after updating the contents of the equalizer weight register bank, the entire processing of the MF and FSE cascade system repeats with the contents of the MF data register bank 201 shifted to the right by one position to prepare for the next pre-filtered sample to be input. DETAILED DESCRIPTION OF THE INVENTION [0060] [0060]FIG. 5 depicts a detailed block diagram of the joint ISI-canceling and MF adaptive equalized in accordance with a preferred embodiment of the present invention. FIG. 5 indicates the time-multiplexing architecture in which a single multiplier bank 504 is utilized to perform two separate inner product computations, that associated with the channel inversion update and that related to MF processing. In this embodiment the equalizer operates at 2-samples-per-symbol (twice the symbol rate M=2); [0061] Elements currently residing within a data register bank 501 are shifted to the right by one position. A sample of the distorted input waveform is then loaded into the first position of the data register bank 501 . At time t_ 1 , after the current distorted sample enters the first data register position, switch S 1 502 is closed to allow the contents of the data register bank 501 to engage the contents of a second register bank 503 , storing values of the equalizer's feedforward (FF) weights, in an inner product using a bank of complex multiplier elements 504 and summation nodes 505 . This inner product represents the current sample estimate of the equalized signal. Samples of the equalized signal calculated from the previous inner product are then passed through a 2:1 commutator 506 , which discards every other sample to decimate to the symbol rate. The samples of decimated signal are then delivered to switch S 1 502 . Switch S 1 502 in this position prohibits the inner product samples associated with the MF processing from entering the signal processing chain associated with the channel inversion process. With switch S 1 502 closed, samples of the equalized signal are delivered to an algorithm ALG-ISI-ERR 507 to form the error signal associated with the channel inversion update. [0062] The error signal associated with the channel inversion is then delivered to an algorithm ALG- 1 508 that transforms the error into an adjustment signal used to update the equalizer's weights in accordance with the criterion for channel inversion. ALG- 1 508 refers to one of any number of algorithms that can control the adaptation of the equalizer's weights. [0063] [0063]FIG. 3 illustrates a detailed block diagram of ALG- 1 508 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0064] Referencing FIG. 5, the adjustment signal formed at the output of ALG- 1 508 is then passed to switch S 1 502 . In this position, switch S 1 502 permits an update of the equalizer's weights when the adjustment signal is derived from the channel inversion process and prevents the channel inversion error adjustment signal from updating the weights when the present invention switches its mode of operation to the MF processing. With switch S 1 502 in a closed position, the adjustment signal derived from ALG- 1 508 is delivered to algorithm ALG- 2 509 which performs an update of the contents of the equalizer's FF weight register bank 503 . ALG- 2 509 refers to one of any number of algorithms that can control the adaptation of the equalizer's weights. [0065] [0065]FIG. 4 illustrates a detailed block diagram of ALG- 2 509 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0066] This completes the ISI-cancellation process of the present invention for the current iteration. [0067] Next, the MF processing is initiated. A third register bank 510 of the present invention stores samples of a signal defining samples of the constraint waveform. This waveform represents a signal whose major spectral components reside in the high frequency band and pertains to any function that can become uncorrelated with the equalizer's impulse response within the constrained optimization algorithm so as to transform the equalizer's spectral side-lobes into a robust spectral mask. [0068] A preferred embodiment of the present invention defines the constraint waveform as a set of independent complex sinusoids, each residing above the quarter-sample rate. For example, suppose the i-th constraint sinusoid in the set {i=1,2, . . . , N} is defined as c i ( k )= A exp{U (2π f i k +φ i )}  [2] [0069] The terms A, f, and φ refer to the constraint sinusoid's amplitude frequency, and phase. The frequency changes with time (equalizer iteration n) through index i so as to sweep out the entire out-of-band frequency band. i =( n− 1)( mod ) N+ 1  [ 3 ] [0070] The total number of independent sinusoids N is determined by trial and error tuning to maximize the full-received SNR. A preferred embodiment of the present invention spaces the complex tones at equidistant frequency intervals starting at the spectral nulls of the pre-FSE RRC MF and ending at the half-sampling rate. [0071] Other embodiments may increment the frequency as in a ramping function or FM sweep (linear variation with iteration index n), or higher order non-linear variations. The constraint waveform may also be defined to be a real sinusoid or a real cosinusoid. Sinusoidal amplitude A may take on any value above zero, A>0, or may take on a time-varying format A(t) if desired. An arbitrary phase either random or deterministic φ can be included or can be derived from many phases φ i . With respect to the constraint vector sinusoidal tap index k ranges from 1 to L where L is the number of equalizer coefficients. [0072] Referring back to FIG. 5, after the contents of the equalizer FF weight register bank 503 have been updated using ALG- 2 509 in accordance with the criterion for channel inversion, samples of the signal representing the constraint waveform are loaded into the constraint register bank 510 using an algorithm ALG- 3 511 . ALG- 3 511 refers to one of any number of algorithms that can be used to define the contents of the constraint register bank 510 . [0073] [0073]FIG. 6 depicts a detailed block diagram of ALG- 3 511 in accordance with a preferred embodiment of the present invention. An index i is formed from an overflow counter 601 that cyclically counts between 1 and N, at the symbol rate, and indexes a register bank 602 storing the N out-of-band constraint frequencies. The overflow counter 601 is comprised of a scalar fixed to the value of 1 603 , a register 604 to store the current state of the increment, an overflow test 605 to reset the value of the counter register 604 to 1 after the count exceeds the value set by a parameter N 606 which the overflow test 605 uses to conduct its comparison, and a summing node 607 to perform the incrementation of the counter register 604 . [0074] At the conclusion of the ISI-cancellation update, overflow counter 601 increments index i to access the next frequency in the frequency array 602 . The selected frequency f i is then passed to a sinusoidal generator 608 which generates samples of the complex sinusoid. [0075] Referencing FIG. 5, the samples of constraint waveform are then loaded into the constraint register bank 510 , but can also be passed first to an optional algorithm ALG- 4 512 when the constraint waveform is sinusoidal in nature to limit duty cycle as a means to reduce the computational complexity of the MF processing. The composition of ALG- 4 512 will be discussed later. [0076] Since the samples of each sinusoid are known apriori to the equalization, the constraint waveform may be loaded from ROM. Thus, an alternate embodiment of the ALG- 3 511 and ALG- 4 512 combination is a ROM lookup table. [0077] Continuing with the process flow in FIG. 5, at time t_ 2 , shortly after time t_ 1 and prior to the input of the next distorted sample to be processed, switch S 1 502 is opened and a second switch S 2 517 is closed to allow computation of a second inner product, this time between the contents of the constraint register bank 510 and the contents of the equalizer FF weight register bank 503 . Once again the bank of multiplier elements 504 and bank of summing nodes 505 are used in forming the inner product. This inner product represents a measurement of the orthogonality between the equalizer's weights and the complex constraint sinusoid residing at frequency f i at the current iteration. [0078] The sample of the previous inner product between the equalizer's weights and the constraint waveform is then passed to the 2:1 commutator 506 , which discards every other sample. Switch S 2 517 is again encountered to deliver the orthogonality inner product to the subsequent algorithms involved in the MF processing. With switch S 2 517 closed the orthogonality inner product at the output of the 2:1 decimator 506 is subtracted from a parameter β 518 , termed the constraint level, using differencing node 519 . The constraint level β 518 defines the targeted strength of the orthogonality between the equalizer's weights and the constraint waveform. The operating range for β 518 is 0≦β≦1  [4] [0079] The difference, termed the constraint error, is passed to an algorithm ALG- 5 520 that controls the rate of acquisition of the constraint update. A preferred embodiment of the present invention sets β=0 to maximize the strength of the orthogonality built between the equalizer's weights and the constraint waveform. In turn, the differencing node 519 is not necessary and so is removed. ALG- 5 520 refers to any number of algorithms that can be used to dictate the rate of acquisition of the constraint update. [0080] [0080]FIG. 7 depicts a detailed block diagram of ALG- 5 520 in accordance with a preferred embodiment of the present invention. Samples of the MF constraint error are passed to a complex conjugation operator 701 and the result is scaled by a parameter α 702 , equal to the inverse of the number of samples of the complex constraint sinusoid waveform multiplied by the amplitude of the complex constraint sinusoid, using a multiplier element 703 . When the constraint sinusoid is of unit amplitude the multiplicative parameter α 703 reduces to 1/L. The scaled MF constraint error represents an adjustment signal for the equalizer weight update associated with the MF processing. [0081] In FIG. 5 the adjustment signal formed at the output of ALG- 5 520 is then passed to switch S 2 517 . In this position, switch S 2 517 permits an update of the contents of the equalizer's FF weight register bank 503 when the adjustment signal is derived from the MF constraint error and prevents the MF constraint error adjustment signal from updating the contents of the equalizer FF weight register bank 503 when the present invention switches its mode of operation to back to the channel inversion process. [0082] With switch S 2 517 closed the adjustment signal derived from the MF constraint error is passed to an optional algorithm ALG- 6 521 to control the rate at which the contents of the equalizer weight register bank 503 are to be updated in accordance the criterion for the MF constraint. ALG- 6 521 refers to any number of algorithms that can be used to dictate the update rate of the equalizer's weights in accordance with the criterion for the constraint. [0083] [0083]FIG. 8 depicts illustrates ALG- 6 521 in accordance with a preferred embodiment of the present invention. The adjustment signal for the MF constraint update is passed to a switch S 3 801 whose open/closed state is controlled by an overflow counter 802 . The overflow counter 802 is comprised of a scalar fixed to the value of 1 803 , a register 804 to store the current state of the increment, a summing node 805 , an overflow test 806 , switches S 4 807 , S 5 808 and S 6 809 , and three parameters, P 0 810 , P 1 811 , and P 1 812 , to dictate the maximum count of the overflow counter 802 . [0084] As the joint ISI-canceling and MF adaptive equalizer initiates processing the overflow counter 802 counts at the symbol rate from 1 to the value set by parameter P 0 810 whose value is accessed by the overflow counter 802 through switch S 4 807 which, at initial conditions, is in a closed position. Through the duration of this count, switch S 3 801 is in a closed position to allow the adjustment signal derived from the MF constraint error to update the contents of the equalizer FF weight register bank 503 (ref. FIG. 5). When the incremental count in the register 804 exceeds the value specified by P 0 810 the overflow test 806 results in a binary TRUE, and switches S 3 801 and S 4 807 are opened. Switch S 4 807 is then disabled from the processing and remains in an open state throughout the remainder of the joint ISI-canceling and MF update. [0085] The increment register 804 is then set to zero and switch S 5 808 is closed to allow the overflow test 806 to use the value given by parameter P 1 811 as the new threshold of the maximum count. As the update of the joint process equalizer continues, the overflow counter 802 starts counting again from 1, but counts this time to the value given by P 1 811 . During this counting switch S 3 801 remains in an open position to keep the constraint update from updating the equalizer weights. [0086] Switch S 3 801 remains in an open position until the value in the counter register 804 exceeds the value given by P 1 811 upon which the overflow test 806 results in a binary TRUE again which prompts switch S 3 801 to close to resume updates of the contents of the equalizer's FF weight register bank 503 (ref. FIG. 5) in accordance with the MF constraint criterion. At the same time that switch S 3 801 is closed, switch S 5 808 is opened and switch S 6 809 is closed to set the maximum count of the overflow counter 806 to the value given by P 2 812 . [0087] The increment register 804 is again set to zero and as the update of the joint process equalizer continues, the overflow counter 802 starts counting again from 1 803 , but counts this time to the value given by P 2 812 . During this counting switch S 3 801 remains in a closed position until the value in the counter register 804 exceeds the value given by P 2 812 upon which the overflow test 806 results in a binary TRUE again which prompts switch S 3 801 to open to halt the update equalizer's weights. At the same time that switch S 3 801 is opened, switch S 5 808 is closed and switch S 6 809 is opened to set the maximum count of the overflow counter 802 back to the value given by P 1 811 . This process continues with the increment register 804 is again set to zero switch S 3 801 controlling constraint update rate through switches S 5 808 and S 6 809 , and parameters P 1 811 and P 2 812 . [0088] Referencing FIG. 5 again, after passing through ALG- 6 521 the adjustment signal associated with the constraint error, and derived from ALG- 5 508 , is delivered to algorithm ALG- 2 509 which performs an update of the contents of the equalizer's FF weight register bank 503 , this time in accordance with the MF constraint criterion. ALG- 2 509 refers to one of any number of algorithms that can control the adaptation of the equalizer's weights. [0089] [0089]FIG. 4 illustrates a detailed block diagram of ALG- 2 509 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0090] This completes the MF portion of the joint ISI-canceling and MF operation at the current iteration. [0091] The entire joint process equalizer update is repeated for the next iteration beginning with the elements currently residing within the data register bank 501 being shifted to the right by one position and the next sample of the distorted input waveform being loaded into the first position of the data register bank 501 . The ISI-cancellation process is initialized once again with closure of switch S 1 502 and the computation the inner product between the contents of the data register bank 501 and the contents equalizer FF weight register bank 503 . [0092] We now discuss several possible configurations for ALG-ISI-ERR 507 of FIG. 5 which generates the error sequence that drives the update of the equalizer's weights in accordance with the criterion for the cancellation of ISI. ALG-ISI-ERR 507 pertains to any state-of-the-art algorithm that can derive an error signal pertaining to the cancellation of ISI. [0093] [0093]FIG. 9 depicts a detailed block diagram of ALG-ISI-ERR 507 of FIG. 5 in accordance with a preferred embodiment of the present invention. This embodiment utilizes a training sequence 901 to form the ISI error signal. [0094] With respect to FIG. 9, after passing through the 2:1 commutator 506 (ref. FIG. 5) and switch S 1 502 (ref. FIG. 5) the equalized signal is subtracted from a known training sequence 901 , which represents samples of the distortion-less transmitted sequence at symbol rate, using a differencing node 902 . The difference signal represents the ISI error sequence and is passed to ALG- 1 508 (ref. FIG. 5) to generate the adjustment signal that directs the equalizer's weight in accordance with ISI cancellation. [0095] [0095]FIG. 10 depicts a detailed block diagram of ALG-ISI-ERR 507 of FIG. 5 in accordance with an alternate embodiment of the present invention. [0096] With respect to FIG. 10, after passing through the 2:1 commutator 506 (ref. FIG. 5) and switch S 1 502 (ref. FIG. 5) the equalized signal is passed through a slicer (decision device) 1001 which quantizes the equalized signal to the closest 2-tuple of a decision region. A differencing node 1002 subtracts the pre-quantized sample from the quantized sample to form the error sequence which is then passed onto ALG- 1 508 (FIG. 5) to generate the equalizer weight adjustment signal. This embodiment is termed the decision-directed embodiment. [0097] [0097]FIG. 11 depicts a detailed block diagram of ALG-ISI-ERR 507 of FIG. 5 in accordance with an alternate embodiment of the present invention. In this embodiment the channel inversion error is formed via the use of a statistical-based update. [0098] With respect to FIG. 11, an algorithm ALG- 7 1101 computes the value of a parameter R m measuring a ratio of statistical moments of the original modulated signal. A switch S 7 1102 is closed to deliver the value of parameter R m to a register 1103 where it will reside throughout the processing. Switch S 7 1102 is then opened. Therefore, ALG- 7 1101 executes only a single time to calculate R m and then is removed from the processing when switch S 7 1102 is opened. [0099] After passing through the 2:1 commutator 506 (ref. FIG. 5) and switch S 1 502 (ref. FIG. 5) the input sample of equalized signal is delivered to a complex conjugation device 1104 . The output of this complex conjugation device is then multiplied by the input sample of equalized signal using a multiplier device 1105 . The content of the register 1103 storing the value of parameter R m is subtracted from this product via a differencing node 1106 and this difference is then multiplied by the input sample of equalized signal via a multiplier element 1107 . This last product represents a sample of the error sequence delivered to ALG- 1 508 (ref. FIG. 5) to form the weight adjustment signal as in previous embodiments. [0100] The statistically based parameter R m is the ratio of moments of the amplitudes a j {j=1, 2, . . . , B} of the B-ary pre-pulse-shaped modulated constellation. R m =E[|a j | 2m ]/E[|a j | m ]  [3] [0101] ALG- 7 1101 refers to one of any number of algorithms that can compute the ratio of E[|a j | 2m ] to E[|a j | m ] where the operator E [x] denotes the expectation of x. [0102] [0102]FIG. 12 depicts a detailed block diagram of ALG- 7 1101 of FIG. 11 in accordance with a preferred embodiment of the present invention. The first amplitude a 1 of the set of amplitudes a j {j=1, 2, . . . , B} of the B-ary pre-pulse-shaped modulated constellation is passed through an absolute value operator 1201 to produce a value V 1 . A counter 1202 increments the value in a register 1203 from 0 to 1 with the use of a scalar 1204 set to the value of 1 and a summing node 1205 . A scalar 1206 set to the value of B and an overflow test 1207 test whether the contents in register 1203 have exceeded the value given by parameter B 1206 . [0103] V 1 is passed though a power operator 1208 which computes V 1 to the m-th power with use of parameter m 1209 . The output V 2 is then sent to two different paths of processing, an upper and lower path. In the upper path V 2 is passed through a squaring operation 1210 to form V 3 which, in turn, is delivered to the combination of a summing node 1211 and a delay register 1212 to perform an accumulation of future V 3 values. In the lower path V 2 is delivered to the combination of a summing node 1213 and delay register 1214 to perform an accumulation of future V 2 values. The entire process is repeated with input of the second 2-tuple a 2 . [0104] After all of the constellation 2-tuples have been processed the value in the increment register 1203 increments one more time. At this point, the value in the increment register 1203 exceeds the value given by parameter B 1206 and a CLOSE signal is sent to switches S 8 1215 and S 9 1216 . A division operator 1217 forms the ratio of the final values of V 2 and V 3 to form R m . [0105] [0105]FIG. 13 depicts a detailed block diagram of an alternate embodiment of the present invention. This embodiment closely resembles decision-directed embodiment with the exception that a feedback signal formed from a weighted set of previous slicer decisions adds to the equalized signal. This embodiment of the present invention is termed the decision-feedback embodiment. [0106] The process for the decision-feedback embodiment is as follows. With the output of the 2:1 commutator 506 (ref. FIG. 5) already formed and passed through switch S 1 502 (ref. FIG. 5), the contents of a decision register bank 1301 , which stores a set of the previous decisions produced from a slicer 1302 , engage the contents of a weight register bank 1303 , storing values of set of DF weights, in an inner product computation using a bank of multiplier elements 1304 and summing nodes 1305 . This inner product computation represents a sample of the DF's contribution to the total equalized signal. [0107] Next, the incoming signal to the DF embodiment is added to the DF sample using a summation node 1306 . The result of the addition represents a sample of the equalized signal and is passed to the slicer device 1302 . The equalized sample is subtracted from decision produced from the output of the slicer 1302 via a differencing node 1307 forming a sample of the ISI-cancellation error sequence. The error sample is then delivered to ALG- 1 508 (ref. FIG. 5) to form the adjustment signal needed to update the contents of the equalizer's FF weight register bank 501 (ref. FIG. 5). [0108] The sample of adjustment signal formed from ALG- 1 508 then multiplies contents of the decision register bank 1301 using a bank of multiplier elements 1308 . The resulting bank of products then adds to the current contents of the DF weight register bank 1303 using a bank of summing nodes 1309 , and the result is stored in the DF weight register bank 1303 . As an example of the DF weight update, the contents of the first (far left) register of the decision register bank 1301 , storing a set of previous decisions, multiplies the adjustment signal produced from ALG- 1 508 . The product adds to the first (far left) register position of the DF weight resister bank 1303 and the sum is stored in the first register position of the DF weight register bank 1303 . The update process continues with the next successive register positions of the DF weight register bank 1303 . [0109] At the completion of DF weight update the contents of the decision register bank 1301 are shifted to the right by one register position. The slicer 1302 output is delivered to first register position of the decision register bank 1301 . The DF operation then repeats with the inner product of the decision register bank 1301 and the DF weight register bank 1303 . [0110] With the description of the basic processing of the joint ISI-canceling and MF adaptive equalizer completed we now return to descriptions of both ALG- 4 512 and ALG- 7 522 . [0111] ALG- 4 512 performs windowing of the constraint waveform produced from ALG- 3 511 at the current equalizer iteration. When the constraint waveform is sinusoidal in nature a windowing of the sinusoidal time series weights the non-causal and causal samples furthest from the midpoint of the total duty cycle with negligible amplitude (or zero amplitude depending upon the selected window function) while emphasizing those samples nearest the duty cycle midpoint with greater importance. As a result, the samples of the windowed constraint waveform of negligible amplitude offer negligible contribution to the inner product between the equalizer FF weights and constraint waveform associated with the MF processing. Hence, the their multiply operations need not be performed and the inner product reduces to performing only the central-most multiply operations that will restore a measure of performance equivalent to that of the non-windowed constraint waveform. [0112] [0112]FIG. 14 illustrates a detailed block diagram of ALG- 4 512 in accordance with a preferred embodiment of the present invention. This embodiment performs windowing of the constraint waveform using a single window function. Samples of the constraint waveform produced from ALG- 3 511 (ref. FIG. 5) are passed to a multiplier bank 1401 which performs a point-by-point multiplication with contents of a register bank 1402 representing the window function. The resulting samples of windowed time series are then loaded into the constraint register bank 510 (ref. FIG. 5) and as the MF processing is initiated. However, in the inner product computation between the contents of the equalizer FF weight register bank 503 (ref. FIG. 5) and the contents of the constraint register bank 510 (ref. FIG. 5), only those central multiplications of the multiplier bank 504 (ref. FIG. 5) and central sums of the bank of summing nodes 505 (ref. FIG. 5) which correspond to the central samples of the windowed constraint waveform samples of non-zero or appreciable amplitudes are performed. [0113] For the singular windowing waveform various types of window functions may suffice for truncating the constraint waveform time series. For example, an unweighted window contains a steep decay in its time series which maximizes the number of extreme causal and non-causal samples of the windowed waveform that are of zero or negligible amplitude. This, in turn, minimizes the number of central-most multiplications and sums that need be performed in the inner product associated with the MF constraint. The drawback, however, is that windowing with an unweighted function maximizes the amount of spectral leakage induced from waveform time series truncation which diminishes the strength of the orthogonality between equalizer and constraint waveform. [0114] To compensate, the window function selected may contain a gradual decay of its time response such as the Hann, Hamming, Kaiser, etc. windows. For these windows, however, the number of samples of the windowed waveform, which are of zero or negligible amplitude, may not result in an appreciable workload reduction of the MF constraint processing. Hence, the window waveform is formed from a composite of multiple windows to achieved desired time series truncation with minimal spectral leakage. [0115] [0115]FIG. 15 illustrates a detailed block diagram of ALG- 4 512 in accordance with an alternate embodiment of the present invention. This embodiment performs windowing of the constraint waveform using multiple window functions. Switch S 8 1501 , initially in a closed position, allows the entire set of samples of the constraint waveform produced from ALG- 3 511 (ref. FIG. 5) to be loaded to a register bank 1502 . Switch S 8 1501 is then opened. Next, a bank of multiplier elements 1503 performs a point-by-point multiplication of the pre-windowed samples contained in register bank 1502 with samples of the first windowing function contained in a register bank 1504 . The bank of products is stored in register bank 1502 . Switch S 11 1508 remains in an open position until all windowing waveforms have been utilized. Switch S 12 1505 then moves to the windowing waveform #2 register bank 1506 . The bank of multiplier elements 1503 performs a point-by-point multiplication of the pre-windowed samples contained in register bank 1502 with samples of the second windowing function contained in register bank 1506 . The bank of products is stored in register bank 1502 . The process is repeated for all the windowing functions up to an including the last storing in windowing waveform #W register bank 1507 . Then switch S 11 1508 is closed to send the final version of the samples of windowed constraint waveform to the constraint register bank 510 (ref. FIG. 5). [0116] ALG- 7 522 is now discussed. Referencing FIG. 5, ALG- 7 522 performs an initialization of the contents of the equalizer FF weight register bank 503 with the coefficients of the RRC MF as a means to decrease the acquisition time needed to form the MF characteristics of the equalizer's composite inverse channel and MF function. [0117] [0117]FIG. 16 illustrates a detailed block diagram of ALG- 5 522 in accordance with a preferred embodiment of the present invention. Prior to the contents of the data register bank being shifted to prepare for the first sample of the distorted waveform to be loaded into the first position of the data register bank 501 (ref. FIG. 5), switch S 13 is closed to allow a coefficient set 1601 of the pre-FSE RRC MF, which spans the duration of the equalizer's FF weights, to be loaded into the register positions of the equalizer FF weight register bank 503 (ref. FIG. 5). Switch S 12 1602 is then opened to disconnect ALG- 7 522 (ref. FIG. 5) from the joint process equalizer update. [0118] [0118]FIG. 17 depicts a detailed block diagram of the joint ISI-cancelling and MF adaptive equalized partitioned as a polyphase process in accordance with a preferred embodiment of the present invention. The 2:1 decimator (ref. FIG. 5), previously at the output of the equalizer, is embedded within the fractional-spaced equalizer via the Nobel Identity. As a result, the data register bank 502 (ref. FIG. 5) is partitioned into two sub-register banks, u 0 1701 and u 1 1702 , each of which is half the length of the original non-polyphase partitioned data register bank 502 (ref. FIG. 5). In a similar manner the equalizer weight register bank 503 (ref. FIG. 5) is partitioned into sub-register banks w 0 1703 and w 1 1704 , and the constraint register bank 510 (ref. FIG. 5) is partitioned into sub-register banks c 0 1705 and c 1 1706 . [0119] The polyphase process of FIG. 17 is as follows. The elements contained within the data sub-register bank u 1 1702 are shifted to the right by one position. A sample of the distorted input waveform is then delivered to the first register position of data sub-register bank u 1 1702 via a 2:1 commutation device COM_ 1 1707 . [0120] At time t_ 1 , a switch S 1 1708 is closed to allow the contents of the data sub-register bank u 1 1702 to engage the contents of equalizer FF weight sub-register bank w 1 1704 , storing half of the equalizer's weights, the odd indexed weights (or even indexed weights depending upon polyphase methodology), in an inner product computation using a bank of multiplier elements 1709 and a bank of summation nodes 1710 . [0121] In this embodiment, the polyphase configuration of the present invention, the number of multiplier elements in the multiplier bank 1709 and number of summing nodes in the bank of summing nodes 1710 are both approximately half that of each of the non-polyphase configuration. The inner product computation represents half the total equalized decimated result at the current iteration, and with switch S 1 1708 closed the inner product is stored in a single delay element 1711 for future use. Switch S 14 1712 , currently in an open position, prevents the error sample associated with ISI cancellation from being formed until the second half of the total equalized decimated signal is computed. [0122] Next, samples of the signal representing the constraint waveform are loaded into constraint sub-register banks c 0 1705 and c 1 1706 using algorithm ALG- 3 1728 , but as in the non-polyphase embodiment, can also be passed first to an optional algorithm ALG- 4 1729 when the constraint waveform is sinusoidal in nature to limit duty cycle as a means to reduce the computational complexity of the MF processing. FIG. 6 illustrates a detailed block diagram of ALG- 3 1728 in accordance with a preferred embodiment of the present invention as previously described and discussed. FIGS. 14 - 15 illustrate detailed block diagrams of ALG- 4 1729 in accordance with preferred embodiments of the present invention as previously described and discussed. [0123] At time t_ 2 , shortly after time t_ 1 and prior to the input of the next distorted sample to be processed, switch S 1 1708 is opened and a second switch S 2 1713 is closed to allow computation of a second inner product, this time between the contents of the constraint sub-register bank c 1 1706 and the contents of the equalizer FF weight sub-register bank w 1 1704 . Again the bank of multiplier elements 1709 and bank of summing nodes 1710 are used in forming this inner product. This second inner product represents the first half the total contribution to the sample measuring the orthogonality between the equalizer's FF weights and the constraint waveform at the current iteration. With switch S 2 1713 closed it is stored in a single delay element 1714 for future use. Switch S 15 1715 , currently in an open position, prevents the MF constraint error from being formed until the second half of the total contribution to the measure of orthogonality between the equalizer's FF weights and the constraint waveform is formed. Switch S 2 1713 is then opened. [0124] Next, commutator COM 1 1707 moves to the data sub-register bank u 0 1702 , and a new sample of the distorted waveform is input to the first register position of data sub-register bank u 1 1702 . A second commutator COM 2 1716 moves to data sub-register bank u 0 1701 and constraint sub-register bank c 0 1705 , while a third commutator COM 3 1717 moves to the equalizer FF sub-register bank w 0 1703 , with all commutator movements controlled by a clock 1718 . [0125] The elements contained within the data sub-register bank u 0 1701 are then shifted to the right by one position and the next sample of the distorted input waveform is then delivered to the first register position of data sub-register bank u 0 1701 via the commutation device COM_ 1 1707 . [0126] At time t_ 3 , shortly after the input of the next distorted sample to data sub-register u 0 1701 , switch S 1 1708 is closed to allow the contents of the data sub-register bank u 0 1701 to engage the contents of equalizer FF weight sub-register bank w 0 1703 in a third inner product computation using the bank of multiplier elements 1709 and bank of summing nodes 1710 . With switch S 1 1708 closed this third inner product is added to the first inner product currently stored in the delay register 1711 via a summing node 1719 to form a sum Ps 1 . Ps 1 represents a sample of the equalized signal at the current iteration. Next, switch S 14 1712 , is closed to send sum Ps 1 to ALG-ISI-ERR 1720 to form the error associated with ISI-cancellation. FIGS. 9 - 11 illustrate detailed block diagrams of ALG-ISI-ERR 1720 in accordance with preferred embodiments of the present invention as previously described and discussed. [0127] The error is then sent to ALG- 1 1721 to form the adjustment signal needed to update the equalizer's FF weights in accordance with the criterion for ISI cancellation. FIG. 3 illustrates a detailed block diagram of ALG- 1 1721 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0128] Continuing with the process description of FIG. 17 the adjustment signal formed at the output of ALG- 1 1721 is then passed to switch S 1 1708 . In this position, switch S 1 1708 permits an update of the contents of the equalizer's FF weights when the adjustment signal is derived from the channel inversion error and prevents the channel inversion error adjustment signal from updating the FF weights when the present invention switches its mode of operation to the MF processing. With switch S 1 1708 in a closed position, the adjustment signal derived from ALG- 1 1721 is delivered to algorithm ALG- 2 1722 which performs an update of the contents of the equalizer FF weight sub-register banks w 0 1703 and an update of the contents in equalizer FF weight sub-register banks w 1 1704 . FIG. 4 illustrates a detailed block diagram of ALG- 2 1722 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0129] This completes the weight update associated with the ISI-cancellation process at the current iteration for polyphase embodiment of the present invention. [0130] At time t_ 4 , shortly after time t_ 3 and prior to the input of the next distorted sample to be processed, switch S 1 1708 is opened and switch S 2 1713 is closed to allow computation of an inner product, the fourth inner product in the series, between the contents of the constraint sub-register bank c 0 1705 and the contents of the equalizer FF weight sub-register bank w 0 1703 using the bank of multiplier elements 1709 and the bank of summing nodes 1710 servicing the computation. With switch S 2 1713 closed the fourth inner product is added to the second inner product currently stored in the delay register 1714 via a summing node 1723 to form a sum Ps 2 . Ps 2 represents a sample of the total measure of orthogonality between the equalizer's FF weights and constraint waveform at the current iteration. [0131] Next, switch S 15 1715 is closed to send sum Ps 2 onto the processing that derives the constraint error. Ps 2 is subtracted from the constraint level parameter β 1724 using differencing node 1725 as in the previous embodiments. The difference, termed the constraint error, is passed to an algorithm ALG- 5 1726 , as in prior embodiments, to form the adjustment signal needed to update the contents of both equalizer FF weight sub-register banks, w 0 1703 and W 1 1704 , in accordance with the MF constraint criterion. [0132] With switch S 2 1713 closed the adjustment signal derived from the MF constraint error is passed to algorithm optional ALG- 6 1727 to control the rate at which the contents of equalizer FF weight sub-register banks w 0 1703 and w 1 1704 are to be updated in accordance with the MF constraint criterion. FIG. 8 illustrates a detailed block diagram of ALG- 6 1722 in accordance with a preferred embodiment of the present invention as previously described and discussed. [0133] Continuing with the process description of FIG. 17, after passing through ALG- 6 1727 the adjustment signal associated with the constraint error, and derived from ALG- 5 1726 , is delivered to algorithm ALG- 2 1722 , as in previous embodiments, which performs an update of the contents of the both the equalizer FF weight sub-register banks w 0 1703 and w 1 1704 in accordance with the MF constraint criterion. Switch S 15 1715 is then opened. [0134] This completes the MF portion of the joint ISI-cancelling and MF operation at the current iteration for the polyphase embodiment of the present invention. [0135] Commutator COM_ 1 1707 then moves back to the u 1 register bank 1702 , COM_ 2 1716 moves back to data sub-register bank u 1 1702 and constraint sub-register bank c 1 1706 , and COM_ 3 1717 moves back to the equalizer FF weight sub-register bank w 1 1704 , all movements again controlled by the clock 1718 . Also the contents of delay register 1711 and delay register 1714 are zeroed out. [0136] The entire process is repeated with the contents equalizer data sub-register bank u 1 1702 shifted to the right by one position to prepare for the next sample of distorted input waveform to be delivered to the first register position of u 1 1702 . [0137] With respect to the configuration of ALG-ISI-ERR 1720 in the polyphase embodiment, FIGS. 9 - 11 illustrate detailed block diagrams of ALG-ISI-ERR 1720 in accordance with preferred embodiments of the present invention as previously described and discussed. [0138] When ALG-ISI-ERR 1720 in the polyphase embodiment is defined as in FIG. 10, where a slicer forms the equalization error, a DF configuration can be used to enhance the cancellation of ISI. FIG. 12 illustrates a detailed block diagram of the DF configuration in accordance with a preferred embodiment of the present invention as previously described and discussed. [0139] The polyphase embodiment of the present invention also benefits from initialization of the equalizer's FF weights using ALG- 7 1730 . FIG. 15 illustrates a detailed block diagram of ALG- 7 1730 in accordance with a preferred embodiment of the present invention. Since the constraint register bank 510 (ref. FIG. 15) is partitioned into sub-register banks c 0 1705 and c 1 1706 in the polyphase embodiment, ALG- 7 1730 initializes sub-register banks c 0 1705 and c 1 1706 with the odd and even indexed RRC MF taps, respectively, or vice versa. [0140] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

There is disclosed a fractional-spaced equalizer (FSE) that is capable of performing joint intersymbol-interference (ISI) cancellation and matched filter (MF) processing. The FSE employs a constrained optimization technique to control the out-of-band frequency response of the equalizer's FIR while, at the same time, controlling the pass-band and roll-off of the FIR to cancel ISI. The format of the constrained optimization technique permits a single bank of multipliers elements to service the inner product computations associated both with the ISI cancellation and MF operations. This time-multiplexing technique promotes a conservation of hardware associated with the MF, and provides for a reduction in the computational complexity leading to an increase in power efficiency.

FIELD OF THE INVENTION [0001] The present invention relates to irrigation sprinklers and more particularly to sprinklers, which are driven for rotation about a vertical axis by an output water stream which impacts on a sprinkler element. BACKGROUND OF THE INVENTION [0002] Various types of impact sprinklers are known in the art. SUMMARY OF THE INVENTION [0003] The present invention seeks to provide an improved irrigation sprinkler. [0004] There is thus provided in accordance with a preferred embodiment of the present invention an irrigation sprinkler including a base defining an axis, a pressurized water inlet mounted onto the base, a nozzle, communicating with the inlet, and providing a pressurized water stream which is generally outwardly directed relative to the axis and a water stream deflector for engaging the pressurized water stream from the nozzle and deflecting at least part of the water stream generally azimuthally with respect to the axis, the water stream deflector including a first pressurized water stream engagement surface and a second pressurized water stream engagement surface downstream of the first pressurized water stream engagement surface, the first pressurized water stream engagement surface having a pressurized water stream directing configuration arranged to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface, which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface and to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface, which at least a second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface. [0005] Preferably, the nozzle is selectable to provide a selectable water stream quantity which may be less than, equal to or greater than the predetermined water stream quantity. [0006] In accordance with a preferred embodiment of the present invention, the pressurized water stream directing configuration of the first pressurized water stream engagement surface includes at least one vane which divides the pressurized water stream into the first portion of the pressurized water stream and the at least a second portion of the pressurized water stream. Additionally, the at least one vane includes a plurality of vanes, which divide the pressurized water stream into the first portion of the pressurized water stream and a plurality of second portions of the pressurized water stream. Alternatively or alternatively, the at least one vane has a generally triangular cross section. [0007] Preferably, the second pressurized water stream engagement surface has at least one water stream bypass aperture formed therein and the first pressurized water stream engagement surface is arranged to direct the at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface through the at least one water stream bypass aperture. [0008] In accordance with a preferred embodiment of the present invention, the second pressurized water stream engagement surface is configured to be impinged upon generally only by the first portion of the pressurized water stream and the first pressurized water stream engagement surface is arranged to direct the at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface away from the second pressurized water stream engagement surface. [0009] Preferably, the pressurized water stream directing configuration of the first pressurized water stream engagement surface includes at least one channel through which passes the pressurized water stream. In accordance with a preferred embodiment of the present invention, the at least one channel includes a pair of vanes which are joined by an integrally formed top plate. Additionally or alternatively, the at least one channel has an at least partially curved cross section. In accordance with a preferred embodiment of the present invention, the at least one channel has a generally triangular cross section. [0010] In accordance with a preferred embodiment of the present invention, the first pressurized water stream engagement surface includes at least one vane which divides the pressurized water stream into the first portion of the pressurized water stream and the at least a second portion of the pressurized water stream, the second pressurized water stream engagement surface has at least one water stream bypass aperture formed therein by at least one vane, the first pressurized water stream engagement surface is arranged to direct the at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface through the at least one water stream bypass aperture and the at least one vane which defines the at least one water stream bypass aperture and the at least one vane which divides the pressurized water stream on the first pressurized water stream engagement surface are formed as generally collinear continuations of each other. [0011] Preferably, the irrigation sprinkler also includes at least one intermediate vane spanning both the first and the second pressurized water stream engagement surfaces and joining the at least one vane which define the at least one water stream bypass aperture and the at least one vane which divides the pressurized water stream on the first pressurized water stream engagement surface. [0012] In accordance with a preferred embodiment of the present invention, the second pressurized water stream engagement surface downstream of the first pressurized water stream engagement surface is curved. Preferably, the first pressurized water stream engagement surface is generally planar and the second pressurized water stream engagement surface downstream of the first pressurized water stream engagement surface is curved. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: [0014] FIGS. 1A , 1 B, 1 C and 1 D are simplified isometric illustrations, taken from four different viewpoints, of an assembled sprinkler constructed and operative in accordance with a preferred embodiment of the present invention; [0015] FIGS. 2A and 2B are simplified exploded view illustrations, taken from two different viewpoints, of the sprinkler of FIGS. 1A-1D ; [0016] FIGS. 3A and 3B are simplified side view illustrations of a hammer element forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 3A & 3B being mutually rotated by 180 degrees; [0017] FIGS. 3C and 3D are simplified isometric illustrations of the hammer element of FIGS. 3A and 3B , taken from two different viewpoints; [0018] FIGS. 3E , 3 F and 3 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 3A ; [0019] FIGS. 3H , 3 I, 3 J and 3 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 3A ; [0020] FIGS. 4A and 4B are simplified side view illustrations of an alternative hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 4A & 4B being mutually rotated by 180 degrees; [0021] FIGS. 4C and 4D are simplified isometric illustrations of the hammer element of FIGS. 4A and 4B , taken from two different viewpoints; [0022] FIGS. 4E , 4 F and 4 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 4A ; [0023] FIGS. 4H , 4 I, 4 J and 4 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 4A ; [0024] FIGS. 5A and 5B are simplified side view illustrations of a further alternative hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 5A & 5B being mutually rotated by 180 degrees; [0025] FIGS. 5C and 5D are simplified isometric illustrations of the hammer element of FIGS. 5A and 5B , taken from two different viewpoints; [0026] FIGS. 5E , 5 F and 5 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 5A ; [0027] FIGS. 5H , 5 I, 5 J and 5 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 5A ; [0028] FIGS. 6A and 6B are simplified side view illustrations of another hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 6A & 6B being mutually rotated by 180 degrees; [0029] FIGS. 6C and 6D are simplified isometric illustrations of the hammer element of FIGS. 6A and 6B , taken from two different viewpoints; [0030] FIGS. 6E , 6 F and 6 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 6A ; [0031] FIGS. 6H , 6 I, 6 J and 6 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 6A ; [0032] FIGS. 7A and 7B are simplified side view illustrations of yet another hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 7A & 7B being mutually rotated by 180 degrees; [0033] FIGS. 7C and 7D are simplified isometric illustrations of the hammer element of FIGS. 7A and 7B , taken from two different viewpoints; [0034] FIGS. 7E , 7 F and 7 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 7A ; [0035] FIGS. 7H , 7 I, 7 J and 7 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 7A ; [0036] FIGS. 8A and 8B are simplified side view illustrations of still another hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 8A & 8B being mutually rotated by 180 degrees; [0037] FIGS. 8C and 8D are simplified isometric illustrations of the hammer element of FIGS. 8A and 8B , taken from two different viewpoints; [0038] FIGS. 8E , 8 F and 8 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 8A ; [0039] FIGS. 8H , 8 I, 8 J and 8 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 8A ; [0040] FIGS. 9A and 9B are simplified side view illustrations of still another hammer element suitable for forming part of the sprinkler of FIGS. 1A-1D , 2 A & 2 B, FIGS. 9A & 9B being mutually rotated by 180 degrees; [0041] FIGS. 9C and 9D are simplified isometric illustrations of the hammer element of FIGS. 9A and 9B , taken from two different viewpoints; [0042] FIGS. 9E , 9 F and 9 G are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 9A ; [0043] FIGS. 9H , 9 I, 9 J and 9 K are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 9A ; [0044] FIGS. 10A , 10 B & 10 C are respective simplified front view, top view and back view illustrations of the sprinkler of FIGS. 1A-3B , showing water flows therethrough when a relatively small nozzle is employed; [0045] FIG. 10D is a simplified sectional illustration taken along lines D-D in FIG. 10A ; [0046] FIGS. 11A , 11 B & 11 C are respective simplified front view, top view and back view illustrations of the sprinkler of FIGS. 1A-3B , showing water flows therethrough when a relatively small nozzle is employed; [0047] FIG. 11D is a simplified sectional illustration taken along lines D-D in FIG. 11A ; and [0048] FIG. 11E is a simplified sectional illustration taken along lines E-E in FIG. 11A . DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0049] Reference is made to FIGS. 1A , 1 B, 1 C and 1 D, which are simplified isometric illustrations, taken from four different viewpoints, of an assembled sprinkler constructed and operative in accordance with a preferred embodiment of the present invention, and to FIGS. 2A and 2B , which are simplified exploded view illustrations, taken from two different viewpoints, of the sprinkler of FIGS. 1A-1D . [0050] As seen in FIGS. 1A-2B , the sprinkler comprises a sprinkler body 102 including a riser portion 104 , a forward nozzle mounting portion 106 , a rearward nozzle mounting portion 108 and a bridge portion 110 . [0051] Riser portion 104 preferably includes a generally hollow cylindrical portion 112 , a top flange portion 114 and a bottom threaded portion 116 . [0052] Forward nozzle mounting portion 106 preferably includes a radially extending and upwardly extending generally hollow cylindrical portion 122 , which communicates with the interior of generally hollow cylindrical portion 112 , and a pair of nozzle mounting protrusions 124 on an upwardly and radially outward edge of cylindrical portion 122 . [0053] Rearward nozzle mounting portion 108 preferably includes a radially extending and upwardly extending generally hollow cylindrical portion 132 , which communicates with the interior of generally hollow cylindrical portion 112 , and a pair of nozzle mounting protrusions 134 on an upwardly and radially outward edge of cylindrical portion 132 . [0054] Bridge portion 110 preferably includes a pair of upwardly extending arms 142 and 144 , which support a joining portion 146 defining a flange 148 having a central aperture 150 which is spaced from a corresponding recess 152 along a vertical axis 154 . Underlying flange 148 there are provided a plurality of, typically four, spring mounting protrusions 156 . [0055] As seen most clearly in FIGS. 2A & 2B , mounted on riser portion 104 are multiple elements, which are here described in physical descending order from the element which lies below and against top flange portion 114 . A sand protection sleeve 162 encloses a compressed thrust spring 164 . A thrust spring seat 166 underlies spring 164 and overlies and partially surrounds a top flange 168 of a threaded connector base 170 . Connector base 170 is formed with an outer threaded bottom portion 172 , which serves for mounting of the entire sprinkler. A plurality of washers, typically including a two rubber washers 174 and 176 and an intermediate low friction washer 178 , are retained about riser cylindrical portion 112 by an apertured retaining cap 180 , which is threaded onto bottom threaded portion 116 of riser 104 . [0056] A selectable size forward nozzle 190 is replaceably mounted onto forward nozzle mounting portion 106 and retained thereon by engagement with nozzle mounting protrusions 124 . [0057] A selectable size rearward nozzle 192 is replaceably mounted onto rearward nozzle mounting portion 108 and is retained thereon by engagement with nozzle mounting protrusions 134 . Alternatively a plug (not shown) may replace the selectable rearward nozzle 192 . [0058] A vertical hammer mounting shaft 196 is preferably mounted along vertical axis 154 and extends through aperture 150 and is seated in recess 152 . Disposed about shaft 196 is a hammer sand protection sleeve 198 and a drive spring 200 , which is mounted at one end thereon onto four spring mounting protrusions 156 . [0059] A hammer 210 is rotatably mounted onto shaft 196 . Various embodiments of hammers are described hereinbelow in detail. A spray diffuser 212 may optionally be mounted on hammer 210 . [0060] Reference is now made to FIGS. 3A and 3B , which are simplified side view illustrations of a hammer element 300 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 3A & 3B being mutually rotated by 180 degrees, and to FIGS. 3C and 3D , which are simplified isometric illustrations of the hammer element of FIGS. 3A and 3B , taken from two different viewpoints. Reference is also made to FIGS. 3E , 3 F and 3 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 3A , and to FIGS. 3H , 3 I, 3 J and 3 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 3A . [0061] As seen in FIGS. 3A-3K , hammer 300 preferably includes a generally central hub portion 302 that defines a cylindrical sleeve portion 304 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 302 also preferably defines a plurality of, typically four, spring mounting protrusions 306 . [0062] Extending generally forwardly from hub portion 302 is a deflector mounting arm 308 from which extends a deflector 310 . Deflector mounting arm 308 also preferably includes an attachment recess 312 and aperture 314 for optional mounting thereon of spray diffuser 212 . [0063] Extending generally rearwardly from hub portion 302 is a balancing arm 316 . [0064] Reference is now particularly made to deflector 310 and to FIGS. 3E-3K . It is a particular feature of the present invention that deflector 310 includes a first pressurized water stream engagement surface 320 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 322 , downstream of the first pressurized water stream engagement surface 320 , wherein the first pressurized water stream engagement surface 320 has a pressurized water stream channeling configuration arranged: [0065] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 320 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 322 , and [0066] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 320 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 322 . [0067] Preferably, the second pressurized water stream engagement surface 322 has at least one, and typically two, water stream bypass apertures 324 formed therein and the first pressurized water stream engagement surface 320 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 320 through the water stream bypass aperture or apertures 324 . [0068] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 320 is preferably formed with two mutually spaced generally parallel upstanding vanes 330 , having parallel mutually facing surfaces and non parallel opposite surfaces, which divide surface 320 into preferably three water engagement sub-surfaces 332 , 334 and 336 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 332 , 334 and 336 is generally identical, however, alternatively, the individual sub-surfaces 332 , 334 and 336 may have different widths. Alternatively, the number of vanes 330 provided may be more or less than two. [0069] Preferably vanes 330 have a generally truncated triangular cross section and have increased thickness from a stream incoming edge 340 of first pressurized water stream engagement surface 320 to a stream exiting edge 342 of the first pressurized water stream engagement surface 320 . Preferably vanes 330 each have a tapered stream facing edge 344 . [0070] First water stream engagement surface 320 is preferably generally flat except for a short tapered portion adjacent incoming edge 340 . [0071] Both the first and second water stream engagement surfaces 320 and 322 are defined by side walls 350 and 352 , which join first and second water stream engagement surfaces 320 and 322 and define an open space therebetween. [0072] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 322 is preferably formed with two mutually spaced generally parallel upstanding vanes 360 which divide surface 322 into preferably three water engagement sub-surfaces 362 , 364 and 366 . [0073] In the illustrated embodiment, the width of each of water engagement sub-surfaces 362 , 364 and 366 is generally identical, however, alternatively, the individual sub-surfaces 362 , 364 and 366 may have different widths. Alternatively, the number of vanes 360 provided may be more or less than two. [0074] Preferably vanes 360 have a generally uniform thickness from a stream incoming edge 370 of second pressurized water stream engagement surface 322 to a stream exiting edge 372 of the second pressurized water stream engagement surface 322 . Preferably vanes 360 each have a tapered stream facing edge 374 . [0075] Second water stream engagement surface 322 is preferably generally curved, faces generally oppositely to first water stream engagement surface 320 and includes a generally flat portion 376 adjacent incoming edge 370 , which extends into a generally curved portion 378 , adjacent stream exiting edge 372 . [0076] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 362 and 366 , on opposite sides of water engagement sub-surface 364 , are formed with apertures extending nearly all along generally curved portion 378 and preferably along a downstream part of flat portion 376 . [0077] Reference is now made to FIGS. 4A and 4B , which are simplified side view illustrations of a hammer element 400 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 4A & 4B being mutually rotated by 180 degrees, and to FIGS. 4C and 4D , which are simplified isometric illustrations of the hammer element of FIGS. 4A and 4B , taken from two different viewpoints. Reference is also made to FIGS. 4E , 4 F and 4 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 4A , and to FIGS. 4H , 4 I, 4 J and 4 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 4A . [0078] As seen in FIGS. 4A-4K , hammer 400 preferably includes a generally central hub portion 402 that defines a cylindrical sleeve portion 404 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 402 also preferably defines a plurality of, typically four, spring mounting protrusions 406 . [0079] Extending generally forwardly from hub portion 402 is a deflector mounting arm 408 from which extends a deflector 410 . Deflector mounting arm 408 also preferably includes an attachment recess 412 and aperture 414 for optional mounting thereon of spray diffuser 212 . [0080] Extending generally rearwardly from hub portion 402 is a balancing arm 416 . [0081] Reference is now particularly made to deflector 410 and to FIGS. 4E-4K . It is a particular feature of the present invention that deflector 410 includes a first pressurized water stream engagement surface 420 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 422 , downstream of the first pressurized water stream engagement surface 420 , wherein the first pressurized water stream engagement surface 420 has a pressurized water stream channeling configuration arranged: [0082] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream 420 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 422 , and [0083] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 420 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 422 . [0084] Preferably, the second pressurized water stream engagement surface 422 has at least one, and typically two, water stream bypass apertures 424 formed therein and the first pressurized water stream engagement surface 420 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 420 through the water stream bypass aperture or apertures 424 . [0085] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 420 is preferably formed with two mutually spaced generally parallel upstanding vanes 430 , having parallel mutually facing surfaces and non parallel opposite surfaces, which divide surface 420 into preferably three water engagement sub-surfaces 432 , 434 and 436 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 432 , 434 and 436 is generally identical, however, alternatively, the individual sub-surfaces 432 , 434 and 436 may have different widths. Alternatively, the number of vanes 430 provided may be more or less than two. [0086] Preferably vanes 430 have a generally truncated triangular cross section and have increased thickness from a stream incoming edge 440 of first pressurized water stream engagement surface 420 to a stream exiting edge 442 of the first pressurized water stream engagement surface 420 . Preferably vanes 430 each have a tapered stream facing edge 444 . [0087] First water stream engagement surface 420 is preferably generally flat except for a short tapered portion adjacent incoming edge 440 . [0088] Both the first and second water stream engagement surfaces 420 and 422 are defined by side walls 450 and 452 , which join first and second water stream engagement surfaces 420 and 422 and define an open space therebetween. [0089] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 422 is preferably formed with two mutually spaced generally parallel upstanding vanes 460 which divide surface 422 into preferably three water engagement sub-surfaces 462 , 464 and 466 . [0090] In the illustrated embodiment, the width of each of water engagement sub-surfaces 462 , 464 and 466 is generally identical, however, alternatively, the individual sub-surfaces 462 , 464 and 466 may have different widths. Alternatively, the number of vanes 460 provided may be more or less than two. [0091] Preferably vanes 460 have a generally uniform thickness therealong from a stream incoming edge 470 of second pressurized water stream engagement surface 422 . Preferably vanes 460 each have a tapered stream facing edge 471 . [0092] Second water stream engagement surface 422 is preferably generally curved, faces generally oppositely to first water stream engagement surface 420 and includes a generally flat portion 472 adjacent incoming edge 470 . Only water engagement sub-surface 464 extends into a generally curved portion 474 . [0093] Thus it is appreciated that, as distinct from the embodiment described hereinabove with reference to FIGS. 3A-3K , in the embodiment of FIGS. 4A-4K , the water engagement sub-surfaces 462 and 466 have respective stream exiting edges 476 and 478 , which are relatively close to and downstream of stream incoming edge 470 and water engagement sub-surface 464 has a stream exiting edge 480 which is much further downstream thereof. [0094] Reference is now made to FIGS. 5A and 5B , which are simplified side view illustrations of a hammer element 500 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 5A & 5B being mutually rotated by 180 degrees, and to FIGS. 5C and 5D , which are simplified isometric illustrations of the hammer element of FIGS. 5A and 5B , taken from two different viewpoints. Reference is also made to FIGS. 5E , 5 F and 5 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 5A , and to FIGS. 5H , 5 I, 5 J and 5 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 5A . [0095] As seen in FIGS. 5A-5K , hammer 500 preferably includes a generally central hub portion 502 that defines a cylindrical sleeve portion 504 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 502 also preferably defines a plurality of, typically four, spring mounting protrusions 506 . [0096] Extending generally forwardly from hub portion 502 is a deflector mounting arm 508 from which extends a deflector 510 . Deflector mounting arm 508 also preferably includes an attachment recess 512 and aperture 514 for optional mounting thereon of spray diffuser 212 . [0097] Extending generally rearwardly from hub portion 502 is a balancing arm 516 . [0098] Reference is now particularly made to deflector 510 and to FIGS. 5E-5K . It is a particular feature of the present invention that deflector 510 includes a first pressurized water stream engagement surface 520 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 522 , downstream of the first pressurized water stream engagement surface 520 , wherein the first pressurized water stream engagement surface 520 has a pressurized water stream channeling configuration arranged: [0099] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 520 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 522 , and [0100] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 520 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 522 . [0101] Preferably, the second pressurized water stream engagement surface 522 has at least one, and typically two, water stream bypass apertures 524 formed therein and the first pressurized water stream engagement surface 520 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 520 through the water stream bypass aperture or apertures 524 . [0102] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 520 is preferably formed with two mutually spaced generally parallel upstanding vanes 530 , having parallel mutually facing surfaces and non parallel opposite surfaces, which divide surface 520 into preferably three water engagement sub-surfaces 532 , 534 and 536 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 532 , 534 and 536 is generally identical, however, alternatively, the individual sub-surfaces 532 , 534 and 536 may have different widths. Alternatively, the number of vanes 530 provided may be more or less than two. [0103] Preferably vanes 530 have a generally triangular cross section and have increased thickness from a stream incoming edge 540 of first pressurized water stream engagement surface 520 to a stream exiting edge 542 of the first pressurized water stream engagement surface 520 . Preferably vanes 530 each have a tapered stream facing edge 544 . [0104] First water stream engagement surface 520 is preferably generally flat except for a short tapered portion adjacent incoming edge 540 . [0105] Both the first and second water stream engagement surfaces 520 and 522 are defined by side walls 550 and 552 , which join first and second water stream engagement surfaces 520 and 522 and define an open space therebetween. [0106] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 522 is preferably formed with two mutually spaced generally parallel upstanding vanes 560 which divide surface 522 into preferably three water engagement sub-surfaces 562 , 564 and 566 . [0107] In the illustrated embodiment, the width of each of water engagement sub-surfaces 562 , 564 and 566 is generally identical, however, alternatively, the individual sub-surfaces 562 , 564 and 566 may have different widths. Alternatively, the number of vanes 560 provided may be more or less than two. [0108] Preferably vanes 560 have a generally uniform thickness from a stream incoming edge 570 of second pressurized water stream engagement surface 522 to a stream exiting edge 572 of the second pressurized water stream engagement surface 522 . Preferably vanes 560 each have a tapered stream facing edge 574 . [0109] Second water stream engagement surface 522 is preferably generally curved, faces generally oppositely to first water stream engagement surface 520 and includes a generally flat portion 576 adjacent incoming edge 570 , which extends into a generally curved portion 578 , adjacent stream exiting edge 572 . [0110] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 562 and 566 , on opposite sides of water engagement sub-surface 564 , are formed with apertures extending nearly all along generally curved portion 578 and preferably along a downstream part of flat portion 576 . [0111] Reference is now made to FIGS. 6A and 6B , which are simplified side view illustrations of a hammer element 600 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 6A & 6B being mutually rotated by 180 degrees, and to FIGS. 6C and 6D , which are simplified isometric illustrations of the hammer element of FIGS. 6A and 6B , taken from two different viewpoints. Reference is also made to FIGS. 6E , 6 F and 6 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 6A , and to FIGS. 6H , 6 I, 6 J and 6 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 6A . [0112] As seen in FIGS. 6A-6K , hammer 600 preferably includes a generally central hub portion 602 that defines a cylindrical sleeve portion 604 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 602 also preferably defines a plurality of, typically four, spring mounting protrusions 606 . [0113] Extending generally forwardly from hub portion 602 is a deflector mounting arm 608 from which extends a deflector 610 . Deflector mounting arm 608 also preferably includes an attachment recess 612 and aperture 614 for optional mounting thereon of spray diffuser 212 . [0114] Extending generally rearwardly from hub portion 602 is a balancing arm 616 . [0115] Reference is now particularly made to deflector 610 and to FIGS. 6E-6K . It is a particular feature of the present invention that deflector 610 includes a first pressurized water stream engagement surface 620 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 622 , downstream of the first pressurized water stream engagement surface 620 , wherein the first pressurized water stream engagement surface 620 has a pressurized water stream channeling configuration arranged: [0116] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 620 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 622 , and [0117] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 620 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 622 . [0118] Preferably, the second pressurized water stream engagement surface 622 has at least one, and typically two, water stream bypass apertures 624 formed therein and the first pressurized water stream engagement surface 620 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 620 through the water stream bypass aperture or apertures 624 . [0119] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 620 is preferably formed with two mutually spaced generally parallel upstanding vanes 630 , having parallel mutually facing surfaces and non parallel opposite surfaces, which divide surface 620 into preferably three water engagement sub-surfaces 632 , 634 and 636 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 632 , 634 and 636 is generally identical, however, alternatively, the individual sub-surfaces 632 , 634 and 636 may have different widths. Alternatively, the number of vanes 630 provided may be more or less than two. In this embodiment, vanes 630 are joined by an integrally formed top plate 638 , thereby defining a water flow channel 639 between vanes 630 and top plate 638 . [0120] Preferably vanes 630 have a generally truncated triangular cross section and have increased thickness from a stream incoming edge 640 of first pressurized water stream engagement surface 620 to a stream exiting edge 642 of the first pressurized water stream engagement surface 620 . Preferably vanes 630 each have a tapered stream facing edge 644 . [0121] First water stream engagement surface 620 is preferably generally flat except for a short tapered portion adjacent incoming edge 640 . [0122] Both the first and second water stream engagement surfaces 620 and 622 are defined by side walls 650 and 652 , which join first and second water stream engagement surfaces 620 and 622 and define an open space therebetween. [0123] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 622 is preferably formed with two mutually spaced generally parallel upstanding vanes 660 which divide surface 622 into preferably three water engagement sub-surfaces 662 , 664 and 666 . [0124] In the illustrated embodiment, the width of each of water engagement sub-surfaces 662 , 664 and 666 is generally identical, however, alternatively, the individual sub-surfaces 662 , 664 and 666 may have different widths. Alternatively, the number of vanes 660 provided may be more or less than two. [0125] Preferably vanes 660 have a generally uniform thickness from a stream incoming edge 670 of second pressurized water stream engagement surface 622 to a stream exiting edge 672 of the second pressurized water stream engagement surface 622 . Preferably vanes 660 each have a tapered stream facing edge 674 . [0126] Second water stream engagement surface 622 is preferably generally curved, faces generally oppositely to first water stream engagement surface 620 and includes a generally flat portion 676 adjacent incoming edge 670 , which extend into a generally curved portion 678 , adjacent stream exiting edge 672 . [0127] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 662 and 666 , on opposite sides of water engagement sub-surface 664 , are formed with apertures extending nearly all along generally curved portion 678 and preferably along a downstream part of flat portion 676 . [0128] Reference is now made to FIGS. 7A and 7B , which are simplified side view illustrations of a hammer element 700 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 7A & 7B being mutually rotated by 180 degrees, and to FIGS. 7C and 7D , which are simplified isometric illustrations of the hammer element of FIGS. 7A and 7B , taken from two different viewpoints. Reference is also made to FIGS. 7E , 7 F and 7 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 7A , and to FIGS. 7H , 7 I, 7 J and 7 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 7A . [0129] As seen in FIGS. 7A-7K , hammer 700 preferably includes a generally central hub portion 702 that defines a cylindrical sleeve portion 704 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 702 also preferably defines a plurality of, typically four, spring mounting protrusions 706 . [0130] Extending generally forwardly from hub portion 702 is a deflector mounting arm 708 from which extends a deflector 710 . Deflector mounting arm 708 also preferably includes an attachment recess 712 and aperture 714 for optional mounting thereon of spray diffuser 212 . [0131] Extending generally rearwardly from hub portion 702 is a balancing arm 716 . [0132] Reference is now particularly made to deflector 710 and to FIGS. 7E-7K . It is a particular feature of the present invention that deflector 710 includes a first pressurized water stream engagement surface 720 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 722 , downstream of the first pressurized water stream engagement surface 720 , wherein the first pressurized water stream engagement surface 720 has a pressurized water stream channeling configuration arranged: [0133] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 720 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 722 , and [0134] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 720 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 722 . [0135] Preferably, the second pressurized water stream engagement surface 722 has at least one, and typically two, water stream bypass apertures 724 formed therein and the first pressurized water stream engagement surface 720 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 720 through the water stream bypass aperture or apertures 724 . [0136] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 720 is preferably formed with a central, generally arched water flow channel 726 defined by an elongate arch 728 joining two, mutually spaced generally parallel upstanding vanes 730 , which divide surface 720 into preferably three water engagement sub-surfaces 732 , 734 and 736 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 732 , 734 and 736 is generally identical, however, alternatively, the individual sub-surfaces 732 , 734 and 736 may have different widths. Alternatively, the number of vanes 730 provided may be more or less than two. [0137] Preferably vanes 730 have increased thickness from a stream incoming edge 740 of first pressurized water stream engagement surface 720 to a stream exiting edge 742 of the first pressurized water stream engagement surface 720 . Preferably vanes 730 each have a tapered stream facing edge 744 . [0138] First water stream engagement surface 720 is preferably generally flat except for a short tapered portion adjacent incoming edge 740 . [0139] Both the first and second water stream engagement surfaces 720 and 722 are defined by side walls 750 and 752 , which join first and second water stream engagement surfaces 720 and 722 and define an open space therebetween. [0140] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 722 is preferably formed with two mutually spaced generally parallel upstanding vanes 760 which divide surface 722 into preferably three water engagement sub-surfaces 762 , 764 and 766 . [0141] In the illustrated embodiment, the width of each of water engagement sub-surfaces 762 , 764 and 766 is generally identical, however, alternatively, the individual sub-surfaces 762 , 764 and 766 may have different widths. Alternatively, the number of vanes 760 provided may be more or less than two. [0142] Preferably vanes 760 have a generally uniform thickness from a stream incoming edge 770 of second pressurized water stream engagement surface 722 to a stream exiting edge 772 of the second pressurized water stream engagement surface 722 . Preferably vanes 760 each have a tapered stream facing edge 774 . [0143] Second water stream engagement surface 722 is preferably generally curved, faces generally oppositely to first water stream engagement surface 720 and includes a generally flat portion 776 adjacent incoming edge 770 , which extends into a generally curved portion 778 , adjacent stream exiting edge 772 . [0144] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 762 and 766 , on opposite sides of water engagement sub-surface 764 , are formed with apertures extending nearly all along generally curved portion 778 and preferably along a downstream part of flat portion 776 . [0145] Reference is now made to FIGS. 8A and 8B , which are simplified side view illustrations of a hammer element 800 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 8A & 8B being mutually rotated by 180 degrees, and to FIGS. 8C and 8D , which are simplified isometric illustrations of the hammer element of FIGS. 8A and 8B , taken from two different viewpoints. Reference is also made to FIGS. 8E , 8 F and 8 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 8A , and to FIGS. 8H , 8 I, 8 J and 8 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 8A . [0146] As seen in FIGS. 8A-8K , hammer 800 preferably includes a generally central hub portion 802 that defines a cylindrical sleeve portion 804 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 802 also preferably defines a plurality of, typically four, spring mounting protrusions 806 . [0147] Extending generally forwardly from hub portion 802 is a deflector mounting arm 808 from which extends a deflector 810 . Deflector mounting arm 808 also preferably includes an attachment recess 812 and aperture 814 for optional mounting thereon of spray diffuser 212 . [0148] Extending generally rearwardly from hub portion 802 is a balancing arm 816 . [0149] Reference is now particularly made to deflector 810 and to FIGS. 8E-8K . It is a particular feature of the present invention that deflector 810 includes a first pressurized water stream engagement surface 820 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 822 , downstream of the first pressurized water stream engagement surface 820 , wherein the first pressurized water stream engagement surface 820 has a pressurized water stream channeling configuration arranged: [0150] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 820 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 822 , and [0151] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 820 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 822 . [0152] Preferably, the second pressurized water stream engagement surface 822 has at least one, and typically two, water stream bypass apertures 824 formed therein and the first pressurized water stream engagement surface 820 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 820 through the water stream bypass aperture or apertures 824 . [0153] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 820 is preferably formed with a central water flow channel 826 of generally triangular cross section defined by two mutually inclined generally parallel-extending upstanding vanes 830 , which divide surface 820 into preferably three water engagement sub-surfaces 832 , 834 and 836 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 832 , 834 and 836 is generally identical, however, alternatively, the individual sub-surfaces 832 , 834 and 836 may have different widths. Alternatively, the number of vanes 830 provided may be more or less than two. [0154] Preferably vanes 830 have increased thickness from a stream incoming edge 840 of first pressurized water stream engagement surface 820 to a stream exiting edge 842 of the first pressurized water stream engagement surface 820 . Preferably vanes 830 each have a tapered stream facing edge 844 . [0155] First water stream engagement surface 820 is preferably generally flat except for a short tapered portion adjacent incoming edge 840 . [0156] Both the first and second water stream engagement surfaces 820 and 822 are defined by side walls 850 and 852 , which join first and second water stream engagement surfaces 820 and 822 and define an open space therebetween. [0157] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 822 is preferably formed with two mutually spaced generally parallel upstanding vanes 860 which divide surface 822 into preferably three water engagement sub-surfaces 862 , 864 and 866 . [0158] In the illustrated embodiment, the width of each of water engagement sub-surfaces 862 , 864 and 866 is generally identical, however, alternatively, the individual sub-surfaces 862 , 864 and 866 may have different widths. Alternatively, the number of vanes 860 provided may be more or less than two. [0159] Preferably vanes 860 have a generally uniform thickness from a stream incoming edge 870 of second pressurized water stream engagement surface 822 to a stream exiting edge 872 of the second pressurized water stream engagement surface 822 . Preferably vanes 860 each have a tapered stream facing edge 874 . [0160] Second water stream engagement surface 822 is preferably generally curved, faces generally oppositely to first water stream engagement surface 820 and includes a generally flat portion 876 adjacent incoming edge 870 , which extend into a generally curved portion 878 , adjacent stream exiting edge 872 . [0161] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 862 and 866 , on opposite sides of water engagement sub-surface 864 , are formed with apertures extending nearly all along generally curved portion 878 and preferably along a downstream part of flat portion 876 . [0162] Reference is now made to FIGS. 9A and 9B , which are simplified side view illustrations of a hammer element 900 forming part of the sprinkler of FIGS. 1A-2B , FIGS. 9A & 9B being mutually rotated by 180 degrees, and to FIGS. 9C and 9D , which are simplified isometric illustrations of the hammer element of FIGS. 9A and 9B , taken from two different viewpoints. Reference is also made to FIGS. 9E , 9 F and 9 G, which are simplified sectional illustrations taken along respective section lines E-E, F-F and G-G in FIG. 9A , and to FIGS. 9H , 9 I, 9 J and 9 K, which are simplified sectional illustrations taken along respective section lines H-H, I-I, J-J and K-K in FIG. 9A . [0163] As seen in FIGS. 9A-9K , hammer 900 preferably includes a generally central hub portion 902 that defines a cylindrical sleeve portion 904 which is preferably sized to rotatably accommodate vertical hammer mounting shaft 196 . Hub portion 902 also preferably defines a plurality of, typically four, spring mounting protrusions 906 . [0164] Extending generally forwardly from hub portion 902 is a deflector mounting arm 908 from which extends a deflector 910 . Deflector mounting arm 908 also preferably includes an attachment recess 912 and aperture 914 for optional mounting thereon of spray diffuser 212 . [0165] Extending generally rearwardly from hub portion 902 is a balancing arm 916 . [0166] Reference is now particularly made to deflector 910 and to FIGS. 9E-9K . It is a particular feature of the present invention that deflector 910 includes a first pressurized water stream engagement surface 920 , which receives a water stream from the forward nozzle 190 , and a second pressurized water stream engagement surface 922 , downstream of the first pressurized water stream engagement surface 920 , wherein the first pressurized water stream engagement surface 920 has a pressurized water stream channeling configuration arranged: [0167] to direct a first portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 920 , which does not exceed a predetermined water stream quantity, onto the second pressurized water stream engagement surface 922 , and [0168] to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 920 , which second portion exceeds the predetermined water stream quantity, not onto the second pressurized water stream engagement surface 922 . [0169] Preferably, the second pressurized water stream engagement surface 922 has at least one, and typically two, water stream bypass apertures 924 formed therein and the first pressurized water stream engagement surface 920 is arranged to direct at least a second portion of the pressurized water stream impinging on the first pressurized water stream engagement surface 920 through the water stream bypass aperture or apertures 924 . [0170] It is also a particular feature of the present invention that the first pressurized water stream engagement surface 920 is preferably formed with two, mutually spaced generally parallel upstanding vanes 930 , having parallel mutually facing surfaces and non parallel opposite surfaces, which divide surface 920 into preferably three water engagement sub-surfaces 932 , 934 and 936 . In the illustrated embodiment, the width of each of water engagement sub-surfaces 932 , 934 and 936 is generally identical, however, alternatively, the individual sub-surfaces 932 , 934 and 936 may have different widths. Alternatively, the number of vanes 930 provided may be more or less than two. [0171] Preferably vanes 930 have a generally truncated triangular cross section and have increased thickness from a stream incoming edge 940 of first pressurized water stream engagement surface 920 to a stream exiting edge 942 of the first pressurized water stream engagement surface 920 . Preferably vanes 930 each have a tapered stream facing edge 944 . [0172] First water stream engagement surface 920 is preferably generally flat except for a short tapered portion adjacent incoming edge 940 . [0173] Both the first and second water stream engagement surfaces 920 and 922 are defined by side walls 950 and 952 , which join first and second water stream engagement surfaces 920 and 922 and define an open space therebetween. [0174] It is a further particular feature of the present invention that the second pressurized water stream engagement surface 922 is preferably formed with two mutually spaced generally parallel upstanding vanes 960 which divide surface 922 into preferably three water engagement sub-surfaces 962 , 964 and 966 . It is a particular feature of the embodiment of FIGS. 9A-9K , that vanes 960 are formed as continuations of vanes 930 , such that vanes 930 of the first pressurized water stream engagement surface 920 , vanes 960 of the second pressurized water stream engagement surface 922 and intermediate vanes 968 , each joining a vane 930 with a vane 960 , together define continuous vanes 969 , spanning both first and second pressurized water stream engagement surfaces 920 and 922 . [0175] In the illustrated embodiment, the width of each of water engagement sub-surfaces 962 , 964 and 966 is generally identical, however, alternatively, the individual sub-surfaces 962 , 964 and 966 may have different widths. Alternatively, the number of vanes 960 provided may be more or less than two. [0176] Preferably vanes 960 have a generally uniform thickness from a stream incoming edge 970 of second pressurized water stream engagement surface 922 to a stream exiting edge 972 of the second pressurized water stream engagement surface 922 . [0177] Second water stream engagement surface 922 is preferably generally curved, faces generally oppositely to first water stream engagement surface 920 and includes a generally flat portion 976 adjacent incoming edge 970 , which extend into a generally curved portion 978 , adjacent stream exiting edge 972 . [0178] It is an additional particular feature of the present invention that preferably water engagement sub-surfaces 962 and 966 , on opposite sides of water engagement sub-surface 964 , are formed with apertures extending nearly all along generally curved portion 978 and preferably along a downstream part of flat portion 976 . [0179] Reference is now made to FIGS. 10A , 10 B & 10 C, which are respective simplified front view, top view and back view illustrations of the sprinkler of FIGS. 1A-3D , showing water flows therethrough when a relatively small nozzle is employed, and to FIG. 10D , which is a simplified sectional illustration taken along lines D-D in FIG. 10A . [0180] As seen in FIGS. 10A-10D , in the illustrated embodiment, when a relatively small forward nozzle is employed, such as a nozzle 190 having an internal diameter of 2 mm, nearly all of the water stream emanating from nozzle 190 , here designated by reference numeral 1000 , is confined between vanes 330 of first water stream engagement surface 320 in engagement with first water engagement sub-surface 334 , as designated by reference numeral 1002 . Nearly all of the water stream then impinges on second water engagement sub-surface 364 , and is confined between vanes 360 of the second water stream engagement surface 322 , as designated by reference numeral 1004 . Nearly all of the water stream as designated by reference numeral 1006 exits in a direction indicated by an arrow 1008 . Accordingly, nearly all of the water stream applies a rotational force, indicated by an arrow 1010 , to hammer 300 , causing it to rotate about vertical axis 154 . [0181] Reference is now made to FIGS. 11A , 11 B & 11 C, which are respective simplified front view, top view and back view illustrations of the sprinkler of FIGS. 1A-3D , showing water flows therethrough when a relatively large nozzle is employed, to FIG. 11D , which is a simplified sectional illustration taken along lines D-D in FIG. 11A , and to FIG. 11E , which is a simplified sectional illustration taken along lines E-E in FIG. 11A . [0182] As seen in FIGS. 11A-11E , in the illustrated embodiment, when a relatively large forward nozzle is employed, such as a nozzle 190 having an internal diameter of 5 mm, a water stream 1100 emanates from nozzle 190 . In accordance with a preferred embodiment of the present invention, only part of water stream 1100 , here designated by reference numeral 1102 , is confined between vanes 330 of first water stream engagement surface 320 in engagement with first water engagement sub-surface 334 . [0183] Two side water streams, respectively designated by reference numerals 1104 and 1106 , flow outside vanes 330 in engagement with respective first water engagement sub-surfaces 332 and 336 . [0184] Nearly all of the water stream 1102 impinges on second water engagement sub-surface 364 , and is confined between vanes 360 of the second water stream engagement surface 322 , as designated by reference numeral 1110 . Nearly all of the water stream 1110 exits, as designated by reference numeral 1112 , in a direction indicated by an arrow 1114 . Accordingly, nearly all of the water stream 1112 applies a rotational force, indicated by an arrow 1116 , to hammer 300 , causing it to rotate about vertical axis 154 . [0185] The two side water streams 1104 and 1106 generally do not impinge on the second water engagement surface 364 but rather exit, as respectively designated by reference numerals 1124 and 1126 , through apertures 324 in directions respectively indicated by arrows 1134 and 1136 . The side water streams generally do not apply a rotational force to hammer 300 . [0186] It is a particular feature of an embodiment of the present invention that, as appreciated from a comparison of FIGS. 10A-10D with FIGS. 11A-11E , it is seen that the proportion of the water stream output from the forward nozzle, which applies a rotational force to hammer 300 varies as a function of the size of the forward nozzle and thus of the discharge volume of the nozzle. [0187] It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the invention includes both combinations and subcombinations of the various features described hereinabove as well as modifications and variations thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not in the prior art.

An irrigation sprinkler including a base defining an axis, a pressurized water inlet mounted onto the base, a nozzle, communicating with the inlet, and providing a pressurized water stream which is generally outwardly directed relative to the axis and a water stream deflector for engaging the pressurized water stream and deflecting at least part of the water stream azimuthally with respect to the axis, the deflector including a first pressurized water stream engagement surface and a second pressurized water stream engagement surface downstream of the first engagement surface, the first engagement surface having a pressurized water stream directing configuration arranged to direct a first portion of the stream impinging thereon, which does not exceed a predetermined quantity, onto the second surface and to direct at least a second portion of the stream impinging thereon, which at least a second portion exceeds the predetermined quantity, not onto the second engagement surface.

FIELD OF THE INVENTION [0001] The present invention generally relates to computerized methods and systems for assuring compliance with applicable laws and rules. BACKGROUND OF THE INVENTION [0002] In regulated sectors such as healthcare, finance, and accounting, laws such as the U.S. Health Insurance Portability and Accountability Act (HIPAA), the Gramm-Leach-Bliley Act, the Sarbanes-Oxley Act, and related European laws have been enacted over the past decade to establish new or enhanced standards. The length of these laws, the opacity of the legal language, and the complexity of these acts make it difficult for practitioners to determine whether they are in compliance. This complexity becomes even more significant if computer programmers and information technology professionals wish to build and configure automated systems to help business professionals comply with applicable laws. [0003] There is a need in the art for automated systems for assuring compliance with laws and rules. There is a further need to for an automated compliance checking system that is itself amenable to verifying that its programming is correct an in alignment with the applicable laws and rules. SUMMARY OF THE INVENTION [0004] The present invention makes use of a fragment of stratified Datalog with limited use of negation, and implements a specific format for compositionally representing clauses of a law as Datalog rules. An embodiment of the invention provides a framework to formalize the part of the US Health Insurance Portability and Accountability Act (HIPAA) that regulates information sharing in a healthcare provider environment. This executable formalization of legal regulation was tested by implementing a prototype web-based message system and compliance checker based on the Vanderbilt Medical Center MyHealth web portal. [0005] The formalization of the present invention was also used to examine conflicts in the HIPAA regulation. By querying the logic program to return all the possible agents who could gain access to patient information, some anomalies were found regarding lack of regulation of government employees who are granted access to medical data, for example. While the present disclosure focuses on the formalization of HIPAA, the teachings of the present invention can generally be applied to a broad class of privacy regulations. For example, it may be applied to those consistent with Nissenbaum's theory of Contextual Integrity. [0006] Those of skill in the art will appreciate that the teaching of the present invention can be applied to laws, rules, or regulations with similar structures to those of HIPAA as used as an example in the present disclosure. Indeed, the teachings of the present invention can be applied to other aspects of HIPAA not discussed here. [0007] The present invention may also be enhanced by generating meaningful annotated audit logs, as by logging messages with semantic information about each action and compliance issues associated with it. In addition to automating compliance tasks, a formal presentation of HIPAA (or other regulations) could also be useful in training medical personnel about the consequences and non-consequences of the law. These and other extensions of the present invention will be obvious to those of ordinary skill in the art without deviating from the teachings described above and claimed below. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a block diagram of a computer system on which embodiments of the present invention can be implemented. [0009] FIG. 2 is a block diagram of a distributed computing system on which embodiments of the present invention can be implemented. [0010] FIG. 3 is a flow diagram of a method according to an embodiment of the present invention. [0011] FIG. 4 is a representation of a graphical user interface according to an embodiment of the present invention. [0012] FIG. 5 is a representation of a graphical user interface according to an embodiment of the present invention. [0013] FIG. 6 is a representation of a graphical user interface according to an embodiment of the present invention. DETAILED DESCRIPTION [0014] Among other things, the present invention relates to methods, techniques, and algorithms that are intended to be implemented in a digital computer system. By way of overview that is not intended to be limiting, digital computer system 100 as shown in FIG. 1 will be described. Such a digital computer or embedded device is well-known in the art and may include variations of the below-described system. [0015] FIG. 1 is a block diagram of a system 100 configured to implement one or more aspects of the present invention. System 100 may be a computer workstation, personal computer, or any other device suitable for practicing one or more embodiments of the present invention. As shown, system 100 includes one or more processing units, such as central processing unit (CPU) 102 , and a system memory 104 communicating via a bus path that may include a memory bridge 105 . CPU 102 includes one or more processing cores, and, in operation; CPU 102 is the master processor of system 100 , controlling and coordinating operations of other system components. System memory 104 stores software applications and data for use by CPU 102 . CPU 102 runs software applications and optionally an operating system. Memory bridge 105 , which may be, e.g., a Northbridge chip, is connected via a bus or other communication path (e.g., a HyperTransport link) to an I/O (input/output) bridge 107 . I/O bridge 107 , which may be, e.g., a Southbridge chip, receives user input from one or more user input devices such as keyboard 108 or mouse 109 and forwards the input to CPU 102 via memory bridge 105 . In alternative embodiments, I/O bridge 107 may also be connected to other input devices such as a joystick, digitizer tablets, touch pads, touch screens, still or video cameras, motion sensors, and/or microphones (not shown). [0016] One or more display processors, such as display processor 112 , are coupled to memory bridge 105 via a bus or other communication path 113 (e.g., a PCI Express, Accelerated Graphics Port, or HyperTransport link); in one embodiment display processor 112 is a graphics subsystem that includes at least one graphics processing unit (GPU) and graphics memory. Graphics memory includes a display memory (e.g., a frame buffer) used for storing pixel data for each pixel of an output image. Graphics memory can be integrated in the same device as the GPU, connected as a separate device with the GPU, and/or implemented within system memory 104 . Display processor 112 periodically delivers pixels to a display device 110 that may be any conventional CRT or LED monitor. Display processor 112 can provide display device 110 with an analog or digital signal. [0017] A system disk 114 is also connected to I/O bridge 107 and may be configured to store content and applications and data for use by CPU 102 and display processor [0018] 112 . System disk 114 provides non-volatile storage for applications and data and may include fixed or removable hard disk drives, flash memory devices, and CD-ROM, DVD ROM, Blu-ray, HD-DVD, or other magnetic, optical, or solid state storage devices. [0019] A switch 116 provides connections between I/O bridge 107 and other components such as a network adapter 118 and various add-in cards 120 and 121 . Network adapter 118 allows system 100 to communicate with other systems via an electronic communications network, and may include wired or wireless communication over local area networks and wide area networks such as the Internet. [0020] Other components (not shown), including USB or other port connections, film recording devices, and the like, may also be connected to I/O bridge 107 . For example, an audio processor may be used to generate analog or digital audio output from instructions and/or data provided by CPU 102 , system memory 104 , or system disk 114 . Communication paths interconnecting the various components in FIG. 1 may be implemented using any suitable protocols, such as PCI (Peripheral Component Interconnect), PCI Express (PCI-E), AGP (Accelerated Graphics Port), HyperTransport, or any other bus or point-to-point communication protocol(s), and connections between different devices may use different protocols, as is known in the art. [0021] In one embodiment, display processor 112 incorporates circuitry optimized for graphics and video processing, including, for example, video output circuitry, and constitutes a graphics processing unit (GPU). In another embodiment, display processor 112 incorporates circuitry optimized for general purpose processing. In yet another embodiment, display processor 112 may be integrated with one or more other system elements, such as the memory bridge 105 , CPU 102 , and I/O bridge 107 to form a system on chip (SoC). In still further embodiments, display processor 112 is omitted and software executed by CPU 102 performs the functions of display processor 112 . [0022] Pixel data can be provided to display processor 112 directly from CPU 102 . In some embodiments of the present invention, instructions and/or data representing a scene are provided to a render farm or a set of server computers, each similar to system 100 , via network adapter 118 or system disk 114 . The render farm generates one or more rendered images of the scene using the provided instructions and/or data. These rendered images may be stored on computer-readable media in a digital format and optionally returned to system 100 for display. [0023] Alternatively, CPU 102 provides display processor 112 with data and/or instructions defining the desired output images, from which display processor 112 generates the pixel data of one or more output images, including characterizing and/or adjusting the offset between stereo image pairs. The data and/or instructions defining the desired output images can be stored in system memory 104 or a graphics memory within display processor 112 . In an embodiment, display processor 112 includes 3D rendering capabilities for generating pixel data for output images from instructions and data defining the geometry, lighting shading, texturing, motion, and/or camera parameters for a scene. Display processor 112 can further include one or more programmable execution units capable of executing shader programs, tone mapping programs, and the like. [0024] In one embodiment, application 150 is stored in system memory 104 . Application 150 may be any application configured to display a graphical user interface (GUI) on display device 110 . Application 150 may be configured to generate and modify documents based on input received from a user. For example, application 150 may be a word processing application or an image editing program. [0025] It will be appreciated that the system shown herein is illustrative and that variations and modifications are possible. The connection topology, including the number and arrangement of bridges, may be modified as desired. For instance, in some embodiments, system memory 104 may be connected to CPU 102 directly rather than through a bridge, and other devices may communicate with system memory 104 via memory bridge 105 and CPU 102 . In other alternative topologies display processor 112 may be connected to I/O bridge 107 or directly to CPU 102 , rather than to memory bridge 105 . In still other embodiments, I/O bridge 107 and memory bridge 105 may be integrated in a single chip. In addition, the particular components shown herein are optional. For instance, any number of add-in cards or peripheral devices might be supported. In some embodiments, switch 116 is eliminated, and network adapter 118 and add-in cards 120 , 121 connect directly to I/O bridge 107 . [0026] An embodiment of the present invention provides a method for representing and processing laws, rules, regulations, and policies in a messaging system. Among other things, the present invention provides a method for representing and processing privacy laws and compliance to such laws is provided. [0027] The U.S. Health Insurance Portability and Accountability Act (HIPAA) title II was enacted in 1996. In an embodiment of the present invention, HIPAA regulations in a messaging system are described. As shown in FIG. 2 , health providers desire to pass messages among doctors 202 , nurses 204 , and patients 206 , for example, through a centralized message server 200 . To address certain privacy concerns, however, such messages must be closely controlled so as to assure compliance with such laws as HIPAA. Towards meeting this need, the present invention provides a novel approach for implementing a privacy policy on server 100 so as to reasonably assure compliance. [0028] The HIPAA regulation is complex for non-experts to follow for a number of reasons. For example, the law generally allows protected information to be shared between appropriate entities for the purpose of treatment. But clause 164.508.a.2, for example, apparently contradicts this by stating that if the protected information is a psychotherapy note then a covered entity, e.g., a health plan, a health care provider or a clearinghouse, must obtain an authorization before disclosure. Thus, simple reasoning based on actions allowed by one portion of the law, without accounting for prohibitions in other portions of the law, may give erroneous results. [0029] The present invention provides a formalization of applicable parts of the HIPAA regulation in a form that can be used in a messaging system. Through Web access to a centralized system, such a messaging system allows patients and medical professionals to exchange messages and, as necessary, request and view information such as prescriptions or lab test results. [0030] The present invention can also be used in such systems to respond to requests from other hospitals and clinics, law enforcement, insurers, and other organizations. A compliance module that decides, as messages are composed or entered into the system, whether a message complies with HIPAA is disclosed. The present invention can further be extended and modified as HIPAA and other applicable laws are modified or supplemented. [0031] Starting with a view of privacy policy, business processes, and compliance, an embodiment of the present invention implements a stratified fragment of the logic programming language Prolog with limited use of negation. [0032] In addition to representing HIPAA precisely enough to determine whether any particular action within the scope of the messaging system would comply with the applicable law, the present invention provides a formalization that is verifiable by lawyers, medical, and computer professionals alike. For this reason, the present invention formalizes the law so that the Prolog presentation can be read and understood section by section, with the meaning of the entire presentation determined in a systematic way from the meaning of its parts. In addition to supporting outside review and audit, this approach also allows HIPAA formalization to be combined with additional policies adopted by regulated enterprises. [0033] An embodiment of the present invention focuses on a specific privacy law, identification of a specific fragment of stratified Datalog that appears appropriate to the task, and a reliance on a general theory of privacy previously articulated for a more expressive but less commonly implemented logical framework. [0034] The present invention identifies a specific fragment of stratified Datalog with one alternation of negation which suits the present invention and supports a certain degree of policy compositionality. The present invention uses this framework to formalize the part of the HIPAA law that regulates information sharing in a healthcare provider environment. The structure of logic programming with predicates, query, and facts correspond to the legal clauses, actions being performed, and relations like roles defined in the law. As a subset of logic programming, the methods of the present invention facilitate the addition of cross references as present in the law. [0035] The present invention also implements a prototype compliance checker and message system as a web-based system. This embodiment is used to decide if a message that a practitioner is about to send is in compliance with the HIPAA regulation. The present invention is also used to examine conflicts in the HIPAA regulation. [0036] While the present invention focuses on the formalization of HIPAA, those of skill in the art will appreciate that the teachings as presented herein apply generally to a broad class of privacy regulations. More generally, the present invention can be applied to other laws, rules, and regulations with an appropriate structure that are used to control actions. [0037] In the present disclosure, the key features and structure of the HIPAA policy and an information sharing model of the present invention will be introduced and summarized. Next, the modified computer language as used in the present invention to model the HIPAA policy and the rule composition approach will be described. [0038] HIPAA both explicitly permits certain transfers of personal health information and prohibits some disclosures. For example, HIPAA provides federal protections for personal health information held by covered entities and gives patients an array of rights with respect to that information. Also, HIPAA regulates the use and disclosure of personal health information. [0039] In HIPAA terminology, a covered entity is a health plan, a health care clearinghouse, or a health care provider that transmits health information in electronic form. Protected health information is individually identifiable health information that is transmitted or maintained in electronic or other media. [0040] For purposes of describing features and aspects of the present invention, the present disclosure focuses section 164 of HIPAA, which regulates the security and privacy issues in the health care industry. One of skill in the art, however, will appreciate that the teachings provided herein are not so limited and can actually be extended to many other applications with appropriately structured laws, rules, or regulations, for example. [0041] An embodiment of the present invention covers general provisions, security standards for the protection of electronic health information, and privacy of individually identifiable health information. The present disclosure specifically addresses subpart 164.502, which covers the general rules for uses and disclosures of protected health information. Of the many subparts it references, the present disclosure considers subpart 164.506, which covers uses and disclosures to carry out treatment, payment, or health care operations, and subpart 164.508, which covers uses and disclosures requiring an authorization. [0042] Shown in FIG. 3 is method for checking compliance with a law such as HIPAA laws according to an embodiment of the invention. Although the method is described in conjunction with the various system representations set forth herein, persons skilled in the art will understand that any system that describes the method steps, in any order, falls within the scope of the present invention. [0043] As shown at step 302 , a desired action is determined. In an embodiment of the invention described further below, the desired action is sending a message that is subject to laws or rules, but other actions can also be processed according to the teachings of the present invention. For example, any action for which there exist certain structured rules is appropriate for implementation according to the teachings of the present invention. [0044] At step 304 , necessary information is then gathered so that determinations can be made as to whether the desired action is to be allowed or forbidden. In an embodiment for a messaging system as described further below, the information collected at step 304 includes To (e.g., to whom a message is addressed), From (e.g., from whom a message is sent), About (e.g., about what is the message), Type (e.g., type of message), Purpose (e.g., purpose of the message), In Reply To (e.g., information about whether the present message is in reply to another message), Consented By (e.g., the person who consented to the message), and Belief (e.g., information about whether the sender has a belief about the subject message). [0045] Shown in FIG. 4 are certain aspects of a graphical user interface (GUI) as may be implemented in accordance with the teachings of the present invention. As shown, screen 402 provides an interface by which the contents of a desired message may be entered. This screen seeks to provide a straightforward for inputting the broad range of patient messages. Shown in FIG. 4 is to field 404 , From field 406 , About field 408 , Type field 410 , and Purpose field 412 . Also show in FIG. 4 is drop down menu 420 for Purpose field 412 . Drop down menus can also be implemented for the other fields of the present invention. Other input techniques are likewise possible in other embodiments of the present invention. Further shown in FIG. 5 are Belief field 414 , and Message field 416 . It should be noted that fields 414 and 416 as well as other fields can also be included in screen 402 of FIG. 4 . [0046] According to an embodiment of the invention to be described further below, the To and From fields indicate the recipient and sender of the message. The About field identifies whose personal health information is contained in the message. The Type field defines, for example, the type of healthcare information mentioned in the message. Further examples include blood tests, X-ray results, or psychotherapy notes. [0047] The Purpose field indicates a reason the message is being sent, such as for medical treatment. When the purpose is needed to determine compliance, the present invention assumes that a professional has asserted a purpose, or an asserted purpose is in some way inferred and made available as input to the compliance module. In an embodiment, the present invention infers when a purpose is needed, and provides the sender with a pulldown menu indicating purposes that would allow the message to be sent. [0048] The In Reply To field describes a disclosure where the message is sent as a response to some earlier message. The Consented By field indicates which people have consented to the message disclosure. [0049] The Belief field contains a collection of assertions about the current situation, such as whether this is a medical emergency, or whether disclosure is (in the opinion of the sender) in the best interest of the health of the patient. Some beliefs may not be indisputable facts in the sense that another person may think differently. But a sender may assert a belief (e.g., from a pulldown menu) or the sender's belief may be established by some other means. In an embodiment, once a message is allowed based on a belief, this reason is recorded and made available to a subsequent audit. [0050] Turning back to the method of FIG. 3 , at step 306 , a determination is made as to whether the desired action is permitted by certain of the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether a desired action is permitted by all the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may only require that a certain subset of laws or rules allow a particular action. [0051] At step 308 , a determination is made as to whether the desired action is forbidden by certain of the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether a desired action is forbidden by at least one of the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may allow a particular action a condition exists where one law or rule allows an action but another law or rule forbids the action. Other manners of addressing conflicts in laws and rules are discussed further below. [0052] At step 310 , a determination is made as to whether an exception applies to the desired action as set forth in the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether an exception applies to a desired action that, for example, takes precedence over the results of steps is forbidden by at least one of the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may allow a particular action a condition exists where one law or rule allows an action but another law or rule forbids the action. Other manners of addressing conflicts in laws and rules are discussed further below. [0053] In an embodiment, patients or professionals enter a message into a centralized message system as shown in screen 402 of FIG. 4 . In this embodiment, the centralized message system can deliver the message by making it visible to other users. Messages may be simple questions from a patient, or may contain lab test results or other forms of protected medical information. Given information about the message, and other information such as the roles of the sender and receiver in the hospital, the HIPAA compliance module of the present invention decides whether delivery of the message complies with HIPAA. Thus, upon entering the appropriate information at screen 402 , a user may be presented with screen 502 that, after execution certain methods of the present invention, notifies the user that the message was in compliance with HIPAA regulations and was sent. Screen 602 , however, is presented if, after execution of certain methods of the present invention, a message is either forbidden or not permitted by HIPAA regulations and the message is not sent. [0054] A structure of the present invention that provides for the formalization of laws, rules, regulations, and policies such as contained in HIPAA will now be described. Among other things, this embodiment of the present invention is designed to make compliance decisions based on eight message characteristics: To, From, About, Type, Purpose, In Reply To, Consented By and Belief. One of ordinary skill in the art will, however, understand how the discussion below can be modified without deviating from the teachings of the present invention. [0055] Action: For the purpose of determining compliance, a message action is represented as an eight-tuple a= u src ,u dst ,u abt , m typ , m pur , a reply , c, b , where (note that underlining indicates a set) [0000] u src , u dst , u abt ε U (the set of users or agents), m typ ε T (the set of types of messages), m pur ε P (the set of purposes), a reply ε A (the set of actions), C = < u by , c type > ε C (the tuple of consents) with u by ε U (the set of users) and c typ ε CT (the set of consent types), b = < u by , U abt , b f > ε B (the set of beliefs) with u by , u abt ε U (the set of users) and b f ε BF (the set of beliefs). [0056] In this embodiment, a HIPAA policy is a function from actions to Booleans (true or false), indicating permission or prohibition. [0000] U×U×U×T×P×A×C×B→{T,F} [0057] Category: A category is a set of field values defining the conditions when a legal clause is applicable to a particular action. For example, one common category of actions is those with type indicating protected health information and purpose indicating medical treatment. [0058] Subcategories: Some field values may indicate that the action belongs to a subcategory of another category of actions. For example “psychotherapy note” is a subtype of “health records,” which implies that policy about health records could also affect decisions about psychotherapy note, but not vice versa. More generally, the possible values associated with any field may be partially ordered. [0059] Roles: While it is possible to express policy about specific individuals, HIPAA policies are written using roles. For example, an individual could be a nurse or a doctor. When an action is considered, the system of the present invention receives the names of the sender and recipient, for example, and then uses information about the hospital to determine the respective role(s). For patients, similar processing (formalized in Prolog) is used to determine whether the patient is an adult or a minor. [0060] Further concepts for the formalization of HIPAA are introduced using 164.508.a.2 of HIPAA as a running example. As stated above, 164.508 as a whole governs uses and disclosures of protected health information that require an authorization. Specifically, 164.508.a.2 states, among other things, that a covered entity must obtain an authorization for any use or disclosure of psychotherapy note, except if it is to be used by the originator of the psychotherapy note for treatment. [0061] Requirement: An action that falls into the category of a legal clause is allowed only if the requirement in the clause is satisfied. For example, 164.508.a.2 states that the specified action is allowed only if an authorization is obtained. [0062] Exception: An exception in a legal clause qualifies its category. For example, 164.508.a.2 states that if the purpose of the action is for use by the originator of the psychotherapy note for treatment, then the requirement does not apply. [0063] Clause vs. Rule: For ease of exposition, a labeled paragraph in the HIPAA law is called a clause, and its translation into logic rules. [0064] To illustrate this terminology, a clause with category given by predicate a, requirement predicate c and exceptions e can be expressed as the following rules: [0000] permitted_by R ( a e ) c [0000] forbiddent)by R ( a e ) c [0000] R_not_applicable a e [0065] Combination: A central concept in the approach of the present invention is the manner in which a policy composed of several legal clauses is expressed by a combination of the associated permitted_by and forbidden_by rules. Given rules R1 . . . Rm, any action is consistent with the policy of these rules if it is permitted by at least one of the rules and not forbidden by any of them. [0000] compliant_with R1 . . . Rm (permitted_by R1 . . . permitted_by Rm ) (forbiddent_by R1 . . . forbiddent_by Rm ) [0066] This approach allows each clause to be translated into rules that are then combined in a systematic way to express the requirements of the law. [0067] Cross-Reference: Frequently a requirement of a clause involves a reference to other clauses of the law. In the formal definition discussed below, the present invention requires an acyclicity condition so that the cross-reference relation among HIPAA clauses forms a directed acyclic graph. [0068] A fragment of stratified Datalog is identified with one alternation of negation, which is referred to for simplicity as pLogic, which suits the present formalization approach and supports a certain degree of policy compositionality. It is designed so that, given an action, the present invention can verify whether the action is compliant with the written policy. [0069] The method of the present invention for translating HIPAA into stratified Datalog with one alternation of negation is structured according to the form of pLogic rules and pLogic policies given below. As is standard in logic programming, a predicate is a symbol with an associated arity. Because the present invention uses only Datalog, a term is a variable (starting with an upper-case letter) or an object constant (starting with a lower-case letter). An atom is an n-ary predicate applied to n terms. A literal is an atom. An expression is ground if it contains no variables. [0070] Intuitively, a pLogic rule is a translation of a HIPAA clause into permitted and forbidden conditions. Each rule R therefore gives conditions on predicates permitted_by R or forbidden_by R , taking actions as arguments, indicating whether the action should be allowed or denied. pLogic facts may be used to define subsidiary predicates or other inputs to the compliance process. [0071] pLogic Facts: A pLogic fact is an atom gi(a1, . . . , an) written using any relation gi of arity n. [0000] pLogic Rule: The pLogic rules associated with a HIPAA clause Ri possibly cross-referencing clauses Rj, . . . , Rk have the form: [0000] permitted_by Ri ( A ) category — Ri ( A ) exception — Ri ( A ) requirement — Ri ( A ) (permitted_by Rj ( A ) op i,j+1 . . . op i,k permitted_by Rk ( A )) [0000] forbidden_by Ri ( A ) category — Ri ( A ) exception — Ri ( A ) (requirement — Ri ( A ) forbiddent_by Rj ( A ) . . . forbidden_by Rk ( A )) [0072] where permitted_by Ri , forbidden_by Ri , category_R i , exception_R i and requirement_R i are predicates on actions, each op i,x is either the (AND) or the (OR) operator, as specified in the corresponding legal clause in HIPAA, category_Ri, exception_Ri and requirement_Ri may appear as the head of additional Datalog rules considered to be part of the rule expressing the clause, Every variable in the body must appear in the head, As indicated, permitted_by Ri may depend on permitted_by Rj for another clause R j , but not forbidden_by Rj , and similarly forbidden_by Ri may depend on another forbidden_by Rj but not permitted_by Rj . [0078] In the definition given above, the requirements are considered to be both may and must. However, the definition could easily be generalized to put one requirement in the permit rule and another in the forbid rule. [0079] pLogic Policy: An pLogic policy is a set Δ of pLogic rules and pLogic facts whose dependency graph (defined below) is acyclic. [0080] The dependency graph V, E of Δ is defined as follows. The vertices V are predicates occurring in Δ and E contains a directed edge from u to v exactly when there is a rule in Δ where the predicate in the head is u and the predicate v appears in the body. The acyclicity condition ensures a nonrecursive stratified Datalog program. [0081] Entailment for pLogic is based on the usual stratified semantics from deductive databases and logic programming. pLogic policy is decidable pLogic policy is a nonrecursive logic program with negation and without function constants. Restricting the arity of the predicates to a constant reduces the complexity to polynomial time. [0082] pLogic is designed so that prohibition takes precedence over permission. But care must be taken in translating HIPAA into pLogic when it comes to overlapping clauses. Two rules are said overlap if the category and exceptions of the two rules allow them to apply to the same action, and one is a subcase of the other if its category and exception make it apply to every action satisfying the category and exceptions of the other. Two overlapping rules conflict if one permits an action while another forbids it; two rules are disjoint if there exists no action to which both apply. [0083] Some example relationships between rules are illustrated in Table 1. All three rules presented in the table are pairwise overlapping. But only rule R 502a1ii has a category that is a subcategory of another, specifically rule 502a1v. [0000] Category Requirement A from A type A purpose A consent R 502a1ii + covered entity health records treatment * permitted_byR506(A) − covered entity health records treatment * forbidden_byR506(A) R 502a1v + covered entity health records * * permitted_byR506(A) − covered entity health records * * forbidden_byR506(A) R 508 + * psy-therapy note * <x, authz> − * psy-therapy note * <x, authz> Table 1 Examples of Overlapping Rules in HIPAA [0084] Based on experience with HIPAA, when two rules are disjoint or overlapping, but neither is a subcase of the other, the general approach of the present invention provides the correct results: an action is permitted if it is permitted by at least one rule and not forbidden by any. When one clause addresses a subcase of another, it often appears to be the expressed intent of the law to have the more specific clause take precedence over the other clause. In other words, it appears correct to disregard both the permitted and forbidden conditions of the less specific clause, and use only the more specific clause. The present invention can handle this correctly within pLogic, by using exceptions to narrow the scope of the less specific rule so that it is not applied in the conflicting subcase. [0085] Generally, disregarding the added complexity of cross-references and exceptions, conflicts happen when the category of an action matches two or more rules, the requirement for one rule is satisfied and the requirement for the other is violated. In the above example, an action like [0086] from: covered entity, type: health records, for: treatment, requirement: —as satisfying R 506 [0000] is permitted by R 502a1ii but forbidden by R 502a1v . Because this embodiment of the invention is designed to give precedence to parts of the law that forbid an action, an action that is permitted by one of two overlapping rules and forbidden by the other will be considered forbidden. Of course, other prioritizations of laws and rules may generate different results. [0087] In cases where one rule specifies a category that is a proper subset of the category of another rule, giving precedence to denial may be incorrect because the more specific clause of the law was intended to have higher priority. A way to modify the translation of the law into rules is to add exceptions to the more generic rule to make the two rules disjoint. In the example illustrated above (in the table), an exception to rule R 502a1ii is added specifying for: treatment. This causes rule R 502a1ii not to be applied when the purpose is treatment, eliminating the problematic conflict. Another solution is to assign priorities and split all the overlapping rules to make them disjoint. If applied throughout, the alternative approach could produce a more efficient compliance checker, but requires substantial effort to properly split all rules because many HIPAA rules are overlapping. [0088] Additionally, the approach of the present invention has the advantage that it better preserves the correspondence between the logic rules and the corresponding legal clauses. To elucidate the structure of HIPAA and its translation in logic an example is provided in the appendix. [0089] Other embodiments of the present invention involve audit, implicit information, and obligations. As mentioned above in connection with beliefs asserted by the sender of a message, compliance decisions depend on the accuracy of the information provided by the users. Users of a hospital medical system are generally professional practitioners who will provide correct information. But there may be some instances in which faulty or questionable information is entered. To provide accountability, auditing systems can be added to provide trace logs of how decisions are made and when beliefs or other potentially questionable input is used. [0090] Another embodiment of the present invention can infer relevant information to reduce the amount of information the user has to provide to send a message. This can be achieved by extracting information from the message itself or by reasoning about the context of an action and information in previous messages among other things. [0091] Since obligations to perform future actions arise in many privacy contexts, the approach of the present invention can be applied to support broader obligations. While the present invention represents the past explicitly through the in-reply-to field of messages, which produces linked structures of relevant past actions, future obligations may require an additional approach. But Although Prolog and Datalog do not have a concept of past or future, one method of providing a chronology can be to periodically run a scheduled process which scans the log and checks whether, for any particular action, any further action is required. The concerned person can then be notified. [0092] An example for encoding a law such as HIPAA will now be provided. The teachings of the present example, can be extended to other HIPAA laws. Indeed, the present teachings can be extended to many other applications. [0093] In this example, a part of clause R164.502 is considered which states that a covered entity can give out health records if it adheres to R 502b or R 506a2 and satisfies additional conditions: [0094] 164.502.b Standard: Minimum necessary 164.502.b.1 Minimum necessary applies. When using or disclosing protected health information or when requesting protected health information from another covered entity, a covered entity must make reasonable efforts to limit protected health information to the minimum necessary to accomplish the intended purpose of the use, disclosure or request. 164.502.b.2 Minimum necessary does not apply. This requirement does not apply to: (i) Disclosure to or requests by a health care provider for treatment; [0100] In short, R 502b implies that when the covered entity is giving out the information to another covered entity, it should ensure that it is minimal information except for the purposes of treatment. Thus, the category for this clause is from: covered entity and to: covered entity and type: health records. The requirement is belief: minimal. The exception is for: treatment. [0101] 164.502 Uses and disclosures of protected health information. 164.502.a Standard. A covered entity may not use or disclose protected health information, except as permitted or required by this subpart or by subpart C of part 160 of this subchapter. 164.502.a.1 Permitted uses and disclosures. A covered entity is permitted to use or disclose protected health information as follows: (ii) For treatment, payment, or health care operations, as permitted by and in compliance with 164.506; [0105] The clause R 502aii implies that when a covered entity is sending health records for the purposes of treatment then it should also comply with R 506 . Here the category is from: covered entity and type: health records and purpose: treatment. The requirement is to comply with R 506 . [0106] Thus the logic translation of the two clauses is: [0107] Rules:— [0000] permitted_by 502b (A)   (A from = covered entity)   (A type =health records)   (A to =covered entity)   (A purpose =treatment)   (A belief =minimal) forbidden_by R502b (A)   (A from =covered entity)   (A type =health records)   (A to =covered entity)   (A purpose =treatment)   (A belief =minimal) permitted_by R502aii (A)   (A from =covered entity)   (A type =health records)   (A purpose =treatment)   forbidden_by R506 (A) [0108] Policy:— [0000]   compliant_with HIPAA    permitted_by 502b    permitted_by R502aii    (forbidden_by R502b    forbidden_by R502aii ) [0109] Attributes:— [0110] Attributes and relations are defined. Consider a relation called in Role that identifies a particular individual and their role. Consider the example where dr_cox, a doctor, and carla, a nurse, work at a hospital, Sacred Heart. [0000] inRole(Carla, nurse) inRole(dr_cox, doctor) inRole(doctor, covered entity) inRole(nurse, covered entity) inRole(sacredHeart, covered entity) employeeOf(sacredHeart, dr_cox) employeeOf(sacredHeart, dr_cox) [0111] A transitive closure of these rules is also possible which would imply that carla and dr_cox are a covered entity. [0112] Given this policy and the list of attributes, assuming dr_cox and carla work for the same hospital and R 506 is satisfied, an action that would be allowed with this particular rule system is: [0113] (from: carla, to: dr_cox, type: health records, for: treatment) [0114] The policy would permit this action because of the rule R 502aii An action like [0115] (from: carla, to: xyz, type: health records, for: treatment) [0000] would not be allowed as there is no relation stating that xyz is some kind of covered entity and there is no other rule in the policy permitting this action. [0116] It should be appreciated by those skilled in the art that the specific embodiments disclosed above may be readily utilized as a basis for modifying or designing other techniques for carrying out the same purposes of the present invention. It should also be appreciated by those skilled in the art that such modifications do not depart from the scope of the invention as set forth in the appended claims.

The complexity of regulations in healthcare, financial services, and other industries makes it difficult for enterprises to design and deploy effective compliance systems. The present invention supports compliance by using formalized portions of applicable laws to regulate business processes that use information systems. An embodiment of the present invention uses a stratified fragment of Prolog with limited use of negation to formalize a portion of the US Health Insurance Portability and Accountability Act (HIPAA). An embodiment of the invention provides for deployment in a prototypical hospital that implements a Web portal messaging system.

FIELD OF THE INVENTION The present invention relates generally to high-performance amplifiers for communications applications, and specifically to highly-linear broadband amplifiers. BACKGROUND OF THE INVENTION Modern mobile communications systems use multiple channels, closely spaced over an assigned frequency band. In order to avoid intermodulation products and spectral regrowth, both in and out of band, it is essential that RF power amplifier circuits used in these systems be highly linear. A high level of linearity is also required in single-channel transmitters which transmit a wideband, variable-envelope signal, such as a CDMA signal. A major source of nonlinearity is distortion, which occurs due to nonlinear amplitude and phase response of the amplifier, particularly as power nears the saturation level. Third-order distortion nonlinearities typically give the strongest intermodulation products, but fifth- and even seventh-order products can be significant. Since a typical cellular communications band has a spectral width of around 25 MHz, high-order intermodulation products in a wideband base station amplifier with large channel spacing can create distortion over a band that is more than 150 MHz wide. One method of correcting for amplifier distortion, and thus improving linearity, is predistortion, in which a controlled, nonlinear distortion is applied to the amplifier input signals. Predistortion circuitry is designed to give nonlinear amplitude and phase characteristics complementary to the distortion generated by the amplifier itself, so that ideally, the distortion is canceled in the amplifier output over the entire signal bandwidth. A feedback connection is generally provided from the amplifier output to the predistortion circuitry, for use in adjusting predistortion coefficients for optimal linearization. Predistortion is often applied to baseband signals, as described, for example, in U.S. Pat. No. 4,291,277, which is incorporated herein by reference. The predistorted signals are then upconverted and fed to the power amplifier. Predistortion may also be combined with other methods of linearization, such as feedforward error correction, as described in U.S. Pat. No. 5,760,646, which is likewise incorporated herein by reference. Various schemes have been proposed for digital-domain predistortion of the baseband signals. Because of the very high bandwidth of the intermodulation products, as mentioned above, extremely fast, wideband processing circuitry has been required in order to compensate effectively for distortion without causing new problems such as aliasing. The required sampling rate is particularly high when the power amplifier has a significant level of high order (fifth or seventh order) intermodulation response. For example, U.S. Pat. No. 4,700,151, which is incorporated herein by reference, describes a predistortion system that operates on baseband signals. The signals are sampled and then interpolated to generate samples having a higher sample rate, thus providing an extended bandwidth as required for effective predistortion. U.S. Pat. No. 5,650,758, also incorporated herein by reference, describes a pipeline architecture for a wideband digital predistortion circuit. Other predistortion schemes are described in an article by Cavers, entitled “Amplifier Linearization Using a Digital Predistorted with Fast Adaptation and Low Memory Requirements,” published in IEEE Transactions on Vehicular Technology, vol. 39, no. 4 (November 1990), pages 374-382, which is incorporated herein by reference. SUMMARY OF THE INVENTION It is an object of some aspects of the present invention to provide an improved predistortion circuit for use in amplification of radio frequency signals. It is a further object of some aspects of the present invention to provide a digital predistortion circuit that operates at a reduced sample rate relative to predistortion circuits known in the art. In preferred embodiments of the present invention, an input signal having a given initial bandwidth is processed by a digital predistortion circuit and is then converted to analog form, upconverted and amplified by a radio frequency (RF) power amplifier. The predistortion circuit receives a stream of samples of the input signal and interpolates the samples to effectively increase the sample bandwidth to an expanded bandwidth at least twice the given bandwidth of the signal. A nonlinear correction is applied to predistort the interpolated samples. The predistorted samples are then low-pass filtered and decimated, so that the bandwidth of the sample stream output by the digital predistortion circuit is again reduced to be on the order of the initial bandwidth. As a result of this design, digital/analog converters and other circuit elements operating on the output sample stream can work at a substantially slower sample rate and narrower signal bandwidth than in predistortion schemes known in the art, in which the expanded bandwidth is maintained throughout. The present invention can thus be made substantially less costly and complex than such schemes. Alternatively or additionally, it can be made to work with signal bandwidths that known predistortion schemes cannot handle with readily available hardware. The sample stream that is output by the predistortion circuit is corrected for distortion by the amplifier within the reduced bandwidth of the predistortion circuit output, but not for additional intermodulation products that typically occur over the rest of the expanded bandwidth. Consequently, the power amplifier may generate substantial distortion products in the wings of the extended bandwidth, outside the reduced-bandwidth region in which the distortion is corrected by the predistortion circuit. The uncorrected distortion products in the wings are preferably suppressed by a bandpass filter at the output of the power amplifier, substantially without affecting the amplified signals within the given bandwidth. Thus, the present invention can be used to correct for distortion that extends over substantially any bandwidth, including intermodulation products both inside and falling partially outside the given bandwidth of the signals. In-band distortion suppression of the amplifier is performed by the predistortion mechanism, whereas the out-of-band distortion is filtered by the band-pass filter. In many applications a band-pass filter or duplexer is already present at the output of the amplifier, so that no extra hardware is needed for this purpose. In some preferred embodiments of the present invention, the digital predistortion circuit operates on baseband signals, whereas in other embodiments, the predistortion circuit is configured to operate on intermediate frequency (IF) signals. The nonlinear correction may be applied to the signals using any suitable form of digital signal processing, including both real- and complex-domain (I/Q or polar) processing. Preferably, the nonlinear correction is applied using a parallel processing architecture, whereby two or more samples are processed simultaneously, in order to accommodate the high sample rate of the expanded bandwidth. In some preferred embodiments of the present invention, digital predistortion as described herein is applied in conjunction with other methods of amplifier linearization, such as feedforward correction of the signals. Most preferably, a feedforward amplifier with digital signal equalization is used, as described in U.S. patent application Ser. No. 09/226,709, which is assigned to the assignee of the present patent application and incorporated herein by reference. There is therefore provided, in accordance with a preferred embodiment of the present invention, linearization circuitry for predistortion of an input signal to an amplifier having a given distortion characteristic, including: a correction circuit, which receives a stream of samples of the input signal at a high sample rate and which applies a correction to the samples responsive to the given distortion characteristic; and a decimation circuit, which receives the corrected samples from the correction circuit and reduces the sample rate of the stream for output to the amplifier, to a reduced rate substantially less than the high sample rate. Preferably, the circuitry includes an interpolator, which receives the stream of samples at an input sample rate less than the high sample rate, and which up-samples the stream to the high sample rate. Further preferably, the correction circuit determines a characteristic of the samples and selects one or more correction coefficients responsive to the characteristic, wherein the one or more correction coefficients preferably include complex coefficients. Preferably, the characteristic of the samples includes a power level thereof. In a preferred embodiment, the correction circuit includes a plurality of parallel processing channels, to which the samples are routed in alternation, wherein at least two of the plurality of processing channels preferably read the coefficients from a common look-up table. Further preferably, each of the parallel processing channels operates on the samples at a sample rate substantially less than the high sample rate. Preferably, the decimation circuit includes a low-pass filter and a decimator. Preferably, the signal output by the circuitry is modulated and amplified by means of the amplifier, and following amplification, the signals are bandpass filtered to suppress distortion products of the amplifier outside a reduced bandwidth corresponding to a Nyquist zone of the reduced sample rate of the filtered stream. Most preferably, the amplifier generates the distortion products over a bandwidth substantially greater than the reduced bandwidth, but generally contained within a high bandwidth corresponding to a Nyquist zone of the high sample rate. Preferably, the high sample rate is at least twice the reduced sample rate, and more preferably at least four times the reduced sample rate. There is also provided, in accordance with a preferred embodiment of the present invention, linearized amplification apparatus for amplifying an input signal, including: digital processing circuitry, which includes: a correction circuit, which receives a stream of samples of the input signal at a high sample rate and applies a predistortion correction to the samples; and a decimation circuit, which receives the corrected samples from the correction circuit and reduces the sample rate of the stream to a reduced rate substantially less than the high sample rate; a modulator, which generates a modulated signal responsive to the sample stream from the digital correction circuitry; and an amplifier, which amplifies the modulated signal, such that distortion in a signal band within a Nyquist zone corresponding to the reduced sample rate is substantially reduced. Preferably, the apparatus includes a low-pass filter, which filters the amplified signal to suppress distortion products outside the signal band. Further preferably, the predistortion correction is determined responsive to a distortion characteristic of the amplifier. Preferably, the apparatus includes a digital/analog converter, which converts the digitally-processed samples to analog signals at the reduced sample rate. There is moreover provided, in accordance with a preferred embodiment of the present invention, a method for linearization of an amplifier having a given distortion characteristic, including: receiving a stream of samples of an input signal, the stream having a high sample rate; applying a predistortion correction to the samples responsive to the given distortion characteristic; reducing the sample rate of the stream of corrected samples to a reduced rate substantially less than the high sample rate; and outputting the corrected, filtered samples for amplification by the amplifier. Preferably, receiving the stream of samples includes receiving a stream of samples having an input sample rate less than the high sample rate and up-sampling the stream to the high sample rate. Further preferably, reducing the sample rate comprises low-pass filtering and decimating the corrected samples. Preferably, outputting the samples includes converting the corrected samples from digital to analog form and modulating the samples at a radio frequency. The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram illustrating radio frequency amplifier apparatus including digital predistortion circuitry, in accordance with a preferred embodiment of the present invention; FIGS. 2A-2F are graphs that schematically illustrate spectra of digital signals in the apparatus of FIG. 1; FIGS. 3A-3D are graphs that schematically illustrate spectra of analog signals in the apparatus of FIG. 1; FIG. 4 is a schematic block diagram illustrating a nonlinear correction circuit for use in the apparatus of FIG. 1, in accordance with a preferred embodiment of the present invention; FIG. 5 is a schematic block diagram showing details of predistortion circuitry, in accordance with a preferred embodiment of the present invention; and FIG. 6 is a schematic block diagram showing details of predistortion circuitry, in accordance with another preferred embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram illustrating radio frequency amplification apparatus 20 , including digital predistortion circuitry 21 and a power amplifier 34 , in accordance with a preferred embodiment of the present invention. Apparatus 20 receives baseband signals, preferably in the form of a digital stream of I and Q signal samples having a given initial bandwidth, and generates an amplified radio frequency (RF) output to an antenna. The apparatus is particularly suited for use in the context of a wideband, multi-channel amplifier system in a cellular base station and is preferably, although not necessarily, integrated with other amplification and linearization elements as are known in the art. Most preferably, apparatus 20 is integrated with a feedforward amplifier, and particularly with a feedforward amplifier that includes digital equalization, as described in the above-mentioned U.S. patent application. The I and Q baseband signals are input to respective interpolators 22 , which up-sample the signals by an interpolation ratio N 1 , wherein preferably N 1 =2 or 4, and are then filtered by low-pass filters 23 . For each pair of samples, a nonlinear corrector 24 determines a power level and, optionally, other signal characteristics, such as the phase, and applies a predistortion correction responsive to a measure of the distortion introduced by amplifier 34 . The interpolation performed before nonlinear correction effectively expands the processing bandwidth of the correction. Such expansion is generally needed to satisfy the requirement that the predistorted signals be band-limited to within the (expanded) bandwidth in which the nonlinear correction is being performed. Otherwise, aliasing products may be produced. In some applications, however, a certain amount of aliasing is permitted, in which case the predistorted signal may have some spectral density outside the expanded bandwidth, as long as it is no greater than the permitted level. Generally, the nonlinear correction is based on a function which is inverse to the nonlinear distortion of the amplifier. Preferably, the appropriate correction is based on coefficients read from a look-up table (LUT), whose contents are calculated and updated responsive to a feedback sample 38 taken from the amplifier output, as is known in the art. Suitable methods for generating predistortion coefficients are described, for example, in the references cited in the Background of the Invention. Although in preferred embodiments described hereinbelow, the predistortion coefficients are selected based on the signal power, substantially any suitable predistortion function may be used for this purpose. For instance, nonlinear corrector 24 may calculate both magnitude and phase of each complex sample (I,Q pair) and use a two-dimensional LUT to generate correction coefficients as a function of both amplitude and phase. Alternatively, an estimated predistortion polynomial or other computed function may be used instead of a look-up table. Following nonlinear correction, the samples are filtered by low-pass filters 26 and then are decimated by decimators 28 with a decimation ratio N 2 . Although filters 26 and decimators 28 are shown in the figure as separate blocks, it is also possible to implement them in a common filter unit for each of the I and Q channels. Preferably, the decimation ratio N 2 is the same as N 1 , the ratio used in interpolators 22 , so that the output sample rate of predistortion circuitry 21 is reduced to be the same as the input sample rate. The output samples are converted to analog form by digital/analog converters (DACs) 30 and filtered by analog low-pass filters 31 . The reduced output sample rate allows output circuits of predistortion circuitry 21 to be simplified, and similarly reduces substantially the sample rate at which the DACs must operate. In this respect, the present invention differs substantively from digital predistortion schemes known in the art, such as that described in U.S. Pat. No. 4,700,151, in which the full, interpolated sample rate used in predistorting the signals is maintained, and very fast digital/analog conversion is required. Alternatively, it is possible, and sometimes desirable, to use an interpolation ratio N 1 which is different from the decimation ratio N 2 . Having a large interpolation ratio and lower decimation ratio, for example, enables predistortion circuitry 21 to suppress some out-of-band distortion products in addition to the in-band products. The interpolation and decimation ratios may be fixed or variable according to the implementation. The predistorted analog baseband signals output by filters 31 are upconverted to the desired radio frequency by an I/Q modulator 32 , which is driven by a local oscillator. The modulated signals are then amplified by power amplifier 34 . On account of the predistortion effected by circuitry 21 , the output of amplifier 34 is largely free of intermodulation distortion products in and near the frequency band of the modulated signals themselves. Amplifier 34 may also generate distortion products farther outside the signal frequency band, which are not affected by circuitry 21 on account of the limited output sample rate of the circuitry. These out-of-band products are substantially suppressed by a bandpass filter 36 following the amplifier. Reference is now made to FIGS. 2A-2F, which are spectral graphs that schematically illustrate frequency-domain operation of circuitry 21 . In a preferred embodiment of the present invention, the baseband signals input to the circuitry cover a spectral band 40 of 25 MHz (±12.5 MHz), as is typical in cellular systems. The signals are sampled at a rate of 62.5 Msps (million samples per second), so that the Nyquist bandwidth of the complex, sampled signals is 31.25 MHz, giving a “Nyquist zone” of ±31.25 MHz as shown in FIG. 2 A. FIG. 2B shows the spectrum of the samples following up-sampling in interpolators 22 , wherein a value of N 1 =4 is taken. The Nyquist zone now expands to ±125 MHz due to the up-sampling, and a comb of signal replicas 42 is formed alongside band 40 . Low-pass filters 23 remove the undesired replicas, but leave band 40 in the expanded Nyquist zone, as shown in FIG. 2 C. The effect of nonlinear corrector 24 is to generate a broad predistortion band 44 which is generally inverse to the nonlinear distortion of the power amplifier. The wings of band 44 typically extend well beyond the ±31.25 MHz Nyquist zone of the input signals. Therefore, if the predistortion were imposed without first up-sampling and interpolating the signals, the signals would be irretrievably distorted by aliasing effects. After the nonlinear correction has been applied by corrector 24 , however, it is possible to low-pass filter the predistorted signal, as illustrated in FIG. 2 E. Thus, most of the out-of-band portion of signal 44 is removed, except for a portion overlapping with or adjacent to the frequencies of band 40 . The effect of decimators 28 is then to reduce the sampling rate, i.e., to narrow the Nyquist zone back down to ±31.25 MHz, as shown in FIG. 2 F. DACs 30 can thus operate at 62.5 Msps, which is a rate can be achieved by inexpensive, commonly-available commercial components. FIGS. 3A-3D schematically illustrate spectra of analog signals in apparatus 20 , following the digital correction applied by circuitry 21 . FIG. 3A shows the spectrum of the signals following D/A conversion by DACs 30 and upconversion to a carrier frequency f c by modulator 32 . For comparison, FIG. 3B shows the spectrum of amplified signals that would be produced by power amplifier 34 in the absence of predistortion. A broad distortion band 46 is superimposed on signal band 40 . Addition of predistortion band 44 to distortion band 46 , however, removes the distortion in a cancellation region 48 that includes band 40 and adjacent frequencies, as illustrated in FIG. 3 C. Finally, the remainder of the wings of band 46 are suppressed by bandpass filter 36 , leaving only minimal out-of-band distortion 50 , without substantially affecting the amplified signal in band 40 . Apparatus 20 thus achieves linearization of output signals comparable to or better than that of digital predistortion systems operating at the full, up-sampled bandwidth throughout. FIG. 4 is a block diagram that schematically illustrates nonlinear corrector 24 , in accordance with a preferred embodiment of the present invention. Each pair of I and Q samples provided by interpolators 22 is evaluated to determine the instantaneous signal power by an absolute value block 52 . The power determination is used to select a pair of appropriate correction coefficients from a look-up table (LUT) 54 . Both the I and Q samples are multiplied by their respective coefficients in multipliers 56 to provide corrected I and Q outputs to low-pass filter 26 . The entries in LUT 54 are preferably calculated and updated based on feedback sample 38 , as noted hereinabove, and any suitable method known in the art may be used for calculating the coefficients. FIG. 5 is a block diagram that schematically illustrates details of digital predistortion circuitry 21 , in accordance with another preferred embodiment of the present invention. In this case, corrector 24 includes two parallel digital predistorters 58 , each typically comprising a power evaluator and coefficient multipliers as in the corrector circuit of FIG. 4 . The two predistorters preferably share a common LUT 60 . Interpolator 22 (shown here for simplicity as a single block, including the function of low-pass filters 23 , instead of the group of blocks in FIG. 1) up-samples the I and Q inputs, so that the input sample rate to corrector 24 is 125 Msps (equivalent to a complex bandwidth of ±62.5 MHz). The samples are multiplexed between the two predistorters 58 , so that each predistorter need operate only at 62.5 Msps (31.25 Msps×2). The parallel architecture of the circuitry shown in FIG. 5 thus alleviates the need for costly, high-speed digital components. FIG. 6 is a block diagram that schematically illustrates details of circuitry 21 , in accordance with yet another preferred embodiment of the present invention. Here interpolator 22 up-samples the signals by four, to a 250 Msps rate. The samples are multiplexed among four parallel predistorters 62 , each operating at 62.5 Msps. It will thus be observed that the parallel processing architecture of corrector 24 may be adapted to operate at substantially any desired sample rate. Although certain circuit configurations are shown in the figures and described hereinabove by way of illustration, those skilled in the art will understand that the principles of the present invention may be applied using a wide range of different circuit designs, all of which are considered to be within the scope of the present invention. Predistortion circuits based on the present invention may operate in the digital or analog domain, on real or complex (Cartesian or polar) signals, and on baseband or IF signals. They may be integrated with a variety of different amplifier types and linearization architectures and used in different system applications. It will thus be appreciated that the preferred embodiments described above are cited by way of example, and the full scope of the invention is limited only by the claims.

Linearization circuitry for predistortion of an input signal to an amplifier having a given distortion characteristic, including a correction circuit, which receives a stream of samples of the input signal at a high sample rate and which applies a correction to the samples responsive to the given distortion characteristic. The corrected samples are preferably low-pass filtered. A decimation circuit receives the corrected samples from the correction circuit and reduces the sample rate of the stream for output to the amplifier, to a reduced rate substantially less than the high sample rate. The present invention enables significant parts of the circuitry to operate at much lower sample rates that previously achievable and lends itself naturally to parallel implementations.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switch driver circuitry for use, for example, in digital-to-analog converters. 2. Description of the Related Art FIG. 1 of the accompanying drawings shows parts of a previously-considered current-switched digital-to-analog converter (DAC) 1 . The DAC 1 is designed to convert an n-bit digital input word into a corresponding analog output signal. The DAC 1 includes a plurality of individual binary-weighted current sources 2 1 to 2 n corresponding respectively to the n bits of the digital input word applied to the DAC. Each current source passes a substantially constant current, the current values passed by the different current sources being binary-weighted such that the current source 2 1 corresponding to a least-significant-bit of the digital input word passes a current I, the current source 2 2 corresponding to the next-least-significant-bit of the digital input word passes a current 2 I, and so on for each successive current source of the converter. The DAC 1 further includes a plurality of differential switching circuits 4 1 to 4 n corresponding respectively to the n current sources 2 1 to 2 n . Each differential switching circuit 4 is connected to its corresponding current source 2 and switches the current produced by the current source either to a first terminal connected to a first connection line A of the converter or a second terminal connected to a second connection line B of the converter. The differential switching circuit receives one bit of the digital input word (for example the differential switching circuit 4 1 receives the least-significant-bit of the input word) and selects either its first terminal or its second terminal in accordance with the value of the bit concerned. A first output current I A of the DAC is the sum of the respective currents delivered to the differential-switching-circuit first terminals, and a second output current I B of the DAC is the sum of the respective currents delivered to the differential-switching-circuit second terminals. The analog output signal is the voltage difference V A -V B between a voltage V A produced by sinking the first output current I A of the DAC 1 into a resistance R and a voltage V B produced by sinking the second output current I B of the converter into another resistance R. FIG. 2 shows a previously-considered form of differential switching circuit suitable for use in a digital-to-analog-converter such as the FIG. 1 converter. This differential switching circuit 4 comprises first and second PMOS field effect transistors (FETs) S 1 and S 2 . The respective sources of the transistors S 1 and S 2 are connected to a common node TAIL to which a corresponding current source ( 2 1 to 2 n in FIG. 1) is connected. The respective drains of the transistors S 1 and S 2 are connected to respective first and second output nodes OUTA and OUTB of the circuit which correspond respectively to the first and second terminals of each of the FIG. 1 differential switching circuits. Each transistor S 1 and S 2 has a corresponding driver circuit 6 1 or 6 2 connected to its gate. Complementary input signals IN and INB are applied respectively to the inputs of the driver circuits 6 1 and 6 2 . Each driver circuit buffers and inverts its received input signal IN or INB to produce a switching signal SW 1 or SW 2 for its associated transistor S 1 or S 2 such that, in the steady-state condition, one of the transistors S 1 and S 2 is on and the other is off. For example, as indicated in FIG. 2 itself, when the input signal IN has the high level (H) and the input signal INB has the low level (L), the switching signal SW 1 (gate drive voltage) for the transistor S 1 is at the low level L, causing that transistor to be ON, whereas the switching signal SW 2 (gate drive voltage) for the transistor S 2 is at the high level H, causing that transistor to be OFF. Thus, in this condition, all of the input current flowing into the common node TAIL is passed to the output node OUTA and no current passes to the output node OUTB. When it is desired to change the state of the circuit 4 of FIG. 2 so that the transistor S 1 is OFF and the transistor S 2 is ON, complementary changes are made simultaneously in the input signals IN and INB such that the input signal IN changes from H to L at the same time as the input signal INB changes from L to H. As a result of these complementary changes, it is expected that the transistors S 1 and S 2 will switch symmetrically, that is that the transistor S 1 will turn OFF at exactly the same moment that the transistor S 2 turns ON. However, in practice there is inevitably some asymmetry in the turn-ON and turn-OFF speeds. This can result in a momentary glitch at the common node TAIL which may in turn cause glitches at one or both output nodes of the circuit, producing a momentary error in the DAC analog output value until all of the switches have switched completely. These glitches in the analog output signal may be code-dependent and result in harmonic distortion or even non-harmonic spurs in the output spectrum. As the size of the glitch associated with the switching of the differential switching circuit is dependent on the symmetry of the complementary changes in the input signals IN and INB, much attention has been directed to generating and delivering these input signals to the differential switching circuit synchronously with one another. However, it is found in practice that, even if the input signals are perfectly symmetrical, the drive circuits 6 1 and 6 2 which derive the switching signals from the input signals inevitably introduce asymmetry into the switching signals SW 1 and SW 2 which actually control the transistors S 1 and S 2 . Such asymmetry results in transient output current distortion in any individual differential switch circuit. Furthermore, in a DAC employing multiple differential switch circuits, it also results in a variation between the switching times of the different circuits. These variations lower the spurious-free dynamic range (SFDR) of the DAC (a measure of the difference, in dB, between the rms amplitude of the output signal and the peak spurious signal over the specified bandwidth). These variations also lead to code-dependency of the analog output signal of the converter. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; and switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities. Such switch driver circuitry can provide improved symmetry of operation. According to a second aspect of the present invention there is provided a switch circuit comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; and a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state. According to a third aspect of the present invention there is provided a digital-to-analog converter comprising switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; the digital-to-analog converter further comprising: a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state, said first switch element being connected between first and second converter nodes and said second switch element being connected between said first node and a third converter node; and a current source or current sink connected operatively to said first converter node for causing a substantially constant current to pass through said first converter node when the converter is in use. According to a fourth aspect of the present invention there is provided a digital-to-analog converter comprising: a plurality of differential switching circuits, each differential switching circuit having switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; each said differential switching circuit further having: a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state, said first switch element being connected between first and second nodes of the differential switching circuit and said second switch element being connected between said first node and a third node of the differential switching circuit; and the respective second nodes of the differential switching circuits of said plurality being connected together, and the respective third nodes of the differential switching circuits of said plurality being connected together; and the digital-to-analog converter further comprising a plurality of current sources or current sinks, corresponding respectively to the differential switching circuits of said plurality, each current source or current sink being connected operatively to said first node of its said corresponding differential switching circuit for causing a substantially constant current to flow therethrough when the converter is in use. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, discussed hereinbefore, shows parts of a previously-considered current-switched DAC; FIG. 2 shows parts of previously-considered switch driver circuitry in the FIG. 1 DAC; FIG. 3 shows parts of switch driver circuitry according to a first embodiment of the present invention; FIG. 4 shows an example of current switching circuitry to which the FIG. 3 embodiment can be connected; FIGS. 5 (A) to 5 (D) show operating waveforms generated by the FIG. 3 embodiment when in use; FIGS. 6 (A) and 6 (B) are diagrams for use respectively in explaining operation of the FIG. 3 embodiments in first and second different states; FIG. 7 shows a graph for use in explaining a current-voltage characteristic of a circuit element in the FIG. 3 embodiment; FIG. 8 shows a modification which can be applied to embodiments of the invention; and FIG. 9 shows parts of switch driver circuitry according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows parts of switch driver circuitry according to a preferred embodiment of the present invention. The circuitry 10 includes respective first and second inverting input buffers 12 and 14 . The first input buffer receives at an input thereof a first input signal IN and the second input buffer 14 receives at an input thereof a second input signal INB complementary to the first input signal IN. The first input buffer 12 inverts the received IN signal to produce at an output thereof an inverted signal INVB. Similarly, the second input buffer 14 inverts the received INB signal to produce at an output thereof an inverted signal INV. The signals IN, INB, INV and INVB are all logic signals which change between a high logic level (H) and a low logic level (L). The inverted signal INVB is supplied from the output of the first input buffer 12 to an input of a first inverting output buffer 16 . As shown in FIG. 3, the output buffer 16 includes respective PMOS FET and NMOS FET transistors 18 and 20 . The PMOS FET transistor 18 has its source connected to a first common node CN 1 of the circuitry, its gate connected to the output of the first input buffer 12 and its drain connected to a first output node ON 1 of the circuitry. The NMOS FET 20 has its source connected to the first output node ON 1 , its gate connected to the output of the first input buffer 12 , and its drain connected to a second common node CN 2 of the circuitry. The circuitry also includes a second inverting output buffer 22 which, like the first output buffer 16 , has respective series-connected PMOS FET and NMOS FET transistors 24 and 26 . The PMOS FET 24 has its source connected to the first common node CN 1 , its gate connected to the output of the second input buffer 14 , and its drain connected to a second output node ON 2 of the circuitry. The NMOS FET 26 has its source connected to the second output node ON 2 , its gate connected to the output of the second input buffer 14 , and its drain connected to the second common node CN 2 . Connected between a positive supply line ANALOG VDD and the first common node CN 1 of the circuitry are a constant current source transistor 28 and a cascode transistor 30 . Each of the transistors 28 and 30 is a PMOS FET. The constant current source transistor 28 has its gate connected to a first biassing line B 1 of the circuitry which, in use of the circuitry, is maintained at a potential V pcs that is fixed relative to the potential of the positive supply line ANALOG VDD. The cascode transistor 30 has its gate connected to a second biassing line B 2 of the circuitry which, in use of the circuitry, is maintained a potential V pcasc which is also fixed in relation to ANALOG VDD potential. Connected between the second common node CN 2 of the circuitry and a ground potential supply line GND of the circuitry are series-connected first and second resistors R 1 and R 2 and, in parallel with the resistors, a capacitor C 1 . The resistors R 1 and R 2 have a total resistance of approximately 5 kΩ in this embodiment, with a 1:2 resistance ratio. The capacitor C 1 has a capacitance of, for example, 100 fF in this embodiment. Connected between the first and second output nodes ON 1 and ON 2 of the circuitry 10 is a further PMOS FET 32 . The PMOS FET 32 has first and second current-path terminals connected respectively to the first and second output nodes ON 1 and ON 2 . One of the first and second current-path terminals is the source of the FET and the other of the current-path terminals is the drain of the FET, the source and drain designations being dependent on the in-use potentials of the output nodes. Following convention, the higher-potential current-path terminal for a PMOS FET is designated the source, and the lower-potential current-path terminal is designated the drain. As will be explained hereinafter, these designations are swapped around in use of the circuitry. The gate of the transistor 32 is connected to a junction node JN between the first and second resistors R 1 and R 2 . As shown in FIG. 4, the FIG. 3 circuitry may be used to drive current switching circuitry of the same kind as described already with reference to FIG. 2 . Accordingly, a description of the current switching circuitry is not repeated here. The first main switching transistor S 1 in FIG. 4 has its gate connected to the first output node ON 1 of the FIG. 3 switch driver circuitry, and the second main switching transistor S 2 in FIG. 4 has its gate connected to the second output terminal ON 2 of the FIG. 3 switch driver circuitry. As indicated by the parts shown with dotted lines in FIG. 4, each branch of the current switching circuitry preferably includes a cascode transistor 42 or 44 connected between the main switching transistor S 1 or S 2 of the branch and the output terminal OUTA or OUTB of the branch. These optional cascode transistors are described more fully in our co-pending U.S. patent application Ser. No. 09/634,588 (corresponding to United Kingdom patent application no. 9926653.8), the entire content of which is incorporated herein by reference. The cascode transistor 42 or 44 in each branch has its source connected to the drain of the main switching transistor S 1 or S 2 of the branch concerned, its gate connected to the ground potential supply line GND, and its drain connected to the output terminal OUTA or OUTB of the branch concerned. Operation of the FIG. 3 and FIG. 4 circuitry will now be described with reference to FIGS. 5 (A) to 5 (D) and 6 (A) and 6 (B). Incidentally, to make the timing relationships between the various signals easier to see in FIGS. 5 (A) to 5 (D), FIG. 5 (B) is repeated as FIG. 5 (C). Initially, i.e. prior to time A in FIGS. 5 (A) to 5 (D), the first input signal IN has the low logic level L, and the second input signal INB has the high logic level H. This means that the inverted signals INVB and INB are H and L respectively. In this condition, as shown in FIG. 6 (A), in the first output buffer 16 the PMOS FET 18 is OFF and the NMOS FET 20 is ON. In the second output buffer 22 , the PMOS FET 24 is ON and the NMOS FET 26 is OFF. The constant current source transistor 28 supplies a substantially constant current I from the positive supply line ANALOG VDD to the first common node CN 1 . The current I is, for example, 150 μA. The current I passes through the cascode transistor 30 which serves to shield the drain of the current source transistor 28 from voltage fluctuations caused by fluctuations in the potential of the first common node CN 1 arising in use of the circuitry. Thus, the current I supplied to the first common node CN 1 has a first path P 1 between the first and second common nodes, as shown in FIG. 6 (A). This path passes (in order) through the channel of the PMOS FET 24 , the second output node ON 2 , the channel of the PMOS FET 32 , the first output node ON 1 , and the channel of the NMOS FET 20 . From the second common node CN 2 , the current I then passes through the resistor R 1 , the junction node JN and the second resistor R 2 , to reach the ground potential reference line GND. The potentials generated at the various circuitry nodes in this condition are as follows (see FIG. 5 (B)). The potential V JN of the junction node JN is determined by the product I.R 2 of the current I and the resistance of the second resistor R 2 which, in this embodiment, is approximately 0.36V. Similarly, the potential V CN2 of the second common node CN 2 is determined by I(R 1 +R 2 ) which, in this embodiment, is approximately 0.55V. The potential V ON1 of the first output node ON 1 is determined by the sum of the drain potential of the NMOS FET 20 and the on-state drain-source voltage of the NMOS FET 20 , i.e. V ON1 =V CN2 +V DS(ON)20 . In this embodiment, V DS(ON)20 is approximately 50 mV, so that V ON1 is approximately 0.60V. The current I flows through the PMOS FET 32 from the second output node ON 2 to the first output node ON 1 . This means that the source of the transistor 32 (i.e. its higher-potential current-path terminal) is connected to the second output node ON 2 , and its drain is connected to the first output node ON 1 . The current I flowing through the transistor 32 is set high enough to place the transistor 32 in a saturated operating region. In this case, the gate-source voltage V GS32 of the transistor 32 has an unique value determined by the current density in the transistor 32 , i.e. V GS32 =V TP −(I/k), where I is the current flowing through the transistor 32 and V TP and k are parameters of the transistor 32 determined by its physical structure. For example, V GS32 is approximately −0.9V in this embodiment. To obtain the source potential of the transistor 32 it is necessary to subtract this gate-source voltage V GS32 from the gate voltage of the transistor 32 . This source potential of the transistor 32 determines the potential V ON2 of the second output node. Thus, V ON2 =V JN −V GS32 . In this embodiment, with V JN ≈0.36V and V GS32 ≈−0.90V, V ON2 is approximately equal to 1.25V. The potential V CN1 of the first common node CN 1 is determined by the source potential of the PMOS FET 24 . This source potential is in turn determined by the drain potential of the PMOS FET 24 , i.e. V ON1 , and the ON-state drain-source voltage V DS(ON)24 of the PMOS FET 24 . Thus, V CN1 =V ON2 −V DS(ON)24 . Typically, V DS(ON)24 is approximately −150 mV, so that V CN1 is approximately equal to 1.40V in this embodiment. In this condition (FIG. 6 (A)) the first output node ON 1 has a predetermined ON output potential V on of the circuitry, and the second output node ON 2 has a predetermined OFF output potential V OFF of the circuitry, i.e. V ON1 =V on and V ON2 =V off . In this embodiment, V on ≈0.60V and V off ≈1.25V. When these potentials are applied to the switching transistors S 1 and S 2 in the current switching circuitry, the transistor S 1 , which receives the ON output potential V on , is turned ON, and the switching transistor S 2 , which receives the OFF output potential V off , is turned OFF. As a result, the potential difference V B −V A between the output terminals OUTB and OUTA is negative, as shown in FIG. 5 (D). Incidentally, the other potential differences V CASCB −V CASCA and V B ′−V A ′ shown in FIG. 5 (D) are internal signals within the current switching circuitry and will not be discussed further here. At time A in FIGS. 5 (A) to 5 (D) the first and second input signals IN and INB undergo respective complementary logic level changes (L to H for IN, and H to L for INB). In response to these changes the input buffer output signals INV and INVB also undergo complementary logic level changes (L to H for INV and H to L for INVB). As a result, as shown in FIG. 6 (B), a second current path P 2 between the common nodes CN 1 and CN 2 is created, different from the first current path P 1 shown in FIG. 6 (A). In this case, the current I supplied to the first common node CN 1 by the constant current source transistor 28 flows through the channel of the PMOS FET 18 in the first output buffer 16 , the first output node ON 1 , the PMOS FET 32 , the second output node ON 2 the and channel of the NMOS FET 26 in the second output buffer 22 . As in FIG. 6 (A), from the second common node CN 2 the current flows through the resistor R 1 , the junction node JN and the second resistor R 2 , before reaching the ground potential supply line GND. After switching has taken place, it will be appreciated that the potentials V CN1 and V CN2 of the common nodes are substantially unchanged from those prevailing before the switching took place, i.e. the potentials of the common nodes are the same in FIGS. 6 (A) and 6 (B). This is because the same current I flows through the second current path P 2 in FIG. 6 (B) as flows through the first current path P 1 in FIG. 6 (A). Also, substantially the same ON and OFF output potentials V on and V off are generated in FIG. 6 (B) as were generated in FIG. 6 (A). In FIG. 6 (B), however, the ON output potential V on is generated at the second output node ON 2 , and the OFF output potential is generated at the first output node ON 1 , i.e. V ON1 =V off and V ON2 =V on . It will also be appreciated that in FIG. 6 (B), the same current I flows through the transistor 32 as flowed in the FIG. 6 (A) case, but in the opposite direction, i.e. from the first output node ON 1 to the second output node ON 2 in FIG. 6 (B). The current-voltage characteristic of the transistor 32 is shown in FIG. 7 . In FIG. 7, the vertical axis represents current flowing through the transistor channel, and the horizontal axis represents the potential difference between the first and second current-path terminals (i.e. the potential difference across the transistor channel). As can be seen from FIG. 7, the I-V characteristic is perfectly symmetrical for both positive and negative values of the current flowing through the transistor, i.e. whichever direction the current is flowing. This means that the potential difference ΔV between the ON and OFF output potentials in FIGS. 6 (A) and 6 (B) is exactly the same. Furthermore, during switching, the potentials at the first and second output nodes ON 1 and ON 2 of the circuitry have the same rising and falling waveforms when switching (at time A) from the state shown in FIG. 6 (A) to the state shown in FIG. 6 (B) as when switching (at time B) from the state shown in FIG. 6 (B) to the state shown in FIG. 6 (A). This effect can clearly be seen from a comparison of the waveforms at times A and B in FIG. 5 (B). The FETs 18 , 20 , 24 and 26 in the output buffers 16 and 22 are desirably very small to provide for fast switching. As a consequence of their small sizes, they tend not to be closely matched. The implications of the mismatches in terms of both delay variation and amplitude variation of the ON and OFF potentials will now be considered. In terms of delay variation, because the FETs in the switch driver circuitry are very small the rise and fall times of the output node potentials are very fast (see FIG. 5 (B)). This means that although there will be delay mismatches between the FETs of the switch driver circuitry, the magnitude of the resulting delay variation at the output nodes is also very small. In terms of amplitude variation the PMOS FETs 18 and 24 do not influence the output potentials, and so if they are not matched there is no significant impact on the symmetry of the output potentials. The NMOS FETs 20 and 26 affect the output potentials only weakly (because although V on is influenced by V DS(ON) of the NMOS FET 20 or 26 that is on, V DS(ON) is itself small, e.g. 50 mV). The ON and OFF output potentials therefore only have a very small asymmetry due to mismatches of the transistors in the output buffers. The capacitor C 1 is a decoupling capacitor provided to make the potential V TAIL in the current switching circuitry settle as fast as possible. Referring to FIG. 5 (B) it can be seen that when switching occurs, V TAIL has a small rise. This rise is caused by the transient at the second common node CN 2 that occurs during switching. In order to make V TAIL settle as quickly as possible it is desirable to reduce the CN 2 transient. This is achieved, at the expense of a larger transient at the first common node CN 1 , by means of the capacitor C 1 coupled between CN 1 and GND. The transient on CN 1 does not affect the current switching circuitry, and is therefore insignificant. The capacitance value is preferably set to provide a time constant of around 500 ps, similar to the settling times of the internal signals of the switch driver circuitry. Thus, when the sum of R 1 and R 2 is approximately 5 kΩ, C 1 should have a capacitance of approximately 100 fF (giving a RC time constant of 500 ps). The transistor 32 also provides the following further advantages. Firstly, as it has a non-linear I-V characteristic, the voltage developed across it is relatively large even when the current flowing through the channel is relatively low, as occurs during switching (i.e. before and after the crossover of the rising and falling waveforms in FIG. 5 (B). This leads to a very fast settling time for the output node potentials after switching, because most of the switch driver current I is available for driving the output nodes rather than being wasted in the transistor 32 . For example, in FIG. 5 (B) it can be seen that the rising waveform, which is slower than the falling waveform, settles in approximately 600 ps. Thus, in the FIG. 3 switch driver circuitry, all of the internal signals settle in less than 600 ps. The effect of applying these fast-settling internal signals to the FIG. 4 current switching circuitry is illustrated in FIG. 5 (D). In FIG. 5 (D), it is assumed that the cascode transistors 42 and 44 are present. The resulting rise time of the potential difference between the output terminals OUTA and OUTB is approximately 350 ps (for the rise from 10% to 90% of full-scale value). This can provide an output bandwidth of 1 GHz, facilitating a typical sampling rate F DAC of the DAC of 1.6 G samples/s with a worst-case rate of 1 G samples/s. The second advantage is that, because the transistor 32 is a PMOS FET like the transistors in the current switching circuitry of FIG. 4, its saturation drain-source voltage V DS(SAT) varies in the same way as the drain-source saturation voltages V DS(SAT) of the transistors in the current switching circuitry. This is important, as in practice, the drain-source saturation voltage V DS(SAT) of a PMOS transistor may vary by a factor of 2 due to process and/or temperature variations. Considering the FIG. 4 current switching circuitry in more detail, at any given time, one of the main switching transistors S 1 and S 2 is OFF and the other is ON. Referring to FIG. 6 (B), for the purposes of explanation it will be assumed that the OFF transistor is the transistor S 1 and the ON transistor is the transistor S 2 . In this condition, the potential V TAIL of the sources of the transistors S 1 and S 2 is influenced by the drain-source potential of the ON transistor S 2 . When the switching transistors S 1 and S 2 have a relatively high drain-source saturation voltage V DS(SAT)S VTAIL is increased as compared to when V DS(SAT)S is low. This means that in order to maintain the OFF transistor S 1 in the OFF condition, its gate voltage, i.e. the OFF potential V OFF , must also be increased. This increase occurs automatically in the FIG. 3 switch driver circuitry because in that circuitry the difference between the OFF and ON potentials is increased when the drain-source saturation voltage V DS(SAT)32 of the transistor 32 is relatively high as compared to when that drain-source saturation voltage is relatively low. Accordingly, the OFF potential is self-regulating in the FIG. 3 switch driver circuitry. In the FIG.3 circuitry it is also desirable to make the ON output potential track V DS(SAT)32 of the switching transistors S 1 and S 2 and the cascode transistors 42 and 44 (if used) in the current switching circuitry. Considering FIG. 6 (A), and assuming the cascode transistors are present, in the branch of the current switching circuitry that is on, the ON output potential V on must be sufficient for both the cascode transistor 42 and the switching transistor S 1 to be maintained in the saturated condition, even when V DS(SAT) of each of those transistors varies. The nominal drain-source saturation voltage V DS(SAT)S of the switching transistors is, for example, 200 mV. The nominal drain-source saturation voltage V DS(SAT)C of the cascode transistors is, for example 300 mV. By setting V on to a nominal value of 0.6V the potential difference between the cascode transistor gate (GND) and the switching transistor gate (V on ) exceeds V DS(SAT)C by 1.5 times the nominal V DS(SAT)S of the switching transistor. However, as V DS(SAT)S and V DS(SAT)C can each vary by a factor of 2 with process/temperature, preferably V on should also increase when V DS(SAT)S and/or V DS(SAT)C increase. This change in V on to compensate for variations in V DS(SAT)S of the switching transistors S 1 and S 2 (and for variations in V DS(SAT)C of the cascode transistors 42 and 44 , if provided) can be achieved by making the resistances of the resistors R 1 and R 2 in the FIG. 3 circuitry variable in dependence upon V DS(SAT)S and/or V DS(SAT)C . One example of control circuitry for varying the resistances will now be described with reference to FIG. 8 . In FIG. 8 the control circuitry 60 includes a first constant current source 62 connected between a positive power supply line ANALOG VDD of the circuitry and a first node N 1 . A first PMOS FET 64 has its source connected to the node N 1 and its gate and drain connected to the ground potential supply line GND. The circuitry also includes a second PMOS FET 66 which has its source connected to the node N 1 . The gate and drain of the PMOS FET 66 are connected to a second node N 2 , and a constant current sink 68 is connected between the node N 2 and GND. The current I 1 sourced by the constant current source 62 is large compared to the current I 2 sunk by the constant current sink 68 . Also, the first PMOS FET 64 is narrow compared to the second PMOS FET 66 . For example, the width of the FET 64 is w and the width of the FET 66 is 3 w, and I 1 =4I sw and I 2 =I sw , where I sw is the current which flows through each switching transistor S 1 or S 2 when ON. The circuitry 60 further includes a high-output-resistance transconductance amplifier 70 having a first (negative) input connected to the node N 2 . A second (positive) input of the amplifier 70 is connected to a node N 3 of the circuitry. A second constant current source 72 is connected between the ANALOG VDD and the node N 3 . First and second NMOS FETs 74 and 76 are connected in series between the node N 3 and GND. The first NMOS FET 74 has its drain connected to the node N 3 , its gate connected to the output of the amplifier 70 and its source connected to the drain of the second NMOS FET 76 . The NMOS FET 76 has its gate connected to the output of the amplifier 70 and its source connected to GND. An output node N 4 of the circuitry 60 is connected to the output of the amplifier 70 . To enable the resistances of the resistors R 1 and R 2 in the switch driver circuitry to be varied, the resistors R 1 and R 2 are implemented using respective first and second series-connected NMOS FET transistors 80 and 82 . The first NMOS FET 80 has its drain connected to the second common node CN 2 of the switch driver circuitry 10 , its gate connected to the output node N 4 of the control circuitry and its source connected to the junction node JN (gate of the transistor 32 ) in the switch driver circuitry 10 . The NMOS FET 82 has its drain connected to the junction node JN, its gate connected to the output node N 4 and its source connected to GND. In this embodiment the NMOS FET 80 has the same size as the NMOS FET 74 and the NMOS FET 82 has the same size as the NMOS FET 76 . Alternatively, there may be a predetermined scaling factor between the two FETS 74 / 80 and 76 / 82 of each pair. The output node N 4 can also be connected to resistance-setting NMOS FETs in further segments of the DAC circuitry, so as to enable the control circuitry 60 to operate in common for all segments. Operation of the FIG. 8 control circuitry will now be described. The elements 62 to 68 serve to generate at the node N 2 a potential V DS(SAT)P which is a measure of the drain-source saturation voltage of the switching transistors in the current switching circuitry (FIG. 3 ). Because of the difference in currents flowing through the FETs 64 and 66 , and their different widths, the ratio of the current densities in the FETs 64 and 66 is 9:1 (=(I 1 -I 2 )/w:I 2 /3 w). Because V DS(SAT) is proportional to the square root of current density, the ratio between the respective V DS(SAT) s of the FETs 64 and 66 is 3:1. The respective V T s of the FETs 64 and 66 are substantially the same. The potential at node N 1 becomes equal to V DS(SAT)64 +V T64 , where the drain-source saturation voltage V DS(SAT)64 of the FET 64 is e.g. 0.9V and the threshold voltage V T64 of the FET 64 is e.g. 1V. Thus, the potential V N1 of node N 1 is, for example, 1.9V. The voltage drop across the FET 66 is V DS(SAT)66 +V T66 , where V DS(SAT)66 is e.g. 0.3V and V T66 is e.g. 1V, i.e. 1.3V. Thus, the potential at node N 2 is approximately equal to V DS(SAT)64 −V DS(SAT)66 , and this potential is taken as the measure V DS(SAT)P of drain-source saturation voltages of the switching and cascode transistors in the current switching circuitry. Incidentally, because the measure V DS(SAT)P is derived from the difference V DS(SAT)64 −V DS(SAT)66 between the respective V DS(SAT) s of two FETs 64 and 66 , it is possible that it will not accurately reflect the actual V DS(SAT) s of the FETs of interest in the current switching circuitry, i.e. the switching transistors and the cascode transistors (if used). However, if it is expected that the actual V DS(SAT) s of the FETs of interest will be, say, 0.6V in total, then it is preferable to set the conditions of the FETs 64 and 66 so that their respective V DS(SAT) s are offset equally on either side of that total actual V DS(SAT) , which is why in this example V DS(SAT)64 is set to 0.9V and V DS(SAT)66 is set to 0.3V. The second constant current source 72 sources a current I 3 that in this embodiment is substantially equal to the current I sourced by the constant current source 24 in the switch driver circuitry of FIG. 3 . In this embodiment the NMOS FET 74 has the same (variable) resistance as the NMOS FET 80 is to provide the first resistor R 1 . Similarly, the second NMOS FET 76 has the same (variable) resistance as the NMOS FET 82 used to provide the resistor R 2 . This means that the voltage at the node N 3 is the same as the voltage V CN2 at the second common node CN 2 in the switch driver circuitry. The effect of the amplifier 70 , therefore, is to adjust the potential at the output node N 4 until the potential at the node N 3 is equal to the potential V DS(SAT)P of the node N 2 . Changing the N 4 -node potential changes the potential at the node N 3 because the N 4 -node potential determines the respective resistances of the first and second NMOS FET transistors 74 and 76 in the control circuitry. In this way, in this embodiment the potential V CN2 of the second common node CN 2 is set substantially equal to the measure V DS(SAT)P . It will be appreciated that, in the FIG. 8 circuitry, the resistances of the resistors R 1 and R 2 (provided by the NMOS FETs 80 and 82 ) each vary in accordance with the potential at the node N 4 . Accordingly, as V CN2 is varied the potential variation at the junction node JN tracks the potential variation of the second common node CN 2 so as to maintain the gate potential of the transistor 32 as a substantially fixed proportion (e.g. ⅔) of the potential V CN2 . The advantage of using the FIG. 8 control circuitry to adjust the potential of the second common node CN 2 is that the ON output potential V on tracks V DS(SAT) variations of the main switching transistors and (if used) the cascode transistors in the current switching circuitry. The PMOS FET 32 serves automatically to cause V OFF to track V DS(SAT) . It will also be appreciated that in place of the PMOS FET 32 in the FIG. 3 embodiment, other circuit elements can be connected between the first and second output nodes ON 1 and ON 2 of the circuitry to achieve the same basic current-voltage conversion effect. In each case, it is preferable that the circuit element used has the same I-V characteristic irrespective of the direction of current flow through the element concerned. The I-V characteristic of the circuit element is preferably non-linear so as to provide a higher resistance at low values of current and a lower resistance at high values of current, but a linear circuit element such as an ohmic resistance element could be used. A second embodiment of the present invention, using an ohmic resistance element between the first and second output nodes, will now be described with reference to FIG. 9 . In FIG. 9, components that are the same as, or correspond closely to, components in the first embodiment of FIG. 3 have been denoted by the same reference numerals and an explanation thereof is omitted. In the FIG. 9 embodiment, in place of the transistor 32 , a resistor 102 is connected between the first and second output nodes ON 1 and ON 2 . A further resistor 104 is connected between ANALOG VDD and the source of the constant current source transistor 28 . Also, a further resistor 106 is connected between the second common node CN 2 and GND in place of the series-connected resistors R 1 and R 2 in the first embodiment. Each of the resistors 102 , 104 and 106 is an ohmic resistance element, for example a high-resistance n-diffusion resistor. As in the first embodiment, the same current I that is sourced by the constant current source transistor 28 flows selectively either along a first current path P 1 , or along a second current path P 2 , through the circuitry, in dependence upon the state of the complementary input signals IN and INB. As in the first embodiment, the potential V CN2 of the second common node is determined by the product of the current I and the resistance R 106 of the resistor 106 . In the second embodiment, the potential difference ΔV between the potentials of the first and second output nodes V ON1 and V ON2 is determined by the product of the current I and the resistance R 102 of the resistor 102 . The I-V characteristic of the resistor 102 is the same for both directions of current flow through it, so the potential difference ΔV is the same whichever state the circuitry is in (in the steady-state) The resistor 104 is provided to cause the potential V S28 of the source of the current source transistor 28 to track changes in the resistance of the resistor 102 . Within the circuitry, the resistors 102 and 104 are preferably placed physically close to one another so that their resistances will have a substantially fixed ratio irrespective of variations in their resistances brought about by process and/or temperature variations. Such variations may exhibit “gradients” across the device in one or more directions as the segments are laid out in a certain pattern over the device substrate. The make the layout within each segment insensitive to such gradients (at least in one direction) the resistor 104 may be divided into 2 equally-sized portions on opposite sides respectively of the resistor 102 . This means that the resistor 104 has a common centroid with the resistor 102 . Then, if the resistance of the resistor 102 in a segment has an increased value, so will the resistance of the resistor 104 of that segment. This has the effect of lowering the potential V S28 at the source of the constant current source transistor 28 so that, assuming its gate potential V pcs remains unchanged (relative to ANALOG VDD), its gate-source voltage is made less negative, thereby reducing the current I. In this way, the product I.R 102 , which defines ΔV, is left substantially unchanged despite the increase in R 102 . The ratios of the resistances R 102 , R 104 and R 106 are, for example, 1:2:1, with I being approximately 80 μA and R 102 being approximately 7.5 kΩ. This provides a potential difference ΔV between the ON and OFF output potentials of approximately 0.6V. When a resistance element such as the element 102 is used as the current-voltage conversion element it is not essential to use the matching resistance element 104 or, indeed, to carry out any compensation for resistance variation. In this respect, although the potential difference ΔV generated across the resistor 102 is kept substantially fixed by using such compensation, inevitably the change in current affects the circuitry in other ways and, for example, changes the speed of the switching operation of the segment. This may make it preferable to leave the current unchanged in response to resistance variations. Comparing FIG. 4 with FIG. 9, a further advantage of the FIG. 4 circuitry over the FIG. 9 circuitry is that the resistance element 102 (and the compensating resistor 104 if used) is large physically compared to the PMOS FET 32 , because a suitably large resistance (e.g. 7.5 kΩ) can only be achieved with a large physical structure (HN resistors may have a resistance of 1 kΩ/square). Such large structures have an appreciable parasitic capacitance. Also, when resistances are used, scaling of the circuitry becomes difficult since, if (say) the current is halved, the resistances must be doubled to achieve the same voltage, whereas with the PMOS FET 32 the voltage across it is maintained when the transistor is halved in size. Even worse, when the resistance is doubled, parasitic capacitance is also doubled, so that compared to the half-size transistors the parasitic capacitance goes up by a factor of 4. This makes the PMOS FET 32 far more preferable to use as the current-voltage conversion element. Although the use of a circuit element having the same I-V characteristic for both directions of current flow between the output nodes is preferable, it will be appreciated that, by using two closely-matched uni-directional circuit elements connected in parallel between the two output nodes, substantially the same effect can be achieved. For example, back-to-back diode elements could be employed between the two output nodes. Each diode could be implemented using an MOS transistor with its gate connected to its source. Although the foregoing embodiments have employed p-channel switching transistors, it will be appreciated that the present invention can be applied in other embodiments to current switching circuitry employing n-channel switching transistors (and a current sink in place of the current source). In this case, the polarities of the supply lines and the conductivity types of the transistors in the switch driver circuitry are reversed. Furthermore, although the present invention has been described in relation to DACs, it will be understood by those skilled in the art that the present invention is applicable to any type of circuitry that includes switch elements that need to switch in complementary manner with accurately-controlled complementary switching signals.

Switch driver circuity having first and second output nodes with a current-voltage converter connected therebetween and providing current paths of first and second directions between the nodes, switching circuity connected therewith being switchable between first and second states respectively permitting current flow of a common preselected magnitude in respective first and second opposite directions producing potential differences between the first and second output nodes of a common magnitude but respective, opposite polarities.

BACKGROUND OF THE INVENTION 1. Technical Field This invention relates generally to a method and apparatus for molding wall units, and in particular to constructing a wall unit having layered discrete veneer components, such as stones, on the outer surface. 2. Background Art Various methods of forming a stone veneer on a single side of a wall unit have heretofore been performed. In one of the related art techniques, a plurality of stones are arranged face-down, forming a single horizontal layer, upon a base surface as discussed in U.S. Pat. No. 1,856,906. The inherent disadvantage of this method is that, since it entails laying the veneer stones horizontally across the bottom of the form, it is limited to producing a stone veneer on only a single surface of the wall unit. Therefore, if a construction design calls for a wall unit having a stone veneer on more than one side, two wall units would have to be constructed separately and positioned back-to-back to produce the desired fixture. Similarly, if a design specified an end unit with a veneer on two or more sides, this would require two or more separate pours, with the attendant increase in manufacturing, shipping, and construction costs. A second related art method is to pre-cast the core with a plurality of discrete attachment anchors (e.g. slots, ties, etc.) and then create the veneer on the previously finished core using a story pole, sandwiching, or other known technique. See, for example, U.S. Pat. No. 5,761,876 to Keady. This process requires at least two separate casting steps or “pours.” Thus, there exists a need for a method which can be used to produce a stone veneer on multiple sides of a wall unit in an efficient and cost effective manner, for instance, in a single pour of concrete. There also exists a related need for a method which can produce stone veneers on multiple curved, sloped, or angled wall unit surfaces. SUMMARY OF THE INVENTION The present invention provides a method for forming a wall unit using a molding technique, comprising: operationally attaching a plurality of panels in an upright manner; arranging two or more layers of discrete veneer components adjacent one of said plurality of panels; filling said volume with a binding material; and subsequent to curing of the binding material, removing said panels. A wall unit form comprising a first surface; a second surface operatively attached to said first surface; end surfaces operatively attached to said first and second surfaces thereby forming an upright form and opposing sides; and optionally, a pocket structure operatively attached to at least one of said surfaces. It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice and for the sake of clarity, the various features of the drawings are not drawn to scale. On the contrary, the dimensions of the various features may have been arbitrarily expanded or reduced. Included in the drawings are the following figures: FIG. 1 is an end view of a wall unit form showing mounting of a pair of hinged or removable side panels and an end panel according to a preferred embodiment of the present invention; FIG. 2 is a plan view of the wall unit form of FIG. 1 according to a preferred embodiment of the present invention; FIGS. 3A, 3 B, and 3 C depict front, side and top views, respectively, of a wall unit produced according to a preferred embodiment of the present invention; FIG. 4 depicts a perspective view of a double stone-face wall unit produced according to a preferred embodiment of the present invention; FIG. 5 depicts a detail plan view of the seamless joint between two wall units according to FIG. 4; FIG. 6 depicts a plan view of a double corner end unit according to one possible embodiment of the present invention; FIG. 7 depicts a plan view of a left or right corner end unit with an integral pocket formed therein according to one possible embodiment of the present invention; FIG. 8 depicts a plan view of a left or right end unit according to one possible embodiment of the present invention; FIG. 9 depicts a plan view of a double corner end unit with nonlinear and tapered surfaces according to one possible embodiment of the present invention; and FIG. 10 depicts a perspective view of a wall unit form with extensions in place to form a base or footing according to one possible embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention generally provides a method for forming wall units, and in particular to a method for constructing a wall unit having layered discrete veneer components on the outer surface of at least one side. The present invention further discloses the wall unit form which is utilized in the novel production method disclosed herein. The term “stone” veneer is used throughout the description of the invention solely for ease of communication. There is no intent to limit the veneer material to stone. Rather, any discrete building component may be employed in the method described herein. While this invention is susceptible to embodiment in many different forms, there is shown in the drawings, and will be described in detail, a preferred embodiment of the invention. It should be understood, however, that the present disclosure is to be considered as an exemplification of the principles of this invention and is not intended to limit the invention to the embodiment illustrated. 1. The Wall Unit Form Referring to FIG. 1, this figure shows an end view of a wall unit form 10 with first and second side panels 12 , 14 and a first end panel 16 . All of these panels, and second end panel 18 (FIG. 2 ), are mounted to each other upon the ground or upon a base panel 20 , according to the present invention. The side panels 12 , 14 , as well as the first and second end panels 16 , 18 can be hinged (as shown) or removably attached. An advantage of the movable panels 12 , 14 , 16 , 18 is that they facilitate entry into the wall unit form 10 during various production operations as will be discussed in the Method section below. The wall unit form 10 may also include a cavity to accommodate material that will form a base or footing if the footing is to be molded as an integral piece of the wall unit 50 . The base or footing cavity can be formed by extensions 84 that are attached, as necessary, to movable panels 12 , 14 , 16 , 18 (FIG. 10 ). The extensions 84 may be of any required contour, and these are capable of producing a base having either squared or radiused corners and ends. The wall unit form 10 is also adaptable to receive a form liner. The form liner is operationally attached to the interior of panels 12 , 14 , 16 , 18 and facilitates the desired alignment of irregularly-shaped veneer components, in a random horizontal and vertical orientation, against the form liner. The form-liner is a smooth sheet of material such as, inter alia, wood, metal, plastic, or the like, which covers and protects the interior surface of panels 12 , 14 , 16 , or 18 , and which can be used to reduce the overall size of a finished wall unit. Thus, a single wall unit form 10 , can be combined with a variety of different size form liners, to produce different size wall units. A form liner, as herein described, is thus distinguished from the “guide form” known in the related art (See, for example, U.S. Pat. No. 1,809,504 to Carvel, FIG. 18, element 24; and FIG. 26, element 32). The guide forms of the related art are affixed to the insides of the form panels to provide regular intervals between discrete components. The base panel 20 is further adapted to receive a pocket forming structure such as a footing loop pocket structure 24 . Use of the footing loop pocket structure 24 enables formation of a shear key or footing loop pocket 48 (FIGS. 3A, 3 B) in the bottom surface of the wall unit 50 . The connecting loop pocket structure 22 (FIG. 2 ), the footing loop pocket structure 24 (FIG. 1 ), and the lifting loop pocket structure 56 (FIG. 1) are structures that are temporarily and removably placed upon the panels 12 , 14 , 16 , 18 forming the wall unit form 10 to create longitudinal voids in the finished wall unit 50 . These voids are useful for accommodating means for interlocking adjacent wall units 50 as will be discussed herein below. The loop pocket structures (connecting, footing, and lifting, 22 , 24 , 56 , respectively) may be formed on any surface of the wall unit, but are typically formed on the ends, top, or bottom of the wall unit 50 . The loop pocket structures 22 , 24 , 56 are typically vee-shaped, but they may have any another cross-sectional shape which may be more suited to a particular application. Finally, the loop pocket structures 22 , 24 may be fabricated of metal, wood, plastic, or any other material having the structural properties required by this process. As shown in FIG. 2, the wall unit form 10 can receive a connecting loop pocket structure 22 at either or both ends. The connecting loop pocket structure 22 is attached to either or both end panels 16 , 18 . Use of the connecting loop pocket structure 22 allows a connecting loop pocket 46 (FIG. 3A) to be formed on the ends 52 , 54 of the wall unit 50 . Referring now to FIG. 3, there are shown several views of a wall unit 50 . FIG. 3A presents a front view of a wall unit 50 , showing a connecting loop pocket 46 at each end of the wall unit 50 . Connecting loop rods 30 extend into the connecting loop pockets 46 from the interior of the wall unit 50 . Similarly, lifting loop rods 28 extend into the lifting loop pocket 58 , and provide a means for lifting the wall unit 50 when so required. The connecting loop rods 30 and the lifting loop rods 28 are typically formed from reinforcing rods, commonly known as rebar, of sufficient size and quantity as dictated by the application. A footing loop pocket 48 is shown formed along the bottom of the wall unit 50 . Footing loop rods 70 may be formed that extend into the footing loop pocket 48 , in mirror image fashion compared to the lifting loop rods 28 and the lifting loop pocket 58 . The footing loop rods 70 may be used to anchor the wall unit to a concrete footing 36 or other base, typically by attachment to a footing-to-unit loop rod 64 (FIG. 4 ). Also shown is a chaseway 32 which can accommodate pipes, culverts, wiring, drainage, unit lifting means, windows, doorways, or the like. The chaseway 32 may be placed at other locations within the wall unit 50 . While only a single chaseway 32 is shown, a plurality of chaseways 32 may be employed as necessary. FIG. 3B shows a side view of a wall unit 50 presenting a second view of many of the features described above. Also shown here are a plurality of the stone veneer pieces 26 . The veneer pieces 26 comprise the sides of the wall unit 50 , while the inner space between the veneers is occupied by a binding or cementation material 34 . The binding or cementation material 34 may be cement, concrete, mortar, or other suitably binding material such as certain foams and plastic compounds. FIG. 3C depicts a plan view of the wall unit 50 , which further presents the features discussed above. The wall units 50 are not limited to having a stone veneer 26 on one or two sides. They may have a stone veneer 26 on any number of sides. For instance, FIG. 6 shows a double corner end unit 72 which has a rectangular shape, and a stone veneer covering four sides. A left or right end unit 76 may also be formed (FIG. 8 ). Further, the connecting loop pocket 46 need not be placed at an end of the wall unit 50 . It may be placed on a side to yield the left or right corner end unit 74 shown in FIG. 7 . Finally, the wall unit form 10 is not limited to a rectangular shape. The sides may be angled or curved to meet any design criteria. FIG. 9 depicts a composite wall unit 78 which includes both of these features. 2. Method of Making the Wall Unit The wall unit 50 is produced using the wall unit form 10 illustrated in FIGS. 1 and 2. As a first step, hinged or removable first and second surfaces or side panels 12 , 14 are removably attached to first and second end surfaces or panels 16 , 18 . The panels 12 , 14 , 16 , and 18 may also be affixed to an optional surface base or panel 20 at this time. However, depending on the size and configuration of the wall unit 50 that is to be constructed, either end panel 16 , 18 may be left off to facilitate access to the interior of the wall unit form 10 . The wall unit form 10 may commonly have a rectangular shape, but could have any desired shape, including angled sides, curved sides, or sloped sides (FIG. 9 ). Once the desired panels are in place, removable structures may be affixed to the panels. These structures function as connecting loop pocket structures 22 , footing loop pocket structures 24 , or lifting loop pocket structures 56 , depending on their placement within the form. Next, individual stones are placed along the bottom of at least one side panel. Successive layers of stones are stacked upon the initial layer, thereby forming a stone veneer 26 . Smaller pieces of stone or non-stone material may be used as shims 82 (FIG. 3B) to ensure a specified gap or joint size between the stones. Alternatively, the stones may be stacked with no spaces between them. The stone veneer can also be built to accommodate chaseways, drainage pipes, culverts, windows, doorways, lighting fixtures, etc., as required. A stone veneer may be built against a single wall, or preferably, on more than one wall at the same time. For those units requiring that there be no visible seams between wall units 50 , removable indentation blocks 80 (FIG. 4) are placed in appropriate locations in the stone veneer 26 . Once installation of the stone veneers 26 is completed, reinforcing rods are added as necessary to provide structural integrity, and to provide lifting loop rods 28 , connecting loop rods 30 , and footing loop rods 70 . Now that the discrete components of the wall unit 50 are in place, any panels 12 , 14 , 16 , and 18 which were not installed earlier are attached to complete the form. The wall unit form 10 is then filled with a binding or cementation material 34 . This binding material 34 is poured into the wall unit form 10 through the exposed upper area. The binding material 34 may be textured or colored, and may be a mortar, cement, concrete or similar mixture, or a plastic or foam compound. The binding material 34 is then allowed to cure. In some architectural applications it will be desirable for adjacent wall units 50 to appear as if there is no joint between them. In such cases, a temporary, removable indentation block 80 is placed at any suitable location in the stone veneer 26 array prior to addition of the binding material 34 . The indentation block 80 is removed after curing, thus leaving a void in the stone veneer 26 . A seamless joint can then be accomplished using a stone crossing joint 38 (FIG. 5) which is placed across the vertical joint between the units 50 utilizing the space vacated by the removable indentation block 80 (FIG. 4 ). Similarly, horizontal joints can be disguised between stacked wall units 50 . The wall unit 50 may also be formed with a footing or base 36 , wherein the footing 36 which is poured as an integral portion of the wall unit 50 at the same time that the remainder of the wall unit 50 is poured. The foregoing specification is intended as illustrative and is not intended to be taken as limiting. Still other variations within the spirit and scope of this invention are possible and will readily present themselves to those skilled in the art.

A method of forming a wall unit having a veneer face is disclosed. Initially, a pair of side wall panels and a pair of end panels are mounted substantially upright. Stones or other suitable material are set sequentially in a horizontally disposed course using at least one of the panels. Additional courses of stones or other material may then be stacked upon the initial layer until the desired height is attained. The interior volume of the apparatus is left substantially empty, and is then filled with a binding material. The binding material binds the courses' components together and integrates the individual courses into a single cohesive unit. The wall and end panels are removed and the unit is removed for subsequent installation.

BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates in general to a distributed temperature sensing method based on the spontaneous Brillouin scattering effect, more particular, to a spectrum decomposing method to achieve high spatial resolution, high temperature resolution and long sensing range of the distributed temperature measurement. 2. Description of Related Art There are two ways to fulfill the distributed sensing approach. One includes the use of single sensors being discretely arranged along a sensing line, but will make the whole sensing system much complicated. The other one as described hereinafter includes the use of optical-fiber sensors to obtain the detecting physical parameters along a linear fiber depending upon the optical characteristics thereof. Under the circumstances, the optical fiber are regarded, on one hand, as an active component for sensing measurement and, on the other hand, as a passive component for the information transmitting material to obtain the following advantages: 1. The optical fiber is small in volume and light. Thus, the optical fiber can be adopted easily anywhere. 2. Since the frequency bandwidth of the optical fiber is large, many signals may be transmitted simultaneously. 3. Since the optical fiber is made of nonconductive insulating material, it is not influenced by external electromagnetic waves. Thus, the signal may be transmitted without noise. 4. Due to the development of optical fiber technology, optical fibers can be manufactured at a low cost. As such, the utilization of fiber-distributed sensing for the measurement of strain and/or temperature distribution is widely applied on many implementations to monitor such as tunnels, bridges, dams and airplanes, buildings and etc. for safety-secured purpose. Recently, the distributed temperature sensors (DTS's) that use Brillouin scattering as the sensing mechanism have been intensive studied. The Brillouin frequency shift is dependent on the temperature and strain conditions of the optical fiber, which provides the basis for a sensing technique capable of detecting these two parameters. In the Brillouin-based distributed temperature sensing system, if a higher spatial resolution is accomplished, the measured temperature distribution is more closed to the practical situation of the fiber. The sensing spatial resolution is defined as the 10%/90% rise times from the unheated section to the heated section of the fiber. To achieve higher spatial resolution in a Brillouin scattering system, the measurements utilizing a short-pulsewidth laser source have been reported, which are disclosed by T. Horguchi, K. Shimizu, T. Kurashima, M. Taleda, and Y Koyamada, published in J. Lightwave Technol ., 13, 1296 (1995), and A. Fellay, L. Thevenaz, M. Facchlni, M. Nikles, and P. Robert, published in Proc. OSA Tech. Dig ., 16, 324 (1997). However, owing to the Brillouin linewidth limitation, it is obvious that using the time-domain pulsed approach is unsuitable for distributed measurements of submeter spatial resolution unless other techniques are employed. More recently, several methods have been reported for performing the measurement with submeter spatial resolution. One such technique, disclosed by K. Hotate and T. Hasegawa, published in Tech. Dig. Opt. Fiber Sens ., 17, 337(1999), is the direct-frequency modulation method that demonstrated a sensing spatial resolution of 45 cm over 7.8 m sensing range, and another techniques, disclosed by M. D. DeMerchant, A. W. Brown, X. Bao, and T. W. Bremner, published in J. Lightwave Technol . 38, 2755 (1999), and A. W. Brown, M. D. DeMerchant, X. Bao, and T. W. Bremner, published in J. Lightwave Technol . 17, 1179 (1999), utilize the sensing fiber with uniform strain and identical length in each section to achieve the spatial resolution of 40 cm and even 25 cm with the enhancement of compound spectra processing method. In addition, a Brillouin-based distributed temperature sensing system that provide a spatial resolution of 35 cm and a temperature resolution of 4.3° C. over 1 km based on measuring the Landau-Placzek ratio with a pulsewidth of 3.5-ns has also been reported by H. H. Kee, G. P. Lees, and T. P. Newson, IEEE Photon, Technol. Lett ., 12, 873 (2000). However, the short-pulsewidth laser sources are requisite for these methods to accomplish measurements of submeter spatial resolution. Thus the sensing ranges of these methods are limited. SUMMARY OF THE INVENTION It is therefore, in one aspect, an object of the present invention to provide a method that can provide a distributed temperature measurement with high spatial resolution and long sensing range based on decomposing the spectra of the spontaneous Brillouin scattered signals. This method utilizes a long-pulsewidth laser source to derive the long sensing range and employs a signal processing technique of decomposing Brillouin spectrum to raise the spatial and resolutions to submeter level. According to the above-mentioned objects of the present invention, the method for distributed temperature measurement based on decomposing spectra of spontaneous Brillouin scattered signals includes: (a) supplying a laser source with an optical pulse to an optical fiber; (b) obtaining a first measured Brillouin spectrum in a reference temperature section of the optical fiber, and at least a second measured Brillouin spectrum and a third measured Brillouin spectrum in a temperature overlapped region of the optical fiber, the measured Brillouin spectra above corresponding to the optical pulse entering a fiber section of the optical fiber with a length of d at a traveling time t d for t i >t d >t 0 and a sampling interval t 1 −t 0 ; (c) determining the length of d according to the measured Brillouin spectra above and a weighting factor ranging from 0 to 1; (d) determining a real Brillouin spectrum profile of the fiber section according to the length of d, the corresponding weighting factor and the measured Brillouin spectra above; and (e) determining a temperature distribution according to Brillouin frequency shifts of the real Brillouin spectrum profile. As a result, a spontaneous Brillouin-based distributed temperature sensing system using a new Brillouin spectrum decomposing technique to achieve high spatial and position resolutions, high temperature resolution and long sensing range. For a 9500-m sensing range of standard single-mode fiber and a 100-ns pulsewidth laser source, a spatial resolution of 20 cm and a temperature resolution of 1° C. are simultaneously achieved by using this signal processing method. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become fully understood from the detailed description given herein below illustration only, and thus are not limitative of the present invention, and wherein: FIG. 1 ( a ) shows an experimental setup for a long-range sensing approach according to the present invention. FIG. 1 ( b ) shows an experimental setup for a short-range sensing approach according to the present invention. FIG. 2 shows the averaged change in Brillouin frequency shift as a function of temperature change by comparison structure in FIG. 1 ( a ). FIG. 3 shows the measured optical pulse shape and the corresponding weighting factor versus the overlap time of the optical pulse and the sensing fiber. FIG. 4 shows the positions of sensing fiber obtained by the present invention with respect to the ideal one versus the changes. FIG. 5 shows the measured and calculated results of the change in Brillouin frequency shift and the corresponding temperature along the fiber in FIG. 1 ( a ). FIG. 6 shows the measured and calculated results of the change in Brillouin frequency shift and the corresponding temperature along the fiber in FIG. 1 ( b ). DETAILED DESCRIPTION OF THE INVENTION According to the paper discloses by T. Kurashima, M. Taleda, T. Horguchi, and Y Koyamada, published in IEEE Photon, Technol. Lett ., 9, 360 (1997), the Brillouin optical-time-domain reflectormeter (BOTDR) can be used to measure the spontaneous Brillouin spectra along an optical fiber from one-end. If the temperature in a fiber section is not uniform, a compound Brilloum spectrum composed of the frequency-domain signals of two sections is observed in the overlapped area where the traveling optical pulse is crossing these two sections. Assuming that an optical pulse enters a fiber section with a length of d at the traveling time t d and the measured Brillouin spectra, A(t i ) are known for t i >t d >t 0 (t 0 =t 1 —sampling interval), the real Brillouin spectrum in this fiber section can be derived by decomposing the measured Brillouin spectra. The subscript, i, represents the sampling sequence of the returned Brillouin scattering Iightwave within this fiber section. If the real Brillouin spectrum profile of this fiber section is B, then the relationship between B and A(t 1 ) can be expressed by A ( t 0 )·(1 −W ( t i −t d ))+ B ·( W ( t i −t d ))= A ( t i ) for t i −t d <d /( c/n ),  (1) A ( t 0 )·(1 −W ( t i −t d )+ W ( t i −t d −d·n/c ))+ B ·( W ( t i −t d )− W ( t i −t d −d·n/c ))= A ( t i ) for d/(c/n)≦t i −t d ≦pulsewidth,  (2) where c is the velocity of light in a vacuum, n is refraction of index, and W(t i −t d ), ranged from 0 to 1, is a weighting factor determined by the optical pulse shape and overlap time. Thus t d , d and B can be derived from the above equations by substituting the measured profiles of compound Brillouin spectra in the overlap area. Moreover, the corresponding sensing temperature of this fiber section will be obtained from the change in the Brillouin frequency shift of B. For Example, if the temporal sampling interval of BOTDR is short enough to achieve t 2 −t d <d/(c/n), then t d according to Eq. (1), obtained implicitly by A  ( t 0 ) · [ 1 - W  ( t 2 - t d ) + W  ( t 2 - t d ) · ( 1 - W  ( t 1 - t d ) ) W  ( t 1 - t d ) + A  ( t 1 ) · W  ( t 2 - t d ) W  ( t 1 - t d ) - A  ( t 2 ) = 0 ( 3 ) In addition, Brillouin spectrum profile, B, can be given by B = A  ( t 1 ) - A  ( t 0 ) · ( 1 - W  ( t 1 - t d ) ) W  ( t 1 - t d ) ( 4 ) Consequently, the sensing temperature of this fiber section is derived from the Bnulouin frequency shift of B. Nevertheless, the sensing spatial resolution that is defined as the 10%/90% rise times from the unheated section to the heated section is independent of the used optical pulsewidth of BOTDR. As a result, a distributed temperature measurement with a high spatial resolution and a long sensing range can be accomplished by using a short sampling interval and a long-pulsewidth laser source based on this signal processing method of decomposing Brillouin spectra. FIG. 1 shows the experimental setup. A BOTDR with operating wavelength at 1554-nm is used to measure the spontaneous Brillouin spectra along the length of standard single-mode fiber (SMF). For the temperature measurement, three separate sections of the test SMF and an optical switch box are arranged as shown in FIG. 1 ( a ). The optical switch box, as shown in FIG. 1 ( a ), was composed of a pair of 1×5 optical switches and five fiber paths with lengths of 1.20, 1.72, 2.18, 2.71, and 3.18, respectively. The first 9.473-km SMF remained on the original spool as supplied by the manufacturer, the subsequent 20-m SMF is subject to a low-level tension as a reference section, and the final sensing 50-m SMF is placed in a thermally insulated oven. The operating conditions of BOTDR are as following: output power of 23 dBm, pulsewidth of 100 ns, average times of 2 15 , sweep frequency of 5 MHz, and sampling interval of 2m. FIG. 2 is a plot of the averaged change Δν B in Brillouin frequency shift as a function of temperature change (ΔT) by comparing the Brillouin frequency shift of the 50-m sensing SMF with that of the 20-m reference fiber. From these data, the temperature coefficient of the Brillouin frequency shift is determined to be 0.934 MHz/° C. for this SMF. In addition, it can be observed that the temperature resolution is less than 1° C. by using this 50-m sensing SMF. FIG. 3 shows the measured optical pulse shape under the BOTDR condition of 100-ns pulsewidth and the corresponding weighting factor, W(t i −t d ), versus the overlap time, (t i −t d ), of the optical pulse and the sensing fiber. It is obvious that the optical pulse has a rise/fall time of <5-ns and the weighting factor is presenting a linear relationship to the overlap time when the overlap time is not in the rising and falling region. To verify that the submeter position and spatial resolutions can be achieved for the temperature measurement by using this signal processing method, the condition in this experiment setup was as same as that in the above case of FIG. 1 ( a ) except that the BOTDR parameter of 1-m sampling interval is set. By switching the 1×5 optical switch pair, the changes in the position of 50-m sensing fiber with 50-cm step can be obtained. In addition, the temperature in the oven was set as 45° C. and the room temperature for reference was 22° C. Using the arrangement in FIG. 1 ( a ), the Brillouin spectra in the overlap region of reference fiber and sensing fiber are measured for different fiber paths in the optical switch box; thus, the location of 50-m sensing fiber for each case can be derived by substituting the measured results into Eq. (3). FIG. 4 shows the positions of the 50-m sensing fiber that are derived by using this Brillouin spectrum decomposing method versus the changes, ΔL, in the position of 50-m sensing fiber referred to the 1.20 m fiber path. Also from FIG. 4, it is known that the position error is within ±10 cm. To further confirm that the submeter spatial resolution is achievable, the oven temperature of 45.2 or 47.3° C. and the temperature of24° C. in reference fiber section were set. In addition, the optical switch box is removed. FIG. 5 shows the measured and calculated results of the change Brillouin frequency shift and the corresponding temperature along the fiber. The 10%/90% rise times (also defined as the spatial resolution) from the unheated section to the heated section are measured as 8 m and 8.5 m for oven temperature at 45.2 and 47.3° C., respectively. However, they can be dramatically improved to 20 cm and the corresponding temperature error are within ±0.5° C. as shown in the calculated curves. As a result, a distributed temperature measurement with 20-cm position and spatial resolutions, 1° C. temperature resolution and 9500-m sensing range can be accomplished by using this Brillouin-spectrum decomposing method under the condition of 100-ns pulsewidth laser source. To demonstrate the feasibility of this method for the sensing fiber shorter than the product of (c/n) times the optical pulsewidth, the sensing fiber of 1-m is used as shown in FIG. 1 ( b ). In the experimental setup of FIG. 1 ( b ), four separate sections of the test SMF are arranged. Moreover, these four SMF sections are the first 9.473-km SMF remained on the original spool, the subsequent 28-m SMF with low-level tension, the sensing 1-m SMF in the oven, and the final 20-m SMF with low-level tension. The BOTDR parameters are consistent with those in the above experiment. Using this signal processing method, FIG. 6 shows the measured results of the change in Brillouin frequency shift and the corresponding calculated results of temperature along the fiber for oven temperatures at 45.1 and 47.1° C. and reference fiber section at 20° C. for 1-m sensing fiber. After substituting the measured results into Eq. (3) and (4), the positions (t d ) of the 1-m sensing fiber are calculated as 9501.7 and 9501.6 m for over temperatures at 45.1 and 47.1° C., respectively. In addition, the sensing fiber lengths (d) are derived as 1.1 m for over temperature 45.1 and 47.1° C. Also from these calculations, the sensing temperature for oven temperature at 45.1 and 47.1° C. are 45.0 and 47.2° C., respectively. Consequently, the temperature measurement with spatial resolution of 20-m, temperature resolution of 1° C. and sensing range of 9500 m is retrieved by using this Brillouin-spectrum decomposing method under the condition of 100-ns pulsewidth laser source. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

A method that utilizes a short sampling interval and a long-pulsewidth laser source to obtain the long sensing range and employs a signal processing technique of decomposing Brillouin spectrum to achieve high spatial resolution, high temperature resolution of the distributed temperature measurement is disclosed. The present method includes the steps of measuring the Brillouin spectra of an optical pulse applying to a sensing fiber and a overlapped area thereof, determining the length that the pulse enters according to the measured Brillouin spectra and a weighting factor and then determining a real Brillouin spectrum profile and a temperature distribution according to Brillouin frequency shifts thereof. For a 9500-m sensing range of standard single-mode fiber and a 100-ns pulsewidth laser source, spatial and positon resolutions of 20 cm and a temperature resolution of 1° C. are simultaneously achieved by using this signal processing method.

This application is a continuation application under 37 C.F.R. §1.53(b) of prior application Ser. No. 08/771,808 filed Dec. 23, 1996, now U.S. Pat. No. 5,827,439. The disclosures of the specification, drawings and abstract of application Ser. No, 08/771,808 are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a liquid quenching method for manufacturing an amorphous metal wire or thin strip (hereinafter "thin strip") by quenching and solidifying a molten alloy on a moving cooling substrate. More particularly, the present invention relates to a method for supplying molten alloy from a ladle storing the molten alloy to a tundish. 2. Description of the Prior Art Liquid quenching methods for producing thin strips include, for example, the single roll method which discharges a molten alloy on to a single cooling roll rotating at a high speed resulting in the manufacture of a thin strip. In the twin roll method, the molten alloy is discharged between a pair of cooling rolls rotating at a high speed resulting in the manufacture of a thin strip. A liquid quenching method which uses a single roll cooling/solidification apparatus, as shown in FIG. 7, will be explained. Molten alloy 6 is poured into a tundish 5 so that the level of the molten metal becomes constant. Twyer bricks 9 are disposed on the bottom wall of this tundish 5. An intermediate nozzle 10 and a nozzle holder 11 are interconnected to a passage 13 bored in these twyer bricks 9 to provide a fluid path for the molten alloy. An expanded internal space 14 is located inside the nozzle holder 11. A nozzle chip 12 is fitted to the distal end of the nozzle holder 11, and a nozzle slit 15 is inserted inside this nozzle chip 12 for discharging molten alloy onto the chill roll 8. The expanded internal space 14 inside the nozzle holder 11, the nozzle chip 12 and the nozzle slit 15 are illustrated in FIG. 8. Here, the expanded internal space 14 represents an expanded portion of the molten metal passage 13 inside the nozzle holder 11 so as to obtain a thin strip having a large width. The nozzle slit 15 provides an opening for jetting the molten metal flowing through the nozzle chip 12. When a tundish stopper 4 is moved up, the molten alloy 6 inside the tundish 5 is allowed to flow through the molten metal passage 13 and is jetted from the nozzle slit 15 onto the cooling roll 8. At this time, the flow rate of the molten alloy 6 flowing out from the nozzle slit 15 onto the cooling roll 8 is controlled in accordance with the static pressure of the molten metal inside the tundish 5. The molten alloy 6 jetting out from the nozzle slit 15 is rapidly cooled on the surface of the cooling roll 8 and is formed into the thin strip 7. The cooling roll 8 is illustrated in a small scale compared with the large scale of the tundish 5 in FIG. 7 in order to make the entire apparatus more easily understood. In order to obtain the thin strip by either of the liquid quenching methods described above, the cooling rate must be set to at least about 10 2 K/sec. Therefore, there is a limitation on the sheet thickness of the resulting thin strip. It is as small as less than about 0.1 mm. When the thin strips having a thickness of less than 0.1 mm are produced by the liquid quenching method, there are differences in the limiting conditions of the various production factors in comparison with ordinary ingot casting methods and continuous casting methods according to conventional solidification technologies. The most important limiting condition is the feed quantity of the molten alloy. In the case of the continuous casting methods for steels, etc, that have been ordinarily employed, the quantity of the molten alloy that can be provided to a casting mold is several tons per minute. A greater quantity of molten alloy can be provided in ordinary ingot casting methods. In contrast, in the liquid quenching method which is the subject of the present invention, the feed quantity of the molten alloy must be reduced to a very small quantity of not greater than 100 kg/min. This is because of the limitation on the thickness of the thin strip. The maximum strip thickness that can be ordinarily obtained by the single roll method, for example, is about 0.1 mm. The peripheral speed of the cooling roll in this case is about 10 m/sec and the maximum width of the thin strip is about 200 mm. In the case of alloys containing iron as the principal component, the feed quantity of the molten alloy must be controlled to about 90 kg/min. When the thin strip is produced by the liquid quenching method in an industrial practice, it is a very important to minimize the feed quantity of the molten alloy. In the case of a conventional continuous casting method, for example, the molten alloy is supplied from a ladle to the casting mold through a tundish. In this instance, a system using a ladle stopper fitted to a long nozzle hole at the bottom of the ladle is employed as one of the methods of controlling the feed quantity of the molten alloy. In other words, the feed quantity of the molten alloy is controlled by moving the ladle stopper up and down, thereby controlling an opening area of the long nozzle. Since a conventional continuous casting method can supply a large quantity of the molten alloy such as several tons per minute as described above, the feed quantity can be easily controlled by such a stopper system. In contrast, in the case of the liquid quenching method, which is the object of the present invention, the feed quantity of the molten metal must be limited to not greater than 100 kg/min. Therefore, it becomes difficult to employ, as such, the stopper system described above. Japanese Unexamined Patent Publication (Kokai) No. 1-34550, for example, proposes a method which uses the stopper system in the liquid quenching method. Though this method is not limited to the production of the amorphous alloy thin strip, it is devised so as to reduce the relative feed quantity of the molten alloy. It measures the weight of the molten alloy inside the tundish during charging and controls the up or down moving speed of the ladle stopper and the ladle stopper position on the basis of this measurement so as to control the feed quantity of the molten alloy. This method limits the lower limit of the moving distance of the ladle stopper to 2 mm and the upper limit to 6 mm. It can control the feed quantity of the molten alloy with a very high level of accuracy. According to this method, however, the weight of the tundish must be measured during charging and hence, the control becomes complicated. Further, because a measuring instrument and a computer must be installed, the setup cost becomes high and thus the production cost becomes high. If the moving distance of the ladle stopper is limited to an excessively small value, the operation becomes more difficult because most installations are not free from vibrations no matter how precise they may be. Because of vibration problems, the moving distance of the ladle stopper must be at least about 5 mm. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple and economical method for supplying a molten alloy for producing a thin strip which solves the problems encountered in the feed control of the molten metal in the conventional liquid quenching method by specifying the correlation between a long nozzle and a stopper. The gist of the present invention resides in the following points. The present invention is directed to method for supplying molten alloy to a moving cooling substrate for producing an amorphous metal wire or an amorphous metal thin strip. A ladle is provided for receiving the molten alloy, with the ladle having a bottom wall defining a bottom surface of the ladle. A long nozzle is provided having a length and having an interior passage therein extending the length of the long nozzle. The length of the interior passage extends in a perpendicular direction or inclined to the perpendicular direction. The long nozzle has one end connected to the bottom wall of the ladle placing the interior passage of the long nozzle in fluid communication with the molten alloy in the ladle. A ladle stopper is provided disposed within the ladle. The ladle stopper has an outer wall surface parallel to the perpendicular direction. A tundish is provided below the ladle and in fluid communication with the long nozzle for receiving molten alloy from a distal end of the interior passage of the long nozzle. Molten alloy is supplied from the ladle to the tundish by feeding molten alloy via the interior passage of the long nozzle. Molten alloy is supplied from the tundish to the moving cooling substrate. The ladle stopper is provided with a distal end region having a length which is received by the interior passage of the long nozzle at the one end of the long nozzle. A distance (y) is defined as an overlap distance of the length of the distal end region of the ladle stopper received by the interior passage of the long nozzle during flow of the molten alloy through the interior passage. An opening area (Ao) is defined which is a sectional area for molten alloy flow provided by the opening area in the interior passage of the long nozzle resulting from receiving the distal end region of the ladle stopper. A distance (Ln) is defined as the distance from the bottom surface of the ladle to the minimum cross-sectional area of the interior passage of the long nozzle. A distance (Lm) is defined as the distance from the bottom surface of the ladle to a height of molten alloy in the ladle at start of feed of the molten alloy. When (y) is less than 0.1 mm, Ao is set to be 1.2 cm 2 and a ratio (Ln)/(Lm) is set be at least 1.5. When (y) is 0.1 to 200 mm, Ao is set to be 0.5 to 10cm 2 . In another embodiment of the present invention, feed of molten alloy is started from the ladle to the tundish by moving the ladle stopper upward a selected distance thereby placing the ladle stopper in a selected position. The ladle stopper is maintained in the selected position until feeding of the molten alloy is completed. In a further embodiment of the present invention, the distal end region of the ladle stopper is a protrusion having a length of at least 5 mm and having an outer wall surface, with the outer wall surface of the protrusion being parallel to the perpendicular direction. The interior passage of the long nozzle has an inner wall surface. The outer wall surface of the protrusion does not contact the inner wall surface of the interior passage when the protrusion is received by the interior passage. In still a further embodiment of the present invention, the distal end region of the ladle stopper is a protrusion having a length of at least 5 mm and having an outer wall surface, with the outer wall surface of the protrusion being parallel to the perpendicular direction. The interior passage of the long nozzle has an inner wall surface. A portion of the outer wall surface of the protrusion contacts the inner wall surface of the interior passage when the protrusion is received by the interior passage. In yet another embodiment of the present invention, the interior passage of the long nozzle has an inner wall surface and at least one obstacle to molten alloy flow is disposed on the inner wall surface of the interior passage. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an apparatus used for practicing the method of the present invention. FIGS. 2(a) to 2(c) are views showing an example of a ladle stopper equipped with a protrusion that is used in the method of the present invention. FIG. 3 is a schematic view showing an example of a ladle stopper and a long nozzle used in the method of the present invention. FIG. 4(a) is a schematic view and FIG. 4(b) is an enlarged schematic view showing an example of a ladle stopper equipped with a protrusion and a long nozzle used in the method of the present invention. FIGS. 5(a), 5(c) and 5(d) are sectional views taken along a line I--I of FIG. 3 and a line II--II of FIG. 4(a) showing the relationship of an overlap portion between a ladle stopper and a long nozzle used in the method of the present invention, wherein (a) and (b) show a noncontact state and (c) and (d) show a contact state, respectively. FIGS. 6(a), 6(b), 6(c), 6(d) and 6(e) are views showing an example where an obstacle is disposed inside a long nozzle used in the method of the present invention. FIG. 7 is a schematic view useful for explaining a single roll quenching/solidification apparatus used to cast a thin strip. FIG. 8 is an enlarged schematic view useful for explaining a casting state using a single roll quenching/solidification strip production apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing an apparatus for the production of thin strip amorphous metal used for practicing the method of the present invention. A molten alloy held inside a ladle 3 is supplied to a tundish 5 by raising a ladle stopper 1 through a long nozzle 2. Next, the molten alloy is ejected at a high speed from a nozzle 7 and impinged onto a cooling roll 8 rotating at a high speed so as to form an amorphous thin strip 7. The flow of molten alloy is controlled by an opening/closing operation of tundish stopper 4 disposed inside the tundish. The inventors of the present invention conducted intensive studies on methods of uniformly and stably supplying a molten alloy at a rate below 100 kg/min. The present inventors discovered that the feed quantity of the molten alloy depends on the length of an overlap portion between the distal end of the ladle stopper and the long nozzle. The present inventors also discovered that the feed quantity of the molten alloy depended upon the shape of the distal end of the ladle stopper and upon the area of opening defined between the ladle stopper and the long nozzle. The resistance at the time of passage of the molten alloy can be changed by using a stopper having a thin protrusion of a length of 5 mm at the distal end portion thereof as the ladle stopper. An overlap portion is provided in the horizontal direction between the distal end of the ladle stopper and the long nozzle and this overlap portion is changed. By this method, the feed quantity of the molten alloy can be controlled. If the protrusion at the distal end of the ladle stopper is elongated, the overlap portion can be set to a predetermined length even when the moving distance of the ladle stopper is large. As a consequence, even when the moving distance of the ladle stopper is increased to at least 5 mm, the feed quantity of the molten alloy can be stably reduced to a rate not greater than 100 kg/min by combining and controlling the overlap portion and the opening area (Ao) defined by this overlap portion. When the length of this overlap portion is small, however, setting of the opening area (Ao) can be controlled in the following manner. In such a case, the set position of the opening area (Ao) may be shifted below the long nozzle. It is necessary in this case, however, to change the set position of the opening area (Ao) in such a manner as to correspond to the height of the molten metal surface inside the ladle at the start of the feed of the molten alloy. The feed quantity of the molten alloy can be supplied stably and uniformly at a rate of not greater than 100 kg/min by conducting casting so that: (1) The opening area (Ao) inside the long nozzle is not greater than 1.2 cm 2 and the ratio (Ln/Lm) of the distance (Ln) from the bottom surface of the ladle to the position of the minimum sectional area inside the long nozzle to the height (Lm) of the molten metal level inside the ladle from the bottom surface of the ladle at the start of the feed of the molten alloy is at least 1.5 when the distance (y) of the overlap portion between the distal end portion of the ladle stopper and long nozzle is less than 0.1 mm. (2) The opening area (Ao) inside the long nozzle is 0.5 to 10 cm 2 when the distance (y) is from 0.1 to 200 mm. The stopper 1 used in the present invention is equipped with the protrusion 1A at the distal end thereof. This protrusion 1A has a shape corresponding to the intended production condition thin strip. The protrusion may have a small elliptic shape or a rectangular shape as shown in FIGS. 2(a) to 2(c), by way of example. When the protrusion is rectangular, the outer wall surface of this protrusion is preferably in parallel to the perpendicular direction. The example where the protrusion 1A is small and elliptic corresponds to case (1) described above. Since in this instance it is difficult to stably set the opening area (Ao) defined by the overlap portion between the distal end of the ladle stopper and the long nozzle to a predetermined value, the opening area (Ao) inside the long nozzle must be set to a value not greater than 1.2 cm 2 when the distance (y) of the overlap portion between the distal end of the ladle stopper and the long nozzle is less than 0.1 mm. The ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten metal must be set to at least 1.5. On the other hand, when the protrusion 1A has a rectangular shape and when the distance (y) of the overlap portion between the distal end portion of the ladle stopper and the long nozzle is from 0.1 to 200 mm, the opening area (Ao) inside the long nozzle must be set to 0.5 cm 2 to 10 cm 2 . The inventors of the present invention have carried out experiments and studies by using stoppers having the conventional shapes such as those shown in FIGS. 2(a) and 2(b) in order to clarify the relationship between the long nozzle opening area and the flow rate of the molten alloy in the conventional method which reduces the flow rate of the molten alloy by reducing the area of the nozzle opening portion at the distal end of this stopper. Fe--B--Si--C system amorphous alloys were primarily used for this experiment. As a result, it has been discovered that in order to set the flow rate of the molten alloy to a value not greater than 100 kg/min by the conventional method, it is necessary to set the opening area (Ao) of the long nozzle to not greater than 1.2 cm 2 , the distance (y) of the overlap portion between the distal end of the stopper and the long nozzle to less than 0.1 mm and the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy to at least 1.5, as shown in FIG. 3. It has been further discovered that once the ladle stopper 1 is elevated by a predetermined distance at the start of the feed of the molten alloy, the stopper 1 must be kept at that position until the feed of the molten alloy 6 is completed. It had been believed in the past that the molten metal generates so-called "nozzle clogging" at such a small sectional area. Therefore, the result described above is quite opposite to the common belief. Here, the term "opening area inside the long nozzle" means the minimum value of the sectional area of the long nozzle inner surface in the horizontal direction. In the case of the long nozzle which is conical and whose sectional area in the horizontal direction decreases in the flowing direction of the molten metal 6 as shown in FIG. 3, for example, the term indicates the inner area (Ao in FIG. 3) of the lowermost portion of the long nozzle 2. The terms "distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle" and "height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy" will be explained. First, the term "distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle" means the distance (Ln in FIG. 3) in the vertical direction from the bottom portion of the ladle 3 to the lowermost portion of the long nozzle 2 representing the minimum sectional area inside the long nozzle. The term "height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy" means the initial height (Lm in FIG. 3) of the molten alloy 6 held in the ladle 3. The sectional area of the long nozzle shown in FIG. 3 in the horizontal direction progressively decreases in the lower direction. Therefore, the minimum sectional area inside the long nozzle exists at the lowermost portion of the long nozzle. When the distance (y) of the overlap portion between the long nozzle and the distal end portion of the stopper is less than 0.1 mm in the long nozzle used in the present invention, the position of the opening area may be at any position inside the long nozzle if the opening area inside the long nozzle is not greater than 1.2 cm 2 . FIG. 3 shows two positions as the stop positions of the ladle stopper. That is, the position before the feed of the molten alloy 6 to the tundish is started and the position at which the molten alloy 6 is being fed. In other words, the solid line represents the former position and the dotted line, the latter position. In the present invention, the ladle stopper 1 is kept fixed at the position indicated by the dotted line while the molten alloy 6 is being fed from the ladle 3 to the tundish. The method of the present invention can keep the feed quantity of the molten alloy constant even when the ladle stopper position is fixed during the feed of the molten alloy. The reason why the feed quantity of the molten alloy can be kept constant even when the ladle stopper is fixed will be described later. Because the position of the ladle stopper can be thus fixed during the feed of the molten alloy, it is no longer necessary to measure the weight of the tundish and to control the feed quantity of the molten alloy by moving the ladle stopper position up and down as has been required in the prior art. Therefore, the molten alloy can be fed easily and economically. Incidentally, the moving distance of the ladle stopper (Ls in FIG. 3) at the start of the feed of the molten alloy is not particularly limited, but a small value is not preferred in consideration of the vibration of the apparatus. The moving distance is preferably from about 5 to about 50 mm. The inventors of the present invention have also discovered that when the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum opening area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy is set to at least 1.5, thickness fluctuations in the resulting thin strip do not occur. In other words, when the feed quantity of the molten metal changes, the height of the molten metal level of the molten alloy in the tundish changes, and this change of the molten metal level in the tundish directly results in the fluctuation of the jet pressure of the molten alloy impinged onto the cooling roll. Eventually, the fluctuations occur in the sheet thickness of the resulting thin strip. Therefore, the feed quantity of the molten alloy supplied from the ladle must be made as uniform as possible. However, when the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy is set to at least 1.5, the fluctuations of the strip thickness, which becomes a problem in the resulting thin strip, cannot be observed. This is the reason why the present invention sets the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy to at least 1.5. In other words, because the distance (Ln) from the ladle bottom surface to the minimum sectional area inside the long nozzle is set to be greater than the height (Lm) of the molten metal level inside the ladle, the influence of the height of the molten metal level inside the ladle, that affects the feed quantity of the molten alloy, becomes small. When the distance (Ln) from the ladle bottom surface to the minimum sectional area inside the long nozzle becomes at least 1.5 times the height (Lm) of the molten metal level inside the ladle, the influence of the height of the molten metal level inside the ladle that affects the feed quantity of the molten alloy presumably becomes zero. Therefore, in the present invention, no fluctuation occurs in the feed quantity of the molten alloy even when the feed quantity is not controlled by moving the ladle stopper up and down during the feeding operation of the molten alloy. In other words, the ladle stopper can be kept fixed from the start till the end of the feed of the molten alloy. The value of Ln/Lm is preferably somewhat greater that 1.5 provided that this is permitted by the installation space. If the production of the long nozzle having a minimum sectional area of not greater than 1.2 cm 2 is difficult, a long nozzle having a large sectional area is produced in advance as shown in FIGS. 6(a) to 6(e). Then an obstacle 16 having a varying shape is fitted into this long nozzle so that the resulting long nozzle has a reduced sectional area. The shape of the obstacle 16 include several different types. Examples are: at least one concentric circle obstacle, a spiral like obstacle, several protruded obstacles or porous like bricks. The sectional shape inside the long nozzle is not particularly limited in the present invention. In other words, so long as the minimum sectional area inside the long nozzle is not greater than 1.2 cm 2 , the sectional shape inside the long nozzle may be round, elliptic, polygonal or flowershaped. Further, the sectional shape inside the long nozzle may change in the flow direction of the molten alloy 6. According to the prior art, the moving distance of the stopper must be set to an extremely small value of not greater than 2 mm. The term "moving distance of the stopper" means the distance indicated by Ls in FIG. 3 and is the stroke distance (hereinafter called the "stopper stroke") at the time of opening of the stopper for feeding the molten alloy. Most setups are not free from vibration even though they may be of a precision type. In view of vibrations, it is extremely difficult to stably set the stopper stroke to not greater than 2 mm in practical operation. In view of vibrations, the stopper stroke is preferably at least about 5 mm. Therefore, the inventors of the present invention have examined feeding methods for molten alloys for setting the flow rate of the molten alloy to not greater than 100 kg/min even at a stopper stroke of at least 5 mm. The inventors found that when the long nozzle has a shape such that the inner wall surface of the opening at its upper portion is parallel to the perpendicular direction and the stopper has the protrusion at the distal end thereof whose outer wall surface is in parallel with the perpendicular direction as already described, the long nozzle opening area can be kept constant even when the stopper stroke is increased. When the y value shown in FIG. 4(a) is increased to a certain extent, the feed quantity of the molten alloy can be kept below 100 kg/min even when the long nozzle opening area exceeds 1.2 cm 2 . The stopper 1 has the protrusion 1A at the distal end thereof, according to the present invention, as shown in FIG. 2(c). The outer wall surface of this protrusion 1A is preferably parallel to the perpendicular direction. The distance (y), in FIG. 4(a), of the overlap portion between the long nozzle 2 and the stopper protrusion 1A, is set to 0.1 to 200 mm and the opening area of the long nozzle is set to 0.5 to 10 cm 2 . Moreover, the inner wall surface at the upper part of the long nozzle 2 is, or is not, brought into contact with the outer wall surface of the protrusion of the stopper so as to feed the molten alloy 6 from the ladle 3 to the tundish. Here, the term "long nozzle upper portion" means the upper end side of the long nozzle. That is, the portion near the end portion of the long nozzle connected to the ladle. More concretely, the term represents the portion within the range of about 200 mm from the uppermost end of the long nozzle towards its lower portion end. The long nozzle used for the method of the present invention is limited to those which have a shape such that the inner wall surface of this upper opening portion is parallel to the perpendicular direction. The term "inner wall surface of upper opening portion" refers to the inner wall surface of the opening indicated by reference numeral 2A in the sectional view of the long nozzle 2 in the perpendicular direction shown in FIG. 4(a). In the long nozzle 2 used for the method of the present invention the inner wall surface 2A of the upper opening portion is in parallel with the perpendicular direction means that the sectional shape of the opening portion of the long nozzle 2 in the horizontal direction has the same shape within the range of about 200 mm from the uppermost end of the long nozzle 2 towards its lower end. An important feature of the method of the present invention resides in that it uses the stopper 1 having the protrusion 1A whose outer wall surface is in parallel with the perpendicular direction. The arrangement wherein the outer wall surface of the protrusion 1A is in parallel with the perpendicular direction means that the sectional shape of the protrusion 1A in the horizontal direction has the same shape throughout the full length. FIGS. 4(a) and (b) show the best feeding method for practicing the method of the present invention. In FIG. 4(a), two positions are shown as the stop positions of the ladle stopper 1 used for the method of the present invention. That is, the position before the start of the feed of the molten alloy 6 to the tundish and the position during the feed of the molten alloy 6. In other words, the dotted line represents the former position and the solid line represents the latter position. FIG. 4(b) is an enlarged view showing the location near the fitting portion between the ladle stopper 1 and the long nozzle 2 when the ladle stopper 1 is at the position at which the molten alloy is flowing into the tundish. FIG. 5(a) is a sectional view taken along a line IV--IV in FIG. 4(b). FIG. 4(a) illustrates an example where the ladle stopper 1 has a circular cylindrical shape and the long nozzle 2 has a cylindrical shape as illustrated are in FIG. 5(a). The "distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A" and the "opening area (Ao) of the long nozzle" used in the present method will be explained with reference to FIG. 4(a). First, the term "distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A" is the distance represented by symbol y in FIG. 4(b). It is the distance of the area where the protrusion 1A of the ladle stopper 1 overlaps with the long nozzle 2 in the horizontal direction during the feed of the molten alloy. The case where this y value is from 0.1 to 200 mm will be explained in detail. The term "opening area (Ao) of the long nozzle" is the area represented by symbol Ao in FIG. 5(a) to FIG. 5(d). It is the sectional area of the space defined by the inner wall surface 2A of the opening at the upper part of the long nozzle and the outer wall surface of the protrusion 1A of the stopper 1. In the method of the present invention, the Ao value is limited to 0.5 to 10 cm 2 . In the method of the present invention, the sectional shape of the long nozzle in the horizontal direction is the same as the sectional shape of the protrusion of the stopper in the horizontal direction within the range of the distance y. Therefore, the value of the opening area Ao of the long nozzle has a constant value within the range of the distance y. The reasons why the distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A is limited to 0.1 to 200 mm and why the opening area (Ao) of the long nozzle is limited to 0.5 to 10 cm 2 in the method of the present invention will be explained. It has been discovered that even when the y and Ao values shown in FIGS. 3 and 4(a), (b) , and FIGS. 5(a) to (d) are limited to 0.1 to 200 mm and to 0.5 to 10 cm 2 , respectively, the feed quantity of the molten alloy is set to a rate not greater than 100 kg/min. This is why the distance (y) of the overlap portion between the long nozzle and the stopper protrusion is limited to 0. 1 to 200 mm and the opening area (Ao) of the long nozzle is limited to 0.5 to 10 cm 2 . Preferred combinations of the distance (y) of the overlap portion between the long nozzle and the stopper protrusion with the opening area (Ao) of the long nozzle will be illustrated concretely in the later-appearing Examples. Fundamentally, however, when the Ao value is decreased within the range described above, the y value can be decreased within the range described above. Their values may be suitably selected in accordance with a predetermined feed quantity for the molten alloy. If the Ao value is less than 0.5 cm 2 , however, clogging of the nozzle is likely to occur even though the feed is the amorphous alloy. For this reason, the method of the present invention limits the Ao value to at least 0.5 cm 2 . On the other hand, the reason why the upper limit of the Ao value is set to 10 cm 2 is to place an upper limit on the y value. The reason why the upper limit is placed on the y value is that problems would occur in fitting the stopper or during its opening and closing operations if the y value is excessively large. For these reasons, the y value is limited to not greater than 200 mm. When the y value exceeds 200 mm, centering with the long nozzle becomes difficult and fitting of the stopper also becomes difficult. If centering of the stopper with the long nozzle becomes inferior, the opening and closing operations of the stopper cannot be carried out smoothly. When the y value is set to 200 mm, the Ao value can be increased up to 10 cm 2 . This is the reason why the upper limit of Ao value is set to 10 cm 2 . The reason why the upper limit of y is 200 mm is described above. The reason why the lower limit of y is 0.1 mm is to stably set a predetermined Ao value. The stopper of the present invention is the stopper for controlling the feed quantity of the molten alloy for producing the amorphous alloy thin strip which is characterized in that the stopper has a thin protrusion, with the length of this protrusion being at least 5 mm. The outer wall surface of the protrusion is in parallel with the perpendicular direction. Here, the term "thin protrusion" means that the protrusion is so thin that it can be fitted into the opening of the long nozzle at the fitting portion with the long nozzle. The length of the protrusion of the stopper is limited to at least 5 mm. The stopper stroke must be at least 5 mm as previously discussed and the y value must be at least 0.1 mm. The discovery that "the feed quantity of the molten alloy can be set to a rate not greater than 100 kg/min even when the stopper stroke is greater than 5 mm by setting the y and Ao value to 0. 1 to 200 mm and to 0. 5 to 10 cm 2 , respectively" was made performing experiments using the Fe-B-Si-C system amorphous alloy. This phenomenon results from the fact that the viscosity of an amorphous alloy in the molten state is far smaller than that of ordinary crystalline alloys. Since this phenomenon does not only occur in the Fe-B-Si-C system amorphous alloy but is believed to occur in a broad range of alloys that can be converted to amorphous alloys, the present invention can be widely applied to a variety of amorphous alloys. According to the method of the present invention, the molten alloy can be provided supplied at a constant feed rate of not greater than 100 kg/min even when the position of the ladle stopper is fixed once the ladle stopper is moved upward at the time of the start of the feed of the molten alloy. Since the method of the present invention does not require the position of the ladle stopper to be moved up and down so as to control the flow rate of the molten alloy as has been necessary in the prior art, the operation can be carried out easily. Since the present invention does not require a complicated apparatus, it can economically supply the molten alloy. When the height of the molten metal level in the tundish fluctuates to some extent due to the effect of the decrease of the molten metal level inside the ladle in the present invention, it is advisable to eliminate the fluctuation of the molten metal level in the tundish by inserting a dummy volume, for example, into the tundish and moving up and down this dummy volume in accordance with the fluctuation of the molten metal level of the tundish. A change of the height of the molten metal level in the tundish can cause fluctuation of the jet pressure of the molten alloy impinging on the cooling roll. Eventually, this can cause a fluctuation in the sheet thickness of the resulting thin strip. Thin strips having a large thickness fluctuation generally cause problems when used as industrial materials. The method of inserting the dummy volume into the tundish and keeping constant the height of the molten metal level in the tundish is an economical method and does not significantly increase the production cost of the thin strip. The present invention does not specifically limit the stopper stroke of the ladle stopper at the start of the feed of the molten alloy. In view of the vibration of the apparatus, it is not preferred to set the stroke to an excessively small value. Preferably, therefore, the range of the stopper stroke is from about 5 to about 50 mm. FIGS. 4(a) and (b) show the case where a circular cylindrical long nozzle is used by way of example. However, the shape of the long nozzle used for the method of the present invention is not specifically limited to a circular cylindrical shape. The sectional shape of the long nozzle may be circular, elliptic, flower-like or polygonal. FIGS. 5(a) to (d) are sectional views taken along a line II--II of FIG. 4(a) and line IV--IV of FIG. 4(b). FIG. 5(b) shows the long nozzle 2 having different shapes on the outside and the inside, that is, a circular outer shape and a flower-like opening shape. Further, the shape of opening of the long nozzle can be different at its upper and lower portions. The present invention does not particularly limit the sectional shape of the protrusion on the stopper. When the shape of the opening of the long nozzle 2 is flower-shaped as shown in FIG. 5(b), for example, the shape of the overlap portion between the stopper 1 and the long nozzle 2 also may be flower-shaped. Needless to say, the sectional shape of the opening of the long nozzle 2 in the horizontal direction does not have to be similar to the sectional shape of the protrusion 1A of the stopper 1 in the horizontal direction as shown in FIGS. 5(c) and 5(d), for example. In other words, FIGS. 5(c) and (d) are sectional views taken along the line IV--IV in FIG. 4(b). As can be appreciated from FIG. 5(c), the sectional shape of the protrusion 1A may be different in the horizontal direction from the sectional shape of the opening of the long nozzle 2 such as in the combination of the stopper 1 having the protrusion 1A whose sectional shape is elliptic used with a circular cylindrical long nozzle 2. The preferred thin strip production apparatus used by the present invention is the single roll apparatus or the twin roll apparatus for jetting the molten alloy through the nozzle to the cooling substrate and quenching and solidifying the molten alloy by the thermal contact. The single roll apparatus includes a centrifugal quenching apparatus using the inner wall of a drum, an apparatus using an endless type belt, and improvement types such as those equipped with an auxiliary roll, a roll surface temperature controller, or casting in an inert gas or in vacuum at a reduced pressure. The casting conditions used for the method of the present invention and specific casting operations will be explained. The jet pressure of the molten metal is 0.01 to 3 kg/cm 2 . It is set primarily by using the height of the molten metal level inside the tundish. The rotating speed (surface speed) of the cooling roll is within the range of 5 to 60 m/sec. Optimum values are selected for these conditions in accordance with the type of the alloys used, the thickness of the intended strips and other production conditions. According to one embodiment of the method of the present invention, at least one portion of the outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle during supplying the molten alloy 6 from the ladle 3 into the tundish 5. Here, the term "outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle" represents the state shown in FIGS. 5(c). These drawing figures show embodiments where two portions of the outer wall surface of the protrusion 1A of the stopper 1 are in contact with two portions of the inner wall surface 2A of the opening at the upper portion of the long nozzle 2. The term "outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle" represents such a state. When the outer wall portion of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle, centering of the long nozzle with the stopper becomes easier. Therefore working factors during the production of the thin strip can be improved, and the supply of the molten alloy becomes easier. EXAMPLE 1 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus as shown in FIG. 1. The molten alloy was in a ladle equipped with a ladle stopper and with a long nozzle as shown in FIG. 3. The ladle stopper used was of an ordinary type having an elliptic distal end (to which a fine protrusion may be attached). The long nozzle was made of alumina graphite and its inner sectional shape was circular. It had an inner diameter of 30 mm at the uppermost portion, an inner diameter of 12 mm at the lowermost portion, and a length of 1 m. The distance (y) of the overlap portion between the distal end portion of the ladle stopper and the distal end portion of the long nozzle was adjusted to 0.08 mm. The opening area inside the nozzle was 1.13 cm 2 and the distance (Lm) from the ladle bottom surface to the minimum sectional area position inside the long nozzle was 1 m. Melting of the alloy was effected by a radio frequency induction system. The height of the molten alloy level inside the ladle before the start of feeding the molten alloy to the tundish was 250 mm. In other words, the height (Ln) of the level of the molten metal inside the ladle at the start of feeding the molten metal was 250 mm and the Ln/Lm value was 4 in this experiment. The ladle stopper used was made of alumina graphite, the same as the long nozzle, and had a cylindrical shape, a length of 800 mm and an outer diameter of 60 mm. A radius of curvature (combination of R 120 mm and R 15 mm) was applied to only the portion having a length of 35 mm at the distal end. The molten alloy was guided into the tundish by moving up the ladle stopper 20 mm. Immediately thereafter, the production of the thin strip was started by moving up the tundish stopper 20 mm. Both of the ladle stopper and the tundish stopper were kept at the 20 mm elevated positions until the production of the thin strip was completed. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm-gap; surface speed of cooling roll at casting: 20 m/sec; gap between nozzle and cooling roll: 0.3 mm. As a result, a thin strip having a width of about 120 mm and good properties could be obtained. Samples each having a length of 20 m were collected from the resulting thin strip at five positions spaced apart equidistantly in the longitudinal direction. The weight of each sample was measured. The weight was found to be about 0.95 kg for all the samples. Since each 20 m-long sample was the quantity of the thin strip produced within one second, the quantity of the molten alloy supplied to the tundish was about 57 kg/min. The thickness of the resulting thin strip was about 55 μAm. Fluctuation of the thickness in the longitudinal direction of the thin strip hardly existed. The thin strip so obtained was excellent in both magnetic and mechanical properties. It can be understood from the results described above that the feed quantity of the molten alloy by such a supplying method of the molten alloy was not greater than 100 kg/min and the molten alloy could be uniformly supplied during casting. EXAMPLE 2 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus as shown in FIG. 1. The molten alloy was in a ladle equipped with a ladle stopper and a long nozzle as shown in FIG. 4(a). The long nozzle used was made of alumina graphite and had a cylindrical shape. It had an inner diameter of 40 mm at the uppermost portion, an inner diameter of 25 mm at the lowermost portion, and a length of 1 m. The inner diameter had a constant value at the portion of a length of 200 mm from the upper-most portion to the lower portion. The lower portion had a predetermined taper. The long nozzle had an outer diameter of 60 mm for the portion having a distance of 200 mm from the uppermost portion towards the lower portion, and the outer diameter was 40 mm at the lowermost portion. The ladle stopper was made of alumina graphite, had a circular cylindrical shape having a length of 860 mm and an outer diameter of 60 mm. It had a circular cylindrical protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 4(b). Three kinds of ladle stoppers were used and the diameter of the protrusion at the distal end of each stopper was changed. Here, the protrusion at the distal end of the stopper and the long nozzle were arranged in such a fashion that they did not come into contact with each other so as to secure the opening area Ao, as shown in FIG. 5(a), (b). Melting of the alloy was effected by a radio frequency induction system. The height of the molten metal level inside the ladle before the start of feeding of the molten alloy to the tundish was 250 mm. The casting experiment was carried out with one charge for each of three kinds of ladle stoppers, that is, three charges in total. As the conditions for each casting experiment for each charge, the values of y and Ao shown in FIG. 4(a), (b) and FIG. 5(a), (b) and the value of the stopper stroke (Ls) of the ladle stopper were tabulated in Table 1. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm gap; surface speed of cooling roll at casting: 24 m/sec; gap between nozzle and cooling roll: 0.25 mm. As a result, a thin strip having a width of about 120 mm and having excellent properties was obtained. Samples, each having a length of 24 m, were collected from the resulting thin strips at five positions spaced apart equidistantly in the longitudinal direction, and the weight of each sample was measured. Since this weight represented the weight of the molten alloy supplied within one second, the feed quantity of the molten alloy at the time of casting was calculated from this data. The minimum and maximum values were tabulated in Table 1 as the results. TABLE 1______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 18 1.8 42 69-71 53-552 28 2.4 32 65-69 49-523 43 3.5 17 85-88 60-63______________________________________ As can be understood from this table, the values of the molten alloy feed quantity from the charge were substantially constant for each charge. The strip thickness of each of the 24 m-long samples collected was measured. The minimum and maximum values of the strip thickness of each sample were also tabulated in Table 1. A great fluctuation in the thickness of the thin strip could not be observed in any charge. It can be understood from this data that no fluctuation which would become a problem from the molten alloy feed quantity occurred in all the charges. The resulting thin strips were excellent in both magnetic and mechanical properties. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, substantially uniform during casting. EXAMPLE 3 Production experiments for thin strips were carried out by using the same thin strip production apparatus as in Example 2. The ladle stopper had a circular cylindrical shape having a length of 900 mm and an outer diameter of 60 mm. It had a circular cylindrical protrusion having a length of 100 mm at the distal end thereof as shown in FIG. 4(a), (b). Three kinds of ladle stoppers were used, and the diameter of the protrusion at the distal end of each ladle stopper was changed. The casting experiments were carried out by changing the values y and Ao shown in FIGS. 4(a), (b) and 5(a), (b). The values y and Ao used for the respective casting experiments were tabulated in Table 2. The surface speed of the cooling roll was set to 26 m/sec, and other casting conditions were the same as those of Example 2. As a result, thin strips having a width of about 120 mm and good properties could be obtained in all the charges. Samples each having a length of 26 m were collected from the resulting thin strips in the same way as in Example 1. The feed quantity of the molten alloy and the thickness of the thin strips were examined. Table 2 shows the results in the same way as in Table 1. From the data of the feed quantity of the molten alloy and the thickness of the thin strips tabulated in Table 2, fluctuation of the feed quantity of the molten alloy could not be observed in any charge. Fluctuations which would become the problem in the thickness of the thin strips could not be observed. TABLE 2______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 62 5.5 38 72-75 52-562 76 6.4 24 63-65 47-513 88 7.3 12 66-69 49-52______________________________________ It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, is substantially uniform during casting. EXAMPLE 4 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus shown in FIG. 1. The molten was in a ladle equipped with a ladle stopper and with a long nozzle as shown in FIG. 4(a). The long nozzle used was made of alumina graphite and had a cylindrical shape as shown in FIG. 4(a), (b). It had an inner diameter of 40 mm at the uppermost portion, an inner diameter of 25 mm at the lowermost portion and a length of 1 m. The inner diameter had a constant value at the portion of a length of 200 mm from the uppermost portion. The lower portion had a predetermined taper. The long nozzle had an outer diameter of 60 mm for the portion having a distance of 200 mm from the uppermost portion towards the lower portion, and the outer diameter was 40 mm at the lowermost portion. The ladle stopper was made of alumina graphite, had a circular cylindrical shape having a length of 900 mm, an outer diameter of 100 mm, and had an elliptic protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 5(c). The major diameter of this elliptic protrusion was 40 mm. The stopper was in slight contact with the inner wall surface of the opening at the upper portion of the long nozzle at two position at both ends of the major diameter. Three kinds of ladle stoppers were used. The minor diameter of the elliptic shape of the protrusion at the distal end of each stopper was changed. Melting of the alloy was effected by a radio frequency induction system. The height of the molten metal level inside the ladle before the start of the feeding of the molten alloy to the tundish was 250 mm. The casting experiment was carried out in one charge for each of three kinds of the ladle stoppers, i.e., three charges in total. The values of y and Ao shown in FIG. 4(a), (b) and FIG. 5(c) and the value of the stopper stroke (Ls) of the ladle stopper, as the condition of each casting experiment, are tabulated in Table 3. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm-gap surface; speed of cooling roll at casting: 24 m/sec; gap between nozzle and cooling roll: 0.25 mm. As a result, thin strips having a width of about 120 mm and good properties could be obtained in all of the charges. Samples each having a length of 24 m were collected from the resulting thin strips at five positions spaced apart equidistantly in the longitudinal direction. The weight of each sample was measured. Since this weight represented the weight of the molten alloy supplied for 1 second, the feed quantity of the molten alloy at the time of casting was calculated from this data. The minimum and maximum values of the results were tabulated in Table 3. The feed quantity of the molten metal in the charge was substantially constant for each charge as can be understood from these values. The sheet thickness was measured for each of the 24 m-long samples so collected. The minimum and maximum values of the strip thickness so obtained were also tabulated in Table 3. A great fluctuations could not be observed in the thickness of the thin strip for each charge. It could be understood from this data that no fluctuation which would become a problem resulting from the molten alloy feed quantity occurred in any of the charges. The resulting thin strips were excellent in both magnetic and mechanical properties. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, substantially uniformly during casting. TABLE 3______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 58 5.2 42 68-72 54-572 78 6.5 22 64-67 50-543 89 8.1 11 65-69 52-55______________________________________ EXAMPLE 5 Production experiments for thin strips were carried out by using the same thin strip production apparatus as in Example 4. A ladle stopper had a circular cylindrical shape, a length of 900 mm and an outer diameter of 60 mm. It had a flower-shaped protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 5(d). The y and Ao values shown in FIGS. 4(a), (b) and 5(d) were 13 mm and 1.5 cm 2 , respectively. The other casting conditions were the same as those of Example 4. As a result, thin strips having a width of about 120 mm and good properties could be obtained. Samples were collected from the resulting thin strips in the same way as in Example 1. The feed quantity of the molten alloy and the thickness of the thin strips were examined. As a result, it was found out that the feed quantity of the molten alloy was 62 to 64 kg/min and the thickness of the thin strips was 49 to 52 μm. Fluctuation of the feed quantity of the molten metal could not be observed from these data and fluctuations which would become a problem resulting from molten alloy feed quantity could not be observed. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and, furthermore, substantially uniform during casting.

A method for supplying molten metal alloy for producing thin amorphous metal wire or thin amorphous metal strip by liquid quenching and solidification on a moving cooling substrate controls the flow of molten metal from a ladle into a tundish. The ladle has a long nozzle with an interior passage for providing flow of molten metal alloy into the tundish. The ladle stopper has a distal end region received by the interior passage of the long nozzle. Control of the overlap between the distal end region of the ladle stopper received in the long nozzle during molten alloy flow and control of the sectional flow area provided in the long nozzle interior passage controls the flow quantity of molten alloy from the ladle into the tundish.

This application claims priority to provisional application Ser. No. 60/000,671 Jun. 30, 1995. FIELD OF THE INVENTION The present invention relates to a draw-down applicator for use in preparing draw-down samples, and more particularly for use in preparing draw-down samples of a coating. The present invention additionally relates to a method and kit for preparing draw-down samples. BACKGROUND OF THE INVENTION Paint customers generally select paint based upon relatively small cards having multiple colors. These cards are often referred to as "paint chips." After a paint is purchased and applied to a surface, it is sometimes found that the color of the paint does not match the color of the paint chip because of errors in formulating or mixing the paint. Improperly formulated or mixed paint is frustrating for customers, and returned paint and unsatisfied customers can be bad for a paint store's business. Accordingly, paint samples are often prepared to compare the color of recently mixed paint to the color of paint chips. Paint samples for comparing recently formulated and mixed paint to a paint chip should be sufficiently large and have a consistent film thickness so that light is properly absorbed and reflected by the sample. Accordingly, a paint brush or a roller should be used to provide a smooth surface and a sufficient thickness of paint. Using a brush or roller, however, is generally too expensive and time consuming since the brush or roller would have to be thrown out or cleaned after each use. High precision film applicators have been used in laboratories to provide coatings having precise thicknesses. For example, see BYK Gardner Catalog 90, by BYK-Gardner, Inc., Silver Spring, Md. 20910. These bars, however, are made of steel and require machining to very high tolerances, thereby increasing their expense. In addition, the film applicators are too heavy to be used conveniently, can become misaligned if dropped, and may rust or pit in water or other solvent. In order to provide a paint sample for comparison, many paint stores provide a "finger smear" of paint on a piece of scrap paper. Generally, a store clerk prepares a finger smear by dipping his finger into a can of paint and smearing the paint onto a piece of scrap paper. The clerk then either wipes off his finger or marks everything he touches with wet paint. Accordingly, a need exists for an inexpensive and convenient alternative device and method for providing samples of paint. Paint customers often desire to purchase paint which matches paint previously purchased. Many paint stores have a spectrophotometer which measures the light reflected from a sample of the paint, and an accompanying computer calculates the proper mix of pigments to provide a matching paint composition. To provide a sample for the spectrophotometer, a store clerk will prepare a paint sample on a piece of paper. Usually, the paint sample is a finger smear. Since the surface is uneven, the paint does not accurately reflect light and the correct color of the paint is often miscalculated. Since the thickness of the paint prepared by a finger smear is not uniform, thin portions can have insufficient opacity, and thereby allow the substrate color to show through. The thick portions may take some time to dry and may remain wet when handled by the customer. SUMMARY OF THE INVENTION A draw-down applicator is provided by the present invention. The draw-down applicator includes a drawing plate, a first support, and a second support. The drawing plate has a bottom drawing surface, a bottom fluid delivery surface, and first and second ends. The first support includes a bottom sliding surface and can be rigidly connected to the first end of the drawing plate. The second support has a bottom sliding surface and can be rigidly connected to the second end of the drawing bar. The bottom sliding surfaces of the first and second supports form a first plane, and the bottom drawing surface of the drawing plate forms a second plane which is parallel but not coplanar with the first plane. In a preferred embodiment of the invention, the first and second supports of the draw-down applicator each have a top sliding surface which forms a third plane; and the drawing plate has a top drawing surface which is in a fourth plane, and a top fluid delivery surface. In this embodiment, the third and fourth planes are parallel but not coplanar. The applicator is preferably made from a lightweight, non-metallic material resistant to paint solvents. The material can be anything which does not require machining, and which can be molded, preferably by injection molding. Polymeric or plastic materials are preferred. It should be appreciated that the phrase "non-metallic material" is not meant to exclude catalysts or fillers which may contain metal. Rather, it is preferred that the material is one which can be molded rather than machined into a desired shape. Exemplary polymeric materials which can be used in the invention include melt processable thermoplastic materials such as acrylonitrile butadiene-styrene resin, polystyrene, polyamide, polycarbonate, polyester, polyethylene, polypropylene, polyurethane, and mixtures thereof. In a preferred embodiment, the first plane and the second plane, and the second and third planes, respectively, are separated by a distance which is sufficient to provide a draw-down sample of a desired fluid. If the fluid has a low viscosity, the separation can be small, such as about 1 mil. If the fluid has a high viscosity or if a thick layer of the fluid is desired or if aggregate is included in the fluid, a larger distance may be desired, such as 1/8 inch. It is believed that in most applications involving latex paint as the fluid, the distance will be between about 5 mil and 10 mil. An advantage of the draw-down applicator of the invention is that it is lightweight and can be conveniently used, for example, by paint store clerks. Generally, the draw-down applicator has a weight of less than about 0.5 pound. More preferably, the weight is less than about 2 ounces, and even more preferably less than about 1 ounce. In order to provide sufficient structure, it may be difficult to provide a draw-down applicator having a weight of less than 0.1 ounce. A draw-down applicator made of acrylonitrile-butadiene-styrene resin and having drawing surfaces of about 2 inches, a drawing plate depth of about 3/16 inch and width of about 15/16 inch, and two legs having lengths of about 1.1 inch and widths of about 15/16 inch has a weight of about 0.5 ounce. A method for preparing a draw-down sample of a fluid is provided by the present invention. One step in the method includes forming a puddle of fluid on a substrate having a substantially smooth surface and wherein the substrate is separable at a predetermined location into at least two pieces. It should be appreciated that commercially available paper is generally sufficient to provide a substantially smooth surface. Although certain imperfections may be present in the substrate, a more macroscopic view should be used in determining what is "smooth." In addition, separable locations can be provided by perforations, scoring, bending and the like. Additional steps of the method include providing a draw-down applicator, and drawing the draw-down applicator over the puddle of fluid to provide a sample of the fluid having a substantially uniform thickness. It should be appreciated that a "substantially uniform thickness" describes a layer of fluid which can be provided by the draw-down applicator of the present invention. Generally, it is believed that the sample of fluid having a substantially uniform thickness will be provided on commercially available paper and may have imperfections caused by the texture of the paper. The method can additionally include a step of removing a dipper from the substrate and using the dipper to scoop the fluid and apply it to the substantially smooth surface. Furthermore, the method can include allowing the drawn fluid to dry, and separating the substrate along a predetermined separable location to provide at least two separated substrates having drawn fluid thereon. It is particularly preferred that the fluid is paint. Alternative fluids, such as, ink, stain, protective finish, and the like, can be used in by the present invention. A kit for preparing draw-down samples is provided by the present invention. The kit includes a draw-down applicator and a substrate separable at a predetermined location. The substrate is preferably paper which is separable to provide a dipper section and a fluid coatable section. The kit can additionally include a portable smooth and rigid platform which can be used to provide a smooth surface against which the substrate is placed and the draw-down applicator is drawn. Preferably, the kit includes a wash basin for washing the applicator. The wash basin can be a bucket or bowl having sufficient dimensions to hold enough water or other solvent to satisfactorily clean the draw-down applicator after it has been used. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a draw-down applicator according to the principles of the present invention; FIG. 2 is a front view of the draw-down applicator of FIG. 1; FIG. 3 is cross sectional view taken along line 3--3 of the draw-down applicator of FIG. 1; FIG. 4 is a top view of a draw-down card according to the principles of the present invention; FIG. 5 is a bottom view of the draw-down card shown in FIG. 4; and FIG. 6 is a perspective view, in operation, of a kit for preparing a draw-down sample. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiment of the invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to the preferred embodiment does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Referring to FIGS. 1-3, an embodiment of a draw-down applicator of the present invention is provided at 10, and may be referred to as the applicator. The draw-down applicator 10 includes drawing region 12, first guiding region 14, and second guiding region 16. Preferably, the applicator 10 is an integral piece. It is to be understood that the word "integral" refers to the draw-down applicator 10 being a continuous material which does not separate into subparts except by fracturing. Alternatively, the applicator can be made of parts which snap together to provide an assembled applicator. The drawing region 12 includes a drawing plate 18 having a bottom drawing surface 20 and a bottom fluid delivery surface 22, and a top drawing surface 24 and a top fluid delivery surface 26. As a matter of convenience, one side of the applicator 10 can be referred to as the top side 15 and the opposed side can be referred to as the bottom side 17. It should be appreciated that the designation of "top" and "bottom" reflects opposed surfaces or sides of the applicator 10. Since the applicator 10 is so small and lightweight, it can easily be turned over so that the bottom side 17 is above or "on top of" the top side 15. As will be described in more detail, the fluid delivery surfaces 22, 26 are provided to meter or control the flow of fluid to the drawing surfaces 20, 24 to form a thin film of fluid on a substrate when the applicator 10 is drawn over a puddle of fluid. Accordingly, the angle of the fluid delivery surfaces 22, 26 to the drawing surfaces 20, 24 is provided based upon intended flow properties. One having skill in the art would readily appreciate how fluid rheology effects these angles. For many latex paints, it is acceptable to provide a 45 degree angle as shown. The first guiding region 14 includes a first leg 19 having a bottom sliding surface 28 and a top sliding surface 30. Similarly, the second guiding region 16 includes a second leg 23 having a bottom sliding surface 32 and a top sliding surface 34. The bottom drawing surface 20 lies in a bottom drawing plane which is parallel to the bottom sliding plane formed by the bottom sliding surfaces 28, 32. Similarly, the top drawing surface 24 lies in a top drawing plane which is parallel to the top sliding plane formed by the top sliding surfaces 30, 34. It should be understood that the bottom drawing surface need not entirely be within the bottom drawing plane, and that the top drawing surface need not entirely be within the top drawing plane. In other words, the drawing surfaces can be provided at any desired angle to the sliding surfaces. However, the bottom drawing plane is not coplanar with the bottom sliding plane, and the top drawing plane is not coplanar with the top sliding plane. It is the discontinuity between these plane, or expressed differently, it is the discontinuity along the surfaces 28, 20, 32 and along the surfaces 30, 24, 34 which is important for providing slots 21, 25, respectively, which allow the draw-down applicator 10 to provide draw-down samples as will be described in more detail. The slots 21, 25 are provided with sufficient depth to provide a desired thickness of fluid to flow therethrough. Preferably, the coating provided by the applicator has a substantially uniform thickness on a substrate. It is to be understood that a "substantially uniform thickness" is meant to include a coating on paper where the coating can have irregularities due to pores or fibers therein. For applicator 10, as an example, the distance between the bottom drawing plane and the bottom sliding plane is 8/1000 inch (8 mils) and is indicated by the raised markings 40 on the front of the drawing plate 18. The distance between the top drawing plane and the top sliding plane is 6/1000 inch (6 mils) and is indicated by the raised markings 42. It has been found that for most commercially available paints, these slot sizes are sufficient for providing adequate draw-down samples. For most applications, the slot depth should be above about 1 mil and less than about 10 mil. However, alternative slot sizes can be provided depending, for example, on the viscosity of the fluid and the desired thickness of the coating. The beveled surfaces 46, 48, 51, 53, 55, 56 are provided to reduce the angle of the edges and to reduce the amount of material used to prepare the applicator 10. This additionally keeps the applicator lighter in weight. In addition, the beveled surfaces 51, 53, 55, 56 help reduce the surface area of the sliding surfaces 28, 30, 32, 34 which helps reduce friction and allows the applicator 10 to slide or glide more easily over the surface of a substrate. When the applicator 10 is used to provide a draw-down sample, either the top side 15 or the bottom side 17 is slid across the surface of a substrate. Preferably, the surface of the substrate is a substantially smooth surface. As used herein, a "substantially smooth surface" is a surface which is sufficiently even and uniform to provide a draw-down sample having a relatively consistent coating or film thickness using the draw-down applicator of the present invention. Generally, commercially available paper would be capable of providing a substantially smooth surface. To help provide a substantially smooth surface, a smooth and rigid platform can be placed under the substrate. Exemplary platforms include fixed or relatively immovable objects such as tables, counters, desks, and the like, or portable objects such as glass or metal plates, plexiglass, fiberglass, or other plastic sheet, and the like. A substrate which can be used to provide a draw-down sample according to the present invention is provided in FIGS. 4 and 5, and is referred to as draw-down card 50. The draw-down card 50 has a first side 52 and a second side 54. The draw-down card 50 includes perforations 56, 58, 60 which allow for separation of portions of the card into take home section 62, retention section 64, excess paint section 66, and a dipper section 68. It is preferred to provide a draw-down sample across the first side of the take home section 62 and the retention section 64. It is noted that in place of the perforations, the card can have slits, scoring, indentations, markings, and the like which identify a suitable area for separation by, for example, tearing, cutting, etc. In a preferred embodiment for providing a draw-down sample of latex paint, the dipper section 68 is removed and folded along score line 69 to provide a V-shaped dipper. The remaining part of the card 50 can be placed on a flat and level surface with the first side up. The dipper can be dipped into the paint, and the paint in the dipper can be applied over the paint application line 70 to substantially cover the line and form a puddle of paint. It should be appreciated that the size of the line 70 can be used to indicate a predetermined sufficient amount of paint needed to provide an acceptable draw-down sample. Once the paint has been applied, the dipper can be thrown away. The draw-down applicator 10 can be placed around the puddle of paint so that either the bottom sliding surfaces 28, 32 or the top sliding surfaces 30, 34 are resting on the first surface of the draw-down card 50. Thus, the legs 19, 23 are positioned around the puddle so that the drawing plate 18 is ready to engage the puddle once the applicator 10 is drawn thereover. If the bottom side of the applicator 10 is placed on the card 50, once the card is drawn, the fluid flows over the bottom fluid delivery surface 22 so that the bottom drawing surface 20 provides a coating having a consistent thickness on the card. Once the drawing plate 18 engages the puddle of fluid, the tendency of the fluid would be to spread out. The legs 19, 23, however, typically contain the fluid within the applicator 10 so that a draw-down sample having a width which is equal to the distance between the legs 19, 23 is provided. In a substantially continuous motion, the applicator 10 draws the puddle of paint over the sections 62, 64, 66. An embodiment showing the end of this drawing stage is provided in FIG. 6 showing plexiglass platform 71, draw-down sample 75, and puddle of excess paint 77. Once the draw-down sample 75 is completed, the draw-down applicator 10 can be placed in a wash-up bin or bucket filled with cleaning solution such as water or turpentine, and the excess paint section 66 can be removed along perforation 58 from the card 50 and discarded. The remaining sections 62, 64 can be hung on a hook via hole 72 until the paint dries. It is an advantage of the present invention that the applicator 10 can be easily cleaned since the surfaces are relatively smooth. Alternatively, the applicator 10 is sufficiently inexpensive that it can be disposed or recycled. Furthermore, it is an advantage that draw-down samples can be prepared without creating a mess and without requiring hand cleaning afterwards. The dipper 68 and the excess paint section 66 containing the puddle of excess paint 77 are discarded. It is another advantage that the draw-down card 50 containing a wet draw-down sample 75 can be hung in an out of the way place until the sample dries. Accordingly, the present invention provides for increased organization in preparing draw-down samples. The card 50 can include additional information. For example, the first side of the take home section 62 includes an area for identifying the paint 73, and the second side of the take home section 62 includes an area for identifying the application of the paint 74 and an area for identifying the paint store 76. The second side of the retention section 64 includes an area for identifying the customer and the paint. The take home section 62 can be kept by the customer and the retention section 64 can be kept by the paint store for its records. It should be appreciated that the draw-down card can be modified to provide any information desired. In addition, multiple draw-down cards can be prepared. For example, it may be desirable for architects or contractors to provide draw-down samples to clients along with plans. In such cases, it may be helpful to prepared additional draw-down samples for the store's records, for the architect's records, and for the client's records. Alternatively, the card can be modified to be used in other applications, such as in a laboratory. In such an application, for example, it may be desired to provide only two perforated line, one for separation of the dipper and one for separation of the excess paint section. It is an advantage of the present invention that relatively large samples of paint, or large paint chips, can be inexpensively and conveniently prepared and taken home by paint customers for evaluation. It is understood that paint often looks different in various lighting conditions, and/or when applied to a large surface. It is believed that by providing large samples of paint for customers to evaluate, customer satisfaction with selected paints will increase. Accordingly, the size of the applicator can be modified to provide a desired size draw-down sample. It is preferred that the width of the substrate on which the draw-down sample is prepared is larger than the overall width of the draw-down applicator. This helps provide a substantially consistent film thickness. It is an additional advantage of the present invention that the draw-down applicator can be easily and inexpensively prepared, and can provide desired accuracy in preparing a draw-down sample. As discussed above, high precision film applicators have been used in laboratories to provide coatings having precise thicknesses. These bars, however, are heavy and expensive. The applicator of the invention provides significantly low distribution costs due to its light weight. In addition, it is an advantage of the present invention that the draw-down applicator is light and easy to use, inexpensive to manufacture, and resists corrosion and pitting in water and many solvents commonly used in coating compositions. In addition, the draw-down applicator is sufficiently rigid to resist bending out of shape if dropped. It should be appreciated that many types of fluid can be used with the draw-down applicator and/or the draw-down card of the present invention. Preferably, the fluid is a type which provides a coating on a substrate. Exemplary fluids include paints such as latex and oil based paints, and consumer and industrial paints, finishes such as polyurethane and polyacrylic finishes, stains, and the like. A preferred fluid which can be used to provide a draw-down sample is latex paint since the draw-down applicator can be easily cleaned in water afterwards. The applicator 10 can generally be used on a level or tilted surface. It is desirable, however, that the surface is sufficiently level so as to resist the flow of fluid in any one direction caused by the force of gravity. It is understood that when a fluid is applied to a perfectly level surface, it theoretically will flow in all directions equally. It is desirable, however, that the draw-down applicator provides the force which displaces the fluid to provide the draw-down sample. It should be appreciated that the ability of a fluid to flow is a function of viscosity, and that certain paint compositions are intended to be applied to vertical walls. Thus, the degree of tilt or slant of the substrate is a function of the rheology of the paint composition. For example, if a paint if very viscous, it will resist flow caused by gravity. In contrast, a very low viscosity fluid may exhibit runny characteristics. It is generally desirable that when a paint composition is applied to the substrate, it remains in a puddle and does not flow until drawn by the applicator 10. The draw-down applicator of the present invention can be manufactured without machining. Preferably, the draw-down applicator is prepared, for example, by injection molding or compression molding. Materials which can be used to prepare the draw-down applicator are preferably polymeric materials resistant to solvents normally found in paint composition, and which are melt processable thermoplastics. Exemplary polymeric materials include acrylonitrile-butadiene-styrene (ABS) resin, polystyrene, polyamide, polycarbonate, polyester, polyethylene, polypropylene, polyurethane, mixtures thereof and the like. When preparing the draw-down applicator by injection molding, it is desirable for the walls to be as thin as possible to decrease manufacturing time, yet sufficiently thick to provide desired stability. Thicker walls generally take longer to cool before they can be removed from a mold. Preferably, the wall thickness should be in the range of about 1/4 to 1/16 inch. In order to decrease the wall thickness and provide a sufficiently high manufacturing rate, the first and second legs 19, 23 of the applicator 10 are provided with stabilizers 45 which allow the applicator 10 to be more quickly removed from an injection mold. The stabilizers 45 have a sufficient diameter which allow injector pins to push against the ends thereof to push the applicator out of the mold. Thus, as the diameter of the stabilizers 45 decreases, the time need to cure or solidify before removal from the mold increases. Generally, a diameter in the range of about 1/4 to 1/8 inch is sufficient to provide a desired manufacturing rate. The stabilizers 45 may additionally help reduce warping or bending of the legs. Unless the sliding surfaces are in one plane, the thickness of a film prepared by the applicator may not be sufficiently even. It is believed that warping may increase over time without the stabilizers. In addition, it is believed that the stabilizers may help increase heat transfer thereby decreasing the time to make the applicator. Advantageously, the stabilizers help provide a gripping surface on the sides of the legs when pulling the applicator across a substrate. It should be appreciated that the draw-down applicator and the draw-down card of the present invention can be useful for applications outside of a paint store environment. For example, they can be useful in laboratories, graphic arts applications, and the like. A preferred material for use as the substrate includes 10 point paper coated one side cast coat paper. One commercially available paper stock is CROMECOTE 2000 sold by Champion Paper. It is preferable to provide the draw-down sample on the side of the paper coated with a high gloss coating and provide written information on the uncoated side. It should be kept in mind, however, that uncoated paper can also be used, including any other substrate which is capable of receiving a coating by the draw-down applicator of the present invention. While the invention has been described in conjunction with specific embodiments thereof, it is evident that different alternatives, modifications, variations, and uses will be apparent to those skilled in the art in view of the foregoing description. Accordingly, the invention is not limited to these embodiments or the use of elements having specific configurations and shapes as presented herein.

A method for preparing draw-down samples of paint using a draw-down applicator is provided. The draw-down applicator comprises a drawing plate having a bottom drawing surface and a bottom fluid delivery surface; a first support or arm having a bottom sliding surface and being rigidly connected to the first drawing plate; and a second support having a bottom sliding surface and being rigidly connected to the drawing plate. The bottom sliding surfaces of said first and second supports form a first plane, and the bottom drawing surface of said drawing plate is in a second plane. The two planes are parallel but not coplanar. Furthermore, the applicator is a non-metallic material. The method includes forming a puddle of paint on a substrate having a substantially smooth surface and drawing the draw-down applicator over the puddle of paint so that the applicator delivers a substantially uniform thickness of the paint over the substrate.

[0001] This application is a continuation of co-pending U.S. patent application Ser. No. 09/229,287 filed Jan. 13, 1999 which is a continuation in part of co-pending provisional application serial No. 60/071,310, filed Jan. 13, 1998. FIELD OF THE INVENTION [0002] The present invention is directed to methods, compositions, kits and apparatus to identify and detect the presence or absence of target analytes. The embodiments of the present invention have utility in medical diagnosis and analysis of various chemical compounds in specimens and samples, as well as the design of test kits and apparatus for implementing such methods. BACKGROUND OF THE INVENTION [0003] Molecular biology advances in the last decade gave great promise for the introduction of new, sensitive technologies to identify various analytes in test specimens, including the ability to diagnose cancer, infectious agents and inherited diseases. Clinical molecular diagnostics depend almost exclusively on restriction enzyme analyses and nucleic acid hybridization (Southern and Northern blots) (Meselson and Yuan, 1968, Southern, 1975). Clinical tests based on molecular biology technology are more specific than conventional immunoassay procedures and can discriminate between genetic determinants of two closely related organisms. With their high specificity, nucleic acid procedures are very important tools of molecular pathology. However, nucleic acid procedures have limitations, the most important of which are the procedures consume time, are labor intensive and have low sensitivity (Nakamura 1993). [0004] There exists a need to perform analytical and diagnostic assays of high sensitivity and high specificity. There exists a need for analytical methods, compositions and devices which facilitate the performance of a analytical or diagnostic procedure in less than one hour. There exists a need for analytical methods, compositions and devices which are directed to targets which are present in cells in quantities less than one to one thousand copies. There exists a need for analytical and diagnostic procedures which identify small or large organic molecules, peptides or proteins, the tertiary structure of nucleic acids or complex or simple carbohydrates. SUMMARY OF THE INVENTION [0005] The present invention features methods, compositions, kits, and apparatus for determining the presence or absence of a target molecule. One embodiment of the present invention is a composition. The composition comprises a first ribonucleic acid (RNA) molecule. The first RNA molecule binds a target molecule and has the following formula: 5′-A-B-C-D-E-3′. [0006] As used above, A is a section of the RNA molecule having 10-100,000 nucleotides which section is, with another RNA sequence, E, replicated by an RNA replicase. The letter “B” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence D, binds the target molecule under binding conditions. The letter “C” denotes a section of the RNA molecule having approximately 1 to 10000 nucleotides which section is capable preventing the replication of the first molecule by the RNA replicase. The letter “D” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence B, binds the target molecule under binding conditions. The sections B and D, in combination, comprise in total at least 10 nucleotides. The first RNA molecule, with sections B and D bound to target, is acted upon by the RNA replicase to form a second RNA molecule. The second RNA molecule has the following formula: 5′-E′-X-A′-3′. [0007] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. The second RNA molecule is replicated by the RNA replicase under replicating conditions. [0008] Preferably, the sequences represented by the letters “A” and “E” are selected from the group of sequences consisting of MDV-I RNA, Q-beta RNA microvariant RNA, nanovariant RNA, midivariant RNA, RQ-135 and modifications of such sequences which maintain the ability of the sequences to be replicated by Q-beta replicase. Preferably, the replicase is Q-beta replicase. [0009] Preferably, the sections B and D have a combined total of 20-5,000 nucleotides and, even more preferred, 20-50 nucleotides. Preferably, the sections B and D bind to target through non-nucleic acid base pairing interactions. Sections B and D bind to the target in the manner of naturally occurring nucleic acid which form RNA-protein complexes. Or, the B and D sections are non-naturally occurring sequences which are selected to bind the target. These non-naturally occurring sequences are selected by computer modeling, or aptamers or partial aptamers, and other nucleic acids exhibiting affinity to the target. The term “aptomer” is used in the manner of Klug, S. J. and Famulok, M. “All you wanted to know about SELEX”, Molecular Biology Reports, 20:97-107 (1994) and other nucleic acids which are selected for affinity to a selected target. Aptamers are selected for a particular functionality, such as binding to small or large organic molecules, peptides or proteins, the tertiary structure of nucleic acids or complex or simple carbohydrates. [0010] Preferably, the section B has a hybridization sequence of 1-100, and more preferred, 1-50, and most preferred, 1-5 nucleotides adjacent to the section A which form a hybridization product with a complementary hybridization sequence of section D. The nucleotides of the hybridization sequence of section D are adjacent section E. The hybridization sequences of sections B and D preferably define a loop, bulge or other single stranded structure at such times that section B and D are bound to target. In the absence of target, the hybridization sequences do not form a stable hybridization product. In the presence of the target, and the formation of a complex between sections B and D with the target, a hybridization product is formed that allows the RNA replicase to skip sections B, C and D and replicate sections A and E. [0011] Preferably, X comprises less than five nucleotides of sections B and D, and the second molecule resembles a wild-type template. [0012] Preferably, the section C has 1-10,000 nucleotides, and more preferred, 1-1000 nucleotides, and most preferred, 1-100 nucleotides which sequences define a stop sequence for the RNA replicase. Stop sequences comprise one or more sequences which the RNA replicase can not read through to effect replication of the sequence. These sequences include, by way of example, without limitation, a sequence of poly A, poly C, poly G, multiple initiation sites, modified nucleotides which do not allow the RNA replicase to act on the sequence, sugar linkages without nucleotides and altered phosphate or sugar linkages. [0013] Preferably, the sections A and E comprise at least one sequence that hybridizes to a third nucleic acid. Such third nucleic acid forms a hybridization product which hybridization product can be detected by known means. [0014] A second embodiment of the present invention features paired RNA molecules comprising a first RNA molecule. The first RNA molecule binds a target molecule and has the following formula: 5′-A-F-B-3′. [0015] And, the second RNA binds the target and has the following formula: 5′-D-H-E-3′ [0016] As used above, A is a section of the RNA molecule having 10-100,000 nucleotides which section is, with another RNA sequence, E, replicated by an RNA replicase. The letter “B” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence D, binds the target molecule under binding conditions. The letter “D” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence B, binds the target molecule under binding conditions. The sections B and D, in combination, comprise in total at least 10 nucleotides. The letter “F” denotes a section of the RNA molecule having has a hybridization sequence of 1-10,000, and more preferred, 1-50, and most preferred, 1-5 nucleotides which form a hybridization product with a complementary hybridization sequence of section H. The letter “H” denotes a section of the RNA molecule having has a hybridization sequence of 1-10,000, and more preferred, 1-50, and most preferred, 1-5 nucleotides which form a hybridization product with a complementary hybridization sequence of section F. The hybridization sequences of sections F and H preferably define a hairpin or double stranded structure at such times that section B and D are bound to target. In the absence of target, the hybridization sequences do not form a stable hybridization product. In the presence of the target, and the formation of a complex between sections B and D with the target, a hybridization product is formed that allows the RNA replicase to skip sections B and D and replicate sections A and E to form a third RNA molecule. The third RNA molecule has the following formula: 5′-E′-X-A′-3′. [0017] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, F, H and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. The third RNA molecule is replicated by the RNA replicase under replicating conditions. Preferably, X comprises less than five nucleotides of the complement of sections B and D, and the third molecule resembles a wild-type template. [0018] Preferably, the sections F and H may comprise sequences which are associated with RNA replicase templates. [0019] A further embodiment of the present invention features a method of determining the presence or absence of a target molecule. One method comprises the steps of providing a first RNA molecule. The first RNA molecule is capable of binding to a target molecule and has the formula: 5′-A-B-C-D-E-3′. [0020] The sections A, B, C, D and E are as previously described. The method further comprises the step of imposing binding conditions on a sample potentially containing target molecules in the presence of the first RNA molecule. In the presence of the target molecule, the first RNA molecule forms a target-first RNA molecule complex. The method further comprises the step of imposing RNA replicase reaction conditions on the sample, in the presence of an RNA replicase, to form a second RNA molecule in the presence of target. The second RNA molecule has the formula: 5′-A′-X-E′-3′. [0021] The sections A′, X and E′ are as previously defined. The sample is monitored for the presence of the second RNA molecule or its complement, which presence or absence is indicative of the presence or absence of the target molecule. [0022] A second method comprises the steps of providing paired RNA molecules comprising a first RNA molecule and a second RNA molecule. The first RNA molecule is capable of binding to a target molecule and has the formula: 5′-A-F-B-3′. [0023] The second RNA molecule has the formula: 5′-D-H-E-3′ [0024] The sections A, B, D, E, F and H are as previously described. The method further comprises the step of imposing binding conditions on a sample potentially containing target molecules in the presence of the first RNA molecule and second RNA molecule. In the presence of the target molecule, the first RNA molecule and the second RNA molecule forms a target-first second RNA molecule complex. The method further comprises the step of imposing RNA replicase reaction conditions on the sample, in the presence of an RNA replicase, to form a third RNA molecule in the presence of target. The third RNA molecule has the formula: 5′-E′-X-A′-3′. [0025] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, F, H and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. [0026] A further embodiment of the present invention comprises a kit for determining the presence or absence of a target molecule. The kit comprises a one or more reagents comprising a first RNA molecule for use with an RNA replicase. The first RNA molecule has the formula: 5′-A-B-C-D-E-3′. [0027] In the presence of target, the first RNA molecules is capable of forming a target-first-RNA complex and in the presence of an RNA replicase, forming a second RNA molecule having the formula: 5′-A′-X-E′-3′. [0028] The letters A, B, C. D, E, A′ E′ and X are as previously described. The second RNA molecule is preferably capable of being replicated by Q-beta replicase. [0029] A second embodiment of the kit for determining the presence or absence of a target molecule features paired RNA molecules. The kit comprises a one or more reagents comprising a first RNA molecule and a second RNA molecule. The first RNA molecule has the formula: 5′-A-F-B-3′. [0030] The second RNA molecule has the formula: 5′-D-H-E-3′ [0031] In the presence of target, the first RNA molecule and the second RNA molecule are form a target-first-second RNA complex and in the presence of an RNA replicase, forming a third RNA molecule having the formula: 5′-A′-X-E′-3′. [0032] The letters A, B, C. D, E, ,F, H, A′ E′ and X are as previously described. The third RNA molecule is preferably capable of being replicated by Q-beta replicase. [0033] An embodiment of the present invention further comprises a method of making a first RNA molecule, wherein the first RNA molecule has the formula: 5′-A-B-C-D-E-3′. [0034] As used above, the letters A, B, C, D, and E are as previously described. The method comprises the step of combining a sample containing the target molecule with a library of RNA molecules having the formula: 5′-A-B′-C-D′-E-3′. [0035] to form a mixture of one or more target bound RNA molecules and one or more unbound RNA molecules. The letters B′ and D′ represent potential sections B and D. Next, primer nucleic acid corresponding to at least one section is added to the mixture with an enzyme capable of degrading the unbound RNA molecules. Next, bound RNA molecules are released from target and amplified to form an amplification product. Next, the RNA molecules comprising the amplification product having the formula: 5′-A-B′-C-D′-E--3′ [0036] are sequenced. Or, a cDNA formed and such cDNA cloned into suitable vectors. [0037] Preferably, the steps of forming a mixture, degrading unbound RNA molecules and amplifying the bound RNA molecules are repeated. [0038] Preferably, the sections B′ and D′ are randomized nucleotides. Or, in the alternative, are generated through in vitro selection. [0039] Preferably the step of degrading the unbound RNA molecules is performed in the presence of the enzyme reverse transcriptase. Sections B and D identified in the method above can be used to make paired RNA molecule of the formula: 5′-A-F-B-3′; and, 5′-D-H-E-3′. [0040] An embodiment of the present invention further comprises a kit for performing the above method of identifying first and second RNA molecules. The kit comprises one or more nucleic acid molecules having sections corresponding to the sections A, B′, C, D′, and E. Preferably, the kit comprises sections B′ and E′ as randomized nucleotide sequences. [0041] As used herein the term “kit” refers to an assembly of parts, compositions and reagents with suitable packaging materials and instructions. [0042] The present invention is further described in the following figure and examples, which illustrate features and highlight preferred embodiments and the best mode to make and use the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0043] [0043]FIG. 1 depicts a kit having features of the present invention; [0044] [0044]FIG. 2 depicts plasmid pT7 MDV-XhoI; [0045] [0045]FIG. 3 depicts the binding element of an aptamer for ATP; [0046] [0046]FIG. 4 depicts a modified MDV-1 template; and [0047] [0047]FIGS. 5 a, 5 b, and 5 c depict plasmid construction. DETAILED DESCRIPTION [0048] The present invention features methods, compositions, kits, and apparatus for determining the presence or absence of a target molecule. The target molecule may comprise any small or large organic molecules, peptides or proteins, the tertiary structure of nucleic acids or complex or simple carbohydrates the detection of which is desired. [0049] This detailed description will begin with a close examination of one embodiment of the present invention. The composition comprises a first RNA molecule. The first RNA molecule binds a target molecule and has the following formula: 5′-A-B-C-D-E-3′. [0050] As used above, A is a section of the RNA molecule having 10-100,000 nucleotides which section is, with another RNA sequence, E, replicated by an RNA replicase. [0051] Preferably, the sequences represented by the letters “A” and “E” are selected from the group of sequences consisting of MDV-I RNA, Q-beta RNA microvariant RNA, nanovariant RNA, midivariant RNA, RQ-135 and modifications of such sequences which maintain the ability of the sequences to be replicated by Q-beta replicase. Preferably, the replicase is Q-beta replicase. [0052] The sequence of MDV-I RNA has been widely reported. For convenience, it is presented below as Seq. ID No. 1. Seq. ID No. 1 5′ G GGGACCC CC CCGGAAGGGG GGGACGAGGU GCGGGCACCU UGUACGGGAG UUCGACCGUG ACGCAUAGC A GGCCUCGAGA UCUAGA GCAC GGGCUAGCGC UUUCGCGCUC UCCCAGGUGA CGCCUCGUGA AGAGGCGCGA CCUCGUGCGU UUCGGCAACG CACGAGAACC GCCACGCUGC UUCGCAGCGU GGCUCCUUCG CGCAGCCCGC UGCGCGAGGU GACCCCCCGA AGGGGGGUU C CCGGGAAUUC 3′. [0053] A preferred sequence derived from MDV-I RNA for sequences represented by the letter A, is set forth below as Seq ID No. 2: Seq. ID No. 2 5′ GGGGACCCCC CCGGAAGGGG GGGACGAGGU GCGGGCACCU UGUACGGGAG UUCGACCGUG ACGCAUAGCA GGAA UU 3′ [0054] A preferred sequence derived from MDV-I RNA for sequences represented by the letter E, is set forth below as Seq ID No. 3: Seq. ID No. 3 5′-GGGGACCCCC CGGGCCUCGA GAUCUAGAGC ACGGGCUAGC GCUUUCGCGC UCUCCCAGUG ACGCCUCGUG AAGAGGCGCG ACCUUCGUGC GUUUCGGCAA CGCACGAGAA CCGCCACGCU GCUUCGCAGC GUGGCUCCUU CGCGCAGCCC GCUGCGCGAG GUGACCCCCC GAAGGGGGGU UCCC-3′ [0055] A preferred sequence derived from RQ-135 for sequences represented by the letter A, is set forth below as Seq ID No. 4: Seq. ID No. 4 5′-GGGGUUUCCA ACCGGAAUUU GAGGGAUGCC UAGGCAUCCC CCGUGCGUCC CUUUACGAGG GAUUGUCGAC UCUAGUCGAC -3′ [0056] A preferred sequence derived from RQ-135 for sequences represented by the letter E, is set forth below as Seq ID No. 5: Seq. ID No. 5 5′-GGUACCUGAG GGAUGCCUAG GCAUCCCCGC GCGCCGGUUU CGGACCUCCA GUGCGUGUUA CCGCACUGUC GACCC-3′ [0057] The letter “B” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence D, binds the target molecule under binding conditions. The letter “D” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence B, binds the target molecule under binding conditions. The sections B and D, in combination, comprise in total at least 10 nucleotides. [0058] Preferably, the sections B and D have a combined total of 20-5,000 nucleotides and, even more preferred, 20-50 nucleotides. Preferably, the sections B and D bind to target through non-nucleic acid base pairing interactions. Sections B and D bind to the target in the manner of naturally occurring nucleic acid which form RNA-protein complexes. Or, the B and D sections are non-naturally occurring sequences which are selected to bind the target. These non-naturally occurring sequences are selected by computer modeling, or aptamers or partial aptamers, and other nucleic acids exhibiting affinity to the target. [0059] The term “aptamer” is used in the manner of Klug, S. J. and Famulok, M. “All you wanted to know about SELEX”, Molecular Biology Reports, 20:97-107 (1994) and other nucleic acids which are selected for affinity to a selected target. Aptamers are selected for a particular functionality, such as binding to small or large organic molecules, peptides or proteins, the tertiary structure of nucleic acids or complex or simple carbohydrates. The sequences for nucleic acids that bind to a polymerase, bacteriophage coat protein, serine protease, mammalian receptor, mammalian hormone, mammalian growth factor, ribosomal protein, and viral rev protein are disclosed in U.S. Pat. No. 5,475,096. The method presented in such patent may also be used to identify other aptamer sequences. [0060] In addition, nucleic acids which bind to a target may also be identified by in vitro selection. After such nucleic acid has been selected and identified, such nucleic acid is sequence in a manner known in the art. [0061] Preferably, the section B has a hybridization sequence of 1-100, and more preferred, 1-50, and most preferred, 1-5 nucleotides adjacent to the section A which form a hybridization product with a complementary hybridization sequence of section D. The nucleotides of the hybridization sequence of section D are adjacent section E. The hybridization sequences of sections B and D preferably define a loop or hairpin at such times that section B and D are bound to target. In the absence of target, the hybridization sequences do not form a stable hybridization product. In the presence of the target, and the formation of a complex between sections B and D with the target, a hybridization product is formed that allows the RNA replicase to skip sections B, C and D and replicate sections A and E. [0062] The Example of this application uses nucleic acid which binds adenosine triphosphate (ATP). A preferred sequence for section B is set forth below as Seq. ID No. 6: [0063] Seq ID No. 6 [0064] 5′-AGUUGGGA AGAAACUGUG GGACUUCG-3′ [0065] A preferred sequence for section D is set forth below as Seq. ID No. 7: [0066] Seq ID No. 7 [0067] 5′-GUCCCA GCAACU-3′ [0068] The letter “C” denotes a section of the RNA molecule having approximately 1 to 10000 nucleotides which section is capable preventing the replication of the first molecule by the RNA replicase. Preferably, the section C has 1-10,000 nucleotides, and more preferred, 1-1000 nucleotides, and most preferred, 1-100 nucleotides which sequences define a stop sequence for the RNA replicase. Stop sequences or signals comprise one or more sequences which the RNA replicase can not read through to effect replication of the sequence. These sequences include, by way of example, without limitation, a sequence of poly A, poly C, poly G, multiple initiation sites, modified nucleotides which do not allow the RNA replicase to act on the sequence, sugar linkages without nucleotides and altered phosphate or sugar linkages. [0069] A preferred stop sequence is such sequence recognized by the enzyme ricin and or sarcin. Ricin acts on such sequence to effect a modification of the nucleic acid, the removal of the base. Such a preferred sequence for the section C is set forth below as Seq ID No 8: [0070] Seq ID No. 8 [0071] 5′-AUGUACG AGAGGACC-3′ [0072] The first RNA molecule, with sections B and D bound to target, is acted upon by the RNA replicase to form a second RNA molecule. The second RNA molecule has the following formula: 5′-E′-X-A′-3′. [0073] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, C and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. The second RNA molecule is replicated by the RNA replicase under replicating conditions. [0074] Preferably, the sections A and E comprise at least one sequence that hybridizes to a third nucleic acid. Such third nucleic acid forms a hybridization product which hybridization product can be detected by known means. [0075] A second embodiment of the present invention features paired RNA molecules comprising a first RNA molecule. The first RNA molecule binds a target molecule and has the following formula: 5′-A-F-B-3′. [0076] And, the second RNA binds the target and has the following formula: 5′-D-H-E-3′ [0077] As used above, A is a section of the RNA molecule having 10-100,000 nucleotides which section is, with another RNA sequence, E, replicated by an RNA replicase. The letter “B” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence D, binds the target molecule under binding conditions. The letter “D” denotes a section of the RNA molecule having approximately 1 to 50000 nucleotides which section, with another sequence B, binds the target molecule under binding conditions. The sections B and D, in combination, comprise in total at least 10 nucleotides. The first RNA molecule, with sections B and D bound to target, is acted upon by the RNA replicase to form a third RNA molecule. The letter “F” denotes a section of the RNA molecule having has a hybridization sequence of 1-100, and more preferred, 1-50, and most preferred, 1-5 nucleotides which form a hybridization product with a complementary hybridization sequence of section H. The hybridization sequences of sections F and H preferably define a loop or hairpin at such times that section B and D are bound to target. In the absence of target, the hybridization sequences do not form a stable hybridization product. In the presence of the target, and the formation of a complex between sections B and D with the target, a hybridization product is formed that allows the RNA replicase to skip sections B and D and replicate sections A and E to form a third RNA molecule. The third RNA molecule has the following formula: 5′-E′-X-A′-3′. [0078] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, F, H and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. The third RNA molecule is replicated by the RNA replicase under replicating conditions. [0079] Preferably, the sections F and/or H have 1-10,000 nucleotides, and more preferred, 1-1000 nucleotides, and most preferred, 1-100 nucleotides which sequences define a stop sequence for the RNA replicase. [0080] A further embodiment of the present invention features a method of determining the presence or absence of a target molecule. The method comprises the steps of providing a first RNA molecule. The first RNA molecule is capable of binding to a target molecule and has the formula 5′-A-B-C-D-E-3′. [0081] The sections A, B, C, D and E are as previously described. The method further comprises the step of imposing binding conditions on a sample potentially containing target molecules in the presence of the first RNA molecule. In the presence of the target molecule, the first RNA molecule forms a target-first RNA molecule complex. [0082] The second RNA molecule has the formula: 5′-A′-X-E′-3′. [0083] The sections A′, X and E′ are as previously defined. It is believed that the RNA replicase skips sections B, C, and D as such sections are held, sterically hindered, by the target molecule. [0084] Further binding between sections B and D by short sequences adjacent sections A and E facilitate skipping by bringing the template sections in close proximity to each other. [0085] A second method comprises the steps of providing paired RNA molecules comprising a first RNA molecule and a second RNA molecule. The first RNA molecule is capable of binding to a target molecule and has the formula: 5′-A-F-B-3′. [0086] The second RNA molecule has the formula: 5′-D-H-E-3′ [0087] The sections A, B, D, E, F and H are as previously described. The method further comprises the step of imposing binding conditions on a sample potentially containing target molecules in the presence of the first RNA molecule and second RNA molecule. In the presence of the target molecule, the first RNA molecule and the second RNA molecule forms a target-first second RNA molecule complex. The method further comprises the step of imposing RNA replicase reaction conditions on the sample, in the presence of an RNA replicase, to form a third RNA molecule in the presence of target. The third RNA molecule has the formula: 5′-E′-X-A′-3′. [0088] As used above, E′ is the complement to E, and A′ is the complement to A. The letter “X” denotes the complement of parts of the sections B, F, H and D which may be replicated, or the letter denotes the direct bond between sections E′ and A′. [0089] Binding conditions are described by Gold L., Polisky B., Ulhlenbeck O, and Yarus M., (1995). In brief, binding conditions comprise room temperatures and 50 mM potassium acetate plus 50 mM Tris acetate, pH 7.5, 1 mM dithiothreitol [0090] The method further comprises the step of imposing RNA replicase reaction conditions on the sample, in the presence of an RNA replicase, to form a further RNA molecule in the presence of target. Reaction conditions for RNA replicases are known in the art. Q-beta replicase reactions are performed at 37° C. during 25-30 minutes in 50-ul reactions containing 88 mM Tris-HCL (pH 7.5), 12 mM MgCl 2 , 0.2 mM of each ribonucleoside triphosphate, 25 uCi of [alpha- 32 P]GTP, 90 pm/ml of Q-beta replicase, and 11.2 pm/ml of template RNA. [0091] The sample is monitored for the presence of the third RNA molecule or its complement, which presence or absence is indicative of the presence or absence of the target molecule. The detection of RNA replicase templates is well known. Propidium iodine is commonly used as an intercalating agent to create a color change. [0092] A further embodiment of the present invention comprises a kit for determining the presence or absence of a target molecule. The kit comprises a one or more reagents comprising a first RNA molecule for use with an RNA replicase. The first RNA molecule has the formula: 5′-A-B-C-D-E-3′. [0093] In the presence of target, the first and the second RNA molecules are capable of forming a target-first-RNA complex and in the presence of an RNA replicase, forming a second RNA molecule having the formula: 5′-A′-X-E′-3′. [0094] The letters A, B, C. D, E, A′ E′ and X are as previously described. The second RNA molecule is preferably capable of being replicated by Q-beta replicase. [0095] A second embodiment of the kit for determining the presence or absence of a target molecule features paired RNA molecules. The kit comprises a one or more reagents comprising a first RNA molecule and a second RNA molecule. The first RNA molecule has the formula: 5′-A-F-B-3′. [0096] The second RNA molecule has the formula: 5′-D-H-E-3′ [0097] In the presence of target, the first RNA molecule and the second RNA molecule are form a target-first-second RNA complex and in the presence of an RNA replicase, forming a third RNA molecule having the formula: 5′-A′-X-E′-3′. [0098] The letters A, B, C. D, E, ,F, H, A′ E′ and X are as previously described. The third RNA molecule is preferably capable of being replicated by Q-beta replicase. [0099] Turning now to FIG. 1, a kit, generally designated by the numeral 11 , is depicted. The kit 11 comprises the first RNA molecule or paired RNA molecules contained in one or more vials 13 , of which only one is shown, or means for making a first RNA molecule or paired RNA molecules. Preferably, the kit 11 has an RNA replicase illustrated as being contained in a second vial 15 , suitable buffers and reagents illustrated as being contained in a third vial 17 and instructions 19 . It is customary to package the elements of the kit 11 in suitable packaging such as box 21 . [0100] An embodiment of the present invention further comprises a method of making a first RNA molecule, wherein the first RNA molecule has the formula: 5′-A-B-C-D-E-3′. [0101] As used above, the letters A, B, C, D, and E are as previously described. The method comprises the step of combining a sample containing the target molecule with a library of RNA molecules having the formula: 5′-A-B′-C-D′-E-3′. [0102] to form a mixture of one or more target bound RNA molecules and one or more unbound RNA molecules. The letters B′ and D′ represent potential sections B and D. Next, primer nucleic acid corresponding to at least one section is added to the mixture with an enzyme capable of degrading the unbound RNA molecules. Next, bound RNA molecules are released from target and amplified to form an amplification product. Next, the RNA molecules comprising the amplification product having the formula: 5′-A-B′-C-D′-E-3′ [0103] are sequenced. Or, a cDNA formed and such cDNA cloned into suitable vectors. [0104] Preferably, the steps of forming a mixture, degrading unbound RNA molecules and amplifying the bound RNA molecules are repeated. [0105] Preferably, the sections B′ and D′ are randomized nucleotides. Or, in the alternative, are generated through in vitro selection. [0106] Preferably the step of degrading the unbound RNA molecules is performed in the presence of the enzyme reverse transcriptase. Methods and procedures for performing reverse transcriptase reactions are well known. [0107] An embodiment of the present invention further comprises a kit for performing performing the above method of identifying first and second RNA molecules. The kit 11 has been described with respect to FIG. 1. The kit 11 comprises one or more nucleic acid molecules having sections corresponding to the sections A, B′, C, D′, and E. Preferably, the kit comprises sections B′ and E′ as randomized nucleotide sequences. EXAMPLE 1 General Methods of Making Paired RNA Molecules [0108] To construct the paired RNA molecules for the target analyte with a known ligand, two sets of the complementary oligonucleotide are designed and synthesized on a DNA synthesizer. One set of oligonucleotides is dsDNA representing the 5′ part of the whole ligand. The other set of oligonucleotides is dsDNA representing the 3′ part of the same ligand. Both dsDNAs are designed with terminal restriction enzyme sites for cloning in the vector, and with additional nucleotides with lengths from one to ten nucleotides. These additional sequences are selected to define stop sequences and sections F and H of such paired RNA molecules. The first dsDNA has the following formula: 5′-M--N--O--P-3′. The second dsDNA has the following formula: 5′-P--R--S--T-3′, where M, P and T are restriction site linkers, O is sequences representing the 5′ segment of the ligand, R is sequences representing the 3′ segment of the ligand, and N and S are stop sequences. [0109] These two dsDNAs are cloned in a recombinant plasmid containing the T7 RNA promoter, followed immediately by inserting a Q-beta replicase template cDNA. A suitable cloning vector is disclosed in FIG. 2. Three unique restriction sites (M, P and T) for cloning dsDNA molecules are incorporated into the recombinant plasmid. One cloning site, M follows the T7RNA promoter immediately. The T cloning site is inserted into the end of the Q-beta replicase template, and the P site divides the template insert into two, 5′ and 3′, parts. Thus, the 5′ part of the Q-beta replicase template is flanked by M and P restriction sites and 3′ part of the template is flanked by P and T restriction sites. [0110] The composition of the insert in such recombinant plasmid will be: T7 promoter--M--Q-beta template--P--Q-beta template--T [0111] A second recombinant plasmid is prepared by replacing the 5′ part of the Q-beta replicase template cDNA situated between the M and P restriction sites with corresponding dsDNA representing the 5′ segment of the ligand. The combined insert of the second recombinant plasmid has the following formula: T7 promoter--M--N--P--Q-beta template--T [0112] A third recombinant plasmid is prepared by replacing the 3′ part of the Q-beta replicase template cDNA situated between the P and T restriction sites with corresponding dsDNA representing the 3′ segment of the ligand. The combined insert of the third recombinant plasmid has the formula: T7 promoter--M--Q-beta template--P--S--T. [0113] The second and third recombinant plasmids will be linearized by cleavage in the T restriction site, and the recombinant RNAs will be transcribed from each plasmid using the T7 RNA promoter. [0114] Two recombinant RNA transcripts are formed. [0115] The structure of the first detector-molecule is: 5′-A-F-B-3′. [0116] And the structure of the second detector-molecule is: 5′-D-H-E-3′. [0117] To form the single probe embodiment, essentially the same process is used, however, only one recombinant plasmid is formed encoding the entire first RNA molecule. [0118] Recombinant plasmids containing the template sequences with the inserted sequences are used to transform competent bacterial cells, and the transformed cells are grown in a culture. The cultured cells are harvested and lysed. The DNA plasmids are purified. The recombinant plasmids are cleaved with an appropriate restriction enzyme and the recombinant Q-beta replicase templates containing the inserts of the original DNA are transcribed into the RNA using T7 RNA promoter. All procedures are performed according to the standard protocols of J Sambrook, E F Fritsch and T Maniatis (1989) known to someone skilled in the field of molecular biology. EXAMPLE 2 Construction of RNA Molecules with MDV-1 Sequences and ATP Binding Sequences [0119] This example describes the construction of RNA molecules with MDV-1 sequences and ATP binding sequences. An oligoribonucleotide, aptamer ATP-40-1, with a high-affinity to ATP molecules was identified (Sassanfar and Szostak, 1993). The sequence encoding ATP-40-1 aptamer, with an XhoI cloning site incorporated at the termini, is set forth in Seq ID No 9 below: Seq ID No 9 5′- TCGA GGGTTGGGAAGAAACTGTGGCACTTCGGTGCCAGCAACCC-3′ 3′-CCCAACCCTTCTTTGACACCGTGAAGCCACGGTCGTTGGG AGCT-5′ [0120] Turning now to FIG. 3, the binding element of the original aptamer is composed of the 11-base consensus sequence and an unpaired G which is flanked by two base-paired stems. This aptamer is incorporated into plus-strand of the MDV-I RNA template using pT7MDV-1 recombinant plasmid with T7 RNA transcription promoter and standard molecular cloning procedures as depicted in FIG. 2(Sambrook et al., 1989). [0121] A computer analysis, with the program RNADRAW, suggested that the structural organization of the binding element of the original secondary structure of the ATP-40-1 aptamer remains intact when this aptamer fuses with plus-strand of Q-beta RNA templates. The secondary structures for ATP aptamer and for ATP-401/MDV-1 recombinant RNA as well as secondary structures of all further discussed RNA molecules were predicted by folding algorithms which showed only one of usually several alternative structures and RNA molecules of the same species with other structures might be present in a population. [0122] The ATP aptamer sequences do not affect MDV-I RNA's ability to be amplified by Q-beta replicase, and the ATP aptamer-insert propagated in the recombinant RNA continues to demonstrate a high level of affinity to the original ligand, ATP. A ‘short’ wild-type amplification product was generated by Q-beta replicase together with a ‘full length’ amplification product when a recombinant RNA was used as a template. Apparently, Q-beta replicase does not always faithfully amplify the whole recombinant template with the ATP aptamer insert, but occasionally, with a frequency between 20% and 50%, skipped an insert and generate a wild type template. [0123] Affinity of the synthesized recombinant template containing ATP specific RNA sequences to ATP was measured using the method for isocratic elution of labeled RNA from an ATP-agarose column (Sassanfar and Szostak, 1993). Nearly 100% of the recombinant RNA was collected from the 6B Sepharose column in the first two fractions. The same RNA, on the other hand, showed high affinity to the ATP-agarose. The elution rate slowed significantly after collecting the first four fractions. Addition of 4 mM ATP to the elution buffer increased the elution rate fourfold. This change in the elution rate could be explained by the competition between free ATP in the elution buffer and agarose-bound ATP for the ATP-binding insert in the recombinant RNA. Practically all of the labeled recombinant RNA used in this experiment was eluted with 3.5 ml of an elution buffer containing ATP. Completion of the elution was confirmed by treating the column with 10 mM EDTA. The lack of affinity of this recombinant MDV RNA to 6B Sepharose suggests that the affinity of this RNA to ATP-agarose is determined by the aptamer-insert, rather than by the flanking insert sequences of MDV RNA itself. Thus, two direct conclusions follow from these experiments. First, the ATP aptamer sequences do not affect MDV-I RNA's ability to be a template for Q-beta replicase. Secondly, the ATP aptamer-insert propagated in the recombinant RNA continues to demonstrate a high level of affinity to the original ligand, ATP. EXAMPLE 3 [0124] This example describes the design and a construction of paired RNA molecules that will be used for ATP. Such paired RNA molecules will not generate an amplification product separately or when they will be used together in the presence of Q-beta replicase, ribo-nucleotide mix and an appropriate buffer since neither of the recombinant RNA molecules, nor two of them together, have a full and an intact complement of the replicatable, plus-strand, MDV-1 template. [0125] The stability of such ternary complex formed in the presence of ATP is reinforced by a large number of paired nucleotides in RNA molecules. These regions of pairing will keep in close proximity two unbound terminal assembles of the paired RNA molecules as best seen in FIG. 4. [0126] Furthermore, one region of RNA/ATP ternary complex will be protected from to be ‘unzipped’ by Q-beta replicase during template's amplification and Q-beta replicase will be able to use Region 1 as a ‘bridge’ and to skip the whole insert with a rate of 20-50%. Therefore, Q-beta replicase will be able to produce a functional minus-strand wild type MDV-1 template. This minus-strand will then serve as a template for wild type plus-strand in further replication. The presence of two wild type, plus and minus-templates assure an exponential amplification of RNA. [0127] The sequence for the full length of the MDV-1 RNA is presented as Seq ID No 1. The coding DNA for this template was incorporated into the T7 MDV-1 plasmid depicted in FIG. 2. The bold letters in the MDV-1 RNA depict the cloning sites. MDV-1 RNA has the following cloning sites: PpuMI site (GGGACCC) at the 5′ end of the template followed the T7 RNA transcription promoter, Eco1471 (AGGCCU), Xho I (CUCGAG), Bgl II (AGAUCU) and Xba I (UCUAGA) represented a multicloning site in the middle of the molecule. Two cloning sites, Sma I (CCCGGG) and Eco RI (GAAUUC) are in the 3′ end of the molecule. [0128] Each recombinant RNA molecule will consist of two parts, sequences of ATP aptamer and of MDV-1 template. The nucleotide sequences for an original ATP-40-1 aptamer is set forth in Seq ID No. 9 (Sassanfar and Szostak, 1993). This sequence was modified in the following manner. An A-U pair was introduced into one double-stranded region and one of the G-C pair was substituted for a pair C-G in the same position. The terminal loop, which in an original aptamer was represented by four nucleotide, UUCG, were changed to ten nucleotides, AAAGAAUUGG. The first RNA molecule of the paired RNA molecules will have nucleotide sequence set forth in Seq ID No 10: Seq ID No. 10 5′ GGGGACCCCC CCGGAAGGGG GGGACGAGGU GCGGGCACCU UGUACGGGAG UUCGACCGUG ACGCAUAGC A GGaguuggga agaaacugug ggacuucgAA UU 3′ [0129] The capital letters depict the 5′ segment of MDV-1 template; the small bold letters depict the sequences of the ATP that will substitute a 3′ segment of the MDV-1 template and to be cloned between Eco 1471 and Eco RI cloning sites of the plasmid. [0130] The second recombinant RNA molecule will have nucleotide sequence set forth in Seq ID No. 11: Seq ID No. 11 5′-GGGGACCCCC CG GGguccca gcaacuCCU C GAGAUCUAGA GCACGGGCUA GCGCUUUCGC GCUCUCCCAG UGACGCCUCG UGAAGAGGCG CGACCUUCGU GCGUUUCGGC AACGCACGAG AACCGCCACG CUGCUUCGCA GCGUGGCUCC UUCGCGCAGC CCGCUGCGCG AGGUGACCCC CCGAAGGGGG GUUCCC-3′. [0131] The capital letters depict the 3′ segment of MDV-1 template; the small bold letters depict the sequences of the ATP that will substitute a 5′ segment of the MDV-1 template and to be cloned between Eco 1471 and PpuMI cloning sites of the plasmid. [0132] The construction of the recombinant RNA molecules is performed following standard cloning procedures. The synthesis of the designed recombinant RNAs is outlined in FIG. 5. The construction of the recombinant RNAs will start with the pT7 MDV-1 recombinant plasmid containing T7 RNA polymerase promoter, and DNA inserts representing MDV-1 template and restriction sites, described above. The plasmid DNA will be double-digested either with PpuMI and Eco 1471 or with Eco 1471 and Eco RI restriction enzymes and purified from the excised fragments. The linearized cloning vectors will be annealed with synthetic cDNAs representing ATP-specific RNA sequences with appropriate cohesive ends and ligated with T4DNA ligase. Recombinant plasmids with desired cDNA inserts will be amplified and then transcribed using T7RNA polymerase promoter following the standard procedures (Sambrook et al., 1989). The RNA transcripts will be purified either by polyacrylamide gel (PAGE) or commercially available RNA purification kits. [0133] We anticipate that paired RNA molecules together with ATP will form a ternary structure, where the two RNA molecules will acquire a conformation similar to the native ATP aptamer, i.e. an asymmetrical bulge flanked by two double-stranded segments. The hybridized recombinant RNAs will have a terminal gap between them that will prevent replication. However, the interaction of an ATP molecule with two recombinant RNA molecules will be strong enough to secure the stability of the double-stranded regions and to promote synthesis of a functional wild type MDV-1 template under Q-beta replicase reaction conditions. The wild-type MDV-1 template is the amplification product of interest. [0134] The reaction is performed at 37° C. in solutions containing Tris-HCl (pH 7.5), a mixture of ribonucleoside triphosphate, appropriate Mg- and Na-salts, and Q-beta replicase enzyme. The concentrations of reaction mix components, such as triphosphates, MgCl 2 and NaCl, template/Q-beta replicase molar ratios are varied to achieve optimal conditions under which the maximal yield of the minus-strand templates and amplified product will be reached. The actual number of templates in the reaction can be estimated by adding the sample to a standardized reaction mixture and measuring the time required to produce a signal with an intercalating fluorescent dye. The response time is universally proportional to the log of the number of template molecules present in the sample (Lomeli et al., 1989). [0135] There are several nucleotide modifications for fluorimetric assays that can be easily used by Q-beta replicase enzyme for RNA amplifications. One such compound is 8-azidoadenosine 5′-triphosphate (8-azido ATP), which could be incorporated into the replicated RNA and is useful in reactions with different fluorochromes (Czarnecki et al., 1979). Another modified nucleotide is 4-thiouridine 5′-diphosphate (4-thio UTP) which also could be incorporated into replicated RNA by Q-beta replicase. Consequently, 7-fluoro-2,1,3-benz-oxadiazole-4-sulfonamide might be used as a reagent for fluorometric identification of the thiol group in the incorporated thionucleotides (Toyooka and Imai, 1984). The amplified recombinant RNA templates can be also identified and quantified by various easily available fluorescent dyes, such as ethidium bromide or RiboGreen (Molecular Probes Inc.), which produce a fluorescent signal upon intercalation into base-paired double stranded regions of the amplified RNA. [0136] For quantification of the template in the reaction mix, 5-ul aliquots are removed at 5 min intervals and mixed with ice-cold 90% formamide containing 50 mM Tris-borate (pH 8.2), 2 mM EDTA, 1 ug/ml carrier tRNA. From this mixture, from seven to 15 ul are applied directly onto magnesium-containing PAGE for visual analysis of the amplification product. For fluorescent analysis, the amplification reaction is filtered through DE81 (ion exchange) filters. The filters is washed two times with 5 ml buffer containing 50 mM Tris-HCl ph 7.5, 100 mM NaCl, 2 mM MgCl 2 and 1 mM EDTA. The bound material is eluted with 5 ml buffer containing 50 mM Tris-HCl ph 7.5, 500 mM NaCl, 2 mM MgCl 2 and 1 mM EDTA and collected. The filters, eluates and washing buffer are collected and fluorimetrically assayed. Aliquots of each amplification reaction are taken at 1 min intervals, and the RNA in each aliquot assessed using the fluorescence of the amplified detector molecules by photography over an ultraviolet light box, or measured in a fluorometer. EXAMPLE 4 [0137] This example describes paired RNA molecules composed of Sarcin/Ricin and Rev protein specific sequences and RQT template sequences. The sequences specific for Sarcin and Ricin allow the formation of stop sequences and allow further stabilization of the tertiary complex. That is, the paired RNA molecule have two, tandemly-arranged RNA aptamer sequences. Each aptamer sequence has affinity to a different target, either Rev protien or Sarcin/Ricin. The paired RNA detector molecules with two recognition sites will bind with two targeted molecules and will form a quadruple complex of two RNAs and two targets. Such quadruple RNA/target complex will be more rigid structurally than a ‘two RNAs/single target’ ternary complex and, thus, will reinforce the stability of the double stranded regions. The double stranded regions and the stable ternary complex will facilitate the generation of a wild type minus-strand replicatable template. [0138] The recombinant pT7 RQT plasmid with DNA encoding RQT RNA, depicted in FIG. 6, was constructed in our lab. The RNA sequence of RQT RNA is set forth in Seq ID No. 12 as follows: Seq ID No. 12 5′-GGGGUUUCCA ACCGGAAUUU GAGGGAUGCC UAGGCAUCCC CCGUGCGUCC CUUUACGAGG GAUUGUCGAC UCUAGAGGAU CCGGUACC UG AGGGAUGCCU AGGCAUCCCC GCGCGCCGGU UUCGGACCUC CAGUGCGUGU UACCGCACUG UCGACCC-3′. [0139] The bold letters in the previous sequence depict three cloning sites XbaI, Bam HI and KpnI. [0140] The Sarcin/Ricin (S/R) specific region of the above sequence includes a near universal sequence for all of 23S rRNA sequence. This region comprises 12 ribonucleotides with a define secondary structure that appeared as a single terminal loop (Munishkin and Wool, 1997. Treatment of this oligonucleotide with low concentrations of alpha-Sarcin or Restrictocin generated two fragments as a result of the cleavage of the oligonucleotide by this protein in a specific site between G and A nucleotides (Wool, 1997 and Related Work). The same domain of 28S rRNA is a target for another, more notorious, toxin--ricin. Ricin, however, inactivates ribosomes by depurination of the A residue, which is upstream and next to the alpha-Sarcin target site (Marchant and Hartley, 1995). Ribosomes are extremely sensitive to the toxins. The K d s for the binding of the sarcin or ricin toxin to the S/R oligonucleotide are in the range of 10 −8 M (Wool, 1997). [0141] Human Immunodeficiency Virus type-1 Rev protein binds with high affinity to a bulge structure located within the Rev-response element (RRE) RNA, Rev protein-specific ligand RBC5L. The smallest oligoribonucleotide able to bind Rev protein with 1-to-1 stoichiometry and with high affinity (K d s of approximately 5 nM) carries the bulge and two sets of four flanking base pairs. The bulge structure contains a specific configuration of non-Watson-Crick G:G and G:A base pairs and demonstrates high affinity recognition of Rev protein by hydrogen bonding to the functional groups in the major groove of the Rev binding element. Introducing truncation and base pair modifications of the double stranded regions that flank the bulge did not affect the affinity or specificity of the original ligand, as long as the nucleotide sequence of the bulge itself was not changed. [0142] A recombinant RQT template with two heterologous RNA inserts, Rev protein-specific RNA sequences and R/S rRNA domain, organized in a tandem fashion was made. Using the ability of alpha-Sarcin and Restrictocin to cleave the Sarcin domain RNA between G and A nucleotides we generated two RNA molecules. A first RNA molecule has nucleotide sequence set forth in Seq ID No. 13: Seq ID No. 13 5′-GGGGUUUCCA ACCGGAAUUU GAGGGAUGCC UAGGCAUCCC CCGUGCGUCC CUUUACGAGG GAUUGUCGAC UCUAGucgac gucugggcga aaa -3′ [0143] The 5′ portion of the first RNA molecule corresponds to RQT template sequences set forth in Seq ID No. 4. The sequence gucugggcg corresponds to one half of the Rev-specific ligand. The sequence uaguacgag corresponds to a portion of the Sarcin specific RNA domain. [0144] A second RNA molecule has a sequence set forth in Seq ID. No. 14: 5′- aggacc uuuu cgguacagac GGUACC UGAG GGAUGCCUAG GCAUCCCCGC GCGCCGGUUU CGGACCUCCA GUGCGUGUUA CCGCACUGUC GACCC-3′ [0145] The 3′ portion of the second RNA molecule corresponds to RQT template sequences set forth in Seq ID No. 5. The sequence aggacc corresponds to a portion of the Sarcin-specific domain. The sequence cgguacagac corresponds to one half of the Rev-specific ligand. These two recombinant RNA molecules can be used as paired RNA molecules for the detection of one of the cytotoxins, such as Sarcin, Ricin or Restrictocin, in the presence of Rev protein, in a sample. [0146] Treatment of the recombinant RQT template that incorporates Rev protein-specific RNA sequences and alpha-Sarcin domain synthetic nucleotides with different concentrations of Sarcin or Restrictocin showed that almost a perfect cleavage of the recombinant template with a production of two RNA fragments, with expected sizes of 99 nt and 103 nt. About 85% of the substrate was cleaved with a single cut of either enzyme at concentration of 25 ug/ml (14.7×10 −7 M). Higher concentrations of Sarcin or Restrictocin led to non-specific cleavage of the recombinant RTQ template in numerous sites. Similar results were reported when a synthetic 35-mer oligoribonucleotide with nucleotide sequences and the secondary structure of the Sarcin domain was treated with Sarcin (Wool, 1997). The two recombinant RNAs generated as a result of the Sarcin or Restrictocin treatments are purified, either by polyacrylamide gel (PAGE) or commercially available RNA purification kits. [0147] RNA duplex formed as a result of hybidization of the constructed two recombinant RNA molecules is structured in the whole length of the RQT sequences and unstructured in the binding with the Rev protein and Sarcin targets region. Hybridization of two RNA molecules is performed in a standard renaturation buffer containing 10 mM Tris-HCl, pH 7.6, 50 mM NaCl and 10 mM MgCl 2 with final concentration of RNA molecules in a range of 30 ng/ul. The solution with RNA molecules is boiled for 2 min and then chilled to room temperature. The optimal concentration of two RNA molecules and their molar ratios are determined empirically. [0148] The RNA complex composed of two hybridized RNA molecules is with either Rev protein or Sarcin and placed under binding conditions. An annealing reaction of RTQ Rev/Sar RNA for Rev protein is performed in 10 mM Hepes/KOH buffer, pH 7.8, containing 100 mM KCl, 2 mM MgCl 2 , 0.5 mM EDTA, 1 mM DTT and 10% Glycerol. An annealing reaction of RQT Rev/Sar RNA with Sarcin and Restrictocin is performed in reaction mix containing 10 mM Tris-HCl buffer, pH 7.6, 50 mM KCl and 4 mM EDTA. The binding complex of Rev protein and hybridized paired RNA molecules will be separated from the unbound molecules by filtration through nitrocellulose membrane filters (Tuerk and Gold, 1990). [0149] The complex is then subjected to Q-beta replicase reaction conditions. The sample is monitored for the presence of wild type templates which are indicative that the enzyme has skipped the bound parts of the molecule. EXAMPLE 5 [0150] This example features the construction of paired RNA molecules using Sarcin or Restrictocin as an agent that will cut a single recombinant RNA molecules into two parts. This method has the following major steps: (1) a cloning a single DNA into an available recombinant plasmid encoding Q-beta template sequences, (2) a transcription of the total length of the recombinant template RNA with the proper heterologous inserts, and (3) cleavage of the recombinant template into two parts using appropriate agent. [0151] This simple protocol can be tailored to construct paired RNA molecules to identify any non-nucleic acid target that demonstrates affinity to the particular RNA sequence. Cleavage of a single RNA into first and second paired RNA molecule can be performed with some ribozymes or oligozymes. [0152] Using standard cloning procedures, dsDNA represented Rev/Sarcin specific RNA sequences is cloned into pT7RQT plasmid using Kpn I/Xba I as a cloning sites. The new recombinant plasmid is linearized with Sma I restriction enzyme. Recombinant RNA that combined RQT, S/R and Rev protein specific RNA sequences, RQT Rev/Sar RNA, is transcribed using T7 RNA transcription promoter. The RNA sequences of the recombinant RQT RNA template with Rev-Sarcin specific insert are set forth in Seq ID No. 15: Seq ID No. 15 5′-GGGGUUUCCA ACCGGAAUUU GAGGGAUGCC UAGGCAUCCC CCGUGCGUCC CUUUACGAGG GAUUGUCGAC UCUAGucgac gucugggcga aaa auguacg agaggacc uu uucgguacag acGGUACC UG AGGGAUGCCU AGGCAUCCCC GCGCGCCGGU IJUCGGACCUC CAGUGCGUGU UACCGCACUG UCGACCC-3′. [0153] The capital letters in the sequence above depict the nucleotides of the RQT templates, with the bold capital letters indicating the restriction sites. The small bold letters depict the Rev protein. The small, bold italic letters depict Sarcin specific RNA sequences. The Sarcin specific sequences are positioned within the sequences associated with Rev protein specific sequences. The combined Rev- and Sarcin-specific sequences is modified slightly from those reported earlier by eliminating some paired nucleotides and introducing a- and u-tetramers and UCGAC nucleotides to promote proper orientation as suggested by computer modeling. Both inserts are recognizable in the sense such molecules exhibit binding and/or are acted upon by the corresponding Rev protein, Sarcin or Restrictocin molecules. [0154] Annealing of RTQ Rev/Sar with Rev protein is performed in 10 mM Hepes/KOH buffer, pH 7.8, containing 100 mM KCl, 2 mM MgCl 2 , 0.5 mM EDTA, 1 mM DTT and 10% Glycerol. A gel mobilty shift assays suggests that RBC5L RNA (control aptamer) was found to form a stable ribonucleoprotein complex in an excess of the Rev protein. The Rev protein specific sequences incorporated into the RQT template continue to recognize the target Rev protein. [0155] Treatment of RQT Rev/Sar RNA with Sarcin and Restrictocin was performed in a reaction mix containing 10 mM Tris-HCl buffer, pH 7.6, 50 mM KCl and 4 mM EDTA. The same amount of internally 32 P-labeled RQT Rev/Sar RNA was treated with Sarcin or Restrictocin in concentrations of 2, 10 and 25 ug/ml. Products of the reaction were tested on 12% denatured PAGE with 7M Urea. The data suggest the amount of two RNA fragments of 95 and 102 nt is increased with the increase of the concentration of the either cytotoxin. The recombinant template is subjected to amplification by Q-beta replicase to produce a wild-type amplification product. [0156] References Cited [0157] U.S. Patent Documents [0158] Cech T R., Murphy F L., Zaug A J., Grosshans C., 1992. RNA ribozyme restriction endonucleases and methods. U.S Pat. No. 5,116,742 [0159] Gold L. and C. Tuerk. 1995. Nucleic Acid Ligands. U.S. Pat. No. 5,475,096 [0160] Gold L. and S. Rinquist. 1996. Systematic Evolution of Ligands by Exponential Enrichment: Solution SELEX. U.S. Pat. No. 5,567,588. [0161] Hazeloff J P., Gerlach W L., Jennings P A., Cameron F H. 1993. Ribozymes. U.S. Pat. No. 5,254,678. [0162] Martinelli R A., Donahue J J. and Unger T. 1995. Amplification of Midivariant DNA Templates. U.S. Pat. No. 5,407,798 [0163] Roberson H D., and Goldberg A R., 1993. Ribozyme Composition and Methods for Use U.S. Pat. No. 5,225,337 [0164] Other Publications [0165] Axelrod V A., Brown E., Priano C. and Mills D R. 1991. Virology, 184, 595-608 [0166] Bock et al., 1992, Bock L C., Griffin L C., Lathman J A., Vermaas E H. and Toole J J. 1992. Nature. 355, 564-566. [0167] Dobkin C., Mills D R., Kramer F R. and Spiegelman S. 1979. Biochemistry, 18, 2038-2044. [0168] Engler M J. and Richardson C C. 1982. The enzymes. Academic Press, Inc. vol XV. 3-29. [0169] Fernandez A., 1991. Z. Naturforsch C. 46, 656-662. [0170] Gold L., Polisky B., Uhlenbeck O, and Yarus M. 1995. Ann. Rev. Biochem. 64, 763-797. [0171] Joyce, G F. 1989. Gene, 82, 83-87. [0172] Kaufmann G., Klein T. and Littauer U Z. 1974. FEBS Lett. 46, 271-275. [0173] Klug S J. and Famulok M. 1994. Mol. Biol. Rep., 20, 97-107 [0174] Kubik M F., Stephens A W., Schneider D., Marlar R A. and Tasset D. 1994. Nucleic Acid Res., 22, 2619-2626. [0175] Leis J., Silber R., Malathi V G. and Hurwitz J. 1972. “Advances in the Biosciences” (G. Raspe, ed) Pergamon, New York. vol. VIII, 117 [0176] Lizardi P M., Guerra C E., Lomeli H., Tussie-Luna I. and Kramer F R. 1988. Biotechnology, 6, 1197-1202. [0177] Meselson M. and Yuang R. 1968. Nature, 217, 1110-1114 [0178] Mullis K B, Faloona F, Schraft, Saiki R K, Horn G and Erlich H A. 1986. CSH Symp. Quant Biol., 51, 263-273 [0179] Munishkin A V., Voronin L A., Ugarov V I., Bondareva L A., Chetverina H V. and Chetverin A B. 1991. J. Mol. Biol. 221, 463-472. [0180] Nakamura R M. 1993. College of American Pathologists Conference XXIV on Molecular Pathology: Introduction. Ach. Path. Lab. Med., 117, 445-492 [0181] Pieken W A., Olsen D B., Bensler F., Aurup H. and Eckstein F. 1991. Science. 253, 314-317. [0182] Priano C., Kramer F R and Mills D R. 1987. Cold Spring Harbor Symp. Quant. Biol. 52, 321-330. [0183] Pritchard C G. and Stefano J E. 1990 Ann. Biol. Clin. 48, 492-497. [0184] Qi An, Buxton D, Hendricks A, Robinson L, Shah J, Ling Lu, Vera-Garcia V, King V and Olive M D. 1995. J. Clin. Microbiol., 33, 860-867 [0185] Saiki R K, Scharft S, Faloona F et al., 1985. Science., 230, 1350-1354. [0186] Sambrook J., Fritsch E F and T. Maniatis. 1989. Molecular Cloning. Cold Spring Harbor Laboratory Press. [0187] Schneider D J., Feigon J., Hostomsky Z. and Gold L. 1995. Biochemistry. 34, 9599-9610. [0188] Silber R. Malathi V G. and Hurwitz J. 1972. Proc. Natl. Acad. Sci. USA 69, 3009-3013 [0189] Southern E, 1975. J. Mol. Biol., 98, 503-517. [0190] Sugino A., Goodman H M., Heyneker H L., Shine J., Boyer H M. and Cozzarelli N R. 1977. J. Biol.Chem. 252, 3987-3987 [0191] Tuerk C. and Gold L. 1990. Science. 249.505-510. [0192] Tyagi S., Landergen U., Tazi M., Lizardi P M. and Kramer F R. 1996. Proc. Natl. Acad. Sci. USA. 93, 5395-5400. [0193] Rys P N and Persing D H. 1993. J Clin Microbiol., 31, 2356-2360. [0194] Saiki R K. 1990. PCR Protocols: a Guide to Methods and Applications. M. A. Innis, D. H. Gelfand. J. J. Sninsky and T. J. White eds. (New York: Academic Press, Inc.), 13-20 Saiki R K, ScharftS, Faloona F et al., 1985. Science., 230, 1350-1354. [0195] Sambrook J., Fritsch E F and T. Maniatis. 1989. Molecular Cloning. Cold Spring Harbor Laboratory Press. [0196] Schneider D J., Feigon J., Hostomsky Z. and Gold L. 1995. Biochemistry. 34, 9599-9610. [0197] Silber R. Malathi V G. and Hurwitz J. 1972. Proc. Natl. Acad. Sci. USA 69, 3009-3013 [0198] Southern E, 1975. J. Mol. Biol., 98, 503-517. [0199] Sugino A., Goodman H M., Heyneker H L., Shine J., Boyer H M. and Cozzarelli N R. 1977. J. Biol.Chem. 252, 3987-3987 [0200] Tuerk C. and Gold L. 1990. Science. 249. 505-510. [0201] Tyagi S., Landergen U., Tazi M., Lizardi P M. and Kramer F R. 1996. Proc. Natl. Acad. Sci. USA. 93, 5395-5400. [0202] Uhlenbeck O C, and Gumport R D. 1982. The enzymes. Academic Press, Inc. vol XV. 31-58. [0203] Uhlenbeck O C. 1983. TIBS. March, 94-96. [0204] Verma I M. 1991. The Enzymes, The Academic Press, vol XIV, 87. [0205] Weissmann C., Feix G. and Slor H. 1968. Cold Spring Harbor Symp. Quany. Biol. 33, 83-100. [0206] Wu Y., Zhang D Y. and Kramer F R. 1992. Proc. Natl. Acad. Sci. USA. 89, 11769-11773. [0207] Ziff E B. and Evans R M. 1978. Cell 15, 1463-1475. 1 15 1 250 RNA Q-beta bacteriophage 1 ggggaccccc ccggaagggg gggacgaggu gcgggcaccu uguacgggag uucgaccgug 60 acgcauagca ggccucgaga ucuagagcac gggcuagcgc uuucgcgcuc ucccagguga 120 cgccucguga agaggcgcga ccucgugcgu uucggcaacg cacgagaacc gccacgcugc 180 uucgcagcgu ggcuccuucg cgcagcccgc ugcgcgaggu gaccccccga agggggguuc 240 ccgggaauuc 250 2 76 RNA Q-beta bacteriophage 2 ggggaccccc ccggaagggg gggacgaggu gcgggcaccu uguacgggag uucgaccgug 60 acgcauagca ggaauu 76 3 184 RNA Q-beta bacteriophage 3 ggggaccccc cgggccucga gaucuagagc acgggcuagc gcuuucgcgc ucucccagug 60 acgccucgug aagaggcgcg accuucgugc guuucggcaa cgcacgagaa ccgccacgcu 120 gcuucgcagc guggcuccuu cgcgcagccc gcugcgcgag gugacccccc gaaggggggu 180 uccc 184 4 80 RNA Artificial Sequence Description of Artificial SequenceDERIVED FROM REACTION PRODUCT OF Q-BETA REPLICASE 4 gggguuucca accggaauuu gagggaugcc uaggcauccc ccgugcgucc cuuuacgagg 60 gauugucgac ucuagucgac 80 5 75 RNA Artificial Sequence Description of Artificial SequenceDERIVED FROM REACTION PRODUCT OF Q-BETA REPLICASE 5 gguaccugag ggaugccuag gcauccccgc gcgccgguuu cggaccucca gugcguguua 60 ccgcacuguc gaccc 75 6 26 RNA Artificial Sequence Description of Artificial Sequence APTOMER FOR ATP 6 aguugggaag aaacuguggg acuucg 26 7 12 RNA Artificial Sequence Description of Artificial Sequence APTOMER FOR ATP 7 gucccagcaa cu 12 8 15 RNA Artificial Sequence Description of Artificial SequenceSARCIN RECOGNITION 8 auguacgaga ggacc 15 9 70 RNA Artificial Sequence Description of Artificial Sequence APTOMER FOR ATP 9 cgagggggga agaaacgggc accgggccag caacccccca accccgacac cggaagccac 60 ggcggggagc 70 10 102 RNA Artificial Sequence Description of Artificial SequenceCOMBINED MDV-1 AND ATP APTOMER 10 ggggaccccc ccggaagggg gggacgaggu gcgggcaccu uguacgggag uucgaccgug 60 acgcauagca ggaguuggga agaaacugug ggacuucgaa uu 102 11 196 RNA Artificial Sequence Description of Artificial Sequence COMBINED MDV-1 AND ATP APTOMER 11 ggggaccccc cgggguccca gcaacuccuc gagaucuaga gcacgggcua gcgcuuucgc 60 gcucucccag ugacgccucg ugaagaggcg cgaccuucgu gcguuucggc aacgcacgag 120 aaccgccacg cugcuucgca gcguggcucc uucgcgcagc ccgcugcgcg aggugacccc 180 ccgaaggggg guuccc 196 12 157 RNA Artificial Sequence Description of Artificial SequenceRQT RNA WITH CLONING SITES 12 gggguuucca accggaauuu gagggaugcc uaggcauccc ccgugcgucc cuuuacgagg 60 gauugucgac ucuagaggau ccgguaccug agggaugccu aggcaucccc gcgcgccggu 120 uucggaccuc cagugcgugu uaccgcacug ucgaccc 157 13 102 RNA Artificial Sequence Description of Artificial SequenceRQT WITH REV AND SARCIN RECOGNITION SITES 13 gggguuucca accggaauuu gagggaugcc uaggcauccc ccgugcgucc cuuuacgagg 60 gauugucgac ucuagucgac gucugggcga aaaauguacg ag 102 14 95 RNA Artificial Sequence Description of Artificial SequenceRQT WITH REV AND SARCIN RECOGNITION SITES 14 aggaccuuuu cgguacagac gguaccugag ggaugccuag gcauccccgc gcgccgguuu 60 cggaccucca gugcguguua ccgcacuguc gaccc 95 15 197 RNA Artificial Sequence Description of Artificial Sequence RQT WITH SARCIN AND REV RECOGNITION SITES 15 gggguuucca accggaauuu gagggaugcc uaggcauccc ccgugcgucc cuuuacgagg 60 gauugucgac ucuagucgac gucugggcga aaaauguacg agaggaccuu uucgguacag 120 acgguaccug agggaugccu aggcaucccc gcgcgccggu uucggaccuc cagugcgugu 180 uaccgcacug ucgaccc 197

The present invention is directed to methods, compositions, kits and apparatus to identify and detect the presence or absence of target analytes. The embodiments of the present invention have utility in medical diagnosis and analysis of various chemical compounds in specimens and samples, as well as the design of test kits and apparatus for implementing such methods.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator. Semiconductor laser diodes which are used as transmitting elements in optical telecommunications must simultaneously fulfill a plurality of requirements which can, however, be optimized only in dependence on one another. For example, in the case of a direct modulation in a semiconductor laser diode, only a high current density or a high internal light intensity ensures a fast intrinsic modulability, but at the same time parasitic effects such as parasitic resistances, parasitic capacitances and parasitic inductances in the supply leads should be minimized, and the internal heating of the component should be limited. This can be achieved with the aid of an optical modulator driven separately electrically. Specifically in the case of a laser structure in which the resonator fixes the wavelength—for example in the case of a d istributed f eed b ack laser (DFB laser) or a v ertical- c avity s urface- e mitting l aser (VCSEL), the relative displacement of the laser wavelength and the absorption edge with temperature mostly ensures a narrow temperature window in which the modulation principle functions. It is therefore desirable to have a modulator which can be used in a wide spectral and temperature range. Moreover, it is also desirable for the transmission of digital signals likewise to have a digital modulation principle in which the optical modulator can assume only two states, for example absorbing (“off” state) and poorly or non-absorbing (“on” state), and these states cannot be influenced by the preceding signal sequence. If, for example, the active surface of the laser is reduced, a high current density and a fast modulability together with a limited thermal heating of the laser are achieved with small currents through the active surface. At the same time, however, the series resistance grows because of the current constriction. In conjunction with existing non-scalable capacitances at the connecting contacts (pads) and in the driver circuit, this leads to an undesired additional RC limitation of the modulability. An external modulator is normally used, first and foremost, in telecommunications applications. However, this is expensive in the datacom sector and would precisely nullify the advantage of an inexpensive laser diode, for example a vertical emitter. By contrast, because of the required compactness, in the case of integrated modulators use is predominantly made of direct modulation of the imaginary part of the refractive index in so-called electroabsorption modulators. 2. Description of the Related Prior Art Laser diodes with a monolithically integrated electroabsorption modulator are already known from the prior art, for example from [1], [2] or [3]. In this case, for example, the Quantum Confined Stark Effect, shortened below to QCSE, is utilized in order to displace the absorption edge in the modulator and thereby to switch the modulator to and from between the “off” state and the “on” state. With such a modulator it is only the efficiency of the charge carrier removal, that is to say the charge carrier emission from the quantum wells and the drift over the field region, which limits the intrinsic speed by analogy with photodetectors. It is disclosed in [4] in this context that filling effects and changes in the local electric field should be avoided because of their strong effects on the optical properties. A substantial disadvantage of this modulation principle is, however, the limited effect of the displacement of the quantum well band gap or of the fundamental exciton absorption concerned as a function of the applied field. In the case of a typical VCSEL structure, which should be operated uncooled between 0° C. and 85° C., the relative displacement between maximum gain and emission energy is approximately 30 meV. Moreover, a deviation of up to ±10 meV between laser resonance and modulator band gap should also be permitted in order to be able to compensate layer thickness tolerances between the individual components. In order in an appropriate modulator quantum well to adapt only the band gap or fundamental exciton absorption line by the overall amount set forth above in relation to the resonator wavelength, an absorption edge displacement of 50 meV will already need to be achieved via the change in bias. According to [5], the realistically achievable displacement is approximately half as large. The fields required for this purpose of the level of a few 10 5 V/m would lead to dissociation of the excitons, and the modulation characteristic would not be uniform in the overall operating range. In addition, for a given voltage range the large field region in the system limits the length of the intrinsic region and thus the minimization of the capacitance. Moreover, nonlinear effects such as impact ionization are also to be considered. For GaAs, the ionization coefficient for electrons is just 10 4 /cm at 250 kV/cm. Consequently, electroabsorption modulators which use the QCSE can be used without a problem only in temperature-controlled systems with defined detuning of the resonator wavelength on the one hand, and between the gain and absorption spectra of the active regions, on the other hand. By contrast with the QCSE modulator, in the case of a modulator which operates with charge carrier filling, when it is switched into the transparent state, the charge carriers are firstly transported to the quantum well and then captured there. Consequently, in the case of this modulator type both the charge carrier emission process and the charge carrier capture process form the fundamental speed limitations. The charge carrier capture in quantum wells with good charge carrier inclusion proceeds yet more quickly than the charge carrier emission and is of the order of magnitude of 10 −12 in accordance with [6]. Neither capture nor emission times would be a fundamental limitation for targeted modulation frequencies up to 40 GHz, since these can be kept shorter than 5 ps by means of a favorable quantum well design and, in the case of the emission time, by means of correspondingly high fields. However, this holds only as long as the charge carrier recombination which is slower by several orders of magnitude is not used for switching, and as long as the charge carrier transport by means of drift or diffusion is fast enough. In the case of a pin quantum well structure being forwardly polarized, transport on the undoped barriers at low carrier densities essentially only takes place by means of diffusion. A pin quantum well structure is to be understood in this case as a quantum well structure of a strongly doped p-region, a strongly doped n-region and an intrinsic region lying therebetween. The diffusion time for holes is determined in accordance with τ diff =L i 2 /4D h . In the case of an assumed spacing of the quantum well from the p-doped region of L i =100 nm and a diffusion constant at room temperature of D h =kTμ h /q=5 cm 2 /s for Al 0.2 Ga 0.8 As, this results in such a case in a transport time of approximately 5 ps, but this grows quadratically with the diffusion length. Depending on the quantum well design and doping profile, thus, it is either the transport time or the physical capture time which predominates. If the undoped diffusion regions are reduced, the capacitance is increased, however. This has a disadvantageous effect on the modulation rate if the charge carriers need to be removed from the quantum well again not, as in the laser, already by means of stimulated recombination, but only by means of a change in the external voltage. In this case, the space charge capacitance in series with the bulk resistance leads to an RC limitation of the modulation bandwidth. The intrinsic series resistance is determined chiefly by the p-doped lead layer on the basis of the low hole mobility in semiconductor materials. Consequently, it would be desirable to have a concept which permits optimum setting of capacitance, transport times and bulk resistance depending on semiconductor material used, modulated design and parasiticities of the lead and/or drive. Thus, the bulk resistance can be substantially reduced, for example, when exclusively n-doped lead layers are used. Such a modulation principle, which comprises nipin-structures (structures composed of a layer stack of n -doped layer, i ntrinsic layer, p -doped layer, i ntrinsic layer and n-doped layer) and operates chiefly with electron filling into a quantum well from a neighboring n -doped heterobarrier (reservoir), has become known under the designation BRAQWET ( B arrier R eservoir A nd Q uantum- W ell E lectron- T ransfer) (compare [7]). In accordance with the BRAQWET, the so-called Burstein-Moss-effect is used, that is to say the reduction of the absorption by filling only one sort of charge carrier into the quantum well. Since the state density of the conduction band is normally substantially smaller than that of the valence band, the quantum well is filled with electrons. Consequently, degeneracy is achieved as early as with a low charge carrier density of approximately 2×10 18 cm −3 , and absorption saturation in the region of the band edge, on the basis of the Pauli exclusion principle. The advantage is that the absorption profile can be displaced both in frequency by means of the QCSE, and also in amplitude by means of filling. Consequently, an increase in the field leads in both cases to increasing the absorption. The electron transport times are generally negligible. However, the structures have some disadvantages. Because of the need to optimize electron filling, operations should be conducted with sufficiently high diffusion barriers relative to the electron reservoir. In accordance with [8], this in turn limits the electron emission rate upon switching over to maximum absorption. The effective barrier height is lowered with high fields, if appropriate. Furthermore, it is known in accordance with the prior art to render the reservoir barrier continuous, it thereby being possible to shorten the electron emission times virtually at will. However, in principle this is done at the cost of the electron inclusion. However, the pump-probe measurements published in [9] exhibit no worsening in the electrooptical properties. In the case of optical excitation, however, long effective hole emission times were observed in the nanosecond region. The barrier height on the extraction side for holes is very high in BRAQWETs, in order to configure the electron filling efficiently and with a low leakage current. The negative effect of the field shielding of remaining holes is not yet explained in this case. In general, it is either possible for a given voltage shift to maximize the absorption shift into a larger spectral range, or to optimize rate. Furthermore, in the case of unipolar filling the state of transparency cannot be completely achieved, and the absorption shift is still a function of temperature, although the spectral dependence of the absorption shift is already reduced by contrast with pure QCSE modulators. In addition, only a quantum well can be filled efficiently in unipolar fashion per npn region. Consequently, several absorption regions are mostly arranged one above another. In accordance with [7], this multiplies the voltage requirement. During a lengthy “on” state (absorption minimum in the modulator), by contrast, a state of transparency is achieved nevertheless because of the generation of holes on the basis of the non-vanishing absorption. On the one hand, the modulation depth is thereby a function of the bit sequence, while on the other hand the plasma then produced must be removed from the pn junction or the quantum well. This does lead, finally, to an increased space charge capacitance. Consequently, the respective other charge carrier type, which necessarily arises upon absorption, should be efficiently swept out even in the case of a theoretically pure absorber operating in a unipolar fashion. Disclosed in [10] is an optical electroabsorption modulator in which a first upper cladding layer and a second upper cladding layer are provided over an optical absorption layer. Provided between the first upper cladding layer and the second upper cladding layer is a barrier layer which is provided for the purpose of preventing a diffusion of foreign atoms from the second upper cladding layer or thereabove into the first upper cladding layer and the optical absorption layer. A monolithically integrated laser diode modulator with a strongly coupled super-lattice is disclosed in [11]. In this laser diode modulator, the same epitaxial layer, specifically a strongly coupled, combined super-lattice, is used as active layer of the laser diode and as absorbing layer of the modulator. [12] discloses an integrated modulator semiconductor laser device which is produced on a semiconductor wafer by means of selective crystal growth. For this purpose, each chip region on the semiconductor wafer is divided into two semiconductor regions. There is produced on each first semiconductor region a semiconductor laser which can emit laser light, and there is produced on each second semiconductor region a light modulator which can modulate the intensity of the laser light emitted by the semiconductor laser. A semiconductor device with cascade-modulation-doped quantum well heterostructures is disclosed in [13]. In this semiconductor device, known modulation-doped quantum well heterostructures are cascaded in order to increase the rate of functioning without significantly increasing the operating potentials. Moreover, [14] discloses a semiconductor device with polarization-independent stacked heterostructure, which is similar in its design to the semiconductor device known from [13]. BRIEF SUMMARY OF THE INVENTION The invention is therefore based on the problem of specifying an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator, in the case of which modulator/device the modulator can be used in a wide spectral and temperature range and has fast switching times. The problem is solved by means of an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator with the aid of the features in accordance with the independent patent claims. An electroabsorption modulator comprises a layer sequence of at least five layers, the layer sequence having sequentially a first layer with excess charge carriers of a first charge carrier type, a second layer without excess charge carriers, a third layer with excess charge carriers of a second charge carrier type, a fourth layer without excess charge carriers, and a fifth layer with excess charge carriers of the first charge carrier type. Arranged between the first layer and the third layer is at least one light absorption layer which can generate charge carriers upon irradiation of light of a specific wavelength. Arranged between the third layer and the fifth layer is at least one storage layer which is set up to store charge carriers. A modulator laser device comprises a semiconductor laser and an electroabsorption modulator. The electroabsorption modulator comprises, for example, a layer sequence of at least five layers, the layer sequence having sequentially a first layer with excess charge carriers of a first charge carrier type, a second layer without excess charge carriers, a third layer with excess charge carriers of a second charge carrier type, a fourth layer without excess charge carriers, and a fifth layer with excess charge carriers of the first charge carrier type. Arranged between the first layer and the third layer is at least one light absorption layer, which can generate charge carriers upon irradiation of light of a specific wavelength. Arranged between the third layer and the fifth layer is at least one storage layer which is set up to store charge carriers. The electroabsorption modulator and the semiconductor laser are arranged in such a way that the electroabsorption modulator can transmit or absorb light emitted by the semiconductor laser. In the case of a method for producing an electroabsorption modulator, a layer sequence of at least five sequential layers is produced on a substrate. Excess charge carriers of a first charge carrier type are introduced into the first layer and into the fifth layer of the layer sequence. Excess charge carriers of a second charge carrier type are introduced into the third layer of the layer sequence. By contrast, no excess charge carriers are introduced into the second layer and into the fourth layer of the layer sequence. Both the first layer and the fifth layer of the layer sequence are electrically coupled to in each case at least one electric connection in order to form an electroabsorption modulator. One advantage of the invention can be seen in that the electro a bsorption modulator is clearly a B ipolar Q uantum R eservoir E lectroabsorption M odulator (BIPQREAM) with an npn or a pnp arrangement. Both electrons and holes (therefore the designation “bipolar”) are filled into the absorbing region of the electroabsorption modulator. This leads to a large modulation range between maximum absorption in the swept-out state, that is to say without charge carrier filling in the absorber region, and virtually vanishing absorption in the filled state, that is to say with charge carrier filling in the absorber region. In this case, the modulation range is largely insensitive to spectral and/or temperature fluctuations. The state of maximum absorption is denoted below as “off” state, and the state of minimum absorption as transparency state or “on” state. A further advantage of the invention is the fact that a quantum reservoir is used for storing the charge carriers. This ensures that the maximum modulation shift is reached quickly, since the charge carriers need not be generated each time by absorption of the laser light. In addition, the finite lifetime in the reservoir quantum films ensures a limitation of the quantity of moving charge carriers, and thus of the effective capacitance. It always blocks one of the two pn junctions, for which reason no external current is generated. The charge carrier quantity is automatically controlled during the transparency states, since the charge carrier density in the absorption regions is held just below the respective transparency density dependent on the laser wavelength, because of the type and number of quantum films. The remaining absorption is just so large that it is possible to compensate unavoidable charge carrier losses, chiefly non-radiating and spontaneous recombination in the absorber quantum films. When a switchover is made into the absorption state, the charge carriers are transferred onto the reservoir region. In the case of long absorption times, a permanent filling of the reservoir quantum films is performed from the photocurrent of the modulator quantum wells, which is fed either by a non-vanishing laser signal or—in the special case of pure Q-switching—by the remaining spontaneous emission of the laser. The number of stored charge carriers is limited because of recombination in the reservoir quantum wells. In order to avoid a modulation efficiency dependent on the bit sequence, the type and number of reservoir quantum films should be selected in such a way that the maximum charge carrier quantity is somewhat greater than the quantity required at least for the modulation, and that the latter can be kept even in the case of long “off” states. Possible excess charge carriers are automatically released again to the rising laser field when a switchover is made to “transparent”. The limitation of the charge carrier quantity in this case limits the maximum effective capacitance. The charge reversal of the quantum wells is performed by means of charge carrier drift and by means of diffusion during filling in the respectively forwardly polarized pn junction. The maximum rate is substantially determined by the combined diffusion and capture time and by the charge carrier emission time. The absorption shift can be adapted within a single npn structure by means of the number of quantum wells. Since the absorption in the case of each switching operation changes between maximum (swept-out absorber quantum wells) and vanishing (filled absorber quantum wells), the absorption shift is not in principle a function of the bit sequence. The only variable dependent on the bit sequence is, as described above, the additional space charge capacitance, on the basis of the charge carrier excess after long absorption states. However, it is bounded above by the lifetime of the charge carriers in the reservoir quantum wells. In the electroabsorption modulator according to the invention, use is made for the first time of a bipolar charge carrier filling in order to achieve the largest possible absorption shift in conjunction with the smallest possible spectral sensitivity. In this case, there is neither a need for a biasing current, nor does a rate-limiting recombination occur. The charge carrier quantity required for switching is provided by an appropriate quantum reservoir, which makes scarcely any contribution to the absorption, and is simultaneously bounded above. This permits a very far reaching digital modulation, in which the two optical states are strongly dependent neither on the signal sequence nor on the level of the input signal. The first layer, the third layer and the fifth layer of the layer sequence of the electroabsorption modulator according to the invention are preferably appropriately doped to generate the respective excess charge carriers. Alternatively, the excess charge carriers can also be generated in the respective layers by means of applying appropriate voltages or electromagnetic fields. In a preferred development of the electroabsorption modulator according to the invention, the light absorption layer and the storage layer each have at least one at least one-dimensional quantum system. For example, a layer with embedded quantum points, a layer with at least one quantum wire or a layer made of at least one quantum film can be used as quantum system. The first layer, the third layer or the fifth layer of the electroabsorption modulator according to the invention, or an arbitrary combination of these layers preferably has/have at least one laterally extended insulating layer with a central opening. On the one hand, this limits the current flow through the layer sequence of the electroabsorption modulator and thus the active modulator region in which the laser light to be modulated overlaps with the modulator region. For this purpose, the first layer and the fifth layer of the layer sequence of the electroabsorption modulator are preferably electrically coupled in each case to an electrode. On the other hand, the insulating layer reduces the overall capacitance of the electroabsorption modulator, since the reactive current fraction in the electroabsorption modulator is lower. In this case, the insulating layer is preferably sheathed by the third layer of the electroabsorption modulator. For example, the insulating layer can then be an oxidized region of the third layer. In a preferred development of the modulator laser device according to the invention, the semiconductor laser and the electroabsorption modulator have at least one common electrically conductive connecting layer. In this case, this can be set up in such a way that a common current flow is avoided both through the electroabsorption modulator and through the semiconductor laser. It is thereby possible to achieve a satisfactory decoupling of the electroabsorption modulator from the semiconductor laser. The electroabsorption modulator and the semiconductor laser are preferably monolithically integrated on a semiconductor substrate in the modulator laser device according to the invention. The modulator laser device is therefore a cost-effective component for the datacom sector up to 40 Gbits, which requires no expensive cooling device. For example, the semiconductor laser can be a vertically emitting laser, the electroabsorption modulator and the semiconductor laser then being arranged vertically above one another in the modulator laser device. Alternatively, an edge-emitting laser can be used as semiconductor laser, the electroabsorption modulator and the semiconductor laser being arranged laterally next to one another. If an edge-emitting laser is used as a semiconductor laser, the latter preferably has a resonator based on Bragg structures. The invention therefore constitutes a temperature-noncritical optical electroabsorption modulator which also operates digitally in a specific embodiment. Exemplary embodiments of the invention are illustrated in the figures and will be explained in more detail below. In this case, like reference symbols designate like components. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a first exemplary embodiment of the invention; FIG. 2 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a second exemplary embodiment of the invention; FIG. 3 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a third exemplary embodiment of the invention; FIG. 4 shows an equivalent electric circuit diagram for an electroabsorption modulator in accordance with the second exemplary embodiment; FIG. 5 shows a cross section through a modulator laser device in accordance with a first exemplary embodiment of the invention; FIG. 6 shows a cross section through a modulator laser device in accordance with a second exemplary embodiment of the invention; FIG. 7 shows a top view of a modulator laser device in accordance with a third exemplary embodiment of the invention; and FIG. 8 shows a top view of a modulator laser device in accordance with a fourth exemplary embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a schematic diagram 100 of the energy bands of an electroabsorption modulator in accordance with a first exemplary embodiment of the invention. The diagram 100 of the energy bands illustrates the active modulator region of the electroabsorption modulator in the absorbing (“off”) state. The electroabsorption modulator comprises a layer sequence of a first n-doped outer lead layer 101 , a first undoped, intrinsic intermediate layer which forms the reservoir region 104 , a p-doped middle layer 102 , a second undoped, intrinsic intermediate layer, which forms the absorber region 106 , and a second n-doped outer lead layer 103 . The first n-doped outer lead layer 101 forms a first pn junction together with the middle layer 102 , and the second n-doped outer lead layer 103 forms a second pn junction with the middle layer 102 . The first pn junction is forward-biased, while the second pn junction is reverse-biased. The forward-biased first pn junction therefore constitutes the reservoir region 104 , while the reverse-biased second pn junction constitutes the absorber region 106 . A reservoir quantum film 105 is arranged in the reservoir region 104 , and an absorber quantum film 107 is arranged in the absorber region 106 . Use is made for the middle layer 102 of a material which has a higher band gap than the material for the first or second n-doped outer lead layer 101 , 103 , respectively. Electron leakage currents from the forward-biased first pn junction into the reverse-biased second pn junction are thereby reduced. This clearly means that the middle layer 102 substantially reduces an electron flow from the reservoir region 105 into the absorber region 107 . As long as the electroabsorption modulator is in the absorbing state, incident laser light 108 is converted in the absorber quantum film 107 of the absorber region 106 into charge carrier pairs. The positively charged holes (defect electrons) migrate owing to charge carrier drift into the middle layer 102 and finally fill the reservoir quantum film 105 in the reservoir region 104 by means of diffusion. The quantity of electrons which corresponds to the holes flows off via the second n-doped outer lead layer 103 , and induces a photocurrent between the second n-doped outer lead layer 103 and the first n-doped outer lead layer 101 , when the first n-doped outer lead layer 101 and the second n-doped outer lead layer 103 are coupled to one another by means of an outer electric circuit. The fundamental absorption edge of the absorber quantum film 107 is set in such a way that the incident laser light 108 is efficiently absorbed at all operating temperatures. The band gap of the reservoir quantum film 105 is selected either to be greater or to be smaller than the band gap of the absorber quantum film 107 . If the band gap of the reservoir quantum film 105 is greater than the band gap of the absorber quantum film 107 , a short circuit of the electroabsorption modulator (U(t)=0) leads automatically to the transparent state (“on” state) of the electroabsorption modulator, since all generated charge carriers predominantly remain in the absorber quantum film 107 . If the band gap of the reservoir quantum film 105 is smaller than the band gap of the absorber quantum film 107 , a short circuit of the electroabsorption modulator (U(t)=0) leads to the absorption state (“off” state) of the electroabsorption modulator owing to the separation of the generated charge carriers, as a result of which a non-vanishing outer short circuit photocurrent flows. In this case, the optical filling factor of the reservoir quantum film 105 can be selected to be smaller than for the absorber quantum film 107 , in order to reduce the absorption of the incident laser light 108 in the reservoir quantum film 105 . If the filling factors, that is to say the probabilities for the absorption of a photon of the incident laser light 108 , are similar for the reservoir region 104 and the absorber region 106 , it is also possible to carry out a frequency doubling by means of the electroabsorption modulator, since then both quantum films 105 , 107 operate alternately as reservoir and as absorber. The electroabsorption modulator illustrated by means of the diagram 100 is an npn structure in which electrons are used to switch the absorber region 106 . If, instead of this, recourse is made to a pnp structure, holes are used to switch the absorber region 106 . A schematic diagram 200 of the energy bands of an electroabsorption modulator in accordance with a second exemplary embodiment of the invention is illustrated in FIG. 2 . By contrast with FIG. 1 , apart from the p-doped middle layer 102 , the two n-doped outer lead layers 101 , 103 also have a material with a higher band gap, in order to reduce the hole leakage currents. This is particularly sensible whenever very flat quantum films with a low valence band offset are used as reservoir quantum film 105 and as absorber quantum film 107 . All layer junctions, also termed heterobarriers, are implemented by means of suitably doped variation layers 201 , 202 , 203 and 204 , such that the respective majority charge carriers perceive a negligibly small electric resistance. The variation layers 201 , 202 , 203 , 204 comprise a continuous variation in the doping profile. Furthermore, the variation layers 201 , 202 , 203 , 204 in accordance with this exemplary embodiment of the invention comprise a layer thickness of 9 nm in each case. Furthermore, the diagram 200 shows the use of a selectively oxidizable layer 205 within the middle layer 102 . In the preferred material system Al x In y Ga 1−x−y As 1−m−n Sb m N n for growing on GaAs substrates, such a selectively oxidizable layer 205 usually comprises a very high aluminum content of x>0.8. Alternatively, it is also possible to grow a layer sequence of thin super-lattice layers, of which at least one individual layer should then have a correspondingly high aluminum content. During the production of the selectively oxidizable layer 205 , the selective oxidation is stopped in good time in order no longer to oxidize the active modulator region, which has a substantial overlap with the laser light. A reduction in the effective modulator capacitance is achieved by means of the selectively oxidizable layer 205 , as is illustrated in FIG. 4 . FIG. 3 shows a schematic diagram 300 of the energy bands of an electroabsorption modulator in accordance with a third exemplary embodiment of the invention. The difference between the electroabsorption modulator in accordance with the third exemplary embodiment and the electroabsorption modulator in accordance with the second exemplary embodiment is explained with the aid of the difference between the schematic diagrams 200 and 300 . A selectively oxidizable layer 205 within the middle layer 102 is illustrated in FIG. 2 , while FIG. 3 shows the energy bands of an electroabsorption modulator of the two selectively oxidizable layers 301 , 302 . In each case, one of the two selectively oxidizable layers 301 , 302 is arranged at the edge of each of the two n-doped outer lead layers 101 , 103 . A reduction in the effective modulator capacitance is also achieved by means of the two selectively oxidizable layers 301 , 302 . Because of the reduction in the effective modulator capacitance, it is possible to achieve a simplified electrical operation of the electroabsorption modulator, and thus a faster intrinsic modulation of the electroabsorption modulator. It is possible to achieve an increase in the fraction of the electron filling compared with the hole filling by reducing the spacing of the absorber quantum film 107 from the fourth variation layer 204 . This corresponds to a reduced charge carrier transparency density. By contrast with pure BRAQWETs, however, charge carriers of the respective other polarity (here, therefore holes) from the reservoir quantum film 105 are still used for a complete transparency of the electroabsorption modulator. In the borderline case of an n-doped absorber region 106 , only low charge carrier densities are required, but the level of the absorption of the electroabsorption modulator is then directly dependent on the level of the input voltage U(t), and this leads to an analogue (non-digital) modulation response of the electroabsorption modulator. FIG. 4 shows an equivalent electric circuit diagram 400 for an electroabsorption modulator in accordance with the second exemplary embodiment. An input voltage U(t) is present at the electroabsorption modulator. This is compounded from a bias voltage U bias present at the electroabsorption modulator and an effective modulator voltage U mod , which is generated by the generated charge carriers. Both the capacitance effect of the active modulator region and the capacitance effect of the passive modulator region are taken into account for the overall capacitance of the electroabsorption modulator. The ohmic lead resistance of the active modulator region firstly represents an equivalent resistor R sa . The charge carrier generation in the absorber region 106 causes a photocurrent I ph between the external connections of the electroabsorption modulator, which overcomes an ohmic resistance R p during the charge carrier preparation between absorber region 106 and reservoir region 104 . The reservoir region 104 and the absorber region 106 are symbolized respectively by means of a capacitor C 1a , C 2a . An equivalent resistor R sp represents the ohmic lead resistance of the passive modulator region. The laterally selectively oxidizable layer 205 enclosed by the middle layer 102 is symbolized by means of the capacitors C 1p , C ox and C 2p . The capacitance effect of the active and passive modulator regions C mod,act and C mod,pass , respectively, can now be calculated from the following equations, taking account of the generated charge carrier quantity ΔQ: C mod , act = ( 1 C 1 ⁢ a + 1 C 2 ⁢ a ) - 1 + Δ ⁢   ⁢ Q U mod , ( 1 ) C mod , pass = ( 1 C ox + 1 C 1 ⁢ p + 1 C 2 ⁢ p ) - 1 . ( 2 ) The following condition should be satisfied in order to be able to ensure reliable operation of the electroabsorption modulator: C mod,pass R sp <C mod, act ( R sa +R p ).  (3) The overall capacitance of the electroabsorption modulator C mod is therefore yielded by adding the capacitance effects of the active and the passive modulator regions, which is therefore smaller than the overall capacitance C mod c of a modulator without a selectively oxidized layer 205 : C mod =C mod,act +C mod,pass <C mod c .  (4) The maximum achievable 3 dB cut off frequency f 3dB,int for the current modulation of the electroabsorption modulator is therefore yielded in accordance with f 3 ⁢ dB , int = 1 2 ⁢ π ⁡ ( R sa + R p ) ⁢ C mod , act = f 3 ⁢ dB , int 0 , ( 5 ) and is identical to the maximum achievable 3 dB cut off frequency f 3dB,int 0 without a selectively oxidizable layer 205 . FIG. 5 illustrates a cross section through a modulator laser device 500 in accordance with a first exemplary embodiment of the invention. The modulator laser device 500 is composed of an electroabsorption modulator 200 in accordance with the second exemplary embodiment, and of a surface-emitting semiconductor laser with vertical resonator (VCSEL). In this case, the electroabsorption modulator 200 is monolithically integrated within the rear reflector of the semiconductor laser. In accordance with the present embodiment of the invention, Al x Ga 1−x As is used as basic material for the semiconductor laser and for the electroabsorption modulator 200 . This material can have additional constituents such as, for example, indium or nitrogen for producing the individual layers, and/or be n-doped or p-doped in accordance with the requirements. The modulator laser device 500 firstly has an n-doped substrate 501 with a rear n-contact 502 . A plurality of n-doped resonator Bragg reflectors 503 are applied to the n-doped substrate 501 . The n-doped substrate 501 , the n-contact 502 and the n-doped resonator Bragg reflector 503 together form the first n-doped outer lead layer 101 . The following adjoin the main components of the electroabsorption modulator 200 : the reservoir region 104 with at least one reservoir quantum film 105 , followed by the p-doped middle layer 102 with a selectively oxidized layer 205 for reducing the overall capacitance and the absorber region 106 with at least one absorber quantum film 107 . The absorber quantum film 107 and the reservoir quantum film 105 typically each have a thickness of 7 nm. The absorber region 106 and the reservoir region 104 in each case have a layer thickness of the order of magnitude of 120 nm to 150 nm. The layer thickness of the middle layer 102 is of the order of magnitude of 90 nm. Situated above the absorber region 106 is the second n-doped outer lead layer 103 , which forms the common ground contact of the semiconductor laser and of the electroabsorption modulator, and is provided with suitable n-contacts 504 . In order to reduce electrical crosstalk between the semiconductor laser and the electroabsorption modulator, the layer conductivity of the second n-doped outer lead layer 103 should be sufficiently high. This can be ensured by means of a suitable doping and an adequate thickness. An additional reflector layer 505 between the active zone of the semiconductor laser and the electroabsorption modulator is provided for setting the desired absorption or photon round trip time. This additional reflector layer 505 influences the optical overlap of the laser modes with the absorber quantum film 107 . Adjoining the additional reflector layer 505 is the active laser zone 506 of the semiconductor laser with a laser quantum film 507 and a plurality of p-doped resonator Bragg reflectors 508 with a current aperture 509 , and the laser contacts 510 . The laser contacts 510 are arranged in such a way that the laser light 511 emitted by the semiconductor laser and which is influenced by the integrated electroabsorption modulator 200 can leave the modulator laser device 500 perpendicular to the surface. The semiconductor laser emits laser light at a wavelength of 850 nm. The Bragg resonator of the semiconductor laser has an effective length of 1.8 μm, and the current aperture 509 has a diameter of 6 μm. The current density is of the order of magnitude of 5 kA/cm 2 . The present electroabsorption modulator 200 operates in the range of the loss modulation, which is limited in principle only by the mean photon lifetime in the resonator. This is τ p =2.94 ps in the system presented. The emitted wavelength of the semiconductor laser is a function both of the Bragg resonator and of the active laser zone 506 . It is possible, for example, to set and modulate efficiently all the wavelengths in the range from approximately 700 nm to approximately 1500 nm by means of a suitable mixing ratio of Al x In y Ga 1−x−y As 1−m−n Sb m N n for the active laser zone 506 of the semiconductor laser, and of a similar mixing ratio for the absorber quantum film 107 of the electroabsorption modulator. The modulator laser device 500 can be produced by means of conventional process methods. The current aperture 509 of the semiconductor laser can be produced both by means of ion implantation and also by means of lateral oxidation or an appropriate combination of lateral oxidation with ion implantation. FIG. 6 shows a cross section through a modulator laser device 600 in accordance with a second exemplary embodiment of the invention. The modulator laser device 600 in accordance with the second exemplary embodiment differs from the modulator laser device 500 in accordance with the first exemplary embodiment essentially in that instead of being arranged, as shown in FIG. 5 , below the semiconductor laser the electroabsorption modulator 200 is now arranged above it. Situated over the entire surface on the rear of the substrate is the p-contact 601 , followed by p-doped resonator Bragg reflectors 508 with current aperture 509 and the active laser zone 506 with laser quantum film 507 . Arranged there above are the second n-doped outer lead layer 103 , which is laterally extended and serves as common ground layer for the electroabsorption modulator 200 and the semiconductor laser, with the n-contacts 504 , and a coupling reflector 602 for optically coupling the electroabsorption modulator 200 to the semiconductor laser. These are covered by the modulator region comprised of absorber region 106 with absorber quantum film 107 , middle layer 102 with selectively oxidizable layer 205 and reservoir region 104 with reservoir quantum film 105 . The “hot” modulator electrode is formed by the n-doped resonator Bragg reflectors 503 and the metal contact 603 , which together implement the first n-doped outer lead layer 101 . By comparison with the modulator laser device 500 in accordance with the first exemplary embodiment, the modulator laser device 600 in accordance with the second exemplary embodiment has, inter alia, the advantage of a smaller modulator area, as a result of which the capacitances of the electroabsorption modulator are reduced. However, the production of the semiconductor laser, in particular the current aperture 509 , is more complicated because of the required uniformity of the semiconductor laser. The current aperture 509 can, in turn, be produced both by means of oxidation, by means of ion implantation, by means of multiple epitaxy with buried tunnel contact, or by means of a combination of these production methods. A particular feature of the modulator laser device 600 in accordance with the second exemplary embodiment is that it is also suitable in strip geometry for edge-emitting semiconductor lasers with monolithically integrated electroabsorption modulator. In this case, suitable wave guiding layers then replace the resonator Bragg reflector 503 , 508 and the additional reflector layer 505 . Depending on the composition of the wave guiding layers, it is possible to select either a coupled waveguide structure or a common waveguide structure for absorber and laser. FIG. 7 shows a top view of a modulator laser device 700 in accordance with a third exemplary embodiment of the invention. The modulator laser device 700 combines an edge-emitting semiconductor laser with a monolithically integrated electroabsorption modulator. A coupled waveguide structure for the semiconductor laser and the electroabsorption modulator is preferred in this case. The waveguidance of the semiconductor laser is essentially performed via the additional reflector layer 505 , which can be influenced technologically by the type of the resonator grating 701 . The emission of the laser light generated by the semiconductor laser and influenced by means of the electroabsorption modulator takes place by means of the emission opening 702 on the coupled waveguide structure. Given a suitable selection of the waveguide coupling, the position of the resonator grating 701 and its length L G , the overall length L of the modulator laser device 700 and of the modulator length L M , it is also possible to implement semiconductor lasers with a DBR-type or DFB-type laser structure. The decoupling between the electroabsorption modulator and the semiconductor laser can then be optimized by means of the resonator grating for the waves returning from the electroabsorption modulator. A selective oxidation in the lower p-doped resonator Bragg reflector 508 is preferably used to define a current aperture and simultaneous lateral waveguidance for the semiconductor laser. A top view of a modulator laser device 800 in accordance with a fourth exemplary embodiment of the invention is illustrated in FIG. 8 . By contrast with the modulator laser device 700 in accordance with the third exemplary embodiment, in the modulator laser device 800 in accordance with the fourth exemplary embodiment the electroabsorption modulator 200 comprises two sections which are electrically decoupled from one another, but strongly coupled optically to one another. In this case, a common waveguide is used for the semiconductor laser and the electroabsorption modulator 200 , and its optical disturbance on the section L C in the region of the electric decoupling should be as small as possible. The electric decoupling can be performed, for example, by means of deep etching. The optical coupling can be optimized, for example, by means of antireflection coating or by means of filling in material with a sufficiently high refractive index at the disturbed site. The optical overlap of the absorber region 106 can be reduced by means of an asymmetric waveguide design. However, the modulator length L M should then be correspondingly enlarged. Furthermore, the waveguidance within the modulator should be rendered sufficiently strong so that the intensity in the middle layer 102 and in the reservoir region 104 already drops strongly, and thus the disturbance becomes negligibly small over the short section L C . An optional second modulator contact 801 can be provided, for example, with a defined potential in order to switch the passive region, lying there below, of the electroabsorption modulator 200 to be transparent in a defined fashion so that the outcoupling efficiency of the semiconductor laser is not reduced by parasitic absorption. The following publications are quoted in this document: [1] P. Steinmann, B. Borchert, B. Stegmutller: “Improved Behaviour of Monolithically Integrated Laser/Modulator by Modified Identical Active Layer Structure”, IEEE Photonics Technol. Lett., Vol. 9, No. 12, pp. 1561-1563, 1997 [2] S. F. Lim, J. A. Hudgings, L. P. Chen, G. S. Li, W. Yuen, K. Y. Lau, C. J. Chang-Hasnain; “Modulation of a Vertical-Cavity Surface-Emitting Laser using an Intracavity Quantum-Well Absorber”, IEEE Photonics Technol. Lett., Vol. 10, No. 3, pp. 319-321, 1998 [3] J. A. Hudgings, R. J. Stone, C. H. Chang: “Dynamic Behavior and Applications of a Three-Contact Vertical Cavity Surface-Emitting Laser”, IEEE J. of sel. Topics in Quantum Electronics, Vol. 5, No. 3, pp. 512-519, 1999 [4] P. J. Bradley, C. Rigo, A. Stano: “Carrier Induced Transient Electric Fields in a p-i-n InP-InGaAs Multiple-Quantum-Well Modulator”, IEEE J. of Quantum Electronics, Vol. 32, No. 1, pp. 43-52, 1996 [5] K. W. Jelley, R. W. H. Engelmann, K. Alavi, H. Lee: “Well Size Related Limitations on Maximum Electroabsorption in GaAs/AlGaAs Multiple Quantum Well Structures”, Appl. Phys. Lett., Vol. 55, No. 1, pp. 70-72, 1989 [6] M. Preisel, J. Mork: “Phonon-Mediated Carrier Capture in Quantum Well Lasers”, J. Appl. Phys., Vol. 76, No. 3, pp. 1691-1696, 1994 [7] M. Wegener, J. E. Zucker, T. Y. Chang, N. J. Sauer, K. L. Jones, D. S. Chemla: “Absorption and Refraction Spectroscopy of a Tunable-Electron-Density Quantum-Well and Reservoir Structure”, Phys. Rev. B., Vol. 41, No. 5, pp. 3097-3104, 1990 [8] J. Wang, J. P. Leburton, J. L. Educato, J. E. Zucker: “Speed Response Analysis of an Electron-Transfer Multiple-Quantum-Well Waveguide Modulator”, J. Appl. Phys., Vol. 73, No. 9, pp. 4669-4679, 1993 [9] N. Agrawal, M. Wegener: “Ultrafast Graded-Gap Electron Transfer Optical Modulator Structure”, Appl. Phys. Lett., Vol. 65, No. 6, pp. 685-687, 1994 [10] EP 1 069 456 A2 [11] DE 692 03 998 T2 [12] DE 44 29 772 C2 [13] DE 690 15 228 T2 [14] EP 0 599 826 B1

Electroabsorption modulator ( 100 ) having a layer sequence of at least five sequential layers, having at least one light absorption layer ( 106 ) which is arranged between the first layer ( 101 ) and the third layer ( 102 ) and is set up to generate charge carriers upon irradiation of light ( 108 ) of a specific wavelength, and having at least one storage layer ( 104 ) which is arranged between the third layer ( 102 ) and the fifth layer ( 103 ) and is set up to store charge carriers.

FIELD OF THE INVENTION This invention relates generally to the secure delivery and receipt of data using public key cryptography (PKC); more particularly, to the secure delivery and receipt of encrypted messages and Secure Multipurpose Internet Mail Extension (S/MIME) encrypted messages where the sender does not possess the credentials of the recipient either because the recipient is not enrolled in a Public Key Infrastructure (PKI) or the recipient has not provided their public key to the sender. BACKGROUND OF THE INVENTION Several discoveries have been made to address the need for securing messages between a sender and receiver. One such discovery being the Diffie-Hellman algorithm and the Rivest Shamir Adleman public key crypto system discovered in the mid 1970s. The significance of these discoveries is that they have become standards on which present encryption systems are built. The Diffie-Hellman algorithm is especially suited to secure real time communications. The Diffie-Hellman algorithm requires the participation of both the sender and receiver. To execute, the two participants choose two numbers which in turn are used in conjunction with secret numbers which are correspondingly secret to each of the two participants to derive a third number which is exchanged between the two participants. The exchanged numbers are then used in a process to encrypt the messages between the two participants and then to decrypt the messages. This method therefore requires the active participation of the recipient in order to send a secure message. As a consequence, the system is best suited for only two participants in the message, and is not suited for multiple participants. Furthermore, although the system secures the confidentiality of the message satisfactorily it does not ensure the authenticity of the message or the sender in terms of what is known as a “digital signature”. As such, the Diffie-Hellman algorithm is predominantly used to secure the real time communication sessions between a sender and a receiver over a network. The Rivest Shamir Adleman (RSA) public key crypto system, while inspired by the Diffie-Helman algorithm, developed a method that 1.) does not require the active participation of the recipient, 2.) allows for more than two participants in a message, and 3.) established a framework to provide authenticity of both the sender and of the message itself in addition to securing the message between the sender and the recipient(s). Securing messages between senders and recipients can be accomplished in an infinite number of ways. To secure email, arguably the most widely deployed application on the Internet, the S/MIME standard was developed in the late 1990s. While there are proprietary methods for securing email messages such as those developed by organizations such as PGP, Hushmail, Zixit, Ziplip etc., S/MIME has become the dominant world standard to secure email communications. The S/MIME protocol was established by RSA Data Security and other software vendors in 1995. The goal of S/MIME was to provide message integrity, authentication, non-repudiation and privacy of email messages through the use of Public Key Infrastructure (“PKI”) encryption and digital signature technologies. Email applications that support S/MIME assure that third parties, such as network administrators and ISPs, cannot intercept, read or alter messages. S/MIME functions primarily by building security on top of the common MIME (Multipurpose Internet Mail Extension) protocol, which defines the manner in which an electronic message is organized, as well as the manner in which the electronic message is supported by most email applications. Currently, the most popular version of S/MIME is V3 (version three), which was introduced in July, 1999. Further information on S/MIME standardization and related documents can be found on the Internet Mail Consortium web site and the IETF S/MIME working group “web site.” The S/MIME V3 Standard consists generally of the following protocols: Cryptographic Message Syntax (RFC 2630); S/MIME Version 3 Message Specification (RFC 2633); and S/MIME Version 3 Certificate Handling (RFC 2632). S/MIME and similar secure message systems rely on PKC to invoke security. With S/MIME security, a MIME message is secured by digitally signing the message which is conducted by encrypting a message digest hash with the private key of the sender. This is what is known as a digital signature. Optionally, the message content with the digital signature is encrypted using the public key of the recipient. The encrypted message and digital signature comprise the S/MIME email message that is then sent to the recipient. Upon receiving the message, the recipient's private key is used to decrypt the message. The recipient re-computes the message digest hash from the decrypted message and uses the public key of the sender to decrypt the original message digest hash (the digital signature) and compares the two hashes. If the two hashes are the same, the recipient has validation of the authenticity of the sender and of the integrity of the message. Consequently, S/MIME and similar secure message systems generally require that both the sender and the recipient(s) be enrolled in a PKC system and that the public keys of each be accessible in order for the message to be secured and for the sender and message to be authenticated. As such, if the recipient is not enrolled in a PKI, or the sender does not have access to the recipient's(s') key(s), the sender will not be able to send a secure message to the recipient(s). What is needed therefore is a system, computer program and method for delivering encrypted messages to recipient(s) where the sender does not possess the credentials of the recipient(s) or some subset thereof. What is further needed is the aforesaid system, computer program and method that can access or generate message encryption keys, which can be used by the sender to ensure the privacy of the message for the recipient. What is still further needed is the aforesaid system, computer program and method that is easily deployed in either a browser or on a client application provided at the network-connected devices themselves. What is also needed is a web-based or client based system, computer program and method whereby the encryption persists throughout the communication and storage of data. What is also needed is a web-based or client-based system, computer program and method whereby the message decryption key is stored securely and accessed securely by the recipient in order to decrypt the message. SUMMARY OF THE INVENTION The system, method and computer program of the present invention enables users to create and send encrypted email or other encrypted messages either through a browser or through client software without the need to have the certificate(s) or public key(s) of the recipient(s). From a sender usability perspective this eliminates the sender's inability to send secure messages when a recipient is not enrolled in a PKI and therefore does not possess a PKI certificate or when the recipient's certificate is not in the possession of the sender. In another aspect of the present invention permits recipients to access private PKC based encrypted messages without the need to be enrolled in a PKI. In another aspect of the present invention permits recipients to access PKC keys over the Internet from any network-connected device. This eliminates the need for location specific private key and digital certificate storage. BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the preferred embodiment(s) is(are) provided herein below by way of example only and with reference to the following drawings, in which: FIG. 1 a is a schematic System Architectural Component Diagram of the secure message system of the present invention. FIG. 1 b is a program resource chart illustrating the resources of the application of the present invention, in one embodiment thereof. FIG. 1 c is a program resource chart illustrating the resources of the application of the present invention, in another embedment thereof. FIG. 2 a is a flow chart that depicts the steps in creating, signing, and encrypting a secure message and the generation of security keys for non-enrolled recipients using browser based messaging, in accordance with one aspect of the method of the present invention. FIG. 2 b is a flow chart that depicts the steps in creating, signing, and encrypting a message and the generation of security keys for non-enrolled recipients using client based messaging, in accordance with another aspect of the method of the present invention. FIG. 3 a is a flow chart that depicts the steps for receiving, verifying and decrypting an encrypted message by user who is not enrolled in a PKI using a browser. FIG. 3 b is a flow chart that depicts the steps for receiving, verifying and decrypting an encrypted message by users who are not enrolled in a PKI using a client. FIG. 4 depicts a possible user interface for creating a shared secret to secure a message. FIG. 5 depicts a possible user interface for responding to a challenge question to provide a shared secret FIG. 6 is a flow chart that depicts the steps in signing and encrypting messages in connection with the various components of a PKI infrastructure. FIG. 7 a is a flow chart that depicts the steps in creating, signing, and encrypting a message for non-enrolled recipients using client based messaging and a trusted intermediary. FIG. 7 b is a flow chart that depicts the steps for retrieving and verifying an encrypted message by user who is not enrolled in a PKI using a browser or client and a trusted intermediary. In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in FIG. 1 , at least one known network-connected device 10 is provided. Network-connected devices 10 may consist of a number of digital devices that provide connectivity to a network of computers. For example, the network-connected device 10 may consist of a known personal computer or a known WAP device, cell phone, PDA or the like. The network-connected device 10 is connected to the Internet 12 in a manner that is known. Specifically in relation to FIG. 1 , the connection of a network-connected device 10 that is a known WAP device to the Internet is illustrated, whereby a known WAP to WEB gateway 107 is provided, in a manner that is also known. Also as shown in FIG. 1 a , each of the network-connected devices 10 may include a known computerized device, which includes a browser 20 and/or client application 40 . The browser can be a standard Internet based browser, such as Netscape's NAVIGATOR.™. or Microsoft's INTERNET EXPLORER.™. or a known mini browser for wireless devices such as cell phones or PDM. Client application 40 can be a known email program such as Microsoft's OUTLOOK.™., OUTLOOK EXPRESS.™., LOTUS NOTES.™., Novell's GROUPWISE.TM., EUDORA.™ or another known email program for wireless devices such as cell phones or PDAs, including those commonly bundled in such devices as part of the devices' operating system or is distributed as a separate component. The client application 40 can also be a custom client used to create secure messages. Each of the network-connected devices 10 also includes the application 22 of the present invention, which consists of the computer program of the present invention. Certain attributes of this application 22 , in particular the manner in which it permits Public Key Cryptography (PKC) enabled communications over wired and wireless networks is disclosed in U.S. Pat. No. 6,678,821 issued to Echoworx Corporation and the Co-Pending patent application Ser. Nos. 10/178,224 and 10/379,528 (the “patent” or the “Co-Pending patent applications”, as applicable). As particularized below, the application 22 includes a PKC utility (not shown). In one particular embodiment of the application 22 , illustrated in FIG. 1 b , the application 22 consists of a specialized browser extension 309 or plug-in. Specifically in this particular embodiment of the invention, the application 22 and the browser 20 inter-operate by means of, for example, customized HTML tags. As opposed to using an intermediate host server, or a relatively large computer program (as is the case with prior art technologies), application 22 preferably provides the necessary resources to enable the network-connected device 10 , as particularized below, to function with any third party PKI system, including for example, ENTRUST™, MICROSOFT™, BALTIMORE™, RSA™ and so forth. It should also be understood that the functions of the application 22 described herein can also be provided as an “ACTIVE X OBJECT” in a manner that is known, or integrated directly into a browser. In another embodiment of application 22 , illustrated in FIG. 1 c , the application 22 consists of a client extension 409 or plug-in is provided in a manner that is known. Specifically, the application 22 and the client application 40 inter-operate by means of, for example, customized programming specific to the client application 40 . As opposed to using an intermediate host server, or a relatively large computer program (as is the case with prior art technologies), application 22 (in this particular embodiment of the invention also) preferably provides the necessary resources on the network-connected device 10 , as particularized below, to function with any third party PKI system, including for example, ENTRUST™, MICROSOFT™, BALTIMORE™, RSA™ and so forth. It should also be understood that the functions of application 22 described herein can also be integrated directly into the client application 40 . Application 22 functions as a cryptographic utility, provided in the manner described in the patent and Co-Pending patent applications, such that the application 22 is adapted to perform at the network-connected device 10 one or more of a series of cryptographic operations, including but not limited to: Digital signature of data in S/MIME format; Encryption of data in S/MIME format; Digital signature of data in form fields; Encryption of data in form fields; Decryption of data in form fields; Verification of signature of data in form fields; Digital signature and encryption of data in form fields; Verification of Digital signature and decryption of data in form fields; Digital signature of full pages; Verification of digital signature of full pages; Encryption of full pages; Decryption of full pages; and File attachment encryption and signing. Specifically, application 22 includes a Crypto Library 300 , provided in a manner that is known. In one particular embodiment of the present invention, the application 22 also includes a User Certificate and Private Key 302 which contains the cryptographic data required to encrypt and/or digitally sign data included in data communications (including email) contemplated by the present invention. For example, in one particular implementation of the present invention, namely one whereby Microsoft software provides the Security Services 312 , the .PFX or DER (Distinguished encoding rules ASN.1) encoded X509 certificate files required to authenticate the sender, or encrypt data for the recipient, are downloaded to the network-connected device 10 or are generated by the network-connected device 10 . The .PFX file is an encrypted file that is used to access the user credentials and private key required to process cryptographic operations. The PFX file is formatted based on the PKCS12 standard. The DER encoded X509 certificate file provides the public key and certificates of the recipient. Security Services 312 should be understood as a general term describing a known PKI infrastructure. PKI infrastructures can vary as to the particulars of their architecture, or their hardware or software components. Typically, however, a PKI infrastructure consists of the components illustrated in FIG. 1 a : a Certificate Authority for issuing and certifying certificates for enrolled users; a Lightweight Directory Access Protocol (or “LDAP”) for storing the public key and certificates of enrolled users; and a Certificate Revocation List (or “CRL”) for revoking certificates. In another aspect of Security Services 12 also illustrated in FIG. 1 a , a Roaming Key Server (or “RKS”) is used for storing private keys of enrolled users. As stated earlier, application 22 of the present invention includes a PKC extension, and specifically a browser extension 309 or the email client extension 409 described below. The PKC extension permits the encryption and decryption of data communications (including email) in a browser or email client, as particularized herein. This has the advantage of broad-based deployment as browser technology and email software is commonplace. This also has the advantage of deployment across wireless and wired networks as the application 22 of the present invention, including the browser or client extension, can be associated with a web browser or a WAP browser, as shown in FIG. 1 a . In addition, the invention disclosed herein requires only a browser or email client and the associated application 22 at each network-connected device 10 rather than a relatively thick client at each network-connected device 10 which reduces the resources required at each such device to provide PKI functionality. Also, as further explained below, in accordance with the present invention, secure encrypted communications are possible without the need to possess the certificates and public key of the recipients, resources usually required to send fully encrypted messages such as S/MIME messages on the network-connected device 10 . Each of the browser extension 309 and the email client extension 409 is generally reduced to code in a manner known by a skilled programmer. However, it is desirable for the browser extension 309 or client extension 409 of the present invention to have a number of attributes. First, as a result of the method of the present invention detailed below, it is desirable that the browser extension 304 and client extension 409 be able to generate a public key pair and to secure the private key based on a secret that is shared between the sender and the recipient such that the password is used to encrypt the private key. Second, the key generation, security, and the encryption and decryption of data described herein involve a potential security risk if the browser extension 309 or client extension 409 is not designed properly. Specifically, it is necessary to ensure that browser memory is (in the case of the browser extension 309 ) utilized in the course of the cryptographic operations such that security is not compromised. In one particular embodiment of the present invention, this is achieved by using the “TEMP” memory space of the browser 20 or client application 40 , in a manner known by a skilled programmer. Third, the browser extension 309 or client extension 409 further includes a CLEANUP ROUTINE or equivalent provided in a manner that is known that eliminates any remnants from the memory associated with the browser, email client, or otherwise with the network-connected device 10 , of either the message, the user credential or private key that is part of the User Certificate and Private Key Store 302 , in order to maintain confidentiality. Specifically, for example in relation to the browser extension 309 , the browser extension 309 is configured such that it will not store a copy of the email in the browser cache. In addition, the browser extension 309 or client extension 409 will delete any copies of any attachments associated with a secure message. As stated earlier, the present invention also contemplates that the browser extension 309 or client extension 409 provides means to establish a shared secret that will be used by the browser extension 309 or the client extension 409 to encrypt the private key corresponding to the public key that is used to encrypt the message or to authenticate a non-enrolled recipient to a trusted intermediary. This particular aspect of the present invention is illustrated in FIGS. 4 and 5 . In addition, the present invention contemplates that the browser extension 309 and the client extension 409 facilitate the notification and delivery of secure messages to a recipient not enrolled in a PKI. More particularly, the browser extension 309 or the client extension 409 is adapted to permit the non-enrolled recipient to respond to a request for a shared secret which upon successful provision thereof releases the private key or authenticate the non-enrolled recipient (illustrated in FIG. 1 a ) to a trusted intermediary in order to decrypt and view the secure message. Also connected to the Internet 12 , is a web server 106 that is provided using known hardware and software utilities so as to enable provisioning of the network-connected device 10 , in a manner that is known. The web server 106 includes a web application 16 . The web application 16 is adapted to execute the operations, including PKI operations, referenced below. The system, computer program and method of the present invention are directed to: 1. Creating, encrypting and delivering secured messages including S/MIME compliant email messages to an email server or a message storage/database server; 2. Retrieving and deciphering secured messages, including S/MIME compliant email messages, from an email server or a message storage/database server; and 3. Creating, securing and delivering recipient data and private key(s) to a secure storage server. In order to achieve the foregoing, the system, computer program and method of the present invention rely on aspects of the patent and the Co-Pending patent applications for engaging in PKI enabled transactions. Specifically, email messages are created and delivered in accordance with the present invention in a manner that is analogous with the “POSTING DATA ON A SECURE BASIS” and “SECURE DELIVERY OF S/MIME ENCRYPTED DATA” described in the Co-Pending patent applications. An email message is retrieved and deciphered in the manner described under the heading “RETRIEVING OF DATA ON A SECURE BASIS” and the “SECURE RECEIPT OF S/MIME ENCRYPTED DATA” also described in the Co-Pending patent Applications. As illustrated in FIG. 1 a , one aspect of the system of the present invention also includes a known email server or message server 306 . The email server or message server 306 sends and receives emails in a manner that is well known. The email server or message server 306 is provided by known hardware and software utilities. Also as illustrated in FIG. 1 a , one aspect of the system of the present invention includes an email protocol translator 308 . The email protocol translator 308 is a known utility which permits the web server 106 and the email server or message server 306 to communicate by translating messages sent by the web server 106 to the particular email protocol understood by the email server or message server 306 such as for example POP3 or IMAP4. Also as illustrated in FIG. 1 a , another aspect of the system of the present invention includes a known message storage/database server 315 . The message storage/database server 315 stores and delivers user credentials and secure messages in a manner that is well known. The message storage/database server 315 is also provided by known hardware and software utilities. The web server 106 , the web application 16 , and the email protocol translator 308 are used to support browser-based encryption and/or decryption of S/MIME messages in the browser as described in the Co-Pending patent applications. The roaming key server 310 is used to store and provision private keys to enrolled users (supporting user mobility) and private message keys for non-enrolled users for the encryption and/or decryption of non-enrolled users for the encryption and/or decryption of S/MIME messages in the browser as described in the Co-Pending patent applications. Normally, private keys are stored on users' desktop computers for use with email client software. However, browser based email allows the user to send or retrieve email from any device with a standard browser. The roaming key server 310 stores and provisions private message keys for use by non-enrolled recipients for decrypting secure messages (as particularized below). In one particular embodiment of the invention, the email server 306 or the message storage/database server 315 is used to store encrypted messages for non-enrolled recipients. In either case, the message storage/database server 315 can be used to store the shared secret for authenticating non-enrolled recipients. The trusted intermediary 316 cooperates with the web server 106 and the web application 16 to authenticate non-enrolled recipients, and in one embodiment of the present invention, upon provision by the recipient of the correct shared secret, decrypt the message and securely deliver the message to the non-enrolled recipient's browser. The Certificate Authority that is part of the Security Services 312 , in one particular embodiment of the present invention, is used to generate “message keys” for non-enrolled recipients. The Directory 314 illustrated in FIG. 1 a , which is part of the Certificate Authority, is used to store public keys of enrolled recipients and to search for the recipient's public keys for encrypting messages. Browser Based Creating, Signing, Encrypting and Sending Messages with Private Key Generation for Non Enrolled Recipients FIG. 2 a illustrates browser based creation and delivery of secure messages for recipients who are not enrolled in a PKI in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send an email on a secure basis (the “Sender”) requests a page on the web server 106 using the browser 20 loaded on the network-connected device 10 . The web server 106 , and specifically in co-operation with the web application 16 loaded on the web server 106 , responds to the network-connected device 10 by presenting a web page that is a web form requesting that the user associated with the network-device 10 provide authentication in order to gain access to the web application 16 , and specifically a secure message application (not shown) that is included in the web application 16 . The Sender supplies information in the authentication form fields (such as username and password) on the web page and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the web server 106 . The web server 106 in turn delivers the authentication credentials to the email server or message server 306 via the email protocol translator 308 in one embodiment of the application or authenticates the user credentials from the message storage/database server 315 in alternate embodiment of the application. Specifically in accordance with the aspect of the present invention whereby the roaming key server 310 is used to access the User Certificate and Private Key by means of the User Certificate and Private Key Store 302 , the web server 106 also transfers the user credentials to the roaming key server 310 . The email server 306 or message storage/database server 315 authenticates the Sender and then passes back, through the email protocol translator 308 , message waiting lists and other pertinent information about the Sender's email account to the web server 106 for display in the Sender's browser 20 and establishes an email session typically using a cookie, in a manner that is known. The web server 106 authenticates the Sender for the message storage/database server 315 and then passes back message waiting lists and other pertinent information about the Sender's account to the web server 106 for display in the Sender's browser 20 and establishes a session typically using a cookie, in a manner that is known. Again, in accordance with the aspect of the present invention utilizing the roaming key server 310 , the roaming key server 310 authenticates the Sender and transmits the Sender's private key and certificate through the web server 106 to the browser extension 309 . In accordance with the aspect of the present invention whereby the User Certificate and Private Key Store 302 resides on the network-connected device 10 , the private key and certificate is accessed by the browser extension 309 . The Sender prepares a message by completing the appropriate fields of a web form referred to, including for example the message subject, body and intended recipient's fields. In one particular embodiment of the present invention, the application 22 also provides the recipients' shared secret(s). The Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender address book stored on the message storage/database server 315 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either “publicly accessible” location, application 22 of the present invention is invoked to create a shared secret and generate a PKC key pair by application 22 to secure the message for non-enrolled recipients. It should be understood that the present invention refers in various places to “non-enrolled recipients”. What is meant is that the sender does not possess, or have access to, the PKI credentials of the recipient, whether the recipient has been enrolled in a PKI or not. In other words, “non-enrolled recipients” also means “non-credentialed recipients”. The private key(s) of the key pair is encrypted in a manner that is well known using the shared secret(s) as the pass phrase which is secured in a manner which is as known. The encrypted private key(s) for non enrolled recipients is(are) stored on the message storage/database server 315 along with recipient information including the shared secret question which the recipient must answer FIG. 5 . Private key(s) storage is not limited to the message storage/database server 315 and could use the roaming key server 310 or email server or message server 306 as alternate locations for private key storage. The message form data is passed to the application 22 , including the browser extension 309 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the recipient(s), and in one embodiment of the invention to form an S/MIME compliant email message. The message is returned to the browser 20 and sent from the browser 20 to the web server 106 , and using the email protocol translator 308 to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. Client Based Creating, Signing, Encrypting and Sending Messages with Private Key Generation for Non Enrolled Recipients FIG. 2 a illustrates client based creation and delivery of secure messages for recipients who are not enrolled in a PKI in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send a message on a secure basis (the “Sender”) invokes the client application 40 (as stated earlier, consisting of a known communication utility such as an email program) loaded on the network-connected device 10 . The Sender supplies authentication information (such as a username and password) and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. Often email client programs are set up such that user authentication is configured in the email client program to automate the authentication process such that it does not require user intervention. The authentication credentials are passed to the email server or message server 306 . The email server or message server 306 authenticates the Sender and then passes back message waiting lists and other pertinent information about the Sender's email account for display in the Sender's client application 40 in a manner that is known. The Sender prepares a message by completing the appropriate fields of the email message form referred to, including for example the message subject, body and intended recipient(s) fields. Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender's address book stored on the communication utility consisting of the email client program 40 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret as illustrated in FIGS. 4 and 5 to generate a PKC key pair to secure the message for non-enrolled recipients. The private key(s) of the key pair are encrypted in a manner that is well known using the shared secret(s) as the pass phrase. The encrypted private key(s) for non enrolled recipients is (are) stored on the message storage/database server 315 along with recipient information including the shared secret question which the recipient must answer as illustrated in FIG. 5 . Private key(s) storage is not limited to the message storage/database server 315 and could use the Roaming Key Server 310 or the email server or message server 306 as alternate locations for private key storage. The message form data is passed to the application 22 , including the email client extension 409 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the Recipient(s), and in one embodiment of the invention to form an S/MIME compliant email message. The message is sent from the client to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve same. Browser Based Retrieving and Decrypting an Encrypted Message from an Email or Message by Non-enrolled Recipients FIG. 3 a illustrates browser based receipt, verification, decryption and display of an encrypted message from an email server or message server 306 or message storage/database server 315 in accordance with the present invention. A non-enrolled user associated with a network-connected device 10 who desires to display an encrypted message or S/MIME email that they have received on a secure basis (the “Recipient”) requests a page from the web application 16 using the browser 20 loaded on the network-connected device 10 . The web application 16 detects if the browser extension 309 is available on the network-connected device 10 . If the browser extension 309 is not available, the web application 16 automatically downloads and installs the browser extension 309 . When the browser extension 309 is available on the network-connected device 10 the recipient's authentication credentials are passed to the browser extension 309 in accordance with the aspect of the present invention whereby message storage/database server 315 or in another embodiment, the roaming key server 310 is used to store the non-enrolled User's Private Key Store 302 which then downloads a copy of the encrypted private key to the browser extension 309 , and for non-enrolled users the question associated with the shared secret pass phrase. The browser extension 309 requests the non-enrolled Recipient to provide authentication and for an answer to the shared secret question, in order to decrypt and display the encrypted message or S/MIME email message. The Recipient supplies password or shared secret information in response to the authentication request ( FIG. 5 ) to the browser extension 309 and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the browser extension 309 in accordance with this aspect of the present invention. The application 22 authenticates against its User Certificate and Private Key Store 302 and if the provided pass phrase is correct, the private key is released to the browser extension 309 component thereof where upon the message signature can be verified and the message decrypted for display in the Recipient's browser 20 . Client Based Creating, Signing, Encrypting and Sending Messages for Non Enrolled Recipients Using a Trusted Intermediary FIG. 7 a illustrates client based creation and delivery of secure messages for recipients who are not enrolled in a PKI using a trusted intermediary 316 in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send a message on a secure basis (the “Sender”) invokes a client program loaded on the network-connected device 10 . In a preferred embodiment of the present invention the client program would be an email client program such as Microsoft OUTLOOK EXPRESS™. The Sender supplies authentication information (such as username and password) and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. Often email client programs are set up such that user authentication is configured in the email client to automate the authentication process such that it does not require user intervention. The authentication credentials are passed to the email server or message server 306 . The email server or message server 306 authenticates the Sender and then passes back, message waiting lists and other pertinent information about the Sender's email account for display in the Sender's email client 40 in a manner that is known. The Sender prepares a message by completing the appropriate fields of the email client email form referred to, including for example the message subject, body and intended recipients fields. The Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender's address book stored on the email client 40 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret ( FIGS. 4 and 5 ) and retrieves the key pair of the trusted intermediary 316 to secure the message for non-enrolled recipients. The recipient information for non-enrolled recipients including the shared secret question which the recipient must answer ( FIG. 5 ) is(are) stored on the message storage/database server 315 . The message form data is passed to the application 22 , including the email client extension 409 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the Recipient(s) and the trusted intermediary 316 for non enrolled recipients, in one embodiment of the invention to form an S/MIME compliant email message. The message is sent from the client to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. In another embodiment, and for reasons of scaleability and efficiency of the encryption algorithm, the secured message for non-enrolled recipients is decrypted by the trusted intermediary 315 , the digital signature is verified, and the message is re-encrypted using a symmetric key unique to the trusted intermediary 316 and stored to the message storage/database server 315 with a copy of the original message stored to a message archive. Client Based Retrieving and Decrypting an Encrypted Message from an Email or Message by Non Enrolled Recipients FIG. 3 b illustrates client based receipt, verification, decryption and display of an encrypted message from an email server or message server 306 or message storage/database server 315 in accordance with the present invention. There are three components required to view and encrypted message: the encrypted message, the client extension 409 and the non-enrolled recipient's private key. The method by which the non-enrolled recipient accesses these components can range from providing a link in an standard email message for the non-enrolled user to access the components as described in the previous section concerning browser based access, to providing all three components as attachments to a standard message as depicted in FIG. 3 b or any combination of the two approaches. As depicted in FIG. 3 b , a non-enrolled user associated with a network-connected device 10 who desires to display an encrypted message that they have received on a secure basis (the “Recipient”) first installs the client extension 409 . When the client extension 409 is available on the network-connected device 10 , the Recipient invokes the decryption process and the encrypted private key for the secure message is passed to the client extension 409 in accordance with this aspect of the present invention. The client extension 409 requests the non-enrolled Recipient to provide the pass phrase in order to decrypt and display the encrypted message. The non-enrolled Recipient supplies the client extension 409 shared secret information in response to the shared secret request ( FIG. 5 ) to the client extension 409 and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The private key is then passed to the client extension 409 in accordance with this aspect of the present invention where upon the message signature can be verified and the message decrypted for display in the client application 40 . In another aspect of the present invention, the persistent field level encryption disclosed in the patent and Co-Pending patent applications is used for the purposes of the present invention to maintain the confidentiality of the identities of users (and for example their clients with whom they communicate on a secure basis) in accordance with the present invention and other personal information, by encrypting related data and storing the data in an encrypted form at a database (not shown) associated with the web server 106 . The system of the present invention is best understood as the overall system including the network connected device 10 and the resources thereof, including the application 22 , and also the web server 106 and the email server or message server 306 , the message/database storage server 315 as well as the resources of these as well. The computer program of the present invention is the application 22 on the one hand, but also the web application 16 , on the other. Another aspect of the present invention includes the remote key server 310 . FIG. 6 illustrates the interactions involved in signing and encrypting messages in relation to the various components of the PKI infrastructure. A user associated with a network-connected device 10 who desires to create and send an email on a secure basis (the “Sender”) signs on to the web server 106 using the browser 20 loaded on the network-connected device 10 . The web server 106 , and specifically in co-operation with the web application 16 loaded on the web server 106 , responds to the network-connected device 10 by presenting a web page that is a web form requesting that the user associated with the network-device 10 provide authentication in order to gain access to the web application 16 , and specifically a secure message application (not shown) that is included in the web application 16 . The Sender supplies information in the authentication form fields (such as username and password) on the web page and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the web server 106 . The web server 106 in turn delivers the authentication credentials to the email server or message server 306 via the email protocol translator 308 in one embodiment of the application or authenticates user credential for the message storage/database server 315 in an alternate embodiment of the application. Specifically in accordance with the aspect of the present invention whereby the roaming key server 310 is used to access the User Certificate and Private Key from the User Certificate and Private Key Store 302 , the web server 106 also transfers the user credentials to the roaming key server 310 . The email server or message server 306 authenticates the Sender and then passes back, through the email protocol translator 308 , message waiting lists and other pertinent information about the Sender's email account to the web server 106 for display in the Sender's browser 20 and establishes an email session typically using a cookie, in a manner that is known. The web server 106 authenticates the Sender for the message storage/database server 315 and then passes back message waiting lists and other pertinent information about the Sender's account to the web server 106 for display in the Sender's browser 20 and establishes a session typically using a cookie, in a manner that is known. Again, in accordance with the aspect of the present invention utilizing the roaming key server 310 , the roaming key server 310 authenticates the Sender and transmits the Sender's private key and certificate through the web server 106 to the browser extension 309 . In accordance with the aspect of the present invention whereby the User Certificate and Private Key Store 302 resides on the network-connected device 10 , the private key and certificate is accessed by the browser extension 304 . The Sender prepares a message by completing the appropriate fields of the web form referred to, including for example the message subject, body and intended recipient(s) fields. In one particular embodiment of the present invention, the application 22 also provides the recipient(s) the shared secret(s). Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are retrieved and optionally verified from the associated directory 314 or from the sender address book stored on the message storage/database server 315 . In the event that the recipient(s)' public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret ( FIG. 4 ) and retrieves the PKC key pair of the trusted intermediary 316 by application 22 to secure the message for non-enrolled recipients. The recipient information for non-enrolled recipients including the shared secret question which the recipient must answer ( FIG. 5 ) is (are) sent by the sender and stored on the message storage/database server 315 . The message form data is passed to the application 22 , including the browser extension 309 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the recipient(s) and trusted intermediary 316 for non-enrolled recipients, in one embodiment of the invention to form an S/MIME compliant email message. The message is returned to the browser 20 and sent from the browser 20 to the web server 106 , and using the email protocol translator 308 to the email server or message server 306 for forwarding to the identified recipients in one embodiment of the invention. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. In another embodiment, and for reasons of scaleability and efficiency of the encryption algorithm, the secured message for non-enrolled recipients is decrypted by the trusted intermediary 316 , the digital signature is verified, and the message is re-encrypted using a symmetric key unique to the trusted intermediary 316 and stored to the message storage/database server 315 (with an optional copy of the original message stored to a message archive). The method of the present invention is best understood as a process for exchanging PKI encrypted messages and S/MIME messages through a browser, whether a web browser or WAP browser or message client whether personal computer based or wireless device based, for recipients who are not enrolled in a PKI or where the sender does not have access to the PKI credentials of the recipient. The method of the present invention should also be understood as a method for integrating wireless devices with Internet secure messaging using S/MIME or PKI based message encryption for non-enrolled recipients. Another aspect of the method of the present invention is a method for delivering private keys to non-enrolled recipients, through the Internet or a wireless network. Yet another aspect of the method of the present invention, is a method for eliminating the “man in the middle” security hole of proxy based gateways between the Internet and wireless networks by providing persistent secure data communication using S/MIME or PKI for encrypting messages. A still other aspect of the present invention is a method for allocating data resources as between the web server and a wireless device such that PKI is provided on the wireless device so as to provide encryption on a persistent basis. The present invention also provides for persistent field level encryption on a selective basis throughout an Internet-based data process. This promotes efficient utilization of resources by invoking PKI operations in relation to specific elements of an Internet-based data process where security/authentication is most needed. The present invention also provides a set of tools whereby PKI encryption and S/MIME capability is added to a browser in an efficient manner for non enrolled recipients. The present invention should also be understood as a set of tools for complying with legal digital signature requirements, including in association with a wireless device using a web email or client based email system incorporating S/MIME for non-enrolled recipients.

A system for encrypting and decrypting messages using a browser in either a web or wireless device or secure message client software for transmission to or from a web server on the Internet connected to an email server or message server for the situation where the sender does not possess the credentials and public key of the recipients. The encryption and decryption is conducted using a standard web browser on a personal computer or a mini browser on a wireless device, or message client software on either a personal computer or wireless devices such that messages transmitted to the web or wireless browser or message client software can be completed and encrypted and signed by the user such that encrypted and signed data does not require credentials and public key of the recipients. A method for delivering and using private keys to ensure that such keys are destroyed after use is also provided. A method of transmitting encrypted messages to a web or wireless browser or message client and decrypting and verifying such messages by recipients who do not possess or who are not enrolled in a PKI and do not have private keys. A method for authenticating the sender/user of the browser, and a method for accessing or generating public and private keys for encrypting and decrypting messages for recipients who are not enrolled in a public key infrastructure.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present disclosure is related to air conditioning systems. More particularly, the present disclosure is related to methods and systems for controlling air conditioning systems having a free-cooling mode and a cooling mode. [0003] 2. Description of Related Art [0004] During the typical operation of air conditioning systems, the system is run in a cooling mode wherein energy is expended by operating a compressor. The compressor compresses and circulates a refrigerant to chill or condition a working fluid, such as air or other secondary loop fluid (e.g., chilled water or glycol), in a known manner. The conditioned working fluid can then be used in a refrigerator, a freezer, a building, an automobile, and other spaces with climate controlled environment. [0005] However, when the outside ambient temperature is low, there exists the possibility that the outside ambient air itself may be utilized to provide cooling to the working fluid without engaging the compressor. When the outside ambient air is used by an air conditioning system to condition the working fluid, the system is referred to as operating in a free-cooling mode. [0006] As noted above, traditionally, even when the ambient outside air temperature is low, the air conditioning system is run in the cooling mode. Running in cooling mode under such conditions provides a low efficiency means of conditioning the working fluid. In contrast, running the air conditioning system under such conditions in a free-cooling mode is more efficient. In the free-cooling mode, one or more ventilated heat exchangers and pumps are activated so that the refrigerant is circulated by the pumps and is cooled by the outside ambient air. In this manner, the refrigerant, cooled by the outside ambient air, can be used to cool the working fluid without the need for the low efficiency compressor. [0007] Accordingly, it has been determined by the present disclosure that there is a need for methods and systems that improve the efficiency of air conditioning systems having a free-cooling mode. BRIEF SUMMARY OF THE INVENTION [0008] An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode. [0009] A method of controlling an air conditioning system having a cooling mode and a free-cooling mode is provided. The method includes switching the air conditioning system to the free-cooling mode; initiating a recover-refrigerant sequence to recover refrigerant from a portion of a refrigeration circuit that is not used during the free-cooling mode but is used during the cooling mode; and maintaining the air conditioning system in the free-cooling mode after completion of the recover-refrigerant sequence. [0010] The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0011] FIG. 1 is an exemplary embodiment of an air conditioning system in cooling mode according to the present disclosure; [0012] FIG. 2 is an exemplary embodiment of an air conditioning system in free-cooling mode according to the present disclosure; and [0013] FIG. 3 illustrates an exemplary embodiment of a method of operating the air conditioning system of FIGS. 1 and 2 according to the present disclosure. [0014] FIG. 4 illustrates a graph of an exemplary embodiment of the refrigerant recovery sequence according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION [0015] Referring now to the drawings and in particular to FIGS. 1 and 2 , an exemplary embodiment of an air conditioning system (“system”) according to the present disclosure, generally referred to by reference numeral 10 , is shown. System 10 is configured to operate in a cooling mode 12 ( FIG. 1 ) and a free-cooling mode 14 ( FIG. 2 ). [0016] System 10 includes a controller 16 for selectively switching between cooling and free-cooling modes 12 , 14 . Advantageously, controller 16 includes a refrigerant-recovery sequence 18 (“sequence”) resident thereon that monitors pressure in system 10 during the switchover from cooling mode 12 to free-cooling mode 14 . In this manner, system 10 recovers refrigerant from system 10 components that are used in cooling mode 12 , but not in free-cooling mode 14 . This allows the pump to operate during the initiation of free-cooling mode 14 and improves pump reliability. [0017] System 10 also includes a refrigeration circuit 20 that includes a condenser 22 , a pump 24 , an expansion device 26 , an evaporator 28 , and a compressor 30 . Controller 16 is configured to selectively control either compressor 30 (when in cooling mode 12 ) or pump 24 (when in free-cooling mode 14 ) to circulate a refrigerant through system 10 in a flow direction (D). Thus, system 10 , when in cooling mode 12 , controls compressor 30 to compress and circulate the refrigerant in flow direction 30 . However, system 10 , when in free-cooling mode 14 , controls pump 24 to circulate the refrigerant in flow direction 30 . As such, free-cooling mode 14 uses less energy then cooling mode 12 since the free-cooling mode does not require the energy expended by compressor 30 . Moreover, System 10 includes a suction pressure sensor 49 and a discharge pressure sensor 51 . [0018] System 10 includes a compressor by-pass loop 32 and a pump by-pass loop 34 . System 10 includes one or more valves 36 - 1 , 36 - 2 , and 36 - 3 . In one embodiment of the present disclosure valve 36 - 3 is a three-way valve. Valves 36 are controlled by controller 16 in a known manner. Thus, controller 16 can selectively position valves 36 to selectively open and close by-pass loops 32 , 34 as desired. [0019] In cooling mode 12 , controller 16 controls valves 36 so that compressor by-pass loop 32 is closed and pump by-pass loop 34 is open. In this manner, system 10 is configured to allow compressor 30 to compress and circulate refrigerant in the flow direction D by flowing through pump by-pass loop 34 . [0020] In contrast, controller 16 , when in free-cooling mode 14 , controls valves 36 so that compressor by-pass loop 32 is open and pump by-pass loop 34 is closed. In this manner, system 10 is configured to allow pump 24 to circulate refrigerant in the flow direction D by flowing through compressor by-pass loop 32 . [0021] Accordingly, system 10 can condition (i.e., cool and/or dehumidify) a working fluid 38 in heat-exchange communication with evaporator 28 in both cooling and free-cooling modes 12 , 14 . Working fluid 38 can be ambient indoor air or a secondary loop fluid such as, but not limited to, chilled water or glycol. [0022] In cooling mode 12 , system 10 operates as a standard vapor-compression air conditioning system known in the art where the compression and expansion of refrigerant via expansion device 26 are used to condition working fluid 38 . Expansion device 26 can be any known controllable expansion device such as, but not limited to a thermal expansion valve. [0023] In free-cooling mode 14 , system 10 takes advantage of the heat removing capacity of outdoor ambient air 40 , which is in heat exchange relationship with condenser 22 via one or more fans 42 , to condition working fluid 38 . [0024] Although system 10 is described herein as a conventional air conditioning (cooling) system, one skilled in the art will recognize that system 10 may also be configured as a heat pump system to provide both heating and cooling, by adding a reversing valve (not shown) so that condenser 22 (i.e., the outdoor heat exchanger) functions as an evaporator in the heating mode and evaporator 28 (i.e., the indoor heat exchanger) functions as a condenser in the heating mode. [0025] It has been determined by the present disclosure that refrigerant leaving condenser 22 can be in one of several different phases, namely a gas phase, a liquid-gas phase, or a liquid phase. When controller 16 switches system 10 to free-cooling mode 14 , pump 24 is supplied with refrigerant in the different phases until the system reaches a state of equilibrium in full circuit. [0026] After controller 16 initiates free-cooling mode 14 and during the time it takes for system 10 to reach equilibrium, pump 24 is supplied with refrigerant in the different phases. Unfortunately, when pump 24 is supplied with refrigerant in the gas or liquid-gas phases, the pump does not operate as desired. Moreover, the gas phase and/or liquid-gas phase refrigerant can cause pump 24 to cavitate, which can damage the pump and/or the pump motor (not shown). [0027] Turning off pump 24 would stop the potential damage from such cavitation, but also would result in delaying the ability for system 10 to easily switch from cooling mode 12 to free-cooling mode 14 . Advantageously, controller 16 includes sequence 18 that functions to recover refrigerant from system 10 components that are not used during free-cooling mode 14 during the time when system 10 switches out of cooling mode 12 and into free-cooling mode 14 . [0028] System 10 includes a first pressure sensor 44 , a second pressure sensor 46 , a suction pressure sensor 49 , and a discharge pressure sensor 51 in electrical communication with controller 16 . First pressure sensor 44 is positioned at an entrance 48 - 1 of pump 24 , while second pressure sensor 46 is positioned at an exit 48 - 2 of the pump. Controller 16 uses the pressures measured by first and second sensors 44 , 46 to determine a pump pressure difference in real-time. Moreover, controller 16 operates compressor 30 , adjusts the positions of expansion device 26 and valves 36 , and monitors the pressure recorded by a third pressure sensor 49 during the switchover from cooling mode 12 to free-cooling mode 14 . [0029] The operation of sequence 18 is described in more detail with reference to FIG. 3 . FIG. 3 illustrates an exemplary embodiment of a method 50 of controlling system 10 having recover refrigerant in sequence 18 according to the present disclosure. [0030] Method 50 , when system 10 is operating in cooling mode 12 , includes a first free cooling determination step 54 . During first free cooling determination step 54 , method 50 determines whether the temperature of ambient air 40 is sufficient for system 10 to switch to free-cooling mode 14 . If so, method 50 then performs a free-cooling capacity check step 56 wherein system 10 is checked to determine if there is sufficient capacity to operate system 10 in free-cooling mode 14 . If so, method 50 then performs sequence 18 . [0031] Sequence 18 includes a system pump down step 60 and a low pressure equalization step 62 . Initially during sequence 18 , valve 36 - 3 is in a position in accordance with cooling mode 12 , pump 24 is off, and compressor 30 is turned off. [0032] In pump down step 60 , expansion device 26 is closed and compressor 30 is turned on. Compressor 30 remains turned on while a pressure measured by suction pressure sensor 49 is greater than a suction pressure threshold. Compressor 30 is turned off when the pressure measured by suction pressure sensor 49 is less than the suction pressure threshold. There is a pressure differential (“DP”) between suction pressure sensor 49 and discharge pressure sensor 51 . [0033] In equalization sequence 62 , compressor 30 is turned off. When DP is greater than a threshold pressure differential (“DP-threshold”), expansion device 26 is opened at a minimum rate. In one embodiment of the present disclosure, expansion device 26 is positioned approximately 10 percent of a full open position. Expansion device 26 will then close when DP is less than DP-threshold. [0034] Referring now to FIG. 4 , a graph illustrating an exemplary embodiment of sequence 18 according to the present disclosure is shown. As can be seen, system 10 runs in free-cooling capacity check step 56 for approximately eight seconds, wherein sequence 18 is initiated. In sequence 18 , initially, valve 36 - 3 is in a position in accordance with cooling mode 12 , pump 24 is off, and compressor 30 is turned off. During pump down step 60 , expansion device 26 is closed, and compressor 30 is turned on until DP equals approximately 1500 kPa. Equalization sequence 62 is then initiated, wherein expansion device 26 is opened at a minimum while DP is greater than DP-Threshold. In the illustrated embodiment, it is seen that as DP approaches DP-Threshold, the percent opening rate of expansion device 26 decreases to a value of about 3 percent opening rate. [0035] Advantageously, it has been determined by the present disclosure that sequence 18 ensures that there is sufficient compressed refrigerant in liquid form for pump 24 to operate. This improves the reliability of pump 24 when system 10 switches into free-cooling mode 14 . [0036] After sequence 18 has been performed, method 50 switches system 10 into free cooling mode 14 at a free-cooling switching step 64 . [0037] It should be recognized that method 50 is described herein by way of example in use while system 10 is operating in cooling mode 12 . Of course, it is contemplated by the present disclosure for method 50 to find equal use when system 10 is stopped such that sequence 18 avoids pump cavitation during start-up of system 10 into free-cooling mode 14 from a stopped state. [0038] After free-cooling switching step 64 , method 50 includes a pump priming step 66 . After pump 24 has been primed by step 66 , method 50 runs in free-cooling mode 14 at step 68 . System 10 continues to run in free-cooling mode 14 until either controller 16 determines that there is a lack of system capacity at a second capacity determination step 70 or determines that pump 24 is defusing or cavitating at a pump protection step 72 . If either of these conditions are determined to be present, method 50 switches system 10 into cooling mode 12 at a cooling mode switching step 74 . [0039] It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated. [0040] While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 11/692,159, filed Mar. 27, 2007, which is a continuation of U.S. patent application Ser. No. 11/059,216, filed Feb. 15, 2005, now U.S. Pat. No. 7,197,611, which is a continuation of U.S. patent application Ser. No. 10/128,167, filed Apr. 22, 2002, now U.S. Pat. No. 6,868,474, which is a divisional of U.S. patent application Ser. No. 09/169,206, filed Oct. 9, 1998, now U.S. Pat. No. 6,401,167, which claims priority to U.S. Provisional Patent Application No. 60/061,770, filed Oct. 10, 1997, all of which are herein incorporated by referenced in their entirety. FIELD OF THE INVENTION [0002] The present invention relates generally to electronic systems for data storage and retrieval. More particularly, the invention is directed toward improved methods and structures for memory devices. BACKGROUND OF THE INVENTION [0003] In any engineered design there are compromises between cost and performance. The present invention introduces novel methods and structures for reducing the cost of memory devices while minimally compromising their performance. The description of the invention requires a significant amount of background including: application requirements, memory device physical construction, and memory device logical operation. [0004] Memory device application requirements can be most easily understood with respect to memory device operation. FIG. 1 shows the general organization of a memory device. Memory device 101 consists of a core 102 and an interface 103 . The core is responsible for storage of the information. The interface is responsible for translating the external signaling used by the interconnect 105 to the internal signaling carried on bus 104 . The primitive operations of the core include at least a read operation. Generally, there are other operations required to manage the state of the core 102 . For example, a conventional dynamic random access memory (DRAM) has at least write, precharge, and sense operations in addition to the read operation. [0005] For purposes of illustrating the invention a conventional DRAM core will be described. FIG. 2 is a block diagram of a conventional DRAM core 102 . Since the structure and operation of a conventional DRAM core is well known in the art only a brief overview is presented here. [0006] A conventional DRAM core 202 mainly comprises storage banks 211 and 221 , row decoder and control circuitry 210 , and column data path circuit comprising column amplifiers 260 and column decoder and control circuitry 230 . Each of the storage banks comprises storage arrays 213 and 223 and sense amplifiers 212 and 222 . [0007] There may be many banks, rather than just the two illustrated. Physically the row and column decoders may be replicated in order to form the logical decoder shown in FIG. 2 . The column i/o lines 245 may be either bidirectional, as shown, or unidirectional, in which case separate column i/o lines are provided for read and write operations. [0008] The operation of a conventional DRAM core is divided between row and column operations. Row operations control the storage array word lines 241 and the sense amplifiers via line 242 . These operations control the movement of data from the selected row of the selected storage array to the selected sense amplifier via the bit lines 251 and 252 . Column operations control the movement of data from the selected sense amplifiers to and from the external data connections 204 d and 204 e. [0009] Device selection is generally accomplished by one of the following choices: matching an externally presented device address against an internally stored device address; requiring separate operation control lines, such as RAS and CAS, for each set of memory devices that are to be operated in parallel; and providing at least one chip select control on the memory device. [0013] FIG. 3 illustrates the timing required to perform the row operations of precharge and sense. In their abstract form these operations can be defined as precharge(device, bank)—prepare the selected bank of the selected device for sensing; and sense(device, bank, row)—sense the selected row of the selected bank of the selected device. [0016] The operations and device selection arguments are presented to the core via the PRECH and SENSE timing signals while the remaining arguments are presented as signals which have setup and hold relationships to the timing signals. Specifically, as shown in FIGS. 2-4 , PRECH and PRECHBANK form signals on line 204 a in which PRECHBANK presents the “bank” argument of the precharge operation, while SENSE, SENSEBANK and SENSEROW form signals on line 204 b in which SENSEBANK and SENSEROW present the “bank” and “row” arguments, respectively, for the sense operation. Each of the key primary row timing parameters, t RP , t RAS,min , and t RCD can have significant variations between devices using the same design and across different designs using the same architecture. [0017] FIG. 5 and FIG. 6 illustrate the timing requirements of the read and write operations, respectively. These operations can be defined abstractly as: data=read(device, bank, column)—transfer the data in the subset of the sense amplifiers specified by “column” in the selected “bank” of the selected “device” to the READDATA lines; and write (device, bank, column, mask, data)—store the data presented on the WRITEDATA lines into the subset of the sense amplifiers specified by “column” in the selected “bank” of the selected “device”; optionally store only a portion of the information as specified by “mask”. [0020] More recent conventional DRAM cores allow a certain amount of concurrent operation between the functional blocks of the core. For example, it is possible to independently operate the precharge and sense operations or to operate the column path simultaneously with row operations. To take advantage of this concurrency each of the following groups may operate somewhat independently: PRECH and PRECHBANK on lines 204 a; SENSE, SENSEBANK, and SENSEROW on lines 204 b; COLCYC 204 f on line, COLLAT and COLADDR on lines 204 g , WRITE and WMASK one lines 204 c , READDATA on line 204 d , and WRITEDATA on line 204 . [0024] There are some restrictions on this independence. For example, as shown in FIG. 3 , operations on the same bank observe the timing restrictions of t RP and t RAS,min . If accesses are to different banks, then the restrictions of FIG. 4 for t SS and t PP may have to be observed. [0025] The present invention, while not limited by such values, has been optimized to typical values as shown in Table 1. TABLE 1 Typical Core Timing Values Symbol Value (ns) t RP 20 t RAS, Min 50 t RCD 20 t PP 20 t SS 20 t PC 10 t DAC 7 [0026] FIG. 7 shows the permissible sequence of operations for a single bank of a conventional DRAM core. It shows the precharge 720 , sense 721 , read 722 , and write 723 , operations as nodes in a graph. Each directed arc between operations indicates an operation which may follow. For example, arc 701 indicates that a precharge operation may follow a read operation. [0027] The series of memory operations needed to satisfy any application request can be covered by the nominal and transitional operation sequences described in Table 2 and Table 3. These sequences are characterized by the initial and final bank states as shown in FIG. 8 . [0028] The sequence of memory operations is relatively limited. In particular, there is a universal sequence: [0029] precharge, [0030] sense, [0031] transfer (read or write), and [0032] close. [0033] In this sequence, close is an alternative timing of precharge but is otherwise functionally identical. This universal sequence allows any sequence of operations needed by an application to be performed in one pass through it without repeating any step in that sequence. A control mechanism that implements the universal sequence can be said to be conflict free. A conflict free control mechanism permits a new application reference to be started for every minimum data transfer. That is, the control mechanism itself will never introduce a resource restriction that stalls the memory requester. There may be other reasons to stall the memory requester, for example references to different rows of the same bank may introduce bank contention, but lack of control resources will not be a reason for stalling the memory requestor TABLE 2 Nominal Transactions Initial Final Transaction Operations Bank State Bank State Type Performed closed closed empty sense, series of column operations, precharge open open miss precharge, sense, series of column operations hit series of column operations [0034] TABLE 3 Transitional Transactions Initial Final Transaction Operations Bank State Bank State Type Performed closed open empty sense, <series of column operations>(optional) open closed miss <precharge, sense, series of column operations>(optional), precharge hit <series of column operations> (optional), precharge [0035] Memory applications may be categorized as follows: main memory—references generated by a processor, typically with several levels of caches; graphics—references generated by rendering and display refresh engines; and unified—combining the reference streams of main memory and graphics. [0039] Applications may also be categorized by their reference stream characteristics. According to the application partition mentioned above reference streams can be characterized in the following fashion: First, main memory traffic can be cached or uncached processor references. Such traffic is latency sensitive since typically a processor will stall when it gets a cache miss or for any other reason needs data fetched from main memory. Addressing granularity requirements are set by the transfer size of the processor cache which connects to main memory. A typical value for the cache transfer size is 32 bytes. Since multiple memory interfaces may run in parallel it is desirable that the memory system perform well for transfer sizes smaller than this. Main memory traffic is generally not masked; that is, the vast bulk of its references are cache replacements which need not be written at any finer granularity than the cache transfer size. Another type of reference stream is for graphics memory. Graphics memory traffic tends to be bandwidth sensitive rather than latency sensitive. This is true because the two basic graphics engines, rendering and display refresh, can both be highly pipelined. Latency is still important since longer latency requires larger buffers in the controller and causes other second order problems. The ability to address small quanta of information is important since typical graphics data structures are manipulated according to the size of the triangle being rendered, which can be quite small. If small quanta cannot be accessed then bandwidth will be wasted transferring information which is not actually used. Traditional graphics rendering algorithms benefit substantially from the ability to mask write data; that is, to merge data sent to the memory with data already in the memory. Typically this is done at the byte level, although finer level, e.g. bit level, masking can sometimes be advantageous. [0042] As stated above, unified applications combine the characteristics of main memory and graphics memory traffic. As electronic systems achieve higher and higher levels of integration the ability to handle these combined reference streams becomes more and more important. [0043] Although the present invention can be understood in light of the previous application classification, it will be appreciated by those skilled in the art that the invention is not limited to the mentioned applications and combinations but has far wider application. In addition to the specific performance and functionality characteristics mentioned above it is generally important to maximize the effective bandwidth of the memory system and minimize the service time. Maximizing effective bandwidth requires achieving a proper balance between control and data transport bandwidth. The control bandwidth is generally dominated by the addressing information delivered to the memory device. The service time is the amount of time required to satisfy a request once it is presented to the memory system. Latency is the service time of a request when the memory system is otherwise devoid of traffic. Resource conflicts, either for the interconnect between the requester and the memory devices, or for resources internal to the memory devices such as the banks, generally determine the difference between latency and service time. It is desirable to minimize average service time, especially for processor traffic. [0044] The previous section introduced the performance aspects of the cost-performance tradeoff that is the subject of the present invention. In this section the cost aspects are discussed. These aspects generally result from the physical construction of a memory device, including the packaging of the device. [0045] FIG. 9 shows the die of a memory device 1601 inside of a package 1620 . For typical present day device packages, the bond pads, such as 1610 , have center to center spacing significantly less than the pins of the device, such as 1640 . This requires that there be some fan-in from the external pins to the internal bonding pads. As the number of pads increases the length of the package wiring, such as 1630 , grows. Observe that elements 1630 and 1640 are alternately used to designate package wiring. [0046] There are many negative aspects to the increase in the length of the package wiring 1640 , including the facts that: the overall size of the package increases, which costs more to produce and requires more area and volume when the package is installed in the next level of the packaging hierarchy, such as on a printed circuit board. Also, the stub created by the longer package wiring can affect the speed of the interconnect. In addition, mismatch in package wiring lengths due to the fan-in angle can affect the speed of the interconnect due to mismatched parasitics. [0047] The total number of signal pins has effects throughout the packaging hierarchy. For example, the memory device package requires more material, the next level of interconnect, such as a printed circuit board, requires more area, if connectors are used they will be more expensive, and the package and die area of the master device will grow. [0048] In addition to all these cost concerns based on area and volume of the physical construction another cost concern is power. Each signal pin, especially high speed signal pins, requires additional power to run the transmitters and receivers in both the memory devices as well as the master device. Added power translates to added cost since the power is supplied and then dissipated with heat sinks. [0049] The memory device illustrated in FIG. 10 uses techniques typical of present day memory devices. In this device 1701 , a single shared command bus 1710 in conjunction with the single address bus 1720 and mask bus 1730 is used to specify all of the primitive operations comprising precharge, sense, read, and write in addition to any other overhead operations such as power management. [0050] FIG. 11 illustrates the operation of the memory device of FIG. 10 . The illustrated reference sequence, when classified according to Table 2 and the universal sequence previously described comprises: write empty—sense 1851 , write 1853 with mask 1871 , data 1881 , close(precharge) 1861 ; write miss—precharge 1852 , sense 1854 , write 1856 with mask 1872 , data 1882 ; read hit—read 1857 , tristate control 1873 , data 1883 ; and transitional write miss—precharge 1855 , sense 1858 , write 1859 , mask 1874 , data 1884 , close(precharge) 1862 . [0055] In FIG. 11 each box represents the amount of time required to transfer one bit of information across a pin of the device. [0056] In addition to illustrating a specific type of prior art memory device, FIG. 11 can be used to illustrate a number of techniques for specifying data transfers. One prior art technique uses an internal register to specify the number of data packets transferred for each read or write operation. When this register is set to its minimum value and the reference is anything besides a hit then the device has insufficient control bandwidth to specify all the required operations while simultaneously keeping the data pins highly utilized. This is shown in FIG. 11 by the gaps between data transfers. For example there is a gap between data a, 1881 and data b, 1882 . Even if sufficient control bandwidth were provided some prior art devices would also require modifications to their memory cores in order to support high data pin utilization. [0057] The technique of specifying the burst size in a register makes it difficult to mix transfer sizes unless the burst size is always programmed to be the minimum, which then increases control overhead. The increase in control overhead may be so substantial as to render the minimum burst size impractical in many system designs. [0058] Regardless of the transfer burst size, the technique of a single unified control bus, using various combinations of the command pins 1810 , address pins 1820 , and mask pins 1830 places limitations on the ability to schedule the primitive operations. A controller which has references in progress that are simultaneously ready to use the control resources must sequentialize them, leading to otherwise unnecessary delay. [0059] Read operations do not require masking information. This leaves the mask pins 1830 available for other functions. Alternately, the mask pins during read operations may specify which bytes should actually be driven across the pins as illustrated by box 1873 . [0060] Another technique is an alternative method of specifying that a precharge should occur by linking it to a read or write operation. When this is done the address components of the precharge operation need not be respecified; instead, a single bit can be used to specify that the precharge should occur. One prior art method of coding this bit is to share an address bit not otherwise needed during a read or write operation. This is illustrated by the “A-Prech” boxes, 1861 and 1862 . [0061] FIG. 12 shows a sequence of four read references each comprising all the steps of the universal sequence. Although the nominal transactions of Table 2 do not require the multiple precharge steps of the universal sequence it is useful to examine how well a device handles the universal sequence in order to understand its ability to support mixed empty and miss nominal transactions, as well as the transitional transactions of Table 3. As can be seen, the data pins are poorly utilized. This indicates that control contention will limit the ability of the device to transfer data for various mixes of application references. The utilization of the data pins could be improved by making the burst length longer. However, the applications, such as graphics applications, require small length transfers rather than large ones. [0062] Another technique makes the delay from write control information to data transfer different from the delay of read control information to data transfer. When writes and reads are mixed, this leads to difficulties in fully utilizing the data pins. [0063] Thus, current memory devices have inadequate control bandwidth for many application reference sequences. Current memory devices are unable to handle minimum size transfers. Further, current memory devices utilize the available control bandwidth in ways that do not support efficient applications. Current memory devices do not schedule the use of the data pins in an efficient manner. In addition, current memory devices inefficiently assign a bonding pad for every pin of the device. BRIEF DESCRIPTION OF THE DRAWINGS [0064] FIG. 1 illustrates a known memory structure architecture. [0065] FIG. 2 illustrates a known DRAM core structure. [0066] FIG. 3 illustrates Row Access Timing to a single bank in accordance with the prior art. [0067] FIG. 4 illustrates Row Access Timing to different banks in accordance with the prior art. [0068] FIG. 5 illustrates Column Read Timing in accordance with the prior art. [0069] FIG. 6 illustrates Column Write Timing in accordance with the prior art. [0070] FIG. 7 illustrates operation sequences for a conventional core DRAM. [0071] FIG. 8 illustrates initial and final bank states associated with a memory operation in accordance with the prior art. [0072] FIG. 9 illustrates a semiconductor packaging structure utilized in accordance with the prior art. [0073] FIG. 10 illustrates DRAM interface signals in accordance with the prior art. [0074] FIG. 11 illustrates a command control sequence in accordance with the prior art. [0075] FIG. 12 illustrates a unified control universal read sequence in accordance with an embodiment of the invention. [0076] FIG. 13 illustrates a unified control universal read sequence with mask precharge in accordance with an embodiment of the invention. [0077] FIG. 14 illustrates a unified control universal write sequence with mask precharge in accordance with an embodiment of the invention. [0078] FIG. 15 illustrates a unified control universal read write sequence with mask precharge in accordance with an embodiment of the invention. [0079] FIG. 16 illustrates a column access block diagram with no delayed write in accordance with an embodiment of the invention. [0080] FIG. 17 illustrates timing operations associated with a write command of an embodiment of the invention. [0081] FIG. 18 illustrates timing operations associated with a read command of an embodiment of the invention. [0082] FIG. 19 illustrates mixed read and write timing in accordance with an embodiment of the invention. [0083] FIG. 20 illustrates a column access with a delayed write in accordance with an embodiment of the invention. [0084] FIG. 21 illustrates mixed read and write timing in accordance with an embodiment of the invention. [0085] FIG. 22 illustrates a unified control universal read and write sequence with mask precharge and delayed write in accordance with the invention. [0086] FIG. 23 illustrates a split control universal read write sequence with mask precharge and delayed write in accordance with an embodiment of the invention. [0087] FIG. 24 illustrates a cost optimized highly concurrent memory in accordance with the invention. [0088] FIG. 25 illustrates a control packet format for encoding the sense operation on the primary control lines in accordance with an embodiment of the invention. [0089] FIG. 26 illustrates a control packet format for encoding the precharge operation on the primary control lines in accordance with an embodiment of the invention. [0090] FIG. 27 illustrates a packet format when masking is not used on the secondary control lines of the invention. [0091] FIG. 28 illustrates a packet format when masking is used on the secondary control lines of the invention. [0092] FIG. 29 illustrates a data block timing diagram for data packets transmitted on data wires of the invention. [0093] FIG. 30 illustrates a read hit in accordance with an embodiment of the invention. [0094] FIG. 31 illustrates an empty read in accordance with an embodiment of the invention. [0095] FIG. 32 illustrates a read miss in accordance with an embodiment of the invention. [0096] FIG. 33 illustrates a write hit in accordance with an embodiment of the invention. [0097] FIG. 34 illustrates an empty write in accordance with an embodiment of the invention. [0098] FIG. 35 illustrates a write miss in accordance with an embodiment of the invention. [0099] FIG. 36 illustrates reads in accordance with an embodiment of the invention. [0100] FIG. 37 illustrates empty byte masked writes in accordance with an embodiment of the invention. [0101] FIG. 38 illustrates byte masked write hits in accordance with an embodiment of the invention. [0102] FIG. 39 illustrates byte masked write misses in accordance with an embodiment of the invention. [0103] FIG. 40 illustrates reads or unmasked writes in accordance with an embodiment of the invention. [0104] FIG. 41 illustrates universal byte masked writes in accordance with an embodiment of the invention. [0105] FIG. 42 illustrates reads or unmasked writes in accordance with an embodiment of the invention. [0106] FIG. 43 illustrates reads or masked writes or unmasked writes in accordance with an embodiment of the invention. [0107] FIG. 44 illustrates reads and unmasked writes in accordance with an embodiment of the invention. [0108] FIG. 45 illustrates transfers using a primary control packet for sense and precharge in accordance with an embodiment of the invention. [0109] FIG. 46 illustrates a memory block constructed in accordance with an embodiment of the invention. [0110] FIG. 47 illustrates DRAM refresh operations utilized in connection with an embodiment of the invention. [0111] FIG. 48 illustrates isolation pins without accompanying pads in accordance with an embodiment of the invention. [0112] FIG. 49 illustrates the transport of auxiliary information in accordance with an embodiment of the invention. [0113] FIG. 50 illustrates framing of the CMD for processing by the auxiliary transport unit in accordance with an embodiment of the invention. [0114] Like reference numerals refer to corresponding parts throughout the drawings. DESCRIPTION OF EMBODIMENTS [0115] FIG. 13 shows a timing diagram according to an embodiment of the present invention in which the Mask pins 2030 carry a precharge specification rather than either the write mask information or the tristate control information, as shown in connection with FIG. 12 . This use of the Mask pins need not be exclusive. There are multiple ways in which to indicate how the information presented on the Mask pins is to be used. For example: in one embodiment according to the present invention, a register within the device specifies whether the mask pins are to be used for masking, tristate control, or precharge control; in another embodiment according to the present invention, the encoding of the command pins is extended to specify, on a per operation basis, how the mask pins are to be used; and in another embodiment according to the present invention, a register bit indicates whether tristate control is enabled or not and, in the case it is not enabled, an encoding of the command pins indicates if a write is masked or not; in this embodiment all reads and unmasked writes may use the Mask pins to specify a precharge operation while masked writes do not have this capability since the Mask pins are used for mask information [0119] There are many alternatives for how to code the precharge information on the mask pins. In one embodiment in which there are two mask pins and the memory device has two banks, one pin indicates whether an operation should occur and the other pin indicates which bank to precharge. In an alternative embodiment, in which the minimum data transfer requires more than one cycle, more banks are addressed by using the same pins for more than one cycle to extend the size of the bank address field. [0120] Using the mask pins to specify a precharge operation and the associated bank address requires another way of specifying the device argument. In one embodiment the device is specified in some other operation. For example, the precharge specified by the mask pins shares device selection with a chip select pin that also conditions the main command pins. In another embodiment, additional control bandwidth is added to the device. For example, an additional chip select pin is added for sole use by the recoded mask pin precharge. In yet another example of using additional control bandwidth in which the minimum data transfer requires more than one cycle, the device address is coded on the additional bits, the device address being compared to an internal device address register. [0121] In FIG. 13 it can be seen that the data pins are better utilized. For example, the offset between data block 1982 and 1983 in FIG. 12 is reduced from 4 units of time to the 2 units of time between data blocks 2082 and 2083 of FIG. 13 . This is accomplished because the precharge specification has been moved from the primary command pins, 2010 , to the mask pins 2030 so there is more time available on the command pins to specify the sense and read or write operations. Delaying Write Data [0122] FIG. 14 shows the timing of the universal write sequence in an embodiment according to the present invention, when the Mask pins are used for the precharge step. The offset from data block 2182 to data block 2183 is two units of time just as in the read sequence shown in FIG. 13 . However, the offset from the use of the command pins to the use of the data pins is shown as zero for the write case but three for the read case. As can be seen in FIG. 15 , when these sequences are combined to produce a sequence that has both reads and writes, there is a substantial gap between the write data and the read data as can be seen by the delay between data 2282 and data 2283 . Delaying the write data so that the offset from control information to data is the same, independent of whether the transfer is a read or a write, reduces or eliminates the delay. [0123] FIG. 16 shows the column access path of a memory device in an embodiment of the invention that does not delay write data with respect to read data. In FIG. 16 , the delay from external control 2304 to internal column control 2306 is identical whether the access is a read or a write. As can be seen from FIG. 5 and FIG. 6 , this means that the external data interconnect 2305 provides the data to the core prior to the write, while the external data interconnect is used after the core provides data for a read. In summary, a read uses resources in the order: (a) control interconnect 2304 , (b) column i/o 2307 , (c) data interconnect 2305 . A write uses them in the order: (a) control interconnect 2304 , (b) data interconnect 2305 , (c) column i/o 2307 . [0124] This change in resource ordering gives rise to resource conflict problems that produce data bubbles when mixing reads and writes. The resource ordering of writes generally leads to the resource timing shown in FIG. 17 . For example, a write uses resource as shown by block 2440 , the data resource as shown by block 2450 , and the column resource as shown by the block 2460 . This resource timing minimizes the control logic and the latency of writing data into the memory core. [0125] The read resource timing of FIG. 18 , illustrates a minimum latency read via block 2540 , column i/o block 2560 , and data block 2550 . When these timings are combined as shown in FIG. 19 , a data bubble is introduced between blocks 2652 and 2653 of FIG. 19 . This data bubble constitutes time during which the data pins are not being utilized to transfer data; the pins are inactive. Forcing the data pins to do nothing as a result of mixing reads and writes is a problem. [0126] Note that the data bubble appears regardless of whether the write 2642 and the read 2643 are directed to the same or different memory devices on the channel. Further note that the delay from the control resource to the column i/o resource is identical for reads and writes. In view of this, it is impossible for the data resource timing to be identical for reads and writes. [0127] Matching the timing of the write-use of the data resource to the read-use of the data resource avoids the problem stated above. Since the use of the data pins in a system environment has an intrinsic turnaround time for the external interconnect, the optimal delay for a write does not quite match the delay for a read. Instead, it should be the minimum read delay minus the minimum turnaround time. Since the turnaround delay grows as the read delay grows, there is no need to change the write control to data delay as a function of the memory device position on the channel. [0128] FIG. 20 shows an embodiment of the invention having delayed write circuitry. The column access control information on line 2706 is delayed for writes relative to when the column control information is presented to the core for reads. FIG. 20 shows multiplexor 2712 which selects between the write delay block 2709 and the normal column control output of the interface. The interface controls the multiplexor depending upon whether the transfer is a read or a write. However, there are many embodiments of this mechanism. For example, a state machine could introduce new delaying state transitions when the transfer is a write. [0129] FIG. 21 shows the operation of delaying the write to match the read in accordance with the present invention. In this figure, the delay from write control block 2842 to write data block 2852 is set to match the delay from read control 2843 block to read data 2853 block less the channel turnaround time. As long as different column data paths are used to perform the read column cycle and the write column cycle, the data bubble is reduced to the minimum required by channel turnaround requirements and is no longer a function of control or data resource conflicts. [0130] Since write latency is not an important metric for application performance, as long as the write occurs before the expiration of t RAS,MIN (so that it does not extend the time the row occupies the sense amplifiers, which reduces application performance), this configuration does not cause any loss in application performance, as long as the writes and reads are directed to separate column data paths. [0131] Delayed writes help optimize data bandwidth efficiency over a set of bidirectional data pins. One method adds delay between the control and write data packets so that the delay between them is the same or similar as that for read operations. Keeping this Apattern≅ the same or similar for reads and writes improves pipeline efficiency over a set of bidirectional data pins, but at the expense of added complexity in the interface. [0132] FIG. 22 shows that the offset between write data 2984 block and read data 2985 block has been reduced by 2 units of time, compared to the analogous situation of FIG. 15 . Split Control Resources [0133] FIG. 22 shows less than full utilization of the data interconnect due to the overloaded use of the command pins 2910 . The command pins can be partitioned so that these operations are delivered to the device in an independent fashion. The timing of such a control method is shown in FIG. 23 where the unified control has been partitioned into fields of control information, labeled primary field 3011 and secondary field 3012 . Generally speaking the primary control pins can be used to control the sense operation while the secondary control pins control read or write operations. An embodiment of the present invention allows full utilization of the data pins and can transfer minimum size data blocks back-to-back, for any mix of reads or unmasked writes, for any mix of hits, misses, or empty traffic, to or from any device, any bank, any row, and any column address with only bank conflict, channel turnaround at the write-read boundaries, and 2nd order effects such as refresh limiting the data channel utilization. With the addition of more interconnect resources the writes could be masked or unmasked. Observe that FIG. 23 presumes that the memory device is designed for an interconnect structure that has zero turnaround delay between writes and reads. [0134] FIG. 24 shows an embodiment of the invention that has separate control interconnect resources. In one embodiment it uses delayed writes. In another embodiment it can alternately specify either a masking or a precharge field, either singly or in conjunction with another field. In another embodiment it combines delayed writes and the masking versus precharge. In an alternative embodiment according to the present invention there are three methods for starting a precharge operation in the memory core: in the sense operation field on the primary control lines 3104 , as an alternative to the sense information; in the mask field on the secondary control lines, 3105 as an alternative to the mask information; and according to the device and bank addresses specified in a read or a write. [0138] The benefit of the present invention according to a specific embodiment is shown in Table 4 and FIG. 25 and FIG. 26 . Table 4 shows the specific logical pinout of the embodiment of FIG. 24 to be used for this illustrative purpose. TABLE 4 High Performance Logical Pin Description Name Count Description Reference Primary[2:0] 3 Primary request control 3104 Secondary[4:0] 5 Secondary request control 3105 DQA[8:0] 9 Low order data byte 3106 DQB[8:0] 9 High order data byte [0139] FIG. 25 and FIG. 26 show two alternative control packet formats for encoding, respectively, the sense and precharge operations on the primary control lines. Table 5 defines the fields in the alternative formats of the primary control packet. The PD field selects a specific memory device. A combined field carries both the bank and row address arguments of the sense operation, as previously defined. TABLE 5 Primary Control Packet Fields Field Description PD4T Device selector bit 4 True; for framing, device selection and broadcasting. PD4F Device selector bit 4 False; for framing, device selection and broadcasting. PD[3:0] Device selector, least significant bits. AV Activate row; also indicates format of packet. PA[16:0] Address; combining bank and row. PB[5:0] Bank address POP[10:0] Opcode of the primary control packet. [0140] FIG. 27 and FIG. 28 show two alternative control packet formats for encoding various operations on the secondary control lines. FIG. 27 shows the packet format when masking is not being performed while FIG. 28 shows the format when masking is being performed. Table 6 defines the fields in either format of the secondary control packet. Packet framing is accomplished via a framing bit. The M field is used to indicate which format of the packet is being presented as well as indicating whether write data being written to the core should be masked. The SO field indicates whether a read or write operation should be performed. Device selection for SO specified operations is accomplished according to the SD field which is compared against an internal register that specifies the device address. The SA field encodes the column address of a read or write operation. The SB field encodes the bank address of a read or write operation. If the SPC field indicates precharge, then the precharge operation uses the SD device and SB bank address. The SRC field is used for power management functions. The MA and MB fields provide a byte masking capability when the M field indicates masking. The XO, XD, and XB fields provide the capability to specify a precharge operation when the M field does not indicate masking. Note that, unlike the SPC field, this specification of a precharge has a fully independent device, XD, and bank address, XB, that is not related to the read or write operations. [0141] FIG. 29 shows the format of the data packet transmitted on the data wires. TABLE 6 Secondary Control Packet Fields Field Description SD[4:0] Device selector for Column Operation SS=1 Start bit; for framing M Mask bit, indicates if mask format is being used SO[1:0] Secondary Operation code SPC Precharge after possible Column Operation SRC Power management SA[6:0] Address for Column Operation SB[5:0] Bank for Column Operation MA[7:0] Byte mask for lower order bytes MB[7:0] Byte mask for higher order bytes XD[4:0] Device selector for Extra Operation XO[4:0] Extra Operation code XB[5:0] Bank for Extra Operation [0142] The operation of this embodiment can be most easily understood through various timing diagrams as shown in FIG. 30 through FIG. 45 . These figures can be divided into several series, each of which depicts different aspects of this embodiment's operation: FIG. 30 through FIG. 35 show a basic operation as an embodiment of the present invention, other operations can be thought of as compositions of these basic operations; FIG. 36 through FIG. 39 show compositions of the basic operations but distinct from notions of the universal sequence; FIG. 40 through FIG. 43 show operations according to the universal sequence, these figures demonstrate the ability of the embodiment to handle mixed read and write with mixed hit, miss, and empty traffic without control resource conflicts; and FIG. 44 through FIG. 45 show operations according to the universal sequence demonstrating less control conflicts than the prior art. Other control scheduling algorithms are possible which seek to minimize other metrics, such as service time, with or without compromising effective bandwidth. [0147] The nominal timings for the examples are shown in Table 7. TABLE 7 Nominal Timings Symbol Value (ns) t RP 20 t RAS, min 60 t RCD 20 t CAC 20 A description of each of the timing diagrams follows. [0148] FIG. 30 shows a timing diagram for a nominal read hit. Recall that a nominal hit reference means that the beginning and final state of the addressed bank is open and that the appropriate row is already in the sense amplifiers of the addressed bank. In this case no row operation is required. The secondary control packet specifies the read operation, device address, bank address, and column address. Some time later, the read data is driven on the data pins. In an embodiment according to the present invention it as a constant time, later fixed by the design of the memory device. [0149] FIG. 31 shows a timing diagram for a nominal read empty. Recall that a nominal empty reference means that the beginning and final state of the addressed bank is closed. In order to transfer data, the addressed bank is first sensed, and then, after t RCD , the read operation takes place just as for the read hit of FIG. 30 . Note that this particular example shows the precharge occurring using the primary control packet precharge mechanism. Alternately, other precharge mechanisms are used, since there are no other references contending for the control resources. [0150] FIG. 32 shows a timing diagram for a nominal read miss. Recall that a nominal miss reference means that the beginning and final state of the addressed bank is open, but that the row currently sensed in the bank is not the one addressed by the application reference. In this case, a precharge operation occurs, followed by a sense operation, and finally a read operation that causes the proper data to be driven out on the data pins. Any precharge mechanisms can be used. [0151] FIG. 33 shows a nominal write hit. The figure relates to a multistep write operation. Thus, there is a secondary control packet in order to get the transported data sent all the way into the memory core. This second secondary control packet provides a timing reference that indicates to the memory device that it is time to send the data to the core. [0152] FIG. 34 shows a timing diagram for a nominal write empty. A write empty operation is a combination of the actions needed for a read empty and a write hit. First, a sense operation is performed, followed by a write operation, including the secondary control packet, followed by some precharge operation, although a primary precharge operation is shown. [0153] FIG. 35 illustrates a timing diagram for a nominal write miss. Write miss operation is a combination of the actions needed for a read miss and a write hit. First, a precharge operation is invoked; a primary precharge operation is shown. A sense operation follows, along with the two secondary control packets needed to write the data all the way to the memory core. [0154] The previous figures show how various application references can be decomposed into the memory operations. FIG. 36 illustrates how one of these isolated references can be used for a sequence of memory references. In FIG. 36 a sequence of nominal read empty references is shown. In this case the XO precharge operation is used to perform the close operation at the end of the sequence. The present invention thus provides another precharge mechanism that neither overloads the external control pin resources, nor adds logic to the memory device. [0155] FIG. 37 shows timing for a series of nominal masked write empty references. In this case, the XO precharge operation is not available because those control pin resources are being used to supply the mask information. Instead, the SPC field is used in order to avoid bubbles, since the primary control pins are already committed to the series of sense operations. Presuming that the delay between sense and write operations is such that write read conflict problems are being avoided, as shown with the previous discussion on delayed writes, there is no real penalty for using the SPC field. This is different from reads, which would normally complete, and which desire to complete, sooner. This asymmetry between reads and writes leads to the cost reductions of the present invention by reducing required control bandwidth, while minimally impacting application performance. [0156] FIG. 38 shows a series of nominal masked write hit references. Note that although two secondary control packets were required to fully write data into the memory core for an isolated reference the average number needed is about one. [0157] FIG. 39 shows a timing diagram for a series of masked writes misses. In this example the SPC field is used to precharge the bank. Such a sequence is useful in a graphics application which varies the length of time it keeps any bank open depending upon the amount of rendering to be done. If more than one transfer is directed to the same row of the same bank of the same device then some of the SPC precharge operations and the corresponding sense operations can be removed. This is useful both to eliminate unnecessary (precharge, sense) power but also to reduce the effective number of independent banks required to sustain the effective bandwidth, even when bank conflicts might occur. [0158] FIG. 40 shows a timing diagram for the universal sequence for minimum size transfers when the write traffic is not masked. In this case the XO precharge operation can be consistently used for the precharge operation which begins the universal sequence, while the SPC field is used for the close operation which ends the universal sequence. As can be seen, once the first reference has completed its sequence every reference behind it continues without any delays due to control resource constraints. The only delays are due to external interconnect turnaround delays. The processor cache miss traffic typically does not contain frequent masked write activity but is latency sensitive. Since it does not use the masking capability it can use the XO precharge capability. [0159] FIG. 41 demonstrates the extra degree of freedom permitted when the transfer size per (sense, precharge) pair is twice the minimum transfer size. In this case some of the primary control bandwidth becomes available for precharge control. In this case the universal sequence can be implemented even for masked writes. [0160] FIG. 42 shows a timing diagram for the universal sequence for reads and unmasked writes when the transfer size is twice the minimum per (precharge, sense) pair. In this case the precharge step of the universal sequence is scheduled with the primary packet precharge while the close step is scheduled with the XO precharge. In this case not only is there adequate control bandwidth but there is more scheduling freedom for each of the steps of the universal sequence compared to the minimum transfer size per (precharge, sense) pair case. [0161] FIG. 43 shows a timing diagram for universal reads or masked writes or unmasked writes. In this case the precharge step of the universal sequence is still scheduled in the primary control packet but the close step is scheduled with the XO precharge operation. This reduces the scheduling flexibility compared to the unmasked case 24 but still permits full data pin utilization. [0162] The previous figures demonstrate the conditions in which the universal sequence can be scheduled. The ability to schedule the universal sequence guarantees that there will not be any control conflicts which reduce available data transfer bandwidth. However, none of the nominal reference sequences actually requires two precharges to be scheduled. So there is generally adequate control bandwidth for various mixes of miss and empty traffic as shown in FIG. 44 . [0163] FIG. 45 shows a timing diagram for another scheduling alternative when the transfer size is twice the minimum per (precharge, sense) pair and the traffic consists of all empty references. In this case both the sense and precharge can be scheduled on the primary control pins. [0164] FIG. 46 shows an alternative embodiment that includes all of the features of FIG. 24 , but includes additional capability to initialize, read and write registers, and supply power control information to the memory device. The pinout of this embodiment is summarized in Table 8. TABLE 8 Alternative High Performance Logical Pin Description Name Count Type Description FIG. 46 Reference CTM 2 RSL Transmit Clock 5301 CTMN (Clock To Master) CFM 2 RSL Receive Clock CFMN (Clock From Master) Primary[2:0] 3 RSL Primary request control 5305 Secondary[4:0] 5 RSL Secondary request control 5305 DQA[8:0] 9 RSL Low order data byte 5307 DQB[8:0] 9 RSL High order data byte SIO[1:0] 2 CMOS Bidirectional serial in/out for 5302 and 5304 device initialization, register ops, power mode control, and device reset. Used to form the SIO daisy chain. SCK 1 CMOS Serial clock for SIO and CMD 5303 pins. CMD 1 CMOS Command input used for 5302 power mode control, configuring SIO daisy chain, and framing SIO operations. [0165] FIG. 47 shows the operation sequence for the alternative embodiment of FIG. 46 . The refresh specific operations support a novel method of handling core refresh. These new core operations create the requirements for the Refresh and RefreshS operations coded in the primary control packet as shown in FIG. 46 . In addition, various power control operations are added to the primary control packet. [0166] FIG. 48 shows an embodiment of the physical construction in which not all of the pins of the memory device are connected to the bond pads of the die. These non-connected pins provide signal isolation and shielding, thus avoiding the expense of additional bond pads. For example, pin and internal conductor 5542 provides isolation for pin and internal conductors 5541 and 5543 . In one embodiment the non-connected pins are signal returns, such as ground, which are adjacent to the connected pins. [0167] According to an embodiment of the present invention the memory device of FIG. 46 has Auxiliary information 5302 transported in time according to FIG. 49 . Auxiliary information 5302 includes a field to specify an auxiliary operation, a control register address in the memory device, and data to be read or written from or to the control register. AuxClock is the AuxClock signal to the Auxiliary Transport Unit 5308 and is used to receive information from the auxiliary connections 5302 in FIG. 46 . Since Auxiliary Transport Unit 5308 operates to reset or initialize the memory device, the unit need only operate slowly. Accordingly, information is framed by the CMD signal, which can be a portion of the auxiliary connections 5302 , and received on the AuxIn signal as a serial bit stream. The format of the bit stream is shown in the tables below. As can be noted from Table 9 there are sixteen clock cycles during which a packet of information is received or obtained from the Auxiliary Transport Unit. The Aux information fields are the SOP[3:0] field and the SDEV[4:0] field for the SRQ packet. The SA packet has field SA[11:0], the SINT packet has a field of all zeros and the SD packet has SD[15:0]. In this embodiment of the present invention, the SRQ, SA, SINT and SD packets are received or obtained from the Auxiliary Transport unit in the order listed, unless only the SRQ packet is needed, in which case the other packets are not sent. The functions of each of the fields in the packets is tabulated in Table 10. TABLE 9 Control Register Packet Formats AuxClock SRQ packet SA packet SINT SD 0 rsrv rsrv 0 SD15 1 rsrv rsrv 0 SD14 2 rsrv rsrv 0 SD13 3 rsrv rsrv 0 SD12 4 rsrv SA11 0 SD11 5 rsrv SA10 0 SD10 6 SOP3 SA9 0 SD9 7 SOP2 SA8 0 SD8 8 SOP1 SA7 0 SD7 9 SOP0 SA6 0 SD6 10 SBC SA5 0 SD5 11 SDEV4 SA4 0 SD4 12 SDEV3 SA3 0 SD3 13 SDEV2 SA2 0 SD2 14 SDEV1 SA1 0 SD1 15 SDEV0 SA0 0 SD0 [0168] TABLE 10 Field Description for Control Register Packets Field Description rsrv Reserved SOP3..SOP0 Serial opcode. Specifies command for control register transaction. 0000 - SRD. Serial read of control register {SA11..SA0} of memory device {SDEV4..SDEV0}. 0001 - SWR. Serial write of control register {SA11..SA0} of memory device {SDEV4..SDEV0}. 0010 - SETR. Set Reset bit, all control registers assume their reset values. 0011 - CLRR. Clear Reset bit, all control registers retain their reset values. 0100 - SETF. Set fast (normal) clock mode for the clock circuitry SDEV4..SDEV0 Serial device field. SBC Serial broadcast. When set, memory device ignores {SDEV4..SDEV0} serial device field SA11..SA0 Serial address. Selects which control register of the selected memory device is read or written. SD15..SD0 Serial data. The 16 bits of data written to or read from the selected control register of the selected memory device. [0169] As is shown in Table 10, the memory device is selected by the SDEV field and the SOP field determines the Auxiliary Operation to be performed by the Register Operation Unit 5309 in FIG. 46 . The Auxiliary Transport Unit also supports the initialization of the memory device because the Auxiliary Transport Unit itself does not require initialization. This function is shown in FIG. 49 . In this diagram the CMD signal received by the Auxiliary Transport Unit has different framing information to indicate that an initialization packet follows. This causes all of the memory devices which are connected together on the same external connections in FIG. 46 to break apart a daisy chain connection formed from AuxIn through AuxOut to AuxIn of the next memory device in the chain as the initialization packet passes through the daisy chain. Next, the first memory device in the chain receives a device identification field from the Auxiliary Transport unit into one of its control registers. This field serves to identify the device for future Auxiliary Transport Operations. After the memory device has its control registers configured properly, the device field register is written again to change a bit, causing the first device in the chain to pass the Auxiliary information it receives to the next device in the chain. The sequence is repeated until all of the memory devices have their control registers properly configured and each device has an unique identification. [0170] According to an embodiment of the present invention the memory device of FIG. 46 receives power control information, specifying a change in the power mode of the memory device. While power control operations such as Powerdown and Nap are encoded into the precharge packets in one embodiment according to the present invention, other power control operations, such as ExitToNormal and ExitToDrowsy come in through the Auxiliary Transport Unit because the other units in FIG. 46 are not operational due to their reduced power state and because the Auxiliary Transport Unit operates relatively slowly compared to, for example, the Transfer Units, and so does not require much power while the other units are in their reduced power state. These Exit operations may be performed according to FIG. 50 . FIG. 50 shows a different framing by the CMD signal so that the Auxiliary Transport Unit can recognize the ExitToNormal or ExitToDrowsy request. According to the timing diagram, when a memory device receives a CMD signal 01 with 0 on the falling edge of AuxClock and 1 on the rising edge of AuxClock, the memory device will exit either the power down state or the nap state (Power State A in the timing diagram) and move to a new power state (Power State B in the diagram), depending on the state of the AuxIn Signal Line. If the AuxIn line is a 1, the memory device will exit to the normal state and if the AuxIn line is a 0 the memory device will exit to the drowsy state. In other embodiments, the meaning of the AuxIn bits is reversed. The device that is targeted for the ExitToNormal or ExitToDrowsy operation is received by the Auxiliary Transport Unit 5308 on the data input field via path 5307 of the memory device in FIG. 46 . [0171] In an alternate embodiment, each memory device receives a different CMD signal, one for each device, rather than using the data input field via path 5307 to identify the device for a ExitToNormal or ExitToDrowsy operation. [0172] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. In other instances, well known circuits and devices are shown in block diagram form in order to avoid unnecessary distraction from the underlying invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

An integrated circuit memory device includes a memory core to store write data, a first set of interconnect resources to receive the write data, and a second set of interconnect resources to receive a write command associated with the write data. Information indicating whether mask information is included with the write command, wherein the mask information, when included in the write command, specifies whether to selectively write portions of the write data to the memory core.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from U.S. Provisional Patent Application Ser. No. 61/346,976, filed May 21, 2010. FIELD OF THE INVENTION The present invention relates to the art of orthopedic cutting tools, and more particularly, to a disposable cutter used for shaping and preparing the femoral bone for implant insertion. PRIOR ART Cutting tools used in orthopedic procedures are designed to cut bone and associated tissue matter. Specifically, cutters of the present invention are designed to cut and shape the end of a long bone such as a femur or humerus. Typically, the end of the long bone is cut and shaped for insertion of an implant. As such, these cutters are required to be sterile and sharp. Using a dull cutter generates heat that typically leads to tissue necrosis and results in undesireable patient outcomes. A non-sterile cutter blade typically results in an infected and damaged bone that may lead to other problems for the patient. Depicted in FIGS. 1 and 1A are images of a prior art bone cutter 10 designed to cut and shape the femoral head 12 of the femur 14 . As shown in the figures, the prior art cutter 10 is similar to that of a “hole saw” drill. These prior devices 10 generally comprise a hollow cylinder in which a series of cutting teeth slots 16 are formed within the cylinder wall thickness 18 . However, these prior devices 10 do not remove all the bone 14 required to properly fit an implant. Therefore, additional procedures are required to remove this extra bone material 22 and smooth the surface of the bone end 24 . As shown in FIG. 1A , the prior cutter device 10 imparts a channel 20 within the end 24 of the bone 14 . This channel 20 and associated bone material 22 proximate the channel 20 , must be removed to properly fit the implant (not shown) on the end 24 of the bone 14 . Typically, hand tools such as rongeurs are used to remove this extra bone material 22 . Such a bone removal procedure makes it difficult to properly fit an implant over the end 24 of the bone 14 . The extra bone material 22 must be intricately removed to produce a smooth surface and ensure that the bone 14 is shaped to meet the exacting dimensions of the implant. If the implant is not properly fit over the end 24 of the bone 14 , undesirable implant wear or improper implant operation could result. In addition to the inefficient bone removal limitations, traditional bone cutters are typically reused multiple times. That is because of their high cost. Such multiple reuses require that the cutter be cleaned and sterilized before each use. Furthermore, over time, as these cutters are used and reused, they become dull, thus requiring resharpening. Therefore the blades of the cutter are required to be resharpened, cleaned and sterilized. However, these resharpening and sterilization processes add additional costs and increase the possibility of infection. In addition, resharpening tends to deform the dimensions of the cutter. These dimensional changes could adversly impact the optimal fit and function of the implant. Furthermore, there is a high likelihood that the cleaning and sterilization process may not remove all possible infection agents such as bacteria, machining lubricants, and the like. Accordingly, the present invention provides a cost effective single use bone cutter with a novel blade and assembly design that improves cutting efficiency. The enhanced bone cutting and shaping efficiencies of the present invention ensure proper implant fit and reduced implant wear. In addition, the improved bone cutting efficiencies afforded by the present invention, decrease procedural time and minimize patient trauma. Furthermore, the bone cutter of the present invention ensures proper cutter sharpness and cleanliness that promotes optimal patient outcomes. SUMMARY OF THE INVENTION The present invention provides a disposable bone cutter device comprising a cutter assembly and guide rod for orthopedic surgical applications. Specifically, the cutter device of the present invention is designed to re-shape the head of a femur for joint revision surgeries. The cutter assembly comprises a disposable housing and a series of insert blades or a cutter disc arranged in circumferential manner within the assembly. The series of insert blades or cutter disc are preferably secured in the cutter assembly through an interference fit at a distal base portion of the cutter assembly. The housing comprises two cylinders that are joined together at a distal portion of the housing. In a preferred embodiment, a first cylinder is positioned such that its inner diameter circumferentially surrounds the outer diameter of a second cylinder. Both the first and second cylinders are positioned such that they share a common central longitudinal axis. A series of radial connectors join the two cylinders together along the distal base portion of the assembly. In a preferred embodiment, these connectors may take the form of a bar or rod or alternatively be formed into a blade enclosure designed to secure and house the individual insert cutter blades. Furthermore, it is preferred that the distal base portion of the centrally located second cylinder is recessed or offset from the distal base of the first cylinder. This recess establishes an offset rim formed by the wall thickness of the first cylinder. The depth of the offset rim is determined by the gap between the distal base plane of the first cylilnder and the distal base plane of the second cylinder. The offset rim provides a barrier that prevents unintentional damage to nearby bone and/or tissue resulting from contact with the cutting surface of the insert blades or cutting disc. Located at the proximal end portion of the assembly, within the interior of the inner diameter of the centrally located second cylinder, is a boss. The boss comprises a central throughbore that is positioned such that the throughbore is coaxial with the common longitudinal axis. The throughbore of the boss provides an alignment aid to the axis of the desired cut. Another feature of the boss is that it acts as a “stop” to prevent overcutting of the bone. As will be explained in greater detail, the distal end of the boss comes into contact with the end of the bone thus preventing further advancement of the cutter. As such, the position of the boss preferably determines the depth of cut into the bone and prevents unintentional overcutting of the end of the bone. The boss is joined within the interior of the second cylinder through a series of rods which radially extend between the exterior wall surface of the boss and an interior wall surface of the inner diameter of the second cylinder. In addition, these rods serve as an interfacing feature by which the cylindrical cutter attaches to a handle or a motor that rotates the cutter in a clockwide or counterclockwise direction. In a preferred embodiment, the housing can be produced as a single component using an injection molding process. The insert blades are universal and can be manufactured to a minimal size to accommodate all sizes of the cutter. In a preferred embodiment, the series of individual cutter blades are secured within their respective blade enclosures. These blades are preferably of an “L” shape and are designed to provide a cutting edge that extends into the interior of the centrally located second cylinder. The cutter insert blades preferrably include a slot, residing within the surface that extends along the width of the blade. The slot is designed to interface with a post positioned within the blade enclosure. The interaction between the post and slot secures the insert blade therewithin. In this embodiment, the cylindrical cutter is assembled by pressing the insert blades into the blade enclosures of the assembly. The insert blades are designed such that they snap into the blade enclosure. This low cost production process, along with the economical production of the component parts, avoids the need for expensive machining and grinding operations that are common with the prior art. In an alternate embodiment, a cutter disc having a plurality of cutting teeth openings, resides within the distal base portion of the assembly. In a preferred embodiment, the cutting disc comprises an outer diameter, an inner diameter, and a planar surface therebetween. The plurality of cutting teeth are positioned at spaced intervals throughout the planar surface. In operation, the femoral head is first shaped to accept a replacement shell of an implant utilizing the present invention. The shaping of the femoral head is accomplished by first establishing an axis of cut on the femoral head. This axis is established by drilling a guide hole into the femoral head and placing a guide rod into the bone. This guide rod serves to align the axis of the cylindrical cutter to the axis of the intended cut. The cutter of the present invention is then attached to the handle-driver assembly and positioned over the guide rod by means of the hollow boss within the cylindrical cutter. The powered driver provides a means of rotating the cylindrical cutter and advancing the cutter against the femoral head. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a prior art bone cutter and bone. FIG. 1A is a cross-sectional view of the prior art bone cutter and bone shown in FIG. 1 . FIG. 2 is a perspective view of the cutter housing of the present invention. FIG. 3 is an alternate perspective view of the cutter housing of the present invention. FIG. 4 is a cross-sectional view of the cutter housing of the present invention. FIG. 5 is a perspective view of an embodiment of a cutter blade of the present invention. FIG. 6 is a side view of the embodiment of the cutter blade shown in FIG. 5 . FIG. 7 is a perspective view of an alternate embodiment of a cutter blade of the present invention. FIG. 8 is a perspective view illustrating an assembly step of the present invention. FIG. 8A is a perspective view illustrating a preferred embodiment of an assembled bone cutter assembly of the present invention. FIG. 9 is a perspective view of a preferred embodiment of a cutter disc of the present invention. FIG. 10 is a perspective view of the cutter disc and an alternative cutter housing embodiment of the present invention. FIG. 10A is a perspective view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in FIG. 10 . FIG. 10B is a cross-sectional view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in FIG. 10 . FIG. 11 is a cross-sectional view of an embodiment of the bone cutter of the present invention being used to shape the end of a bone. FIG. 11A is a cross-sectional view illustrating the shaped end of a bone after using the bone cutter of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now turning to the figures, FIGS. 2-11A illustrate embodiments of a bone cutter 30 of the present invention. In a preferred embodiment, the bone cutter 30 comprises a cutter housing 32 , cutter blades 34 or cutter disc 78 , and a guide rod 36 ( FIGS. 11 , 11 A). As shown in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A, the cutter housing 32 preferably comprises two cylinders, a first cylinder 38 and a second cylinder 40 that are joined therebetween. In a preferred embodiment, the first cylinder 38 comprises a first cylinder inner diameter 42 , a first cylinder outer diameter 44 , and a first cylinder wall thickness 46 therebetween. The second cylinder 40 comprises a second cylinder inner diameter 48 , a second cylinder outer diameter 50 , and a second cylinder wall thickness 52 therebetween. In addition, the first cylinder 38 comprises a first cylinder height 54 extending from a first cylinder distal base portion 56 to a first cylinder proximal end portion 58 . In a preferred embodiment, the distal base portion 56 of the first cylinder 38 is co-planar with an imaginary first cylinder base plane B-B ( FIG. 4 ). This imaginary base plane B-B preferably extends outwardly from the outer diameter 44 of the first cylinder base portion 56 . The second cylinder 40 comprises a second cylinder height 60 extending from a second cylinder distal base portion 62 to a second cylinder proximal end portion 64 . In a preferred embodiment, the distal base portion. 62 of the second cylinder 40 is co-planar with an imaginary second cylinder base plane C-C ( FIG. 4 ). This imaginary base plane C-C preferably extends outwardly from the outer diameter 50 of the second cylinder base portion 62 . In a preferred embodiment, the first and second cylinders 38 , 40 are joined such that the outer diameter 50 of the second cylinder 40 is positioned within the inner diameter 42 of the first cylinder 38 . The first and second cylinders 38 , 40 are further positioned such that they are co-axial to a common central longitudinal axis A-A as shown in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A. In a preferred embodiment, the outer diameter 44 of the first cylinder 38 ranges from about 5 cm to about 10 cm, the inner diameter 42 of the first cylinder 38 ranges from about 4.5 cm to about 9.95 cm and the height 54 of the first cylinder 38 ranges from about 1 cm to about 4 cm. The wall thickness 46 of the first cylinder 38 preferably ranges from about 0.05 cm to about 0.5 cm. In a preferred embodiment, illustrated in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A, the height 60 of the centrally located second cylinder 40 is greater than that of the height 54 of the first cylinder 38 . Furthermore, the height 60 of the centrally located second cylinder 40 ranges from about 5 cm to about 10 cm. The outer diameter 50 of the second cylinder 40 ranges from about 3 cm to about 6 cm and the inner diameter 48 of the second cylinder 40 ranges from about 2 cm to about 6 cm. The wall thickness 52 of the second cylinder 40 ranges from about 0.05 cm to about 0.5 cm. The two cylinders 38 , 40 are joined together by a connector 66 that interfaces between the two cylinders 38 , 40 at a distal end portion 67 of the housing 32 as shown in FIG. 10 . The connector 66 can be of many non-limiting forms such as a bar, a rod, a rectangle or a sphere such that one surface interfaces with the interior wall surface 68 of the inner diameter 42 of the first cylinder 38 and an opposite surface interfaces with the exterior wall surface 70 of the outer diameter 50 of the second cylinder 40 . In a preferred embodiment, a plurality of two or more connectors 66 , radially extend between the inner and outer diameters 42 , 50 of the first and second cylinders 38 , 40 , respectively, and join them therebetween as shown in FIG. 10 . In a preferred embodiment, the connector 66 can be designed as a blade enclosure 72 such that individual insert blades 34 ( FIGS. 2-3 , and 8 - 8 A) are disposed therewithin. This preferred blade enclosure 72 embodiment, will be discussed in more detail. As shown in the embodiments illustrated in FIGS. 3-4 , 8 - 8 A, and 10 - 10 A, the housing 32 is preferably constructed such that an offset rim 74 is formed by a portion of the wall thickness 46 of the first cylinder 38 . The depth 76 of the offset rim 74 is defined by the distance between the first and second imaginary distal base planes B-B, C-C as shown in the cross sectional view of FIG. 4 . In a preferred embodiment, the offset rim 74 preferably has a depth 76 that ranges from about 0.01 cm to about 0.05 cm. The offset rim 74 preferably extends around the perimeter of the first cylinder 38 at the distal base portion 56 . The thickness of the offset rim 74 is defined by the wall thickness 46 of the outer first cylinder 38 . The offset rim 74 is designed to prevent the cutter blades 34 or cutter disc 78 ( FIG. 9 ) from inadvertently damaging nearby bone or tissue, particularly preventing a proximal bone or tissue from being cut or nicked. However, it is contemplated that the housing 32 could be constructed such that the first and second imaginary planes B-B, C-C are coplanar, therefore constructing a housing 32 without an offset rim 74 . It is preferred that both the first and second cylinders 38 , 40 have a hollow interior 80 , 82 within their respective inner diameters 42 , 48 . Such a hollow interior 80 , 82 allows for efficient removal of bone debris as the debris can freely flow through the cutter assembly 84 ( FIGS. 8 , 8 A). It is also contemplated that such a housing 32 , could be constructed with a cylinder having a solid or partially solid interior. In a preferred embodiment shown in FIGS. 2 , 4 , 8 A, and 11 - 11 A, the cutter housing 32 has a boss 86 that is positioned within the inner diameter 48 of the second cylinder 40 . More specifically, the boss 86 is centrally positioned within the inner diameter 48 of the second cylinder 40 . In a preferred embodiment, the boss 86 comprises a throughbore 88 . The boss 86 is preferably further positioned within the inner diameter 48 of the second cylinder 40 such that the throughbore 88 is co-axially aligned with the central axis A-A of the housing 32 as shown in FIGS. 2 , 4 , 8 A, and 11 - 11 A. In a preferred embodiment, illustrated in FIG. 4 , the boss 86 is constructed with a distal planar edge 90 . This distal planar edge 90 is designed to act as a “stop” to prevent further advancement of the cutter 30 into the end 24 of the bone 14 . The boss 86 is preferably positioned with the interior 82 of the second cylinder 40 such that a cut depth 92 is defined between the distal planar edge 90 of the boss 86 and the imaginary second cylinder base plane C-C. It is contemplated that this distal planar edge 90 can be positioned anywhere within the interior 82 of the centrally located second cylinder 40 to establish an optimal cut depth 92 for a particular implant (not shown). In a preferred embodiment the cut depth 92 ranges from about 2 cm to about 10 cm. A plurality of bars 94 secure the boss 86 within the inner diameter 48 of the centrally located second cylinder 40 . A plurality of bars 94 , having a length 96 from about 4 cm to about 8 cm and a thickness 98 from about 0.5 cm to about 1 cm, fluidly extend from the interior wall surface 68 of the inner diameter 48 of the first cylinder 38 to the exterior wall surface 70 of the outer diameter 50 of the second cylinder 40 within the proximal portion 64 of the housing 32 . It is preferred that a plurality of at least two bars 94 , connect the boss 86 within the interior 82 of the second cylinder 40 . It is preferred that the housing 32 be composed of a biocompatible material. In a preferred embodiment, the cutter housing 32 is composed of a biocompatible thermoplastic such as, but not limited to, Acrylonitrile Butadiene Styrene (ABS), Polyarylamide (PAA), or Polyetheretherketone (PEEK). Furthermore it is preferred that the series of cutter blades 34 are positioned in a radial fashion about the outer diameter 50 of the second cylinder 40 as illustrated in FIGS. 8 and 8A . More specifically, these cutter insert blades 34 are positioned between the exterior surface 70 of the outer diameter 50 of the second cylinder 40 and the interior surface 68 of the inner diameter 42 of the first cylinder 38 at the distal base portion 56 of the housing 32 . Preferred embodiments of the cutter insert blade 34 , 130 are shown in FIGS. 5-7 . As illustrated, insert blades 34 , 130 comprise a blade proximal portion 100 and a blade distal portion 102 . The widths 104 , 106 of the proximal and distal portions 100 , 102 are not necessarily equal. In a preferred embodiment, the width 106 of the distal portion 102 is greater than the width 104 of the proximal portion 100 . An insert blade cutting surface 108 preferably extends along the distal width 106 of the insert blade 34 , 130 . In a preferred embodiment, when inserted into the bone cutter housing 32 , the plurality of these blade cutting surfaces 108 align to form an imaginary blade cutting surface plane D-D ( FIG. 4 ). It is further preferred that this imaginary blade cutting surface plane D-D reside between the imaginary first and second cylinder planes B-B, C-C. As shown in FIGS. 5 , 7 and 8 A, the distal width 106 of the insert blade 34 , 130 is greater than the proximal width 104 of the blade 34 , 130 . This extra “width portion” of the insert cutter blade 34 , 130 is defined as the blade extension portion 110 . The blade extension portion 110 is designed such that when the cutter blade 34 , 130 is inserted into the housing 32 , the extension portion 110 protrudes past the inner diameter 48 of the second cylinder 40 towards the interior 82 of the second cylinder 40 . In addition, the blade extension portion 110 acts as a “free end”. This “free end” extension is designed to cut into the head 12 of the bone 14 . As such, this “free end” extension 110 defines a new diameter 112 of the bone head 12 as illustrated in FIG. 11A . If such an extension 110 were not present, the interior wall 69 of the second cylinder 40 would prevent cutting of the bone 14 . In a preferred embodiment, the blade extension 110 has a width from about 0.05 cm to about 0.10 cm. As illustrated in FIGS. 5 and 6 , a groove 114 is preferably formed within the surface 116 of the distal end portion 102 of the insert blade 34 . In a preferred embodiment, the groove 114 has a “V” shape. The groove 114 is designed to establish a rake angle θ of the insert blade 34 . The rake angle θ is defined as the intersection between the distal surface 120 of the “V” cut out portion 114 and a perpendicular line E-E to the cutting edge surface 108 as shown in FIG. 6 . It is preferred that rake angle θ range from about 4° to about 30°. A relief angle Ø, as illustrated in FIG. 6 , is formed between the intersection of the distal end surface 124 of the blade 34 and a tangent line F-F to the blade cutting edge 108 . It is preferred that the relief angle Ø range from about 4° to about 20°. Each cutter blade 34 , 130 is preferably positioned within the cutter blade enclosure 72 as shown in FIGS. 8 and 8A . In a preferred embodiment, the insert blade 34 , 130 is positioned in the housing 32 such that the proximal end portion 104 of the insert blade 34 , 130 resides inside the blade enclosure 72 and the cutting surface 108 of the insert blade 34 , 130 lies outside the blade enclosure 72 . Furthermore, it is preferred that the cutting surface 108 of the insert blade 34 lies parallel to an imaginary cutting plane D-D as shown in FIG. 4 . As shown in FIG. 4 , the imaginary cutting plane D-D lies between the first cylinder imaginary plane B-B and the second cylinder imaginary plane C-C. The blade extension 110 preferably is positioned towards the central axis A-A of the assembly 84 . In a preferred embodiment shown in FIGS. 2 and 3 , each cutter blade enclosure 72 has a post 126 therewithin. The post 126 is preferably designed to snap-fit into a slot 128 within the proximal end portion 100 of the cutter blade 34 ( FIGS. 5 and 6 ). Once the post 126 snaps into the slot 128 , the insert blade 34 is locked within the cutter blade enclosure 72 . In an alternative embodiment, as shown in FIG. 7 , the insert blade 130 can be designed without a groove 114 and slot 128 . In this embodiment, the cutting edge 108 is formed at the intersection of the side blade surface 116 and the distal end surface 124 . It is preferred that a portion of the surface 116 at the proximal end portion 100 of the insert blade 130 has a roughened finish 132 . This roughened surface finish portion 132 provides for a more secure fit when positioned within the blade enclosure 72 . In a preferred embodiment, insert blades 34 , 130 are secured within the blade enclosure 72 with an induction bonding process. Alternatively, the insert blade 34 , 130 can be secured by an alternate means not limited to adhesives, overmolding, press fitting, induction bonding, and the like. In an alternate embodiment, the cutting disc 78 is positioned at the distal end portion 67 of the housing 32 . The cutting disc 78 embodiment provides an additional means of bone removal which is illustrated in FIGS. 9-10A . An embodiment of this alternate cutter assembly 146 is shown in FIG. 10A . The assembly 146 of this embodiment comprises the housing 32 and the cutter disc 78 . The cutting disc 78 preferably comprises an outer disc diameter 134 , an inner disc diameter 136 and a planar surface 138 therebetween. The cutting disc 78 is positioned between the wall thickness 46 of the first cylinder 38 and the wall thickness 52 of the second cylinder 40 at the distal end portion 67 . More specifically, it is preferred that the cutting disc 78 be placed between the inner diameter 42 of the first cylinder 38 and the inner diameter 48 of the second cylinder 40 such that the planar surface 138 of the cutting disc 78 is parallel to the first and second cylinder imaginary planes B-B, C-C ( FIG. 10B ). Positioned throughout the surface 138 of the disc 78 are a series of openings 140 . These openings 140 are preferably positioned throughout the surface 138 of the disc 78 in a helical pattern. Protruding from the opening 140 is a cutting tooth 142 . The cutting teeth 142 are designed such that a cutting surface 144 is positioned outwardly from the planar surface 138 of the disc 78 . Alternately, the cutting surface 144 may protrude inwardly from the surface 138 of the disc 78 . In a preferred embodiment, these cutting surfaces 144 of the cutting teeth 142 align to form an imaginary cutting disc plane G-G. This imaginary plane G-G preferably resides between the first and second imaginary cylinder planes B-B, C-C ( FIG. 10B ). It is preferred that the cutter insert blades 34 , 130 and the cutting disc 78 are composed of a biocompatible metal. In a preferred embodiment, such biocompatible metals include, but are not limited to, stainless steel, MP35N, titanium, and combinations thereof. It is most preferred that cutter blades 34 , 130 and the cutting disc 78 are composed of a 300 series stainless steel. In a preferred embodiment, the cutter housing 32 is first molded from a biocompatible polymer as previously mentioned. After the housing 32 has been molded, the cutter blades 34 , 130 or cutter disc 78 are then inserted in the distal base portion 67 of the housing 32 . As previously mentioned, an induction bonding process is preferably used to secure the cutter blades 34 , 130 or cutter disc 78 to the molded assembly 84 , 146 . Alternatively, adhesives, overmolding, press fitting, and the like may also be used. In this preferred bonding embodiment, electromagnetic current is used to heat the blades 34 , 130 or blade disc 78 . Heat generated from the current, melts the surrounding assembly polymer material, causing the material to flow and engage the cutter blades 34 , 130 or disc 78 . It is well known that alternative processes such as cross pinned engagements, direct insert molding, or ultrasonic insertion may also be used to strengthen the connection or act as a primary means to join the bone cutter 30 of the present invention. FIGS. 11 and 11A illustrate the use of the bone cutter 30 of the present invention. Initially, a guide-hole 148 is drilled into the end 24 of a bone 14 . The guide rod 36 is placed into the guide-hole 148 and the cutter assembly 84 , 146 is placed over the rod 36 as shown. In a preferred embodiment, the guide rod 36 is preferably positioned through the central axis A-A of the bone cutter 30 . Once in place over the end 24 of the bone 14 , the cutter 30 is rotated in either a clockwise or counterclockwise direction. This rotational movement of the cutter 30 , removes bone material from the end 24 of the bone 14 with a smooth surface finish with a bone diameter 112 suitably sized for insertion of an implant (not shown). Once the bone head 12 is properly shaped, the cutter 30 and guide rod 36 are removed. An implant (not shown) is then positioned over the end 24 of the bone 14 . Now, it is therefore apparent that the present invention has many features and benefits among which are promoting proper implant fit, decreased procedural times and minimized patient trauma. While embodiments of the present invention have been described in detail, that is for the purpose of illustration, not limitation.

A single use bone cutter comprised of two concentric cylinders and a series of insert blades or cutter disc is described. The cutter blades or cutter disc is preferably positioned at the distal end of the cutter. The bone cutter also comprises a guide rod that aids in the line of sight when using the cutter device.

FIELD OF THE INVENTION The present invention relates to a rotary device for mounting at intersections of a transport rail system comprising transport units. It serves for guiding the transport units to the transport rails running in any direction and for simultaneously ensuring the supply of power and of control signals to the transport units. Mounted on the transport units are, for example, lamps which are supplied with energy and possibly control signals by the transport units and thus ensure flexible and, if required, even mobile illumination of a room, for example a television studio. DESCRIPTION OF THE PRIOR ART Conventional lighting systems for television studios, theater stages or the like have, for example, spotlights which are mounted on a transport rail system present on the ceiling and comprising turntables and can be manually positioned on the rails. Supply boxes from which a positioned spotlight can be supplied with power and control signals are mounted at regular intervals on the ceiling. However, such an arrangement requires relatively early and manual preparation for the event for which the lighting system is to be used and makes flexible, short-term adaptation of the lighting situation more difficult. Another system for a lighting system envisages mounting a large number of spotlights which are adjustable only in height, it being possible, depending on requirements, to use those spotlights which are located in the suitable place. Only the height of the spotlights can be freely chosen. Although this system permits flexible work, it requires large investments in expensive spotlight systems and considerably limits the number of systems from which a spotlight can be used. Yet another system is based on a transport rail system which can be installed in the ceiling structure of a studio. Thus, a transport rail system has rails which are parallel to one another and run over the entire length of the region in which spotlights are to be used. In each case a plurality of rail sections whose direction of travel is perpendicular to the direction of travel of the rails are mounted displaceably on a pair of such rails. The spotlights are fastened to transport units which can be pushed onto the rail sections. Two rail sections on adjacent pairs of rails can then be brought into position so that they are flush with one another and a transport unit of a spotlight can be moved from one rail section to the next. In this way, a spotlight can in principle be brought to any desired position on the ceiling. however, such a system has the substantial disadvantage that the transport distances on the rail system are long and inconvenient if the lighting system has a relatively large number of spotlights which possibly also are of various design and perform various functions, since rail sections occupied by transport units hinder one another during changes of position. SUMMARY OF THE INVENTION It is the object of the present invention to permit a lighting system which does not have the disadvantages of the systems described above and in which the lamps can be flexibly moved even while they are in use. The invention relates to a rotary device, namely a rotary device for mounting at intersections between stationary transport rails which are provided with contact tracks and form part of a transport rail system for conveying transport units, the rotary device having two components which are rotatable relative to one another and of which one is in the form of a pivot bearing for the other, which rotary bearing serves for fastening at the intersection, while the other is a rail support containing at least one rail section. In the device according to the invention, each rail section of the rail support is provided with contact tracks so that a transport unit present on the rail section and having a current collector can obtain energy. Furthermore, the invention also relates to a lighting system comprising lamps for illuminating television studios, theater or concert stages or the like, wherein the lamps are provided with transport units which can be positioned on a transport rail system comprising transport rails having contact tracks, these transport units having current collectors which make contact with the contact tracks, and wherein one rotary device as described above is present at each of the intersections of this transport rail system. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is explained below with reference to a drawing. In the drawing, FIG. 1 shows a perspective view of a rotary device according to the invention, FIG. 2 shows a perspective view of the pivot bearing of this device, FIG. 3 shows a view, also a perspective one, of its rail support, FIG. 4 shows a longitudinal section through the rail section of the rail support with mounted trolley shown uncut and FIG. 5 shows a perspective view of a part of a lighting system which is provided with rotary devices according to the invention, with a lamp shown schematically. DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the rotary device consists of two components, of which one in the form of a pivot bearing, denoted as a whole by 1 and to be installed firmly at intersections of the transport rail system, for the other, denoted as a whole by two, and referred to below as rail support. The pivot bearing 1 essentially comprises a hollow cylinder 11 having an external diameter D a and an internal diameter D i . This is provided with threaded holes 12 which can be engaged by fastening means in order to fasten the rotary device to a ceiling or to a scaffolding. Depending on the structure of the transport rail system, for example, eight rail attachments 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 of stationary transport rails are fixed to the cylinder 11 and are led radially outward from the cylinder surface, in each case two adjacent attachments making an angle of 45° with one another. The rail support 2 likewise essentially comprises a hollow cylinder 50 whose external diameter d a is slightly less than the internal diameter D i of the hollow cylinder 11 belonging to the pivot bearing 1 . It is additionally provided at the top with a flange 51 having an external diameter d f which is at least equal to D a . Mounted in the lower part of the rail support is a rail section 52 which runs along a diagonal of the cylinder 50 . Each of the rail attachments 21 to 28 as well as the rail section 52 are symmetrical with respect to a plane which runs along the rail direction and is vertical in the example shown. Each rail attachment 21 to 28 or each rail section 52 has a ceiling 31 , two side walls 32 , 33 and two runways 34 , 35 . A transport unit 70 in the form of a trolley is displaceable on the runways 34 , 35 , along the direction of travel of the rail. A plastics band 36 is mounted on each of the two side walls 32 , 33 of the rails. Each of the plastics bands is provided with at least two grooves, each of which contains a current-carrying rail 37 or 38 which is opened toward the inside of the rail and serves as a contact track. Those contact tracks 37 , 38 of the rail attachments 21 to 28 which are opposite one another make contact with one another via connections 46 , 47 . The connections 46 , 47 can be, for example, in the form of current-carrying cables mounted on the outside of the rail attachments 21 to 28 , which cables make contact with the contact tracks 37 , 38 through orifices in the side walls 32 , 33 . Also mounted in the interior of the hollow cylinder 11 of the pivot bearing 1 of the rotary device is a plastics band 41 with inserted current-carrying rails 42 , 43 which are connected directly to the current-carrying rails 37 , 38 of the rail attachments 21 to 28 . The rail support 2 has contact pins 44 , 45 which are connected to the contact tracks 37 , 38 of the rail section 52 and, in the state ready for operation, are pressed, for example by a spring, against the current-carrying rails 42 , 43 so that they make electrical contact with them. The trolley 70 shown schematically in FIG. 4 has a plurality of axles with wheels 71 running on the runways 34 , 35 , and drive means by which it can be moved along the rail. Current collectors 72 which slide along the contact tracks 37 , 38 are mounted on that side of the trolley 70 which faces the observer in FIG. 4 . In the embodiment shown in FIG. 2, the trolley 70 has one set of current collectors each at the front and rear in the direction of travel, only two current collectors 72 being present per set, corresponding to the number of contact tracks 37 , 38 . However, the number of current collectors does of course increase with the number of contact tracks 37 , 38 , if more than two of these are present. In addition, the trolley also has wheels 73 which are mounted at its top and, by running on the ceiling 31 , prevent the trolley 70 from rearing up at large accelerations and the current collectors from losing contact with the current-carrying rails 37 , 38 . In the state ready for operation, the rail support 2 , as shown in FIG. 1, is inserted into the pivot bearing 1 of the rotary device. Present between the flange 51 and the upper edge 11 a of the cylinder 11 is a roller bearing 61 which makes it possible for the rail support 2 to be turned with little resistance against the pivot bearing 1 . For this purpose, the rail support 2 has an actuator. An electric motor 63 connected via supply cables 62 to the current-carrying rails 37 , 38 of the rail section 52 is fastened to the inside of the rail support 2 . If required, said motor produces a rotation of the rail support via a plastics gear wheel 64 which engages, through an orifice 65 in the cylinder 50 , the teeth of a plastics toothed rack 66 countersunk in the inner surface of the cylinder 11 . In addition, spherical indentations 67 are provided at predetermined positions at an angular spacing of 45° relative to one another on the inside of the hollow cylinder. A ball 68 is mounted on the outside of the cylinder 50 and is pressed outward by a spring against a stop or, in the state ready for operation, against the inside of the cylinder 11 . It then snaps into one of these indentations when the rail support is aligned in such a way that one of the rail attachments 21 to 28 is in the direction which leads radially outward from its rail section 52 . In this way, the positions in which a transport unit can be moved onto the rail support 2 or away from it are defined as fixed positions of the rail support 2 . The structure and the mode of operation of a lighting system provided with rotary devices according to the invention are described briefly below. FIG. 5 shows a view of a part of such a lighting system comprising a lamp 80 shown only schematically. The lamp 80 is, for example, a spotlight having a set of color filters and a device for inserting a filter from this set. As is known for traditional lighting systems, it is provided with means by which its height can be adjusted and by which its light can be thrown in any desired direction. The spotlights, together with the device for inserting the color filters, are supplied with power via the contact tracks and via the trolley 70 . For feeding current and, depending on requirements, control signals into the contact tracks 37 , 38 , 42 , 43 of the transport rail system, one of the rails installed in a fixed position is in contact with cables which are connected to a power unit and, if required, control devices. The contact tracks 42 , 43 of the pivot bearing 1 , together with the connections 46 , 47 , which connect together the opposite contact tracks 37 , 38 of the stationary rails, and with the connections to the rail sections 52 of the rail support 2 via the contact pins 44 , 45 , ensure that the entire rail network is continuously connected to power units and control devices, subdivision into sectors which in each case have a separate power supply also being possible in the case of relatively large lighting systems. In this case, the trolley of each transport unit, as shown in FIG. 4, has two sets of current collectors one behind the other in the direction of travel and a relay circuit which switches back and forth between the two current collector sets to prevent a trolley from short-circuiting two sectors with one another. The lighting system also has a central control unit not shown in the drawing. With the aid of this control unit, the position and current function of each spotlight can be continuously adapted to the requirements according to a predetermined program or by direct operation. The actuation of the spotlights, of the devices for inserting the color filters, of the trolleys and of the actuators by the control unit is then effected either by a control signal modulated on the power supply, via additional contact tracks for control signal transmission which are not shown in the drawing and are parallel to the current-carrying rails 37 , 38 shown or via an infrared remote control. The continuous power and control signal supplied to the spotlight independently of their position make it possible for them to change their position even during use, permitting novel and spectacular lighting effects during performances, for example at rock concerts. However, because the rotary device according to the invention is provided with an actuator with quiet force transmission via a plastics gear wheel, a lamp can be readily moved, for example in television studios during a broadcast, ensuring greater flexibility in comparison with conventional lighting systems and in particular permitting work with fewer spotlights. Finally, it should also be mentioned that the rotary device described above is by no means the only possible embodiment of the invention and can also be modified in many respects. Thus, for example, it is entirely possible for the entire power supply to operate on the basis of three-phase current, in which case the number of contact tracks 38 , 39 would of course correspondingly increase. It is also entirely possible for a rail support 2 to have more than one rail section 52 . If, for example, two intersecting rail sections making an angle of 90° with one another are mounted on each rail support 2 , the maximum angle through which the rail support has to be turned before a transport unit 70 can be moved from a predetermined stationary rail onto one of its rail sections can be reduced to 45°. In this way, the speed with which the positions of the transport units 70 can be adapted can additionally be increased. It is of course also possible for the structure of the transport rail system to differ from the embodiment shown schematically in FIG. 5 . The rotary device can be installed, for example, in such a way that one rotary device is directly adjacent to the next one, so that the transport units can travel directly from one rail support 2 to the next one without having to travel over fixed rails. In this case, the pivot bearing 1 would of course have not eight rail attachments 21 to 28 but, for example, only four thereof, which would run in the diagonal directions of the transport system. It is not only lamps which are suitable transport units. For example, it is also entirely possible for television cameras, loudspeaker boxes, etc. by themselves or in combination with lamps to be positioned in a flexible and mobile manner on a transport rail system provided with the rotary devices according to the invention. The rotary device is of course also suitable for applications other than for the entertainment sector, for example for use for program-controllable transport devices in a warehouse.

The invention relates to a rotary device for use for lighting systems which ensure flexible and, if required, even mobile illumination of a room, for example of a television studio. The rotary device according to the invention is mounted at intersections of a transport rail system for conveying transport units, for example lamps. It has two components which can be rotated relative to one another and of which one is in the form of a pivot bearing, serving for fastening at the intersection, for the other, while the other is a rail support containing at least one rail section. According to the invention, each rail section of the rail support is provided with contact tracks so that the transport unit present on the rail section and having current collectors can obtain energy.

The present application is a continuation application of PCT application No. PCT/JP01/09695 filed on Nov. 6, 2001, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to shape processors and methods for representing shape. 2. Description of the Related Art So far, as methods for representing the shape of an object in a three-dimensional space, there are two known methods. One is the polygon mesh method which uses polygons to imitate the outline of an object and describe the shape by the vertices, edges and faces of the polygons used. The other is the CSG (Constructive Solid Geometry) method which uses reference blocks, such as cuboids, spheres and cylinders, to imitates the shape. In the method the shape is represented as a set of the reference blocks. In these methods, an object is decomposed into a set of components and the shape of the object is described by specifying the shape of the components and their positions. Thus, some objects may require a lot of computation for their decomposition. And some objects may require a large amount of data to describe the shape of the components and their positions, i.e., to describe their shapes. On the other hand, for example, in the field of chemistry, pharmacy and nano-technology, an efficient method to represent the structure of a polymer is required since the function of a polymer is often determined by its structure. The present invention aims to reduce the amount of computation and data to represent the shape of an object. SUMMARY OF THE INVENTION In order to solve the foregoing problem, according to a first aspect of the present invention, there is provided a shape processor for imitating a shape of an object in a two-dimensional space, comprising: an approximation unit operable to generate a chain of basic tiles which imitates the shape of the object by connecting a basic tile with a following tile by an edge one by one from an initial tile, wherein the basic tile includes a predetermined set of basic tiles of two-dimensional shapes; and a generation unit operable to generate a three-dimensional shape by specifying whether each basic block is assigned to corresponding basic space, wherein the basic block are assignable to each basic space, which is the convex hull of eight points of a lattice in a three-dimensional space, and the basic block includes one reference vertex and division lines, wherein the reference vertex corresponds to a vertex which is shared by the predetermined three faces that are to be projected onto the predetermined two-dimensional plane simultaneously, and the division line corresponds to the line drawn from the reference vertex to its opposite vertex of the corresponding face, the generation unit corresponds to a part or all of the chain of the divided faces obtained by projecting the divided faces into the two-dimensional space, wherein the divided faces are divided by the corresponding division line from the face of one or more of the basic block(s) assigned in the basic space, assigns each of the basic blocks to the corresponding basic space, and generates a three-dimensional shape that corresponds to the shape of an object so that two adjacent basic tiles in the basic tile chain corresponds a part or all of shape obtained by projecting the divided-faces of one basic block or two consecutive basic blocks in the three-dimensional space into the two-dimensional space. According to a second aspect of the present invention, there is provided a shape processor for imitating a shape of an object in a two-dimensional space, including a generation unit operable to generate three-dimensional shape defined by designating whether each basic blocks assignable to a basic space surrounded by eight points of a lattice in a three-dimensional space is to be assigned to the corresponding basic space, so that a two-dimensional shape, which is defined by projecting it into a direction where three faces of the basic block consisting of the three-dimensional shape may be seen, imitates the shape of the object, wherein the basic block is divided into two divided faces by a line connecting a reference vertex and a vertex positioned diagonally with respect to the reference vertex of the faces, wherein the reference vertex is a vertex shared by the three faces of the basic block, the generation unit executes: a first step of choosing one of the divided-faces of a basic block as the initial reference divided-face and one of the two edges of the initial reference divided-face that are edges of the corresponding basic block as the reference edge; a second step of choosing one of the two divided-faces which share the reference edge with the reference divided-face and whose image by the projection into the predetermined plane do not overlap with the image of the reference divided-face by the same projection, wherein the generation unit chooses the divided-face in such a way that the projection of the chosen divided-face imitates a part or all of the shape of the object; a third step of choosing the divided-face chosen in the second step as the new reference divided-face; and a fourth step of choosing the other edge of the new reference divided-face that is not the division line as the new reference edge, a chain of the divided-faces that were chosen as reference divided-faces during the execution is obtained by executing the steps from the second step to the fourth step repeatedly, the two-dimensional shape obtained by the projection of the chain into the predetermined plane imitates the shape of the object, and the generation unit generates a three-dimensional shape by assigning basic blocks that contains one of the divided-faces of the chain to their corresponding basic space. The generation unit may choose a set of points of the lattice to generate a three-dimensional shape by assigning basic blocks to all of the basic spaces which correspond to triangular pyramids defined by the chosen points of the lattice, and the generation unit may further include an administration unit operable to keeps the generated shape as a set of points. The generation unit may encode the generated shape by assigning a value 0 or 1 to each divided-faces of the chain according to the choice in the second step. According to a third aspect of the present invention, there is provided a shape processor for imitating a shape of an object in a three-dimensional space, including: an approximation unit operable to generate a chain of basic tiles which imitates the shape of the object by connecting a basic tile with a following tile by an face one by one from an initial tile, wherein the basic tile includes a predetermined set of basic tiles of three-dimensional shapes; and a generation unit operable to generate a four-dimensional shape by specifying whether each basic block is assigned to corresponding basic space, wherein the basic block are assignable to each basic space, which is the convex hull of sixteen points of a lattice in a four-dimensional space, the basic block includes four hyperfaces projected into the three-dimensional space, each of the four hyperfaces of the basic block is divided into six division hyperfaces by a division face, which is a face including either of a reference vertex shared by the four hyperface of the basic block, a vertex positioned opposite from the reference vertex on the hyperfaces, or another vertex on the hyperfaces, the generation unit corresponds to a part or all of the chain of the divided hyperfaces obtained by projecting the divided hyperfaces into the three-dimensional space, wherein the divided hyperface are included by each of the hyperfaces of the basic block assigned in the basic space, assigns each of the basic blocks to the corresponding basic space, and generates a four-dimensional shape so that two adjacent basic tiles in the basic tile chain corresponds a part or all of shape obtained by projecting the divided-hyperfaces of one basic block or two consecutive basic blocks in the four-dimensional space into the three-dimensional space. According to a fourth aspect of the present invention, there is provided a shape processor for imitating the shape of an object in a three-dimensional space, including a generation unit operable to generate four-dimensional shape defined by designating whether each basic blocks assignable to each basic space surrounded by sixteen points of a lattice in a four-dimensional space is to be assigned to the corresponding basic space, so that a three-dimensional shape, which is defined by projecting it into a direction where three hyperfaces of the basic block consisting of the four-dimensional shape maybe seen, imitates the shape of the object, wherein each of the hyperfaces of the basic block is divided into six divided hyperfaces by a division surface, which is a surface including either of a reference vertex which is a vertex shared by the four hyperfaces of the basic block projected into the projection direction, a vertex located opposite from the reference vertex on the hyperfaces, or another vertex on the hyperface, the generation unit executes: a first step of choosing one of the divided-hyperfaces of a basic block as the initial reference divided-hyperface and one of the two faces of the initial reference divided-hyperface that are faces of the corresponding basic block as the reference face; a second step of choosing one of the two divided-hyperfaces which share the reference face with the reference divided-hyperface and whose image by the projection into the predetermined plane do not overlap with the image of the reference divided-hyperface by the same projection, wherein the generation unit chooses the divided-hyperface in such a way that the projection of the chosen divided-hyperface imitates a part or all of the shape of the object; a third step of choosing the divided-hyperface chosen in the second step as the new reference divided-hyperface; and a fourth step of choosing the other face of the new reference divided-hyperface that is not the division line as the new reference face, a chain of the divided-hyperfaces that were chosen as reference divided-hyperfaces during the execution is obtained by executing the steps from the second step to the fourth step repeatedly, the three-dimensional shape obtained by the projection of the chain into the predetermined plane imitates the shape of the object, and the generation unit generates a four-dimensional shape by assigning basic blocks that contains one of the divided-hyperfaces of the chain to their corresponding basic space. The generation unit may choose a set of points of the lattice to generate a four-dimensional shape by assigning basic blocks to all of the basic spaces which correspond to triangular pyramids defined by the chosen points of the lattice, and the generation unit may further include an administration unit operable to keeps the generated shape as a set of points. The generation unit may encode the generated shape by assigning a value 0 or 1 to each divided-faces of the chain when one choose them in the second step. According to a fifth aspect of the present invention, there is provided a shape processor for imitating the structure of a polymer in a three-dimensional space, including an approximation unit operable to generate a chain of basic tiles to imitates a part or all of the structure of a polymer, wherein the shape of the basic tile is a kind of tetrahedron, that is, a three-dimensional shape with four vertices, and the chain of basic tiles is generated by connecting a basic tile with the following tile by an face one by one from a initial tile. The shape processor may further include a generation unit operable to generate a four-dimensional shape defined by the assignment of the basic block by specifying whether each basic block is assigned to corresponding basic space, wherein the basic block are assignable to each basic space, which is the convex hull of sixteen points of a lattice in a four-dimensional space, the basic block may include four hyperfaces projected into the three-dimensional space, each of the four hyperfaces of the basic block may be divided into six division hyperfaces by a division face, which is a face including either of a reference vertex shared by the four hyperface of the basic block, a vertex positioned opposite from the reference vertex on the hyperfaces, or another vertex on the hyperfaces. The generation unit may correspond to a part or all of the chain of the divided hyperfaces obtained by projecting the divided hyperfaces into the three-dimensional space, wherein the divided hyperfaces are included by each of the hyperfaces of one or more of the basic block(s) assigned in the basic space, may assign each of the basic blocks to the corresponding basic space, and may generate the four-dimensional shape that corresponds to a part or all of the structure of the polymer so that two adjacent basic tiles in the basic tile chain corresponds a part or all of shape obtained by projecting the divided-hyperfaces of one basic block or two consecutive basic blocks in the four-dimensional space into the three-dimensional space. The shape processor may further include a generation unit operable to generate four-dimensional shape defined by designating whether each basic blocks assignable to each basic space surrounded by sixteen points of a lattice in a four-dimensional space is to be assigned to the corresponding basic space, so that a three-dimensional shape, which is defined by projecting it into a direction where three hyperfaces of the basic block consisting of the four-dimensional shape may be seen, may imitate the chain of basic tiles, wherein each of the hyperfaces of the basic block is divided into six divided hyperfaces by a division surface, which is a surface including either of a reference vertex which is a vertex shared by the four hyperfaces of the basic block projected into the projection direction, a vertex located opposite from the reference vertex on the hyperfaces, or another vertex on the hyperface. The generation unit may execute: a first step of choosing one of the divided-hyperfaces of a basic block as the initial reference divided-hyperface and one of the two faces of the initial reference divided-hyperface that are faces of the corresponding basic block as the reference face; a second step of choosing one of the two divided-hyperfaces which share the reference face with the reference divided-hyperface and whose image by the projection into the predetermined plane do not overlap with the image of the reference divided-hyperface by the same projection, wherein the generation unit chooses the divided-hyperface in such a way that the projection of the chosen divided-hyperface imitates a part or all of the structure of the polymer; a third step of choosing the divided-hyperface chosen in the second step as the new reference divided-hyperface; and a fourth step of choosing the other face of the new reference divided-hyperface that is not the division line as the new reference face. A chain of the divided-hyperfaces that were chosen as reference divided-hyperfaces during the execution is obtained by executing the steps from the second step to the fourth step repeatedly, the three-dimensional shape obtained by the projection of the chain into the predetermined plane imitates a part or all of the structure of the polymer, and the generation unit generates a four-dimensional shape by assigning basic blocks that contains one of the divided-hyperfaces of the chain to their corresponding basic space. The generation unit may choose a set of points of the lattice to generate a four-dimensional shape by assigning basic blocks to all of the basic spaces which correspond to four-dimensional version of square pyramids defined by the chosen points of the lattice, and the generation unit further includes an administration unit operable to keep the generated shape as a set of points. The generation unit may encode the structure of a polymer by assigning a value 0 or 1 to each divided-faces of the chain when one choose them in the second step. The basic tile may include four vertices: A, B, C and D, the approximation unit generates a chain of basic tiles which imitates a part or all of the structure of the polymer by connecting a basic tile from the initial tile with a following tile sequentially such that three vertices C, D and B of the basic tile are coincide with vertices A, B and C of the following basic tile respectively, or three vertices C, D and A of the basic tile are coincide with vertices A, B and D of the following basic tile respectively. The generation unit may encode a part or all of the structure of a polymer by assigning a value 0 or 1 to each basic tile of the chain which imitates the structure, where the assigned value denotes the way the basic tile is connected with the following basic tile. The polymer may include a protein, and the generation unit imitates the structure of a chain of amino-acids which is a part or all of the protein, where one amino-acid corresponds to three consecutive basic tiles. The polymer may include a DNA molecule, and the generation unit imitates the structure of a chain of nucleotides which is a part or all of the DNA molecule, where one nucleotides corresponds to one basic tile. According to a sixth aspect of the present invention, there is provided a method for representing the structure of a polymer in a three-dimensional space, wherein the structure includes a predetermined set of basic tiles of three-dimensional shapes, each of which is associated with four vertices A, B, C and D which form a tetrahedron, a part or all of the structure of the polymer is imitated by a chain of basic tiles which is generated by connecting a basic tile from an initial tile with a following tile by face sequentially such that three vertices C, D and B of a basic tile are coincide with vertices A, B and C of the following basic tile respectively, or three vertices C, D and A of a basic tile are coincide with vertices A, B and D of the following basic tile respectively. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a configuration of a shape processing system 100 according to a first embodiment of the present invention; FIG. 2 shows a configuration of a shape processing unit 120 according to the first embodiment; FIG. 3 shows the shape of a basic block 300 used in the first embodiment; FIG. 4 is the projection of the basic block 300 into the predetermined two-dimensional plane; FIG. 5 shows an example of a three-dimensional shape 400 generated in the first embodiment; FIG. 6 shows the projection of the three-dimensional shape 400 onto the predetermined two-dimensional plane; FIG. 7 shows an example of a data format of vertices in the vertex-table of an administration-table-set 230 used in the first embodiment; FIG. 8 shows an example of a data format of vertices in the shape-table of an administration-table-set 230 used in the first embodiment; FIG. 9 shows the procedure performed by the shape processing unit 120 for the first embodiment of the present invention; FIG. 10 illustrates an example of the procedure performed by the generation unit 210 to generate a chain B 420 of the basic blocks in order to embody the first embodiment of the present invention; FIG. 11 shows the shape of a basic block 900 used in the second embodiment; FIG. 12 shows the correspondence between a set of basic blocks and a chain of basic tiles used in the second embodiment by comparing the second embodiment with the first embodiment; FIG. 13 shows two types of connections of basic tiles used in the second embodiment; FIG. 14 shows an example of a chain of basic tiles used in the second embodiment; FIG. 15 shows an example of a set of vertices in the vertex-table of the administration-table-set 230 used in the second embodiment; FIG. 16 shows an example of a set of vertices in the shape-table of the administration-table-set 230 used in the second embodiment; FIG. 17 shows the procedure performed by the shape processing unit 120 for the second embodiment of the present invention; FIG. 18 is an outline of the structure of an amino-acid and a protein (polypeptide); FIG. 19 shows a code of a hormone (insulin, human) encoded by the shape processing unit 120 which embodies the second embodiment; FIG. 20 shows a three-dimensional shape which imitates the shape of a hormone (insulin, human) and is generated by the shape processing unit 120 which embodies the second embodiment; FIG. 21 is an outline of the structure of a DNA molecule; FIG. 22 shows a three-dimensional shape which imitates the shape of a DNA molecule and is generated by the shape processing unit 120 which embodies the second embodiment; and FIG. 23 shows hardware components of the shape processing unit 120 according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION In the following several embodiments of the present invention are illustrated using the accompanying figures. The First Embodiment of the Present Invention FIG. 1 shows a configuration of a shape processing system 100 according to a first embodiment of the present invention. The shape processing system 100 comprises a shape input unit 110 , a shape processing unit 120 , a terminal 130 , and a shape output unit 140 . The shape input unit 110 receives data of the shape of an object in a two-dimensional space which is to be processed by the shape processing system 100 . And the shape input unit 110 converts the data (which is analogue) into digital data for manipulations by the shape processing unit 120 . The shape input unit 110 may be an input device such as a camera, a video recorder (video camera) and a scanner. Or the shape input unit 110 may be a mere interface to networks or files. The format of digital data converted by the shape input unit 110 may be any format for shape representation such as bit map, JPEG, MPEG, GIF, or polygon-mesh. The shape processing unit 120 receives the digital data from the shape input unit 110 , generates a corresponding three-dimensional shape and stores the shape. The shape processing unit 120 also performs various manipulations such as shape transformation of three-dimensional shape. three-dimensional shape and stores the shape. The shape processing unit 120 also performs various manipulation such as shape transformation of three-dimensional shape. Moreover the shape processing unit 120 converts data of the three-dimensional shape into data for two-dimensional representation such as bit map, JPEG, MPEG, GIF, or polygon-mesh to reproduce the two-dimensional shape. The terminal 130 is used by a user of the shape processing system 100 to control the shape processing unit 120 when he/she performs a shape transformation of a stored three-dimensional shape or a reproduction of a two-dimensional shape. The shape output unit 140 outputs a two-dimensional shape reproduced by the shape processing unit 120 . The shape output unit may be a mere interface to networks or files. FIG. 2 shows a configuration of the shape processing unit 120 according to a first embodiment. The shape processing unit 120 comprises an approximation unit 200 , a generation unit 210 , an administration unit 220 , an administration-table-set 230 , a processing unit 240 , a reproduction unit 250 and an output unit 260 . The approximation unit 200 receives digital data of two-dimensional shape converted from an input by the shape input unit 110 . Connecting predetermined two-dimensional basic tiles one by one, the approximation unit 200 generates a chain of basic tiles which imitates the shape of an object. The generation unit 210 transforms a chain of basic tiles generated by the approximation unit 200 into the corresponding three-dimensional shape. Moreover the generation unit 210 encodes the chain of basic tiles. The administration unit 220 stores a three-dimensional shape and/or the corresponding code generated by the generation unit 210 in the administration-table-set 230 and administrates the tables. A three-dimensional shape is stored in the administration-table-set 230 as a set of points in a three-dimensional lattice. The code of the shape is also stored in the administration-table-set 230 . The processing unit 240 performs various kind of three-dimensional transformations such as rotation, translation or deformation via the administration unit 220 under the directions from a user of the terminal 130 . The reproduction unit 250 receives data of a three-dimensional shape stored in the administration-table-set 230 via the administration unit 220 and converts data of the three-dimensional shape into data for two-dimensional representation such as bit map, JPEG, MPEG, GIF, or polygon-mesh to reproduce the corresponding two-dimensional shape. The output unit 260 outputs the two-dimensional shape reproduced by the reproduction unit 250 as a file or displays the shape on a display device. FIG. 3 shows the shape of the basic block 300 used in the first embodiment. The basic block 300 is a cube defined by three vectors ex, ey and ez of length 1. In this embodiment, the basic block is defined by ex=(1, 0, 0), ey=(0, 1, 0) and ez=(0, 0, 1) and is projected along the direction of (−1, −1, −1) into a plane which is perpendicular to (−1, −1, −1). The basic block 300 has one reference vertex 310 and three division lines 320 a , 320 b and 320 c . The reference vertex 310 is the nearest vertex of the basic block 300 to the point (−1, −1, −1). Thus the reference vertex is contained in all of the three upper faces of the basic block 300 . (Here ‘upper’ is considered w.r.t. the direction from bottom (0, 0, 0) to top (−1, −1, −1)) The division line 320 a is the segment connecting the reference vertex 310 and the opposite vertex 350 a with respect to the upper face of the basic block 300 specified by z=0. The division line 320 b is the segment connecting the reference vertex 310 and the opposite vertex 350 b with respect to the upper face of the basic block 300 specified by y=0. And the division line 320 c is the segment connecting the reference vertex 310 and the opposite vertex 350 c with respect to the upper face of the basic block 300 specified by x=0. The three-dimensional space used in this embodiment to represent shapes of objects is equipped with a three-dimensional lattice structure whose unit convex hull is identical to the basic cube 300 . We call a unit convex hull of the lattice a “basic space”. That is, a basic space is a convex hull of eight points of the lattice. And the shape of an object is represented using the lattice points of the space. FIG. 4 is the projection of the basic block 300 into a predetermined two-dimensional plane. The image of the basic block 300 by the projection is a hexagon whose center coincides with the image of the reference vertex 310 . Moreover the hexagon is divided into six divided-faces 360 a , . . . , 360 f which are congruent equilateral triangles by three division lines 320 a , 320 b and 320 c and three vectors ex, ey and ez. We call the equilateral-triangles-shaped divided-faces 360 a , . . . , 360 f “basic tiles”. The approximation unit 200 generates a chain of basic tiles, which imitates the shape of an object conveyed from the input unit 110 , connecting a basic tile with another basic tile by an edge which is not any division line one by one. The generation unit 210 generates a three-dimensional shape by assigning basic blocks to basic spaces. Basic blocks are assigned in such a way that the shape of an object conveyed from the input unit 110 is imitated by the chain of basic tiles obtained by projecting a part of the resulting three-dimensional shape along the vector (−1, −1, −1) into the predetermined two-dimensional plane. Instead of the basic block 300 , the shape processing unit 120 may use a three-dimensional block with curved edges and curved faces as a basic block. Or the shape processing unit 120 may use a basic block where some of the division lines are curves. And the shape processing unit 120 may project basic blocks along another vector into another plane. For example, (−2, −1, −1) will do. In that case, the projected image of the basic block 300 is divided into six triangles which are not equilateral and basic tiles are no longer equilateral triangles. But the generation unit 210 can generate a chain of basic tiles similarly. Moreover, the shape processor may use three vectors ex, ey and ez of different lengths. (Then the basic block is a cuboid.) FIG. 5 shows an example of a three-dimensional shape 400 generated in the first embodiment. The three-dimensional shape 400 corresponds to two chains A 410 and B 410 of basic tiles. And each of two chains of divided-faces (on the three-dimensional shape) that corresponds to chain A 410 and B 410 is composed of fourteen divided-faces. The part of the three-dimensional shape which corresponds to chain A 410 is a union of four triangular pyramids (without bases). The four triangular pyramids are (1) the pyramid whose peak (top vertex) is the reference vertex of a basic block 430 a which corresponds to a lattice point A and slopes are defined by three (upper) faces of basic block 430 a , (2) the pyramid whose peak is the reference vertex of a basic block 430 b which corresponds to a lattice point B and slopes are defined by three (upper) faces of basic block 430 b , (3) the pyramid whose peak is the reference vertex of a basic block 430 c which corresponds to a lattice point C and slopes are defined by three (upper) faces of basic block 430 c and (4) the pyramid whose peak is the reference vertex of a basic block 430 d which corresponds to a lattice point D and slopes are defined by three (upper) faces of basic block 430 d . The part of the three-dimensional shape which corresponds to chain B 410 is a union of three triangular pyramids. The three triangular pyramids are (1) the pyramid whose peak is the reference vertex of a basic block 430 d which corresponds to a lattice point D and slopes are defined by three (upper) faces of basic block 430 d , (2) the pyramid whose peak is the reference vertex of a basic block 430 e which corresponds to a lattice point E and slopes are defined by three (upper) faces of basic block 430 e and (3) the pyramid whose peak is the reference vertex of a basic block 430 f which corresponds to a lattice point F and slopes are defined by three (upper) faces of basic block 430 f . In this way, the generation unit 210 transforms a chain of basic tiles received from the input unit 200 into a three-dimensional shape which consists of triangular pyramids whose peaks (top vertices) are points of a lattice in a three-dimensional space. The three faces of a triangular pyramid are defined by three (upper) faces of a basic block whose reference vertex coincides with the peak of the triangular pyramid. And the corresponding three-dimensional shape is obtained by assigning (one of an infinite number of) basic blocks to an area covered by the triangular pyramid. In particular, the generation unit 210 specifies a three-dimensional shape by its peaks. FIG. 6 shows the projected image of three-dimensional shape 400 in the predetermined two-dimensional plane. As shown in the FIG. 6 , the chain of divided-faces which corresponds to chain A 410 of basic tiles is mapped onto a chain of equilateral triangles in the plane. And the chain of divided-faces which corresponds to chain B 410 is also mapped onto such a chain. When the shape processing system 120 processes the shape of an object in a two dimensional space, the approximation unit 200 imitates the shape with a set of chains of basic tiles such as chains A 410 and B 420 and the generation unit 210 transforms the chains of (two-dimensional) basic tiles into a three-dimensional shape such as shape 400 . And when the shape processing unit 120 reproduces a two-dimensional shape from its corresponding three-dimensional shape stored in the administration-table-set 230 , the reproducing unit 250 fetches data of a three-dimensional shape in the administration-table-set 230 via the administration unit 220 and reproduces the corresponding two-dimensional shape such as chains A 410 and B 420 . FIG. 7 shows an example of a data format of vertices stored in the vertex-table of the administration-table-set 230 used in the first embodiment. An entry of the vertex-table consists of an ID-of-shape field and a coordinates-of-vertex filed. An ID-of-shape field contains an identifier of the corresponding shape stored in the administration-table-set 230 . In FIG. 7 the identifier of chain A 410 (resp. B 420 ) of basic tiles is 001 (resp. 002). A coordinates-of-vertex field contains the cartesian coordinates in three dimensions of a peak of the corresponding three-dimensional shape. The administration unit 220 administers three-dimensional shapes that correspond to the shape of a two-dimensional object using data of their peaks in the vertex-table. FIG. 8 shows an example of a data format of vertices stored in the shape-table of the administration-table-set 230 used in the first embodiment. An entry of the shape-table of the administration-table-set 230 consists of an ID-of-shape field, an initial-tile field, a terminal-tile field and a code field. An ID-of-shape field contains an identifier of the corresponding shape stored in the administration-table-set 230 . In FIG. 8 , the identifier of chain A 410 (resp. B 420 ) of basic tiles is 001 (resp. 002). An initial-tile field contains the data of the initial divided-face of the corresponding chain of divided-faces. In FIG. 8 , the initial divided-face of chain A 410 is specified by reference vertex (−1, 2, −1) which we denote by C. The vertices of the initial divided-face are C, C+ex and C+ex+ey. (Recall that ex, ey and ez are the vectors used to define basic blocks.) A terminal-tile field the data of the terminal divided-face of the corresponding chain of divided-faces. In FIG. 8 , the terminal divided-face of chain A 410 is specified by reference vertex (−1, 2, −1), i.e., C. The vertices of the terminal divided-face are C, C+ex and C+ex+ez. A code field contains the code of the corresponding chain of divided-faces. The administration unit 220 administers the chain of divided-faces which corresponds to the shape of a two-dimensional object using data of the initial tile, the terminal tile and the code of the chain of divided-faces in the shape-table. FIG. 9 shows the procedure performed by the shape processing unit 120 for the first embodiment of the present invention. As explained bellow, the flow chart in FIG. 9 illustrates the procedure to transform the shape of an object into the data format of the administration-table-set 230 and generate the code of the shape of the given object. First, the approximation unit 200 receives the shape of an object in a two-dimensional space from the input unit 110 (S 700 ). And the approximation unit 200 generates a chain of basic tiles which imitates the shape of the given object (S 710 ) Next, the generation unit 210 chooses one of three divided-faces of a basic tile of the chain as the initial reference divided-face and one of two edges of the reference divided-face which are not the division line (, that is, which are also edges of the corresponding basic block,) as the reference edge (S 720 ). And the generation unit 210 assigns a symbol of code, which reflects the shape of the given object, to the initial reference divided-face as the initial symbol of the code of the object. In this embodiment, where the direction from up to down is defined by the vector ex+ey+ez, the generation unit 210 assigns symbol “0” (or “D”) to the reference divided-face when the reference edge corresponds to the lower edge of the reference divided-face and “1” (or “U”) when the reference edge corresponds to the upper edge of the reference divided-face. Next, the generation unit 210 chooses one of two divided-faces which share the reference edge with the reference divided-face and whose image by the projection into the predetermined plane do not overlap with the image of the reference divided-face by the same projection (S 730 ). The generation unit 210 chooses the divided-face in such a way that the projection of the chosen divided-face imitates a part or all of the shape of the given object. In this embodiment, the image of a divided-face by the projection overlaps with the image of another divided-face when both of the divided-face correspond the same basic tile. Next, the generation unit 210 chooses the divided-face chosen in the step of S 730 as the new reference divided-face (S 740 ). And the generation unit 210 appends a symbol “0” (or “D”) or “1” (or “U”) to the right end of the code as the symbol which corresponds to the new reference divided-face. Next, the generation unit 210 chooses the edge of the new reference divided-face that is not the division line and not chosen in the step of S 730 as the new reference edge (S 750 ). The generation unit 210 executes steps S 730 , S 740 , S 745 and S 750 repeatedly until the shape of the given object is imitated by the obtained chain of divided-faces (S 760 ). Finally, the generation unit 210 transforms the obtained chain of divided-faces into a three-dimensional shape and stores all peaks of the three-dimensional shape in the vertex-table of the administration-table-set 230 (S 770 ). The generation unit 210 also stores the initial and terminal divided-face of the chain and the code obtained by the above procedure in the shape-table of the administration-table-set 230 (S 780 ). As explained above, the generation unit generates a chain of divided-faces by repeated executions of steps S 730 , S 740 , S 745 and S 750 . And the shape of the given object is imitated by the two-dimensional shape obtained by projecting the chain of divided-faces into the predetermined plane. The generation unit 210 also generates the corresponding three-dimensional shape by assigning basic blocks which include one of the divided-faces of the chain to the corresponding basic spaces. Recall that, for each point of a lattice, there exists a basic block 300 whose reference vertex 310 is given by the point and it defines a triangular pyramid whose peak (top vertex) is the reference vertex and the slopes are defined by the predetermined three faces of the basic block. (Note that pyramids are without bases.) The generation unit 210 generates a three-dimensional shape by assigning all basic blocks which are covered by a set of triangular pyramids to the corresponding basic spaces. Thus a three-dimensional shape generated in the above procedure is specified by peaks of all triangular pyramids. And the administration unit 220 stores peaks of all triangular pyramids in the administration-table-set 230 and uses the peaks to administer the three-dimensional shape. Moreover the generation unit 210 may encode the shape of the given object by assigning either value 0 or 1 to each divided-face of the chain in step S 745 . The choice of value reflects the choice of divided-face in the step S 740 . FIG. 10 illustrates an example of the procedure performed by the generation unit 210 to generate chain B 420 of basic blocks in order to embody the first embodiment of the present invention. First, the generation unit 210 chooses a divided-face 800 a as the reference divided-face as shown in (1) of FIG. 10 . Here we suppose that the arrow in the figure ( 1 ) shows the direction from the upper edge to the lower edge of divided-face 800 a and the generation unit 210 chooses the lower edge as the reference edge. Then the generation unit 210 assign symbol “0” to the reference divided-face. Next, the generation unit 210 chooses divided-faces 800 b , 800 c and 800 d serially to imitate the shape of the object received from the approximation unit 200 as shown in (2) of FIG. 10 . It is arranged such that two consecutive divided-faces share the same gradient when their division lines don't intersect. (Recall there is one division line for each divided-face.) In the case of the figure ( 2 ), divided-face 800 a and 800 b share the same gradient. Divided-face 800 b and 800 c also share the same gradient. On the other hand, it is arranged such that two consecutive divided-faces do not share the same gradient when their division lines share an end point as in the case of divided-faces 800 c and 800 d in (2) of FIG. 10 . Then the generation unit 210 assigns symbol “0” to divided-faces 800 b and 800 c since they slope down. And the generation unit 210 assigns symbol “1” to divided-face 800 d since it slopes up. The generation unit 210 transforms a chain of basic tiles which imitates the shape of the given object into a chain of divided-face in a three-dimensional space in such a way explained above. In (3) of FIG. 10 , arrows on basic tiles of a chain show the gradient (the direction from up to down) of the basic tiles. Considering the directions, the generation unit 210 assigns a divided-face in a three-dimensional space to each of the basic tiles. The generation unit 210 generates a three-dimensional shape by assigning basic blocks which contain one of the divided-faces to the corresponding basic spaces. And the generation unit 210 assign either “0” or “1” to each basic tile of the chain, where the choice depends on the direction. (“0” when it slopes down and “1” when it slops up.) In this way, the chain of divided-faces in (3) is transformed into a three-dimensional shape which coincides with the part of shape 400 in FIG. 5 which corresponds to chain B 420 of basic tiles. As explained above, the generation unit 210 generates a three-dimensional shape from a chain of basic tiles by assigning basic blocks 300 to the corresponding basic space. The assignment is done in such a way that the chain of basic tiles corresponds to a part or all of the projection of divided-faces of the assigned basic blocks. (Recall that each basic block 300 has six divided-faces that are obtained by dividing three faces of a basic block by the division lines 320 a , 320 b and 320 c .) And the generation unit 210 generates a three-dimensional shape from a chain of basic tiles in such a way that each pair of consecutive basic tiles of the chain corresponds to two divided-faces of one basic block or two consecutive basic blocks. The generated three-dimensional shape corresponds to the shape of the given object. As is shown above, the shape processing unit 120 according to the first embodiment transforms the shape of an object into a chain of basic tiles. And the shape processing unit 120 identifies the shape with peaks of a three-dimensional shape which corresponds to the chain of basic tiles. In this way, the shape processing unit 120 identifies various kind of shapes which are imitated by a number of basic tiles with a set of lattice points (i.e., peaks) in a three-dimensional space. Therefore, by using the shape processing unit 120 according to the first embodiment, one can save memory of a computer when he/she stores shapes of objects. Moreover one can rotate or/and translate the shape of an object with less amount of calculation. Furthermore, the shape processing unit 120 can encode the shape of an object assigning a sequence of symbols (“0” or “1”) to a chain of divided-faces which corresponds to the chain of basic tiles obtained from the shape of the object. That is, the shape processing unit 120 can encode any shape which is imitated by a sequence of basic tiles using only 1 bit for each basic tile. Thus, using the shape processing unit 120 , one needs less memory when he/she stores shapes of objects. The Second Embodiment of the Present Invention Now the second embodiment of the present invention is explained. The explanation is focused on the difference between the first embodiment and the second embodiment. The shape processing unit 120 according to a second embodiment generates a chain of basic tiles in a three-dimensional space to imitate the shape of an object, transforms the chain of basic tiles into a four-dimensional shape, and finally stores the four-dimensional shape in a storage. FIG. 11 shows the shape of a basic block 900 used in the second embodiment. (In fact, their projected image into a three-dimensional space.) Basic block 900 is a cube in a four-dimensional space defined by four vectors ex, ey, ez and ew of length 1. which are perpendicular to each other. By projecting into a three-dimensional-space, basic block 900 is mapped onto a three-dimensional shape which consists of images of four (three-dimensional) faces 910 a , 920 b , 910 c and 910 d of the block. Since faces 910 a , 920 b , 910 c and 910 d correspond to hyperfaces in a four-dimensional space (as faces of a three-dimensional cube correspond to plane in a three-dimensional space), we call them “hyperfaces”. Four hyperfaces 910 a , 920 b , 910 c and 910 d share a vertex O which is called the “reference vertex” of basic block 900 . Hyperface 910 a is a hexahedron which contains reference vertex O and defined by three vectors ey, ez and ew. Hyperface 910 a has eight vertices O, A 1 , C 1 a , C 1 b , C 1 c , C 1 d , C 1 e and C 1 f . Vertex A 1 is the opposite vertex of reference vertex O. In hyperface 910 a , we define six division faces by 3-tuple of vertices: reference vertex O, vertex A 1 and one of the other vertices C 1 a , C 1 b , C 1 c , C 1 d , C e and C 1 f . And hyperface 910 a is divided into six divided-hyperfaces by six division faces OA 1 C 1 a , OA 1 C 1 b , OA 1 C 1 c , OA 1 C 1 d , OA 1 C 1 e and OA 1 C 1 f , where OA 11 a denotes the convex-hull of three points O, A 1 and C 1 a (, i.e., a two-dimensional region in a three-dimensional space). Hyperface 910 b is a hexahedron which contains reference vertex O and defined by three vectors ex, ey and ez. Hyperface 910 b has eight vertices O, A 2 , C 2 a , C 2 b , C 2 c , C 2 d , C 2 e and C 2 f . Vertex A 2 is the opposite vertex of reference vertex O. In hyperface 910 b , we define six division faces by 3-tuple of vertices: reference vertex O, vertex A 2 and one of the other vertices C 2 a , C 2 b , C 2 c , C 2 d , C 2 e and C 2 f . And hyperface 910 b is divided into six divided-hyperfaces by the six division faces. Hyperface 910 c is a hexahedron which contains reference vertex O and defined by three vectors ex, ez and ew. Hyperface 910 c has eight vertices O, A 3 , C 3 a , C 3 b , C 3 c , C 3 d , C 3 e and C 3 f . Vertex A 3 is the opposite vertex of reference vertex O. In hyperface 910 c , we define six division faces by 3-tuple of vertices: reference vertex O, vertex A 3 and one of the other vertices C 3 a , C 3 b , C 3 c , C 3 d , C 3 e and C 3 f . And hyperface 910 c is divided into six divided-hyperfaces by the six division faces. Hyperface 910 d is a hexahedron which contains reference vertex O and defined by three vectors ex, ey and ew. Hyperface 910 d has eight vertices O, A 4 , C 4 a , C 4 b , C 4 c , C 4 d , C 4 e and C 4 f . Vertex A 4 is the opposite vertex of reference vertex O. In hyperface 910 d , we define six division faces by 3-tuple of vertices: reference vertex O, vertex A 4 and one of the other vertices C 4 a , C 4 b , C 4 c , C 4 d , C 4 e and C 4 f . And hyperface 910 d is divided into six divided-hyperfaces by the six division faces. The four-dimensional space used in this embodiment to represent the shape of an object is equipped with a four-dimensional lattice structure whose unit cube is identical to basic cube 900 . We call unit cubes of the lattice “basic spaces”, i.e., a basic space is a convex hull of sixteen points of the lattice. And the shape of an object is represented using lattice points of the space. We call the tetrahedron-shaped divided-hyperfaces of hyperfaces 910 a , 910 b , 910 c and 901 d “basic tiles”. Connecting a basic tile with another by an face which is not any division face, the approximation unit 200 generates a chain of basic tiles to imitate the shape of the object which is conveyed from the input unit 110 . The generation unit 200 generates a four-dimensional shape assigning basic blocks to basic spaces of a four-dimensional space with the lattice structure. Basic blocks are assigned in such a way that the shape of an object conveyed from the input unit 110 is imitated by the chain of basic tiles which is obtained by projecting a part or all of the resulting four-dimensional shape into a predetermined hyperface. Concretely speaking, the generation unit 200 generates a chain of divided-hyperfaces connecting by a face which is not any division face. (Note that there are two such faces for each divided-hyperface.) For example, the generation unit 210 connects basic tile 950 a to another basic tile by face OC 1 a C 1 b or face A 1 C 1 a C 1 b . The generation unit 210 maps a divided-hyperface in a four-dimensional space onto a basic tile in a three-dimensional space when the unit 210 projects a chain of divided-faces in the four-dimensional space into the three-dimensional space. The generation unit 210 generates a four-dimensional shape assigning basic blocks which contain one of the divided-hyperfaces of the chain and store it in the administration-table-set 230 . As a result, the chain of divided-hyperfaces in a four-dimensional space generated by the generation unit is projected onto a chain of basic tiles in a three-dimensional space. Instead of the basic block 900 , the shape processing unit 120 may use a four-dimensional block with curved edges, curved faces and/or curved hyperface as a basic block. Or the shape processing unit 120 may use a basic block where some of the division faces are curved faces. And the shape processing unit 120 may project basic blocks along another vector into a plane. In that case, the image of the basic block 900 may be divided into twenty-four divided-hyperfaces which are not identical. (Therefore, basic tiles are no longer identical). But the generation unit 210 can generate a chain of basic tiles similarly. Moreover, the shape processor may use four vectors ex, ey ez and ew of different lengths. FIG. 12 shows the correspondence between a set of basic blocks and a chain of basic tiles used in the second embodiment (by comparing the second embodiment with the first embodiment). The upper figure of FIG. 12 shows the correspondence of a set of basic blocks in a three-dimensional space to a chain of basic tiles in the case of the first embodiment. The left side of the upper figure of FIG. 12 shows the top elevation of a three-dimensional triangular pyramid without base whose peak is formed by a basic block 1000 d . In the left side of the upper figure of FIG. 12 , basic blocks 1000 a , 1000 b and 1000 c are contained in the triangular pyramid defined by reference vertex O and three faces of basic block 1000 d . The dotted line on basic blocks 1000 a , 100 b , 1000 c and 1000 d show division lines of the corresponding basic blocks. In particular, basic tile 1005 a is connected with basic tile 1005 b. The right side of the upper figure of FIG. 12 shows the top elevation of a three-dimensional shape which is obtained by removing basic block 1000 d from the triangular pyramid of the left side whose peak is formed by basic block 1000 d . Removing basic block 1000 d , we have three new peaks O 1 , O 2 and O 3 . Note that O 1 , O 2 and O 3 are reference vertices of the corresponding basic blocks and they are obtained by translating reference vertex O of the basic block 1000 d along vectors ex, ey and ez. In particular, this relationship induces an order relation among lattice points in a triangular pyramid, that is, (the position of) a lattice point is said to be higher than (the positions of) the lattice points obtained by translation of a lattice point along ex, ey or ez. Moreover, removing basic block 1000 d , faces of basic blocks 1000 a , 1000 b and 1000 c have come in sight. And accordingly the arrangement of division lines of basic tile 1005 a has changed. As a result, basic tile 1005 a is connected with basic tile 1005 c in right side of the upper figure of FIG. 12 . As explained above, in the first embodiment, the assignment of basic blocks in a three-dimensional space (i.e., the shape of a triangular pyramid which consists of the assigned basic blocks,) determines connections among basic tiles, therefore, chains of basic tiles. The lower figure of FIG. 12 shows the correspondence of basic blocks in a four-dimensional space to a chain of basic tiles in the case of the second embodiment. (Exactly speaking, it shows the correspondence between the projection of the basic blocks into a three-dimensional space and the projection of a chain of basic tiles into a three-dimensional space.) The left side of the lower figure of FIG. 12 is a perspective drawing of the projection of a four-dimensional version of square pyramid whose peak is the reference vertex of a basic block 1010 d and the four (three-dimensional) slopes are defined by the predetermined four (three-dimensional) faces of basic block 1010 d . (Note that 1010 d is a basic block in a four-dimensional space.) The dotted lines on basic block 1010 d show some edges of its division faces. And basic tile 1020 a is connected to basic tile 1020 c in the left side of the lower figure of FIG. 12 . The right side of the lower figure of FIG. 12 is a perspective drawing of the projection of a four-dimensional shape which is obtained by removing basic block 1010 d from the four-dimensional version of square pyramid whose peak is formed by basic block 1010 d (i.e., the left side of this figure). Removing basic block 1010 d , we have four new peaks O 1 , O 2 , O 3 and O 4 . Note that O 1 , O 2 and O 3 are reference vertices of the corresponding basic blocks and they are obtained by translating the reference vertex O of the basic block 1010 d along the vector ex, ey, ez and ew. In particular, this relationship induces an order relation among lattice points in a four-dimensional version of square pyramid, that is, (the position of) a lattice point is said to be higher than (the positions of) the lattice points obtained by translation of a lattice point along ex, ey ez or ew. Moreover, removing basic block 1010 d , (three-dimensional) faces of the basic blocks with reference vertices O 1 , O 2 , O 3 and O 4 have come in sight. And accordingly the arrangement of division faces of basic tile 1020 a has changed. As a result, basic tile 1020 a is connected with basic tile 1020 b in right side of the upper figure of FIG. 12 . As explained above, in the second embodiment, the assignment of basic blocks in a four-dimensional space (i.e., the shape of the four-dimensional version of a square pyramid which consists of the assigned basic blocks,) determines connections among basic tiles, therefore, chains of basic tiles. FIG. 13 shows two types of connections of basic tiles used in the second embodiment. Basic tile 1300 a is a three-dimensional object which is a kind of tetrahedron defined by four vertices A 1 , B 1 , C 1 and D 1 . Basic tile 1300 b is a three-dimensional object which is a kind of tetrahedron defined by four vertices A 2 , B 2 , C 2 and D 2 . Basic tiles 1300 a and 1300 b are comprised in a chain of basic tiles, where basic tile 1300 b follows basic tile 1300 a immediately. The approximation unit 200 connects basic tile 1300 b with the current end, i.e. tile 1300 a , of the chain under construction. A basic tile is connected with another tile in one of two ways by the approximation unit 200 as shown in FIG. 13 . In one way, three vertices C 1 , D 1 and A 1 of basic tile 1300 a are coincide with vertices A 2 , B 2 and D 2 of the following basic tile 1300 b respectively as is shown in the upper figure of FIG. 13 . In the other way, three vertices C 1 , D 1 and B 1 of basic tile 1300 a are coincide with vertices A 2 , B 2 and C 2 of the following basic tile 1300 b respectively as is shown in the lower figure of FIG. 13 . Connecting tiles one by one in such a way, the approximation unit 200 generates a chain of basic tiles to imitate a part or all of the shape of the given object in a three-dimensional space. A chain of basic tiles obtained in such a way explained above corresponds to a chain of divided-hyperface defined by a four-dimensional shape generated by the generation unit 210 . For example, basic tile 1300 a (resp. 1300 b ) in the upper figure of FIG. 13 corresponds to basic tile 1020 a (resp. 1020 c ) in FIG. 12 which is a projection of a divided-hyperface. And basic tile 1300 a (resp. 1300 b ) in the lower figure of FIG. 13 corresponds to basic tile 1020 a (resp. 1020 b ) in FIG. 12 . Using the two types of connections shown in FIG. 13 , the approximation unit 200 generates a chain of basic tiles to imitate the shape of the given object. And the generation unit 210 generates a chain of divided-hyperfaces which corresponds to the chain of basic tiles conveyed from the approximation unit 200 . Then the generation unit 210 stores a four-dimensional shape which corresponds to the chain of divided-hyperfaces. The stored shape is administered by the administration unit 220 . Moreover, the generation unit 200 may encode a chain of basic tiles by assigning a value 0 or 1 to each basic tile, where an assigned value denotes the way the corresponding basic tile is connected with the following basic tile. (As explained above, there are two ways of connection.) FIG. 14 shows an example 1250 of a chain of basic tiles used in the second embodiment. Chain 1250 consists of four basic tiles 1200 a , 1200 b , 1200 c and 1200 d. Basic tile 1200 a is the initial tile of chain 1250 . Recall that basic tile 1200 a is a projection of a divided-hyperface of a basic block with reference vertex O 1 into a three-dimensional space. That is, basic block 1200 a is a tetrahedron defined by projected images of four vertices O 1 , O 1 +ex, O 1 +ez+ew and O 1 +ez+ew+ex, where ex, ez and ew are the unit vectors used to define a basic block in a four-dimensional space. Suppose that a, b, c and d are integers. In the second embodiment, we denote a point in a four-dimensional space defined as the end point of vector a*ex+b*ey+c*ez+d*ew and denotes it by 4-tuple (a, b, c, d). And let the coordinate of 01 be (0,1,0,0). Recall that, as is shown in the lower figure of FIG. 12 , a lattice point is higher than lattice points which are obtained by translation of the lattice point along ex, ey, ez or ew. Now we introduce a notion of “height” of lattice points. A height is defined in such a way that the difference of height of points P and P+ex (or P+ey or P+ez or P+ew) is 1. For example, we can define a height of point (a, b, c, d) by a+b+c+d. In the followings we use this height function. Further, we consider height of the projected image of (a, b, c, d) into a three-dimensional space and also call value a+b+c+d the “height” of the image of (a, b, c, d) in a three-dimensional space. As explained above, basic tile 1200 a is a projection of a divided-hyperface of a basic block with reference vertex O 1 into a three-dimensional space, where the divided-hyperface is specified by three vectors ez, ew and ex. And the height of four vertices O 1 , O 1 +ex, O 1 +ez+ew and O 1 +ez+ew+ex are −1, −2, −3 and −4 respectively. Basic tile 1200 b is connected with basic tile 1200 a . Basic tile 1200 b is a projection of a divided-hyperface of a basic block with reference vertex O 2 into a three-dimensional space, where the divided-hyperface is specified by three vectors ey, ew and ex. That is, basic block 1200 b is a tetrahedron defined by the projection of four vertices O 2 , O 2 +ey, O 2 +ey+ew and O 2 +ey+ew+ex. And the height of four vertices O 2 , O 2 +ey, O 2 +ey+ew and O 2 +ey+ew+ex are −1, −2, −3 and −4 respectively. Basic tile 1200 c is connected with basic tile 1200 b . Basic tile 1200 c is a projection of a divided-hyperface of a basic block with reference vertex O 2 into a three-dimensional space, where the divided-hyperface is specified by three vectors ey, ew and ez. That is, basic block 1200 c is a tetrahedron defined by the projection of four vertices O 2 , O 2 +ey, O 2 +ey+ew and O 2 +ey+ew+ez. And the height of four vertices O 2 , O 2 +ey, O 2 +ey+ew and O 2 +ey+ew+ez are −1, −2, −3 and −4 respectively. Basic tile 1200 d is connected with basic tile 1200 c . Basic tile 1200 d is a projection of a divided-hyperface of a basic block with reference vertex O 3 into a three-dimensional space, where the divided-hyperface is specified by three vectors ex, ew and ez. That is, basic block 1200 d is a tetrahedron defined by the projection of four vertices O 3 , O 3 +ex, O 3 +ex+ew and O 3 +ex+ew+ez. And the height of four vertices O 3 , O 3 +ex, O 3 +ex+ew and O 3 +ex+ew+ez are −1, −2, −3 and −4 respectively. In the second embodiment, the generation unit 210 assigns symbols to chain 1250 of basic tiles using the height function. In details, the unit generation 210 assigns symbol “U” to a basic tile if the height of the vertex of the basic tile which is not contained in the succeeding basic tile is smaller than heights of three vertices which are shared between the basic tile and the succeeding basic tile. If not, the generation unit 210 assigns symbol “D” to the basic tile. For example, the height of point O 1 , whose projection is a vertex of basic tile 1200 a , is larger than the heights of points that corresponds to the contact face between basic tiles 1200 a and 1200 b . Thai is, −1 >−2, −3, −4. Thus the generation unit 210 assigns symbol “D” to basic tile 1200 a . In the case of basic tile 1200 b , the height of the vertex of basic tile 1200 b which is not contained in the succeeding basic tile 1200 c is −4. On the other hand, point O 2 is the highest among three points which correspond to the contact face between basic tiles 1200 b and 1200 c and the height of O 2 is −1. Since −4<−1, the generation unit 210 assigns symbol “U” to basic tile 1200 b . Continuing the process, the generation unit 210 assigns code “DUDU” to chain 1250 of basic tiles. FIG. 15 shows an example of a set of vertices in the vertex-table of the administration-table-set 230 used in the second embodiment. An entry of the vertex-table of the administration-table-set 230 consists of an ID-of-shape field and a coordinates-of-vertex filed. An ID-of-shape field contains an identifier of the corresponding shape stored in the administration-table-set 230 . In FIG. 15 the identifier of chain 1250 of basic tiles is 003 . A coordinates-of-vertex field contains the cartesian coordinates in four dimensions of a peak of the corresponding four-dimensional shape. The administration unit 220 administers four-dimensional shapes which correspond to the shape of a three-dimensional object using data of peaks of the four-dimensional shapes in the vertex-table. FIG. 16 shows an example of a set of vertices in the shape-table of the administration-table-set 230 used in the second embodiment. An entry of the shape-table of the administration-table-set 230 consists of an ID-of-shape field, an initial-tile field, a terminal-tile field and a code field. An ID-of-shape field contains an identifier of the corresponding shape stored in the administration-table-set 230 . In FIG. 16 , the identifier of chain 1250 of basic tiles is 003 . An initial-tile field contains the data of the initial divided-hyperface of the corresponding chain of divided-hyperfaces. In the FIG. 16 , the initial divided-hyperface of chain 1250 is specified by reference vertex O 1 =(0, 1, 0, 0). Vertices of the initial divided-hyperface are O 1 , O 1 +ez, O 1 +ez+ew and O 1 +ez+ew+ex. (Recall that ex, ey and ez are the vectors used to define basic blocks.) And the initial basic tile 1200 a is the projected image of the initial divided-hyperface. A terminal-tile field contains the data of the terminal divided-hyperface of the corresponding chain of divided-hyperfaces. In FIG. 16 , the terminal divided-face of chain 1250 is specified by reference vertex O 3 =(−1, 1, 1, 0). Vertices of the terminal divided-hyperface are O 3 , O 3 +ex, O 3 +ex+ew and O 3 +ex+ew+ez. And the terminal basic tile 1200 d is the projection of the terminal divided-hyperface. A code field contains the code of the corresponding chain of divided-hyperfaces. The administration unit 220 administers the chain of divided-hyperfaces which corresponds to the shape of a three-dimensional object using data of the initial tile, the terminal tile and the code (of the chain of divided-hyperfaces) in the shape-table. FIG. 17 shows the procedure performed by the shape processing unit 120 for the second embodiment of the present invention. As explained bellow, the flow chart in FIG. 17 illustrates the procedure to transform the shape of an object into the data format of the administration-table-set 230 and generate the code of the shape of the given object. First, the approximation unit 200 receives the shape of an object in a three-dimensional space from the input unit 110 (S 1600 ). And the approximation unit 200 generates a chain of basic tiles to imitate the shape of the given object (S 1610 ). Next, the generation unit 210 chooses one of six divided-hyperfaces of a basic tile of the chain as the initial reference divided-hyperface and one of two faces of the reference divided-hyperface which are not the division face (that is, which are also faces of the corresponding basic block,) as the reference face (S 1620 ). And the generation unit 210 assigns a symbol of code, which reflects the shape of the given object, to the initial reference divided-hyperface as the initial symbol of the code of the object (S 1625 ). In this embodiment, where the height of lattice point (a, b, c, d) is defined by a+b+c+d, the generation unit 210 assigns symbol “0” (or “D”) to the reference divided-hyperface when the reference face corresponds the lower side of the reference divided-hyperface and “1” (or “U”) when the reference face corresponds the upper side of the reference divided-hyperface. Next, the generation unit 210 chooses one of two divided-hyperfaces which share the reference face with the reference divided-hyperface and whose image by the projection into the predetermined hyperface in a four-dimensional space do not overlap with the image of the reference divided-hyperface by the same projection (S 1630 ). The generation unit 210 chooses the divided-hyperface in such a way that the projection of the chosen divided-hyperface imitates a part or all of the shape of the given object. In this embodiment, the image of a divided-hyperface by the projection overlaps with the image of another divided-hyperface when both of the divided-hyperface correspond to the same basic tile in the predetermined hyperface in a four-dimensional space. Next, the generation unit 210 chooses the divided-hyperface chosen in the step of S 1630 as the new reference divided-hyperface (S 1640 ). And the generation unit 210 appends a symbol “0” (or “D”) or “1” (or “U”) to the right end of the code as the symbol which corresponds to the new reference divided-hyperface (S 1645 ). Next, the generation unit 210 chooses the face of the new reference divided-face that is not the division face and not chosen in the step of S 1630 as the new reference edge (S 1650 ). The generation unit 210 executes the steps of S 1630 , S 1640 , S 1645 and S 1650 repeatedly until the shape of the given object is fully imitated by the obtained chain of divided-hyperfaces (S 1660 ). Finally, the generation unit 210 transforms the obtained chain of divided-hyperfaces into a four-dimensional shape and stores all peaks of the four-dimensional shape in the vertex-table of the administration-table-set 230 (S 1670 ). The generation unit 210 also stores the initial and terminal divided-hyperface of the chain and the code obtained by the above procedure in the shape-table of the administration-table-set 230 (S 1680 ). As explained above, the generation unit generates a chain of divided-hyperfaces by repeated executions of steps S 1630 , S 1640 , S 1645 and S 1650 . And the shape of the given object is imitated by the three-dimensional shape obtained by projecting the chain of divided-hyperfaces into the predetermined hyperface in a four-dimensional space. The generation unit 210 also generates the corresponding four-dimensional shape by assigning basic blocks which include one of the divided-hyperfaces of the chain to basic spaces. Recall that, for each point of the four-dimensional lattice, there exists a (four-dimensional) basic block whose reference vertex is given by the point and it defines a four-dimensional version of square pyramid whose peak (top vertex) is the reference vertex and the four (three-dimensional) slopes are defined by the predetermined four (three-dimensional) faces of the basic block ( 1010 d in FIG. 12 ). (In particular, the height of the pyramid is infinite.) The generation unit 210 generates a four-dimensional shape by assigning all basic blocks which are covered by a set of four-dimensional square pyramids. Thus the four-dimensional shape generated in the above procedure is specified by peaks of all four-dimensional square pyramids. And the administration unit 220 stores peaks of all four-dimensional square pyramids in the administration-table-set 230 and uses the peaks to administer the four-dimensional shape. Moreover the generation unit 210 may encode the shape of the given object by assigning either value 0 or 1 to each divided-hyperfaces of the chain in the step of S 1645 . The choice of a value reflects the choice of the corresponding divided-hyperface in the step. FIG. 18 is an outline of the structure of an amino-acid and a protein (i.e. polypeptide). The upper figure of FIG. 18 shows an outline of the structure of an amino-acid. An amino-acid has a tetrahedral (sp3) carbon atom (Cα) to which four asymmetric groups are connected: an amino group (NH2), a carboxyl group (COOH), a hydrogen atom (H) and another chemical group (denoted by R). The chemical group R varies from one amino-acid to another. The lower figure of FIG. 18 shows an outline of the structure of a protein (polypeptide). Protein is a polymer of amino-acids linked by peptide bonds. The peptide bond is formed between the amino group of the (n+1)-th amino-acid and the carboxyl group of the n-th amino-acids. The shape processing unit 120 for the second embodiment of the present invention receives a polymer such as protein as an object in a three-dimensional space and generates a chain of tiles to imitate the shape of the polymer. For example, the approximation unit 200 assigns a basic tile to each monomer (A monomer is a repeating subunit of a polymer. In this case, monomers correspond to Ns and Cs of amino-acids.). And the approximation unit 200 imitate the shape of the polymer in such a way that the position of a monomer (or N or C) corresponds to the center of the corresponding tile. When the polymer received is a protein, the approximation unit 200 assigns consecutive three basic tiles to one amino-acid of the protein. That is, the first basic tile for N of the amino group (NH2), the second tile for Cα and the third basic tile for C of the carboxyl group (COOH). FIG. 19 shows a code of a hormone (insulin, human) encoded by the shape processing unit 120 which embodies the second embodiment. The left column of the table shows the chain of amino-acids of the hormone and the right column shows the code of the chain of basic tiles which corresponds to the hormone. As you see in FIG. 19 , the hormone (insulin, human) consists of twenty-one amino-acids. In the table each amino-acids is denoted by abbreviations. For example, glycine is abbreviated to “GLY”, isoleucine to “ILE”, valine to “VAL”, glutamic acid to “GLU”, glutamine to “GLN”, cysteine to “CYS”, threonine to “THR”, serine to “SER”, leucine to “LEU”, tyrosice to “TYR” and asparagine to “ASN”. Each bond between consecutive two amino-acids of the left column is imitated by a chain of three basic tiles whose code is given in the right column. For example, as shown in the first and second low of the table, the bond between GLY and ILE is imitated by a chain of three tiles whose code is “DUD”. The chain has the same structure as chain 1250 of basic tiles in FIG. 13 . FIG. 20 shows a three-dimensional shape which imitates the shape of a hormone (insulin, human) and is generated by the shape processing unit 120 which embodies the second embodiment. The numbers on the basic tiles in FIG. 20 shows the entry number of the corresponding amino-acids in the table of FIG. 19 (numbers on the left). The shape processing unit 120 imitates the hormone given in FIG. 19 by a chain of basic tiles given in FIG. 20 and store the data of the chain. As explained above, the generation unit 210 generates a chain of basic tiles to imitates a part or all of the structure of a protein. The shape of the basic tile is a kind of tetrahedron, that is, a three-dimensional shape with four vertices. Starting from the initial tile, the chain of basic tiles is generated by connecting a basic tile with the following tile by an face one by one. FIG. 21 is an outline of the structure of a DNA molecule. A DNA molecule consists of two sugar-phosphate backbones 2000 a and 2000 b and a lot of base pairs of 2010 a and 2010 b. Two sugar-phosphate backbones 2000 a and 2000 b are a schematic drawing of the double helix of DNA. And each nucleotide base 2010 a (resp. 2010 b ) are connected to sugar-phosphate backbone 2000 a (resp. 200 b ). And each pair of 2010 a and 2010 b forms a base pair (by hydrogen bonding). FIG. 22 shows a three-dimensional shape which imitates the shape of a DNA molecule and is generated by the shape processing unit 120 which embodies the second embodiment. The structure of the three-dimensional shape is a double helix composed of two chains 2200 a and 2200 b of basic tiles. Chain 2200 a imitates sugar-phosphate backbones 2000 a , where one basic tile α corresponds to one nucleotide base 2010 a . And chain 2200 b imitates sugar-phosphate backbones 2000 b , where one basic tile β corresponds to one nucleotide base 2010 b . The shape processing unit 120 imitates the DNA molecule in FIG. 21 by a chain of basic tiles in FIG. 22 and store the chain. As explained above, the generation unit 210 generates a chain of basic tiles to imitate a part or all of the structure of a DNA molecule. The shape of the basic tile is a kind of tetrahedron, that is, a three-dimensional shape with four vertices. Starting from the initial tile, the chain of basic tiles is generated by connecting a basic tile with the following tile by a face one by one. As shown in FIG. 20 and FIG. 22 , the shape processing unit 120 can imitates a polymer using a chain of basic tiles, where a monomer or a set of monomer corresponds to a basic tile or a set of basic tiles. And the shape processing unit 120 stores the obtained chain of basic tiles. As explained above, the generation unit 210 generates a three-dimensional shape from a chain of basic tiles assigning basic blocks 300 to the corresponding basic space. The assignment is done in such a way that the chain of basic tiles corresponds to a part or all of the projection of divided-faces of the assigned basic blocks. (Recall that each basic block 300 has six divided-faces that are obtained by dividing three faces of the basic block by division lines 320 a , 320 b and 320 c .) And the generation unit 210 generates a three-dimensional shape from a chain of basic tiles in such a way that each pair of consecutive basic tiles of the chain corresponds to two divided-faces of one basic block or two consecutive basic blocks. The generated three-dimensional shape imitates the shape of the given object. As is shown above, the shape processing unit 120 according to the second embodiment transforms the shape of an object into a chain of basic tiles. And the shape processing unit 120 stores a set of peaks of a four-dimensional shape which corresponds to the chain of basic tiles as data of the shape. In this way, the shape processing unit 120 can store various kind of shapes which are imitated by a number of basic tiles. (Actually, it stores the corresponding lattice points in a four-dimensional space.) Therefore, by using the shape processing unit 120 according to the second embodiment, one can save memory of a computer when he/she stores shapes of objects. Moreover one can rotate or/and translate the shape of an object with less amount of calculation. Furthermore, the shape processing unit 120 can encode the shape of an object assigning a symbol (either “0” or “1”) to each divided-hyperface of the chain which corresponds to the chain of basic tiles obtained from the shape of the given object. In this way the shape processing unit 120 can encode any shape which is imitated by a number of basic tiles using only 1 bit for each basic tile. Thus, using the shape processing unit 120 , one needs less memory when he/she store the shape of an object. Giving a polymer to the shape processing unit 120 as an input, one obtains a chain of basic tiles which imitates the three-dimensional structure of the polymer. Lastly, the shape processing unit 120 can perform various kind of three-dimensional transformations such as rotation, translation, enlargement, reduction, composition or decomposition over some objects using the four-dimensional data in the administration-table-set 230 . The Third Embodiment of the Present Invention FIG. 23 shows hardware components of the shape processing unit 120 according to the first embodiment. CPU 1510 , ROM 1520 , RAM 1530 , network interface module 1540 and disk storage drive 1550 comprise a computer system 1500 . And computer system 1500 executes software programs to perform the shape processing due to the shape processing unit 120 . The computer system 1500 may also equipped with floppy disk drive 1560 and/or CD-ROM drive 1570 . The program which implements the shape processing unit 120 consists of an approximation module, a generation module, an administration module, a processing module, a reproduction module and an output module. These modules execute the functions of the approximation unit 200 , the generation unit 210 , the administration 220 , the processing unit 240 , the reproduction unit 250 and the output unit 260 of the first or second embodiments respectively. The administration-table-set 230 is stored in a disk storage by disk storage drive 1550 . The program or modules explained above may be stored in an external storage device. For example, one can uses optical storage devices such as DVD and PD, opt-magnetic storage devices such as MD, tape cassettes or even IC cards for the purpose. Moreover, one can use remote storage devices via network such as Internet and downloads the program to computer system 1500 . Although the present invention has been described by way of exemplary embodiment, the scope of the present invention is not limited to the foregoing embodiment. Various modifications in the foregoing embodiment may be made when the present invention defined in the appended claims is enforced. It is obvious from the definition of the appended claims that embodiments with such modifications also belong to the scope of the present invention. INDUSTRIAL APPLICABILITY It is apparent from the foregoing description that the invention provides us a shape processor and a method for representing shape that is capable of processing shapes of objects which include polymers such as proteins with less amount of calculation and also capable of storing shapes with less amount of memory. (A polymer is a large molecule made of repeating subunits linked by covalent bonds, such as polypeptide chains.)

A shape processor for processing an objective shape in a three-dimensional space while approximating, characterized by comprising an approximating section for generating a basic tile chain, i.e., a chain of basic tiles approximating the structure of the objective shape partially or entirely, by connecting the basic tiles of predetermined three dimensional shape having substantially tetrahedral shape including four vertexes sequentially starting with a starting point basic tile on the face of the basic tile.

[0001] The present invention relates to vaccine formulations comprising papilloma virus proteins, either as fusion proteins, truncated proteins, or truncated fusion proteins. The invention further embraces methods for producing capsomeres of the formulations, as well as prophylactic and therapeutic methods for their use. BACKGROUND [0002] Infections with certain high-risk strains of genital papilloma viruses in humans (HPV) —for example. HPV 16, 18, or 45—are believed to be the main risk factor for the formation of malignant tumors of the anogenital tract. Of the possible malignancies, cervical carcinoma is by far the most frequent: according to an estimate by the World Health Organization (WHO). almost 500.000 new cases of the disease occur annually. Because of the frequency with which this pathology occurs. the connection between HPV infection and cervical carcinoma has been extensively examined. leading to numerous generalizations. [0003] For example. precursor lesions of cervical intraepithelial neoplasia (CIN) are known to be caused by papilloma virus infections [Crum, New Eng. J. Med. 310:880-883 (1984)]. DNA from the genomes of certain HPV types. including for example. strains 16, 18, 33, 35, and 45, have been detected in more than 95% of tumor biopsies from patients with this disorder, as well as in primary cell lines cultured from the tumors. Approximately 50 to 70% of the biopsied CIN tumor cells have been found to include DNA derived only from HPV 16. [0004] The protein products of the HPV 16 and HPV 18 early genes E6 and E7 have been detected in cervical carcinoma cell lines as well as in human keratinocytes transformed in vitro [Wettstein, et al., in PAPILLOMA VIRUSES AND HUMAN CANCER, Pfister (Ed.),CRC Press: Boca Paton, Fla. 1990 pp 155-179] and a significant percentage of patients with cervical carcinoma have anti-E6 or anti-E7 antibodies. The E6 and E7 proteins have been shown to participate in induction of cellular DNA synthesis in human cells. transformation of human keratinocytes and other cell types, and tumor formation in transgenic mice [Arbelt, et al., J. Virol., 68:4358-4364 (1994): Auewarakul, et al., Mol. Cell. Biol. 14:8250-8258 (1994); Barbosa. et al., J. Virol. 65:292-298 (1991); Kaur, et al., J. Gen. Virol. 70:1261-1266 (1989): Schlegel, et al., EMBO J., 7:3181-3187 (1988)]. The constitutive expression of the E6/E7 proteins appears to be necessary to maintain the transformed condition of HPV-positive tumors. [0005] Despite the capacity of some HPV strains to induce neoplastic phenotypes in vivo and in vitro. still other HPV types cause benign genital warts such as condylomata acuminata and are only rarely associated with malignant tumors [Ikenberg. In Gross, et al., (eds.) GENITAL PAPILLOMAVIRUS INFECTIONS. Springer Verlag: Berlin, pp., 87-112]. Low risk strains of this type include. for example, HPV 6 and 11. [0006] Most often. genital papilloma viruses are transmitted between humans during intercourse which in many instances leads to persistent infection in the anogenital mucous membrane. While this observation suggests that either the primary infection induces an inadequate immune response or that the virus has developed the ability to avoid immune surveillance, other observations suggest that the immune system is active during primary manifestation as well as during malignant progression of papilloma virus infections [Altmann et al. in VIRUSES AND CANCER, Minson et al., (eds.) Cambridge University Press, (1994) pp. 71-80]. [0007] For example, the clinical manifestation of primary infection by rabbit and bovine papilloma virus can be prevented by vaccination with wart extracts or viral structural proteins [Altmann, et al., supra; Campo, Curr. Top. In Microbiol and Immunol. 186:255-266 (1994); Yindle and Frazer, Curr. Top. In Microbiol. and Immunol, 186;217-253 (1994)]. Rodents previously vaccinated with vaccinia recombinants encoding HPV 16 early proteins E6 or E7, or with synthetic E6 or E7 peptides, are similarly protected from tumor formation after inoculation of HPV 16 transformed autologous cells [Altman, et al., supra; Campo, et al., supra; Yindle and Frazer, et al. supra]. Regression of warts can be induced by the transfer of lymphocytes from regressor animals following infection by animal papilloma viruses. Finally, in immunosuppressed patients, such as, for example, recipients of organ transplants or individuals infected with HIV, the incidence of genital warts. CIN. and anogenital cancer is elevated. [0008] To date, no HPV vaccinations have been described which comprise human papilloma virus late L1 protein in the form of capsomeres which are suitable both for prophylactic and therapeutic purposes. Since the L1 protein is not present in malignant genital lesions, vaccination with L1 protein does not have any therapeutic potential for these patients. Construction of chimeric proteins. comprising amino acid residues from L1 protein and, for example E6 or E7 protein. which give rise to chimeric capsomeres, combines prophylactic and therapeutic functions of a vaccine. A method for high level production of chimeric capsomeres would therefore be particularly desirable. in view of the possible advantages offered by such a vaccine for prophylactic and therapeutic intervention. [0009] Thus there exists a need in the art to provide vaccine formulations which can prevent or treat HPV infection. Methods to produce vaccine formulations which overcome problems known in the art to be associated with recombinant HPV protein expression and purification would manifestly be useful to treat the population of individuals already infected with HPV as well as useful to immunize the population of individuals susceptible to HPV infection. SUMMARY OF THE INVENTION [0010] The present invention provides therapeutic and prophylactic vaccine formulations comprising chimeric human papilloma capsomeres. The invention also provides therapeutic methods for treating patients infected with an HPV as well as prophylactic methods for preventing HPV infection in a susceptible individual. Methods for production and purification of capsomeres and proteins of the invention are also contemplated. [0011] In one aspect of the invention, prophylactic vaccinations for prevention of HPV infection are considered which incorporate the structural proteins L1 and L2 of the papilloma virus. Development of a vaccine of this type faces significant obstacles because papilloma viruses cannot be propagated to adequate titers in cell cultures or other experimental systems to provide the viral proteins in sufficient quantity for economical vaccine production. Moreover. recombinant methodologies to express the proteins are not always straightforward and often results in low protein yield. Recently. virus-like particles (VLPs). similar in make up to viral capsid structures. have been described which are formed in Sf-9 insect cells upon expression of the viral proteins L1 and L2 (or L1 on its own) using recombinant vaccinia or baculovirus. Purification of the VLPs can be achieved very simply by means of centrifugation in CsCl or sucrose gradients [Kimbauer. et al.. Proc. Natl. Acad. Sci. ( USA ), 99:12180-12814 (1992): Kimbaurer. et al., J. Virol. 67:6929-6936 (1994); Proso, et al., J. Virol. 6714:1936-1944 (1992): Sasagawa. et al., Virology 2016:126-195 (1995): Volpers, et al., J. Virol. 69:3258-3264 (1995); Zhou, et al., J. Gen. Virol. 74:762-769 (1993): Zhou, et al., Virology 185:251-257 (1991)]. WO 93/02184 describes a method in which papilloma virus-like particles (VLPs) are used for diagnostic applications or as a vaccine against infections caused by the papilloma virus. WO 94/00152 describes recombinant production of L1 protein which mimics the conformational neutralizing epitope on human and animal papilloma virions. [0012] In another aspect of the invention, therapeutic vaccinations are provided to relieve complications of, for example, cervical carcinoma or precursor lesions resulting from papilloma virus infection, and thus represent an alternative to prophylactic intervention. Vaccinations of this type may comprise early papilloma virus proteins, principally E6 or E7. which are expressed in the persistently infected cells. It is assumed that. following administration of a vaccination of this type, cytotoxic T-cells might be activated against persistently infected cells in genital lesions. The target population for therapeutic intervention is patients with HPV-associated pre-malignant or malignant genital lesions. PCT patent application WO 93/20844 discloses that the early protein E7 and antigenic fragments thereof of the papilloma virus from HPV or BPV is therapeutically effective in the regression. but not in the prevention. of papilloma virus tumors in mammals. While early HPV proteins have been produced by recombinant expression in E. coli or suitable eukaryotic cell types. purification of the recombinant proteins has proven difficult due to inherent low solubility and complex purification procedures which generally require a combination of steps, including ion exchange chromatography, gel filtration and affinity chromatography. [0013] According to the present invention, vaccine formulations comprising papilloma virus capsomeres are provided which comprise either: (i) a first protein that is an intact viral protein expressed as a fusion protein comprised in part of amino acid residues from a second protein; (ii) a truncated viral protein; (iii) a truncated viral protein expressed as a fusion protein comprised in part of amino acid residues from a second protein, or (iv) some combination of the three types of proteins. According to the invention, vaccine formulations are provided comprising capsomeres of bovine papilloma virus (BPV) and human papilloma virus. Preferred bovine virus capsomeres comprise protein from bovine papilloma virus type I. Preferred human virus capsomeres comprise proteins from any one of human papilloma virus strains HPV6, HPV11, HPV16, HPV18, HPV33, HPV35, and HPV45. The most preferred vaccine formulations comprise capsomeres comprising proteins from HPV16. [0014] In one aspect, capsomere vaccine formulations of the invention comprise a first intact viral protein expressed as a fusion protein with additional amino acid residues from a second protein. Preferred intact viral proteins are the structural papilloma viral proteins L1 and L2. Capsomeres comprised of intact viral protein fusions may be produced using the L1 and L2 proteins together or the L1 protein alone. Preferred capsomeres are made up entirely of L1 fusion proteins, the amino acid sequence of which is set out in SEQ ID NO: 2 and encoded by the polynucleotide sequence of SEQ ID NO: 1. Amino acids of the second protein can be derived from numerous sources (including amino acid residues from the first protein) as long as the addition of the second protein amino acid residues to the first protein permits formation of capsomeres. Preferably, addition of the second protein amino acid residues inhibits the ability of the intact viral protein to form virus-like particle structures; most preferably, the second protein amino acid residues promote capsomere formation. In one embodiment of the invention, the second protein may be any human tumor antigen. viral antigen. or bacterial antigen which is important in stimulating an immune response in neoplastic or infectious disease states. In a preferred embodiment. the second protein is also a papilloma virus protein. It also preferred that the second protein be the expression product of papilloma virus early gene. It is also preferred, however, that the second protein be selected from group of E1, E2, E3, E4, E5, E6, and E7 -- early gene products encoded in the genome of papilloma virus strains HVP6. HPV11, HPV18, HPV33, HPV35, or HPV 45. It is most preferred that the second protein be encoded by the HPV16 E7 gene, the open reading frame of which is set out in SEQ ID NO: 3. Capsomeres assembled from fusion protein subunits are referred to herein as chimeric capsomeres. In one embodiment, the vaccine formulation of the invention is comprised of chimeric capsomeres wherein L1 protein amino acid residues make up approximately 50 to 99% of the total fusion protein amino acid residues. In another embodiment, L1 amino acid residues make up approximately 60 to 90% of the total fusion protein amino acid residues; in a particularly preferred embodiment, L1 amino acids comprise approximately 80% of the fusion protein amino acid residues. [0015] In another aspect of the invention, capsomere vaccine formulations are provided that are comprised of truncated viral proteins having a deletion of one or more amino acid residues necessary for formation of a virus-like particle. It is preferred that the amino acid deletion not inhibit formation of capsomeres by the truncated protein, and it is most preferred that the deletion favor capsomere formation. Preferred vaccine formulations of this type include capsomeres comprised of truncated L1 with or without L2 viral proteins. Particularly preferred capsomeres are comprised of truncated L1 proteins. Truncated proteins contemplated by the invention include those having one or more amino acid residues deleted from the carboxy terminus of the protein, or one or more amino acid residues deleted from the amino terminus of the protein, or one or more amino acid residues deleted from an internal region (i.e., not from either terminus) of the protein. Preferred capsomere vaccine formulations are comprised of proteins truncated at the carboxy terminus. In formulations including L1 protein derived from HPV16, it is preferred that from 1 to 34 carboxy terminal amino acid residues are deleted. Relatively shorter deletions are also contemplated which offer the advantage of minor modification of the antigenic properties of the L1 proteins and the capsomeres formed thereof. It is most preferred, however, that 34 amino acid residues be deleted from the L1 sequence, corresponding to amino acids 472 to 505 in HPV16 set out in SEQ ID NO: 2, and encoded by the polynucleotide sequence corresponding to nucleotides 1414 to 1516 in the human HPV16 L1 coding sequence set out in SEQ ID NO: 1. [0016] When a capsomere vaccine formulation is made up of proteins bearing an internal deletion, it is preferred that the deleted amino acid sequence comprise the nuclear localization region of the protein. In the L1 protein of HPV 16, the nuclear localization signal is found from about amino acid residue 499 to about amino acid residue 505. Following expression of L1 proteins wherein the NLS has been deleted, assembly of capsomere structures occurs in the cytoplasm of the host cell. Consequently. purification of the capsomeres is possible from the cytoplasm instead of from the nucleus where intact L1 proteins assemble into capsomeres. Capsomeres which result from assembly of truncated proteins wherein additional amino acid sequences do not replace the deleted protein sequences are necessarily not chimeric in nature. [0017] In still another aspect of the invention, capsomere vaccine formulations are provided comprising truncated viral protein expressed as a fusion protein adjacent amino acid residues from a second protein. Preferred truncated viral proteins of the invention are the structural papilloma viral proteins L1 and L2. Capsomeres comprised of truncated viral protein fusions may be produced using L1 and L2 protein components together or L1 protein alone. Preferred capsomeres are those comprised of L1 protein amino acid residues. Truncated viral protein components of the fusion proteins include those having one or more amino acid residues deleted from the carboxy terminus of the protein, or one or more amino acid residues deleted from the amino terminus of the protein, or one or more amino acid residues deleted from an internal region (i.e., not from either terminus) of the protein. Preferred capsomere vaccine formulations are comprised of proteins truncated at the carboxy terminus. In those formulations including L1 protein derived from HPV16, it is preferred that from 1 to 34 carboxy terminal amino acid residues are deleted. Relatively shorter deletions are also contemplated that offer the advantage of minor modification of the antigenic properties of the L1 protein component of the fusion protein and the capsomeres formed thereof. It is most preferred, however, that 34 amino acid residues be deleted from the L1 sequence, corresponding to amino acids 472 to 505 in HPV16 set out in SEQ ID NO: 2, and encoded by the polynucleotide sequence corresponding to nucleotides 1414 to 1516 in the human HPV16 L1 coding sequence set out in SEQ ID NO: 1. When the vaccine formulation is comprised of capsomeres made up of proteins bearing an internal deletion, it is preferred that the deleted amino acid sequence comprise the nuclear localization region, or sequence. of the protein. [0018] Amino acids of the second protein can be derived from numerous sources as long as the addition of the second protein amino acid residues to the first protein permits formation of capsomeres. Preferably, addition of the second protein amino acid residues promotes or favors capsomere formation. Amino acid residues of the second protein can be derived from numerous sources. including amino acid residues from the first protein. In a preferred embodiment. the second protein is also a papilloma virus protein. It also preferred that the second protein be the expression product of papilloma virus early gene. It is most preferred, however, that the second protein be selected from group of early gene products encoding by papilloma virus E1. E2, E3, E4, E5, E6, and E7 genes. In one embodiment. the vaccine formulation of the invention is comprised of chimeric capsomeres wherein L1 protein amino acid residues make up approximately 50 to 99% of the total fusion protein amino acid residues. In another embodiment, L1 amino acid residues make up approximately 60 to 90% of the total fusion protein amino acid residues; in a particularly preferred embodiment, L1 amino acids comprise approximately 80% of the fusion protein amino acid residues. [0019] In a preferred embodiment of the invention, proteins of the vaccine formulations are produced by recombinant methodologies, but in formulations comprising intact viral protein, the proteins may be isolated from natural sources. Intact proteins isolated from natural sources may be modified in vitro to include additional amino acid residues to provide a fusion protein of the invention using covalent modification techniques well known and routinely practiced in the art. Similarly, in formulations comprising truncated viral proteins. the proteins may be isolated from natural sources as intact proteins and hydrolyzed in vitro using chemical hydrolysis or enzymatic digestion with any of a number of site-specific or general proteases. the truncated protein subsequently modified to include additional amino acid resides as described above to provide a truncated fusion protein of the invention. [0020] In producing capsomeres. recombinant molecular biology techniques can be utilized to produce DNA encoding either the desired intact protein. the truncated protein. or the truncated fusion protein. Recombinant methodologies required to produce a DNA encoding a desired protein are well known and routinely practiced in the art. Laboratory manuals. for example Sambrook. et al.. (eds.), MOLECULAR CLONING: A LABORATORY MANUAL. Cold Spring Harbor Press: Cold Spring Harbor, N.Y. (1989) and Ausebel et al., (eds.). PROTOCOLS IN MOLECULAR BIOLOGY. John Wiley & Sons. Inc. (1994-1997), describe in detail techniques necessary to carry out the required DNA manipulations. For large-scale production of chimeric capsomeres, protein expression can be carried out using either viral or eukaryotic vectors. Preferable vectors include any of the well known prokaryotic expression vectors, recombinant baculoviruses, COS cell specific vectors, vaccinia recombinants, or yeast-specific expression constructs. When recombinant proteins are used to provide capsomeres of the invention, the proteins may first be isolated from the host cell of its expression and thereafter incubated under conditions which permit self-assembly to provide capsomeres. Alternatively, the proteins may be expressed under conditions wherein capsomeres are formed in the host cell. [0021] The invention also contemplates processes for producing capsomeres of the vaccine formulations. In one method, L1 proteins are expressed from DNA encoding six additional histidines at the carboxy terminus of the L1 protein coding sequence. L1 proteins expressed with additional histidines (His L1 proteins) are most preferably expressed in E. coli and the His L1 proteins can be purified using nickel affinity chromatography. His L1 proteins in cell lysate are suspended in a denaturation buffer. for example. 6 M guanidine hydrochloride or a buffer of equivalent denaturing capacity. and then subjected to nickel chromatography. Protein eluted from the nickel chromatography step is renatured. for example in 150 mM NaCl. 1 mM CaCl 2 , 0.01% Triton-X 100, 10 mM HEPES (N-2-hydroxyethyl piperazine-N′-2 ethane sulfonic acid), pH 7.4. According to a preferred method of the invention, assembly of capsomeres takes place after dialysis of the purified proteins, preferably after dialysis against 150 mM NaCl. 25 mM Ca 2+ , 10% DMSO (dimethyl sulfoxide). 0.1% Triton-X 100. 10 mM Tris [tris-(hydroxymethyl) amino-methane] acetic acid with a pH value of 5.0. [0022] Formation of capsomeres can be monitored by electron microscopy, and, in instances wherein capsomeres are comprised of fusion proteins, the presence of various protein components in the assembled capsomere can be confirmed by Western blot analysis using specific antisera. [0023] According to the present invention. methods are provided for therapeutic treatment of individuals infected with HPV comprising the step of administering to a patient in need thereof an amount of a vaccine formulation of the invention effective to reduce the level of HPV infection. The invention also provide methods for prophylactic treatment of individuals susceptible to HPV infection comprising the step of administering to an individual susceptible to HPV infection an amount of a vaccine formulation of the invention effective to prevent HPV infection. While infected individuals can be easily identified using standard diagnostic techniques, susceptible individuals may be identified, for example, as those engaged in sexual relations with an infected individual. However, due to the high frequency of HPV infection, all sexually active persons are susceptible to papilloma virus infection. [0024] Administration of a vaccine formulation can include one or more additional components such as pharmaceutically acceptable carriers, diluents. adjuvants. and/or buffers. Vaccines may be administered at a single time or at multiple times. Vaccine formulation of the invention may be delivered by various routes including. for example, oral, intravenous, intramuscular. nasal. rectal. transdermal. vaginal, subcutaneous. and intraperitoneal administration. [0025] Vaccine formulations of the invention offer numerous advantages when compared to conventional vaccine preparations. As part of a therapeutic vaccination. capsomeres can promote elimination of persistently infected cells in. for example. patients with CIN or cervical carcinoma. Additionally. therapeutic vaccinations of this type can also serve a prophylactic purpose in protecting patients with CIN lesions from re-infection. As an additional advantage. capsomeres can escape neutralization by pre-existing anticapsid antibodies and thereby posses longer circulating half-life as compared to chimeric virus-like particles. [0026] Vaccine formulations comprising chimeric capsomeres can provide the additional advantage of increased antigenicity of both protein components of the fusion protein from which the capsomere is formed. For example, in a VLP, protein components of the underlying capsomere may be buried in the overall structure as a result of internalized positioning within the VLP itself. Similarly, epitopes of the protein components may be sterically obstructed as a result of capsomere-to-capsomere contact, and therefore unaccessible for eliciting an immune response. Preliminary results using L1/E7 fusion proteins to produce VLPs support this position in that no antibody response was detected against the E7 component. This observation is consistent with previous results which indicate that the carboxy terminal region of L1 forms inter-pentameric arm structures that allow assembly of capsomeres into capsids [Garcia, et al., J. Virol. 71: 2988-2995 (1997)]. Presumably in a chimeric capsomere structure, both protein components of the fusion protein substructure are accessible to evoke an immune response. Capsomere vaccines would therefore offer the additional advantage of increased antigenicity against any protein component, including. for example. neutralizing epitopes from other virus proteins, expressed as a fusion with L1 amino acid sequences. DETAILED DESCRIPTION OF THE INVENTION [0027] The present invention is illustrated by the following examples. Example 1 describes construction of expression vectors to produce fusion. or chimeric. viral proteins. Example 2 relates to generation of recombinant baculoviruses for expression of viral proteins. Example 3 addresses purification of capsomeres. Example 4 describes an immunization protocol for production of antisera and monoclonal antibodies. Example 5 provides a peptide ELISA to quantitate capsomere formation. Example 6 describes an antigen capture ELISA to quantitate capsomere formation. Example 7 provides a hemagglutinin assay to assay for the induction of neutralizing antibodies. EXAMPLE 1 Construction of Chimeric L1 Genes [0028] DNA,encoding the HPV 16 L1 open reading frame was excised from plasmid 16-114/k-L1/L2-pSynxtVI − [Kimbauer et al., J. Virol. 67:6929-6936 (1994)] using BglII and the resulting fragment subcloned into pUC19 (New England Biolabs. Beverly, Mass.) previously linearized at the unique BamHI restriction site. Two basic expression constructs were first generated to permit subsequent insertion of DNA to allow fusion protein expression. One construct encoded HPV 16 L1Δ310 having a nine amino acid deletion: the deleted region was known to show low level homology with all other papilloma virus L1 proteins. The second construct, HPV 16 L1ΔC, encoded a protein having a 34 amino acid deletion of the carboxy terminal L1 residues. Other constructs include an EcoRV restriction site at the position of the deletion for facilitated insertion of DNA encoding other protein sequences. Addition of the EcoRV site encodes two non-L1 protein amino acids, aspartate and isoleucine. A. Generation of an HPV 16 L1Δ310 Expression Construct [0029] Two primers (SEQ ID NOs: 5 and 6) were designed to amplify the pUC19 vector and the complete HPV 16 L1 coding sequence, except nucleotides 916 through 942 in SEQ ID NO: 1. Primers were synthesized to also introduce a unique EcoRV restriction site (underlined in SEQ ID NOs: 5 and 6) at the termini of the amplification product. CCCC GATATC GCCTTTAATGTATAAATCGTCTGG SEQ ID NO: 5 CCCC GATATC TCAAATTATTTITCCTACACCTAGTG SEQ ID NO: 6 [0030] The resulting PCR product was digested with EcoRV to provide complementary ends and the digestion product circularized by ligation. Ligated DNA was transformed into E. coli using standard techniques and plasmids from resulting colonies were screened for the presence of an EcoRV restriction site. One clone designated HPV 16 L1Δ310 was identified as having the appropriate twenty-seven nucleotide deletion and this construct was used to insert DNA fragments encoding other HPV 16 proteins at the EcoRV site as discussed below. B. Generation of an HPV 16 L1ΔC Expression Constructs [0031] Two primers (SEQ ID NOs: 7 and 8) were designed complementary to the HPV 16 L1 open reading frame such that the primers abutted each other to permit amplification in reverse directions on the template DNA comprising HPV 16 L1-encoding sequences in pUC19 described above. AAA GATATC TTGTAGTAAAAATTTGCGTCCTAAAGGAAAC SEQ ID NO: 7 AAA GATATC TAATCTACCTCTACAACTGCTAAACGCAAAAAACG SEQ ID NO: 8 [0032] Each primer introduced an EcoRV restriction site at the terminus of the amplification product. In the downstream primer (SEQ ID NO: 8), the EcoRV site was followed by a TAA translational stop codon positioned such that the amplification product. upon ligation of the EcoRV ends to circularize, would include deletion of the 34 carboxy terminal L1 amino acids. PCR was performed to amplify the partial L1 open reading frame and the complete vector. The amplification product was cleaved with EcoRV, circularized with T4 DNA ligase. and transformed into E. coli DH5 α cells. Plasmids from viable clones were analyzed for the presence of an EcoRV site which would linearize the plasmid. One positive construct designated pUCHPV16L1ΔC was identified and used to insert DNA from other HPV 16 proteins utilizing the EcoRV site. C. Insertion of DNA fragments into HPV 16 L1Δ310 and HPV16L1ΔC [0033] DNA fragments of HPV 16 E7 encoding amino acids 1-50, 1-60. 1-98, 25-75, 40-98, 50-98 in SEQ ID NO: 4 were amplified using primers that introduced terminal 5′ EcoRV restriction sites in order to facilitate insertion of the fragment into either HPV 16 L1Δ310 and HPV16L1ΔC modified sequence. In the various amplification reactions, primer E7.1 (SEQ ID NO: 9) was used in combination with primer E7.2 (SEQ ID NO: 10) to generate a DNA fragment encoding E7 amino acids 1-50: with primer E7.3 (SEQ ID NO: 11) generate a DNA fragment encoding E7 amino acids 1-60: or with primer E7.4 (SEQ ID NO: 12) generate a DNA fragment encoding E7 amino acids 1-98. In other amplification reactions. primer pairs E7.5 (SEQ ID NO: 13) and E7.6 (SEQ ID NO: 14) were used to amplify a DNA fragment encoding E7 amino acids 25-75: E7.7 (SEQ ID NO: 15) and E7.4 (SEQ ID NO: 12) were used to amplify a DNA fragment encoding E7 amino acids 40-98; and E7.8 (SEQ ID NO: 16) and E7.4 (SEQ ID NO: 12) were used to amplify a DNA fragment encoding E7 amino acids 50-98. Primer E7.1 SEQ ID NO: 9 AAAA GATATC ATGCATGGAGATACACCTACATTGC Primer E7.2 SEQ ID NO: 10 TTTT GATATC GGCTCTGTCCGGTTCTGCTTGTCC Primer E7.3 SEQ ID NO: 11 TTTT GATATC CTTGCAACAAAAGGTTACAATATTGTAA TGGGCC Primer E7.4 SEQ ID NO: 12 AAAA GATATC TGGTTTCTGAGAACAGATGGGGCAC Primer E7.5 SEQ ID NO: 13 TTTT GATATC GATTATGAGCAATTAAATGACAGCTCAG Primer E7.6 SEQ ID NO: 14 TTTT GATATC GTCTACGTGTGTGCTTTGTACGCAC Primer E7.7 SEQ ID NO: 15 TTTATC GATATC GGTCCAGCTGGACAAGCAGAACCGGAC Primer E7.8 SEQ ID NO: 16 TTTT GATATC GATGCCCATTACAATATTGTAACCTTTTG [0034] Similarly. nucleotides from DNA encoding the influenza matrix protein (SEQ ID NO: 17) was amplified using the primer pair set out in SEQ ID NOs: 19 and 20. Both primers introduced an EcoRV restriction site in the amplification product. TTTT GATATC GATATGGAATGGCTAAAGACAAGACCAATC SEQ ID NO: 19 TTTT GATATC GTTGTTTGGATCCCCATTCCCATTG SEQ ID NO: 20 [0035] PCR products from each amplification reaction were cleaved with EcoRV and inserted into the EcoRV site of either the HPV 16 L1Δ310 and HPV16L1ΔC sequences previously linearized with the same enzyme. In order to determine the orientation of inserts in plasmids encoding E7 amino acids 25-75 and 50-98 and plasmid including influenza matrix protein, ClaI digestion was employed, taking advantage of a restriction site overlapping the newly created EcoRV restriction site ( GATATC GAT) and included in the upstream primer. For the three expression constructs including the initiating methionine of HPV16 E7, insert orientation was determined utilizing a NslI restriction site within the E7 coding region. [0036] Once expression constructs having appropriate inserts were identified, the protein coding region for both L1 and inserted amino acids was excised as a unit using restriction enzymes XbaI and SmaI and the isolated DNA ligated into plasmid pVL1393 (Invitrogen) to generate recombinant baculoviruses. D. Elimination of EcoRV Restriction Sites in Expression Constructs [0037] The HPV 16 L1 ΔC sequence includes DNA from the EcoRV site that results in translation of amino acids not normally found in wild-type L1 polypeptides. Thus. a series of expression constructions was designed in which the artificial EcoRv site was eliminated. The L1 sequence for this series of expression constructs was designated HPV 16L1ΔC*. [0038] To generate an expression construct containing the HPV 16L1ΔC sequence. two PCR reactions were performed to amplify two overlapping fragments from the pUC-HPV16 L1ΔC encoding E7 amino acids 1-50. The resulting DNA fragments overlapped at the position of the L1/E7 boundary but did not contain the two EcoRV restriction sites. Fragment 1 was generated using primers P1 (SEQ ID NO: 21) and P2 (SEQ ID NO: 22) and fragment 2 using primers P3 (SEQ ID NO: 23) and P4 (SEQ ID NO: 24). Primer P1 SEQ ID NO: 21 GTTATGACATACATACATTCTATG Primer P2 SEQ ID NO: 22 CCATGCATTCCTGCTTGTAGTAAAAATTTGCGTCC Primer P3 SEQ ID NO: 23 CTACAAGCAGGAATGCATGGAGATACACC Primer P4 SEQ ID NO: 24 CATCTGAAGCTTAGTAATGGGCTCTGTCCGGTTCTG [0039] Following the first two amplification reactions, the two purified products were used as templates in another PCR reaction using primers P1 and P4 only. The resulting amplification product was digested with enzymes EcoNI and HindIII inserted into the HPV 16L1ΔC expression construct described above following digestion with the same enzymes. The resulting expression construct differed from the original HPV16L1ΔC construct with DNA encoding L1 and E7 amino acids 1-50 by loss of the two internal EcoRV restriction sites. The first EcoRV site was replaced by DNA encoding native L1 alanine and glycine amino acids in this position and the second was replaced by a translational stop signal. In addition, the expression construct. designated HPV 16 L1ΔC* E7 1-52, contained the first 52 amino acids of HPV 16 E7 as a result of using primer P4 which also encodes E7 amino acids residues histidine at position 51 and tyrosine at position 52. HPV 16 L1ΔC* E7 1-52 was then used to generate additional HPV 16 L1ΔC expression constructs further including DNA encoding E7 amino acids 1-55 using primer P1 (SEQ ID NO: 21) in combination with primer P5 (SEQ ID NO: 25), E7 amino acids 1-60 with primer pair P1 and P6 (SEQ ID NO: 26). and E7 amino acids 1-65 with primer pair P1 and P7 (SEQ ID NO: 27). The additional animo acid-encoding DNA sequences in the amplification products arose from design of the primers to include additional nucleotides for the desired amino acids. Primer P5 SEQ ID NO: 25 CATCTGAAGCTTAACAATATTGTAATGGGCTCTGTCCG Primer P6 SEQ ID NO: 26 CATCTGAAGCTTACTGTCAACAAAAGGTTA- CAATATTGTAATGGGCTCTGTCCG Primer P7 SEQ ID NO: 27 CATCTGAAGCTTAAAGCGTAGAGTCACACTTGCAAC- AAAAGGTTACAATATTGTAATGGGCTCTGTCCG Similarly. HPV 16 L1ΔC* E7 1-70 was generated using template DNA encoding HPV 16 L1ΔC* E7 1-66 and the primer pair P1 and P8 (SEQ ID NO: 28). Primer P8 SEQ ID NO: 28 CATCTGAAGCTTATTGTACGCACAAC- CGAAGCGTAGAGTCACACTTG [0040] Similarly, HPV 16 L1ΔC* E7 1-70 was generated using template DNA encoding HPV 16 L1ΔC* E7 1-66 and the primer pair P1 and P8 (SEQ ID NO: 28). [0041] Following each PCR reaction. the amplification products were digested with EcoNI and HindIII and inserted into HPV16L1ΔC previously digested with the same enzymes. Sequences of each constructs were determined using an Applied Biosystems Prism 377 sequencing instrument with fluorescent chain terminating dideoxynucleotides [Prober et al., Science 238:336-341 (1987)]. EXAMPLE 2 Generation of Recombinant Baculoviruses [0042] [0042] Spodoptera frugiperda (Sf9) cells were grown in suspension or monolayer cultures at 27° in TNMFH medium (Sigma) supplemented with 10% fetal calf serum and 2 mM glutamine. For HPV 16 L1-based recombinant baculovirus construction, Sf9 cells were transfected with 10 μg of transfer plasmid together with 2 μg of linearized Baculo-Gold DNA (PharMingen, San Diego, Calif.). Recombinant viruses were purified by according to manufacturers suggested protocol. [0043] To test for expression of HPV 16 L1 protein, 10 5 Sf9 cells were infected with baculovirus recombinant at a multiplicity of infection (m.o.i) of 5 to 10. After incubation for three to four days at 28° C., media was removed and cells were washed with PBS. The cells were lysed in SDS sample buffer and analyzed by SDS-PAGE and Western blotting using anti-HPV16 L1 and anti-HPV16 E7 antibodies. [0044] In order to determine which of the chimeric L1 protein expression constructs would preferentially produce capsomeres, extracts from transfected cells were subjected to gradient centrifugation. Fractions obtained from the gradient were analyzed for L1 protein content by Western blotting and for VLP formation by electron microscopy. The results are shown in Table 1. [0045] The intact HPV L1 protein. as well as the expression products HPV 16 L1Δ310 and HPV 16 L1ΔC. each were shown to produce capsomeres and virus-like particles in equal proportions. When E7 coding sequences were inserted into the HPV 16 L1Δ310 vector, only fusion proteins including E7 amino acids 1 to 50 produced gave rise to detectable capsomere formation. [0046] When E7 encoding DNA was inserted into the HPV 16 L1ΔC vector, all fusion proteins were found to produce capsomeres; chimeric proteins including E7 amino acid residues 40-98 produced the highest level of exclusively capsomere structures. Chimeric proteins including E7 amino acids 1-98 and 25-75 both produced predominantly capsomeres, even thorough virus-like particle formation was also observed. The chimeric protein including E7 amino acids 1-60 resulted in nearly equal levels of capsomere and virus-like particle production. [0047] When E7 sequences were inserted into the HPV 16 L 1Δ*C vector, all fusion proteins were shown to produce capsomeres. Insertion of DNA encoding E 7 residues 1-52, 1-55, and 1-60 produced the highest level of capsomeres, but equal levels of virus-like particle production were observed. While insertion of DNA encoding E7 DNA for residues 1-65, 1-70, 25-75, 40-98, and 1-98 resulted in comparatively lower levels or undetectable levels of capsid, capsomeres were produced in high quantities. TABLE 1 Capsomeree and Capsid Forming Capacity of Chimeric HPV L1 Proteins L1 Expression Capsomere Capsid Construct Insert Yield Yield HVP 16 L1 None + + + + + + + + + + HPV 16 L1Δ310 None + + + + + HPV 16 L1ΔC None + + + + + + + + HPV 16 L1Δ310 E7 1-98 − − HPV 16 L1Δ310 E7 1-50 + + − HPV 16 L1Δ310 E7 25-75 − − HPV 16 L1Δ310 E7 50-98 − − HPV 16 L1ΔC E7 1-98 + + + + HPV 16 L1ΔC E7 25-75 + + + + HPV 16 L1ΔC E7 50-98 + + HPV 16 L1ΔC E7 1-60 + + + + + + + + + + HPV 16 L1ΔC E7 40-98 + + + + − HPV 16 L1ΔC Influenza + + + + HPV 16 L1Δ*C E7 1-52 + + + + + + + + + + HPV 16 L1Δ*C E7 1-55 + + + + + + + + + + HPV 16 L1Δ*C E7 1-60 + + + + + + + HPV 16 L1Δ*C E7 1-65 + + − HPV 16 L1Δ*C E7 1-70 + + − EXAMPLE 3 Purification of Capsomeres [0048] Trichopulsia ni (TN) High Five cells were grown to a density of approximately 2×10 6 cells/ml in Ex-Cell 405 serum-free medium (JRH Biosciences). Approximately 2×10 8 cells were pelleted by centrifugation at 1000×g for 15 minutes. resuspended in 20 ml of medium, and infected with recombinant baculoviruses at m.o.i of 2 to 5 for 1 hour at room temperature. After addition of 200 ml medium. cells were plated and incubated for 3 to 4 days at 27° C. Following incubation. cells were harvested, pelleted, and resuspended in 10 ml of extraction buffer. [0049] The following steps were performed at 4° C. Cells were sonicated for 45 seconds at 60 watts and the resulting cell lysate was centrifuged at 10,000 rpm in a Sorval SS34 rotor. The supernatant was removed and retained while the resulting pellet was resuspended in 6 ml of extraction buffer. sonicated for an additional 3 seconds at 60 watts. and centrifuged again. The two supernatants were combined. layered onto a two-step gradient containing 14 ml of 40% sucrose on top of 8 ml of CsCl solution (4.6 g CsCl per 8 ml in extraction buffer), and centrifuged in a Sorval AH629 swinging bucket rotor for 2 hours at 27.000 rpm at 10° C. The interface region between the CsCl and the sucrose along with the CsCl complete layer were collected into 13.4 ml Quickseal tubes (Beckman) and extraction buffer added to adjust the volume 13.4 ml. Samples were centrifuged overnight at 50.000 rpm at 20° C. in a Beckman 70 TI rotor. Gradients were fractionated (1 ml per fraction) by puncturing tubes on top and bottom with a 21-gauge needle. Fractions were collected from each tube and 2.5 μl of each fraction were analyzed by a 10% SDS-polyacrylamide gel and Western blotting using an anti-HPV16 L1 antibody. [0050] Virus-like particles and capsomeres were separated from the fractions identified above by sedimentation on 10 to 50% sucrose gradients. Peak fractions from CsCl gradients were pooled and dialyzed for 2 hours against 5 mM HEPES (pH 7.5). Half of the dialysate was used to produce capsomeres by disassembly of intact VLPs overnight by adding EDTA (final concentration 50 mM), EGTA (50 mM), DOT (30 mM). NaCl (100 mM), and Tris/HCl, pH 8.0, (10 mM). As control, NaCl and Tris/HCl only were added to the other half. [0051] For analysis of capsomeres produced from disassembled VLPs, EDTA, EGTA, and DTT (final concentration 5 mM each) were added to the sucrose cushions which were centrifuged at 250,000×g for 2 to 4 hours at 4° C. Fractions were collected by puncturing tubes from the bottom. A 1:10 dilution of each fraction was then analyzed by antigen capture ELISA. EXAMPLE 4 Immunization Protocol for Production of Polyclonal Antisera and Monoclonal Antibodies [0052] Balb/c mice are immunized subcutaneously three times, every four weeks with approximately 60 μg of HPV chimeric capsomeres mixed 1:1 with complete or incomplete Freunds Adjuvants in a total volume of 100 μl. Six weeks after the third immunization. mice are sacrificed and blood is collected by cardiac puncture. EXAMPLE 5 Peptide ELISA to Quantitate Capsomere Formation [0053] Microtiter plates (Dynatech) are coated overnight with 50 μl of peptide E701 [Muller et al., 1982] at a concentration of 10 μg/ml in PBS. Wells are blocked for 2 hour at 37° C. with 100 μl of buffer containing 5% BSA and 0.05% Tween 20 in PBS and washed three times with PBS containing 0.05% Tween 20. After the third wash. 50 μl of sera diluted 1:5000 in BSA/Tween 20/PBS is added to each well and incubation carried out for 1 hour. Plates are washed again as before and 50 μl of goat-anti-mouse peroxidase conjugate is added at a 1:5000 dilution. After 1 hour, plates are washed and stained using ABTS substrate (0.2 mg/ml. 2.2′-Azino-bis(3-ethylbenzhiazoline-β-sulfonic acid in 0.1 M Na-Acetate-Phosphate buffer (pH 4.2) with 4 μl 30% H 2 O 2 per 10 ml). Extinction is measured after 1 hour at 490 nm in a Dynatech automated plate reader. EXAMPLE 6 Antigen Capture ELISA to Quantitate Capsomere Formation [0054] To allow relative quantification of virus-like particles and capsomeres in fractions of CsCl gradients. an antigen capture ELISA was utilized. Microtiter plates were coated overnight with 50 μl/well of a 1:500 dilution (final concentration of 2 μg per ml, in PBS) with a protein A purified mouse monoclonal antibody immunospecific for HPV 16 L1 (antibodies 25/C, MM07 and Ritti 1 were obtained from mice immunized with HPV 16 VLPs). Plates were blocked with 5% milk/PBS for 1 hour and 50 μl of fractions of CsCl gradients were added for 1 hour at 37° C. using a 1:300 dilution (in 5% milk/PBS). After three washings with PBS/0.05% Tween 20, 50 μl of a polyclonal rabbit antiserum (1:3000 dilution in milk/PBS). raised against HPV 16 VLPs was added and plates were incubated at 37° for 1 hour. Plates were washed again and further incubated with 50 μl of a goat-anti-rabbit peroxidase conjugate (Sigma) diluted 1:5000 in PBS containing 5% milk for 1 hour. After final washing, plates were stained with ABTS substrate for 30 minutes and extinction measured at 490 nm in a Dynatech automated plate reader. As a negative control. the assay also included wells coated only with PBS. [0055] To test monoclonal antibodies for capsomere specificity, VLPs with EDTA/DTT to disassemble particles. Treated particle preparations were assayed in the antigen-capture ELISA and readings compared to untreated controls. For disassembly. 40 μl of VLPs was incubated overnight at 4° C. in 500 μl of disruption buffer containing 30 mM DTT. 50 mM EGTA, 60 mM EDTA, 100 mM NaCl, and 100 mM Tris/HCl. pH 8.0. Aliquots of treated and untreated particles were used in the above capture ELISA in a 1:20-1:40 dilution. EXAMPLE 7 Hemagglutinin Inhibition Assay [0056] In order to determine the extent to which chimeric capsomere vaccines evoke production of neutralizing antibodies, a hemagglutination inhibition assay is carried out as briefly described below. This assay is based on previous observations that virus-like particles are capable of hemagglutinizing red blood cells. [0057] Mice are immunized with any of a chimeric capsomere vaccine and sera is collected as described above in Example 4. As positive controls, HPV16 L1 virus like particles (VLPs) and bovine PV1 (BPV) L1 VLPs are assayed in b parallel with a chimeric capsomere preparation. To establish a positive baseline, the HPV 16 or BPV1 VLPs are first incubated with or without sera collected from immunized mice after which red blood cells are added. The extent to which preincubation with mouse cera inhibits red blood cell hemagglutinization is an indication of the neutralizing capacity of the mouse sera. The experiments are then repeated using chimeric capsomeres in order to determine the neutralizing effect of the mouse sera on the vaccine. A brief protocol for the hemagglutination inhibition assay is described below. [0058] One hundred microliters of heparin (1000 usp units/ml) are added to 1 ml fresh mouse blood. Red blood cells are washed three times with PBS followed by centrifugation and resuspension in a volume of 10 ml. Next, erythrocytes are resuspended in 0.5 ml PBS and stored at 4° C. for up to three days. For the hemagglutinin assay. 70 μl of the suspension is used per well on a 96-well plate. [0059] Chimeric capsomere aliquots from CsCl gradients are dialyzed for one hour against 10 mM Hepes (pH 7.5) and 100 μl of two-fold serial dilutions in PBS are added to mouse erythrocytes in round-bottom 96-well microtiter plates which are further incubated for 3-16 hours at 4° C. For hemagglutination inhibition, capsomeres are incubated with dilutions of antibodies in PBS for 60 minutes at room temperature and then added to the erythrocytes. The level of erythrocyte hemagglutination, and therefore the presence of neutralizing antibodies, is determined by standard methods. [0060] In preliminary results, mouse sera generated against chimeric capsomeres comprising HPV16L1ΔC protein in association with E7 amino acid residues 1-98 was observed to inhibit hemagglutination by HPV16 VLPs, but not by BPV VLPs. The mouse sera was therefore positive for neutralizing antibodies against the human VLPs and this differential neutralization was most likely the result of antibody specificity for epitopes against which the antibodies were raised. [0061] Numerous modifications and variations in the invention as set forth in the above illustrative examples are expected to occur to those skilled in the art. Consequently only such limitations as appear in the appended claims should be placed on the invention. 1 28 1518 base pairs nucleic acid single linear DNA (genomic) CDS 1..1515 1 ATG TCT CTT TGG CTG CCT AGT GAG GCC ACT GTC TAC TTG CCT CCT GTC 48 Met Ser Leu Trp Leu Pro Ser Glu Ala Thr Val Tyr Leu Pro Pro Val 1 5 10 15 CCA GTA TCT AAG GTT GTA AGC ACG GAT GAA TAT GTT GCA CGC ACA AAC 96 Pro Val Ser Lys Val Val Ser Thr Asp Glu Tyr Val Ala Arg Thr Asn 20 25 30 ATA TAT TAT CAT GCA GGA ACA TCC AGA CTA CTT GCA GTT GGA CAT CCC 144 Ile Tyr Tyr His Ala Gly Thr Ser Arg Leu Leu Ala Val Gly His Pro 35 40 45 TAT TTT CCT ATT AAA AAA CCT AAC AAT AAC AAA ATA TTA GTT CCT AAA 192 Tyr Phe Pro Ile Lys Lys Pro Asn Asn Asn Lys Ile Leu Val Pro Lys 50 55 60 GTA TCA GGA TTA CAA TAC AGG GTA TTT AGA ATA CAT TTA CCT GAC CCC 240 Val Ser Gly Leu Gln Tyr Arg Val Phe Arg Ile His Leu Pro Asp Pro 65 70 75 80 AAT AAG TTT GGT TTT CCT GAC ACC TCA TTT TAT AAT CCA GAT ACA CAG 288 Asn Lys Phe Gly Phe Pro Asp Thr Ser Phe Tyr Asn Pro Asp Thr Gln 85 90 95 CGG CTG GTT TGG GCC TGT GTA GGT GTT GAG GTA GGT CGT GGT CAG CCA 336 Arg Leu Val Trp Ala Cys Val Gly Val Glu Val Gly Arg Gly Gln Pro 100 105 110 TTA GGT GTG GGC ATT AGT GGC CAT CCT TTA TTA AAT AAA TTG GAT GAC 384 Leu Gly Val Gly Ile Ser Gly His Pro Leu Leu Asn Lys Leu Asp Asp 115 120 125 ACA GAA AAT GCT AGT GCT TAT GCA GCA AAT GCA GGT GTG GAT AAT AGA 432 Thr Glu Asn Ala Ser Ala Tyr Ala Ala Asn Ala Gly Val Asp Asn Arg 130 135 140 GAA TGT ATA TCT ATG GAT TAC AAA CAA ACA CAA TTG TGT TTA ATT GGT 480 Glu Cys Ile Ser Met Asp Tyr Lys Gln Thr Gln Leu Cys Leu Ile Gly 145 150 155 160 TGC AAA CCA CCT ATA GGG GAA CAC TGG GGC AAA GGA TCC CCA TGT ACC 528 Cys Lys Pro Pro Ile Gly Glu His Trp Gly Lys Gly Ser Pro Cys Thr 165 170 175 AAT GTT GCA GTA AAT CCA GGT GAT TGT CCA CCA TTA GAG TTA ATA AAC 576 Asn Val Ala Val Asn Pro Gly Asp Cys Pro Pro Leu Glu Leu Ile Asn 180 185 190 ACA GTT ATT CAG GAT GGT GAT ATG GTT GAT ACT GGC TTT GGT GCT ATG 624 Thr Val Ile Gln Asp Gly Asp Met Val Asp Thr Gly Phe Gly Ala Met 195 200 205 GAC TTT ACT ACA TTA CAG GCT AAC AAA AGT GAA GTT CCA CTG GAT ATT 672 Asp Phe Thr Thr Leu Gln Ala Asn Lys Ser Glu Val Pro Leu Asp Ile 210 215 220 TGT ACA TCT ATT TGC AAA TAT CCA GAT TAT ATT AAA ATG GTG TCA GAA 720 Cys Thr Ser Ile Cys Lys Tyr Pro Asp Tyr Ile Lys Met Val Ser Glu 225 230 235 240 CCA TAT GGC GAC AGC TTA TTT TTT TAT TTA CGA AGG GAA CAA ATG TTT 768 Pro Tyr Gly Asp Ser Leu Phe Phe Tyr Leu Arg Arg Glu Gln Met Phe 245 250 255 GTT AGA CAT TTA TTT AAT AGG GCT GGT GCT GTT GGT GAA AAT GTA CCA 816 Val Arg His Leu Phe Asn Arg Ala Gly Ala Val Gly Glu Asn Val Pro 260 265 270 GAC GAT TTA TAC ATT AAA GGC TCT GGG TCT ACT GCA AAT TTA GCC AGT 864 Asp Asp Leu Tyr Ile Lys Gly Ser Gly Ser Thr Ala Asn Leu Ala Ser 275 280 285 TCA AAT TAT TTT CCT ACA CCT AGT GGT TCT ATG GTT ACC TCT GAT GCC 912 Ser Asn Tyr Phe Pro Thr Pro Ser Gly Ser Met Val Thr Ser Asp Ala 290 295 300 CAA ATA TTC AAT AAA CCT TAT TGG TTA CAA CGA GCA CAG GGC CAC AAT 960 Gln Ile Phe Asn Lys Pro Tyr Trp Leu Gln Arg Ala Gln Gly His Asn 305 310 315 320 AAT GGC ATT TGT TGG GGT AAC CAA CTA TTT GTT ACT GTT GTT GAT ACT 1008 Asn Gly Ile Cys Trp Gly Asn Gln Leu Phe Val Thr Val Val Asp Thr 325 330 335 ACA CGC AGT ACA AAT ATG TCA TTA TGT GCT GCC ATA TCT ACT TCA GAA 1056 Thr Arg Ser Thr Asn Met Ser Leu Cys Ala Ala Ile Ser Thr Ser Glu 340 345 350 ACT ACA TAT AAA AAT ACT AAC TTT AAG GAG TAC CTA CGA CAT GGG GAG 1104 Thr Thr Tyr Lys Asn Thr Asn Phe Lys Glu Tyr Leu Arg His Gly Glu 355 360 365 GAA TAT GAT TTA CAG TTT ATT TTT CAA CTG TGC AAA ATA ACC TTA ACT 1152 Glu Tyr Asp Leu Gln Phe Ile Phe Gln Leu Cys Lys Ile Thr Leu Thr 370 375 380 GCA GAC GTT ATG ACA TAC ATA CAT TCT ATG AAT TCC ACT ATT TTG GAG 1200 Ala Asp Val Met Thr Tyr Ile His Ser Met Asn Ser Thr Ile Leu Glu 385 390 395 400 GAC TGG AAT TTT GGT CTA CAA CCT CCC CCA GGA GGC ACA CTA GAA GAT 1248 Asp Trp Asn Phe Gly Leu Gln Pro Pro Pro Gly Gly Thr Leu Glu Asp 405 410 415 ACT TAT AGG TTT GTA ACC TCC CAG GCA ATT GCT TGT CAA AAA CAT ACA 1296 Thr Tyr Arg Phe Val Thr Ser Gln Ala Ile Ala Cys Gln Lys His Thr 420 425 430 CCT CCA GCA CCT AAA GAA GAT CCC CTT AAA AAA TAC ACT TTT TGG GAA 1344 Pro Pro Ala Pro Lys Glu Asp Pro Leu Lys Lys Tyr Thr Phe Trp Glu 435 440 445 GTA AAT TTA AAG GAA AAG TTT TCT GCA GAC CTA GAT CAG TTT CCT TTA 1392 Val Asn Leu Lys Glu Lys Phe Ser Ala Asp Leu Asp Gln Phe Pro Leu 450 455 460 GGA CGC AAA TTT TTA CTA CAA GCA GGA TTG AAG GCC AAA CCA AAA TTT 1440 Gly Arg Lys Phe Leu Leu Gln Ala Gly Leu Lys Ala Lys Pro Lys Phe 465 470 475 480 ACA TTA GGA AAA CGA AAA GCT ACA CCC ACC ACC TCA TCT ACC TCT ACA 1488 Thr Leu Gly Lys Arg Lys Ala Thr Pro Thr Thr Ser Ser Thr Ser Thr 485 490 495 ACT GCT AAA CGC AAA AAA CGT AAG CTG TAA 1518 Thr Ala Lys Arg Lys Lys Arg Lys Leu 500 505 505 amino acids amino acid linear protein 2 Met Ser Leu Trp Leu Pro Ser Glu Ala Thr Val Tyr Leu Pro Pro Val 1 5 10 15 Pro Val Ser Lys Val Val Ser Thr Asp Glu Tyr Val Ala Arg Thr Asn 20 25 30 Ile Tyr Tyr His Ala Gly Thr Ser Arg Leu Leu Ala Val Gly His Pro 35 40 45 Tyr Phe Pro Ile Lys Lys Pro Asn Asn Asn Lys Ile Leu Val Pro Lys 50 55 60 Val Ser Gly Leu Gln Tyr Arg Val Phe Arg Ile His Leu Pro Asp Pro 65 70 75 80 Asn Lys Phe Gly Phe Pro Asp Thr Ser Phe Tyr Asn Pro Asp Thr Gln 85 90 95 Arg Leu Val Trp Ala Cys Val Gly Val Glu Val Gly Arg Gly Gln Pro 100 105 110 Leu Gly Val Gly Ile Ser Gly His Pro Leu Leu Asn Lys Leu Asp Asp 115 120 125 Thr Glu Asn Ala Ser Ala Tyr Ala Ala Asn Ala Gly Val Asp Asn Arg 130 135 140 Glu Cys Ile Ser Met Asp Tyr Lys Gln Thr Gln Leu Cys Leu Ile Gly 145 150 155 160 Cys Lys Pro Pro Ile Gly Glu His Trp Gly Lys Gly Ser Pro Cys Thr 165 170 175 Asn Val Ala Val Asn Pro Gly Asp Cys Pro Pro Leu Glu Leu Ile Asn 180 185 190 Thr Val Ile Gln Asp Gly Asp Met Val Asp Thr Gly Phe Gly Ala Met 195 200 205 Asp Phe Thr Thr Leu Gln Ala Asn Lys Ser Glu Val Pro Leu Asp Ile 210 215 220 Cys Thr Ser Ile Cys Lys Tyr Pro Asp Tyr Ile Lys Met Val Ser Glu 225 230 235 240 Pro Tyr Gly Asp Ser Leu Phe Phe Tyr Leu Arg Arg Glu Gln Met Phe 245 250 255 Val Arg His Leu Phe Asn Arg Ala Gly Ala Val Gly Glu Asn Val Pro 260 265 270 Asp Asp Leu Tyr Ile Lys Gly Ser Gly Ser Thr Ala Asn Leu Ala Ser 275 280 285 Ser Asn Tyr Phe Pro Thr Pro Ser Gly Ser Met Val Thr Ser Asp Ala 290 295 300 Gln Ile Phe Asn Lys Pro Tyr Trp Leu Gln Arg Ala Gln Gly His Asn 305 310 315 320 Asn Gly Ile Cys Trp Gly Asn Gln Leu Phe Val Thr Val Val Asp Thr 325 330 335 Thr Arg Ser Thr Asn Met Ser Leu Cys Ala Ala Ile Ser Thr Ser Glu 340 345 350 Thr Thr Tyr Lys Asn Thr Asn Phe Lys Glu Tyr Leu Arg His Gly Glu 355 360 365 Glu Tyr Asp Leu Gln Phe Ile Phe Gln Leu Cys Lys Ile Thr Leu Thr 370 375 380 Ala Asp Val Met Thr Tyr Ile His Ser Met Asn Ser Thr Ile Leu Glu 385 390 395 400 Asp Trp Asn Phe Gly Leu Gln Pro Pro Pro Gly Gly Thr Leu Glu Asp 405 410 415 Thr Tyr Arg Phe Val Thr Ser Gln Ala Ile Ala Cys Gln Lys His Thr 420 425 430 Pro Pro Ala Pro Lys Glu Asp Pro Leu Lys Lys Tyr Thr Phe Trp Glu 435 440 445 Val Asn Leu Lys Glu Lys Phe Ser Ala Asp Leu Asp Gln Phe Pro Leu 450 455 460 Gly Arg Lys Phe Leu Leu Gln Ala Gly Leu Lys Ala Lys Pro Lys Phe 465 470 475 480 Thr Leu Gly Lys Arg Lys Ala Thr Pro Thr Thr Ser Ser Thr Ser Thr 485 490 495 Thr Ala Lys Arg Lys Lys Arg Lys Leu 500 505 297 base pairs nucleic acid single linear DNA (genomic) CDS 1..294 3 ATG CAT GGA GAT ACA CCT ACA TTG CAT GAA TAT ATG TTA GAT TTG CAA 48 Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp Leu Gln 1 5 10 15 CCA GAG ACA ACT GAT CTC TAC TGT TAT GAG CAA TTA AAT GAC AGC TCA 96 Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp Ser Ser 20 25 30 GAG GAG GAG GAT GAA ATA GAT GGT CCA GCT GGA CAA GCA GAA CCG GAC 144 Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 35 40 45 AGA GCC CAT TAC AAT ATT GTA ACC TTT TGT TGC AAG TGT GAC TCT ACG 192 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 50 55 60 CTT CGG TTG TGC GTA CAA AGC ACA CAC GTA GAC ATT CGT ACT TTG GAA 240 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 65 70 75 80 GAC CTG TTA ATG GGC ACA CTA GGA ATT GTG TGC CCC ATC TGT TCT CAG 288 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 85 90 95 AAA CCA TAA 297 Lys Pro 98 amino acids amino acid linear protein 4 Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp Leu Gln 1 5 10 15 Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp Ser Ser 20 25 30 Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 35 40 45 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 50 55 60 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 65 70 75 80 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 85 90 95 Lys Pro 34 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 5 CCCCGATATC GCCTTTAATG TATAAATCGT CTGG 34 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 6 CCCCGATATC TCAAATTATT TTCCTACACC TAGTG 35 40 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 7 AAAGATATCT TGTAGTAAAA ATTTGCGTCC TAAAGGAAAC 40 44 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 8 AAAGATATCT AATCTACCTC TACAACTGCT AAACGCAAAA AACG 44 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 9 AAAAGATATC ATGCATGGAG ATACACCTAC ATTGC 35 34 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 10 TTTTGATATC GGCTCTGTCC GGTTCTGCTT GTCC 34 44 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 11 TTTTGATATC CTTGCAACAA AAGGTTACAA TATTGTAATG GGCC 44 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 12 AAAAGATATC TGGTTTCTGA GAACAGATGG GGCAC 35 38 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 13 TTTTGATATC GATTATGAGC AATTAAATGA CAGCTCAG 38 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 14 TTTTGATATC GTCTACGTGT GTGCTTTGTA CGCAC 35 39 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 15 TTTATCGATA TCGGTCCAGC TGGACAAGCA GAACCGGAC 39 39 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 16 TTTTGATATC GATGCCCATT ACAATATTGT AACCTTTTG 39 294 base pairs nucleic acid single linear DNA (genomic) CDS 1..291 17 ATG AGT CTT CTA ACC GAG GTC GAA ACG CTT ACC AGA AAC GGA TGG GAG 48 Met Ser Leu Leu Thr Glu Val Glu Thr Leu Thr Arg Asn Gly Trp Glu 1 5 10 15 TGC AAA TGC AGC GAT TCA AGT GAT CCT CTC ATT ATC GCA GCG AGT ATC 96 Cys Lys Cys Ser Asp Ser Ser Asp Pro Leu Ile Ile Ala Ala Ser Ile 20 25 30 ATT GGG ATC TTG CAC TTG ATA TTG TGG ATT TTT TAT CGT CTT TTC TTC 144 Ile Gly Ile Leu His Leu Ile Leu Trp Ile Phe Tyr Arg Leu Phe Phe 35 40 45 AAA TGC ATT TAT CGT CGC CTT AAA TAC GGT TTG AAA AGA GGG CCT TCT 192 Lys Cys Ile Tyr Arg Arg Leu Lys Tyr Gly Leu Lys Arg Gly Pro Ser 50 55 60 ACG GAA GGA GCG CCT GAG TCT ATG AGG GAA GAA TAT CGG CAG GAA CAG 240 Thr Glu Gly Ala Pro Glu Ser Met Arg Glu Glu Tyr Arg Gln Glu Gln 65 70 75 80 CAG AGT GCT GTG GAT GTT GAC GAT GTT CAT TTT GTC AAC ATA GAG CTG 288 Gln Ser Ala Val Asp Val Asp Asp Val His Phe Val Asn Ile Glu Leu 85 90 95 GAG TAA 294 Glu 97 amino acids amino acid linear protein 18 Met Ser Leu Leu Thr Glu Val Glu Thr Leu Thr Arg Asn Gly Trp Glu 1 5 10 15 Cys Lys Cys Ser Asp Ser Ser Asp Pro Leu Ile Ile Ala Ala Ser Ile 20 25 30 Ile Gly Ile Leu His Leu Ile Leu Trp Ile Phe Tyr Arg Leu Phe Phe 35 40 45 Lys Cys Ile Tyr Arg Arg Leu Lys Tyr Gly Leu Lys Arg Gly Pro Ser 50 55 60 Thr Glu Gly Ala Pro Glu Ser Met Arg Glu Glu Tyr Arg Gln Glu Gln 65 70 75 80 Gln Ser Ala Val Asp Val Asp Asp Val His Phe Val Asn Ile Glu Leu 85 90 95 Glu 40 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 19 TTTTGATATC GATATGGAAT GGCTAAAGAC AAGACCAATC 40 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 20 TTTTGATATC GTTGTTTGGA TCCCCATTCC CATTG 35 24 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 21 GTTATGACAT ACATACATTC TATG 24 35 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 22 CCATGCATTC CTGCTTGTAG TAAAAATTTG CGTCC 35 29 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 23 CTACAAGCAG GAATGCATGG AGATACACC 29 36 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 24 CATCTGAAGC TTAGTAATGG GCTCTGTCCG GTTCTG 36 38 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 25 CATCTGAAGC TTATCAATAT TGTAATGGGC TCTGTCCG 38 54 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 26 CATCTGAAGC TTACTTGCAA CAAAAGGTTA CAATATTGTA ATGGGCTCTG TCCG 54 69 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 27 CATCTGAAGC TTAAAGCGTA GAGTCACACT TGCAACAAAA GGTTACAATA TTGTAATGGG 60 CTCTGTCCG 69 47 base pairs nucleic acid single linear other nucleic acid /desc = “Primer” 28 CATCTGAAGC TTATTGTACG CACAACCGAA GCGTAGAGTC ACACTTG 47

Vaccine formulations comprising viral capsomeres are disclosed along with methods for their production. Therapeutic and prophylactic methods of use for the vaccine formulations are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application relates to and claims priority to German Patent Application 102015220178.3, filed Oct. 16, 2015, the entirety of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION Field of the Invention [0002] The invention relates to a capacitive pressure measuring cell for detecting the pressure of a medium adjacent to the pressure measuring cell according to the preamble of claim 1 and a pressure measuring device including such a pressure measuring cell. [0003] Capacitive pressure measuring devices or pressure sensors are used in many industrial fields for pressure measurements. They often comprise a ceramic pressure measuring cell as a transducer for the process pressure and an evaluation unit for signal processing. [0004] Typical measuring cells consist of a compact unit comprising a ceramic base body and a membrane, wherein a glass solder ring is disposed between the base body and the membrane. The cavity thus obtained between the base body and the membrane allows the longitudinal movement of the membrane due to a pressure impact. At the bottom side of the membrane and at the opposite upper side of the base body respective electrodes are provided which together form a measuring capacitor. By the action of pressure a deformation of the membrane is caused resulting in a change in capacitance of the measuring capacitor. [0005] For contacting the electrodes through holes are provided in the base body of the pressure measuring cell on the opposite side of the membrane in a number corresponding to the number of the electrodes. These through holes lead up to the electrodes and comprise an electrically conductive coating at their inner wall over their entire length. A contact pin is inserted into the exit opening of each through hole on the upper side of the base body and an electrical contact with the coating is made using a solder joint such that the electrode can be electrically contacted via the pin. [0006] Such a pressure measurement cell is inter alia known from the documents DE 102012213572 A1, DE 102012208757 A1 and DE 102013213857 A1 of the present applicant, wherein in the former in order to make an electrical contact the printed circuit board rests directly on the coating and thus no pin is required. The production of vias in a substrate is known, for example, from DE 10243961 A1. [0007] A key consideration in such pressure measuring cells is inter alia the mechanical pressure limit, that is how long the measuring cell can withstand a predetermined excess pressure before it is damaged and thus the risk arises that the pressurized medium passes into the interior of the measuring device. Although the strength can be increased when a thicker base body is provided, this measure, however, results in manufacturing problems. For example, with increasing thickness of the base body the formation of the through hole and the conductive inner coating within the through-hole becomes more difficult. Moreover, thereby also the overall construction of the measuring device is extended, which is contrary in particular to the requirements of a configuration as compact as possible. [0008] It is an object of the invention to improve the mechanical pressure limit of the pressure measuring cell without changing the fundamental configuration of known pressure measuring cells of the type in question, in particular as regards the material thickness. SUMMARY OF THE INVENTION [0009] This object is achieved by a pressure measuring cell comprising the features of claim 1 and by an electronic pressure measuring device according to claim 7 . Advantageous embodiments of the invention are specified in the subclaims. [0010] According to the invention the end portions of the through holes at the upper side of the base body each have a funnel shaped extension, wherein the exit edge of each funnel-shaped extension is formed in the shape of an ellipse such that the notch effect is smaller than in a circular form. Herein, the funnel shaped extension is configured such that each exit opening of the through holes at the upper side of the base body at least partially forms a bevel—also referred to as counterbore. By means of the elliptical profile of the exit edges the bevels extend with varying angles. Preferably, the major axes of the ellipses are aligned tangentially. It should be noted that the term “elliptical shape” also means any oval shapes. [0011] The thus achieved technical effect is the reduction of the mechanical stresses obtained by the pressure impact in the base body. This effect is achieved by increasing the radius at the exit opening of the through hole at the upper side of the base body of the pressure measuring cell, while the diameter of the through hole itself remains unchanged. In simple terms this can be expressed so that the radially extending stress flows at the surface of the base body are bypassed by the elliptical shape quasi “laminar” around the obstacle, that is the through hole. Specifically, this means that by means of the elliptical shape the respective occurring notch effect is smaller compared to a circular shape such that in particular occurring tensile stresses are reduced. As a result, by reducing mechanical stresses an increase in strength is achieved which ultimately leads to the fact that the pressure measuring cell can withstand predetermined excessive pressures for a longer time or even higher excessive pressures for the same configuration and unchanged dimensions. [0012] Preferably, the major axes of the ellipses are therefore oriented tangentially. The bevels advantageously have a uniform, i.e. stepless behaviour from the circumference of the through hole up to their exit edge. This inter alia brings about advantages in manufacturing. [0013] Although the invention relates to a capacitive pressure measuring cell it is likewise applicable to resistive measuring cells in which the pressure measurement takes place by means of strain gauges and which comprise a ceramic base body. [0014] The pressure measuring device according to the invention substantially consists of a process connection, a housing and a pressure measuring cell according to the invention. The process connection mostly includes the pressure measuring cell and provides the mechanical connection to a container which accommodates the medium to be measured. The housing is mounted onto the process connection. In the housing in particular the electronic unit necessary for processing and conditioning the measured values into a measurement signal is disposed. In addition, a connector for power and/or signal transmission as well as a display and control unit may be provided at the housing. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention will now be explained with reference to an exemplary embodiment shown in the drawings. In the drawings: [0016] FIG. 1 is a schematic cross-sectional view of a pressure measuring cell according to the invention; and [0017] FIG. 2 is a top view of a pressure measuring cell according to the invention. DETAILED DESCRIPTION [0018] In the following description of the preferred embodiments like reference numerals designate identical or comparable components. [0019] FIG. 1 shows a capacitive pressure measuring cell 1 comprising a ceramic base body 3 and a measuring membrane 2 likewise made of ceramic. The measuring membrane 2 and the base body 3 are held spaced apart from each other at the edge by means of a spacer 13 made e.g. of glass, glass solder or a glass alloy and are connected to each other, such that a measuring chamber 4 is formed between the membrane 2 and the base body 4 . [0020] The measuring membrane 2 contacts at its outer side a medium the pressure of which is to be measured by means of the measuring cell 1 . The measuring chamber 4 between the base body 3 and the membrane 2 enables the longitudinal movement of the membrane 2 due to a pressure impact. At the inner sides of the membrane 2 and the opposite base body 3 respective electrodes 10 , 11 , 12 are provided, which together form at least one measuring capacitor. The pressure impact causes a deformation of the membrane 2 resulting in a change in capacitance of the measuring capacitor. [0021] For contacting the electrodes 10 , 11 , 12 a respective through hole 20 is provided in the base body 3 . The through holes 20 are provided with a conductive coating. On the upper side 3 a of the body 3 a respective contact pin 23 is inserted into the exit openings 21 of the through holes 20 which is preferably connected electrically conductive to the coating by means of a solder. For connecting the electrode 10 disposed on the membrane 2 in addition an electrical connection over or through the spacer 13 is required. In this way the electrodes 10 , 11 , 12 can be electrically contacted from the upper side 3 a of the body 3 , i.e. the change in capacitance occurring between the electrodes due to a pressure impact can be tapped. [0022] The through hole 20 in the center is shown in phantom because actually it is not visible in a section through the center of the pressure measuring cell. Here it is again stressed that the view shown in FIG. 1 is a schematic diagram or principle sketch in which the focus is directed at the illustration of the invention. In particular, the contacting of the electrode 12 by means of the inclined extending through hole 20 can be realized differently. In approximate agreement with FIG. 2 this representation has been selected here. [0023] In FIG. 1 the end portions 21 a of the through holes 20 with the funnel-shaped extensions can be seen. According to the invention the exit edges of the funnel-shaped extensions are not configured circular, but elliptical, as is obvious in FIG. 2 . [0024] FIG. 2 shows a top view of a pressure measuring cell according to the invention. The exit openings 21 of the through holes 20 at the upper side 3 a of the base body 3 are arranged along an imaginary circular line K. The circular line K has only been shown here in dashed lines in order to illustrate the aspect of the arrangement. Also indicated is a respective contact pin 23 which is disposed at the center in the through holes 20 . [0025] During a pressure impact onto the measuring cell 1 the membrane 2 and the base body 3 respectively experience a compression on the side facing the medium and an elongation on the opposite side. In this case the elongation side and in particular the upper side 3 a of the base body is critical to the mechanical pressure limit of the measuring cell 1 , because with a cracked membrane 2 in fact no measurements are possible, but the medium yet cannot penetrate into the interior of the pressure measuring device. In order to improve the mechanical pressure limit of the measuring cell 1 the tensile stresses caused by the elongation must be reduced. [0026] This is achieved by an enlargement of the end portions 21 of the through holes 20 disposed at the upper side 3 a of the base body. However, the size of the through hole 20 itself should be made as small as possible in order to simplify the contacting of the pins 23 with the electrically conductive inner coating of the through hole 20 . The solution thus provides a bevel 22 as flat as possible which does not change the diameter of the through hole 20 itself, but increases or extends its exit opening 21 on the upper side 3 a in such a manner that thereby a significant reduction in the tensile stresses is achieved which ultimately leads to an improvement of the mechanical pressure limit of the entire measuring cell 1 . [0027] However, the spatial extent of this enlargement of the exit opening 21 is limited. On the one hand measuring cells of the type in question typically have a diameter of about 2 cm and on the other hand the through holes 20 must be located in the edge region of the measuring cell 1 in order not to affect the pressure-induced movement of the measuring cell 1 in the interior area. Consequently, it is useful to configure the exit openings 21 of the through holes 20 or their exit edges in an elliptical shape in order to achieve an enlargement by an extension in the tangential direction, while in the radial direction the enlargement can be made minimal. Here, the enlargement in the radial direction indeed may be dispensed with such that the smallest radius of the ellipse corresponds to the radius of the through hole 20 or the extension of the minor axis corresponds to the diameter of the through hole 20 . Studies on this have shown that with a ratio between the largest diameter and the smallest diameter or between the extension of the main axis and the extension of the minor axis of the ellipse of 2:1 an optimum between the spatial extension and a reduction of the tensile stresses is achieved. [0028] The elliptical shape of the exit edges in this case represents a preferred embodiment of the invention, however, in principle any oval shapes are conceivable. It is essential that by means of an enlargement of the through holes 20 their radius or circumference is increased. [0029] Although the exemplary embodiment shows a capacitive pressure measuring cell the invention can likewise be applied in resistive measuring cells with strain gauges when the base body is made of ceramic. The base body is often made of steel, but in some cases there are also applications where it is preferred to implement the base of ceramic. In this case there may be a need to implement the connections to the strain gauges through the ceramic body by means of through holes. Since here, too, the ceramic body experiences a pressure-induced longitudinal movement, the thereby occurring mechanical stresses can be minimized by providing the through holes respectively with a bevel and an oval or elliptical exit edge according to the invention, whereby as a result an improvement of the mechanical pressure limit is achieved.

The invention relates to a capacitive pressure measuring cell for detecting the pressure of a medium adjacent to the pressure measuring cell, comprising a ceramic elastic measuring membrane, the first side of which at least partially contacts the medium and the second side of which facing away from the medium comprises a measuring electrode, and a ceramic cylindrical basic body disposed opposite to the second side of the measuring membrane and comprising at least one counter electrode which forms a measuring capacitance with the measuring electrode.

The present application claims the filing benefit of co-pending U.S. Provisional Patent Application No. 60/862,914, filed Oct. 25, 2006, which is incorporated by reference herein in its entirety. TECHNICAL FIELD The present invention relates generally to machinery and mechanisms that operate in a cyclical manner, and more particularly to devices that facilitate cyclically operating such machinery and mechanisms. BACKGROUND Many machines and mechanisms operate in a cyclical manner. For example, rotating machinery such as turbines rotors, and reciprocating mechanisms such as paint shakers, exhibit cyclical motion. In use, these machines and mechanisms may be exposed to varying load conditions. However, many cyclically-operated machines and mechanisms are not able to accommodate varying loads while maintaining desired performance without substantial increases in power consumed. A need therefore exists for a simple, efficient system for driving cyclical machines and mechanisms, and for accommodating varying load conditions. SUMMARY A magnetic drive in accordance with the one aspect of the present disclosure overcomes the foregoing and other shortcomings of the prior systems for driving cyclical machines and mechanisms. In one embodiment, the magnetic drive includes an electrically conductive coil defining a bore and having first and second oppositely disposed ends. A magnetic member is movable from a first position outside the bore and adjacent the first end of the coil, through the bore to a second position outside the bore and adjacent the second end of the coil. The magnetic drive further includes a control that provides current to the coil to generate a magnetic field that interacts with the magnetic member. The control is able to reverse the direction of current through the coil and thereby act on the magnetic member as desired. In another aspect of the present disclosure, a counterbalance mechanism is provided for offsetting a load applied to a supporting structure. In one embodiment, the counterbalance includes a biasing member that is adapted to be coupled to a load support for reacting against a load applied to the load support. The counterbalance further includes a lever arm coupled to the biasing member. The lever arm is selectively positionable relative to the biasing member to vary a preload of the biasing member. The counterbalance may further include a pivot that cooperates with the lever arm and which is selectively positionable relative to the lever arm to vary the preload of the biasing member. In yet another aspect of the present disclosure, an apparatus for reciprocating a person includes a frame and a support platform that is constrained to move in a substantially vertical direction relative to the frame. The apparatus includes a counterbalance, as described above, with a biasing member coupled to the support platform and a lever arm coupled to the biasing member and the frame. The lever arm is selectively adjustable to vary a preload applied by the biasing member on the support platform. While various embodiments are discussed in detail herein, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention in sufficient detail to enable one of ordinary skill in the art to which the invention pertains to make and use the invention. FIG. 1 is a perspective view depicting an exemplary apparatus for reciprocating an infant support, with a cover of the housing shown in phantom. FIG. 2 is perspective view of the interior components of the apparatus of FIG. 1 . FIG. 3A is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a raised position. FIG. 3B is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a vertically centered position. FIG. 3C is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a lowered position. FIGS. 4A-4F are cross-sectional elevation views of a magnetic drive used with the apparatus of FIG. 1 , depicting various positions of a magnetic member. FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 2 . DETAILED DESCRIPTION FIG. 1 depicts an exemplary cyclically operated apparatus 10 including an exemplary magnetic drive 12 and a load off-setting, or counterbalancing, device 14 in accordance with the principles of the present disclosure. In this embodiment, the apparatus 10 is configured for reciprocating an infant so as to soothe the infant in a manner similar to that described in U.S. Pat. No. 6,966,082, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. It will be understood, however, that the drive and load off-setting devices 12 , 14 described herein may alternatively be used in various other mechanisms, or may be used independently of one another. Referring to FIGS. 1 , 2 , and 5 , the apparatus 10 includes a frame 16 having first and second spaced frame members 18 , 20 interconnected by transverse beam members 22 , 24 . In the embodiment shown, the frame members 18 , 20 comprise substantially parallel, vertically-extending sidewalls 26 , 28 . The frame 16 may include adjustable feet or casters 30 to support the frame 16 above a floor surface, and the frame 16 , as well as other components of the apparatus 10 may be enclosed in a housing 32 . As shown in FIGS. 3A , 3 B, and 3 C, housing 32 may comprise a removable upper cover 32 a and a lower base portion 32 b. The apparatus 10 further includes a pair of spaced, parallel upper control arms 34 , 36 and a pair of spaced, parallel lower control arms 38 , 40 (see FIGS. 3C and 5 ) disposed between the vertically extending sidewalls 26 , 28 of the frame 16 . Respective first ends 34 a , 36 a of the upper control arms 34 , 36 and first ends 38 a , 40 a of the lower control arms 38 , 40 are pivotally coupled to the frame 16 by pinned connections 42 , 44 . The respective second ends 34 b , 36 b of the upper control arms 34 , 36 (see FIGS. 3A and 5 ) and first ends 38 b , 40 b of the lower control arms 38 , 40 are pivotally coupled to a support platform 46 by pinned connections 48 , 50 , whereby the upper control arms 34 , 36 and lower control arms 38 , 40 are movable with the support platform 46 to constrain movement of the support platform 46 in a substantially vertical direction. A seat mount 52 may be secured to the support platform 46 to facilitate coupling an infant support 54 to the support platform 46 , whereby the infant support 54 will be constrained for movement with the support platform 46 in a substantially vertical direction. Travel limiting stops, such as a lower limit bumper 56 ( FIG. 5 ) extending downwardly from support platform 46 , and an upper limit bumper (not shown) disposed between the lower control arms 38 , 40 and frame members 18 , 20 , may be provided to control the limits of travel of the support platform 46 . While the travel stops are shown and described herein as bumpers, it will be recognized that various other devices and methods may be used to limit the travel of platform 46 . While this embodiment is described as being configured to accommodate an infant support 54 , it will be recognized that the apparatus may alternatively be used to reciprocate a support for a range of persons, from youths to adults, in a manner similar to that described in co-pending U.S. application Ser. No. 11/257,877, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. In the embodiment shown, the frame members 18 , 20 , the upper control arms 34 , 36 , lower control arms 38 , 40 , and support platform 46 are formed from sheet metal that has been stamped or otherwise worked or machined to form the respective components of the apparatus. It will be recognized, however, that various other methods for forming the frame members 18 , 20 , upper control arms 34 , 36 , lower control arms 38 , 40 and support platform 46 may alternatively be used. For example, and not as limitation, the frame members 18 , 20 , upper control arms 34 , 36 , lower control arms 38 , 40 and support platform 46 may be formed by molding, casting, machining, or various other methods suitable for fabricating the respective components. With continued reference to FIGS. 1 and 2 , and referring further to FIG. 5 , the apparatus 10 may further include a tunable load-offsetting, or counterbalance, mechanism 14 for accommodating varying loads that may be applied to the support platform 46 . In the embodiment shown, the counterbalance mechanism 14 comprises a biasing member 60 disposed between the support platform 46 and the frame 16 . In this embodiment, the biasing member 60 is a spiral torsion spring having a first end 62 operatively coupled to the support platform 46 , and a second end 64 coupled to a spring lever 66 for selectively adjusting the preload, or initial deflection, of the spiral torsion spring 60 to correspond to a given load applied to the support platform 46 . The spring lever 66 comprises an elongate member having a first end 68 pivotally coupled to the support platform 46 , and a second end 70 cantilevered outwardly from the support platform 46 in a direction between the upper control arms 34 , 36 , the lower control arms 38 , 40 , and the vertically extending sidewalls 26 , 28 of the frame 16 . The second end 70 of the spring lever 66 is biased in a direction toward the lower control arms 38 , 40 by the spiral torsion spring 60 . The spiral torsion spring 60 is coupled to the support platform 46 by a pair of semi-circular disks 72 that are pivotally coupled to the support platform 46 by an arbor 74 around which the spiral torsion spring 60 is wound. With the first end 62 of the spiral torsion spring 60 connected to the disks 72 , an initial, constant preload of the spiral torsion spring 60 may be selectively adjusted by rotating the disks 72 relative to the support platform 46 and then securing the disks 72 at a desired angular position relative to the support platform 46 . In the embodiment shown, a plurality of apertures 74 spaced radially from the arbor are provided around the periphery of the disks 72 and the disks are secured to the support platform 46 by inserting a pin (not shown) through at least one of the apertures 74 and through a corresponding aperture 76 formed in the support platform 46 . The counterbalance mechanism 14 further includes an adjustable pivot, or fulcrum 80 , that is selectively positionable along the length of the spring lever 66 to thereby vary a preload of the platform without changing the initial deflection of the spiral torsion spring 60 . With the platform deflection substantially constant for all preloads, the system resonant frequency will also remain constant. In the embodiment shown, the fulcrum 80 comprises a roller supported on a shaft 82 extending between the vertical walls 26 , 28 of the first and second frame members 18 , 20 . The shaft 82 is received in corresponding slots 84 , 86 formed in the vertical walls 26 , 28 of the frame members 18 , 20 whereby the roller 80 may be maneuvered to various positions along the spring lever 66 by moving the shaft 82 along the slots 84 , 86 . To facilitate positioning the shaft 82 and roller 80 at a desired location along the slots 84 , 86 , pinion gears 88 are provided on the shaft 82 and are rotationally fixed to the shaft 82 at respective ends 90 of the shaft 82 that extend outwardly from the vertical walls 26 , 28 , as shown in FIG. 2 . The pinion gears 88 intermesh with corresponding rack gears 92 provided on the vertical walls 26 , 28 of the frame members 18 , 20 , whereby the position of the shaft 82 and roller 80 may be selected by turning the shaft 82 to cause the pinion gears 88 to move along the rack gears 92 to a desired location. Knobs 94 may be provided on the respective ends 90 of the shaft 82 to facilitate turning the shaft 82 and pinion gears 88 . With the spiral torsion spring 60 connected between the support platform 46 and the spring lever 66 , and with the spring lever 66 being pivoted about the arbor 74 of the spiral torsion spring 60 , a load applied to the support platform 46 is supported as a sprung mass by the spiral torsion spring 60 . Moreover, the static vertical position of the platform 46 and supported load relative to the frame 16 may be selectively adjusted by manipulating the shaft 82 to cause the roller 80 to move along the spring lever 66 , as described above. The support platform 46 and load, together with the spiral torsion spring 60 , therefore comprise a spring-mass system that exhibits a particular natural frequency. The support platform 46 and supported load may thus be moved upwardly and downwardly, supported on the spiral torsion spring 60 , while the upper control arms 34 , 36 and lower control arms 38 , 40 constrain the upward and downward movement in a substantially vertical direction. The natural frequency of the spring-mass system is related to the static deflection of the supported load upon the spiral torsion spring 60 . Accordingly, by adjusting the static vertical height of the support platform 46 relative to the frame 16 , using the roller 80 and spring lever 66 , the apparatus 10 may be adjusted or tuned to accommodate a range of loads supported on the support platform 46 while maintaining the natural frequency of the spring-mass system. Alternatively, the apparatus 10 may be adjusted with a given load to tune the spring-mass system to a desired natural frequency. Referring to FIGS. 2 , 5 , and 4 A- 4 F, in another aspect, the apparatus 10 may include a magnetic drive 12 mounted to the frame 16 and operatively coupled to the support platform 46 to move the support platform 46 upwardly and downwardly in a cyclical fashion. In the embodiment shown, the magnetic drive 12 includes an electric coil 100 comprising conductive wire wound to define a cylindrical barrel 102 having a central bore 104 with oppositely disposed first and second ends 106 , 108 . A magnetic member 110 is sized to be received within the bore 104 of the electric coil 100 whereby the magnetic member 110 may be moved from a first position outside the bore 104 and spaced from the first end 106 of the bore 104 (see FIG. 4A ), through the bore 104 , to a second position outside the bore 104 and spaced from the second end 108 of the bore 104 (see FIG. 4E ). In the embodiment shown, the magnetic member 110 comprises a stack of individual magnets 112 , however, it will be recognized that magnetic member 110 may alternatively comprise a single, unitary magnet. In another embodiment, all components of the drive 12 , except the magnetic member 110 , comprise non-ferrous materials When electric current is passed through the coil 100 , a magnetic field is generated that interacts with the magnetic member 110 . Depending upon the direction of current through the coil 100 , the magnetic field generated by the coil 100 may attract the magnetic member 110 , thereby pulling the magnetic member 110 in a direction into the bore 104 , or the generated magnetic field may repel the magnetic member 110 , effectively pushing the magnetic member 110 out from the bore 104 . When the magnetic member 110 is coupled to a moveable portion of a machine or device, the electric coil 100 can be selectively operated to impart motion to the device. To this end, the drive 12 may include a control 114 (see FIG. 1 ) operable to selectively provide current to the coil 100 and to selectively change the direction of the current, as needed, to move the magnetic member 110 through the bore 104 and thereby impart corresponding motion to the device. The magnetic drive 12 is particularly useful when the motion of the device to be moved is cyclical, such as the cyclical reciprocation of the apparatus 10 shown and described herein. In the embodiment shown, the magnetic member 110 is supported on a rod 116 extending downwardly from the support platform 46 and is positioned to be received through the bore 104 of the electric coil 100 as the support platform 46 is reciprocated in a substantially vertical direction as discussed above. In one embodiment, as the magnetic member 110 moves downwardly with the support platform 46 from a raised position (see FIG. 3A ) and approaches the first end 106 of the bore 104 (see FIG. 4A ), no current flows through the coil 100 and no magnetic forces cooperate with the magnetic field of the magnetic member 110 to induce or hinder motion of the magnetic member 110 . As the lower edge 118 of the magnetic member 110 enters the first end 106 bore of the bore 104 ( FIG. 4B ), current is provided to the coil 100 in a manner that generates a magnetic field that attracts the magnetic member 110 , causing the magnetic member 110 to be drawn into the bore 104 through the interaction of the magnetic fields of the magnetic member 110 and the coil 100 . The coil 100 remains energized as the magnetic member 110 moves into the bore 104 . Just before the lower edge 118 of the magnetic member 110 exits the second end 108 of the bore 104 ( FIG. 4C ), the coil 100 is de-energized to allow the magnetic member 110 to continue moving in a downward direction without the influence of any magnetic field from the coil 100 . Just after the lower end 118 of the magnetic member 110 exits the second end 108 of the bore 104 ( FIG. 4D ), the coil 100 is energized with current in a direction to generate a repulsing magnetic field in the coil 100 that pushes the magnetic member 110 further outside of the second end 108 of the bore 104 . Just as the upper end 120 of the magnetic member 110 exits the second end 108 of the bore 104 , the coil 100 is again de-energized and the magnetic member 110 is allowed to continue moving in a downward direction with no magnetic forces applied by the coil 100 . As the magnetic member 110 continues moving in a downward direction, the spiral torsion spring 60 is deflected by the corresponding downward movement of the support platform 46 until the spring force created by deflecting the spiral torsion spring 60 balances and gradually overcomes the downward inertial force of the loaded platform 46 , and the platform 46 begins to move in the opposite direction, upwardly away from the ground surface. Now, as the upper end 120 of the magnetic member 110 approaches the second end 108 of the bore 104 ( FIG. 4E ), no current is flowing through the coil 100 to create magnetic field lines that cooperate with the magnetic field lines of the magnetic member 110 . As the upper end 120 of the magnetic member 110 enters the second end 108 of the bore 104 ( FIG. 4F ), the coil 100 is energized to generate an attractive magnetic force that interacts with the magnetic field of the magnetic member 110 to thereby draw the magnetic member 110 into the bore 104 . The magnetic member 110 continues moving in an upward direction. Just prior to the upper end 120 of the magnetic member 110 exiting the first end 106 of the bore 104 , the coil 100 is de-energized to permit the magnetic member 110 to move upwardly, unhindered by any magnetic field generated by the coil 100 . Just after the upper end 120 of the magnetic member 110 exits the first end 106 of the bore 104 , the coil 100 is energized with current flowing in a direction that generates a repulsive force that interacts with the magnetic field of the magnetic member 110 , thereby pushing the magnetic member 110 further outside the first end 106 of the bore 104 . Just prior to the lower end 118 of the magnetic member 110 exiting the first end 106 of the bore 104 , the coil 100 is de-energized so that the magnetic field generated by the coil 100 is ceased. The magnetic member 110 continues to move in an upward direction with the support platform 46 until the forces acting on the support platform 46 due to inertia, gravity, spiral torsion spring 60 , and the load carried by the support platform 60 balance out, whereafter the support platform 46 and magnetic member 110 will begin to move downwardly toward the magnetic coil 100 . The control 114 continuously cycles current through the magnetic coil 100 in the manner described above and the motion described above is repeated so that the vertical reciprocating motion of the loaded platform 46 is maintained. The magnetic drive 12 described above is particularly useful when the driven system operates at its natural frequency because a minimum amount of force is needed to be generated by the magnetic drive 12 (to overcome friction losses, for example) whereby the cyclical motion may be maintained with the minimum force applied by the drive 12 . In the embodiment shown, the natural frequency of the loaded support platform 46 may be selectively adjusted by manipulating the roller 80 along the spring lever 66 . As the support platform 46 moves upwardly and downwardly in a reciprocating fashion at the system's natural frequency the magnetic member 110 will be caused to move into and out of the coil 100 as described above, whereby the magnetic drive 12 will maintain the substantially vertical reciprocating motion. Energization of the coil 100 can be automatically adjusted by the control 114 to accommodate variations in natural frequency. In the embodiment shown, the magnetic drive 12 includes a sensor 120 ( FIGS. 1 , 2 , and 5 ) that detects the position of the magnetic member 110 relative to the electric coil 100 and provides signals to the control 114 to energize and de-energize the electric coil 100 in the manner described above. In this embodiment, the sensor 120 comprises an optical position sensor 122 operatively coupled to the frame 16 , and a position indicating member 124 coupled to the support platform 46 (see FIG. 5 ). As the support platform 46 is reciprocated in a substantially vertical direction, the position indicating member 124 is caused to pass by the optical position sensor 122 . When the optical position sensor 122 senses the presence of the position indicating member 124 , signals are provided to the control 114 and the control 114 responds by energizing and de-energizing the electric coil 100 to operate in the manner described above. The control 114 may also be configured to automatically turn the apparatus on and off, by selectively energizing and de-energizing the electric coil 100 . For example, the control 114 may be configured to discontinue energization of the electric coil 100 after a predetermined period of continuous operation, or alternatively after a continuous period of non-use. The control 114 may also be configured such that energization of the electric coil 100 is ceased if no signal is received from the sensor 120 . With such a configuration, the vertical reciprocating motion of the support platform may be stopped simply by holding the platform at a fixed position, either near the uppermost point of travel, or the lowermost point of travel, to thereby prevent the sensor 120 from sending a signal to the control 114 . In a similar fashion, the control 114 may be configured to automatically energize the electric coil 100 at the instant the control receives a signal from the sensor 120 after a period of continuous non-use. When the magnetic drive 12 is used with a system that is configured to operate at its resonance frequency, such as the apparatus 10 described above, and the system further includes a control 114 as described above, a minimum amount of power is required to maintain operation of the system. Moreover, power is conserved by the ability of the control 114 to automatically turn the drive 12 on and off as needed. In an exemplary embodiment, an apparatus 10 for reciprocating an infant support 54 may be powered by six D-cell batteries and may operate continuously for more than approximately 120 hours. While the present invention has been illustrated by the description of an embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.

In one embodiment, a system for providing cyclic motion includes a magnetic drive having an electrically conductive coil defining a bore and a magnetic member movable through the bore. A control provides current to the coil and selectively reverses the direction of the current to move the magnetic member through the bore. In another embodiment, the system includes a counterbalance. The counterbalance includes a biasing member for reacting against a load applied to a support, and a lever arm coupled to the biasing member for varying a preload of the biasing member. In another embodiment, the magnetic drive and the counterbalance may be incorporated into an apparatus for reciprocating a person.

RELATED APPLICATIONS [0001] This application claims the benefit of prior Provisional Application Ser. No. 60/672,747 under 35 U.S.C. § 119 (e) and is hereby specifically incorporated by reference in its entirety STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable REFERENCE A “MICROFICHE APPENDIX” [0003] Not Applicable FIELD OF THE INVENTION [0004] This invention relates to an apparatus and method to monitor body temperature. BRIEF SUMMARY OF THE INVENTION [0005] An apparatus is provided that is made of a garment, at least one connector attached to the garment and an electronic transmission module connected to the connector. The connector is configured to receive an electronic transmission module. The electronic transmission module is programmed for wireless transmission. [0006] In one embodiment, the apparatus has a sensor positioned in the garment to obtain a temperature reading of a wearer of the garment. In one embodiment, the apparatus has a means to communicate the temperature reading to the electronic transmission module. In one embodiment, the apparatus has an electronic monitor to remotely receive and control electronic transmission for the electronic transmission module. [0007] In one embodiment, the electronic monitor has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. In one embodiment, the electronic transmission module has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. [0008] In one embodiment, the apparatus has a means to extend the electronic transmission range of the electronic transmission module. In one embodiment, the means to extend the electronic transmission range of the electronic transmission module is a range extender. The range extender has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. [0009] A connector is provided for making an electrical connection upon insertion of the connector into a corresponding receiver. The receiver has a plurality of connection pads. At least one of the connection pads of the receiver is connected to a power source. The connector is made of an extended body which has an insertion portion and non-insertion portion. The non-insertion portion has a plurality of solder points. The insertion portion has a plurality of connecting pads. The connecting pads on the insertion portion of the connector correspond to the connecting pads on the receiver. The connector is also made of at least one wire attached to the solder points, at least one trance connecting the at least one wire to at least one pad of the connector, and at least one looping trace connecting at least two connection pads of the connector. [0010] In one embodiment, the connector has two side members contiguous to the non-insertion portion the body. In an embodiment, the extended body is a printed circuit board. [0011] A method is provided for monitoring the body temperature of an individual. The method consists of the following steps: (a) placing a garment on an individual, wherein the garment has at least one sensor positioned to obtain a body temperature reading of the individual, wherein the garment has a connector configured to receive an electronic transmission module, wherein the electronic transmission module is programmed for electronic transmission; (b) securing an electronic transmission module into the connector which is configured to receive an electronic transmission module; (c) determining a body temperature from the sensor; (d) communicating the body temperature from the individual to an electronic monitor over a local wireless connection, wherein the electronic monitor is configured to remotely receive and control electronic transmission from the electronic transmission module; and (e) displaying the body temperature on the electronic monitor. [0012] In one embodiment, the method comprising the step of extending the electronic transmission range between the electronic transmission module and the electronic monitor with a range extender. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a schematic rear view of a garment to monitor body temperature. [0014] FIG. 2 is a schematic top view of a garment to monitor body temperature. [0015] FIG. 3 is a side view of an electronic transmission module. [0016] FIG. 4 is a side view of an embodiment of a connector to receive an electronic module. [0017] FIG. 5 is a vertical top view of an electronic transmission module. [0018] FIG. 6 shows a schematic view of the assembly process involving an electronic transmission module inserted into a connector to receive an electronic module. [0019] FIG. 7 is a side view of an electronic monitor. [0020] FIG. 8 is a rear view of an electronic monitor. [0021] FIG. 9 is a front view of an electronic monitor. [0022] FIG. 10 is an enlarged view of the connector with a cut away portion showing the printed circuit board. [0023] FIG. 11 is a schematic front view of a range extender. [0024] FIG. 12 is a schematic side view of the range extender. [0025] FIG. 13 is a schematic top view of the range extender. [0026] FIG. 14 is a flow chart of the process to monitor body temperature. [0027] FIG. 15 is a flow chart of the internal workings of the electronic transmission module. [0028] FIG. 16 is a flow chart of the internal workings of the electronic monitor. DETAILED DESCRIPTION OF THE INVENTION [0029] Referring to FIGS. 1-9 , an embodiment of apparatus 1 to monitor body temperature is disclosed. The apparatus 1 is made of garment 2 , connector to receive an electronic transmission module 4 , electronic transmission module 6 , and electronic monitor 8 . [0030] Referring now to FIGS. 1-2 , garment 2 can be made of any material that will allow garment 2 to fit snuggly against the body of the wearer. Spandex is one example of a material, however other materials, such as a polyester elastane blend, may be used as desired by one of skill in the art. The material of garment 2 has elasticity properties that keep it close to the body of the wearer and such properties prevent garment 2 from stretching out and loosing its conformity to the body. [0031] In one embodiment, garment 2 has thermal sensors 12 sewn into garment 2 in such a way that the sensors 12 are held in close proximity to the body in the area of the underarms. In one embodiment, the sensors 12 are General Electric MA 100™ (GE Thermometrics, Inc. Billerica, Mass.) thermistors but any other sensors that are capable of measuring temperature changes can be used as desired by one of skill in the art. In an embodiment, garment 2 has two sensors 12 but any number of sensors can be used, including one, as desired by one of ordinary skill in the art. In one embodiment, sensors 12 are encased in garment 2 in the area of the underarms, however, sensors 12 may be placed at other locations where such sensors can obtain temperature reading as desired by one of skill in the art. [0032] Two connection wires 68 are connected to each sensor 12 . Connection wires 68 are encased in garment 2 in such a way that the each wire 68 travels from the sensor 12 to the connector 4 . In one embodiment, connection wires 68 travel and are encased along the seams of garment 2 . Garment 2 has antenna 3 appropriate to allow electronic transmission between electronic transmission module 6 and electronic monitor 8 . Antenna 3 is located in the collar of garment 2 . Antenna 3 is appropriate to the IEEE 802.15.4 Standard. [0033] Referring to FIGS. 1-2 and 10 , connector 4 is fixedly attached to garment 2 . In one embodiment, connector 4 is located in pocket 5 located near the collar of garment 2 . Connector 4 is attached to garment 2 by sewing connector 4 to garment 2 . Connector 4 has sewing holes 48 for such attachment (See FIG. 6 ). Other forms of attaching connector 4 may be used as desired by one of skill in the art. In one embodiment, connector 4 is attached to the top shoulder area of garment 2 near the collar but connector 4 can be attached to garment 2 anywhere as desired by one of ordinary skill in the art. Connector 4 is made of a sturdy, water resistant material such as a polymer or plastic but other materials may be used as desired by one of ordinary skill in the art. [0034] Referring now to FIG. 10 , a cut away view of connector 4 is shown. Connector 4 has the size and connection specifications of the male portion of the Micro SD. Other size and connection specification may be used as desired by one of ordinary skill in the art. Connector 4 does not contain an electronic data storage device as contained in the Micro SD. Instead connector 4 is configured to allow connector 4 to make an electrical connection with module 6 upon assembly of module 6 and connector 4 . Connector 4 has an extended body 50 that allows for the physical attachment of connector 4 to receiver 74 of module 6 . (See FIG. 6 ). In one embodiment, connector 4 has side members 52 that allow connector 4 to be attached to another object, such as garment 2 . Body 50 of connector 4 has an insertion portion 54 and a non-insertion portion 56 . Housing 70 covers and protects connector 4 ; however, the connection pads 60 of body 50 are not covered by housing 70 . Connection pads 60 are at the front connection edge of connector 4 . Housing 70 is made of a sturdy, water resistant material such as a polymer or plastic but other materials may be used as desired by one of ordinary skill in the art. Insertion portion 54 has eight connection pads or tabs 60 . Connection pads 60 are metallic connectors. In one embodiment, two of the connection pads 60 are connected by a looping trace 64 . Non-insertion portion 56 has solder points 58 . In one embodiment, five wires 68 are attached to five solder points 58 of non-insertion portion 56 . Traces 62 connect connection wires 68 to connection pads 60 . In one embodiment, connector 4 has snap tabs 76 that snap into snap notches 78 when connector 4 and module 6 are assembled thus reinforcing the assembly between connector 4 and module 6 . [0035] Referring to FIGS. 3 and 6 , module 6 has a receiver 74 . Receiver 74 is reversibly connected to module 6 . Receiver 74 has the size and connection specifications of the female portion of the Micro SD. Other size and connection specifications may be used as desired by one of ordinary skill in the art. Receiver 74 has eight connection pads that correspond to the connection pads 60 of connector 4 . Connection pads of receiver 74 are metallic. Receiver 74 is connected to power supply 20 . [0036] Referring again to FIG. 10 , body 50 is a printed circuit board 66 . In one embodiment, the printed circuit board 66 has five connection wires 68 permanently affixed to board 66 . Two wires 68 (one receiving wire and one transmitting wire) connect to one sensor 12 , two wires 68 (one receiving wire and one transmitting wire) connect to a second sensor 12 , and one wire which connects to antennae 3 that enables the electronic transmission module 6 to transmit information to electronic monitor 8 . The connection wires 68 are insulated except at the point of attachment to board 66 . Housing 70 encases wires 68 as wires 68 exit connector 4 so that moisture is kept out of the internal workings of connector 4 . [0037] Referring now to FIGS. 1-2 , 3 , 5 and 6 , apparatus 1 has an electronic transmission module 6 that connects to connector 4 . Electronic transmission module 6 contains a device 17 that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard or to the ZigBee Protocol. ZigBee is a published specification set of high level communication protocols designed to use small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks. In one embodiment, electronic transmission module 6 is a ZigBee End Device. Pursuant to ZigBee Protocol, module 6 has the functional capabilities to communicate with monitor 8 . In one embodiment, module 6 cannot relay data from other ZigBee devices. In another embodiment, module 6 can relay data from other ZigBee devices, wherein module 6 serves as a ZigBee Router Device. [0038] Device 17 of module 6 contains a radio and a microprocessor which contains the code that enables sensor 12 to constantly measure the temperature of the individual wearing garment 2 upon assembly of module 6 into connector 4 . The microprocessor within device 17 also contains the code that enables the radio of device 17 to function within the specification set forth by the ZigBee 1.0 specifications and subsequent developed versions of such specifications. Electronic transmission module 6 has a power supply 20 (See FIG. 3 ). In one embodiment, power supply 20 is a battery. [0039] Upon assembly of module 6 and connector 4 , eight connection pads 60 of connector 4 line up and connect to eight connection pads located in receiver 74 of module 6 . One of the pads located inside receiver 74 is connected to the power supply 20 of module 6 . This connection is accomplished by a printed circuit board trace between such connection pad inside receiver 74 and power supply 20 . The terminal of power supply 20 is affixed to a point on the printed circuit board inside module 6 . This physical connection allows the electrical current from the power supply 20 to flow from the power supply 20 to such connection pad inside receiver 74 . The electrical current then passes from the pad inside receiver 74 to the corresponding connection pad 60 on connector 4 . The corresponding connection pad 60 on connector 4 has a looping trace 64 connecting such pad 60 to a second connection pad 60 located on connector 4 , thus connecting second connection pad 60 and the corresponding pad inside receiver 74 connected to power-in trace creating a power circuit that allows all electronic components of the module 6 to operate. [0040] Upon assembly of the module 6 and connector 4 , an electrical connection turns module 6 “on” and module 6 sends out a signal to electrical monitor 8 (described below). The electrical connection also enables module 6 to communicate with sensors 12 directing sensors 12 to measure the temperature of the body of the wearer of garment 2 . The electrical connection also enables module 6 to make the connection to antenna 3 which allows the module 6 to transmit electronic communication to the electronic monitor 8 . [0041] Referring now to FIGS. 7-9 , apparatus 1 has an electronic monitor 8 that is configured to remotely receive and control electronic transmission from electronic transmission module 6 . Electronic monitor 8 has a radio that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. Electronic monitor 8 has a microprocessor that operates in accordance with ZigBee 1.0 specifications and subsequently developed versions of such specifications. The ZigBee specifications dictate the communications received and controlled by electronic monitor 8 . [0042] Monitor 8 serves as a Coordinator Device in the ZigBee Mesh Network. Electronic monitor 8 will dictate the frequency of temperature readings and transmissions from the electronic transmission module 6 . Monitor 8 has frequency control option 27 . Electronic monitor 8 contains code that allows the user of apparatus 1 to setup parameters of temperature profiles that trigger audible and visible alarms set off by the electronic monitor 8 when those parameters are met or exceeded. Monitor 8 has alarm control option 26 . Electronic monitor 8 may also contain code that initiates other message activities over the public or a private telephone network, radio or intercom network as well as create messages for electronic communications such as email. [0043] Monitor 8 contains code that allows the temperature readings to be recorded to flash memory for later retrieval through a port or by removal of the flash device. In one embodiment, a USB port 36 is used to retrieve temperature readings but any other port can be used as desired by one of ordinary skill in the art (See FIG. 7 ). [0044] Monitor 8 may communicate with more than one electronic transmission module 6 inserted into the connector 4 of two garments 2 within its Mesh Network. Referring to FIG. 9 , monitor 8 has two temperature reading displays 38 . Monitor 8 has two charging circuits 34 for recharging electronic transmission module 6 (See FIG. 9 ). In one embodiment, monitor 8 has an alarm suspend 30 and clock 40 . Monitor 8 has a commercial plug attachment 28 built into it allowing the user to plug the monitor 8 into commercial power. [0045] Referring now to FIGS. 11-12 , in one embodiment, apparatus 1 has a range extender 10 that extends the electronic transmission range of the electronic transmission module 6 . If module 6 and monitor 8 exceed the operable range, appropriate to the IEEE 802.15.4 Standard, the range extender 10 can be used to extend the range and allow the apparatus 1 to function. The range extender 10 has a radio 16 that conforms to IEEE 802.15.4 Low Rate Wireless Personal Area Standard and range extender 10 has a microprocessor 18 coded with ZigBee 1.0 specifications and subsequently developed specifications. The range extender 10 serves as a ZigBee router. Range extender 10 is connected to a power supply through outlet 19 and has antenna 21 . Antenna 21 is connected to extender 10 by hinge 23 . Antenna 21 is appropriate to the IEEE 802.15.4 Standard. The radio in the range extender 10 follows the ZigBee protocols under the “Router” functional specification. The range extender 10 allows electronic transmission module 6 to be bridged to electronic monitor 8 if it is out of range or if some other force precludes the proper communication between the electronic transmission module 6 and electronic monitor 8 . [0046] Referring now to FIG. 14 with reference to FIGS. 1-10 , the overall process of monitoring body temperature of an individual is provided. Module 6 is removed from charging circuit or unit 34 . Module 6 is snapped into connector 4 . Upon assembly, module 6 communicates with monitor 8 and module 6 begins operating according to firmware or code. Module 6 causes sensor 12 to return a reading of resistance which is converted to a temperature equivalent. Module 6 transmits the temperature reading to monitor 8 which displays or announces the temperature. Monitor 8 compares the display with a potentially pre-set alarm point. If the pre-set alarm point is reached, monitor 8 will sound an alarm and/or vibrate. Monitor 8 records the temperature data in a memory buffer which can be downloaded into other storage devices via the port on monitor 8 . Module 6 is removed from the connector 4 and re-attached to charging circuit or unit 34 on monitor 8 for charging. The process can be started again once module 6 is recharged. [0047] Referring now to FIG. 15 with reference to FIGS. 1-10 , the internal workings of the electronic transmission module 6 are provided. Module 6 is snapped into connector 4 which has looping trace 64 that enables module 6 to operate. Module 6 sends out a beacon request to announce its presence to monitor 8 . Module 6 sends its MAC address to monitor 8 for verification. Module 6 receives validation to operate on network. Module 6 launches operating firmware routine for temperature measurement. Firmware causes printed circuit board components to release electrical current into one wire of sensor 12 . Sensor 12 changes size based on the surrounding temperature. The size change of sensor 12 creates measurable electrical resistance. The resistance is measured as the electrical current is returned to module 6 through the second wire of the sensor. The electrical resistance is measured by virtue of an ADC port on the printed circuit board. The ADC value is compared to an “R to T” chart for sensor 12 . The corresponding temperature found in the “R to T” chart is transmitted to monitor 8 via the 802.15.4 radio. [0048] Referring now to FIG. 16 with reference to FIGS. 1-10 , the internal workings of the electronic monitor 8 are provided. Monitor 8 is plugged into commercial power and/or batteries are installed. After module 6 is charged, module 6 is removed from charging circuit 34 and snapped into connector 4 . Alarm values are set via adjustment buttons on the outside of monitor 8 . Monitor 8 establishes connection with module 6 . The firmware causes the 802.15.4 radio to accept communication that conforms to the correct protocol. The monitor 8 receives data from module 6 . The firmware causes the display to show the corresponding value. Monitor 8 displays the temperature value. An alarm is sounded if the display values are equal to or greater than the alarm values. The display values are recorded in a memory buffer for later retrieval. An outside storage device can be attached to the port on monitor 8 to extract the stored data. [0049] Although the foregoing detailed description has been set forth in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications can be made within the full scope of the invention.

An apparatus is provided which is made of a garment having at least one connector to receive an electronic transmission module and an electronic monitor configured to remotely receive and control electronic transmission from the electronic transmission module. The garment includes a sensor to detect the temperature of the wearer. This invention also provides a connector for making an electrical connection. This invention also provides a method for monitoring the body temperature of the wearer.

BACKGROUND OF THE INVENTION 1. Field of the Invention. The invention concerns a system for the hydraulic control of a clutch. The invention concerns more particularly a system for the hydraulic control of a clutch, in particular for a motor vehicle, comprising an upstream sending cylinder connected by a conduit to a downstream receiving cylinder so as to form a hydraulic control circuit. 2. Description of the Related Art. It is sometimes desirable to equip the hydraulic control system for a clutch with an assistance device so as to minimise the force that the user has to apply to the clutch control pedal during the declutching phase. Such a device is described for example in the document US-B-6.213.271. In this document, the assistance device is mounted on the sending cylinder of the hydraulic clutch control system. This system has the drawback of requiring a specific sending cylinder adapted to the arrangement of the supplementary elements fulfilling the assistance function. The arrangement of the supplementary elements on the sending cylinder poses problems of space requirements and this makes the sending cylinder more complex to produce. SUMMARY OF THE INVENTION The present invention aims to remedy these drawbacks by proposing a simple and economical solution that does not require modifying the sending cylinder or receiving cylinder. For this purpose, the invention proposes a control system of the type described above, characterised in that it comprises an assistance cylinder that is interposed in the conduit, between the sending cylinder and the receiving cylinder, and which comprises at least one assistance piston that is mounted so as to slide axially in the body of the assistance cylinder between an upstream engagement position and a downstream disengagement position, so as to delimit an upstream hydraulic chamber and a downstream hydraulic chamber with variable volumes according to the axial position of the piston, the upstream chamber being connected to the sending cylinder by a portion of hydraulic circuit referred to the upstream circuit and the downstream chamber being connected to the receiving cylinder by a portion of the hydraulic circuit referred to as the downstream circuit, each hydraulic circuit portion comprising a means of relevelling the volume of fluid connected to at least one fluid reservoir, and in that the assistance cylinder comprises an assistance device that applies an assistance force to the assistance piston during the declutching phase. One advantage of the system according to the invention is that it uses a sending cylinder and receiving cylinder of a standard type, which have not been designed to be equipped with an assistance device. In addition, the clutch control system according to the invention can be arranged in a vehicle without its being necessary to modify the area where the sending cylinder is arranged and/or the area where the receiving cylinder is arranged, compared with a similar vehicle not equipped with the assistance device, the space requirement of the sending cylinder and the space requirement of the receiving cylinder not being modified. Another advantage of the control system according to the invention is that the assistance cylinder and its assistance device do not have any influence on the control law linking the movement of the clutch control pedal to the movement to the movement of the clutch diaphragm. The position of the diaphragm is therefore always dependent on the position of the pedal. Yet another advantage of the control system according to the invention is that, as the two upstream and downstream circuits have a means of relevelling the volume of fluid, the system keeps a constant operating point whatever the variations in the position of the clutch, variations which may stem for example from wear on the clutch, heating thereof, or the control of the clutch. According to other characteristics of the invention: the assistance device comprises a regulation means which makes the value of the assistance force vary according to the travel of the clutch control pedal in accordance with a predetermined assistance law; the assistance device comprises a transmission member which transmits the assistance force to the assistance piston; the transmission member is connected in terms of axial movement to the assistance piston in both directions of sliding of the piston; the transmission member cooperates by contact with an associated abutment surface of the assistance piston so that, in the case where the speed of the assistance device is less than the speed of the assistance piston, the assistance device does not slow down the sliding of the assistance piston towards the downstream end; the transmission member is arranged at an axial end of the assistance piston; the piston comprises an upstream portion that delimits the upstream chamber and a downstream portion that delimits the downstream chamber, the two portions being connected in axial movement by a connecting rod, and the connecting rod constitutes the transmission member of the assistance device; the hydraulic circuit being connected to a fluid reservoir in the engagement position, the assistance cylinder comprises at least one discharge orifice which makes at least one hydraulic chamber communicate with the fluid reservoir, when the assistance piston is occupying its upstream position, so as to compensate for the variations in hydraulic volume in the hydraulic circuit over time; the discharge orifice is arranged in the assistance piston and the discharge orifice makes the upstream chamber communicate with the downstream chamber, when the assistance piston is occupying its upstream position; the discharge orifice comprises a valve that is controlled by the axial movement of the assistance piston; the assistance device comprises an elastic element which stores energy during the engagement phase and which restores the energy during the disengagement phase in order to produce the assistance force; the regulation means is a cam mechanism which is driven by the axial movement of the piston and which regulates the assistance force produced by the elastic element during the disengagement phase; the assistance device is housed in the cylinder body and the cam mechanism comprises at least one control surface that is produced on an internal wall of the cylinder body; the elastic assistance element is an axial compression elastic element that is interposed axially between a cup and an abutment surface fixed with respect to the assistance cylinder body, the cam mechanism comprises at least one movable roller which travels over a control surface between an upstream position and a downstream position corresponding respectively to the upstream and downstream positions of the assistance piston, and the movable roller is connected by a first connecting rod to the piston by a second connecting rod to the cup; the axis by which the connecting rods pivot on the movable roller is concurrent with the rotation axis of the roller; the control surface comprises an upstream portion inclined with respect to the sliding axis, and a downstream portion roughly parallel to the sliding axis so that, during a first part of the disengagement phase, the movable roller moves first of all on the inclined portion towards the axis and in the downstream direction, from its upstream position, transmitting part of the relaxation force of the elastic assistance element to the assistance piston, by a step-down effect, and then, during a second part of the disengagement phase, the movable roller moves on the downstream portion in the downstream direction, in a roughly axial direction, transmitting all the relaxation force of the elastic assistance element to the assistance piston; the distance between the pivot axes of the second connecting rod is such that, in the upstream position of the movable roller, the roller moves in the upstream direction beyond the point on the control surface where the second connecting rod is perpendicular to the control surface, so that the expansion force of the elastic assistance element biases the movement roller towards its upstream position; the axial dimension of the elastic assistance force in the relaxed state is less than the axial distance between the cup and the associated fixed abutment surface, when the piston occupies its downstream position, so as to suspend the assistance force during the end of the travel of the piston in the downstream direction; the assistance device comprises an electrical actuator that controls the relaxation of the elastic element during the disengagement phase; the means of regulating the assistance device is an electronic control unit that controls the electrical actuator; the elastic assistance element is a helical compression spring; the assistance device is connected to an energy source that is external to the control system and that is installed in the vehicle that the control system equips, and the said energy produces the assistance force that is transmitted to the piston; the assistance device comprises an electrical actuator controlled so as to transmit an assistance force to the piston during the disengagement phase; the means of regulating the assistance device is an electronic control unit that controls the electrical actuator producing the assistance force; the assistance device comprises a ram that is connected to a hydraulic or pneumatic pressure source and that transmits an assistance force to the piston during the disengagement phase; the means of regulating the assistance device comprises at least one control valve interposed between the ram and the hydraulic or pneumatic pressure source; the regulation means comprises a two-position control valve connected to a pressure source in order to form a charging valve and a two-position control valve connected to a fluid reservoir in order to form a discharge valve, and each control valve is controlled by the hydraulic pressure in the upstream circuit, so that the hydraulic pressure in the upstream circuit tends towards a first constant value during a disengagement travel and tends towards a second constant value, less than the first value, during an engagement travel; the regulation means comprises a three-position control valve, a charging position that is connected to a pressure source, an intermediate closure position, and a discharge position connected to a fluid reservoir, and the control valve is controlled, on the charging position side, by the hydraulic pressure in the upstream circuit and, on the discharge position side, by the hydraulic pressure in the downstream circuit, so that the assistance force applied to the assistance piston during the disengagement phase is proportional to the hydraulic pressure in the downstream circuit; the distributor is controlled by an electronic control unit; the piston comprises at least one elastic element that returns the piston towards its upstream position. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will emerge from a reading of the following detailed description, for an understanding of which reference will be made to the accompanying drawings, in which: FIG. 1 is a diagram representing a hydraulic clutch control system produced in accordance with the teachings of the invention; FIGS. 2 and 3 illustrate schematically the operating principle of the assistance in the control system according to the invention; FIG. 4 is a diagram similar to that of FIG. 2 that illustrates a variant embodiment of the dumping to reservoir of the hydraulic control circuits; FIG. 5 is a view in axial section depicting schematically the assistance of the control system according to a first embodiment of the invention in which the assistance device comprises a cam mechanism, the piston being shown respectively in its upstream position and in its downstream position; FIGS. 6 and 7 are partial views in axial section which depict a detail of FIG. 5 and which illustrate two successive intermediate positions of a movable roller equipping the cam mechanism; FIG. 8 is a diagram illustrating the change in hydraulic pressure in the control circuit and the change in the assistance force according to the travel of the clutch pedal; FIG. 9 is a view similar to that of FIG. 5 depicting schematically an assistance cylinder according to a second embodiment in which the assistance device is arranged at the upstream end of the assistance cylinder; FIG. 10 is a diagram similar to that in FIG. 2 that depicts schematically a control system according to a third embodiment of the invention in which the relaxation of the assistance spring is controlled by an electrical actuator; FIG. 11 is a diagram similar to that of FIG. 9 that depicts an assistance cylinder according to a fourth embodiment of the control system according to the invention in which the assistance force is produced by an electric motor; FIG. 12 is a diagram similar to that of FIG. 2 that depicts schematically a control system according to a fifth embodiment of the invention in which the assistance force is produced by a ram connected to a pressure source; FIG. 13 is a view in axial section that depicts an assistance cylinder adapted to the control system of FIG. 12 and comprising a membrane ram; FIGS. 14 , 16 and 18 are diagrams similar to that in FIG. 2 that illustrate three different solutions for regulating the assistance force adapted to the control system of FIG. 12 ; FIGS. 15 and 17 are diagrams illustrating the assistance laws associated respectively with the first two solutions depicted in FIGS. 14 and 16 ; FIG. 19 is a view in axial section depicting a variant of the embodiment in FIG. 13 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, identical, similar or analogous elements will be designated by the same reference numbers. FIG. 1 depicts a hydraulic control system 10 of a motor vehicle clutch 12 produced in accordance with the teachings of the invention. The control system 10 comprises an upstream sending cylinder 14 connected by a pipe or conduit 16 to a downstream receiving cylinder 18 with a similar structure to the sending cylinder 14 . The sending cylinder 14 , the receiving cylinder 18 and the conduit 16 form a hydraulic control circuit 19 . Each sending 14 or receiving 18 cylinder comprises a piston (not shown) able to move axially inside a cylinder body in order to delimit a hydraulic chamber of variable volume. A connection orifice, to which the conduit 16 is connected, opens out in the hydraulic chamber. The sending cylinder 14 comprises a piston rod 20 connected here to a clutch pedal 22 on which the driver of the vehicle acts. The piston of the sending cylinder 14 is designed to expel a control fluid or liquid contained in the hydraulic chamber in the direction of the conduit 16 , during a declutching operation. When the clutch 12 is engaged, the volume of the hydraulic chamber of the sending cylinder 14 is at a maximum whilst the volume of the hydraulic chamber of the receiving cylinder 18 is at a minimum. During the declutching operation, the volume of the hydraulic chamber of the sending cylinder 14 decreases, whilst the volume of the hydraulic chamber of the receiving cylinder 18 increases. The piston of the receiving cylinder 18 then causes the movement of a rod 24 , which acts here on a declutching fork 26 actuating a clutch release bearing 28 . When the driver releases his action on the clutch pedal 22 , the piston of the receiving cylinder 18 is returned towards its initial position by a clutch spring such as a diaphragm 13 . In returning to its initial position, the receiving cylinder 18 pushes the column of oil contained in the hydraulic circuit 19 , which causes the return of the piston of the sending cylinder 14 to its initial position. The clutch pedal 22 is returned to its initial position by a return spring and/or by the return of the piston of the sending cylinder 14 . Generally, each sending 14 and receiving 18 cylinder comprises a spring (not shown) which acts between the piston and the bottom of the body of the cylinder, and which guarantees the return of the piston as far as its initial position in abutment. Preferably, the hydraulic chamber of the sending cylinder 14 is able to be connected to a fluid reservoir 29 , so as to compensate for the variations in volume of the hydraulic circuit 19 over time. To this end, the hydraulic chamber of the sending cylinder 14 comprises at least one discharge orifice (not shown) which is open when the sending piston returns completely to its initial position and which makes the hydraulic circuit 19 communicate with the reservoir 29 . It should be noted that, during the declutching phase, the pedal 22 has dead travel at the start of its pivoting, which corresponds to a movement of the sending piston as far as the axial position in which it closes the discharge orifice. During the dead travel, the sending piston pushes the fluid towards the reservoir 29 , without causing the movement of the receiving piston. In accordance with the teachings of the invention, the control system 10 comprises an assistance cylinder 30 interposed in the conduit 16 , between the sending cylinder 14 and the receiving cylinder 18 . FIG. 2 depicts the control system 10 according to the invention in an simplified manner. It should be noted that, in this figure, the rod 24 of the receiving piston acts directly on the diaphragm 13 of the clutch 12 by means of a bearing comprising a ball bearing (not shown). The assistance cylinder 30 comprises an assistance piston 32 mounted so as to slide along a principal axis A 1 , between an upstream position and a downstream position, so as to delimit an upstream hydraulic chamber 34 and a downstream hydraulic chamber 36 with variable volumes according to the axial position of the piston 32 . The upstream chamber 34 communicates with the chamber 38 of the sending cylinder 14 by means of an upstream portion 40 of the hydraulic circuit 19 , and the downstream chamber communicates with the chamber 42 of the receiving cylinder 18 by means of a downstream portion 44 of the hydraulic circuit 19 . The upstream hydraulic circuit 40 is connected to the fluid reservoir 29 at the sending chamber 38 . The downstream hydraulic circuit 44 is connected to a fluid reservoir, for example the same reservoir 29 as the upstream hydraulic circuit 40 , here at the downstream chamber 36 of the assistance cylinder 30 . According to the embodiment illustrated here, the assistance cylinder 30 comprises a spring 46 which is interposed axially between the assistance piston 32 and the bottom of the downstream chamber 36 , and which returns the assistance piston 32 towards its upstream position. In the diagram, the assistance piston 32 comprises a rod 48 which extends towards the outside through the upstream chamber 34 . According to a variant (not shown), the assistance cylinder 30 with its piston 32 can be replaced by a chamber comprising an intermediate membrane separating the upstream 34 and downstream 36 chambers and fulfilling the role of the assistance piston 32 . This membrane in the same way comprises the rod 48 . In accordance with the teachings of the invention, during the declutching phase, which is illustrated by FIG. 3 , an assistance force F a is applied to the assistance piston 32 , here by means of the rod 48 , so as to relieve the abutment force F p of the user on the pedal 22 . The assistance force F a is produced by an assistance device 50 which will be described hereinafter. According to a variant embodiment depicted in FIG. 4 , a discharge orifice 52 is produced in the assistance piston 32 , so as to make the upstream hydraulic circuit 40 communicate with the downstream hydraulic circuit 44 when the piston 32 is occupying its upstream position. According to the diagram in FIG. 4 , the discharge orifice 32 passes axially through the piston 32 and comprises a discharge valve 54 which is biased elastically towards its closure position and which opens mechanically when the assistance piston 32 comes to occupy its upstream position, by the abutment of a rod of the valve 42 on the bottom of the upstream chamber 34 . The arrangement of the discharge orifice 52 in the piston 32 makes it possible in particular to connect the entire hydraulic circuit 19 to the fluid reservoir 29 , with a single connection, arranged here at the sending cylinder 14 . This arrangement also makes it possible not to add additional dead travel to the clutch pedal 22 , which is the case when the assistance cylinder 30 is connected to the reservoir 29 as in FIG. 2 . The opening of the discharge valve 54 can be calibrated so that an abrupt increase in the hydraulic pressure in the sending chamber 38 causes, almost immediately, a movement of the assistance piston 32 in the downstream direction, the fluid not having the time to flow through the discharge valve 34 , and therefore the closure of the discharge orifice 52 . This calibration can make it possible to choose the value of the first axial travel of the assistance piston 32 in the downstream direction, before the assistance device 50 has begun to apply an assistance force F a . A description is now given of a first embodiment of the control system 10 according to the invention which is shown in FIGS. 5 to 7 , in which the assistance device 50 comprises an elastic element which stores energy during the engagement phase and which restores the energy, in the form of an assistance force F a , during the disengagement phase. According to the first embodiment, the assistance cylinder 30 comprises a cylinder body 56 which is provided with an inlet orifice 58 and a discharge orifice 60 . The assistance piston 32 is mounted so as to slide, along the principal axis A 1 within the cylinder body 56 , which has roughly a tubular shape of axis A 1 . In the remainder of the description, elements will be termed internal or external with respect to the principal axis A 1 in a radial direction. Considering FIG. 5 , the piston 32 is shown in the upstream position on the top half section and in the downstream position on the bottom half section. The upstream chamber 34 communicates with the sending cylinder 14 through the inlet orifice 58 , and the downstream chamber 36 communicates with the receiving cylinder 18 through the discharge orifice 60 . According to the embodiment depicted here, the assistance piston 32 is produced in several parts. The piston 32 comprises an upstream portion 62 , which is designed to slide axially in a complementary upstream bore 64 , and a downstream portion 66 which is designed to slide axially in a complementary downstream bore 68 , the two portions 62 , 66 being connected with respect to axial movement by an axial connecting rod 70 . The connecting rod 70 comprises here an internal rod 72 , for example made from metal, and an external body 74 moulded onto the internal rod 72 . The upstream end 76 and the downstream end 78 of the rod 70 are each here in the form of a spherical head. The two portions 62 , 66 here have roughly identical shapes. The upstream portion 62 has overall a tubular shape with an H-shaped axial profile, that is to say it has two tubular parts substantially symmetrical with respect to a transverse separation wall 80 . On the side of the upstream face 82 of the transverse wall 80 , the upstream portion 62 forms a jacket 84 which delimits a part of the upstream chamber 34 . On the side of the downstream face 86 of the transverse wall 80 , the upstream portion 62 forms a housing 88 which receives a roughly cylindrical piece 90 forming a receptacle for the connection between the upstream axial end 76 of the connecting rod 70 and the upstream portion 62 of the piston 32 . According to the embodiment depicted here, the downstream portion 66 is substantially similar to the upstream portion 62 and the downstream portion 66 is arranged substantially symmetrically with the upstream portion 62 , with respect to a transverse symmetry plane. Thus the downstream portion 66 has a transverse separation wall 92 and, on the side of the downstream face 94 of this wall 92 , forms a jacket 96 which delimits a part of the downstream chamber 36 . On the side of the upstream face 98 of the transverse wall 92 , the downstream portion 66 receives a cylindrical piece 100 , similar to that of the upstream portion 62 , forming a receptacle for the connection between the downstream axial end 78 of the connecting rod 70 and the downstream portion 66 . In the embodiment shown, the downstream bore 68 has an annular radial groove 102 which communicates with the liquid reservoir 29 , so as to form a discharge orifice. This embodiment therefore corresponds to the embodiment depicted in FIGS. 2 and 3 , in which the downstream circuit 44 comprises a connection to the reservoir 29 at the downstream chamber 36 . The jacket 96 of the downstream portion 66 comprises here several radial orifices 104 which are substantially aligned circumferentially and which are arranged opposite the radial groove 102 , when the piston 32 occupies its upstream position, as depicted in the top half of FIG. 5 . The radial orifices 104 make it possible to put the downstream chamber 36 and the reservoir 29 in communication, when the piston 32 is occupying its upstream position, so as to compensate for the variations in hydraulic volume in the downstream circuit 44 over time. In the downstream position of the piston 32 , as depicted in the bottom half of FIG. 5 , the orifices 104 are offset axially in the downstream direction, with respect to the radial groove 102 , so that the downstream chamber 36 does not communicate with the reservoir 29 . Naturally, as indicated with reference to the variant in FIG. 4 , the radial groove 102 and the radial orifices 104 can be omitted in favour of a discharge orifice 52 produced axially in the piston 32 and provided with a discharge valve 54 . The assistance device 50 comprises here an elastic element in the form of an axial helical compression spring 106 . The spring 106 is designed to compress during the engagement phase, under the effect of the return of the assistance piston 32 to its upstream position, so as to store energy, and is designed to restore this energy during the disengagement phase, producing an assistance force F a . The spring 106 is interposed axially between an axially movable annular cup 108 and a fixed annular radial abutment surface 110 provided in the cylinder body 56 . The cup 108 comprises an annular radial abutment surface 111 which is oriented in the upstream direction and which faces the fixed abutment surface 110 oriented in the downstream direction. The spring 106 is here mounted around an internal tubular guide portion 112 of the cylinder body 56 . The assistance device 50 comprises a cam mechanism 114 which is driven by the axial movement of the piston 32 , and which forms a regulation means 115 for varying the value of the assistance force F a according to the travel C p of the pedal 22 in accordance with a predetermined assistance law. The cam mechanism 114 comprises, for example, two moving rollers 116 , 118 which each travel over an associated control surface 120 , 122 . The two rollers 116 , 118 are here arranged on each side of the piston 32 and are diametrically opposed. The rotation axis A 2 of each roller 116 , 118 is substantially orthogonal to the sliding axis A 1 of the piston 32 . Each roller 116 , 118 is connected by a downstream link 124 to the connecting rod 70 and by an upstream link 126 to the cup 108 . It should be noted that the connecting rod 70 here constitutes a transmission member 71 which enables the assistance device 50 to transmit the assistance force F a to the assistance piston 32 . On the roller 116 , 118 side, the links 124 , 126 are mounted for pivoting about the rotation axis A 2 of the roller 116 , 118 . The downstream link 124 is mounted for pivoting on the free end of an associated transverse arm 128 , 130 of the connection rod 70 . According to the embodiment depicted here, the cylinder body 56 forms an envelope 132 that is roughly cylindrical around the assistance device 50 . The envelope 132 is stepped in diameter. Advantageously, the control surface 120 , 122 associated with each roller 116 , 118 is produced on the internal wall of the envelope 132 . The control surfaces 120 , 122 are here substantially symmetrical with respect to an axial plane (A 1 ) and extend roughly in the same axial plane. Each control surface 120 , 122 comprises an upstream portion 134 inclined with respect to the sliding axis A 1 and a downstream portion 136 roughly parallel to the sliding axis A 1 . The upstream portion 134 has here a rounded profile convex towards the axis A 1 and towards the upstream end. According to an advantageous embodiment, the distance between the pivot axes of each upstream link 126 , 128 is such that, in the upstream position of the associated moving roller 116 , 118 , the roller goes beyond, towards the upstream end, the point B 1 on the control surface 120 , 122 where the upstream link 126 , 128 is perpendicular to the control surface 120 , 122 , so that the relaxing force of the assistance spring 106 biases the moving roller 116 , 118 towards its upstream position. In another advantageous embodiment, when the piston 32 is occupying its downstream declutching position, the axial distance between the abutment surface 111 of the cup 108 and the fixed abutment surface 110 is greater than the axial dimension of the spring 106 in the relaxed state, so that the spring 106 does not axially bias the piston 32 towards its downstream position. The functioning of the cam mechanism 114 according to the invention is now explained, considering in particular the partial positions depicted in FIGS. 6 and 7 and the diagrams depicted in FIG. 8 . On the top part of FIG. 8 , the curve C aval in continuous line represents a change in the hydraulic pressure P h in the downstream chamber of the assistance cylinder 30 , during the declutching phase, as a function of the travel C p of the clutch pedal 22 , and the curve C amont in a broken line represents the change in the hydraulic pressure P h in the upstream chamber of the assistance cylinder 30 during the declutching phase as a function of the travel C p of the clutch pedal 22 . In the bottom part of FIG. 8 , the curve in a continuous line represents the change in the assistance force F a produced by the assistance spring 106 , during the declutching phase, as a function of the travel C p of the clutch pedal 22 , and the straight line in a broken line represents the stiffness of the assistance spring 106 . In the upstream position of the assistance piston 32 , which is illustrated by the top part of FIG. 5 , the spring 106 is compressed and axially biases (A 1 ) each upstream link 126 , as well as the associated roller 116 , 118 , towards the control surface 120 , 122 and towards the outside, without causing any movement of the assistance piston 32 . The moving rollers 116 , 118 are here held by the associated downstream link 124 , which is connected to the assistance piston 32 in the upstream abutment position. At the start of the declutching phase, the user presses on the control pedal 22 of the clutch 12 so as to move the piston of the sending cylinder 14 in the downstream direction. The first part of the movement of the piston of the sending cylinder 14 corresponds to a dead travel, until the discharge orifice connecting the sending chamber 38 to the reservoir 29 closes. Continuing its movement in the downstream direction, the piston of the sending cylinder 14 then causes an increase in the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 , which causes an axial movement A 1 of the assistance piston 32 towards the downstream end. The movement of the assistance piston 32 causes a movement of the rollers 116 , 118 over the associated control surfaces 120 , 122 , towards the inside and towards the downstream direction. During a first phase P 1 of its axial movement, the assistance piston 32 causes an additional compression of the assistance spring 106 , so that the assistance device 50 produces a resistance force which opposes the movement of the clutch pedal 22 , which corresponds to a negative assistance force F a , illustrated by the bottom part of FIG. 8 . During this first phase P 1 , the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 is greater than the hydraulic pressure P h in the downstream chamber 36 . The first phase P 1 of the movement of the piston 32 ends when the rollers 116 , 118 reach the point B 1 on the control surface 120 , 122 where the upstream link 126 , 128 is perpendicular to the control surface 120 , 122 , which is shown in FIG. 6 . At the moment when the rollers 116 , 118 reach this point B 1 of the control surface 120 , 122 , the relaxation force of the assistance spring 106 is cancelled by the reaction force of the control surface 120 , 122 , so that the hydraulic pressure P h equalises between the upstream chamber 34 and the downstream chamber 26 of the assistance cylinder 30 . It should be noted that, during the first phase P 1 , the axial movement of the piston 32 causes the closure of the connection 102 of the downstream chamber 36 with the reservoir 29 , by virtue of the axial offset of the radial orifices 104 in the downstream direction. During a second phase P 2 of the axial movement of the assistance piston 32 in the downstream direction the assistance spring 106 commences to relax, producing an assistance force F a on the assistance piston 32 . The assistance force F a produced by the spring 106 is stepped down by the cam mechanism 114 , according to the profile of the upstream portion 134 of the control surface 120 , 122 , which makes it possible to regulate the assistance force F a according to the travel C p of the pedal 22 , in accordance with a predetermined assistance law. The second phase P 2 of the movement of the piston 32 ends when the rollers 116 , 118 reach the downstream end B 2 of the upstream portion 134 of the associated control surface 120 , 122 , as depicted in FIG. 7 . The assistance piston 32 then begins a third phase P 3 of its axial movement, during which the rollers 116 , 118 travel over the downstream portion 136 of the associated control surface, 120 , 122 . During this third phase P 3 , the assistance spring 106 transmits all its relaxation force to the assistance piston 32 since the links 124 , 126 are no longer pivoting and the rollers 116 , 118 are no longer held axially by the control circuit 120 , 122 . It should be noted that, during the third phase P 3 , the links 124 , 126 can be close to an aligned position but it is preferable to keep a minimum inclination angle between the links 124 , 126 , as in FIG. 7 and on the bottom part of FIG. 5 , so as to cause the links 124 , 126 to pivot, during the return of the assistance piston 32 towards its upstream position, in order to prevent locking of the piston 32 in the cylinder 30 . According to the advantageous embodiment provided here, as the axial distance between the abutment surface 111 of the cup 108 and the fixed abutment surface 110 is greater than the axial dimension of the spring 106 in the relaxed state, the third phase P 3 is followed by a fourth phase P 4 during which the assistance piston 32 continues to slide as far as its downstream abutment position, without benefiting from an assistance force F a since the assistance spring 106 is in the relaxed state. The fourth phase P 4 is useful for minimising the friction forces caused by the assistance device 50 during the movement of the assistance piston 32 , so as to guarantee the return of the piston 32 in the upstream direction, from its downstream position, in particular when the return force of the assistance piston 32 produced, for example, by the diaphragm 13 is small. When the user releases his pressing on the pedal 22 , the return elements of the clutch 12 such as the diaphragm 13 cause the return of the assistance piston 32 in the upstream direction. The return of the piston 32 in the upstream direction causes a return of the cam mechanism 114 into its initial position and a compression of the assistance spring 106 , which enables it to store elastic energy. Preferably, at the end of the travel of the assistance piston 32 in the upstream direction, which corresponds to the first phase P 1 of the movement of the piston 32 in the downstream direction, the assistance spring 106 causes an elastic return of the piston 32 as far as its upstream position, biasing the movable rollers 116 , 118 towards their upstream idle positions. In the upstream position of the piston 32 , the orifices 104 of its downstream portion 66 come to be positioned opposite the radial groove 102 , which connects the downstream hydraulic circuit 44 to the liquid reservoir 29 . FIG. 9 depicts schematically a second embodiment of the control system 10 according to the invention. It should be noted that the representation of the second embodiment has been simplified with respect to the representation of the first embodiment in FIG. 5 . This second embodiment is differentiated from the first mainly by the fact that the assistance device 50 is arranged at the upstream axial end of the assistance cylinder 30 rather than between the two hydraulic chambers 34 , 36 . According to this embodiment, the assistance cylinder 30 comprises a piston 32 whose upstream transverse face 138 delimits the upstream chamber 34 and whose downstream transverse face 140 delimits the downstream chamber 36 . The piston 32 is here produced overall in a single piece. According to the embodiment depicted here, a helical compression spring 142 is interposed axially between a downstream transverse end surface 144 of the piston 32 and the bottom wall 146 of the downstream chamber 36 . This spring 142 serves to guarantee the return of the piston 32 as far as its upstream abutment position. The assistance device 50 is produced in a similar manner to that of the first embodiment. It comprises in particular an assistance spring 106 and a cam mechanism 114 . The assistance device 50 comprises a transmission member 50 in the form of a transmission rod that extends axially towards the upstream transverse face 138 of the assistance piston 32 . According to an advantageous embodiment, depicted here, the transmission rod 71 cooperates solely by contact with the upstream transverse surface 138 of the assistance piston 32 . This configuration of the transmission rod 71 enables the assistance piston 32 to slide independently of the rod 71 . Thus, where the pressure exerted by the assistance device 50 on the transmission rod 71 is less than the pressure exerted on the assistance piston 32 by the fluid contained in the upstream chamber 34 , the assistance piston 32 can slide in the downstream direction without being slowed down by the movement of the assistance device 50 . Such a configuration also mitigates malfunctioning of the assistance device 50 since the control system 10 can function without assistance. FIG. 9 also depicts a variant embodiment of the device for connecting the downstream chamber 36 to the reservoir 29 . Advantageously, the assistance cylinder 30 comprises here a discharge valve 148 which is controlled by the piston 32 , so as to connect to the reservoir 29 when the piston 32 is occupying its upstream position. To this end, the pipe connecting to the reservoir 29 emerges, through a discharge orifice 150 , in an intermediate cylindrical cavity 152 which is arranged at the downstream axial end of the cylinder body 56 . The intermediate cavity 152 communicates with the downstream chamber 36 through an opening 154 that emerges in the bottom wall 146 of the downstream chamber 36 . The valve 148 comprises a rod or tail 156 which is provided, at its downstream axial end, with a head 158 able to close off the communication orifice 150 , and at its upstream axial end with a control collar 160 delimiting a transverse abutment surface 162 oriented in the downstream direction. The valve 148 is biased axially in the downstream direction and therefore towards the closure position of the discharge orifice 150 , by a valve spring 164 interposed axially between the head 158 and a transverse annular rim 166 , oriented in a downstream direction, of the intermediate cavity 152 . The control collar 160 of the valve 148 is designed to cooperate by contact with the upstream transverse surface of a transverse annular rim 168 arranged at the downstream axial end of the piston 32 so that, at the end of travel of the piston 32 in the upstream direction, the annular rim 168 comes into axial abutment against the transverse surface 162 of the control collar 160 in order to cause an axial movement of the valve 148 in the upstream direction, counter to its spring 164 . The movement of the valve 148 in the upstream direction causes the opening of the discharge orifice 150 , which connects the downstream chamber 36 to the reservoir 29 at the end of the travel of the piston 32 in the upstream direction. The functioning of the assistance cylinder 30 according to the second embodiment is similar to that of the assistance cylinder 30 according to the first embodiment. Compared with the first embodiment, the discharge valve 148 according to the second embodiment has the advantage of requiring a shorter axial travel in order to cause the connection of the downstream chamber 36 to the reservoir 29 , with a sufficient cross section of flow of the fluid. FIG. 10 depicts schematically a third embodiment of the control system 10 according to the invention, in which the assistance device 50 comprises an electrical actuator 170 that controls the relaxation of an elastic assistance element 172 during the declutching phase. According to this embodiment, the assistance force F a is therefore produced by the relaxation of an elastic assistance element 172 , here a helical compression spring, as in the first and second embodiments. The cam mechanism 114 here has been replaced by the electrical actuator 170 . In the diagram in FIG. 10 , the electrical actuator 170 comprises a lever 174 which is interposed axially between the rod 48 of the assistance piston 32 and the movable axial end of the assistance spring 172 , and which is controlled pivotally by the transmission shaft 176 on the electric motor 178 . The assistance spring 172 stores elastic energy during the engagement phase, in particular under the effect of the elastic return of the clutch 12 towards its engagement position, which pushes the assistance piston 32 towards its upstream position. During the declutching phase, the electrical actuator 170 releases the assistance spring 172 so as to produce the assistance force F a on the piston 32 . The motor 178 is preferably controlled by an electronic control unit 180 which constitutes a means 115 of regulating the assistance force F a . The control unit 180 controls, for example, the electric motor 178 in accordance with operating parameters such as: the hydraulic pressure P h in the upstream circuit 40 , the travel C p of the clutch pedal 22 , data D ext external to the control system 10 , for example data relating to the functioning of the vehicle engine, the functioning of the vehicle gearbox, the functioning of the clutch 12 , etc. The operating parameters can be supplied to the control unit 180 by sensors (not shown). The value of the travel C p of the pedal 22 can be supplied to the control unit 189 by the electric motor 178 , in particular in the case where the rotation of its transmission shaft is linked to the sliding of the assistance piston 32 . The control unit 180 can modulate the assistance force F a according to at least one predetermined assistance law. A fourth and fifth embodiment of the control system 10 according to the invention are now described, in which the assistance device 50 is connected to an energy source 182 , 184 which is external to the control system 10 and which is installed in the vehicle that the control system 10 equips. According to these embodiments, the assistance force F a is produced by the external energy source 182 , 184 and is then transmitted to the assistance piston 32 . In the fourth embodiment, depicted in FIG. 11 , the external energy source 182 consists of a source of electric current, which may be the system supplying electrical energy to the vehicle. The assistance cylinder 30 of the fourth embodiment is roughly similar to that of the second embodiment, depicted in FIG. 9 , except that the cam mechanism 114 of the assistance device 50 is replaced by an electrical actuator 186 which acts directly on the transmission rod 71 . According to the embodiment depicted, the transmission rod 71 is equipped, at its upstream axial end, with a threaded portion 188 which is mounted screwed on a threaded shaft 190 able to be driven in rotation about its axis A 1 by an electric motor 192 , which is connected to the source of electric current 182 . Advantageously, the electric motor 154 can be controlled by an electronic control unit (not shown in FIG. 11 ) in the same way as the third embodiment described above ( FIG. 10 ). In the fifth embodiment, illustrated by FIGS. 12 to 19 , the external energy source 184 consists of a hydraulic or pneumatic pressure source. In the remainder of the description, non-limitingly, solely a hydraulic pressure source 184 will be considered, although a pneumatic pressure source can also be envisaged. FIG. 12 illustrates the operating principle of the fifth embodiment. In the fifth embodiment, the control rod 48 of the assistance piston 32 is linked in axial movement (A 1 ) to a ram 194 connected to the pressure source 184 by an auxiliary control circuit 185 , so as to transmit an assistance force F a to the assistance piston 32 during the declutching phase. The ram 194 comprises a so-called auxiliary piston 196 which slides in an auxiliary cylinder 198 and which, upstream, delimits an auxiliary control chamber 200 . The auxiliary piston 194 cooperates, for example, by contact with the control rod 48 of the assistance piston 32 . During the declutching phase, the pressure source 184 causes an increase in the hydraulic pressure P h in the control chamber 200 of the ram 194 , which produces an assistance force F a on the assistance piston 32 , by means of the control rod 48 , or transmission rod. FIG. 13 depicts an example of an assistance cylinder 30 equipped with a ram 194 in accordance with the teachings of the invention, and in which the auxiliary piston 196 is replaced by a flexible membrane 197 , or “unwinding” membrane. On the left-hand part of FIG. 13 , the assistance piston 32 is shown in the downstream position and on the right-hand part the assistance piston 32 is shown in the upstream position. The assistance piston 32 is here produced in a similar manner to that of the second embodiment ( FIG. 9 ), except that the discharge orifice 52 and the discharge valve 54 are produced in an axial orientation in the body of the assistance piston 32 , as on the variant described with reference to FIG. 4 . The discharge orifice 52 is offset with respect to the axis to allow a centred abutment of the rod 48 on the piston 32 . In the case of an inclined mounting of the assistance cylinder 30 , the orifice 52 is put in the high position in order to guarantee the purging of the air downstream of the piston 32 , at the time of mounting. The auxiliary cylinder 198 of the ram 194 is arranged here at the upstream axial end of the assistance cylinder 30 . The auxiliary cylinder 198 can be formed in an extension of the assistance cylinder body 56 . The membrane 197 is sealed in the auxiliary cylinder so as to delimit, on the same side as its upstream transverse face 202 , the control chamber 200 which is connected to the pressure source 184 by an auxiliary orifice 204 . The membrane 197 is here of the single-acting type since its downstream transverse face 206 is exposed to atmospheric pressure. The control rod 48 of the assistance piston 32 , or transmission road, comprises at its upstream axial end an abutment disc 208 which is in contact with the downstream transverse face 206 of the membrane 197 . When the hydraulic pressure P h increases in the control chamber 200 , exceeding atmospheric pressure, the membrane 197 “unwinds”, exerting an axial abutment force directed in the downstream direction on the disc 208 , which produces an assistance force F a on the piston 32 , by means of the transmission rod 48 . A variant of this latter embodiment, illustrated in FIG. 19 , consists of using the abutment between the rod 480 on the piston 320 in order to control the opening of a discharge orifice 520 . In this case, the orifice 520 is a channel pierced in the piston 320 along the axis of the rod 480 , and the end of this rod 480 has a complementary shape with respect to that of the outlet 540 of the orifice 420 so as to achieve the obstruction of this orifice when the rod is in abutment on the piston. An elastomer seal can be placed between the rod and the piston. When the clutch is engaged and the assistance is not activated, a small clearance is created between this rod 480 and the piston 320 , the orifice 520 is free. This orifice closes when the assistance force occurs. This variant is simple to implement since it does not require any supplementary part and keeps all the advantages of the discharge orifices presented above. FIGS. 14 to 18 illustrate several possible solutions for regulating the assistance force F a produced by the ram 194 . According to a first solution, illustrated by FIGS. 14 and 15 , the means 115 of regulating the assistance force F a consists of two control valves 210 , 212 which constitute respectively a charging valve 210 and a discharge valve 212 and which are connected by the auxiliary circuit 185 to the control chamber 200 of the ram 194 . In addition, the charging valve 210 is connected to the pressure source 184 and the discharge valve is connected to a fluid reservoir 29 . A charging valve 210 and a discharge valve 212 are controlled here by the hydraulic pressure P h in the upstream circuit 40 counter to the return force of a spring 214 , 216 associated with each valve 210 , 212 . Advantageously, the stiffness of the spring 214 associated with the charging valve 210 is greater than the stiffness of the spring 216 associated with the discharge valve 212 , so that the opening of the charging valve 210 and the closing of the discharge valve 212 are offset in time, during the declutching travel. In FIG. 14 , the control system 10 is depicted at rest, in the engaged position, which corresponds to an absence of pressure in the upstream hydraulic circuit 40 . In this position, the charging valve 210 is closed and the discharge valve 212 is open, so that the auxiliary circuit 185 is connected to the reservoir 29 . An explanation is now given of the functioning of the control system 10 of the FIG. 14 , during the declutching phase, considering in particular FIG. 15 . In FIG. 15 , the curve C aval1 in a continuous line represents the change in the hydraulic pressure P h in the downstream chamber 36 of the assistance cylinder 30 during the declutching phase, as a function of the travel C p of the clutch pedal 22 , when the clutch 12 is worn. The curve C aval2 , in a broken line, represents the same change as the curve C aval1 , when the clutch 12 is new. When the clutch 12 wears, the hydraulic pressure P h necessary for performing the declutching operation increases. The curve C amont in a continuous line represents the change in the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 , during the declutching phase, as a function of the travel C p of the clutch pedal 22 . When the clutch pedal 22 is actuated, the hydraulic pressure P h in the upstream circuit 40 increases. After a first travel C p1 of the pedal 22 , the hydraulic pressure P h reaches a first threshold value P hs which is sufficient to cause the movement of the discharge valve 212 counter to its spring 216 , which causes the closure F v212 of the discharge valve 212 . After a second travel C p2 of the pedal 22 , the hydraulic pressure P h reaches a second threshold value P hr , referred to as the regulated value, which is sufficient to cause the movement of the charging valve 210 counter to its spring 214 , which causes the first opening O v1 of the charging valve 210 . The charging valve 210 being open, the pressure source 184 is connected to the control chamber 200 of the ram 194 , which produces an assistance force F a on the piston 32 . The assistance force F a applied to the piston 32 causes a reduction in the hydraulic pressure P h in the upstream circuit 40 so that, after a given lapse of time, which corresponds to a third travel C p3 of the pedal 22 , the charging valve 210 returns to its idle position, which corresponds to a first closure F v1 of the charging valve 210 . It should be noted that the discharge valve 212 remains closed since the hydraulic pressure P h in the upstream circuit 40 does not drop as far as the threshold value P hs associated with this valve 212 . The return of the charging valve 210 to its idle position once again causes an increase in the hydraulic pressure P h in the upstream circuit 40 since, the pedal 22 continuing its pressing-down travel, there is a drop in pressure in the control chamber 200 due to the descent of the ram 196 . After a fourth travel C p4 of the pedal 22 , the hydraulic pressure P h once again reaches the regulated value, which causes a second opening O v2 of the charging valve 210 . This succession of openings and closings of the charging valve 210 continues until the assistance piston 32 is occupying its downstream position. In practice, in order to limit these oscillations, use is made of a charging valve 210 which opens and closes progressively for small oscillations from the regulated value P hr in this way, the openings and closings are not abrupt and the equilibrium position is reached more rapidly. The charging valve 210 therefore allows a closed-loop regulation of the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 , which stabilises around the regulated value P hr . Consequently, as the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 is linked to the pressure P h in the sending cylinder 14 , the force that the user must apply to the pedal 22 tends towards a constant value throughout the declutching phase. When the user releases the pedal 22 , the hydraulic pressure P h decreases in the upstream chamber 34 , which first of all causes the closure of the charging valve 210 and then, having arrived at the first threshold value P hs , the opening of the discharge valve 212 permitting the return of the assistance piston 32 to its upstream position. One advantage of this solution is that the force used by the user on the pedal 22 is not dependent on the wear on the clutch 12 . This advantage is illustrated in FIG. 15 by the fact that the pressure curve C amont is identical for the two pressure curves C ava11 , C ava12 associated with the downstream chamber 36 , the one corresponding to a worn clutch 12 and the one corresponding to a new clutch 12 . According to a second solution, which is illustrated by FIGS. 16 and 17 , the two valves 210 , 212 provided in the first solution are replaced by a single three-position control valve 218 . A first position of the control valve 218 , referred to as the charging position, causes the connection of the control chamber 200 to the pressure source 184 . A second position, or intermediate position, of the control valve 218 corresponds to a closure position of the control valve 218 . A third position of the control valve 218 , referred to as the discharge position, causes the connection of the control chamber 200 to the fluid reservoir 29 . In FIG. 16 , the control valve 218 is shown in its discharge position. The control valve 218 has two control pressures P c1 , P c2 which are applied on each side of the control valve 218 with identical abutment surfaces. The first control pressure P c1 corresponds to the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 , and is applied at the same side as the first position. The second control pressure P c2 corresponds to the hydraulic pressure P h in the control chamber 200 of the ram 194 and is applied at the third position. The functioning of the control valve 218 is as follows. When the two control pressures P c1 , P c2 , are equal, that is to say when the hydraulic pressure P h is equal in the upstream chamber 34 and in the control chamber 200 , the control valve 218 occupies its intermediate closure position. When the first control pressure P c1 is greater than the second control pressure P c2 , that is to say when the pressure in the upstream chamber 34 is greater than the pressure in the control chamber 200 , the control valve 218 occupies its charging position. When the first control pressure P c1 is less than the second control pressure P c2 , that is to say when the pressure in the upstream chamber 34 is less than the pressure in the control chamber 200 , the control valve 218 occupies its discharge position. The embodiment depicted in FIG. 16 thus makes it possible to effect a so-called proportional regulation of the assistance force F a , which is illustrated by FIG. 17 . The curve C aval in a continuous line represents the change in the hydraulic pressure P h in the downstream chamber 36 of the assistance cylinder 30 , during the declutching phase, as a function of the travel C p of the clutch pedal 22 . The curve C amont in a broken line represents the change in the hydraulic pressure P h in the upstream chamber 34 of the assistance cylinder 30 , during the declutching phase, as a function of the travel C p of the clutch pedal 22 . It is found that, in the particular case, illustrated here, where the abutment surfaces of the control pressures P c1 , P c2 are identical, the assistance force F a produces approximately one half of the total force to be supplied on the piston of the receiving cylinder 18 . Naturally, it is possible to modify the ratio between the assistance force F a and the total source to be supplied by modifying the ratio between the abutment surfaces of the control pressures P c1 , P c2 . FIG. 18 depicts a third solution in which the regulation means 115 is a three-position control valve 218 , as in FIG. 18 , but which is differentiated from the second solution in that the control valve 218 is controlled by an electronic control unit 220 . The control unit 220 can control the control valve 218 according to control parameters measured by sensors such as the travel of the pedal C p , the hydraulic pressure in the upstream chamber 34 and external data D ext . The control unit 220 can also control the pressure source 184 , which makes it possible to precisely apportion the required assistance force F a . According to the embodiment depicted in FIG. 18 , by virtue of the control unit 220 , it is possible to precisely choose the required assistance curve. In particular, it is possible to reproduce the assistance curve of the first and second solutions ( FIGS. 15 and 17 ). It should be noted that the embodiments of the control system 10 according to the invention, which are depicted with the discharge valve 54 produced axially in the assistance piston 32 and with a single connection to the fluid reservoir 29 , could have been represented with two connections of the reservoir 29 , as depicted and described in particular with reference to FIGS. 2 and 3 . According to a variant (not shown) of the various embodiments described above, it is possible to add in the fluid passage, either in the upstream 40 or downstream 44 circuit, or in the control circuit 185 of the assistance ram 196 , a device reducing the cross section of flow of the fluid in the direction of engagement. This device can be a valve that occupies a first position forming a maximum cross section of flow in the direction of disengagement, and a second position forming a reduced cross section of flow in the direction of engagement. Such a device makes it possible in particular to avoid an impact when releasing the pedal 22 too rapidly. More generally, the assistance device 5 can comprise a regulation means 218 which varies the value of the assistance force F a as a function of the upstream pressure P h in the upstream chamber 34 of the assistance cylinder 30 , or the downstream pressure P h in the downstream chamber 36 , or a combination of the two pressures, according to a predetermined assistance law.

The invention relates to a system for the hydraulic control ( 10 ) of a clutch ( 12 ), e.g. a motor vehicle clutch, comprising an upstream master cylinder ( 14 ) which is connected to a down-stream slave cylinder ( 18 ) by means of a conduit ( 16 ). The invention is characterized in that the system comprises a servo cylinder ( 30 ) which is disposed in the conduit ( 16 ) between the master cylinder ( 14 ) and the slave cylinder ( 18 ), said servo cylinder comprising at least one servo piston which can be subjected to an assist force produced by a servo device.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the hunting of wild game and, in particular, to a portable device for the hoisting and skinning of wild game in the field. 2. Description of the Related Art Hunters have hunted, killed and skinned wild game since before recorded history. The skinning and dressing of game in the field is best done when the game is hoisted off of the ground into a hanging position with either the head of the game elevated and the rear legs hanging down, or with the rear legs elevated and the head and the front legs hanging down. Game can be long and heavy, so it is necessary that the game be hoisted to a sufficient height to enable a person to manipulate the game as necessary to remove the skin without the game dragging on the ground. Numerous patents disclose vehicle mounted, tree depending and free standing game hoists. Game hoists are generally used in remote areas and have to be transported to the location of use. Portability is a key factor for game hoists to be used in the field. Tree depending game hoists utilize a tree for structural support, while free standing game hoists generally require a rigid support which may add to the weight of the device. Vehicle depending game hoists are generally similar to free standing devices but are adapted to be supported by a trailer hitch or other component of the motor vehicle. Several inventions are known to those skilled in the art for hoisting killed game into position for skinning. U.S. Pat. No. 5,562,534 (“the '534 patent”) discloses a game hoist having a dual-purpose winch. The '534 patent also discloses a first pulley used with the winch for hoisting game and a second pulley used with the winch for skinning game. After the game is hoisted to a hanging position, the game is secured in the hanging position and the winch is used, in combination with a second pulley, to pull the skin of the game. The '534 patent is a tree depending hoist and requires the user to find a tree having a trunk suitable for receiving straps or chains used to secure the winch, the first pulley and the second pulley. Tree depending game hoists generally require a tree having an uninterrupted section of trunk with no limbs and a diameter within a certain range. A problem with tree depending hoists like the one disclosed in the '534 patent is that a ladder may be required in order to secure the hoist to the tree at a height sufficient to prevent hoisted game from contacting the ground during skinning process. Another problem with tree depending game hoists like the one disclosed in the '534 patent is that the second pulley is secured to the trunk of a tree instead of being strategically positioned directly underneath the hoisted game. This may cause the game to be pulled in a direction other than straight down, and the game may swing or spin during or after the skinning process. Also, the game hoist disclosed in the '534 patent may not be usable if the tree does not have a extended portion of suitable diameter trunk near the ground that is without limbs or other naturally occurring features that may prevent the attachment and use of the lower pulley. Another problem with game hoists like the one disclosed in the '534 patent is the requirement of a second pulley. The user must unthread the strap or cable from the first pulley after hoisting the game, and then thread the strap or cable around the second pulley for skinning the game. This manipulation of the strap or cable may be time consuming and difficult, especially in cold weather when the manual dexterity of the user's hands is impaired by cold or by gloves. Also, the requirement of the second pulley adds unnecessary weight to the device. Another problem with game hoists like the one disclosed in the '534 patent is that it supports only a single game, and will not accommodate multiple game. Hunters that hunt in groups would each need to bring their own individual game hoist or they would have to skin one game at a time while other game lay on the ground attracting insects or scavengers. Another problem with game hoists like the one disclosed in the '534 patent is that it does not assist the user in loading skinned game into a truck or onto a motor vehicle unless the vehicle can be positioned under the tree to which the device is secured. What is needed is a game gallows for hoisting and skinning game that is more portable for easier transport to the field. What is needed is a game gallows that allows the user to hoist and skin the game without removing the strap or cable from a hoisting pulley and rethreading the strap or cable over a skinning pulley. What is needed is a game gallows for simultaneously hoisting and skinning multiple game. What is needed is a game gallows that is suitable for loading game into the bed of a truck or onto a motor vehicle. SUMMARY OF THE INVENTION The present invention provides a device for skinning game that overcomes the disadvantages in the prior art. The present invention provides a game gallows for skinning game that is suitable for being supported by a vehicle or for use as a free standing gallows. The present invention provides a game gallows that allows the simultaneous processing (dressing or skinning) of multiple game. The present invention provides a game gallows that does not require the user to remove and rethread straps or cables around different pulleys. The present invention includes a support and a rotatable hanger assembly. The hanger assembly is designed to accommodate a plurality of killed game and has a generally vertical axis of rotation. The support has a pulley arm pivotally coupled to the support for rotation in a generally vertical plane. In one embodiment, the first leg of the pulley arm is pivotally coupled to the support, and the second leg of the pulley arm extends generally perpendicular from the first leg and is coupled to a pulley. The first leg of the pulley arm also has a winch for pulling a strap or cable that passes around the pulley into tension. The pulley arm pivots between a superior position, with the second leg and the pulley secured into a position near the hanger assembly, and an inferior position, with the second leg and the pulley secured into a position near the ground. The winch operatively engages a strap or pulley that is threaded around the pulley for pulling in a generally vertical direction: upwardly when the second leg and pulley are secured into the superior position near the hanger assembly (for hoisting), and downwardly when the second leg and pulley are secured into the inferior position near the ground (for skinning). With the pulley arm in the superior position, the winch pulls the strap or cable to hoist game into a hanging position for hanging the game onto one of the hangers on the hanger assembly. With the pulley arm in the inferior position, the winch pulls the strap or cable to skin a game that is secured to and hanging on a hanger. BRIEF DESCRIPTION OF THE DRAWINGS So that the above recited features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. FIG. 1 is a perspective view of the game gallows of the present invention with the pulley arm in the hoisting position. FIG. 2 is a perspective view of the game gallows of the present invention with the pulley arm in the skinning position. FIG. 3 is a perspective view of the game gallows of the present invention with the pulley arm rotating from the hoisting position to the skinning position. FIG. 4 is an elevational view of the dismembered killed game being hoisted to a hanging position using the game gallows of the present invention. FIG. 5 is an elevational view of a second dismembered game being coupled to an open hanger after the first dismembered game awaits skinning. FIG. 6 is an elevational view of the game gallows of the present invention with the pulley arm in the skinning position and the strap coupled to the skin of a game. FIG. 7 is an elevational view of the game gallows of the present invention with the winch being used to skin a game. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a perspective view of one embodiment of the game gallows of the present invention. The embodiment of the game gallows 10 depicted in FIG. 1 comprises a support 12 having a first end 14 and a second end 16 , a rotatable hanger assembly 20 that is rotatably coupled to the first end 14 of the support 12 . The hanger assembly 20 has a plurality of radially outwardly extending hangers 22 , each of which can support a game. Each hanger 22 has a chain plate 23 coupled along the top of the hanger 22 , and each chain plate 23 has a link channel 25 of a width slightly greater than the diameter of the links of the chain 24 that is secured to the chain plate 23 . The chain 24 can be secured to a game (not shown) by inserting a link of the chain 24 into the link channel 25 of the chain plate 23 as shown on FIG. 1 . In the embodiment shown in FIG. 1 , a base 40 is coupled to the second end 16 of the support 12 . FIG. 1 shows a base 40 having a plurality of radially outwardly extending legs 42 that generally lie in a horizontal plane. Preferably, the legs 42 may have a one to three degree downwardly slope from center to end to provide additional stability when placed upon soft ground. The embodiment of the game gallows 10 is depicted in FIG. 1 further comprises radially outwardly telescoping leg extenders 43 . Deployment of the leg extenders 43 , as shown in FIG. 1 , improves stability of the game gallows 10 . The embodiment of the game gallows 10 depicted in FIG. 1 further comprises a pulley arm 50 having a first leg 52 and a second leg 54 , the first leg 52 being pivotally coupled to the support 12 at a pivot 60 . The first leg 52 of the pulley arm 50 is also coupled to a winch 62 having a strap 64 rolled onto a spool. The second leg 54 of the pulley arm 50 extends generally perpendicular to the first leg 52 and is coupled to a pulley 56 around which the strap 64 is threaded. “Strap,” as that term is used herein, refers to a strap, wire, rope, cable or any other elongated flexible tether suitable for use with a winch. The winch 62 may be any suitable means of reeling in and storing, unreeling and feeding out, and locking strap. Alternately, a winch having a gear sprocket can utilize a chain. A Fulton Performance Products, Inc. (of Mosinee, Wis.) Trailer Winch model T903, 900 pound capacity is preferred. The pulley 56 shown in FIG. 1 comprises a tubular hollow shaft rotatable on an axle received into its hollow interior. The support 12 may have a plurality of foot pegs 70 welded onto the support 12 and generally perpendicular to the support 12 . The pegs 70 are located between the pivot 60 and the second end 16 of the support 12 . The foot pegs 70 enable the user to climb the support 12 to reach the hangers 22 of the hanger assembly 20 or the chains 24 hanging on the hangers 22 . The game gallows 10 further comprises retainer 80 for engaging the pulley arm 50 and securing the pulley arm in the hoisting position. The game gallows 10 further comprises a lower retainer 81 for engaging the pulley arm 50 and for securing the pulley arm 50 in the skinning position. The upper retainer 80 allows the pulley arm 50 to be secured in the hoisting position ( FIG. 1 ), and the lower retainer 81 allows the pulley arm 50 to be secured in the skinning position ( FIG. 2 ). As shown in FIGS. 1 and 2 , each hanger 22 may include a chain 24 . A hanging tool, such as a collar or a gambrel (not shown), is fitted or secured around the head or coupled to the rear legs of a game (not shown), respectively, and is used to couple the game to the hook 26 on the strap 64 to hoist the game into position using the winch 62 . FIG. 3 is a perspective view of the game gallows 10 of the present invention with the pulley arm 50 rotating from the hoisting position (shown in FIG. 1 ) to the skinning position shown in FIG. 2 . The pulley arm 50 is shown in FIG. 3 to be rotating about the pivot 60 away from the upper retainer 80 in a clockwise direction, and will continue to rotate until it reaches the skinning position shown in FIG. 2 and is received into and secured by the lower retainer 81 (shown in FIG. 2 ). FIG. 4 is an elevational view of a first dismembered game 92 being hoisted to a hanging position using the game gallows 10 of the present invention. The game 92 is secured to the strap 64 by the hook 26 that is coupled to the end of the strap 64 . The hook 26 engages the collar 91 that is secured around the neck of the game 92 , and the winch 62 is operated to reel in and pull tension in the strap 64 that is threaded over the pulley 56 . FIG. 5 is an elevational view of the first dismembered game 92 being coupled to the hanger assembly 20 of the game gallows 10 for skinning. The first dismembered game 92 is lifted high enough to allow the user to pull the chain 24 through the collar 91 and to insert a link of the chain 24 into the link channel 25 of the chain plate 23 as shown in FIG. 5 . Once the weight of the first dismembered game 92 is supported by the chain 24 , the hanger 22 and the hanger assembly 20 , the hook 26 and the strap 64 can be disengaged from the collar 91 . The hanger assembly 20 can then rotate to remove the killed game 92 from the lift zone. FIG. 6 is an elevational view of one embodiment of the game gallows 10 of the present invention with a second dismembered game 93 secured to the hanger assembly 20 and the pulley arm 50 rotated to the skinning position. The first dismembered game 92 is shown to have been moved to the right by rotation of the hanger assembly 20 . The strap 64 and hook 26 are coupled to the skin of the second dismembered game 93 using a collar 91 . The hook 26 and the strap 64 are secured to a flap 95 of the skin of the second dismembered game 93 using a skinning tool 94 . The operation of the winch 62 reels in and produces tension in the strap 64 enabling the user to forcibly pull the flap 95 and skin the second dismembered game 93 . FIG. 7 is an elevational view of one embodiment of the game gallows 10 of the present invention with the winch 62 being used to skin the second dismembered game 93 . The flap 95 of the second dismembered game 93 grows larger as the winch 62 is turned to pull the strap 64 and skin the second dismembered game 93 . It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. For example, the game gallows is shown in the drawings as free standing, but is easily adapted for being tree-depending or vehicle depending. For tree depending, the support 12 may be secured to a tree or post using straps, bands or clamps, or any of the other devices used to secure items to trees or posts that are known in the prior art. The device disclosed above and shown in FIGS. 1–7 can be adapted to make a tree depending game hoist by providing an offset between the axis of the rotating hanger assembly 20 and the support 12 . For vehicle depending, the radially outwardly extending leg 42 (see FIG. 1 ) that is opposite the pulley arm 50 may be inserted into a receptacle, such as a standard 1½ inch square or 2 inch square standard trailer hitch. This enables the user to winch a game, couple the game to a hanger 22 , and rotate the hanger assembly 20 to position the game over the bed of a truck or other cargo surface of a vehicle, then use to winch 62 to lower the game onto the truck bed or cargo surface. This description is intended for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. “A,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.

The present invention discloses portable game gallows for hoisting and skinning multiple game. The portable game gallows includes a winch having a strap or cable that can be used to raise game into position for hanging on a rotating tree and for skinning game that is hung from the tree. The present invention discloses a dual purpose pulley that can be locked into a first position for hoisting a game or a second position for skinning a game.

BACKGROUND OF THE INVENTION The present invention relates generally to the art of magnetic resonance. It finds particular application to magnetic resonance imaging receiver coil systems having detachable, relocatable, and/or interchangeable sections. It will be appreciated, however, that the present invention is also applicable to the examination of other portions of the human anatomy and to the imaging or spectroscopic examination of non-human subjects or other objects, materials, and so forth. Conventionally, magnetic resonance imaging systems generate a strong, uniform, static magnetic field in a free space between poles or in a bore of a magnet. This main magnetic field polarizes the nuclear spin system of an object to be imaged placed therein. The polarized object then possesses a macroscopic magnetic moment vector pointing in the direction of the main magnetic field. In a superconducting main annular or bore magnet assembly, the static magnetic field B 0 is generated along a longitudinal or z-axis of the cylindrical bore. To generate a magnetic resonance signal, the polarized spin system is excited by applying a magnetic resonance signal or radio frequency field B 1 perpendicular to the z-axis. The frequency of the magnetic resonance signal is proportional to the gyromagnetic ratio γ of the dipole(s) of interest. The radio frequency coil is commonly tuned to the magnetic resonance frequency of the selected dipole of interest, e.g., 64 MHZ for hydrogen dipoles 1 H in a 1.5 Tesla magnetic field. Typically, a radio frequency coil for generating the magnetic resonance signal is mounted inside the bore surrounding the sample or patient/subject to be imaged. In a transmission mode, the radio frequency coil is pulsed to tip the magnetization of the polarized sample away from the z-axis. As the magnetization precesses around the z-axis back toward alignment, the precessing magnetic moment generates a magnetic resonance signal which is received by the radio frequency coil in a reception mode. For imaging, a magnetic field gradient coil is pulsed for spatially encoding the magnetization of the sample. Typically, the gradient magnetic field pulses include gradient pulses pointing in the z-direction but changing in magnitude linearly in the x, y, and z-directions, generally denoted G x , G y , and G z , respectively. The gradient magnetic fields are typically produced by a gradient coil which is located inside the bore of the magnet and outside of the radio frequency coil. Conventionally, when imaging the torso, a whole body radio frequency coil is used in both transmit and receive modes. By distinction, when imaging the head, neck, shoulders, or an extremity, the whole body coil is often used in the transmission mode to generate the uniform excitation field B 1 and a local coil is used in the receive mode. Placing the local coil surrounding or close to the imaged region improves the signal-to-noise ratio and the resolution. In some procedures, local coils are used for both transmission and reception. One drawback to local coils it that they tend to be relatively small and claustrophobic. One type of local frequency coil is known as the “birdcage” coil. See, for example, U.S. Pat. No. 4,692,705 to Hayes. Typically, a birdcage coil is cylindrical and comprises a pair of circular end rings which are bridged by a plurality of equi-spaced straight segments or legs. Birdcage head coils are capable of providing a high signal-to-noise ratio (SNR) and achieving readily homogeneous images. Birdcage coils are widely used for functional MRI (fMRI) and other applications. Birdcage coils, however, are not without their disadvantages. Since, generally, the SNR and thus image quality increases with decreasing distance between the receiver coil and the volume being imaged, birdcage coils are generally designed so that they will be located very close to the subject's head, particularly since fMRI applications require the ability to extract small signals (e.g., reported to be as low as about 2-5% at 1.5 T). As the name implies, birdcage coils are also closed or cage-like in nature and thus restrict access to the subject's face and head. This results in a lack of space for placement of stimulation devices that would be desirable for fMRI experiments. Stimulation devices are devices constructed to stimulate a specific neural function of a subject, the response to which is sought to be observed through imaging the appropriate region of the brain. Such stimulators may emit, for example, mechanical, electrical, thermal, sound, or light signals designed to stimulate the neural activity of interest. The neural activity is induced by sensory stimuli, such as visual, auditory, or olfactory stimuli, taste, tactile discrimination, pain and temperature stimuli, proprioceptive stimuli, and so forth. Since the birdcage design is close fitting and not particularly open in nature, many such stimulation experiments must be performed in a manner that is suboptimal, if at all. For example, the use of a birdcage coil might preclude, due to space constraints, the use of an auditory stimulation device, such as a headphone set. Likewise, since bars are placed over the face, and in some instances directly over the eyes, birdcage coils are particularly disadvantageous for eye-tracking experiments or other visualization experiments. Another problem with birdcage coils is that the design limits access to the patient, e.g., for therapeutic, physiological monitoring, and patient comfort purposes. Access may be needed, for example, to monitor physiological functions, such as oxygen levels, or to perform interventional medicine or use life-support devices, such as ventilator tubes, tracheotomy tubes, etc., while imaging a patient. Drug delivery, contrast agent delivery, and delivery of gases such as anesthetizing gases, contrast-enhancing gases, and the like, also require patient access. Also, it is also often desirable to enhance patient comfort through the use of patient comfort devices. However, the proximity of the axial segments to one another and to the head of the patient impairs such practices. Yet another problem with birdcage head coils is their claustrophobic effect on patients. Many pediatric and adult patients already experience claustrophobic reactions when placed inside the horizontal bore of a superconducting magnet. Placement of a close-fitting head coil having anterior legs which obstruct the direct view of the patients further adds to their discomfort. Attempts to reduce the discomfort have been made, for example, through the use of illumination inside the magnet bore, air flow, and the use of reflective mirrors. Although claustrophobic reactions and discomfort are sometimes reduced somewhat by such measures, claustrophobia can still be problematic. Birdcage coils are circularly polarized. Removing or altering the spacing of the legs adjacent the face alters the symmetry and can degrade performance. Other types of localized coils include a phased array of smaller surface coils. In this manner, a greater SNR (that increases in proportion to the number of elements) than birdcage design can be achieved. For fMRI applications, flexible coil arrays can be wrapped around the head. However, these so-called flex-wrap designs are lacking in the spatial openness necessary for stimulation studies, interventional imaging, and the accommodation of therapy devices. Furthermore, it is difficult to achieve uniform placement of coils, both as between different subjects and for repeat studies of the same subject. The present invention provides a new and improved localized RF coil that overcomes the above-referenced problems and others. SUMMARY OF THE INVENTION In one aspect, the present invention provides an radio frequency (RF) coil system for magnetic resonance imaging of one or more regions of a subject. The coil system includes a first coil section comprising one or more conductive coils in a first nonconductive housing, and a second coil section comprising one or more conductive coils in a second nonconductive housing, wherein the first and second coil sections are configured to be inherently decoupled or have minimal coupling. The coil system further comprises one or more fasteners removably and movably joining the housings of the first and second coil sections. In a further aspect, the present invention provides a magnetic resonance imaging system comprising a main field magnet for generating a temporally constant magnetic field along a main field axis and an RF coil system. The RF coil system includes a first coil section configured for maximum or predominant field sensitivity along a first axis perpendicular to the main magnetic field axis, a second coil section configured for maximum sensitivity along a second axis perpendicular to the first and main magnetic field axes, and a fastening system for selectively fastening the first and second coil sections on opposite sides of a region of interest for quadrature reception of resonance signals emanating from the region of interest. In yet a further aspect, the present invention provides a magnetic resonance method comprising the steps of establishing a polarizing magnetic field in a region of interest; exciting resonance of selected dipoles in the region of interest to generate magnetic resonance signals; and concurrently receiving the magnetic resonance on one side of the region of interest with a first linear coil having a maximum sensitivity along a first axis orthogonal to the polarizing magnetic field, and on an opposite side of the region of interest with a second linear coil having a maximum sensitivity along a second axis orthogonal to both the polarizing magnetic field and the first axis. One advantage of the present invention is that it increases spatial openness around the subject. Another advantage resides in its ability to easily select the desired coverage. Another advantage resides in improved accommodation for stimulation devices, such as the type used for fMRI experiments, and coil placement or removal options to maximize patient comfort. Another advantage resides in improved accommodation of patient comfort devices. Another advantage of the present invention is that detaching coil sections still permit the remaining coil sections to be operational. Another advantage of the present invention is that it accommodates life support or therapeutic devices such as ventilator tubing, tracheotomy tubes, immobilization collars, etc. Another advantage of the present invention is that it provides detachable and/or relocatable coil sections matched to fMRI experiments, such as auditory or visual fMRI experiments. In addition to providing openness in the space around the subject's head that matches the requirements of the particular fMRI procedure, data acquisition throughput is increased in that the region of interest can be tailored to the appropriate region of the brain, i.e., the region or regions containing the neural activity of interest. Another advantage of the present invention is that aliasing can be reduced by reduction of coverage of the excitation area. Yet another advantage of the present invention is that coil concentration can be increased for areas of interest or extended to areas not well covered by the current coil designs. Another advantage is that switching between different fMRI experiments and/or different stimulation equipment, such as between vision and auditory experiments, can be more readily performed. Still another advantage resides in its ability to monitor relatively small signals, such as in blood oxygen level dependent contrast (BOLD) studies. Yet another advantage of the present invention is that it allows a technologist to readily position and lock non-imaging devices. Still another advantage of the present invention is that it is readily adaptable to time-saving techniques where temporal resolution is desired. Still another advantage of the present invention is its adaptability to subjects having different body shapes and sizes, including subjects for whom the conventional head coil designs might provide an ill fit. Yet another advantage of the present invention is that it is can also be used for interventional imaging. Another advantage is that it allows addition, removal, and exchanging of coils. Other advantages include the improved physiological monitoring, improved drug and contrast agent delivery, and improved delivery of gases such as anesthetizing gases or contrast-enhancing, e.g., hyperpolarized, gases. Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. FIG. 1 is a diagrammatic illustration of a magnetic resonance imaging system apparatus including a coil construction in accordance with the present invention; FIGS. 2 and 3 are functional block diagram illustrating alternative embodiments of data acquisition circuitry for use with the RF coil system in accordance with the present invention; FIG. 4 illustrates a first exemplary embodiment of a coil construction according to the present invention; FIG. 5 shows the coil conductors of the embodiment of FIG. 4; FIG. 6 illustrates a manner in which the movable coil section of FIG. 5 can be relocated; FIG. 7 illustrates a second exemplary embodiment of a coil construction according to the present invention; FIG. 8 shows the coil conductors of the embodiment of FIG. 7; FIG. 9 illustrates an exemplary manner in which the movable coil section of FIG. 7 can be relocated; and FIG. 10 illustrates a coil system in accordance with the present invention comprising multiple interchangeable coil sections. FIG. 11 illustrates an alternative embodiment of a coil section of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, a plurality of primary magnetic coils 10 generate a uniform, temporally constant magnetic field B 0 along a longitudinal or z-axis of a central bore 12 . In a preferred superconducting embodiment, the primary magnet coils are supported by a former 14 and received in a toroidal helium vessel or can 16 . The vessel is filled with helium to maintain the primary magnet coils at superconducting temperatures. The can 16 is surrounded by a series of cold shields 18 which are supported in a vacuum dewar 20 . Of course, annular resistive magnets, open magnets, and the like are also contemplated. A whole body gradient coil assembly 30 includes x-, y-, and z-gradient coils mounted along the bore 12 for generating gradient magnetic fields, G x , G y , and G z along the x, y, and z axes, respectively. Preferably, the gradient coil assembly is a self-shielded gradient coil that includes primary x, y, and z-coil assemblies 32 plotted in a dielectric former and secondary x, y, and z-coil assemblies 34 that are supported on a bore defining cylinder of the vacuum dewar 20 . A whole body radio frequency coil 36 is mounted inside the gradient coil assembly 30 . A whole body radio frequency shield 38 , e.g., copper mesh, is mounted between the whole body RF coil 36 and the gradient coil assembly 30 . An insertable radio frequency head coil system 40 is removably inserted into the bore of an examination region defined about an isocenter of the magnet 10 . In the illustrated embodiment, the insertable radio frequency coil system 40 comprises front or face coil section 42 and rear or back coil section 44 . The front coil section 42 and the rear coil section 44 are shown aligned in opposing, facing relation defining a volume sized to receive a subject's head. The front coil is configured for maximum sensitivity to radio frequency signals along a first axis perpendicular to the main field or z-axis, e.g., the vertical axis. The rear coil is configured for maximum sensitivity to signals along an axis perpendicular to the first axis and the main field axis, e.g., the horizontal axis. In this manner, the front and rear coils are magnetically isolated and achieve quadrature detection. An operator interface and control station 50 includes a human-readable display 52 , such as a video, CRT, CCD, LCD, active matrix monitor, or the like, and one or more operator input devices including a keyboard 54 , a mouse 56 or other pointing device, such as a trackball, track pad, joystick, light pen, touch-screen overlay, and the like. A computer control and reconstruction module 58 includes hardware and software for enabling the operator to select among a plurality of preprogrammed magnetic resonance sequences that are stored in a sequence control memory of a sequence controller 60 . The sequence controller 60 controls gradient amplifiers 62 connected with the gradient coil assembly 30 for causing the generation of the G x , G y , and G z gradient magnetic fields at appropriate times during the selected gradient sequence. A digital transmitter 64 causes a selected one of the whole body and insertable radio frequency coils to generate B 1 radio frequency field pulses at times appropriate to the selected sequence. In certain embodiments, the coil construction 40 is employed as both a transmitter and receiver coil. The use of coil construction 40 for transmission and receiving is particularly advantageous for imaging methods which employ pre-excitation or presaturation pulses prior to the imaging portion of the pulse sequence, such as flow tagging angiographic methods, fat saturation methods, and the like. Resonance signals received by the coil construction 40 are demodulated by a data acquisition circuitry 66 and stored in a data memory 68 . A reconstruction or array processor 70 performs a two- or three-dimensional inverse Fourier transform, or other known transform, to reconstruct a volumetric image representation that is stored in an image memory 72 . A video processor 74 under operator control converts selected portions of the volumetric image representation into slice images, projection images, perspective views, or the like as is conventional in the art for display on the video monitor 52 . Referring now to FIG. 2, in a preferred embodiment of the data acquisition electronics 66 , the signal from each of n individual RF coils in the head coil system 40 is amplified by a corresponding one of n individual preamplifiers 80 a , 80 b , . . . , 80 n , where n is the number of receiver coils in head coil system 40 . The individual amplified signals are demodulated by n individual receivers 82 a , 82 b , . . . , 82 n and fed to an array of A/D converters including n individual A/D converters 84 a , 84 b , . . . , 84 n . A digital combiner 90 processes, weights, and combines the individual digital signals using standard digital signal processing techniques. The operator can also control the combiner 90 to divide the signals to be reconstructed to a plurality of related images. Alternatively, the signals from the coils can be digitized and then demodulated with digital receivers. The number of receiving channels depends on the particular MRI system and thus, it will be recognized that it is not necessary that the number of receiver channels be equal to the number of RF coils. For example, the signals from a plurality of coils may be multiplexed or otherwise combined in analog or digital fashion with appropriate combining circuitry as necessary in light of the number of receiver channels available on the imaging system employed. Referring now to FIG. 3, there appears a block diagram illustrating an alternative embodiment of data acquisition circuitry 66 . The 90° out of phase analog signals received by the front and rear RF coils of head coil system 40 are combined by a conventional quadrature coil combiner 80 , which typically phase shifts and adds the received signals. The resulting combined signal is supplied to a receiver 82 . Receiver 82 demodulates the combined signal and an analog-to-digital converter 84 digitizes the signal to numerical data representative of the magnetic resonance signals. The data thus produced is stored in the data memory 68 . Referring now to FIG. 4, there is shown a first exemplary embodiment of the head coil construction 40 according to the present invention. The front coil section 42 and the rear coil section 44 are constructed such that when arranged in facing relation, as depicted, they are inherently decoupled. As used herein, the terms “inherently decoupled” and “intrinsically isolated” describe coils or coil arrays that exhibit little or no mutual inductance. While complete decoupling is desirable, it will be recognized that complete decoupling is often a condition that cannot be met. Therefore, the terms “inherently decoupled” and “intrinsically isolated” are not intended to preclude small amounts of coupling that are acceptable to the operation of the coils. In the preferred embodiment, the decoupling is achieved by designing the front and rear coils to be linearly polarized along orthogonal axes, although other decoupling techniques are also contemplated. The inherent decoupling enables the front coil section 42 to be freely moved with respect to the rear coil section 44 , or to be removed altogether, without the need to retune either coil system. Also, the front coil section 42 is exchangeable with alternate coil systems having field sensitivity in the same direction, for example, having different sizes, coil configurations, and so forth, without the need to retune the rear coil system 44 . The front coil section 42 of head coil construction 40 comprises a housing 100 constructed of a nonconductive material enclosing conductive RF coils and one or more fasteners or fastening systems 104 . The fasteners 104 are depicted as elongate in the z-direction allowing front coil 42 to be removed and/or removably replaced at a plurality of, and preferably any number of, positions along the z-axis. The manner in which the front coil 42 can be freely positioned with respect to rear coil 44 is illustrated more clearly in FIG. 6 . Fasteners 104 are preferably hook and loop fasteners, such as Velcro® or similar material. Other fastener types include, but are not limited to, removably attachable adhesive material, one or more clamps or latches, straps, snap fit fasteners, fasteners forming a sliding engagement between the coil halves, such as a guide pin, guide roller, guide rib, and so forth engaging a complimentary groove. A means for reproducing a given set up can optionally be provided, such as a scale or other markings or indicia on the housings 100 and 102 . Where a sliding engagement between the coil halves is employed, they can optionally be positionable in a plurality of predetermined positions, for example, by providing one or more resilient or spring biased protrusions engaging a series of complimentary openings or depressions on the fastener 104 or housing halves 100 or 104 . In still further embodiments, handles can be provided on the detachable/relocatable coil section housings to facilitate coil section movement, removal, and replacement. The coils of the head coil construction 40 are illustrated in FIG. 5 . In the embodiment shown, the front coil section 42 comprises a pair of overlapping saddle or loop coils 106 and 108 , which are overlapped and positioned for minimum mutual inductance to form a phased array. Other coils which have maximum sensitivity in the vertical direction are also contemplated. The rear coil section 44 comprises a pair of overlapping butterfly coils 114 and 116 arranged in a phased array. Other coils with maximum sensitivity in the horizontal direction, such as double-D coils, are also contemplated. The coils are built with a conductive material, including but not limited to copper, aluminum, silver, or other conductive material. The coils can be built, for example, by laminating a nonconductive substrate with copper or other conductive foil, depositing a layer of copper or other metal onto a nonconductive substrate, and so forth. The coils can include conventional RF coil circuit components such as capacitors and so forth as appropriate to tune or match the coils as is known to those skilled in the art. Referring now to FIGS. 7 and 8, there is shown a head coil construction 40 ′ according to a second exemplary embodiment of the present invention. The head coil 40 ′ comprises a front coil section 42 ′ and a rear coil section 44 arranged in facing relation. Again, coil configurations which are inherently decoupled have been selected. The front coil section 42 ′ in this embodiment is freely moveable and removable with respect to rear coil section 44 without the need to retune either coil system. Also, the front coil section 42 ′ is exchangeable with alternate coil systems having field sensitivity in the same direction, for example, having different sizes, coil configurations, and so forth, without the need to retune the rear coil system 44 . A head coil system that comprises a plurality of differently configured front coil sections 42 and 42 ′, and the manner of their interchangeability, is illustrated in FIG. 10 . Referring again to FIGS. 7 and 8, front coil section 42 ′ of the head coil construction 40 ′ comprises a housing 100 ′ constructed of a nonconductive material enclosing a conductive RF coil 106 ′ and one or more fasteners 104 , as detailed above by way of reference to FIG. 4 . Again, fasteners 104 allow removal of the front coil 42 ′ and/or removable placement of front coil 42 ′ in a plurality of positions along the z-direction in a manner analogous to that shown in FIG. 6 . Likewise, coil system 42 ′ can also be rotated, e.g., 180 degrees, as illustrated in FIG. 9 . This facilitates placing the front coil close to the region of interest (ROI) to optimize sensitivity to signals from that region, but displaced from sources of artifacts such as moving eyes, metal dental work, and the like. Further, the fasteners can be used to attach other equipment in addition to or instead of the front coil section 42 ′. The coils of the head coil construction 40 ′, illustrated in the embodiment of FIG. 8, include a front coil section 42 ′ comprising a single loop saddle coil 106 ′ and the rear coil section 44 ′, comprising a pair of overlapping butterfly coils 114 and 116 arranged in a phased array. The coils are built with a conductive material and can include additional circuit components as described above by way of reference to FIG. 5 . The use of horizontal field coils in the rear coil is particularly advantageous when imaging the base of the brain, which is in close proximity to the rear coil. When other areas are of primary interest, the front coil can be the horizontal field coil and the rear coil can be the vertical field coil. In preferred embodiments, in addition to being physically displaceable, removable, and/or interchangeable, it is particularly advantageous that the front and rear coil systems of the present invention are electronically individually and selectively removable from the circuit. Likewise, it is particularly advantageous, when either or both of front and rear coil sections are multi-coil systems, that individual coils thereof be electronically individually and selectively removable or replaceable. In certain embodiments, the rear coil 44 includes a coil or a phased array of coils having a maximum sensitivity in a horizontal direction and a coil or phased array of coils having a maximum or predominant sensitivity in the vertical direction. An exemplary embodiment of such a rear coil arrangement is illustrated in FIG. 11, which includes overlapping butterfly coils 114 and 116 , and which further includes overlapping loop coils 120 and 122 . In operation, when a front coil (e.g., 42 , 42 ′)is present, the loop coils 120 and 122 are electronically removed from the circuit. However, when the front coil is removed in accordance with this teaching, coils 120 and 122 can be engaged and the rear coil alone can be used alone to provide quadrature detection. This configuration is advantageous for imaging the cervical spine and the back of the head, and for fMRI applications requiring access to the subject's face. The use of the rear coil section illustrated in FIG. 11 alone in a non-quadrature mode is also contemplated, e.g., wherein a front coil section is removed and wherein coils 120 and 122 are electronically removed. In operation, the RF coil construction in accordance with this teaching allows the MRI operator to perform anatomical imaging of the entire head followed by facile change in coil configuration, e.g., coil or coil set removal (either physical or electronic), adjustment of the front coil or coil set placement, exchange of coil sections for stimulation devices, comfort devices, or alternate coil sets. Calibration, landmark adjustment of the coil, and repeatable position of stimulation devices can also be improved through positioning. In certain embodiments, the entire coil system of the present invention is used for anatomical imaging of the entire head or the head and neck of the subject. The ability to slide or relocate the coil sections improve the adaptability in the coverage, accommodating a wide range of patient profiles, such as patient size, length of neck, kyphotic subjects, and other body types. The coil system in accordance with this teaching can also be used with any other coils or coils sets with which it is decoupled. For example, a head coil system in accordance with this teaching can be operated with a spinal imaging array for imaging the central nervous system. Other coils that can be used with the coil system of the present invention include thyroid coils, cardiac coils, or other local coils, such as a coil for imaging trauma sites, and so forth. Functional images may require only a portion of the region of interest to be acquired. Thus, during fMRI studies, one or more coils are moved or removed (either physically or electronically) to more closely tailor the imaging field of view (FOV) to match the region of interest during fMRI (e.g., the region appropriate to the brain response sought to be observed). This improves imaging throughput and accuracy while also improving access for placement of stimulation devices for use in fMRI experiments. In especially preferred embodiments, stimulation devices or patient comfort devices are connected, e.g., using fasteners 104 , or otherwise, or placed into positions vacated by the detached coil sections. Comfort devices are helpful in achieving patient cooperation, e.g., in the patient cooperating to remaining still. Comfort devices which may be employed with the present invention include, for example, audio and/or visual devices for the presentation of music, movies, television, and so forth. Advantageously, the comfort devices are exchangeable with removable coil section, for example, occupying a space vacated by the removal of a coil section. Coil sections integrating such comfort devices are also contemplated. In certain embodiments, a visual stimulation fMRI experiment is performed using the coil system in accordance with the present invention. The front coil section is moved to a position that does not obstruct the subject's field of vision (and optionally electronically removed) or physically removed. In a preferred aspect, the imaged region comprises the occipital lobe and cerebellum regions of the subject, and the imaged region does not include the subject's eye region. The coil construction of the present invention can also be modified to integrate stimulation devices, e.g., on or within the coil housing. For example, a combined stimulation device/RF coil section can include, for example, an auditory stimulation device such as audio speakers (e.g., in a headphone-like configuration within the coil section), optical displays, and the like. It will be recognized that the present invention is not limited to the above-described embodiments and that the invention is also applicable to other coil types. For example, the front coil loops are not limited to the configurations shown, and can comprise planar and non-planar loops (circular, square, rectangular, elliptical) and phased arrays thereof, Helmholtz coils, and the like. Likewise, the rear coil section can comprise a single butterfly coil or a phased array of more than two butterfly coils, ladder coils, double-D coils, and the like. For optimal signal-to-noise ratio, the front and rear coil systems have a quadrature relationship. Likewise, although the invention has been shown and described herein primarily by way of reference to a moveable, detachable, and/or interchangeable front coil section that is particularly suited for fMRI experiments requiring access to the facial region, other arrangements are contemplated as well. For example, the present invention can be readily adapted so as to provide access to the subject's ears, for example, through the use of removable coils or through the use of a coil configuration and housing having openings or cutaway regions allowing access to the ears. The description above should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. In light of the above description and examples, various other modifications and variations will now become apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents.

An RF coil construction ( 40, 40′ ) includes removable, relocatable, and/or detachable sections ( 42, 44 ) that are inherently decoupled. The sections can be relocated, removed, or exchanged with sections having different coil sizes or coil configurations, allowing the coil configuration to be tailored to a desired imaging procedure and region of the brain. The coil construction provides space for stimulation devices and adjusting patient access and comfort. Since the operator can select coil removal or placement to reduce the amount of data outside the region of interest, the coil construction can also reduce scanning and reconstruction time, reduce artifacts, and provide increased temporal resolution and image throughput.

CROSS-REFERENCES TO RELATED APPLICATIONS The present application is a continuation of U.S. patent application Ser. No. 10/975,555 filed Oct. 27, 2004 (now U.S. Pat. No. 7,811,296), which is a continuation in part of U.S. patent application Ser. No. 10/803,444 filed Mar. 17, 2004 (now U.S. Pat. No. 7,563,273), which is a continuation of U.S. patent application Ser. No. 09/894,463 filed Jun. 27, 2001 (now U.S. Pat. No. 6,752,813), which is a continuation in part of U.S. patent application Ser. No. 09/544,930 filed Apr. 7, 2000 (now U.S. Pat. No. 6,629,534), and which is a non-provisional of, and claims the benefit of U.S. Provisional Patent Application No. 60,128,690, filed Apr. 9, 1999. The entire contents of each of the above listed patent applications is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to medical methods, devices, and systems. In particular, the present invention relates to methods, devices, and systems for the endovascular, percutaneous or minimally invasive surgical treatment of bodily tissues, such as tissue approximation or valve repair. More particularly, the present invention relates to repair of valves of the heart and venous valves. Surgical repair of bodily tissues often involves tissue approximation and fastening of such tissues in the approximated arrangement. When repairing valves, tissue approximation includes coapting the leaflets of the valves in a therapeutic arrangement which may then be maintained by fastening or fixing the leaflets. Such coaptation can be used to treat regurgitation which most commonly occurs in the mitral valve. Mitral valve regurgitation is characterized by retrograde flow from the left ventricle of a heart through an incompetent mitral valve into the left atrium. During a normal cycle of heart contraction (systole), the mitral valve acts as a check valve to prevent flow of oxygenated blood back into the left atrium. In this way, the oxygenated blood is pumped into the aorta through the aortic valve. Regurgitation of the valve can significantly decrease the pumping efficiency of the heart, placing the patient at risk of severe, progressive heart failure. Mitral valve regurgitation can result from a number of different mechanical defects in the mitral valve or the left ventricular wall. The valve leaflets, the valve chordae which connect the leaflets to the papillary muscles, the papillary muscles or the left ventricular wall may be damaged or otherwise dysfunctional. Commonly, the valve annulus may be damaged, dilated, or weakened limiting the ability of the mitral valve to close adequately against the high pressures of the left ventricle. The most common treatments for mitral valve regurgitation rely on valve replacement or repair including leaflet and annulus remodeling, the latter generally referred to as valve annuloplasty. A recent technique for mitral valve repair which relies on suturing adjacent segments of the opposed valve leaflets together is referred to as the “bow-tie” or “edge-to-edge” technique. While all these techniques can be very effective, they usually rely on open heart surgery where the patient's chest is opened, typically via a sternotomy, and the patient placed on cardiopulmonary bypass. The need to both open the chest and place the patient on bypass is traumatic and has associated high mortality and morbidity. For these reasons, it would be desirable to provide alternative and additional methods, devices, and systems for performing the repair of mitral and other cardiac valves. Such methods, devices, and systems should preferably not require open chest access and be capable of being performed either endovascularly, i.e., using devices which are advanced to the heart from a point in the patient's vasculature remote from the heart or by a minimally invasive approach. Further, such devices and systems should provide features which allow repositioning and optional removal of a fixation device prior to fixation to ensure optimal placement. In addition, such devices and systems should provide features that assist in secure engagement of the targeted tissue (e.g. leaflet or other targeted structure) at the time of placement and over time (e.g. tissue in growth, maximal surface area of engagement). The methods, devices, and systems would also be useful for repair of tissues in the body other than heart valves. At least some of these objectives will be met by the inventions described hereinbelow. 2. Description of the Background Art Minimally invasive and percutaneous techniques for coapting and modifying mitral valve leaflets to treat mitral valve regurgitation are described in PCT Publication Nos. WO 98/35638; WO 99/00059; WO 99/01377; and WO 00/03759. Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci et al. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al. (1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgical procedures for performing “edge-to-edge” or “bow-tie” mitral valve repair where edges of the opposed valve leaflets are sutured together to lessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med. 331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg. 112:238-247 are review articles discussing the nature of and treatments for dilated cardiomyopathy. Mitral valve annuloplasty is described in the following publications. Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996) Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J. 129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmental annuloplasty for mitral valve repair is described in Ricchi et al. (1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty is described in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268; Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989) Ann. Thorac. Surg. 48:670-676. Percutaneous transluminal cardiac repair procedures are described in Park et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am. Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc. Diagn. 23:257-262. Endovascular cardiac valve replacement is described in U.S. Pat. Nos. 5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854. See also U.S. Pat. No. 3,671,979 which describes a catheter for temporary placement of an artificial heart valve. Other percutaneous and endovascular cardiac repair procedures are described in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and PCT Publication No. WO 91/01689. Thoracoscopic and other minimally invasive heart valve repair and replacement procedures are described in U.S. Pat. Nos. 5,855,614; 5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725. BRIEF SUMMARY OF THE INVENTION The invention provides devices, systems and methods for tissue approximation and repair at treatment sites. The devices, systems and methods of the invention will find use in a variety of therapeutic procedures, including endovascular, minimally-invasive, and open surgical procedures, and can be used in various anatomical regions, including the abdomen, thorax, cardiovascular system, heart, intestinal tract, stomach, urinary tract, bladder, lung, and other organs, vessels, and tissues. The invention is particularly useful in those procedures requiring minimally-invasive or endovascular access to remote tissue locations. In some embodiments, the devices, systems and methods of the invention are adapted for fixation of tissue at a treatment site. Exemplary tissue fixation applications include cardiac valve repair, septal defect repair, vascular ligation and clamping, laceration repair and wound closure, but the invention may find use in a wide variety of tissue approximation and repair procedures. In a particularly preferred embodiment, the devices, systems and methods of the invention are adapted for repair of cardiac valves, and particularly the mitral valve, as a therapy for regurgitation. The invention enables two or more valve leaflets to be coapted using an “edge-to-edge” or “bow-tie” technique to reduce regurgitation, yet does not require open surgery through the chest and heart wall as in conventional approaches. In addition, the position of the leaflets may vary in diseased mitral valves depending upon the type and degree of disease, such as calcification, prolapse or flail. These types of diseases can result in one leaflet being more mobile than the other (e.g. more difficult to capture), and therefore more difficult to grasp symmetrically in the same grasp with the other leaflet. The features of the present invention allow the fixation devices to be adapted to meet the challenges of unpredictable target tissue geometry, as well as providing a more robust grasp on the tissue once it is captured. Using the devices, systems and methods of the invention, the mitral valve can be accessed from a remote surgical or vascular access point and the two valve leaflets may be coapted using endovascular or minimally invasive approaches. While less preferred, in some circumstances the invention may also find application in open surgical approaches as well. According to the invention, the mitral valve may be approached either from the atrial side (antegrade approach) or the ventricular side (retrograde approach), and either through blood vessels or through the heart wall. The fixation devices of the present invention each have a pair of distal elements (or fixation elements). In the main embodiments, each distal element has a first end, a free end opposite the first end, an engagement surface therebetween for engaging tissue and a longitudinal axis extending between the first and free end. The first ends of the at least two distal elements are movably coupled together such that the at least two distal elements are moveable to engage tissue with the engagement surfaces. Thus, the first ends are coupled together so that the distal elements can move between at least an open and closed position to engage tissue. Preferably, the engagement surfaces are spaced apart in the open position and are closer together and generally face toward each other in the closed position. Each distal element has a width measured perpendicular to its longitudinal axis and a length measured along its longitudinal axis. In one embodiment suitable for mitral valve repair, the fixed width across engagement surfaces (which determines the width of tissue engaged) is at least about 2 mm, usually 3-10 mm, and preferably about 4-6mm. In some situations, a wider engagement is desired wherein the engagement surfaces have a larger fixed width, for example about 2 cm. The engagement surfaces are typically configured to engage a length of tissue of about 4-10 mm, and preferably about 6-8 mm along the longitudinal axis. However, the size of the engagement surfaces may be varied in width and/or length, as will be described in later sections. The fixation device is preferably delivered to a target location in a patient's body by a delivery catheter having an elongated shaft, a proximal end and a distal end, the delivery catheter being configured to be positioned at the target location from a remote access point such as a vascular puncture or cut-down or a surgical penetration. In an alternative embodiment, the target location is a valve in the heart. Optionally, the fixation devices of the invention will further include at least one proximal element (or gripping element). Each proximal element and distal element will be movable relative to each other and configured to capture tissue between the proximal element and the engagement surface of the distal element. Preferably, the distal elements and proximal elements are independently movable but in some embodiments may be movable with the same mechanism. The proximal element may be preferably biased toward the engagement surface of the fixation element to provide a compressive force against tissue captured therebetween. In a first aspect of the present invention, fixation devices are provided that include at least two distal elements and an actuatable feature attached to at least one of the at least two distal elements. Actuation of the feature varies a dimension of at least one of the at least two distal elements which varies the size of its engagement surface. For example, in some embodiments, the actuatable feature is configured so that actuation varies the width of the distal element. In some of these embodiments, the actuatable feature comprises at least one loop which is extendable laterally outwardly in a direction perpendicular to the longitudinal axis. Thus, extension of the at least one loop increases the size of the engagement surface of the distal element, specifically the width. In others of these embodiments, the actuatable feature comprises at least one flap which is extendable laterally outwardly in a direction perpendicular to the longitudinal axis. And in still others, the actuatable feature comprises at least one pontoon which is expandable laterally outwardly in a direction perpendicular to the longitudinal axis. The pontoon may be expanded by inflation or any suitable means. In some embodiments, the actuatable feature is configured so that actuation varies the length of the distal element. In some of these embodiments, the actuatable feature comprises at least one loop which is extendable laterally outwardly from its free end along its longitudinal axis. Thus, extension of the at least one loop increases the size of the engagement surface of the distal element, specifically the length. In others of these embodiments, each of the distal elements comprises an elongate arm and the actuatable feature comprises an extension arm coupled with the elongate arm. The extension arm is extendable from the elongate arm to increase the length of the distal element. For example, in some instances the extension arm is coupled with the elongate arm by a cam such that rotation of the cam advances the extension arm along the longitudinal axis. Extension or retraction of the extension arm may be actuated by movement of the fixation device. For example, when each distal element is moveable from a closed position (wherein the engagement surfaces of the at least two distal elements are closer together) to an open position (wherein the engagement surfaces of the at least two distal elements are further apart), movement between the closed and open position may advance the extension arm of each distal element along its longitudinal axis. In a second aspect of the present invention, fixation devices are provided that include two pairs of distal elements, wherein the pairs of distal elements are in an opposed orientation so that the engagement surfaces of one pair faces the engagement surfaces of the other pair, and wherein the pairs of distal elements are moveable to engage tissue with the opposed engagement surfaces of the two pairs of distal elements. Thus, the fixation device includes four distal elements, the distal elements functioning in pairs so that each pair of distal elements engages a valve leaflet (in the case of the tissue comprising a valve leaflet) rather than a single distal element engaging each valve leaflet. In some embodiments, the distal elements of at least one of the two pairs are alignable so their longitudinal axes are substantially parallel. Alternatively or in addition, the distal elements of at least one of the two pairs may be rotatable laterally outwardly to a splayed position wherein their longitudinal axes substantially form an angle. In a third aspect of the present invention, accessories are provided which may be used with fixation devices of the present invention. Such accessories may provide benefits which are similar to increasing the width and/or length of the distal elements. Thus, such accessories may be used with fixation devices of fixed dimension or with fixation devices having distal elements of varying dimensions. In some embodiments, the accessory comprises a support coupleable with the fixation device, the support having at least two planar sections, each planar section configured to mate with an engagement surface of a distal element when coupled. In some embodiments, wherein the tissue comprises a valve leaflet, the support is configured so that each planar section is positionable against an upstream surface of the valve leaflet while each distal element is positionable against a downstream surface of the valve leaflet. Typically the fixation device is released from a delivery catheter yet temporarily maintained by a tether. Thus, in some embodiments, the support is configured to be advancable along the tether to the fixation device. The tether may be removed from the fixation device while the support is coupled to the fixation device. Thus, the fixation device and support may be left behind to maintain fixation of the tissue. In a fourth aspect of the present invention, a fixation device is provided having at least two distal elements wherein each of the at least two distal elements has a length along its longitudinal axis, and wherein the length of one of the at least two distal elements is longer than another of the at least two distal elements. In some embodiments, the fixation device has variable length distal elements, wherein each distal element is adjustable to a different length. In other embodiments, the fixation device has fixed length distal elements, wherein each distal element is formed to have a different length. And, in still further embodiments, the fixation device has both fixed and variable length distal elements. Other aspects of the nature and advantages of the invention are set forth in the detailed description set forth below, taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A-1C illustrate grasping of the leaflets with a fixation device, inversion of the distal elements of the fixation device and removal of the fixation device, respectively. FIG. 2 illustrates the position of the fixation device in a desired orientation relative to the leaflets. FIG. 3 illustrates another embodiment of the fixation device of the present invention. FIGS. 4A-4B , 5 A- 5 B, 6 A- 6 B, 7 A- 7 B illustrate embodiments of a fixation device in various possible positions during introduction and placement of the device within the body to perform a therapeutic procedure. FIGS. 8A-8B illustrate an embodiment of distal elements having variable width wherein one or more loops are extendable laterally outwardly. FIGS. 9A-9B illustrate an embodiment of distal elements having variable width wherein one or more flaps are extendable laterally outwardly. FIGS. 10A-10B illustrate an embodiment of distal elements having variable width wherein one or more pontoons are expandable laterally outwardly. FIGS. 11A-11B provide a perspective view of a fixation device having distal elements which are capable of moving to a splayed position. FIGS. 11C-11D provide a side view of the fixation device of FIGS. 11A-11B plicating tissue of a leaflet. FIGS. 12A-12B provide a top view of a fixation device having distal elements which are capable of moving to a splayed position. FIGS. 13A-13B illustrate an embodiment of distal elements having variable length wherein one or more loops are extendable outwardly. FIGS. 14A-14B , 15 illustrate embodiments of distal elements having variable length wherein the distal elements include extension arms. FIG. 16 illustrates an embodiment of the fixation device having distal elements of different lengths. FIGS. 17A-17B illustrate an embodiment of an accessory for use with fixation devices of the present invention. FIGS. 18A-18B illustrate an embodiment of distal elements which vary in length and width. FIGS. 19A-19C , 20 A- 20 C illustrate embodiments of a fixation device combining splaying and variable length distal elements. DETAILED DESCRIPTION OF THE INVENTION 1. Fixation Device Overview. The present invention provides methods and devices for grasping, approximating and fixating tissues such as valve leaflets to treat cardiac valve regurgitation, particularly mitral valve regurgitation. Grasping may be atraumatic which can provide a number of benefits. By atraumatic, it is meant that the devices and methods of the invention may be applied to the valve leaflets and then removed without causing any significant clinical impairment of leaflet structure or function. The leaflets and valve continue to function substantially the same as before the invention was applied. Thus, some minor penetration or denting of the leaflets may occur using the invention while still meeting the definition of “atraumatic”. This enables the devices of the invention to be applied to a diseased valve and, if desired, removed or repositioned without having negatively affected valve function. In addition, it will be understood that in some cases it may be necessary or desirable to pierce or otherwise permanently affect the leaflets during either grasping, fixing or both. In some of these cases, grasping and fixation may be accomplished by a single device. Although a number of embodiments are provided to achieve these results, a general overview of the basic features will be presented herein. Such features are not intended to limit the scope of the invention and are presented with the aim of providing a basis for descriptions of individual embodiments presented later in the application. The devices and methods of the invention rely upon the use of an interventional tool that is positioned near a desired treatment site and used to grasp the target tissue. In endovascular applications, the interventional tool is typically an interventional catheter. In surgical applications, the interventional tool is typically an interventional instrument. In some embodiments, fixation of the grasped tissue is accomplished by maintaining grasping with a portion of the interventional tool which is left behind as an implant. While the invention may have a variety of applications for tissue approximation and fixation throughout the body, it is particularly well adapted for the repair of valves, especially cardiac valves such as the mitral valve. Referring to FIG. 1A , an interventional tool 10 , having a delivery device, such as a shaft 12 , and a fixation device 14 , is illustrated having approached the mitral valve MV from the atrial side and grasped the leaflets LF. The mitral valve may be accessed either surgically or by using endovascular techniques, and either by a retrograde approach through the ventricle or by an antegrade approach through the atrium, as described above. For illustration purposes, an antegrade approach is described. The fixation device 14 is releasably attached to the shaft 12 of the interventional tool 10 at its distal end. When describing the devices of the invention herein, “proximal” shall mean the direction toward the end of the device to be manipulated by the user outside the patient's body, and “distal” shall mean the direction toward the working end of the device that is positioned at the treatment site and away from the user. With respect to the mitral valve, proximal shall refer to the atrial or upstream side of the valve leaflets and distal shall refer to the ventricular or downstream side of the valve leaflets. The fixation device 14 typically comprises proximal elements 16 (or gripping elements) and distal elements 18 (or fixation elements) which protrude radially outward and are positionable on opposite sides of the leaflets LF as shown so as to capture or retain the leaflets therebetween. The proximal elements 16 may be comprised of cobalt chromium, nitinol or stainless steel, and the distal elements 18 are may be comprised of cobalt chromium or stainless steel, however any suitable materials may be used. The fixation device 14 is coupleable to the shaft 12 by a coupling mechanism 17 . The coupling mechanism 17 allows the fixation device 14 to detach and be left behind as an implant to hold the leaflets together in the coapted position. In some situations, it may be desired to reposition or remove the fixation device 14 after the proximal elements 16 , distal elements 18 , or both have been deployed to capture the leaflets LF. Such repositioning or removal may be desired for a variety of reasons, such as to reapproach the valve in an attempt to achieve better valve function, more optimal positioning of the device 14 on the leaflets, better purchase on the leaflets, to detangle the device 14 from surrounding tissue such as chordae, to exchange the device 14 with one having a different design, or to abort the fixation procedure, to name a few. To facilitate repositioning or removal of the fixation device 14 the distal elements 18 are releasable and optionally invertible to a configuration suitable for withdrawal of the device 14 from the valve without tangling or interfering with or damaging the chordae, leaflets or other tissue. FIG. 1B illustrates inversion wherein the distal elements 18 are moveable in the direction of arrows 40 to an inverted position. Likewise, the proximal elements 16 may be raised, if desired. In the inverted position, the device 14 may be repositioned to a desired orientation wherein the distal elements may then be reverted to a grasping position against the leaflets as in FIG. 1A . Alternatively, the fixation device 14 may be withdrawn (indicated by arrow 42 ) from the leaflets as shown in FIG. 1C . Such inversion reduces trauma to the leaflets and minimizes any entanglement of the device with surrounding tissues. Once the device 14 has been withdrawn through the valve leaflets, the proximal and distal elements may be moved to a closed position or configuration suitable for removal from the body or for reinsertion through the mitral valve. FIG. 2 illustrates the position of the fixation device 14 in a desired orientation in relation to the leaflets LF. This is a short-axis view of the mitral valve MV from the atrial side, therefore, the proximal elements 16 are shown in solid line and the distal elements 18 are shown in dashed line. The proximal and distal elements 16 , 18 are positioned to be substantially perpendicular to the line of coaptation C. The device 14 may be moved roughly along the line of coaptation to the location of regurgitation. The leaflets LF are held in place so that during diastole, as shown in FIG. 2 , the leaflets LF remain in position between the elements 16 , 18 surrounded by openings O which result from the diastolic pressure gradient. Advantageously, leaflets LF are coapted such that their proximal or upstream surfaces are facing each other in a vertical orientation, parallel to the direction of blood flow through mitral valve MV. The upstream surfaces may be brought together so as to be in contact with one another or may be held slightly apart, but will preferably be maintained in the substantially vertical orientation in which the upstream surfaces face each other at the point of coaptation. This simulates the double orifice geometry of a standard surgical bow-tie repair. Color Doppler echo will show if the regurgitation of the valve has been reduced. If the resulting mitral flow pattern is satisfactory, the leaflets may be fixed together in this orientation. If the resulting color Doppler image shows insufficient improvement in mitral regurgitation, the interventional tool 10 may be repositioned. This may be repeated until an optimal result is produced wherein the leaflets LF are held in place. Once the leaflets are coapted in the desired arrangement, the fixation device 14 is then detached from the shaft 12 and left behind as an implant to hold the leaflets together in the coapted position. FIG. 3 illustrates an embodiment of a fixation device 14 . Here, the fixation device 14 is shown coupled to a shaft 12 to form an interventional tool 10 . The fixation device 14 includes a coupling member 19 and a pair of opposed distal elements 18 . The distal elements 18 comprise elongate arms 53 , each arm having a proximal end 52 rotatably connected to the coupling member 19 and a free end 54 . The free ends 54 have a rounded shape to minimize interference with and trauma to surrounding tissue structures. Each free end 54 may define a curvature about two axes, one being a longitudinal axis 66 of arms 53 . Thus, engagement surfaces 50 have a cupped or concave shape to surface area in contact with tissue and to assist in grasping and holding the valve leaflets. This further allows arms 53 to nest around the shaft 12 in a closed position to minimize the profile of the device. Arms 53 may be at least partially cupped or curved inwardly about their longitudinal axes 66 . Also, each free end 54 may define a curvature about an axis 67 perpendicular to longitudinal axis 66 of arms 53 . This curvature is a reverse curvature along the most distal portion of the free end 54 . Likewise, the longitudinal edges of the free ends 54 may flare outwardly. Both the reverse curvature and flaring minimize trauma to the tissue engaged therewith. Arms 53 further include a plurality of openings to enhance grip and to promote tissue ingrowth following implantation. The valve leaflets are grasped between the distal elements 18 and proximal elements 16 . In some embodiments, the proximal elements 16 are flexible, resilient, and cantilevered from coupling member 19 . The proximal elements are preferably resiliently biased toward the distal elements. Each proximal element 16 is shaped and positioned to be at least partially recessed within the concavity of the distal element 18 when no tissue is present. When the fixation device 14 is in the open position, the proximal elements 16 are shaped such that each proximal element 16 is separated from the engagement surface 50 near the proximal end 52 of arm 53 and slopes toward the engagement surface 50 near the free end 54 with the free end of the proximal element contacting engagement surface 50 , as illustrated in FIG. 3 . This shape of the proximal elements 16 accommodates valve leaflets or other tissues of varying thicknesses. Proximal elements 16 include a plurality of openings 63 and scalloped side edges 61 to increase grip on tissue. The proximal elements 16 optionally include frictional accessories, frictional features or grip-enhancing elements to assist in grasping and/or holding the leaflets. In some embodiments, the frictional accessories comprise barbs 60 having tapering pointed tips extending toward engagement surfaces 50 . It may be appreciated that any suitable frictional accessories may be used, such as prongs, windings, bands, barbs, grooves, channels, bumps, surface roughening, sintering, high-friction pads, coverings, coatings or a combination of these. Optionally, magnets may be present in the proximal and/or distal elements. It may be appreciated that the mating surfaces will be made from or will include material of opposite magnetic charge to cause attraction by magnetic force. For example, the proximal elements and distal elements may each include magnetic material of opposite charge so that tissue is held under constant compression between the proximal and distal elements to facilitate faster healing and ingrowth of tissue. Also, the magnetic force may be used to draw the proximal elements 16 toward the distal elements 18 , in addition to or alternatively to biasing of the proximal elements toward the distal elements. This may assist in deployment of the proximal elements 16 . In another example, the distal elements 18 each include magnetic material of opposite charge so that tissue positioned between the distal elements 18 is held therebetween by magnetic force. The fixation device 14 also includes an actuation mechanism 58 . In this embodiment, the actuation mechanism 58 comprises two link members or legs 68 , each leg 68 having a first end 70 which is rotatably joined with one of the distal elements 18 at a riveted joint 76 and a second end 72 which is rotatably joined with a stud 74 . The legs 68 may be comprised of a rigid or semi-rigid metal or polymer such as Elgiloy®, cobalt chromium or stainless steel, however any suitable material may be used. While in the embodiment illustrated both legs 68 are pinned to stud 74 by a single rivet 78 , it may be appreciated, however, that each leg 68 may be individually attached to the stud 74 by a separate rivet or pin. The stud 74 is joinable with an actuator rod 64 (not shown) which extends through the shaft 12 and is axially extendable and retractable to move the stud 74 and therefore the legs 68 which rotate the distal elements 18 between closed, open and inverted positions. Likewise, immobilization of the stud 74 holds the legs 68 in place and therefore holds the distal elements 18 in a desired position. The stud 74 may also be locked in place by a locking feature. In any of the embodiments of fixation device 14 disclosed herein, it may be desirable to provide some mobility or flexibility in distal elements 18 and/or proximal elements 16 in the closed position to enable these elements to move or flex with the opening or closing of the valve leaflets. This provides shock absorption and thereby reduces force on the leaflets and minimizes the possibility for tearing or other trauma to the leaflets. Such mobility or flexibility may be provided by using a flexible, resilient metal or polymer of appropriate thickness to construct the distal elements 18 . Also, the locking mechanism of the fixation device (described below) may be constructed of flexible materials to allow some slight movement of the proximal and distal elements even when locked. Further, the distal elements 18 can be connected to the coupling mechanism 19 or to actuation mechanism 58 by a mechanism that biases the distal element into the closed position (inwardly) but permits the arms to open slightly in response to forces exerted by the leaflets. For example, rather than being pinned at a single point, these components may be pinned through a slot that allowed a small amount of translation of the pin in response to forces against the arms. A spring is used to bias the pinned component toward one end of the slot. FIGS. 4A-4B , 5 A- 5 B, 6 A- 6 B, 7 A- 7 B illustrate embodiments of the fixation device 14 of FIG. 3 in various possible positions during introduction and placement of the device 14 within the body to perform a therapeutic procedure. FIG. 4A illustrates an embodiment of an interventional tool 10 delivered through a catheter 86 . It may be appreciated that the interventional tool 10 may take the form of a catheter, and likewise, the catheter 86 may take the form of a guide catheter or sheath. However, in this example the terms interventional tool 10 and catheter 86 will be used. The interventional tool 10 comprises a fixation device 14 coupled to a shaft 12 and the fixation device 14 is shown in the closed position. FIG. 4B illustrates a similar embodiment of the fixation device of FIG. 4A in a larger view. In the closed position, the opposed pair of distal elements 18 are positioned so that the engagement surfaces 50 face each other. Each distal element 18 comprises an elongate arm 53 having a cupped or concave shape so that together the arms 53 surround the shaft 12 and optionally contact each other on opposite sides of the shaft. This provides a low profile for the fixation device 14 which is readily passable through the catheter 86 and through any anatomical structures, such as the mitral valve. In addition, FIG. 4B further includes an actuation mechanism 58 . In this embodiment, the actuation mechanism 58 comprises two legs 68 which are each movably coupled to a base 69 . The base 69 is joined with an actuator rod 64 which extends through the shaft 12 and is used to manipulate the fixation device 14 . In some embodiments, the actuator rod 64 attaches directly to the actuation mechanism 58 , particularly the base 69 . However, the actuator rod 64 may alternatively attach to a stud 74 which in turn is attached to the base 69 . In some embodiments, the stud 74 is threaded so that the actuator rod 64 attaches to the stud 74 by a screw-type action. However, the rod 64 and stud 74 may be joined by any mechanism which is releasable to allow the fixation device 14 to be detached from shaft 12 . FIGS. 5A-5B illustrate the fixation device 14 in the open position. In the open position, the distal elements 18 are rotated so that the engagement surfaces 50 face a first direction. Distal advancement of the stud 74 relative to coupling member 19 by action of the actuator rod 64 applies force to the distal elements 18 which begin to rotate around joints 76 due to freedom of movement in this direction. Such rotation and movement of the distal elements 18 radially outward causes rotation of the legs 68 about joints 80 so that the legs 68 are directly slightly outwards. The stud 74 may be advanced to any desired distance correlating to a desired separation of the distal elements 18 . In the open position, engagement surfaces 50 are disposed at an acute angle relative to shaft 12 , and are preferably at an angle of between 90 and 180 degrees relative to each other. In one embodiment, in the open position the free ends 54 of arms 53 have a span therebetween of about 10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm. Proximal elements 16 are typically biased outwardly toward arms 53 . The proximal elements 16 may be moved inwardly toward the shaft 12 and held against the shaft 12 with the aid of proximal element lines 90 which can be in the form of sutures, wires, nitinol wire, rods, cables, polymeric lines, or other suitable structures. The proximal element lines 90 may be connected with the proximal elements 16 by threading the lines 90 in a variety of ways. When the proximal elements 16 have a loop shape, as shown in FIG. 5A , the line 90 may pass through the loop and double back. When the proximal elements 16 have an elongate solid shape, as shown in FIG. 5B , the line 90 may pass through one or more of the openings 63 in the element 16 . Further, a line loop 48 may be present on a proximal element 16 , also illustrated in FIG. 5B , through which a proximal element line 90 may pass and double back. Such a line loop 48 may be useful to reduce friction on proximal element line 90 or when the proximal elements 16 are solid or devoid of other loops or openings through which the proximal element lines 90 may attach. A proximal element line 90 may attach to the proximal elements 16 by detachable means which would allow a single line 90 to be attached to a proximal element 16 without doubling back and would allow the single line 90 to be detached directly from the proximal element 16 when desired. Examples of such detachable means include hooks, snares, clips or breakable couplings, to name a few. By applying sufficient tension to the proximal element line 90 , the detachable means may be detached from the proximal element 16 such as by breakage of the coupling. Other mechanisms for detachment may also be used. Similarly, a lock line 92 may be attached and detached from a locking mechanism by similar detachable means. In the open position, the fixation device 14 can engage the tissue which is to be approximated or treated. This embodiment is adapted for repair of the mitral valve using an antegrade approach from the left atrium. The interventional tool 10 is advanced through the mitral valve from the left atrium to the left ventricle. The distal elements 18 are oriented to be perpendicular to the line of coaptation and then positioned so that the engagement surfaces 50 contact the ventricular surface of the valve leaflets, thereby grasping the leaflets. The proximal elements 16 remain on the atrial side of the valve leaflets so that the leaflets lie between the proximal and distal elements. In this embodiment, the proximal elements 16 have frictional accessories, such as barbs 60 which are directed toward the distal elements 18 . However, neither the proximal elements 16 nor the barbs 60 contact the leaflets at this time. The interventional tool 10 may be repeatedly manipulated to reposition the fixation device 14 so that the leaflets are properly contacted or grasped at a desired location. Repositioning is achieved with the fixation device in the open position. In some instances, regurgitation may also be checked while the device 14 is in the open position. If regurgitation is not satisfactorily reduced, the device may be repositioned and regurgitation checked again until the desired results are achieved. It may also be desired to invert the fixation device 14 to aid in repositioning or removal of the fixation device 14 . FIGS. 6A-6B illustrate the fixation device 14 in the inverted position. By further advancement of stud 74 relative to coupling member 19 , the distal elements 18 are further rotated so that the engagement surfaces 50 face outwardly and free ends 54 point distally, with each arm 53 forming an obtuse angle relative to shaft 12 . The angle between arms 53 is preferably in the range of about 270 to 360 degrees. Further advancement of the stud 74 further rotates the distal elements 18 around joints 76 . This rotation and movement of the distal elements 18 radially outward causes rotation of the legs 68 about joints 80 so that the legs 68 are returned toward their initial position, generally parallel to each other. The stud 74 may be advanced to any desired distance correlating to a desired inversion of the distal elements 18 . Preferably, in the fully inverted position, the span between free ends 54 is no more than about 20 mm, usually less than about 16 mm, and preferably about 12-14 mm. In this illustration, the proximal elements 16 remain positioned against the shaft 12 by exerting tension on the proximal element lines 90 . Thus, a relatively large space may be created between the elements 16 , 18 for repositioning. In addition, the inverted position allows withdrawal of the fixation device 14 through the valve while minimizing trauma to the leaflets. Engagement surfaces 50 provide an atraumatic surface for deflecting tissue as the fixation device is refracted proximally. It should be further noted that barbs 60 are angled slightly in the distal direction (away from the free ends of the proximal elements 16 ), reducing the risk that the barbs will catch on or lacerate tissue as the fixation device is withdrawn. Once the fixation device 14 has been positioned in a desired location against the valve leaflets, the leaflets may then be captured between the proximal elements 16 and the distal elements 18 . FIGS. 7A-7B illustrate the fixation device 14 in such a position. Here, the proximal elements 16 are lowered toward the engagement surfaces 50 so that the leaflets are held therebetween. In FIG. 7B , the proximal elements 16 are shown to include barbs 60 which may be used to provide atraumatic gripping of the leaflets. Alternatively, larger, more sharply pointed barbs or other penetration structures may be used to pierce the leaflets to more actively assist in holding them in place. This position is similar to the open position of FIGS. 5A-5B , however the proximal elements 16 are now lowered toward arms 53 by releasing tension on proximal element lines 90 to compress the leaflet tissue therebetween. At any time, the proximal elements 16 may be raised and the distal elements 18 adjusted or inverted to reposition the fixation device 14 , if regurgitation is not sufficiently reduced. After the leaflets have been captured between the proximal and distal elements 16 , 18 in a desired arrangement, the distal elements 18 may be locked to hold the leaflets in this position or the fixation device 14 may be returned to or toward a closed position. It may be appreciated that the fixation devices 14 of the present invention may have any or all of the above described functions and features. For example, the fixation devices 14 may or may not be moveable to an inverted position. Or, the fixation devices 14 may or may not include proximal elements 16 . Thus, the above described aspects of the fixation devices 14 are simply various embodiments and are not intended to limit the scope of the present invention. 2. Variable Width Distal Elements. The width of one or more distal elements 18 of a fixation device 14 may be varied to increase the surface area and therefore increase the area of contact with tissue to be fixated, such as a valve leaflet. In some embodiments, the width is increased once the leaflets have been grasped. In other embodiments, the width is increased prior to grasping of the leaflets. Although it is typically desired to increase the width of the distal elements 18 to increase purchase size and distribute fixation forces, in some instances the variable width distal elements 18 may be used to decrease the width, either prior to leaflet grasping or while the leaflets are grasped. FIGS. 8A-8B illustrate an embodiment of distal elements 18 having a variable width. In this embodiment, each distal element 18 has one or more loops 100 which are extendable laterally outward in a direction perpendicular to longitudinal axis 66 . FIG. 8A illustrates the loops 100 in a retracted position, wherein the distal elements 18 each have a width determined by the size of the distal element 18 itself. In this embodiment, the loops 100 are disposed on a surface of the distal elements 18 opposite the engagement surfaces 50 when in the retracted position. However, it may be appreciated that the loops 100 may be disposed on the engagement surfaces 50 or within the distal elements 18 themselves. FIG. 8B illustrates the loops 100 in an expanded position wherein the loops 100 extend laterally outward in a direction perpendicular to longitudinal axis 66 . Expansion may be active or passive. The loops 100 may be comprised of any suitable material including wire, polymer, shape-memory alloy, Nitinol™, suture, or fiber, to name a few. Further, it may be appreciated that any number of loops 100 may be present, the loops 100 may extend any distance and the loops 100 may expand on one side of a distal element and not the other. FIGS. 9A-9B illustrate another embodiment of a fixation device 14 having distal elements 18 of variable width; here, the fixation device 14 is shown grasping a leaflet LF. In this embodiment, each distal element 18 has one or more flaps 104 which are extendable laterally outward in a direction perpendicular to longitudinal axis 66 . FIG. 9A illustrates the flaps 104 in a retracted position wherein the flaps 104 are substantially disposed within the distal elements 18 themselves. It may be appreciated however that the flaps 104 may be folded or curved so that the flaps are substantially disposed on the engagement surfaces 50 or on a surface of the distal elements 18 opposite the engagement surfaces 50 . FIG. 9B illustrates the flaps 104 in an expanded position wherein the flaps 104 extend laterally outward in a direction perpendicular to longitudinal axis 66 . Expansion may be active or passive. The flaps 104 may be comprised of any suitable material including polymer, mesh, metal, shape-memory alloy or a combination of these, to name a few. Further, it may be appreciated that any number of flaps 104 may be present, the flaps 104 may extend any distance and the flaps 104 may expand on one side of a distal element and not the other. FIGS. 10A-10B illustrate yet another embodiment of a fixation device 14 having distal elements 18 of variable width. In this embodiment, each distal element 18 has one or pontoons 108 which are expandable laterally outward in a direction perpendicular to longitudinal axis 66 . FIG. 10A provides a perspective view of a fixation device 14 having expandable pontoons 108 wherein the pontoons 108 are in an expanded state. FIG. 10B provides a side view of the fixation device 14 of FIG. 10B . Here, the increase in width of the distal element 18 due to the pontoon 108 may be readily seen. The pontoons 108 may be expanded by any means, such as by inflation with liquid or gas, such as by inflation with saline solution. Such expansion may be active or passive. The pontoons 108 may be comprised of any suitable material such as a flexible polymer or plastic. Further, it may be appreciated that any number of pontoons 108 may be present, the pontoons 108 may extend any distance and a pontoon 108 may expand on one side of a distal element and not the other. 3. Splayed Distal Elements. In some embodiments, the fixation device 14 includes additional distal elements 18 that assist in grasping of tissue, such as a valve leaflet. For example, the fixation device 14 may include four distal elements 18 wherein a pair of distal elements 18 grasp each side of the leaflet. The pairs of distal elements 18 may have any arrangement, however in some embodiments the distal elements 18 of each pair rotated laterally outwardly to a splayed position. This increases the area of contact with the tissue to be fixated and distributes the fixation forces across a broader portion of the tissue. Typically, the pairs of distal elements are splayed prior to grasping of the leaflets, however such splaying may be achieved after grasping. FIGS. 11A-11B provide a perspective view of an embodiment of a fixation device 14 having a first distal element 112 , a second distal element 114 , a third distal element 116 and a fourth distal element 118 . The distal elements 112 , 114 , 116 , 118 are arranged in pairs so that the first and second distal elements 112 , 114 are connected with one leg 68 and the third and fourth distal elements 116 , 118 are connected with the other leg 68 ′ allowing the distal elements to grasp in pairs. FIG. 11A illustrates the fixation device 14 in a closed position wherein the distal elements 112 , 114 , 116 , 118 are in substantially parallel alignment. FIG. 11B illustrates the fixation device 14 in an open position wherein the distal elements 112 , 114 , 116 , 118 are splayed apart. Here, the first and second distal elements 114 are rotated laterally outwardly so that the free ends 54 are moved away from each other. Such splaying may be achieved as a result of opening the fixation device 14 or may be achieved separately from the opening and closing mechanism. In this embodiment, the fixation device 14 includes two proximal elements 16 , each proximal element 16 facing a pair of distal elements. It may be appreciated that any number of proximal elements 16 , if any, may be present, including a corresponding proximal element for each distal element. Finally, the distal elements 112 , 114 , 116 , 118 may be splayed to separate the distal elements by any distance and the distance may be fixed or variable. Further, the distal elements 112 , 114 , 116 , 118 may be returned to the substantially parallel alignment. FIG. 11C provides a side view of the fixation device 14 of FIGS. 11A-11B capturing valve leaflets LF in a coapted position. The fixation device 14 is shown in the splayed position wherein the distal elements 112 , 114 are rotated laterally outwardly so that the free ends 54 are moved away from each other. It may be appreciated the proximal element 16 is disposed on the opposite side of the leaflet LF and therefore shielded from view. Return of the distal elements 112 , 114 toward the substantially parallel alignment, as illustrated in FIG. 11D , may capture tissue between the distal elements 112 , 114 , plicating the leaflet LF as shown. Such plication may be desired for optimal treatment of the diseased valve. FIGS. 12A-12B provide a top view of another embodiment of a fixation device 14 having a first distal element 112 , a second distal element 114 , a third distal element 116 and a fourth distal element 118 . FIG. 12A illustrates the fixation device 14 in a closed position wherein the distal elements 112 , 114 , 116 , 118 are in substantially parallel alignment. FIG. 12B illustrates the fixation device 14 in an open position wherein the distal elements 112 , 114 , 116 , 118 are splayed apart. Here, the first and second distal elements 114 are rotated laterally outwardly so that the free ends 54 are moved away from each other. Again, such splaying may be achieved as a result of opening the fixation device 14 or may be achieved separately from the opening and closing mechanism. And, the distal elements 112 , 114 , 116 , 118 may be splayed to separate the distal elements by any distance and the distance may be fixed or variable. Further, the distal elements 112 , 114 , 116 , 118 may be returned to the substantially parallel alignment. Again, it may be appreciated that return of the distal elements toward the substantially parallel alignment may capture tissue between the distal elements, plicating the leaflet. 4. Variable Length Distal Elements. The length of one or more distal elements 18 of a fixation device 14 may be varied to increase the surface area and therefore increase the area of contact with tissue to be fixated, such as a valve leaflet. In some embodiments, the length is increased once the leaflets have been grasped. In other embodiments, the length is increased prior to grasping of the leaflets. Although it is typically desired to increase the length of the distal elements 18 to increase purchase size and distribute fixation forces, in some instances the variable length distal elements 18 may be used to decrease the length, either prior to leaflet grasping or while the leaflets are grasped. FIGS. 13A-13B illustrate an embodiment of distal elements 18 having a variable length. In this embodiment, each distal element 18 has one or more loops 100 which are extendable outwardly from the free ends 54 along longitudinal axis 66 . FIG. 13A illustrates the loops 100 in a refracted position, wherein the distal elements 18 each have a length determined substantially by the length of the distal element 18 itself. In this embodiment, the loops 100 are retracted within the distal elements 18 themselves. However, it may be appreciated that the loops 100 may be disposed on the engagement surfaces 50 or on a surface opposite the engagement surfaces 50 . FIG. 13B illustrates the loops 100 in an expanded position wherein the loops 100 extend outwardly along longitudinal axis 66 . Expansion may be active or passive. The loops 100 may be comprised of any suitable material including wire, polymer, shape-memory alloy, Nitinol™, suture, or fiber, to name a few. Further, it may be appreciated that any number of loops 100 may be present and the loops 100 may extend any distance. FIGS. 14A-14B illustrate another embodiment of a fixation device 14 having distal elements 18 of variable length. In this embodiment, the fixation device 14 includes a coupling member 19 and a pair of opposed distal elements 18 , wherein each distal element 18 is comprised of an elongate arm 53 which is coupled with an extension arm 130 . Each elongate arm 53 has a proximal end 52 rotatably connected to the coupling member 19 and a free end 54 . The extension arm 130 is coupled with the elongate arm 53 near the free end 54 to lengthen the distal element in the direction of a longitudinal axis 66 . Each elongate arm 53 is also coupled with a leg 68 , each leg 68 having a first end 70 which is rotatably joined with one of the distal elements 18 and a second end 72 which is rotatably joined with a base 69 . In this embodiment, the extension arm 130 is coupled with the elongate arm 53 by a cam 132 . The leg 68 is joined with the arm 53 and cam 132 at a first joint 134 and the extension arm 130 is joined with the cam 132 at a second joint 136 . Rotation of the cam 132 in the direction of arrows 138 , advances the extension arm 130 along the longitudinal axis 66 . FIG. 14B shows the cams 132 rotated so that the extension arms 130 are extended in the direction of arrows 140 . The cams 132 may rotate due to motion of the fixation device 14 between an open and closed position, or rotation of the cams 132 may occur due to actuation of a mechanism. The extension arms 130 may be comprised of any suitable material, particularly a material similar to that of the elongate arms 53 . Further, it may be appreciated the extension arms 130 may have any length and may extend any distance. FIG. 15 illustrates another embodiment of a fixation device 14 having distal elements 18 of variable length. In this embodiment, each distal element 18 comprises an elongate arm 53 coupled with an extension arm 130 . Each elongate arm 53 has a proximal end 52 rotatably connected to the coupling member 19 and a free end 54 . The extension arm 130 is coupled with the elongate arm 53 near the free end 54 to lengthen the distal element in the direction of a longitudinal axis 66 . Each elongate arm 53 is also coupled with a leg 68 , each leg 68 having a first end 70 which is rotatably joined with one of the distal elements 18 and a second end 72 which is rotatably joined with a base 69 . In this embodiment, each extension arm 130 is disposed within a corresponding elongate arm 53 and may be extended beyond the free end 54 by advancement out of the elongate arm 53 . Likewise, the extension arm 130 may be retracted back into the elongate arm 53 . In some embodiments, the extension arms 130 are extended by action of the fixation device 14 moving toward an open position and are retracted by action of the fixation device 14 moving toward a closed position. Extension and retraction may be active or passive and the extension arms 130 may be extended any distance. 5. Differing Length Distal Elements. In some instances, it may be desired to grasp or fix tissue or valve leaflets together with a fixation device 14 wherein the distal elements 18 are of differing length. This may be achieved with a fixation device 14 having variable length distal elements 18 , wherein each distal element 18 is adjusted to a different length. Or, this may be achieved with a fixation device 14 having distal elements 18 of fixed length, wherein each distal element 18 is formed to have a different length. An example of such a fixation device is illustrated in FIG. 16 . As shown, the fixation device 14 includes two distal elements 18 , each joined with a coupling member 18 and a leg 68 wherein actuation of the legs 68 move the distal elements 18 between at least an open and closed position. In this example, one of the distal elements 18 is shown to be longer than the other. The fixation device 14 may also include proximal elements 14 . Proximal elements 16 may be of the same dimensions or one may be longer than the other to correspond with the distal elements 18 to which they mate. 6. Accessories. One or more accessories may be used with the fixation devices 14 of the present invention to increase purchase size and distribute fixation forces. Thus, such accessories may provide benefits similar to increasing the width and/or length of the distal elements. Thus, such accessories may be used with fixation devices of fixed dimension or with fixation devices having distal elements of varying dimension. FIGS. 17A-17B illustrate an embodiment of an accessory 150 . In this embodiment, the accessory 150 comprises a support 152 which is positioned to support the tissue which is being grasped by the fixation device 14 . FIG. 17A illustrates valve leaflets LF being grasped by a fixation device 14 . The fixation device 14 includes a pair of distal elements 18 which are joined with a coupling member 19 and moveable between at least an open and closed position by a pair of legs 68 . In this embodiment, engagement surfaces 50 of the distal elements 18 contact the downstream surfaces of the leaflets LF. In this embodiment, the support 152 has at least two planar sections, each planar section configured to mate with an engagement surface of a distal element 18 when coupled. Typically, the fixation device 14 is released from a delivery catheter, yet maintained by a tether 154 , to determine if regurgitation has been sufficiently reduced. If additional support is desired, the support 152 is advanced down the tether 154 , as depicted in FIG. 17A , and positioned against the upstream surfaces of the leaflets, as depicted in FIG. 17B . The support 152 is then attached to the fixation device 14 and the tether 154 removed. 7. Combinations. Any of the above described features and accessories may be present in any combination in a fixation device of the present invention. For example, a fixation device 14 may have distal elements 18 that vary in width and in length, either simultaneously or independently. Or, the fixation device may have distal elements 18 that are splayable and vary in length or width or length and width, all of which may occur simultaneously or independently. Or, in another example, the fixation device 14 may have one distal element 18 which is longer than the other wherein one or both distal elements 18 vary in width. Further, mechanisms related to each feature may be present in any combination. For example, a fixation device 14 may have one distal element 18 that varies in width by action of a flap 104 and another distal element 18 that varies in width by action of a pontoon 108 . Still further, a fixation device 14 may include some distal elements 18 which have one or more of the above described features and some distal elements 18 which do not. FIGS. 18A-18B illustrate an embodiment of a fixation device 14 combining the features presented in FIGS. 8A-8B and FIGS. 13A-13B . In this embodiment, each distal element 18 has one or more loops 100 which are extendable laterally outward in a direction perpendicular to longitudinal axis 66 and extendable outward along longitudinal axis 66 . FIG. 18A illustrates the loops 100 in a retracted position, wherein the distal elements 18 each have a width and length substantially determined by the size of the distal element 18 itself. In this embodiment, some of the loops 100 are disposed on a surface of the distal elements 18 opposite the engagement surfaces 50 when in the retracted position. However, it may be appreciated that the loops 100 may be disposed on the engagement surfaces 50 or within the distal elements 18 themselves. FIG. 18B illustrates the loops 100 in an expanded position wherein the loops 100 extend laterally outward in a direction perpendicular to longitudinal axis 66 and outward along longitudinal axis 66 . Expansion may be active or passive. The loops 100 may be comprised of any suitable material including wire, polymer, shape-memory alloy, Nitinol™, suture, or fiber, to name a few. Further, it may be appreciated that any number of loops 100 may be present and the loops 100 may extend any distance. FIGS. 19A-19C illustrate an embodiment of a fixation device 14 combining splaying and variable length distal elements. FIG. 19A provides a perspective view of a fixation device 14 having four distal elements 18 . Each distal element 18 is connected with a coupling member 19 and a leg 68 , wherein actuation of the legs 68 move the distal elements 18 between at least an open and closed position. FIG. 19B provides a top view of the fixation device 14 of FIG. 19A in the open position illustrating the splaying of the distal elements 18 . In this embodiment, the distal elements 18 are fixed in a splayed position. When in the open position, the fixation device 14 can be positioned to grasp tissue, such as a valve leaflet. Transitioning to a closed position retracts the distal elements 18 as illustrated in FIG. 19C . Similarly, as mentioned above, tissue may be captured or “pinched” between the distal elements 18 . Further, retraction of the distal elements may drag the tissue inwardly. Together, such actions may assist in gathering up the leaflet to tighten the plication while also providing a more secure grasp on the captured tissue. FIGS. 20A-20C also illustrates an embodiment of a fixation device 14 combining splaying and variable length distal elements. FIG. 20A provides a top view of the fixation device 14 having four distal elements 18 . Again, each distal element 18 is connected with a coupling member 19 and a leg 68 , wherein actuation of the legs 68 move the distal elements 18 between at least an open and closed position. In FIG. 20A , the distal elements 18 are shown in a splayed arrangement. However, in this embodiment, the distal elements 18 are not fixed in the splayed arrangement. FIG. 20B illustrates the distal elements 18 rotating to a parallel arrangement. Thus, when in the open position, the distal elements 18 can move between a parallel arrangement and a splayed arrangement prior to grasping tissue. Transitioning to a closed position retracts the distal elements 18 as illustrated in FIG. 20C . Although the foregoing invention has been described in some detail by way of illustration and example, for purposes of clarity of understanding, it will be obvious that various alternatives, modifications and equivalents may be used and the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.

Devices, systems and methods are provided for tissue approximation and repair at treatment sites, particularly in those procedures requiring minimally-invasive or endovascular access to remote tissue locations. Fixation devices are provided to fix tissue in approximation with the use of distal elements. In some embodiments, the fixation devices have at least two distal elements and an actuatable feature wherein actuation of the feature varies a dimension of the at least two distal elements. In other embodiments, the fixation devices have at least two pairs of distal elements wherein the pairs of distal elements are moveable to engage tissue between opposed pairs of distal elements. Systems are also provided having fixation devices and accessories.

RELATED APPLICATION [0001] This is a continuation-in-part of application Ser. No. 09/491,426, filed Jan. 26, 2000. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention is broadly concerned with calcium-enriched compositions and methods of supplementing food products with those compositions. More particularly, the inventive compositions include respective sources of phosphate ions, citrate ions, and calcium ions, a metal hydroxide, and water. The compositions have high solids contents and are in the form of substantially uniform, colloidal suspensions in which a high percentage of the available calcium ions remains dispersed. [0004] 2. Description of the Prior Art [0005] The food industry has long sought stable, water-dispersible forms of calcium which would allow significant amounts of calcium to be introduced into food products without substantially increasing the bulk of the product. To be effective in this context, the calcium-containing substances must be essentially odorless, colorless, tasteless, and producible at a relatively low cost. In addition, these substances must be stable under the extreme conditions dictated by formulation, processing, and storage of the food products. [0006] Numerous food products would benefit from calcium enrichment. For example, animal milk products (particularly those formed from cow's milk) are already considered to be a good dietary source of calcium. However, these products contain only limited quantities of calcium in each serving, requiring the average person to consume a large portion of the product to obtain the recommended daily allowance (RDA) of calcium. Furthermore, some people have medical conditions (e.g., osteoporosis) which require the consumption of calcium beyond that required for others. Therefore, supplemental products which increase the amount of calcium in each serving of milk products at a low cost and without negatively affecting the quality of the milk product are always in demand. [0007] Many people do not consume animal milk products for one reason or another. For example, some people are allergic to these products and cannot safely consume them. There are other people who simply do not consume animal milk products as a lifestyle choice. Many of these people turn to soy milk as an alternative to animal milk products. While the taste and odor of soy milk has been substantially improved in recent years, soy milk does not naturally contain a significant amount of calcium. Thus, soy milk must be supplemented with calcium in order to provide many of these people with at least some calcium in their diets. [0008] Certainly, many calcium supplements have been attempted in the past. The majority of the prior art calcium-enriched products are deficient in that they have extremely low solids contents, leading to products which are mostly water and is thus costly to ship and store. However, when the moisture levels of these products are reduced in order to make shipping and storing more feasible, the calcium generally precipitates out of solution, forming an unappealing sediment. SUMMARY OF THE INVENTION [0009] The present invention overcomes these problems by broadly providing calcium-enriched compositions having high solids contents of soluble calcium with very little or no sedimentation. It has been discovered that the order of mixing the various ingredients in forming the composition is critical, and thus, modifying the mixing order followed in prior art methods dramatically increases the solids contents of soluble calcium in the composition. [0010] In more detail, the inventive compositions comprise a source of phosphate ions, a source of citrate ions, a source of calcium ions, a quantity of a metal hydroxide, and water. The source of phosphate ions should be provided in sufficient quantities so that the composition comprises from about 5-28% by weight phosphate ions, and preferably from about 8-23% by weight phosphate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of phosphate ions are phosphoric and polyphosphoric acids. [0011] The source of citrate ions should be present in the composition at such a level that the composition comprises from about 5-32% by weight citrate ions, and preferably from about 8-25% by weight citrate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of citrate ions are those selected from the group consisting of citric acid, calcium citrate, potassium citrate, and mixtures thereof, with citric acid being the most preferred source of citrate ions. [0012] In combination with the foregoing citrate and phosphate ion concentrations, each of these concentrations should also be such that the molar ratio of citrate ions to phosphate ions is from about 1.0:1.35 to about 1.0:2.35, and preferably from about 1.0:1.75 to about 1.0:1.95. These ratios are important for obtaining the improved solids contents and calcium yields of the inventive compositions. [0013] The source of calcium ions should be utilized in sufficient quantities to provide from about 2.5-16.5% by weight calcium ions, and preferably from about 4-15% by weight calcium ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferred sources of calcium ions are those selected from the group consisting of calcium hydroxide, calcium carbonate, calcium oxide, and mixtures thereof. The most preferred sources of calcium ions are calcium hydroxide and calcium oxide. [0014] The metal hydroxide is preferably included in sufficient quantities in the compositions such that the compositions comprise from about 0.5-7.5% by weight of the metal ions, and more preferably from about 0.8-6.5% by weight of the metal ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferably the metal hydroxide is an alkali metal hydroxide, with potassium hydroxide and sodium hydroxide being particularly preferred. [0015] Finally, water should be included in the composition at a level of from about 0.1-80% by weight, and preferably from about 2.0-50% by weight, based upon the total weight of the composition taken as 100% by weight. [0016] The inventive compositions are prepared by forming a precursor mixture comprising the source of citrate ions, the source of calcium ions, the metal hydroxide, and water. The order of addition of these ingredients during this stage is not critical, although it is preferred that the calcium ion source be added to the water initially, followed by the addition of the metal hydroxide and then the citrate ion source to the resulting mixture. Preferably, mixing is carried out on the intermediate mixtures for about 2-3 minutes after the addition of each ingredient. [0017] The source of phosphate ions is then added to the precursor mixture, followed by intense mixing and heating of the resulting composition to a temperature of about 190-210° F., and preferably about 200° F. until the desired solids content is achieved. That is, the solids content of the inventive compositions is at least about 20% by weight, preferably at least about 35% by weight, and more preferably at least about 45% by weight, based upon the total weight of the composition taken as 100% by weight. It has been discovered that adding the source of phosphate ions to the formed precursor mixture (i.e., after the source of citrate ions has been mixed with the other ingredients) dramatically increases the level of soluble solids in the composition, making these high solids contents obtainable. This improvement substantially lessens the quantity of moisture in the composition that must be shipped and stored and, therefore, will lessen the cost of shipping and storing the compositions. [0018] The resulting compositions have a pH of from about 5.5-7.5, and preferably from about 6.5-7.0. Furthermore, the final compositions comprise at least about 3% by weight calcium ions, and preferably at least about 6% by weight calcium ions, based upon the total weight of the composition taken as 100% by weight. This high calcium ion concentration is a result of the fact that at least about 70%, preferably at least about 80%, and more preferably at least about 90% of the theoretically available quantity of calcium ions will remain dispersed in the unshaken composition (i.e., a composition that has been maintained essentially motionless for at least about 2 days) at ambient temperatures. [0019] In applications where it is desired to produce a dry, reconstitutable product, it is generally preferred to subject the above-described aqueous composition to a drying process (e.g., spray drying or drum drying) until the moisture in the product has been reduced to a level of less than about 5% by weight, and preferably less than about 1% by weight, based upon the total weight of the composition taken as 100% by weight. The resultant solid powder, flake, or granular product can then be reconstituted in aqueous media by mixing it with water at levels of 1 part product with from about 1-4 parts water to form a composition which will exhibit substantially identical properties as those described above with respect to the original aqueous composition. [0020] It will be appreciated that the inventive compositions (either in the concentrated or dried forms) are well-suited for supplementing food products with calcium. Preferred food products which can be supplemented with the calcium-enriched compositions include: dairy products such as milk (e.g., cow's milk) and sour cream; imitation dairy products such as soy milk; soy-based products (e.g., tofu); beverages such as coffee, tea, water, fruit juices, vegetable juices, and other carbonated or non-carbonated beverages; soups; infant foods (e.g., infant formula, baby food); and pureed foods (e.g., applesauce). Other preferred food products include animal foods (e.g., dog food, cat food), mineral or nutritional supplements, mineral tonics, condiments, syrup, sauces (e.g., spaghetti sauce), and dessert products (e.g., pudding, ice cream, whipped topping). Those skilled in the art will appreciate that virtually any product, food or otherwise, in need of calcium supplementation can be enriched according to the invention. [0021] Advantageously, these food products can be supplemented by simply mixing the composition (either aqueous or dried) with the food product under ambient conditions. The supplemented products can be formulated to provide at least 100% of the RDA of calcium (i.e., 1000 mg of calcium ions per day is the RDA, thus, 1000 mg of calcium ions per quart of product would provide 100% of the RDA) or as much as 200% of the RDA of calcium, depending on the serving size. Thus, the food product can be supplemented to contain at least about 100 mg, preferably at least about 500 mg, and more preferably at least about 1000 mg, more calcium ions per serving (e.g., per liter or per gram of food product) than would otherwise be present in the non-supplemented product. This is preferably accomplished by mixing from about 12-60 cc of the aqueous composition or from about 6.0-12.0 g of the dried composition with each liter of food product to be supplemented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES [0022] The following examples set forth preferred methods in accordance with the invention. It is to be understood, however, that these examples are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention. Example 1 [0023] The ingredients of Table 1 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.35 and apH of 6.0. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 1 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 68.07 — —   1705 calcium hydroxide 2 6.89 2.33 2.29 172.5 45% KOH 3 10.10 2.03 2.00 252.9 solution citric acid, anhydrous 4 7.79 1.01 1.00 195.0 75% phosphoric acid 5 7.16 1.37 1.35 179.4 solution [0024] The resulting high percent solids final product was a very thick and viscous cream. At a 10% dilution, the product was a colloidal suspension with a trace of sediment being present at the bottom of the container after sitting overnight. Table 2 sets forth the concentrations of the ingredients at various percent solids formulations. Table 3 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 2 As 24.59% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.72% a 3.03% 5.30% 15.15% b Potassium 1.42% 1.16% 2.03% 5.80% b Citrate 7.66% 6.23% 10.90% 31.15% b Phosphate 5.21% 4.23% 7.41% 21.17% b [0025] [0025] TABLE 3 Property Value pH 6.0 % solids 31.0% a % calcium 4.9% a % yield 90.7% b Example 2 [0026] The ingredients of Table 4 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.35 and a pH of 6.7. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 4 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 66.89 — —   5800 calcium 2 6.76 7.92 2.29 586.6 hydroxide 45% KOH 3 11.67 8.12 2.00 1011.7 solution citric acid, 4 7.65 3.45 1.00 663.0 anhydrous 75% 5 7.03 4.67 1.35 610.0 phosphoric acid solution [0027] The resulting high percent solids final product was a very thick, viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 5 sets forth the concentrations of the ingredients at various percent solids formulations. Table 6 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 5 As 24.94% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.66% a 2.93% 5.13% 14.67% b Potassium 1.65% 1.32% 2.31% 6.60% b Citrate 7.53% 6.03% 10.56% 30.18% b Phosphate 5.11% 4.10% 7.18% 20.50 b [0028] [0028] TABLE 6 Property Value pH 6.7 % solids 52.5% a % calcium 7.2% a % yield 93.5% b Example 3 [0029] The ingredients of Table 7 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.35 and a pH of 7.4. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 7 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 66.09 — — 1160 calcium 2 6.68 1.58 2.29 117.3 hydroxide 45% KOH 3 12.68 1.79 2.59 222.6 solution citric acid, 4 7.56 0.69 1.00 132.6 anhydrous 75% 5 6.99 0.94 1.35 122.6 phosphoric acid solution [0030] The resulting high percent solids final product was a viscous, colloidal liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 8 sets forth the concentrations of the ingredients at various percent solids formulations. Table 9 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 8 As 25.17% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.62% a 2.88% 5.03% 14.38% b Potassium 1.79% 1.42% 2.49% 7.11% b Citrate 7.44% 5.91% 10.34% 29.54% b Phosphate 5.08% 4.04% 7.06% 20.18% b [0031] [0031] TABLE 9 Property Value pH 7.4 % solids 46.7% a % calcium 6.6% a % yield 99.0% b Example 4 [0032] The ingredients of Table 10 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.86 and a pH of 5.9. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 10 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 67.61 — — 7000 calcium 2 7.08 9.89 2.78 733.0 hydroxide 45% KOH 3 10.39 8.63 2.43 1076.2 solution citric acid, 4 6.59 3.55 1.00 682.5 anhydrous 75% 5 8.33 6.60 1.86 862.2 phosphoric acid solution [0033] The resulting high percent solids final product was a very viscous liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 11 sets forth the concentrations of the ingredients at various percent solids formulations. Table 12 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 11 As 24.59% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.83% a 3.12% 5.45% 15.58% b Potassium 1.47% 1.19% 2.09% 5.97% b Citrate 6.49% 5.28% 9.24% 26.39% b Phosphate 6.05% 4.92% 8.61% 24.62% b [0034] [0034] TABLE 12 Property Value pH 5.9 % solids 38.6% a % calcium 6.4% a % yield 95.0% b Example 5 [0035] The ingredients of Table 13 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.86 and a pH of 6.8. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 13 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 66.40 — — 5600 calcium 2 6.96 7.92 2.79 586.6 hydroxide 45% KOH 3 12.00 8.12 2.86 1011.7 solution citric acid, 4 6.47 2.84 1.00 546.0 anhydrous 75% 5 8.18 5.28 1.86 689.9 phosphoric acid solution [0036] The resulting high percent solids final product was a very thick, viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 14 sets forth the concentrations of the ingredients at various percent solids formulations. Table 15 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 14 As 24.96% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.76% a 3.01% 5.27% 15.07% b Potassium 1.69% 1.36% 2.37% 6.78% b Citrate 6.37% 5.11% 8.94% 25.53% b Phosphate 5.95% 4.76% 8.33% 23.82% b [0037] [0037] TABLE 15 Property Value pH 6.8 % solids 44.2% a % calcium 5.63% a % yield 84.6% b Example 6 [0038] The ingredients of Table 16 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.86 and a pH of 7.6. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212 F until the desired percent solids was achieved. TABLE 16 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 69.77 — — 1413.0 calcium 2 6.05 1.65 2.79 122.5 hydroxide 45% KOH 3 11.43 1.86 3.14 231.5 solution citric acid, 4 5.61 0.59 1.00 113.7 anhydrous 75% 5 7.14 1.11 1.86 144.5 phosphoric acid solution [0039] The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with no sediment being present at the bottom of the container after sitting overnight. Table 17 sets forth the concentrations of the ingredients at various percent solids formulations. Table 18 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 17 As 22.9% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.27% a 2.86% 5.00% 14.28% b Potassium 7.95% 6.94% 12.15% 34.72% b Citrate 5.52% 4.82% 8.44% 24.10% b Phosphate 6.92% 6.05% 10.59% 30.25% b [0040] [0040] TABLE 18 Property Value pH 8.0 % solids 22.9% a % calcium 4.22% a % yield 99.0% b Example 7 [0041] The ingredients of Table 19 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:2.33 and a pH of 5.7. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 19 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 72.07 — — 6600 calcium 2 6.40 7.91 3.25 586.4 hydroxide 45% KOH 3 8.30 6.10 2.50 760.0 solution citric acid, 4 5.11 2.44 1.00 468.0 anhydrous 75% 5 8.12 5.69 2.33 743.2 phosphoric acid solution [0042] The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 20 sets forth the concentrations of the ingredients at various percent solids formulations. Table 21 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 20 As 21.34% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.46% a 3.25% 5.68% 16.23% b Potassium 1.17% 1.10% 1.92% 5.49% b Citrate 5.03% 4.71% 8.25% 23.57% b Phosphate 5.90% 5.53% 9.67% 27.64% b [0043] [0043] TABLE 21 Property Value pH 5.7 % solids 34.5% a % calcium 5.7% a % yield 86.4% b Example 8 [0044] The ingredients of Table 22 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:2.33 and a pH of 7.2. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 22 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 66.12 — — 5480 calcium 2 7.08 7.92 3.25 586.6 hydroxide 45% KOH 3 12.19 8.11 3.33 1010.7 solution citric acid, 4 5.65 2.44 1.00 468.2 anhydrous 75% 5 8.96 5.68 2.33 742.4 phosphoric acid solution [0045] The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container after sitting overnight. Table 23 sets forth the concentrations of the ingredients at various percent solids formulations. Table 24 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 23 As 24.93% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.83% a 3.07% 5.38% 15.36% b Potassium 1.72% 1.38% 2.42% 6.90% b Citrate 5.56% 4.46% 7.81% 22.31% b Phosphate 6.51% 5.22% 9.14% 26.12% b [0046] [0046] TABLE 24 Property Value pH 7.2 % solids 52.1% a % calcium 8.1% a % yield 90.0% b Example 9 [0047] The ingredients of Table 25 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:2.33 and a pH of 7.2. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 25 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 69.45 — — 6600 calcium 2 6.21 7.96 3.26 590.0 hydroxide 45% KOH 3 11.59 8.83 3.62 1101.3 solution citric acid, 4 4.94 2.44 1.00 469.0 anhydrous 75% 5 7.82 5.68 2.33 742.7 phosphoric acid solution [0048] The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 26 sets forth the concentrations of the ingredients at various percent solids formulations. Table 27 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 26 As 22.22% As 100% Ions solids As 20% solids As 35% solids solids Calcium 3.36% a 3.36% 5.29% 15.12% b Potassium 1.64% 1.47% 2.58% 7.36% b Citrate 4.86% 4.37% 7.65% 21.86% b Phosphate 5.68% 5.11% 8.95% 25.57% b [0049] [0049] TABLE 27 Property Value pH 7.2 % solids 34.9% a % calcium 6.0% a % yield 85.7% b [0050] In each of the following three examples (Examples 10-12) different types of ingredients were utilized. Example 10 [0051] In this example, 115% polyphosphoric acid was used in place of a 75% phosphoric acid solution. The ingredients of Table 28 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.86 and a pH of 7.0. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 115% polyphosphoric acid solution mixed with water), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 28 Order of Anhydrous Anhydrous Weight in Ingredients addition % by weight a moles molar ratio grams water 1 70.27 — — 1700 calcium 2 6.73 2.20 2.78 162.8 hydroxide 45% KOH 3 11.56 2.24 2.84 279.8 solution citric acid, 4 6.27 0.79 1.00 151.6 anhydrous 115% polyphos- 5 5.17 1.47 1.86 125.1 phoric acid solution + 200 ml of water from step 1 [0052] The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a slight amount of sediment being present at the bottom of the container after sitting overnight. Table 29 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 29 Property Value pH 7.0 % solids 24.5% a % calcium 3.64% a % yield 99.0% b Example 11 [0053] In this example, sodium hydroxide was used in combination with potassium hydroxide. The ingredients of Table 30 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.87 and a pH of 7.4. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 30 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 72.83 — — 1432.8 calcium 2 6.25 1.65 2.80 122.9 hydroxide 45% KOH 3 5.87 0.93 1.57 115.54 solution sodium 4 1.90 0.93 1.57 37.4 hydroxide citric acid, 5 5.78 0.59 1.00 113.8 anhydrous 75% 6 7.37 1.10 1.87 144.9 phosphoric acid solution [0054] The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 31 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 31 Property Value pH 7.4 % solids 20.3% a % calcium 3.45% a % yield 99.0% b Example 12 [0055] In this example, calcium carbonate was used instead of calcium hydroxide. The ingredients of Table 32 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.88 and a pH of 9.0. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid), the mixture was heated to a temperature of about 210° F. for 30 minutes, followed by further heating at 212° F. until the desired percent solids was achieved. TABLE 32 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 69.85 — — 1595 calcium 2 7.16 1.65 2.80 163.5 carbonate 45% KOH 3 11.63 2.13 3.60 265.4 solution citric acid, 4 5.00 0.59 1.00 113.9 anhydrous 75% 5 6.36 1.11 1.88 145.13 phosphoric acid solution [0056] The resulting high percent solids final product was a viscous liquid. At a 10% dilution, the product was a colloidal suspension with a slight amount of sediment being present at the bottom of the container after sitting overnight. Table 33 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 33 Property Value pH 9.0 % solids 20.6% a % calcium 2.98% a % yield 99.0% b Example 13 [0057] The ingredients of Table 34 were mixed together in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:1.67 and a pH of 6.5. The ingredients were added in 2-3 minute intervals. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 200° F. and mixing was continued for 30 minutes. Then, the mixture was further heated to 212° F. and stirring was continued until a 45% solids content was achieved. Mixing was carried out utilizing an INDCO mixer (INDCO, Inc., New Albany, Ind.). The 1000-gallon, jacketed mixer was equipped with a 2-speed, 3- to 6-horsepower, gear-head which drove a sweep agitator blade and a 10-horsepower motor belt drive that powered a 10-inch, design D, INDCO dispersion blade. TABLE 34 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 73.83 — — 1900.0 calcium 2 5.38 1870.11 2.59 138.6 hydroxide 45% KOH 3 9.29 1917.13 2.66 239.0 solution citric acid, 4 5.38 721.29 1.00 138.6 anhydrous 75% 5 6.12 1205.28 1.67 157.5 phosphoric acid solution [0058] The resulting high percent solids final product was a very thick viscous liquid. At a 10% dilution, the product was a colloidal suspension with a trace amount of sediment being present at the bottom of the container after sitting overnight. Table 35 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 35 Property Value pH 6.5 % solids 45.5% a % calcium 6.6% a % yield 98.4% b [0059] For the following two examples (Examples 14-15), low percent solids formulations with a citric acid:phosphoric acid ratio of 1.0:2.0 were prepared by varying the order of addition of the acids. Example 14 [0060] In this example, a prior art formulation (Formula 65 of U.S. Pat. No. 4,214,996) was prepared as described in that patent in order to compare that formulation's solids content and calcium level to those of the instant invention. The ingredients of Table 36 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:2.0. The ingredients were added in 2-3 minute intervals, with mixing being carried out for about 2 minutes after the addition of each ingredient. Upon the addition of the final component (i.e., the citric acid), the mixture was heated to a temperature of about 200° F. and mixing was continued for 30 minutes. TABLE 36 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 89.80 — — 5160 calcium 2 2.12 1.65 3.0 122.0 hydroxide 45% KOH 3 3.75 1.73 3.0 215.4 solution 75% 4 2.20 1.10 2.0 143.4 phosphoric acid solution citric acid, 5 1.84 0.55 1.0 105.6 anhydrous [0061] The resulting low percent solids final product was a white opaque suspension. At a 10% dilution, the product was a colloidal suspension with a substantial amount of sediment being present at the bottom of the container after sitting overnight. Table 37 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 37 Property Value pH 7.45 % solids 8.27% a % calcium 0.38% a % yield 34.5% b Example 15 [0062] This test was similar to that described in Example 14, except that the order of ingredient addition was modified so that phosphoric acid was added last. The ingredients of Table 38 were combined, with continuous mixing, in the order indicated to yield a calcium-enriched composition having a citric acid:phosphoric acid molar ratio of 1.0:2.0. The ingredients were added in 2-3 minute intervals, with mixing being carried out for about 2 minutes after the addition of each ingredient. Upon the addition of the final component (i.e., the 75% phosphoric acid solution), the mixture was heated to a temperature of about 200° F. and mixing was continued for 30 minutes (i.e., heating was not carried out to obtain a particular solids content). TABLE 38 Order of % by Anhydrous Anhydrous Weight in Ingredients addition weight a moles molar ratio grams water 1 89.68 — — 5110 calcium 2 2.14 1.65 3.0 122.2 hydroxide 45% KOH 3 3.80 1.74 3.0 216.3 solution citric acid, 4 1.86 0.55 1.0 105.7 anhydrous 75% 5 2.53 1.10 2.0 143.9 phosphoric acid solution [0063] The resulting low percent solids final product was a colloidal suspension with a moderate amount of sediment being present at the bottom of the container. Table 39 lists additional properties of the product, with the percent calcium determined by atomic absorption spectrophotometric assays. TABLE 39 Property Value pH 7.60 % solids 9.37% a % calcium 1.64% a % yield 99.0% b [0064] A comparison of Examples 14 and 15 indicate that the soluble calcium content of the prior art formulation is substantially lower than the soluble calcium content achieved when phosphoric acid is added as the last ingredient according to the instant invention. Example 16 Calcium Supplementation of Soy Milk [0065] In this example, samples of soy milk were supplemented with a calcium-enriched composition according to the instant invention. That is, an amount of a calcium-enriched composition as prepared in Example 5 was added to soy milk which had not been previously supplemented with calcium. In each of these instances, the calcium-enriched composition was added in sufficient quantities to give a theoretically expected yield of 98 mg of calcium ions per 100 g of the soy product. The supplemented products were then tested for the actual calcium content by atomic absorption spectrophotometric assays. These results are set forth in Table 40. TABLE 40 Actual calcium Commercially Expected calcium ion ion content (mg Ca/100 g available content (mg Ca/100 g product ± soy milk product) 10 mg) Furama chocolate 98 160 (shaken top portion) Furama plain 98 160 (unshaken top portion) Furama chocolate 98 160 (unshaken top portion) [0066] Next, commercially available, calcium-enriched soy products were obtained and tested for their actual calcium ion content. These results are shown in Table 41. TABLE 41 Expected calcium ion Actual calcium Commercially available content (mg Ca/100 g ion content soy milk product) a (mg Ca/100 g product) Silk plain (unshaken top 98 48 portion) b Silk plain (shaken 98 140 portion) b Soy Dream (unshaken 98 35 top portion) c Soy Dream (shaken top 98 89 portion) c [0067] As shown in Table 41, all of the products except the shaken, Silk plain soy milk had a lower actual calcium ion content than indicated on the label. This was particularly true when the product was not mixed prior to testing, indicating that the calcium was precipitating out of solution. This was not true with the soy milks enriched with the inventive compositions (see Table 40) which each provided high soluble calcium contents in the Furama, even without shaking of the product. Example 17 Calcium Supplementation of Dairy Products [0068] In this example, dairy products were supplemented with a calcium-enriched composition according to the invention and compared with control samples. That is, an amount of a calcium-enriched composition as prepared in Example 5 was added to cow's milk (Belfonte 2% fat milk, labeled as containing 30% of the RDA of calcium per cup or 300 mg of calcium per serving). The inventive composition was mixed with the milk in sufficient quantities to increase the calcium in the milk to about 50% of the RDA of calcium (about 500 mg of calcium per 8 ounces of milk). Three such samples were prepared and are hereinafter referred to as Samples B, E, and H, respectively. [0069] Three additional samples (referred to as Samples C, F, and I) were prepared with sufficient tricalcium phosphate to fortify the milk to about 50% of the RDA of calcium per serving. Samples A, D, and G were the control samples. [0070] Each of the samples was refrigerated and tested at various time intervals to determine the concentration of calcium in the sample. The tested portions of the samples were taken from the unshaken, top portions of the liquid. These results are shown in Table 42. TABLE 42 Expected Percent Sample Day 1 a Sample Day 7 a Sample Day 14 a Average Average Dispersed A 1200 D 1200 G 1100 1200 1200 100% B 2100 E 1900 H 2300 2100 2000 100% C 1200 F 1100 I 1200 1200 2000  55% [0071] The samples fortified according to the invention (i.e., Samples B, E, and H) had higher calcium concentrations than any of the other samples throughout the entire period of examination. Furthermore, samples B, E, and H achieved the expected, enriched levels of 2000 mg of calcium per quart of milk product. This is due to the fact that all of the calcium in Samples B, E, and H remained suspended while much of the tricalcium phosphate utilized in Samples C, F, and I settled to the bottom of the container. Thus, the latter samples fortified with tricalcium phosphate provided only 1200 mg of calcium per quart of milk product while the samples fortified with the inventive composition achieved the expected 2000 mg of calcium per quart of milk. Example 43 Bioavailability of Calcium in Supplement Milk [0072] In this example, a calcium salt in accordance with the invention was tested by feeding the salt in milk consumed during meals. [0073] Methods [0074] Eighteen adult men (coded R-001 through R-018, respectively) ranging in age from 23 to 59 years, were recruited from a volunteer pool, by word of mouth, and by telephone solicitation. (The target sample was 16 subjects and the sample was over-recruited slightly to allow for possible subject loss.) Potential subjects were screened to exclude major medical illnesses, possibly interfering regular medications, and extremes of weight for height. The targeted 16 triple studies were completed, and full data was obtained for the other two subjects as well. The mean age of the 18 subjects (±S.D.) was 42.2 y (±9.5 y). Although there was inevitably some fluctuation in weight over the 4-5 week course of the project, it tended to be very small. [0075] The design for the study was a randomized cross-over involving three test meals in each subject, spaced nominally two weeks apart. Subjects were randomly assigned to one of six sequences: mrc, mcr, rcm, rmc, cmr, or crm, where “m” stands for milk, “r” for the complex salt of the invention, and “c” for the combination of the two. Sequence randomization to the subjects was performed using the random number function of EXCEL. [0076] All tests were performed in the morning after an overnight fast of 9-12 hours' duration. All participants were requested to abstain from alcohol for at least 36 hours prior to testing. The first tests were separated by seven weeks. Stragglers who had intercurrent medical problems or schedule conflicts were studied out of the regular schedule. [0077] The meal consisted of buttered, ORC-baked, low calcium white bread, toasted, and water, tea or coffee (with artificial sweetener if desired). Commercial white bread is fortified with certain B-vitamins in the U.S., and the carrying agent for the vitamin mixture is commonly a calcium salt. Accordingly, a specially baked, unenriched white bread was used in order to minimize meal calcium sources other than that tested. Meals were used because interindividual variance in absorption is reduced and absorption is optimized under meal conditions. The tracer-labeled calcium source, either the salt of the invention, a serving of milk or the combination, was consumed at the mid-point of the breakfast. The labeled calcium load in all tests was 300 mg. This was provided by 262.8 g skim milk and by 3.72 g of the product of the invention (see below). In the test meal using the fortified milk, 150 mg of the Ca load came from the milk (131.4 g), and 150 mg from the labeled salt of the invention (1.86 g). Meal and fluid volume were held constant in all subjects by adding suitable quantities of deionized water, as needed. The doses of the inventive salt were individually weighed on a tared black plastic spoon, and the spoons were placed in the subjects' mouths. The spoons were thoroughly licked by the subjects. The black plastic background facilitated identification of any residue; licking was continued until there was no perceptible residue. [0078] For the tests of the combined source in Visit 1, the product of the invention was added to the milk 14 hours before feeding and the combination stored in the refrigerator. The resulting product, next morning, left a very viscous film on the serving container that was not possible to rinse off with water (usual method to ensure quantitative transfer of the dose into the subjects). Accordingly, the residue in the serving containers was removed in the laboratory and its radioactivity separately analyzed. These counts were then subtracted from the calculated tracer dose for each subject before calculating absorption from the measured serum level of tracer. In light of this difficulty, it was decided to give all subsequent combination product doses by co-ingestion, i.e., by feeding the product of the invention separately from the milk, without pre-mixing. Specifically, subjects drank approximately half the milk, then ingested 1.86 g of the salt, then immediately took the remainder of the milk. Mixing of the calcium sources, then, occurred in the stomach. [0079] Skim milk for the milk-only meal was labeled ˜16 hours prior to dosing, by adding to the individual servings a carefully measured, submicrogram quantity of high specific activity 45 CaCl 2 salt (Amersham, Oak Ridge, Ill.) dissolved in 5 ml deionized water. For the two meals containing the complex salt of the invention, the label was incorporated into the salt alone and was accomplished at the time of the synthesis of the salt itself, by adding high specific activity 45 CaCl 2 to the reaction mixture of the Ca(OH) 2 stage, prior to addition of the other reactants. [0080] The resulting product was analyzed and had the following characteristics: percent solids—46.63; percent Ca—8.07; and radioactivity. Two samples were taken for both stable and radioactive calcium analysis. The CV for calcium was 1.3%, and for specific radioactivity, 1.2%, indicating very satisfactory homogeneity of the product. [0081] [0081] 45 Ca was analyzed by liquid scintillation counting on a Packard Model No. 1900TR instrument (Packard Instrument Corporation, Meriden, Conn.) against suitable blank samples (for background) and counting standards prepared from the dosing stock solution. This method allows radioactivity in the serum samples to be expressed as a fraction of the ingested dose. By bracketing the unknowns with dose standards, decay was automatically adjusted with time. All counting vials were saved until the end of the study for reanalysis if needed to double-check outliers (not necessary in this instance). Stable calcium in serum and in the calcium sources was analyzed by atomic absorption spectrophotometry (AAnalyst 100, Perkin-Elmer, Norwalk, Conn.). [0082] Because 45 Ca is an isotope with a relatively long half life (163 days), it is necessary to correct the serum radioactivity values obtained at subsequent tests for residual radioactivity remaining from previous tests. This correction was accomplished by obtaining a blood sample prior to the test breakfast at the second and third sessions, analyzing the serum for its 45 Ca, and subtracting this count level from the values obtained five hours later, after feeding a new test dose. The correction is small, but if it were not made, values measured at second (and subsequent) tests would slightly over-estimate absorption. A further correction was undertaken when the f-hour time point was not precisely hit (usually because of difficult venipuncture). Measured counts were adjusted by use of a variable function of the time lapse factor based on extensive laboratory data describing the exponential character of tracer concentration versus time. [0083] True fractional absorption was measured from the radioactivity level in the 5-hour sample, using published algorithms (Heaney et al.; Estimation of true calcium absorption; Annals Int Med; 103:516-521 (1985) and Heaney et al.; Estimating true fractional calcium absorption; Letter to the Editor:, Annals Int Med; 108:905-906 (1988). Briefly, absorption fraction is given by: FxAbs =( SA 5 0 92373 )*[0.3537*( Ht 0 52847 )*( Wt 0 37213 )], [0084] in which FxAbs equals absorption fraction; SA 5 equals 5-hour serum calcium specific radioactivity (fraction of oral dose per gram calcium); Ht equals height (meters); and Wt equals weight (kilograms). The bracketed factor at the right of the equation serves, in effect, to adjust the measured SA 5 values for body size differences (i.e., different volumes of distribution). This calculation is not strictly necessary in a cross-over design, since the paired specific activity data contain the only significantly varying values between substances. Nevertheless, expressing the data as true fractional absorption facilitates comparison with other published reports. [0085] The foregoing algorithm has been explicitly calibrated for women. Since men have, on average, a higher proportion of body water per unit weight, this algorithm underestimates true absorption in them by ˜10-15%. However, since this project is designed as a within-subject comparison, this systematic departure from true fractional absorption has no effect on the conclusions. [0086] One subject (ID09) developed a febrile respiratory infection at the time of the scheduled third visit. The visit was postponed for one week at which time the subject was in good health. There were no adverse reactions to the products tested. [0087] Data were characterized by simple descriptive statistics, using the various functions supplied by EXCEL (Microsoft Corp., Redmond, Wash.) or by the Crunch 4.04 Statistical Package (Crunch Software Corp., Oakland, Calif.). Additionally, data were analyzed by ANOVA using SAS (SAS Institute, Cary, N.C.) employing treatment and order as possible independent variables. [0088] Results [0089] Table 43 presents the fractional absorption data for the three test substances, by subject. Across all 18 subjects, absorption fraction averaged 0.238 for the milk, 0.182 for the salt of the invention alone, and 0.223 for the combination of the labeled salt of the invention in milk. The mean (±SEM) within-subject difference between milk alone and milk fortified with the salt of the invention was −0.0146 (±0.0202), and between milk alone and the salt of the invention alone, −0.0561 (±0.0092). There was no significance to the small difference between milk alone and milk fortified with the salt of the invention. However, the difference between the salt of the invention alone and milk alone was highly significant. These results were also tested for an effect of study order and no effect was found. [0090] Two batches of the complex salt of the invention was used in this study. One was a sample supplied by the manufacturer at the time this project was designed (Lot C 151 XL), and the other was a batch synthesized in the laboratory. The two batches seemed to behave differently. The first batch remained fully stable at room temperature for several months, while the second developed visible particles (apparently crystals) on standing for the several weeks between synthesis and the final test day. (This made dose aliquotting difficult for the second and third test days, because the product was no longer physically homogeneous, but was corrected by stirring thoroughly before taking the dose aliquots.) [0091] Also, as noted under Methods above, the combination of milk and the product of the invention became very viscous when stored in the refrigerator overnight. (This was not true at three hours, at which time the combination still exhibited gross pourability comparable to milk alone.) This apparently did not happen to product prepared by this manufacturer. [0092] Because the combination was pre-mixed for only one-third of the subjects, any reaction taking place between the milk matrix and the fortificant would not have occurred in the two-thirds of the subject who received the two sources concurrently (but not pre-mixed). The fractional absorption values comparing the two dosing methods for the combination were observed for the possibility of an effect. Those receiving the pre-mixed product absorbed significantly less efficiently than those ingesting the two products without pre-mixing (0.1634 vs. 0.2531). However, the subjects ingesting the pre-mixed product were not a random sample of the combination dosing group, and, as it turned out, the subjects absorbed the milk calcium somewhat less efficiently as well (0.214 vs. 0.25). [0093] Discussion [0094] These results demonstrate that the complex salt of the invention, when ingested by itself in the batch tested, was absorbed at about 76% the efficiency of the same quantity of calcium ingested as milk. When the product of the invention was co-ingested with milk, keeping total calcium load constant and confining the analysis to the same 12 subjects for both sources, absorption was identical for the two sources (0.2495 for milk alone, vs 0.2510 for the co-ingested combination). In those same 12 subjects, absorption from the salt of the invention ingested alone was still significantly lower (0.1919). Thus, eliminating the possibly confounding effect of the pre-mixed source, and confining the statistical analysis to those subjects dosed only by co-ingesting for the combination, the same conclusions are reached: milk calcium and the salt of the invention absorbed identically while the salt of the invention alone is less well absorbed. [0095] This finding is unusual, in that more commonly the food matrix, if it has any effect at all, reduces the absorbability of an added product. The opposite appears to be the case here. [0096] While the salt of the invention by itself, was not as bioavailable as milk calcium, the actual difference was not large. to achieve the same quantity of calcium absorbed, one need only ingest ˜30% more of the salt of the invention. TABLE 43 Individual Values for Absorption Fraction for the Three Sources Milk Milk + Inventive Salt Inventive Salt Alone ID Ht Order Wt Cas Absfx Order Wt Cas Absfx Order Wt Ca 5 Absfx 001 169.5 2 165.5 9.59 0.2129 1 168.5 9.58 0.2064 3 164.0 10.06 0.1727 002 183.1 3 226.0 9.74 0.2155 2 223.0 9.45 0.2271 1 220.5 9.32 0.1584 003 182.2 1 212.5 9.64 0.2603 3 213.5 9.85 0.3629 2 212.0 10.03 0.1751 004 179.7 1 198.5 9.33 0.2856 2 195.5 9.81 0.1827 3 199.0 10.03 0.1990 005 191.2 2 216.0 9.92 0.1712  1* 214.0 9.80 0.2997 3 215.0 9.79 0.1675 006 171.5 1 182.5 10.17 0.2390 2 183.5 10.13 0.2043 3 184 0 10.13 0.1499 007 185.0 2 194.0 10.04 0.1893 1 195.0 10.19 0.2834 3 193.5 10.34 0.1808 008 182.5 1 219.5 10.23 0.2289 3 217.5 9.85 0.2685 2 219.0 10.28 0.2040 009 160.9 1 152.0 9.75 0.2261 3 150.5 10.03 0.2769 2 153.0 9.77 0.1748 010 177.3 2 197.5 9.56 0.1569  1* 193.5 9.34 0.1640 3 195.5 9.64 0.1412 011 173.7 1 200.5 9.88 0.3286 3 199.5 9.74 0.2273 2 204.0 9.59 0.2039 012 177.3 2 173.5 9.89 0.3047 3 175.0 9.91 0.2295 1 175.5 9.67 0.2101 013 167.2 3 217.0 9.92 0.3304  1* 213.5 9.91 0.1955 2 214.5 9.74 0.2892 014 187.7 3 229.5 9.78 0.2739 2 229.5 9.56 0.3493 1 226.0 9.89 0.2465 015 176.1 3 169.5 9.32 0.2005  1* 169.0 9.70 0.1535 2 169.0 9.53 0.1422 016 186.7 3 178.5 9.72 0.1827  1* 180.0 9.42 0.0765 2 180.5 9.40 0.1088 017 179.8 3 213.5 9.43 0.2448  1* 212.0 9.54 0.0912 2 213.0 9.31 0.1190 018 161.3 1 174.0 9.62 0.2298 2 175.0 9.37 0.2195 3 177.0 9.43 0.2275 Mean 177.4 195.6 9.75 0.2378 194.9 9.73 0.2232 195.3 9.78 0.1817 St Dev 8.7 23.1 0.259 0.0512 22.2 0.256 0.0768 21.8 0.319 0.0449 N 18 18 18 18 18 18 18 18 18 18

An improved calcium-enriched composition and method of supplementing food products with the composition are provided. Broadly, the compositions include respective sources of phosphate ions, citrate ions, and calcium ions, metal hydroxides, and water, with the molar ratio of citrate ions to phosphate ions in the composition being from about 1.0:1.35 to about 1.0:2.35. The compositions have high solids contents relative to prior art compositions, and at least about 70% of the theoretically available calcium ions remain dispersed in the compositions at ambient temperatures. The compositions are in the form of a colloidal suspension having very little or no sedimentation. Finally, the compositions can be mixed with food products (e.g., cow's milk, soy milk) to substantially increase the calcium available in the product without negatively affecting the taste, color, or smell of the product.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to provisional application No. 62/299,367, filed Feb. 24, 2016, the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to hooks for hanging tools. More precisely, the present invention is directed to improvements to a tool mounted multi-position carrying hook. BACKGROUND OF THE INVENTION [0003] Tool hooks are typically used to carry a portable tool or like implements around a job site to leave the user's hands free to do other things such as climb a ladder, support or align construction components, operate other tools, or perform other tasks. One type of hook is separate from the tool device and attached to a user's belt or other user location while the tool is placed and replaced on the hook. Another type of hook is attached as part of the tool—the hook and associated tool are placed and replaced together on the user's belt or other user location. An example of the first type is a hook that is normally affixed to a tool belt upon which a tool is selectively placed. A common example of the second type is a tape measure with integrated hook. SUMMARY OF THE INVENTION [0004] The present invention in a preferred embodiment includes a hook that is normally attached to a portable or hand held tool or other device that is to be carried by a user. The hook is movable on the tool between different positions whereby the hook is usable at or from selectable locations of the tool. The hook may also include a stowed position in which it is not normally accessible for use. For example, the hook may selectively extend from a left and right side of a tool, or only one side, to accommodate different handed users. The hook may further be stowed out of the way to extend from neither side. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIG. 1 is a left side elevational view of a tool incorporating a deployable belt hook, with the hook stowed. [0006] FIG. 1A a rear elevational view of the tool of FIG. 1 [0007] FIG. 2 is the tool of FIG. 1 with the hook deployed on a left side of the tool. [0008] FIG. 2A is a rear elevational view of the tool of FIG. 2 [0009] FIG. 3 is the tool of FIG. 1 with the hook, not visible, deployed on the right side of the tool. [0010] FIG. 3A is a rear elevational view of the tool of FIG. 3 . [0011] FIG. 4 is a left rear perspective detail view of the tool showing the hook in the stowed position. [0012] FIG. 5 is the tool of FIG. 4 with the hook in an intermediate position between deployed and stowed. [0013] FIG. 6 is the tool of FIG. 4 with the hook deployed on the left side of the tool. [0014] FIG. 7 is a right front perspective detail view of a rear of the tool of FIG. 4 with the hook deployed on the right side of the tool. [0015] FIG. 8 is a partial cross-sectional view of the tool of FIG. 4 showing hook support and securing elements. [0016] FIG. 9 is a left rear perspective view of a subassembly of a hook and support elements. [0017] FIG. 10 is a left front perspective view of the subassembly of FIG. 9 . [0018] FIG. 11 is a rear perspective view of a hook subassembly release button. [0019] FIG. 12 is a rear perspective view of a hook support structure. [0020] FIG. 13 is a rear perspective view of a belt hook. [0021] FIG. 14 is a front perspective view of the subassembly of FIG. 10 , viewed from a more front position. [0022] FIG. 14A is the cross-sectional view indicated in FIG. 14 in a pre-assembly condition. [0023] FIG. 14B is the view of FIG. 14A in an assembled condition. [0024] FIG. 15A is a cross-sectional view of the subassembly of FIG. 14 , with the belt hook not shown and with a release button extended. [0025] FIG. 15B is the view of FIG. 15A with the release button pressed. [0026] FIG. 16 is the view of FIG. 9 with a section line indicated. [0027] FIG. 17 is the perspective, partial cross-sectional view indicated in FIG. 16 . [0028] FIG. 18 is a left, front perspective view of a tool housing showing a subassembly mounting. [0029] FIG. 19 is a top left side perspective view of a tool with an alternative embodiment deployable belt hook, with the hook stowed. [0030] FIG. 20 is the tool of FIG. 19 with the hook deployed. [0031] FIG. 21 is a top view of the tool of FIG. 20 . [0032] FIG. 22 is a right side elevational view of the tool of FIG. 19 with a cut-away exposing hook elements. [0033] FIG. 22A is a transverse cross-sectional view at a hook mounting of the tool of FIG. 22 . [0034] FIG. 22B is a longitudinal cross-sectional view of the tool of FIG. 22 with the hook stowed. [0035] FIG. 22C is the view of FIG. 22B with the hook deployed. [0036] FIG. 23 is a perspective view of a belt hook component of FIGS. 19-22 . [0037] FIG. 24 is an alternative embodiment double hook. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0038] FIGS. 1 to 3 show a preferred first embodiment of a hook assembly fitted to a rear of a staple gun type device. As illustrated, the staple gun is a “forward action” type with a pressing area of handle 12 being above the front area of body 10 where the staples are ejected (i.e., left side of the three side elevation views). A length of the body extends from the front to a rear. A selectively deployable belt hook subassembly is preferably fitted near or at a rear of grip opening 17 within cavity or opening 15 of body 10 . Body 10 includes an upper grip area 13 above the grip opening and a lower body portion 14 under grip opening 17 . Handle 12 forms an upper region of a grip portion of the tool. Preferably as shown, the hook subassembly is positioned lower and rearward on body 10 to clear the grip area of upper grip 13 and handle 12 . In this manner, the hook features do not interfere with gripping, carrying and using the tool while also keeping the hook supported tool balanced in a convenient position for grasping and use. [0039] The hook subassembly includes rotatable hook support structure 20 , release button member 40 and elongated hook 30 . These elements are shown in most of the drawing figures. In FIG. 1 , hook 30 is stowed between sidewalls of body 10 , shown hidden in FIG. 1A . The hook subassembly preferably fits entirely, or nearly so, within confines of body 10 in the stowed condition. Therefore, the provision of the hook feature does not need to add any obstructions or bulk to the size of the tool with which it is used. In this position, the hook is fully out of the way to allow normal use of the staple gun or other tool. The movable hook structure is substantially confined within body 10 of the tool while body 10 , or the tool overall including the hook, need not be enlarged to fit this structure or related attachments thereof although it may be so enlarged. In particular the stowed hook is confined between two sides of the body as well as preferably between a top and a bottom of the body or related structure. In FIG. 1 hook 30 is vertically aligned with hook 20 , being below the support as illustrated. For example, a user who does not wish to use a belt hook will not suffer any compromise in the tool's function or bulk by its inclusion with the tool. As described here the bulk of the tool is an external overall size or envelope of the device wherein the stowed hook fits substantially entirely within the envelope of the tool. This contrasts with typical prior tool mounted hooks which necessarily protrude, or include mountings that add bulk, to an associated tool. Other implements to be carried, for example, hand and power tools and small household appliances, may be used in association with the present invention deployable hook. [0040] Hook support 20 includes a longitudinal axis by which it is pivotally mounted to body 10 . Button 40 includes round perimeter 43 , FIG. 9 . Hook support 20 includes boss 23 extending into housing recess 19 , FIG. 8 , hidden lines in FIG. 18 . Together sides 43 and boss 23 form a pivot axis about which the hook subassembly pivots. Alternatively, perimeter 43 may be part of hook support 20 , for example, with button coaxially fitted within a surrounding structure of hook support 20 . Further, body 10 may include bosses that fit to recesses of the hook subassembly to provide the pivot axis. Other suitable mountings are contemplated. [0041] In FIG. 2 , the hook extends or protrudes out of the page from a left side of the tool and to the left of hook support 20 , FIG. 2A . More broadly the hook is to a side of the hook support. This configuration will be convenient for a right-handed user, or where the work is to the right of a user. In this configuration when using the right hand the tool may be lifted in its usable position from a tool belt or equivalent item on the user. In this manner, the hand is placed atop handle 12 with the index finger extending through grip opening 17 at the front of the opening. In FIGS. 3 and 3A the hook extends from a right side of the tool as well suited for a left-handed user or a work object, implement, or tool that is to the left of a user where the left hand may be most convenient. The deployed hook extends substantially parallel to an exterior face of the body to form a “belt capture slot” whereby it normally captures a tool belt or similar item outside of and against the tool body. [0042] In the preferred embodiment shown, the hook subassembly rotates about 180° between usable positions or stops, in about 90° increments. The hook may rotate other than 180°, for example, a full circle or less, if desired. This may require opening cavity 15 to be larger, extending farther above hook support 20 , for example. As shown, opening cavity 15 extends downward whereby the hook stowed position has hook 30 located under hook support 20 . The hook subassembly may further be rotated by increments other than about 90°, for example about 45° or other positions to fit the contours of a particular tool to which it is attached. In various embodiments, the hook subassembly rotation may be loose or free, friction damped, include hard stops, reversibly locked in place, or any combination thereof, as described in more detail below. [0043] Button 40 is slidably fitted to hook support 20 ; see FIGS. 8, 15A and 15B . FIGS. 11 and 12 show these separate parts. Spring 50 or equivalent element biases button 40 out of recess 22 . Flanges 41 of button 40 terminate outwardly at shoulders 42 . Slot or slots 21 receive flanges 41 . Button 40 therefore can move axially in and out of recess 22 , between a disengaged and an engaged position respectively. Button 40 is substantially fixed in rotation within or upon hook support 20 , with an allowance for some looseness as a result of normal mechanical tolerance. In the normal outward position of FIGS. 8 and 15A , shoulders 42 engage notches or equivalent ribs 18 of housing 10 . In FIG. 8 , horizontal notches 18 are engaged by shoulders 42 . In the deployed left or right hook positions, FIGS. 2 and 3 , vertical notches 18 a, FIG. 18 , are engaged by shoulders 42 . Other relative relations between notches 18 , 18 a and shoulders 42 are contemplated. For example, slots 21 may be positioned about 90° or other angle to the vertical orientation shown in the view of FIG. 12 . With shoulders 42 engaged to notches 18 or 18 a, the hook subassembly is in a fixed or set position, held securely from rotating within cavity 15 or other equivalent location. If spring 50 is stiff enough then the stops may be less determinate or at the limit there are no stops or notches 18 at all whereby hook support 20 rotates against a simple friction engagement for example pressing shoulders 42 against a relatively smooth surface of body 10 . Alternatively, spring 50 may be softer or, along with button 40 , not present at all whereby hook support 20 rotates freely. [0044] Button 40 is exposed and accessible for use on a rear of the tool body as shown. To change the position of the hook, button 40 is pressed inward against the bias of spring 50 to the retracted button position shown in FIGS. 5 and 15B . Button 40 and the hook support structure are then in a released position. Recess 13 surrounding button 40 allows for full pressing of the button while holding the button generally flush with a surrounding housing surface or body envelope in the normal extended position of the button. In this way, the button will not protrude from the tool and can not be easily be pressed accidentally. [0045] With the button pressed, shoulders 42 are now flush with a rear 26 of hook support 20 , FIG. 15B . As seen in FIG. 8 , dashed lines, button 40 moves to the position 40 a while shoulder 42 moves to 42 a. This condition retracts the shoulders from notches 18 , see also FIG. 18 . In FIG. 5 , the hook subassembly is in an intermediate position between the three preferred positions of stowed and deployed. When the hook is moved to one of these preferably three determinate positions, button 40 automatically pops out into notches 18 or 18 a under the bias of spring 50 to hold and operationally fix the selected position of the hook support to the body. No further user action is required to fix the selected position. More or fewer determinate positions or stops may be provided by having more or fewer notches or other equivalent structures. [0046] Preferably, there are redundant features to hold rotational positions of the respective parts. For example, the exemplary embodiment has two slots 21 in hook support 20 with corresponding two flanges 41 of the button structure. Further, there are a pair of respective body notches 18 and 18 a to engage the pair of button shoulders 42 . With more than one rotational fixing feature, the hook is securely held in a selected position. More or fewer than two of each feature or equivalent may be used. The hook is rotationally fixed within movable limits determined by part tolerance and function. [0047] Hook support 20 may be a molded part with hollow front interior 24 ( FIG. 10 ) and a back for the rear features ( FIG. 12 ). This helps keep the structure light weight to minimize its effect on use of the associated tool. Along with recess 22 for button 40 , there is an optional ramp 27 . As seen in FIGS. 14A and 14B , ramp 27 allows for a snap fit of hook 30 into hook support 20 . Hook 30 is a preferably wire-formed structure while it may also be formed from sheet metal, plastic, fiberglass, or other material. The hook includes U returns 34 and internal legs 35 . Preferably single leg 37 , FIGS. 10 and 13 for example, is the operative element to form the tool belt capture slot. Bent ends 31 hold the hook within hook support 20 as seen in FIGS. 14 and 14B . See also FIG. 9 for the positions of these hook elements within hook support 20 . To assemble the hook to the hook support, legs 35 are pressed inward along ramps 27 , FIG. 14A . The legs deflect inward, 31 a and 35 a, until bent ends 31 have slid to catches 27 a, FIG. 14B . The legs then snap into position where bent ends 31 are locked behind catches 27 . Elongated recess 28 holds and stabilizes legs 35 against normal forces of use that would move the legs laterally within hook support 20 while catches 27 hold the hook from pulling rearward out of the hook support. The preferred embodiment snap fitted design is compact, low weight, and low cost. Angled end 33 of the hook guides the hook to behind a belt, waist band or other item of attire. [0048] As shown, the hook has a single operative leg 37 with the single leg extending along an outside of hook support 20 . The hook leg is able to move within and beyond an envelope of the body. As described herein, the envelope of the body is the shape, size or bulk of the body absent any protruding structure of a belt hook. The preferably single leg may include the two joined wire elements illustrated or the sheet metal structure described above. [0049] As shown, opening cavity 15 is fully surrounded within body 10 . In alternative embodiments, the hook subassembly may be fitted into a recess of the body, for example, open at a rear of the tool (not shown). Further, the hook may be mounted substantially externally to the tool, for example, upon ribs extending from the body (not shown) so that the hook subassembly is more exposed on the body. [0050] FIGS. 19 to 22 show a tool using an alternative embodiment deployable tool belt hook. Handle 112 is pivoted near a front of body 110 , left side in FIG. 19 . Grip opening 117 extends from a central area toward a rear of the body. In the illustrated staple gun type fastening device the main operational components, not shown, are in front of grip opening 117 . The hook structure shown may be applicable when there is more limited space available for the hook feature compared for example to the structure of the tool of FIGS. 1 to 18 . Hook 130 is preferably a wire form or equivalent structure. [0051] As seen hook 130 fits within narrow cavity or slot 115 without obstructing grip opening 117 . Slot 115 is about a same height as a diameter of the wire of hook 130 , being less than two times such a diameter. Fastener track 180 is immediately below slot 115 so that slot 115 fits in a small space between track 180 and grip opening 117 . Similar to cavity 15 of FIGS. 1 to 18 , the slot forming cavity 115 is located adjacent to and at a rear of the grip opening. In FIGS. 19 and 22B the hook is stowed. The hook including rear loop 132 is within confines of body 110 whereby the stowed hook does not add to a bulk of the tool. In the other assembly drawing figures, the hook is deployed in an operative position and available for use. The hook is widest at loop 132 and narrowest at clip area 131 . Loop 132 , inner leg 136 and outer leg 137 are all substantially co-planar whereby the wire form of hook 130 fits into narrow cavity slot 115 . In this manner, the plane of the hook defined by the loop and legs is substantially perpendicular to a horizontal plane of the tool as defined by the page of FIGS. 22B and 22C . When deployed leg 137 forms a belt capture slot between body 110 and leg 137 , FIG. 22C . [0052] In FIG. 22 hook pivot 135 is seen. The hook pivots about hinge area 113 of body 110 with a hook pivot axis described by pivot 135 being vertical, see also FIG. 22A . As shown, hinge area 113 includes a member from both halves of the housing body 110 which meet at pivot 135 to rotatably confine the hook. In the stowed position, inner leg 136 abuts rib 111 , or other limit stop structure, FIG. 22B . Inner leg 136 is between loop 132 and pivot 135 . [0053] Access opening 118 , FIGS. 19 and 20 , provides finger access to pull on loop 132 to allow outward deployment of the hook. Resilient detent bumper 120 includes exemplary ridge 121 to hold the hook stable in either the deployed or stowed position. Optionally, the bumper or equivalent structure may be relatively rigid while deflection of the hook wire provides the detent action. With the hook deployed and stable the tool can be clipped or held on a tool belt or equivalent item a user is wearing. The hook remains available for use in this configuration. If the hook is no longer needed it can be easily moved out of the way to the stowed position. [0054] Optionally, the hook of FIGS. 19 to 22 may be held in a position by a secondary structure such as a thumb screw, lever or similar, not shown. In particular, in the deployed position the hook then cannot be unintentionally pushed back in from its operative position. [0055] As shown hook 130 deploys from a single side of the tool. Optionally, the hook could extend both directions for example by rotating about its long axis, not shown, and pivoting out the right housing side. Further there may be two hooks stacked, not shown, that fit in a partially wider slot 115 and operate in opposed directions. Hook 130 may include a structure with two vertically spaced parallel hooks, FIG. 24 . Such a double hook pivots about the same pivot 135 . This taller structure may be suited when there is enough free space in the tool body to fit. Slot cavity 115 then has two spaced parallel slots or a wider single slot. [0056] While the particular forms of the invention have been illustrated and described, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. It is contemplated that elements from one embodiment may be combined or substituted with elements from another embodiment.

An improved tool belt hook is selectively deployable on a portable tool or device. The hook structure is deployable in selected directions or positions on the tool. A stowed position is also preferably included wherein the hook structure is substantially contained within confines of the tool body to be out of a user's way. A closely integrated pushbutton release may allow the hook to rotate between selected operative positions and automatically engage to such position. The button is easily operated while effectively remaining within confines of the tool body. The tool hook assembly is compact and low cost.

TECHNICAL FIELD [0001] This invention relates to fastener products such as those having an array of projections arranged to resist shear displacement across the surface of the fastener product. BACKGROUNDS [0002] Some fasteners, for example, hook and loop fasteners, include fastener components with engageable elements constructed to engage elements of corresponding fastener components. In the case of self-engaging fasteners, the fastener elements of the two fastener components are similar or the same, and the two fastener components may be regions of a single sheet. [0003] There is a need in certain applications for fasteners that, when engaged, provide high shear strength properties in a desired direction. Some applications also require low cost fasteners offering good resistance to disengagement and in-place adjustability. [0004] There is also a need to be able to consistently and efficiently produce fastener components having differing functional characteristics, using techniques that require limited changeover in basic tooling, yet allow for adjustments to produce the desired fastener characteristics. SUMMARY [0005] According to one aspect of the invention, a self-engageable fastener component includes a sheet-form base, and an array of wedge-shaped, engageable elements extending integrally from at least one side of the sheet-form base. The engageable elements each have an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented in a common direction. [0006] In some embodiments, the engageable elements are arranged in at least one row along the sheet-form base, the row extending toward the single edge. For some applications, the elements are arranged in an array of multiple rows and columns. In preferred embodiments, the elements are arranged in multiple rows, with elements of adjacent rows offset from one another along their respective rows. The elements of adjacent rows are offset, for example, by about one-half a nominal spacing between adjacent elements within a row. [0007] In some implementations, the curve defined by the upper edge in top view is substantially circular with a constant radius of curvature. In preferred implementations, the constant radius of curvature is from about 0.25 to 2.5 centimeters. [0008] For some applications, the curve defined by the upper edge in top view is not circular, but is, for example, parabolic, ellipsoidal, hyperbolic, or a mixture of such curves. [0009] In preferred embodiments, a maximum elevation of the upper edge above the top surface of the sheet-form base is between about 0.025 and 6.3 millimeters, each engageable element has a width, measured along the sheet-form base perpendicular to said single edge, of between about 0.13 and 6.3 millimeters, each engageable element has a length, measured along the sheet-form base parallel to the edge, of between about 0.13 and 2.54 centimeters, and the non-engageable side of each fastener element rises from the sheet-form base at an angle of between about 5 and 45 degrees. [0010] In some instances, the engageable sides of the wedge-shaped elements overhang the sheet-form base, and the engageable side of each fastener element extends downward from the upper edge toward the sheet-form base at an undercut angle, measured in a midplane bisecting the fastener element and perpendicular to the sheet-form base, of between about 10 and 45 degrees. [0011] For some applications, the engageable elements extend outwardly from two opposite sides of the sheet-form base. In some instances, there are hook-shaped projections, and/or engageable loops proximate the wedge-shaped elements. [0012] In some implementations, the sheet-form base forms a tube, with the wedge-shaped elements extending from a curved surface of the tube. The curved surface can include an outer, or an inner surface of the tube. For some applications, the tube defines a longitudinal gap extending along its length between opposite edges of the sheet-form base. In some cases, the sheet-form base forms an elongated, U-shaped structure, and the wedge-shaped elements extend from an inside surface of the U-shaped structure, a majority of the engageable sides of the wedge-shaped elements directed away from an open edge of the U-shaped structure. In certain application, the wedge-shaped elements extend from an outside surface of the U-shaped structure. [0013] In some embodiments, the sheet-form base forms an elongated strap. In certain instances, the elongated strap includes only a single row of said wedge-shaped elements, all arranged with their engageable sides directed toward an end of the strap. For some applications, an aperture is defined adjacent one end of the strap, and the aperture sized to receive an opposite end of the strap therethrough. In preferred embodiments, the elongated strap includes an exposed retention edge along one side of the aperture, the retention edge is positioned to engage the engageable sides of the wedge-shaped elements with the opposite end of the strap pulled through the aperture, to resist removal of the strap from the aperture. [0014] For some applications, it is advantageous when the sheet-form base is secured to, and overlays a layer of resilient material, and the sheet-form base is flexible. [0015] In preferred embodiments, two fastener components, each as described above, are arranged with the engageable sides of their wedge-shaped elements overlapping one another to resist shear motion between the fastener components. [0016] According to another aspect of the invention, a method of making a fastener component includes providing a molding tool defining an array of cavities extending inwardly from an outer surface thereof. The moldable resin is transferred onto the outer surface of the molding tool, and the resin is pressed into the cavities of the molding tool, thus forming the engageable elements, while forming a base of resin on the surface of the molding tool, the base interconnecting the engageable elements. The cavities form engageable elements that are wedge-shaped, each wedge-shaped element including an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented toward a single edge of the sheet-form base. [0017] For some applications, the molding tool includes, for example, a rotatable mold roll positioned adjacent a counter-rotating pressure roll to define a pressure nip in which the moldable resin is pressed into the cavities to form the engageable elements. In some implementations, a sheet material is introduced into the nip with the moldable resin, and laminating the moldable resin to the sheet material under pressure in the nip. The sheet material can include, for example, a scrim material. [0018] In certain embodiments, the planar sheet material is formed into a tube, the engageable sides of a majority of the engageable elements being directed away from a common, open end of the tube. [0019] For some applications, the fastener component is in strap form, the method includes forming an aperture at one end of the fastener component, the aperture being sized to receive an opposite end of the fastener component. The fastener component includes an exposed retention edge along one side of the aperture, the retention edge being positioned to engage the engageable sides of the wedge-shaped elements with the opposite end of the strap pulled through the aperture, resisting removal of the strap from the aperture. [0020] According to another aspect of the invention, a seat bun includes a compliant material with a surface having a central region bounded on two opposite sides by elongated trenches, and a fastener component that includes a sheet-form base, and an array of wedge-shaped, engageable elements extending integrally from at least one side of the sheet-form base disposed within each trench. The engageable elements each have an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented in a common direction. The elements are arranged with the non-engageable sides of its wedge-shaped elements directed out of the trench. For some applications, the fastener components include elongated, U-shaped structures extending along each trench. In some instances, the fastener components comprise tubular structures embedded within each trench. [0021] The term “curve” as used herein is intended to include generally curved outlines that may encompass minor discontinuities or straight segments. [0022] The fastener components and fasteners disclosed herein can be particularly useful in applications requiring high shear strength. In addition to providing high shear strength, many of the fastener components and systems disclosed herein provide for ready disengagement and in-place fastener adjustability. Many embodiments can be molded in flexible form, with very low profile wedges, such that engaged sets of the fasteners occupy very little width between mating surfaces. The wedges can be arranged to allow engaged surfaces to be readily shifted for adjustment along rows of wedges, such as for adjusting the position of a picture frame fastened to a wall surface with such fasteners, for example, with the curved edges of the wedges of each row defining a series of detents for maintaining final engagement once shear load is reestablished between the wedges. The curvature of the edges helps to assist with adjustment of two mating arrays of wedges by allowing the apexes of the wedges to slide across one another without completely separating the mating fastener components, with the wedges overlapping. [0023] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will be apparent from the description and drawings and from the claims. DESCRIPTION OF DRAWINGS [0024] FIG. 1 is a perspective view of a fastener component according to one embodiment. [0025] FIG. 1A is an enlarged top view of a portion of the fastener component shown in FIG. 1 . [0026] FIG. 1B is an enlarged side view of a portion of the fastener component shown in FIG. 1 . [0027] FIG. 1C is a perspective view of a fastener component according to an alternative embodiment. [0028] FIG. 1D is a top view of the fastener component of FIG. 1C . [0029] FIG. 2 is a top view of the fastener component shown in FIG. 1 . [0030] FIG. 2A is a cross-sectional view of the fastener component shown in FIG. 2 , taken along line 2 A- 2 A in FIG. 2 . [0031] FIG. 2B is an enlarged view of a portion of the fastener component shown in FIG. 2A . [0032] FIG. 3 is a top view of the fastener component shown in FIG. 2 , the fastener component oriented such that it is engaging a like fastener component, creating a fastener according to one embodiment. [0033] FIG. 3A is a cross-sectional view of the fastener shown in FIG. 3 , taken along 3 A- 3 A. [0034] FIGS. 3B-3C are top views of a portion of the fastener system illustrated in FIG. 3 . [0035] FIG. 4 is a diagrammatic view of a process for making the fastener component shown in FIG. 1 . [0036] FIG. 4A is a diagrammatic view of a process for making a fastener component shown in FIG. 4B or 4 C. [0037] FIG. 4B is a laminated fastener component made by the process shown in FIG. 4A . [0038] FIG. 4C is a fastener component made by the process shown in FIG. 4A using a scrim web material. [0039] FIG. 4D is a diagrammatic view of a process for making a fastener component with engageable elements on both sides of a sheet-form base. [0040] FIG. 5 is a diagrammatic view of an alternative process for making the fastener component shown in FIG. 1 . [0041] FIG. 6 is a diagrammatic top view of a portion of flat tooling. [0042] FIG. 7 is a cross-sectional view of a tool roll being cut. [0043] FIG. 7A is a side view of a dovetail cutter. [0044] FIG. 7B is an end view of a dovetail cutter. [0045] FIGS. 8-9 are perspective views illustrating formation of a tubular fastener component with engaging elements on the inside. [0046] FIG. 9A is a cross-sectional view of the fastener component shown in FIG. 9 (after joining), taken along line 9 A- 9 A in FIG. 9 . [0047] FIGS. 10-11 are perspective views illustrating formation of a tubular fastener component with engaging elements on the outside. [0048] FIG. 11A is a cross-sectional view of the fastener component shown in FIG. 11 , taken along line 11 A- 11 A in FIG. 11 . [0049] FIG. 12 is a perspective view of a tubular fastener system employing the tubular fastener components shown in FIGS. 9 and 11 . [0050] FIG. 13 is a perspective view of the tubular fastener component shown in FIG. 9A in a plastic body. [0051] FIG. 13A is a side view of a fastener component according to an embodiment. [0052] FIG. 13B is a side view of a fastener component according to another embodiment. [0053] FIG. 13C is a cross-sectional view of a fastener system employing the fastener components of FIGS. 13A and 13B . [0054] FIG. 14 is a perspective view of a mold insert illustrating the tubular fastener component of FIG. 9 (after joining) on a protrusion. [0055] FIG. 14A is a cross-sectional view of a tubular fastener component on a mold protrusion, a portion of the mold protrusion having a diameter larger than the nominal diameter of the fastener component, and the tubular fastener component including a region without engageable elements. [0056] FIG. 14B is a cross-sectional view of a tubular fastener component on a mold protrusion, the fastener component including a seal about an inner surface of the tubular structure. [0057] FIG. 14C is a cross-sectional view of a portion of a tubular fastener component showing overlapped edges that are tapered in thickness. [0058] FIGS. 15-16 are perspective views of alternative fastener components employing the fastener component shown in FIG. 1 . [0059] FIG. 17 is a side view of a fastener component according to an embodiment. [0060] FIG. 18 is a side view of a fastener system according to an embodiment. [0061] FIG. 19 is a perspective view of a fastening system according to an embodiment. [0062] FIG. 20 is a perspective view of a fastener component according to an embodiment. [0063] FIG. 20A is a perspective view of a fastening system according to an embodiment formed from the component of FIG. 20 . [0064] FIG. 21 is an alternative fastening system. [0065] FIG. 22 is a fastener product. [0066] FIG. 23 is a partial cross-sectional view of a fastener product having a releasably retaining arm in a fastened position. [0067] FIG. 24 is a perspective view of a molding nip for producing the fastener product of FIG. 26 . [0068] FIG. 25 shows area 25 of FIG. 24 . [0069] FIG. 26 is a perspective view of a fastener product sheet, and a product that has been separated from the sheet. [0070] FIG. 27 is a plan view of the fastener product of FIG. 26 . [0071] FIG. 28 is a cross-sectional view of a compliant material sandwiched between a tubular structure, and a base that includes engageable elements. DETAILED DESCRIPTION [0072] Referring to FIG. 1 , flexible fastener component 10 includes an array of arcuate engageable elements 12 integrally molded with and extending outwardly from one side of a solid sheet-form base 14 . The engageable elements 12 are arranged in scalloped rows R, and are preferably staggered, as shown. The engageable elements 12 each include an engageable side 18 and a non-engageable side 20 disposed opposite the engageable side. Preferably, the elements are substantially identical to each other, as shown. [0073] The engageable elements 12 may be formed by a process having a machine direction (MD) and a cross-machine direction (CD), in which case the engageable elements 12 may be arranged with rows R extending in the machine direction so that engageable sides 18 face uni-directionally in the cross-machine direction. Each engageable side 18 is defined by an upper edge 17 and by a lower edge 19 where the engageable element intersects the sheet-form base 14 . Both upper and lower edges 17 , 19 define curves, for example, a circular curve as shown in FIG. 1 , in the direction of the rows, for example, the machine direction. A circular curve is a curve that would sweep out a circle if it continued. Because the elements 12 are staggered, the apexes A 1 , A 2 of the arcuate engageable elements 12 in adjacent rows are offset from each other. [0074] In some embodiments, fastener component 10 is made of thermoplastic material. Suitable thermoplastic materials include polyethylenes, polypropylenes, polyamides, PVC, and polyesters. In other embodiments, especially when high chemical resistance and/or high temperature stability is required, fastener component 10 is made of a thermoset material. Suitable thermoset materials include natural rubbers, synthetic rubbers and rigid or flexible polyurethanes. [0075] In some embodiments, the upper and/or lower edge(s) 17 , 19 may define a circular curve with a constant radius of curvature. To illustrate this point, the radius of curvature of lower edge 19 shown in FIG. 1 is r 19 , while the radius of curvature of upper edge 17 is r 17 . The radius of curvature may be, for example, from about 0.1 inch to about 1 inch (0.25 cm-2.5 cm). In other embodiments, the upper and lower edges 17 , 19 may define a curve that is non-circular and, therefore, has a changing radius of curvature. Examples may include curves that are parabolic ellipsoidal or hyperbolic in shape. FIGS. 1C-1D illustrate a fastener component 11 with parabolic upper and lower edges 17 ′, 19 ′. [0076] In some embodiments, the maximum height H ( FIG. 1 ) of the engageable elements 12 above the sheet-form base 14 at the apexes A 1 , A 2 is, for example, from about 0.001 inch to about 0.250 inch (0.0025 cm-0.64 cm). In other embodiments, where the engageable elements resemble “fish scales,” the height H is, for example, from about 0.001 inch to about 0.050 inch (0.0025 cm-0.13 cm). “Fish scale” engageable elements are useful, for example, when maximum flexibility is desired or when the application requires a low degree of skin irritability, for example, when the fastener component is fixed to a garment of clothing. [0077] In some embodiments, a maximum length L of the engageable elements 12 in the direction of the rows is, for example, from about 0.05 inch to about 1.0 inch (0.13 cm-2.5 cm), while the maximum width W in the engaging direction along the sheet-form base is, for example, from about 0.005 inch to about 0.25 inch (0.013 cm-0.64 cm). In some embodiments, the spacing S between rows in the engaging direction, measured along the sheet-form base from an end of a row to the beginning of an adjacent row is, for example, from about 0.005 inch to about 0.25 inch (0.13 cm-0.64 cm). [0078] Referring to FIGS. 2-2B , each engageable element 12 defines angles α and β with respect to sheet-form base 14 . Referring now particularly to FIG. 2A , angle α is the angle formed between the top surface of the sheet-form base and the top surface of the engageable element. Referring to FIGS. 2 and 2 B, lower edge 19 is not directly below upper edge 17 , but is offset, the offset defining an undercut angle β. Referring particularly to FIG. 2B , angle β is the angle formed between a line L 1 connecting upper edge 17 to lower edge 19 in a plane P E in the engaging direction ( FIG. 1 ) that is perpendicular to the sheet-form base, and a line L 2 in the same plane that connects upper edge 17 to the sheet-form base. In some embodiments, angle α is, for example, from about 5° to about 45°, while angle β is, for example, from about 10° to about 45°. The presently preferred embodiment has an α angle to 30° and a β equal to 15°. [0079] Fastener components having engageable elements like those shown in FIG. 1 are useful for engaging, for example, similar fastener components, forming a high shear strength fastener system. Applications and methods of forming the components will be discussed further below. [0080] Referring to FIGS. 3-3C , a high shear fastener 30 includes two flexible fastener components 10 , oriented such that the engageable elements 12 of the top fastener component 32 face the engageable elements 12 of the corresponding bottom fastener component 34 . The top fastener component 32 is further oriented so that the engageable sides 18 of elements 12 point from left to right. Bottom fastener component 34 is oriented such that engageable elements 12 extend upwardly to mate with the engageable elements 12 of the top fastener component 32 . The bottom fastener component 34 is further oriented so that the engageable side 18 of elements 12 point from right to left. Now, referring particularly to FIG. 3A , when the bottom fastener component 34 is fixed, and the top fastener component 32 is moved in a direction indicated by arrow 36 , a high shear engagement occurs as the engageable sides 18 of the fastener elements 12 of both components restrict movement in this direction. However, when the top fastener component 32 is moved in the opposite direction, indicated by arrow 38 , no engagement of the top fastener component 32 with the bottom fastener component 34 occurs and the two components slide relatively freely past each other, making a “clicking” sound as the engageable elements slide past each other. Referring back to FIG. 3 , top fastener component 32 and bottom fastener component 34 are also relatively free to slide past one another in the direction in which the rows of elements extent, i.e., the directions indicated by arrows 40 and 42 . Referring particularly to FIGS. 3B and 3C , which are top views of row R 1 engaged with row R 2 ( FIG. 3 ), when row R 1 is fixed and row R 2 is moved in a direction indicated by arrow 40 or 42 , there is slight resistance to movement, as engaging elements “rise up” from wells 44 ( FIG. 3B ) through the maximum of engageable side 18 and come to rest in adjacent wells 44 ( FIG. 3C ). This feature allows for in-place fastener adjustability. As an example to further illustrate adjustability, fastener component 10 may be, for example, attached to a wall in a room with the engageable side directed upwardly toward the ceiling of the room. Another fastener component 10 may be, for example, attached to the back of a shallow, heavy rectangular object, such as a picture frame with the engageable side directed downwardly. The heavy object may now be placed on the wall and held in place by the engageable elements. While still in-place on the wall, the heavy object may be translated laterally in units of length L along the wall, rising up against gravity from wells 44 and passing over each arcuate element before coming to rest in the adjacent wells as described above. Referring now to FIGS. 1 and 3 A, decreasing spacing S allows for finer adjustment steps. In the example above when the heavy object is a picture frame, decreasing spacing S allows for greater adjustability (smaller steps) along the height of a wall. Referring now again to FIGS. 2A-2B and FIG. 3 , increasing angle α makes it more difficult to slide components 32 and 34 past each other when oriented in the high shear mode discussed above. Increasing angle β allows for enhanced robustness in peel mode. While an angle β equal to 0° will work in shear mode, it will not provide much resistance in peel mode. In the example above where the heavy object is a picture frame, the robustness translates into how easy it is to accidentally cause the picture frame to fall off the wall by bumping the frame in a direction perpendicular to the wall to which it is attached. [0081] Referring now to FIG. 4 , a process for forming the fastener component 10 shown in FIG. 1 is illustrated. Thermoplastic resin 50 from extruder 52 is introduced into nip 54 formed between a supporting pressure roll 56 and a mold roll 58 . Pressure in the nip causes thermoplastic resin 50 to enter blind-ended forming cavities 60 of mold roll 58 while excess resin remains about the periphery of the mold roll and is calendared to form sheet-form base 14 . As the rolls 56 , 58 rotate in opposite directions (shown by arrows), the thermoplastic resin proceeds along the periphery of the mold roll until it is stripped by stripper roll 62 . The resulting fastener component 10 is described above. The direction of travel of the material illustrated in FIG. 4 is referred to as the “machine direction” (MD) of the material and defines the longitudinal direction of the resulting product 10 , while the cross-machine direction (CD) is perpendicular to the machine direction. Further details regarding processing are described in Fischer, U.S. Pat. No. 4,775,310, the disclosure of which is hereby incorporated in full by reference. [0082] In another embodiment, illustrated in FIG. 5 , an alternate technique for producing fastener component 10 of FIG. 1 is employed. The process is similar to that described above with reference to FIG. 4 , except only a mold roll 58 is used, i.e., no pressure roll 56 is necessary. Here, the extruder 52 is shaped to conform to the periphery of the mold roll and the extruded resin 50 is introduced directly to a gap 64 formed between the mold roll and the extruder 52 . From here, flexible fastener component 10 is stripped from the mold cavities 60 by stripper roll 62 as described above. Further details regarding this process are described by Akeno in U.S. Pat. Nos. 5,781,969 and 5,913,482, the disclosures of which are hereby incorporated in full by reference. [0083] Referring now to FIGS. 4A-4C , a process for forming fastener components bonded to a web material is illustrated. Web material 53 is brought into nip 54 formed between roll 58 and roll 56 as discussed above. Web material can be, for example, a relatively non-porous material such as a plastic sheet material or a relatively porous textile gauze material such as a scrim material. If the web material is relatively non-porous, fastener components like that of FIG. 4B result. If the web material is a relatively porous material, fastener components like that of FIG. 4C result, as the molten resin penetrates the pores of the scrim material. Depositing molten resin upon a scrim material is discussed in U.S. patent application Ser. No. 10/688,301, filed Oct. 15, 2003, the entire content of which is hereby incorporated by reference. [0084] Other processes for forming flexible fastener component 10 are possible. For example, the processes described by Jens, U.S. Pat. No. 6,432,339, the disclosure of which is hereby incorporated in full by reference. In yet another process, flexible fastener component 10 may be formed from sheets of a pre-form material that may be, for example, pre-heated and compression molded, the heat and the pressure forming the engageable elements 12 . The advantage of this type of processing may be, for example, the use of flat, inexpensive tooling and the use of a relatively inexpensive hydraulic press. Another advantage of the compression molding process is that it allows for the use of thermoset resins that offer, for example, higher temperature stability and better chemical resistance when compared to thermoplastic materials. The disadvantage of this type of processing may be, for example, relatively low throughput since it is a batch process instead of a continuous process. [0085] Referring to FIG. 4D , a process for forming fastener components with engageable elements on both sides of a sheet-form base is illustrated. Thermoplastic resin 50 from extruder 52 is introduced into nip 54 formed between two mold rolls 58 . Pressure in the nip causes thermoplastic resin 50 to enter blind-ended forming cavities 60 of mold rolls 58 , forming a double-sided fastener component. [0086] Referring now specifically to Box 4 , Box 4 A, Box 4 D and Box 5 of FIGS. 4, 4A , 4 D and 5 , respectively, additional post processing may be applied to fastener components. For example, Boxes 4 , 4 A, 4 D and 5 may represent “flat-topping” stations as described by Provost in U.S. Pat. No. 5,953,797, the disclosure of which is hereby incorporated in full by reference. Flat-topping can, for example, increase the peel strength of fastener systems by increasing the overhang of the engageable elements. [0087] Referring now to FIG. 6 , flat tooling can be machined to create, for example, a compression mold tool. The advantages of compression molding fastener components have been described above. Cavities 60 can be machined or burned (e.g., by EDM) into the tool. Other methods for forming cavities are known in the art. [0088] Referring to FIG. 7 , entire mold rolls 58 or large portions 76 thereof can be machined by holding mold roll 58 on table 70 and machining its surface, for example, with a CNC milling machine 72 to form cavities 60 . The milling machine may include, for example, a dovetail cutter 74 . In comparison to forming mold rolls from machined plates, this process has the advantage, for example, of fewer parts to assemble. In addition, this process can allow for, for example, less expensive tooling, faster tooling changeover, easier tool cleaning and may eliminate or reduce flashing. [0089] FIGS. 7A-7B show, a dovetail cutter 74 suitable for making the tooling described above. The geometry of cutter 74 can be described in terms of cutter diameter A, face width B, shank diameter C, overall length D and included angle φ. Suitable cutters may have, for example, the following dimensions: DIMENSION RANGE A 0.125 inch-3.000 inch (0.318 cm-7.62 cm) B 0.125 inch-2.000 inch (0.318 cm-5.08 cm) C 0.125 inch-1.500 inch (0.318 cm-3.81 cm) D 1.500 inch-4.000 inch (3.81 cm-10.16 cm) φ 30-60° [0090] Referring to FIGS. 8-9A , a tubular fastener component is made wrapping proximal end 80 and distal end 82 of fastener component 10 toward each other, as indicated by arrows 81 and 83 , until ends 80 and 82 physically touch or only a small gap 88 remains. Joining touching ends 80 and 82 can be accomplished by using, for example, an impulse sealer or an ultrasonic welder. In other embodiments, ends 80 and 82 may be joined by filling gap 88 with an elastomeric adhesive. This method can be particularly advantageous when a flexible joint is desired. A flexible joint may be desired, for example, when the tubular structure is placed on an oversized member (not shown), for example, an insert in a reactive injection mold or injection mold. Tubular fastener component 90 includes a first open end 84 and a second open end 86 . In another embodiment, the shape of the tubular fastener is fixed in the shape shown in FIG. 9 (i.e., gap is not closed) by heating the sheet-form base on the side opposite the engageable elements, and then holding in the shown configuration until the sheet-form base cools, thereby permanently setting the shape of FIG. 9 . This embodiment acts like a “spring” in that it the fastener component has radial flex which allows the fastener component to be placed onto over-sized objects, for example, protrusions in molds with a larger diameter than the fastener component. [0091] Referring to FIGS. 10-11A , tubular fastener component 100 may be formed by orienting flexible fastener component 10 so that the engageable elements 12 will extend on an outer surface of the finished tubular fastener component. The ends of fastener component 10 are then wrapped and joined as described above. [0092] Now referring to FIG. 12 , fastener system 110 includes tubular fastener component 90 and tubular fastener component 100 , sized such that the fastener component 100 fits inside of fastener component 90 . To more fully appreciate and understand the operation of the fastener system 110 , imagine fastener component 90 fixed in space, for example, extending from a molded part. Fastener component 100 is substantially free to move over fastener component 90 in a direction indicated by arrow 112 . However, when the fastener component 100 is moved in the opposite direction as indicated by arrow 114 , a high shear strength engagement results as the engageable sides 18 of engageable elements 12 of both tubular fastener components 90 and 100 restrict movement in this direction. [0093] Referring to FIG. 13 , a molded-in fastener component 120 is made by embedding tubular fastener compnent 90 in plastic 122 . This is done by placing tubular fastener compnent 90 on protrusion 132 of a mold insert 130 , for example, as shown in FIG. 14 , with engageable elements 12 adjacent the outer surface of protrusion 132 . Mold insert 130 may be a component, for example, of an injection mold or a reaction injection mold (not shown). The plastic 122 that embeds the tubular fastener compnent 90 may be, for example, a thermoplastic or a thermoset. In order to keep tubular fastener compnent 90 on protrusion 132 during cycling of the mold, it can be advantageous to fill the thermoplastic resin 50 ( FIG. 4 ) that will form fastener component 90 with a magnetic material. Further details about filling thermoplastic resin with magnetic materials, for example, a ferro-magnetic filler, are described by Pollard, U.S. Pat. No. 5,945,193, and Kenney, U.S. Pat. No. 6,129,970, the disclosures of which are hereby incorporated in full by reference herein. When tubular fastener components, such as component 90 of FIGS. 13 and 14 , are molded into a substrate, e.g., a foam bun, the height H of the engageable elements is generally minimized to avoid excessive longitudinal intrusion of material into inner portions of the tubular structure. To prevent intrusion, preferably, elements have a maximum height of less than 0.025 inch (0.635 mm), e.g., 0.010 inch (0.254 mm), or less, e.g., less than 0.005 inch (0.127 mm). [0094] Referring to FIG. 14A , and back again to FIG. 14 , in addition to minimizing the height of the engageable elements, another way to minimize intrusion of material longitudinally into inner portions of the tubular structure is to provide a mold protrusion 303 that includes a distal end portion 306 with a diameter larger than a nominal diameter the tubular structure 305 . The tubular structure 305 has an engageable element-free region 307 that seals against distal end portion 306 . The proximal end of protrusion 303 contains a tapered portion 309 for sealing the opposite end of tubular structure 305 . Distal end portion 306 of protrusion 303 includes a tapered lead-in 313 , and a tapered lead-off 311 to allow fastener component 305 to be easily placed onto, and removed from protrusion 303 . [0095] Referring to FIG. 14B , another way to minimize intrusion of material longitudinally into inner portions of a tubular structure is to provide a tubular fastener 320 that includes a resilient material, e.g., an elastomer, that forms a seal 321 at a distal end of the fastener component. The proximal end of the tubular structure 320 is sealed by tapered portion 324 on protrusion 322 , as discussed above. [0096] Radial intrusion of material into inner portions of a tubular structure can be minimized, for example, by longitudinally sealing the tubular structure with an elastomer, or by thermally fusing previously opposite edges. Referring to FIGS. 14C , another method of preventing radial intrusion of material includes overlapping opposite tapered edges 330 . Additional methods of preventing intrusion, and of attaching a fabric cover to a seat cushion, are discussed in “FASTENERS,” filed concurrently herewith, and assigned U.S. Ser. No. ______, the disclosure of which is hereby incorporated in full by reference, herein. [0097] Referring to FIGS. 13A-13C , a fastener component, for example, fastener component 10 of FIG. 1 , is fixed upon support 119 by, for example, using an adhesive, sewing or employing the process for forming fastener components bonded to web materials discussed above. Depending upon how the fastener component is oriented on support 119 , fastener components 121 and 123 of FIGS. 13A and 13B , respectively, can result. Fastener component 127 results from fixing fastener component 121 upon a support 125 , for example, by stitching. Similarly, fastener component 129 is formed by fixing component 123 onto a foam support 126 by, for example, using adhesive or integrally molding component 123 onto 126 . Pushing component 127 into component 129 creates a high shear fastening system. Support 125 may be, for example, a fabric cover and foam support 126 may be, for example, a foam bun that serves as a seat. Various methods of attaching a fabric cover to a seat cushion are described in Roberts, U.S. Pat. No. 5,964,017, Wildem et al., U.S. Pat. No. 5,605,373 and Angell, U.S. Pat. No. 5,499,859, the entire disclosure of each of which is hereby incorporated in full by reference. [0098] Referring to FIGS. 15-16 , another fastening system is illustrated for joining two sheet materials, for example, attaching an extruded plastic stud 140 to a sheet of metal 150 . Referring particularly to FIG. 16 , extruded stud 140 has a plastic male component 142 that is integral with and extends outwardly from one side. While only one male component 142 is shown, plastic stud 140 may have a plurality of such male components 142 . Male component 142 may be formed by extrusion during the same process as making plastic stud 140 or male component 142 may be, for example, adhesive bonded at a later time. Flexible fastener component 10 that is, for example, adhesive-backed is applied to both sides of the plastic male component 142 such that the engageable sides 18 of each of the engageable elements 12 point generally in an downwardly direction, creating male fastener assembly 144 . As an alternative process, male fastener assembly 144 may be, for example, molded as a single, unitary component. Referring particularly to FIG. 15 , sheet metal female assembly 148 includes an extruded plastic female member 146 attached to sheet metal 150 . While only one female member 146 is shown, sheet metal 150 may be attached to a plurality of such components. In addition, female member 146 may be formed, for example, by extrusion and can, therefore, be of considerable length. Flexible fastener component 10 that is, for example, adhesive-backed is applied to both sides of the plastic female member 146 such that the engageable side 18 of each of the engageable elements 12 point generally in an upwardly direction, creating female fastener component 148 . In an alternative embodiment, female fastener assembly 148 may be, for example, molded as a single, unitary component. Referring now to both FIGS. 15 and 16 , to attach extruded plastic stud 140 to sheet metal 150 , male assembly 144 is moved in direction indicated by arrow 152 while keeping female assembly 148 fixed in place. A high shear strength engagement occurs and high force needs to be applied in a direction indicated by arrow 154 to disassemble male assembly 144 from female assembly 148 . [0099] Referring next to FIGS. 17 and 18 , fastener component 139 includes engageable elements 140 similar to those of FIG. 1 , and hooks 142 , 144 extending outwardly from one side of a sheet-form base 146 . In the embodiment shown in FIG. 17 , hooks 142 , 144 extend toward and away from the viewer, respectively. In addition, loops 148 extend outwardly from the same side of the base 146 as the elements 140 . Elements 140 are positioned between hooks 142 , 144 and loops 148 . In some implementations, the elements 140 , 142 and 144 are molded at the same time using a modified version of the process described in FIG. 4 . In this modified process, the mold roll includes a combination of the tooling described above and the tooling described in Fischer, U.S. Pat. No. 4,775,310. Tooling described in Fischer is formed by a face-to-face assembly of thin, circular plates, of thickness, for example, between about 0.004 inch and 0.250 inch (0.010 cm-0.635 cm). Some of the plates, referred to as mold rings, have cutouts in their circular peripheries that define mold cavities while others, referred to as spacer rings, have smooth circular peripheries. The sides of the spacer rings serve to close the open sides of the cutout mold cavities and to serve to create the row spacing between rows of molded features. In some implementations, the loops 148 are bonded to base 146 by using, for example, adhesive. In other embodiments, loops are fed to the nip and melt incorporated. [0100] Referring now to FIG. 18 , a fastener system 149 that has good shear and peel performance may be formed by engaging two fastener components 139 . When a shear force F 1 is directed as shown in FIG. 18 , fastener system 149 exhibits good shear performance due to engageable elements 140 , as discussed above. In addition, when a peel force F2 is directed as shown in FIG. 18 , fastener system 149 exhibits good peel performance due to the engagement of hooks 142 , 144 with loops 148 . [0101] Referring to FIG. 19 , a container 150 includes a top 152 sized to fit onto a bottom 156 . Fixed upon an inside surface of top 152 are engageable elements 154 . Also, fixed upon an outside surface of bottom 156 are engageable elements 158 . The engageable elements 154 , 158 are similar to those shown in FIG. 1 . Engageable elements 154 are fixed upon top 152 such that the elements 154 are oriented with the engageable sides pointing up as shown. Engageable elements 158 are fixed upon bottom 156 such that the elements 158 are oriented with the engageable sides pointing down as shown. To apply or remove top 152 from bottom 156 , engageable elements 154 and vacant portions 157 are aligned, as are engageable elements 158 and vacant portions 155 . Twisting top 152 clockwise or counter clockwise allows top 152 to become “locked” onto bottom 156 as the rows of engageable elements engage one another. Engageable elements 154 , 158 may be fixed using adhesive, or injection molded during the formation of the part. [0102] Referring to FIG. 20 , fastener component 170 includes engageable elements 172 , 174 that extend from portions of sheet-form base 176 , the portions being disposed on opposite sides of base 176 . Fastener component 174 can be made by the process of FIG. 4D or elements 172 , 174 can be bonded to base 176 using an adhesive. Referring to FIG. 20A , elements 172 , 174 are oriented such that upon wrapping base 176 in the manner shown in FIG. 21 , a tubular structure 180 results that includes a dis-engageable, high shear fastener 181 . Fastener component 170 is useful for, for example, holding insulation to pipes. [0103] Referring to FIG. 21 , two pipes 192 , 198 , such as PVC pipes, can be joined by placing engageable elements 194 , 200 on pipes 192 , 198 . Pipe 192 includes a resilient material 196 bonded to a wall that can act as a fluidic seal. Pipe 192 is sized to accept pipe 198 and engageable elements are oriented such that pushing pipe 198 into pipe 192 creates a high shear engagement, similar to that described when discussing FIG. 12 . A fluid tight seal results upon further pushing pipe 198 into pipe 192 as pipe 198 engages and compresses resilient material 196 . In some embodiments, the resilient material is, for example, a thermoset such as a natural rubber. In other implementations, resilient material 196 is, for example, a thermoplastic elastomer such as elastomeric PVC. [0104] Referring to FIG. 22 , a fastener product 600 A includes an array of arcuate engageable elements 630 A integrally molded with, and extending outwardly from a base 615 A. The engageable elements each include an engageable side 633 A, and a non-engageable side 631 A. Both the upper 632 A and lower edges define curves (e.g., circular curves) such that the engageable side 633 A has a curved shape, as descrbed above in reference to FIGS. 1 , 1 A- 1 B, 2 A- 2 B. Similar fasteners are discussed in “FASTENER PRODUCTS,” filed concurrently herewith, and assigned U.S. Ser. No. ______, the disclosure of which is hereby incorporated in full by reference herein. [0105] Referring to FIGS. 22 and 23 , the head element 610 defines an aperture 645 . When the fastener strap 605 is inserted through the aperture 645 , the head element 610 cooperates with the fastener projections 630 A to prevent the strap 605 from retreating back through the aperture 645 . In other words, the head element 610 is configured such that it provides one-way movement through the aperture 645 . The head element 610 includes a retaining arm 658 that extends into the aperture 645 . When the strap 605 is pulled through the aperture 645 in the direction of the arrow, the first surfaces 631 A (non-engageable side) of the wedge-shaped fastener projections 630 A deflect the retaining arm 658 away from the projections 630 A allowing the strap 605 to proceed through the head element 610 . However, when the strap 605 is pulled in a direction opposite to that shown by the arrow, the second surface 633 A (engageable side) of the projection 630 A abuts and engages the retaining arm 658 . This prevents the strap 605 from exiting the head element 610 . The fastener product shown in FIG. 23 can be used to retain articles (e.g., tubes or pipes) in a bundle. Similarly, they can be used to suspend an article or articles from a beam or other structure. In addition, the fastener products can be useful as a human restraint mechanism (e.g., handcuffs). They can be wrapped around the wrists or ankles of a person and tightly fastened to restrain the person. [0106] Referring to FIG. 24 , an apparatus is shown that can be used to produce the fastener product shown in FIG. 22 . Mold roll 215 includes multiple lanes of molding cavities 252 arranged across its transverse direction. Each lane of molding cavities is circumferentially separated along the mold roll 215 such that the fastener product sheet molded, when molten resin is delivered to nip N by die 205 connected to an extruder, includes multiple, longitudinally separated lanes of fastener projections. In other embodiments, the mold roll can include a continuous array of molding cavities spanning the circumferential surface of the mold roll. The mold roll 215 also includes multiple, circumferentially spaced molding recesses 250 . As a result, the fastener product sheet molded in the process includes multiple, longitudinally spaced apart head elements and/or holes defined by the head elements. [0107] Referring to FIG. 24 , the mold roll 215 includes wedge-shaped molding cavities 252 to mold wedge-shaped fastener projections. The cavities 252 include a first planar surface that extends inward from the peripheral surface of the mold roll 215 at a decline relative to the peripheral surface. The cavities 252 include a second surface that extends inward at a decline substantially steeper than the decline of the first surface. The first and second surfaces join together at their distal ends within the cavities 252 . In some embodiments, the second surface is curved to form a projection having a curved wall. [0108] Referring to FIG. 25 , the molding recesses 250 include an outer recessed portion 271 to form the head element and an inner unrecessed portion 272 to form the hole within the head element. The inner unrecessed portion 272 includes a recess 273 that extends inward at an angle relative to the side surfaces of the head elements for forming the restraining arm that extends from the head element. In the embodiment discussed above, the molding cavities 252 and recesses 250 are each located in the mold roll 215 . In alternative embodiments, the pressure roll 220 can define the molding recesses 250 and cavities 252 . Similarly, the recesses 250 and cavities 252 can be located, in various combinations, in both the mold roll 215 and the pressure roll 220 . [0109] Referring to FIG. 26 and 27 , a fastener product sheet 640 formed using the apparatus shown in FIG. 17 includes a central region 655 and two end regions 660 , 665 . The central region 655 includes a base 615 from which multiple horizontal lanes of fastener projections 630 A extend. The edge regions 660 , 665 include longitudinally spaced head elements 610 that define longitudinally spaced holes or apertures 645 . The fastener product sheet 640 can be separated along predetermined frangible boundaries 699 (e.g., perforated regions) to create multiple, discrete fastener products similar to the fastener product 600 A shown in FIG. 22 . Any of the separating methods discussed above can be used to create the discrete fastener products [0110] Referring to FIG. 28 , a tubular fastener component 350 includes a resilient material 356 , e.g., a foam, or an elastomer, sandwiched between a tubular structure 354 , and a base 352 that includes array of wedge-shaped, engageable elements extending from a first side 352 . The second side 362 of base 352 is bound to the compliant material 356 , e.g., is integral with, or is bound with an adhesive. The array of wedge-shaped, engageable elements each have an engageable side 364 , and a non-engageable side 366 , like those shown in FIG. 1 . Structurally rigid tubular fastener component 370 with has a wall from which wedge-shaped, engageable elements extend. The orientation of the engageable elements that extend from component 370 are generally opposite of those of component 350 . The outer diameter of component 350 is oversized relative to the inner diameter of component 370 . When component 350 is inserted into component 370 in direction 372 , the resilient material allows for radial flex of the engageable elements in directions 371 , 373 as they slide past the engageable elements of component 370 , springing back into regions 374 . This spring-type action ensures good engageability of the engageable elements. [0111] Other embodiments have also been considered. For example, while fastener components having identical elements have been shown in the figures and discussed above, in some cases the fastener components may include elements having different geometries. While hollow tubular components having fastener elements on their inner and outer surfaces have been shown and discussed above ( FIG. 11 ), a solid, injection molded male part in some cases is advantageous. The hooks in the embodiment shown in FIG. 17 may be oriented differently. For example, the hooks may all be oriented in the same direction. [0112] Other embodiments are within the scope of the following claims.

A fastener element with a sheet-form base and an array of wedge-shaped engageable elements molded integrally with a surface of the sheet-form base. The wedge-shaped elements each have a steep side and a gradually rising side, and are arranged with their steep sides all directed in a common sense, such that the array can engage a similar array of oppositely-directed wedge-shaped elements to resist shear motion. The distal edges of the wedges are curved in top view.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a charged particle beam apparatus with a power source unit of a high voltage and a high power output, which is capable of instantaneous self-restoration of a load-short-circuit caused by an electric discharge. 2. Description of Prior Art FIG. 5 is a diagram showing the construction of an electron-beam welding apparatus as an example of conventional apparatuses. In FIG. 5, a reference numeral 1 designates a controllable power source for an inverter, a numeral 2 designates a booster transformer connected to the output side of the controllable power source 1, a numeral 3 designates a rectifying circuit to rectify an alternating current output from the controllable power source 1, a numeral 4 designates a smoothing reactor, a numeral 5 designates a smoothing capacitor, a numeral 6 designates a cathode of a welding machine, a numeral 7 designates an anode of the welding machine, a numeral 8 designates an electron beam emitted from the cathode 6, a numeral 9 designate a Wehnelt electrode for controlling the current intensity of the electron beam 8, a numeral 10 designates a workpiece irradiated by the electron beam 8, a numeral 11 designates a controllable biasing power source which applies a voltage to the Wehnelt electrode 9, a numeral 12 designates an insulating transformer which supplies a power to the controllable biasing power source 11 to keep it at a high potential, a numeral 13 designates a detecting resistor to detect beam accelerating voltage V A , a numeral 14 designates a constant-voltage controlling circuit for the beam accelerating voltage V A , a numeral 15 designates a detecting resistor to detect a power source current I K , a numeral 16 designates a constant-current controlling circuit for the power source current I K , a numeral 17 designates optical fibers for transmitting an output of the constant-current controlling circuit 16 to the controllable biasing power source 11 at a high potential, and a numeral 18 designates a load-short-circuit (hereinbelow referred to as arcing) produced between the anode 7 and the Wehnelt electrode 9 or the cathode 6. FIG. 6 is a diagram showing the construction of the constant-voltage controlling circuit 14 or the constant-current controlling circuit 16. In FIG. 6, a reference numeral 19 designates a feedback signal supplied from the detecting resistor 13 for the beam accelerating voltage V A or the detecting resistor 15 for the power source current I K , a numeral 20 designates a low-pass filter for removing noises contained in the feedback signal, a numeral 21 designates a set signal, a numeral 22 designates a comparator for comparing the feedback signal 19 with the set signal 21, and a numeral 23 designates a controlled signal. FIGS. 7 and 8 respectively show voltage and current waveforms appearing at each part of the apparatus when the arcing 18 takes place. In FIGS. 7 and 8, a symbol V A represents a beam accelerating voltage, a symbol I O represents a power source output current of the controllable power source 1, which is shown by an envelope of the peaks of a high frequency waveform, a symbol I K represents a power source current, a symbol I C represents a beam current, symbols t represent time, a reference numeral 24 represents generation of the first arcing, a numeral 25 represents generation of the second arcing and a numeral 26 represents interruption of the power source. FIG. 9 shows a defect in a weld bead due to generation of the arcing, in which a reference numeral 27 designates a configuration of the surface of the weld bead, a numeral 28 designates a weld line, and a numeral 29 designates a longitudinal cross-sectional view of the weld bead. The operation of the conventional control system for a charged particle beam apparatus will be described with reference to FIGS. 5 to 9. In FIG. 5, an electric power supplied from the controllable power source 1 is stepped up in the booster transformer 2, then rectified by the rectifying circuit 3 and thereafter, smoothed by the smoothing reactor 4 and the smoothing capacitor 5. The smoothed power is supplied across the cathode 6 and the anode 7, thus resulted electron beam 8 irradiating the workpiece 10. The current intensity of the electron beam 8 is controlled by a biasing voltage of the controllable biasing power source 11, which is applied across the Wehnelt electrode 9 and the cathode 6. The biasing voltage is supplied from the insulating transformer 12 and the controllable biasing power source 14 and is overlapped to the beam accelerating voltage V A . The controllable biasing power source 11 is controlled by, for instance, optical fibers 17. The beam accelerating voltage V A is detected by the detecting resistor 13 for the beam accelerating voltage V A to be controlled by the constant-voltage controlling circuit 14. The beam current I C (which is equivalent to the power source current I K under the condition other than generation of arcing) is detected by the detecting resistor 15 for the power source current I K to be controlled by the constant-current controlling circuit 16. Control of constant voltage and constant current is performed in such a manner that as shown in FIG. 6, difference between the feedback signal 19 and the set signal 21 is detected by the comparator 22 and a controlled signal 23 as an output of the comparator 22 is used so that the feedback signal 19 and the set signal 21 become equal by changing, for instance, a duty of an inverter when the beam accelerating voltage V A is controlled, or by changing the biasing voltage of the controllable biasing power source 11 through the optical fibers 17 when the power source current I K is controlled. In this case, when a welding operation is carried out, metallic vapor produced from a molten part of the workpiece 10 flows in a space between the anode 7 and the cathode 6 or the Wehnelt electrode 9, whereby there frequently causes arcing 18 due to a short circuit between both the electrodes. The arcing 18 in vacuum condition occurs with pulsation and is completed in about 100 μs. FIG. 7 shows voltage and current waveforms appearing specified parts in the welding machine at the time of generation of the arcing 18. The beam accelerating voltage V A once becomes zero volt when generation of the arcing 18 is finished since there is no electric charge in the smoothing capacitor 5. However, the power source output current I O of the controllable power source 1 is rapidly increased owing to the constant-voltage control and both the beam accelerating voltage V A and the power source output current I O are largely changed by a time constant (several m sec.) determined by the smoothing reactor 4 and the capacitor 5. In addition, when the arcing 18 takes place, an arcing current having a high peak value is overlapped on the power source current I K which is detected to control the beam current I C . Accordingly, the constant-current controlling circuit 16 functions so as not to flow the beam current I C even though there is in fact no beam current I C . Accordingly, the power source current I K and the beam current I C largely varies after generation of the arcing 18 by the influence of the change in the beam accelerating voltage V A . Thus, when the arcing 18 is once generated, the control of voltage and current becomes unstable in transition time and high voltage and current are produced. Accordingly, the second arcing 18 and the third arcing 18 are produced as shown in FIG. 8, and the output current I O of the controllable power source 1 is remarkably increased, whereby an interruption circuit for the controllable power source 1 is actuated to stop the welding operation. FIG. 9 shows a configuration of the weld bead when the arcing 18 takes place. When the arcing 18 is once generated, the beam accelerating voltage V A and the beam current I C are largely changed even though the power source does not stop. As a result, the width of the bead and the depth of penetration are largely varied. Particularly, when the power source is suddenly stopped due to generation of the arcing 18, molten metal is not supplied to a thin and deep hole formed by the electron beam to fill it to thereby create a deep crater. Repair of the crater is troublesome. To improve unstableness in a control system caused by generation of the arcing, it is considered that the frequency of the low-pass filter 20 is reduced with respect to the feedback signal 19 so that response of the control system becomes sufficiently slow, whereby interruption for the power source is delayed. However, this method sacrifices controllability of the beam accelerating voltage V A and the beam current I C in normal condition. There has been employed a method in which an irradiation path of the electron beam 8 is curved by means of a magnetic field to thereby reduce the metallic vapor entering in the space between the cathode 6 and the anode 7. However, it has been impossible to reduce the probability of generation of the arcing to zero. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control system for a charged particle beam apparatus which does not bring about the stoppage of a power source due to increase in a beam accelerating voltage and a beam current in spite of generation of arcing, whereby defect in a workpiece can be avoided. The present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in a feedback control line is fixed at a predetermined value corresponding to the feedback signal under the condition before occurrence of the load-short-circuit, and then, the fixed feedback signal is released to continue the feedback control. Another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in a feedback control line is fixed at a predetermined value corresponding to the feedback signal under the condition before occurrence of the load-short-circuit; thereafter, the fixed feedback signal is released for the continuation of the feedback control, and application of the beam accelerating voltage is stopped at the time of load-short-circuiting, followed by reopening the application of the beam accelerating voltage before continuing the feedback control. Another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage and a controllable biasing power source in the beam generating part, which is subject to feedback control by a power source current flowing in a power feeding circuit of the controllable power source, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in each feedback control line for the controllable power source and the controllable biasing power source is fixed at a predetermined value corresponding to each of the feedback signals under the condition before occurrence of said load-short-circuit, and then, each of the feedback signals is released to continue the feedback control. Still another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage and a controllable biasing power source in the beam generating part, which is subject to feedback control by a power source current flowing in a power feeding circuit of the controllable power source, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in each feedback control line for the controllable power source and the controllable biasing power source is fixed at a predetermined value corresponding to each of the feedback signals before occurrence of the load-short-circuit; thereafter, each of the feedback signals is released to continue the feedback control, and application of the beam accelerating voltage is stopped at the time of the load-short-circuiting, followed by reopening the application of the beam accelerating voltage before continuing the feedback control. BRIEF DESCRIPTION OF DRAWING FIG. 1 is a diagram of an embodiment of a control circuit for a beam accelerating voltage and a power source current of the present invention; FIG. 2 is waveforms of the voltage and current appearing at specified parts in FIG. 1 when a load-short-circuit occurs; FIG. 3 is a diagram of another embodiment of the control circuit for a beam accelerating voltage and a power source current according to the present invention; FIG. 4 shows waveforms of voltage and current appearing at specified parts in FIG. 3 when a load-short-circuit occurs; FIG. 5 is a diagram showing a construction of a conventional electron beam welding machine; FIG. 6 is a diagram of a conventional control circuit for a beam accelerating voltage and a power source current; FIGS. 7 and 8 respectively waveforms of voltage and current appearing at specified parts of the conventional apparatus when a load-short-circuit occurs; and FIG. 9 is a schematic view showing defect of weld bead caused by generation of load-short-circuit in the conventional apparatus. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to drawing. FIG. 1 is a diagram of the constant-voltage and constant-current control circuit of an embodiment according to the present invention. FIG. 1 is a diagram showing the construction of a constant-voltage and constant-current control circuit. A reference numeral 19a designates a feedback signal from a power source current I K , a numeral 19b designates a feedback signal from a beam accelerating voltage V A , a numeral 20a designates a low-pass filter for the feedback signal 19a of the power source current, a numeral 20b designates a low-pass filter for the feedback signal 19b of the beam accelerating voltage V A , a numeral 30 designates a detecting circuit for detecting generation of arcing 18 according to the feedback signal 19b of the beam accelerating voltage V A , a numeral 31 designates a trigger pulse output from the detecting circuit 30 as soon as the arcing 18 takes place, a numeral 32 designates a monostable multivibrator actuated by the trigger pulse 31, a numeral 33 designates a pulse-width determining device for the monostable multivibrator 32, a numeral 34a designates a sampling-hold circuit for the feedback signal 19a of the power source current I K , a numeral 34b designates a sampling-hold circuit for the feedback signal 19b of the beam accelerating voltage V A , and a symbol V H indicates a holding signal which is output from the monostable multivibrator 32 to keep the sampling-hold circuits 34a, 34b inactive. A symbol V AO indicates an output signal of the sampling-hold circuit 34b, a symbol I KO indicates an output signal of the sampling-hold circuit 34a, numerals 21a and 21b indicate set signals, a numeral 22a designates a comparator for comparing the output signal of the sampling-hold circuit 34a with the setting signal 21a, a numeral 22b designates a comparator for comparing the output signal of the sampling-hold circuit 34b with the setting signal 21b, a numeral 23a designates a controlled signal of the power source current I K and a numeral 23b is a controlled signal of the beam accelerating voltage V A . FIG. 2 shows voltage and current waveforms appearing at specified parts of the welding machine according to the present invention when the arcing 18 takes place. FIG. 1 is a circuit diagram of an embodiment of the present invention, which corresponds to the constant-voltage control circuit 14 and the constant-current control circuit 16 as shown in FIG. 5. The construction other than the control circuits 14, 16 can be employed for the embodiment of the present invention. The operation of the embodiment of the present invention will be described with reference to FIGS. 1 to 4. On generation of the arcing 18, the beam accelerating voltage V A and the power source current I K suddenly vary. Accordingly, when the feedback signal 19b of the beam accelerating voltage V A is input to the detecting circuit 30 composed of a comparator or a differential circuit to detect generation of the arcing, the trigger pulse 31 indicative of the generation of the arcing 18 is produced. When the monostable multivibrator 32 receives the trigger pulse 31, it generates the holding signal V H for the sampling-hold circuits 34a and 34b whereby the feedback signal 19a of the power source current I K and the feedback signal 19b of the beam accelerating voltage V A are held. In this case, it is unnecessary for the feedback signal 19b to be passed through the low-pass filter 20b because the detecting circuit 30 deals the feedback signal 19b having a large variation quantity of the generation of arcing 18 and therefore, the function of the detecting circuit 30 is not influenced even though there is some quantity of noise. Accordingly, the holding signal V H is quickly input in the sampling-hold circuits 34a, 34b whereby the feedback signal 19a of the power source current I K and the feedback signal 19b of the beam accelerating voltage V A having respective values at the time of generation of the arcing 18 can be held (the level of signals is substantially at the value just before generation of the arcing 18 because the low-pass filters 20a, 20b are provided). In other words, when the arcing 18 is generated, control is carried out by the feedback signals 19a, 19b having normal values just before generation of the arcing 18, and the quantity of sudden change in the beam accelerating voltage V A and the power source current I K after generation of the arcing 18 is neglected. Accordingly, a control system of this embodiment can be operated in a stable manner. The beam accelerating voltage V H is returned to the normal condition within several ms although time of return is determined by a time constant given by the smoothing reactor 4 and the smoothing capacitor 5. Accordingly, holding time can be determined to be 20 ms by adjusting the pulse-width determining device 33. Namely, the control circuit of the present invention is operated in such a manner that when arcing 18 takes place, change in control is made from an ordinary feedback control to an open control in which data just before generation of the arcing 18 is used, and the feedback control is again initiated after the beam accelerating voltage V A and the power source current I K are returned to substantially normal values. Even though there is generally large variation in the open control, the open control according to this embodiment is based on data of feedback control just before generation of the arcing 18, and further, the period of the open control is short as much as several tens ms or less. Accordingly, the open control of this embodiment is highly accurate as the feedback control. FIG. 2 shows voltage and current waveforms. When the arcing 18 takes places, the sampling-hold circuits 34a and 34b are actuated. A beam accelerating voltage signal V AO and a power source current signal I KO input in a control circuit do not show substantial change and the beam accelerating voltage V A and the power source current I K are smoothly returned to normal condition. A slight change occurs when the feedback control is started again in order to correct errors resulted in the open control. Accordingly, the output current I O of the controllable power source 1 does not substantially change and there causes no interruption of the controllable power source 1. In this embodiment, the beam accelerating voltage V A and the beam current I C are interrupted for about 10 ms. However, when the speed of welding in typical 6 kW and 100 kW welding machines are respectively determined to be 1 m/min and 0.3 m/min, the distance of movement of electrode in the interruption time of the beam accelerating voltage V A and the beam current I C are respectively 170 μm and 50 μm. Accordingly, no defect is found in welded portion even though there is a trace on the surface of a weld bead. In the above-mentioned embodiment, a control system is constituted by the sampling-hold circuit 34b for the feedback signal 19b of the beam accelerating voltage V A and the sampling-hold circuit 34a for the feedback signal 19a of the power source current I K . However, the object of the present invention can be attained by constructing the control system by only the sampling-hold circuit 34b for the feedback signal 19b of the beam accelerating voltage V A . The values of the feedback signals 19a and 19b are not always the same as values just before generation of the arcing 18. The same effect can be obtained by a value lower than a value just before generation of the arcing 18 due to the delay of the holding signal V H . In the above-mentioned embodiment, the controllable power source 1 which may be a power source for an inverter is actuated even if the arcing 18 takes place. However, it may be such construction as shown in FIG. 3 that the power source is instantaneously stopped. This construction is effective in the case that the operational frequency of the inverter is so high that the arcing 18 of, for instance, about 100 μs to about 1 ms may occurs again when the beam accelerating voltage V A is immediately returned to normal condition. In FIG. 3, when the trigger pulse 31 indicative of generation of the arcing 18 is input another monostable multivibrator 32c, a pulse V S is produced to instantaneously stop the inverter. Preferably, the time for stopping the inverter is determined by adjusting the pulse-width determining device 33c so as to be several ms. The outputs of a PID (proportion-integration-differential) circuit 35 for giving constant-voltage control to the beam accelerating voltage V A and a PWM (pulse-width-modulation) circuit 36 is instantaneously interrupted by a pulse V S for instantaneously stopping an inverter. Accordingly, it is possible to stop supply of the beam accelerating voltage V A for a suitable time as shown in a waveform in FIG. 4. In the above-mentioned embodiment, data of the feedback signal 19 in the condition just before generation of the arcing 18 is held by utilizing time delay of the feedback signal 19 by means of the low-pass filter 20. However, it is possible to use the pre-trigger function of a digital type waveform memory device in which the feedback signal 19 is successively written in a RAM, and data in the condition just before generation of the arcing 18 can be read out when the trigger pulse 31 is input. Description has been made as to a control system for an electron beam welding machine as an example of the present invention. However, the same effect can be obtained in a charged particle beam apparatus of a high voltage, e.g. an ion implantation device. In this case, it is possible to minimize adverse affect against a workpiece during arcing. As stated above, the control system for a charged particle beam apparatus of the present invention is so constructed that when generation of arcing is detected, feedback signals of the beam accelerating voltage and the power source current are held at predetermined values corresponding to the feedback signals in the condition just before generation of the arcing and open control is carried out for several tens ms until the beam accelerating voltage and the power source current are returned to normal condition, and thereafter, feedback control of a high speed is restarted. Accordingly, the control system is operated in a stable manner even in the arcing and the controllable power source can be automatically returned within a short time whereby any defect takes place in the workpiece which is subject to irradiation of the electron beam.

A feedback signal of a beam accelerating voltage, which is input into a feedback control system is fixed at a predetermined value corresponding to a signal under the condition before generation of arcing, when the arcing is generated, and thereafter, the fixed feedback signal is released to continue a feedback control.

BACKGROUND OF THE INVENTION This invention relates to an ignition coil unit for an internal combustion engine and, more particularly, to an ignition coil unit in which an ignition coil and a power switch for controlling a primary current through the ignition coil are integrally combined into a unit. FIG. 4 is an electrical circuit diagram of a known ignition coil unit for an internal combustion engine. The ignition coil unit comprises an ignition coil A having a primary winding 2 and a secondary winding 6, and a power switch circuit B having a plurality of electric and electronic circuit components. In FIG. 4, it is also seen that an electric source C and an ignition signal control circuit D are connected to the ignition coil unit. The power switch circuit B comprises a power transistor 1 for switching a primary current flowing through the primary winding 2 of the ignition coil A, a current limiting circuit 4 and a current detecting circuit 3 for detecting a potential difference generated by the primary current and for transmitting a primary current control signal to the current limiting circuit 4. FIG. 5 is a front view of the known ignition coil unit before it is filled with insulating resin, and FIG. 6 is a sectional side view of the ignition coil unit illustrated in FIG. 5 in which the ignition coil A and the power switch circuit B are integrally combined. In FIGS. 5 and 6, the secondary winding 6 of the ignition coil A is disposed within a casing 5 and concentrically wound around the primary winding 2 of the ignition coil A and an iron core 7. Thus, the ignition coil A is composed of the primary winding 2, the secondary winding 6 and the iron core 7. The iron core 7 is substantially C-shaped member having a pair of substantially U-shaped members welded together at an end of one of the legs of the U positioned in an opposing relationship. An air gap 7a is defined between opposing legs of the U-shaped members. One leg 7b of each of the U-shaped members is much longer than the other leg 7c and the air gap 7a is not centrally located with respect to the ignition coil A. A heat dissipating plate 22 made for example of aluminum is disposed in the casing 5 and a packaged power switch circuit 23 having the power switch circuit B therein is attached to the heat dissipating plate 22. The packaged power switch circuit 23 comprises a mold resin, 23a hermetically sealing and packaging the power switch circuit B into a single unitary piece by the transfer molding. A connector 8 is integrally molded with the casing 5. As illustrated in FIG. 6, an electrically insulating resin 9 is filled within the casing 5. As seen from FIGS. 5 and 6, the connector 8 has a plurality of connector terminals 11, 13, 15, 18. The first connector terminal 11 is electrically connected to the one end of the secondary winding 6 through a secondary winding ground line 10 and the second connector terminal 13 is electrically connected to the one end of the primary winding 2 through a source line 12. The third connector terminal 15 is electrically connected to a base terminal 16 of the power transistor 1 (See FIG. 4) in the power switch circuit B within the packaged power switch circuit 23 through a control signal line 14. The fourth connector terminal 18 is electrically connected to a ground terminal 19 of the power switch circuit B through a ground line 17. A collector terminal 21 of the power transistor 1 is electrically connected to the other end of the primary winding 2 through a collector line 20. In the known ignition coil unit as described above, the primary current of the primary winding 2 flows through the current detection circuit 3, where the current level is detected as the potential difference upon which a control signal is supplied to the current limiting circuit 4. The current limiting circuit 4 controls the primary current flowing through the primary winding 2 of the ignition coil A in accordance with this control signal. In response to this primary current flowing through the primary winding 2, a high voltage to be supplied to a distributor (not shown) is generated in the secondary winding 6 of the ignition coil A. With the known ignition coil unit as described above, after the packaged power switch 23 and the primary and secondary windings 2, 6 are mounted within the casing 5, electrical connections such as the connections between the connector terminals 11, 15, 18, 13 of the connector 8, the primary and secondary windings 2, 6 of the ignition coil A and the power switch circuit B must be provided through separate electrical conductors 10, 12, 14, 17, 20 within the limited space in the casing 5. Therefore, the ignition coil unit cannot be easily and speedily assembled, and these connecting portions sometimes fail to be tightly and correctly connected, and thus may be easily damaged. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide an ignition coil unit for an internal combustion engine free from the above-discussed problems of the known ignition coil unit. Another object of the present invention is to provide an ignition coil unit which can be easily assembled and reliable. A further object of the present invention is to provide an ignition coil unit which simplifies the connecting processes between the ignition coil and the power switch circuit. With the above objects in view, the ignition coil unit of the present invention comprises a coil assembly having an ignition coil, a power switch circuit having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil and a terminal conductor for electrically connecting the coil assembly to an external circuit, and an electrically insulating transfer-molded resin disposed around the coil assembly for supporting therein the coil assembly. Further, the ignition coil, the power switch circuit and the terminal conductor are mechanically connected into the coil assembly. The present invention also resides in a method for manufacturing an ignition coil unit, comprising the steps of preparing an ignition coil and a power switch circuit having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil, electrically connecting the power switch circuit and the ignition coil into a coil assembly and transfer-molding an electrically insulating resin around the coil assembly for hermetically sealing and supporting therein the coil assembly. The method further comprises the step of mechanically connecting the ignition coil and the power switch circuit together. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more readily apparent from the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which: FIG. 1 is an exploded perspective view illustrating one embodiment of an ignition coil unit of the present invention; FIG. 2 is a perspective view of the ignition coil unit illustrated in FIG. 1; FIG. 3 is a sectional view of the ignition coil unit illustrated in FIGS. 1 and 2; FIG. 4 is a circuit diagram of a known ignition coil to which the present invention is applicable; FIG. 5 is a front view of a known ignition coil unit before it is filled by a filler resin; and FIG. 6 is a sectional view of a known ignition coil unit illustrated in FIG. 5. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate an embodiment of an ignition coil unit of the present invention which comprises an electrically insulating transfer-molded resin 50 and a coil assembly 55 disposed within the transfer-molded resin 50. The coil assembly 55 is composed of an ignition coil A and a power switch circuit 30 which are mechanically and electrically connected to each other as illustrated in FIG. 3 showing a sectional view of the ignition coil unit. The power switch circuit 30 comprises a plurality of electric and electronic components (not shown) which compose the power switch circuit B illustrated in FIG. 4 including the power transistor 1 and the current limiting circuit 4 and the like. The power switch circuit 30 also comprises a mold resin for hermetically sealing therein these electric and electronic components. In this embodiment, the power switch circuit 30 which is previously molded with the mold resin, that is, the packaged power switch circuit 30 as illustrated in FIGS. 1 and 3 is used. However, the non-packaged power switch circuit which is not molded may be used. The ignition coil A has a primary winding 2 and a secondary winding 6 concentrically wound around the primary winding 2. Inserted into the primary winding 2 is an iron core 7 and the substantially C-shaped iron core 7 has a pair of substantially U-shaped members 71, 72 which are welded together at an end of one of the legs of the U positioned in an opposing relationship. As illustrated in FIG. 3, one leg 7b of the iron core 7 is much longer than the other leg 7c and an air gap 7a between the legs 7b and 7c is not centrally located with respect to the ignition coil A, but is positioned close to one of axial ends of the ignition coil A. Then, as the packaged power switch circuit 30 is relatively remote from the air gap 7a, a heat generated at the air gap 7a does not affect the packaged power switch circuit 30. As illustrated in FIG. 1, the packaged power switch circuit 30 is mounted on a holder 35 and supported by means of a pair of supporting plates 36 extending upwardly from the bottom of the holder 35 along the opposite side surfaces of the packaged power switch circuit 30. Disposed between the packaged power switch circuit 30 and the holder 35 is a heat dissipating plate 34 made for example of aluminum and attached to the packaged power switch circuit 30. The packaged power switch circuit 30 may be, if necessary, covered with cover means 30a such as a silicone sheet for protecting from and absorbing stress caused therebetween. The packaged power switch circuit 30 has a base terminal 31, a ground terminal 32 and a collector terminal 33 which extend outwardly from the mold resin of the packaged power switch circuit 30 and are partitioned by partition walls 37 provided to the holder 35. The partition walls 37 extend from the holder 35 parallel to the terminals 31, 32, 33. A connector 8 is integrally molded with the casing 50 as illustrated in FIG. 2. The connector 8 has a plurality of connector terminals 40, 41, 42, 43, 44. The first connector terminal 40 is electrically connected to the one end of the secondary winding 6 and the second connector terminal 41 is electrically connected to the one end of the primary winding 2 and the third connector terminal 42 is electrically connected to the base terminal 31 of the packaged power switch circuit 30. The fourth connector terminal 43 is electrically connected to the ground terminal 32 of the packaged power switch circuit 30. The terminal 44 electrically connects the collector terminal 33 of the packaged power switch circuit 30 to the other end of the primary winding 2. As illustrated in FIG. 3, a secondary terminal 45 is electrically connected to the other end of the secondary winding 6 for supplying a high voltage generated in the secondary winding 6 to the distributor (not shown). The secondary terminal 45 comprises an outer case 45a illustrated in FIG. 2 which can be integrally manufactured by the transfer-molding at the time when the transfer-molded resin 50 is manufactured. Thus, the packaged power switch circuit 30 and the ignition coil A are electrically connected to each other through these terminals. As illustrated FIG. 1, the holder 35 has a recessed coupler 46 for receiving a projection 47 provided on the ignition coil A. The projection 47 has a substantially T-shaped cross-section and snugly fit into the recessed coupler 46 so that a relatively firm mechanical connection is established between the holder 35 and the ignition coil A. Therefore, the ignition coil A and the packaged power switch circuit 30 are mechanically connected to each other through the holder 35. In the manufacture of the ignition coil unit of the present invention as described above, firstly, the packaged power switch circuit 30 and the ignition coil A are mechanically connected to each other by means of the recessed coupler 46 of the holder 35 and the projection 47 of the ignition coil A. Next, the terminals 31, 32, 33 of the packaged power switch circuit 30, the primary and secondary windings 2, 6 of the ignition coil A, the connector terminals 40, 41, 42, 43, 44 and the secondary terminal 45 are electrically connected to each other to assemble the united coil assembly 55 as illustrated in FIG. 3. The united coil assembly 55 is placed and suitably supported within a mold die (not shown) so that an electrically insulating resin 50 is transfer-molded around the coil assembly 55. The transfer-molded resin 50 is formed into a configuration corresponding to the casing 5 of the unit illustrated in FIGS. 5 and 6 and comprises a main body portion accommodating the ignition coil A and the power switch circuit 30, a connector portion defining the connector 8 for external connection, and a tower portion defining the secondary terminal 45 as illustrated in FIG. 3. According to the ignition coil unit of the present invention as described above, since the packaged power switch circuit is electrically connected to the ignition coil A through the terminals and mechanically assembled into the united coil assembly 55 before they are molded within the molded resin 50, all electrical connections between them can be very easily carried out. Hence, the electrical connection processes between them becomes easy and the connecting portions can be correctly and tightly connected. Therefore the ignition coil unit of the present invention can be easily assembled and reliable. Further, the manufacture processes are improved to be efficient.

An ignition coil unit comprises a coil assembly (55) having an ignition coil (A), a power switch circuit (B) having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil (A) and a terminal conductor (8) for electrically connecting the coil assembly (55) to an external circuit, and an electrically insulating transfer-molded resin (50) disposed around the coil assembly (55) for supporting therein the coil assembly (55). Further, the ignition coil (A), the power switch circuit (B) and the terminal conductor (8) are mechanically connected into the coil assembly (55). The present invention also resides in a method for manufacturing the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control unit for controlling the schedule run of an NC machine tool. 2. Description of the Conventional Art The automatic timed control of scheduled events is a goal desired in many fields. For example, as disclosed in Laid Open Japanese Patent Publication 1-96003, the scheduling control of various units of lighting areas, energizing motors and operating various systems in buildings or factories is provided. Such goal also is desired in the automatic manufacture of products comprising one or more workpieces, including manufacture by numerical control. Conventionally, a NC machine tool is controlled by a machining program, which gives the machine tool instructions with respect to the machining of a locus on a workpiece, machining conditions and the like, and responds to a variety of input data which may be stored or registered. The sequence of reading registered information concerning the program run sequence, the number or run times, run start time, etc. for the machining program (hereinafter "machining schedule data"), the reading of registered information for a measurement program which gives a machine tool instructions in regards to measurement locus and measurement conditions and the like (hereinafter "measurement schedule data"), and the running of the machine tool in accordance with the machining schedule data and measurement schedule data is commonly called a "schedule run" of the program. FIG. 16 is a hardware configuration diagram of a conventional numerical control unit for performing a schedule run process, as disclosed in Japanese Patent Publication No. 200409 of 1989. FIG. 17 shows an example of a machining program file directory screen for the conventional numerical control unit. FIG. 18 illustrates a scheduling data screen example of the conventional numerical control unit. An embodiment of the conventional art may be described in accordance with the drawings. First the hardware configuration example may be described with reference to FIG. 16, illustrating the hardware configuration of the known numerical control unit. In FIG. 16, a processor (CPU) 111 is used for controlling the whole numerical control unit via a common bus 126 in a conventional system architecture. A ROM 112 storing a control program, a RAM 113 storing various types of data, and a non-volatile storage 114, such as a bubble memory, storing various types of data, parameters, etc, are all accessible by the CBU via the system bus 126. Within memory 114 is scheduling data 114a for determining the machining programs that are to be employed for scheduling runs and the sequence of program execution. Also connected to the system bus is a tape reader 115, used for reading a machining program, etc. from a paper tape, a display control circuit (CRTC) 116 for converting a digital signal into a display signal, a display device 116a, such as a CRT or a liquid crystal display device, and a keyboard 117 for entering various types of data. The operational elements connected to the bus include a position control circuit 118 for controlling a servo motor. Circuit 118 connects to a servo amplifier 119 for controlling servo motor velocity, of a servo motor 120. A tacho-generator 121 is used for velocity feedback, and a position detector 122, such as a pulse coder or an optical scale, receives or inputs from generator 121 and outputs a signal to control circuit 118. While these elements are required for control of each of the machine axes, only those elements used for one axis are mentioned herein. An I/O circuit 123 also connects to the bus 126 for transferring a digital signal to and from an external device, and a manual pulse generator 124 is connected into the system for moving each axis digitally. An interface circuit 125 connects to bus 126 for transferring a signal to and from the external device. An external storage device 130, which may be a hard disk unit, is coupled with the interface 125 via a communication line 131. The external storage device is not limited to the hard disk unit but may be a floppy disk unit or a card reader unit which transfers data to and from an IC card. In this configuration, a plurality of machining programs are stored in the external storage device 130, the sequence of executing the machining programs and the number of execution times are set and stored in-the non-volatile memory 114 as scheduling data 114a, and workpieces are machined according to the scheduling data 114a to allow the job shop type production of complicated workpieces. FIG. 17 provides an example of a machining program file directory screen, wherein 140 indicates a file directory screen, 141 an indication denoting the file directory screen, 142 a file number section, 143 a file name section, and 144 represents file tape lengths. By setting a cursor on the screen to the file number 0000 and pressing a "SELECT" key 145, the screen progresses to a scheduling data screen. FIG. 18 gives an example of the scheduling data screen, wherein 150 indicates a schedule data screen, 151 an indication denoting the schedule data screen, 152 a run sequence section, and 153 a run program file section. 154 indicates a program file run count section, meaning the number of workpieces to be machined. 155 indicates a currently run program file count section, meaning the number of workpieces already machined. In a preferred order for programming the machining of several work pieces, the scheduling data screen 150 is first selected and the data of the run sequence 152, the program file 153 and the run count 154 are entered to complete the scheduling data. This scheduling data is then stored into the non-volatile memory 114 as the scheduling data 114a. By later selecting and executing this scheduling data 114a, a plurality of workpieces can be machined on a predetermined number basis. Multiple pieces of such scheduling data may be created and registered in the non-volatile memory 114. The conventional numerical control unit configured as described above only executes the scheduling data in sequence and cannot achieve a scheduled run meeting complicated conditions in a practical machining environment, as described in several examples given below. In one example, an alarm condition such as tool wear, machine-generated heat, consumable part wear or a machining program error may occur during actual, long-time unattended machining. Without a schedule changing function at the occurrence of alarm, the conventional numerical control unit stops its operation on occurrence of the alarm. Hence, if a schedule command is given to machine 100 workpieces during an unattended operation at night, the occurrence of alarm at the 10th workpiece leaves the remaining 90 workpieces unmachined until the morning, when the operators return to their assigned stations. In another example, machining accuracy tends to deteriorate as the number of workpieces machined increases. This is due to the thermal deformation of the machine, tool wear, etc. in actual long-period unmanned operation. To prevent this, it is desired to add a compensation factor to the original machining data by executing a tool measurement program every time several workpieces have been machined. Since the schedule run function of the known numerical control unit does not allow the measurement program to be registered independently of the machining program, the measurement program is registered together with the machining program. Therefore, the measurement program is called every time only one workpiece has been machined, increasing wasteful non-machining time and reducing productivity. In a further example, assume that two types of parts, part A and part B, are machined by a machine tool which performs a schedule run. Also assume that two pieces of part B will be assembled to one piece of part A in a postprocess. In such a case, it is desired to machine one piece of part A and two pieces of part B as a set in order to decrease an intermediate stock between the machining process of the machine tool and the assembling postprocess. When one piece of part A and two pieces of part B cannot be mounted on one workpiece, a long list of schedule must be registered, e.g. one piece of part A and two pieces of part B, one piece of part A and two pieces of part B, . . . , in the schedule run function of the conventional numerical control unit. However, such registration is not practical because the number of schedule elements that can be registered is limited. Hence, the parts are registered in blocks, e.g. 100 pieces of part A and 200 pieces of part B. This procedure produces an intermediate stock of 100 pieces of part A between the machining process of the machine tool and the assembling postprocess. Such a large intermediate stock requirement reduces the production efficiency of the whole manufacturing line. In another example, when considering how to improve the productivity of a plant, which is not automatic in setup and chip removal work and requires an operator for machining, the warm-up time of a machine is non-production time. It is desired to have finished such warm-up in early morning, before the operator arrives at work. In addition, for example, long-time continuous machining tends to deteriorate machining accuracy due to heat generation. To prevent this, it is desired to provide predetermined machine cooling time between schedules. However, since the schedule run function of the known numerical control unit cannot provide time-of-day information for the schedule, a desirable schedule run cannot be achieved. Finally, the schedule data registration/display function known in the art is an independent function. Therefore, for example, if it is desired to correct the tool numbers of the following machining programs because tool breakage has taken place during the run of a machining program registered to the schedule, a memorandum of all the machining program numbers that follow must be made, a transition made to an edit screen from the keyboard, then the machining program numbers entered, and the machining programs corrected in the sequence written in the memorandum. Hence, a corrected machining program number error is apt to occur. SUMMARY OF THE INVENTION The present invention will overcome the aforementioned disadvantages in the conventional numerical control unit. It is an object of the present invention to provide a numerical control unit which will not stop a schedule run if an alarm occurs during the run but will change the schedule in response to the alarm to continue the schedule run. It is a further object of the present invention to provide a numerical control unit which has a schedule run function allowing a measurement program to be scheduled in addition to the scheduling of workpiece machining to ensure that the schedule run may be made for optimum measurement program execution. It is a further object of the present invention to provide a numerical control unit which will allow the machining of a plurality of workpieces to be scheduled as one set. It is a further object of the present invention to provide a numerical control unit which will allow time-of-day information to be included in the schedule and a run to be performed at desired time of day. It is a further object of the present invention to provide a numerical control unit which will allow a direct transition to be made from a schedule data display screen to a machining program edit screen, without needing to take a memorandum. The numerical control unit concerned with the first, second, third, fourth, fifth, sixth and tenth embodiments is designed to achieve the first goal and includes schedule skipping means for causing a schedule skip at the occurrence of an alarm. The numerical control unit concerned with the seventh embodiment is designed to achieve the second goal and includes a memory for storing a measurement schedule. The numerical control unit concerned with the eighth and ninth embodiments is designed to achieve the third goal and includes a memory allowing at least two or more schedule elements to be registered as one group. The numerical control unit concerned with the eleventh and twelfth embodiments is designed to achieve the fourth goal and includes a memory for storing schedules and run start time of day corresponding to the schedule, a clock and time-of-day reading means. The numerical control unit concerned with the thirteenth embodiment is designed to achieve the fifth goal and includes machining schedule specifying means, schedule display-to-edit transition means and edit-to-schedule display transition means. The schedule skipping means in the first embodiment stops current machining when an alarm occurs, skips to an executable schedule, and resumes the schedule run. The schedule skipping means in the second embodiment stops current machining when an alarm occurs, skips to a next machining program, and resumes the schedule run. The schedule skipping means in the third embodiment stops current machining when an alarm occurs, skips to a next tool change command, and resumes the schedule run. The schedule skipping means in the fourth embodiment stops current machining when an alarm occurs, skips to a next workpiece change command, and resumes the schedule run. The schedule skipping means in the fifth embodiment stops current machining when an alarm occurs, skips to a next pallet change command, and resumes the schedule run. Alarm type determining means in the sixth embodiment identifies an alarm type when an alarm occurs and activates the schedule skipping means associated with the identified alarm type. The schedule skipping means that is activated will stop the current machining, skip .to an executable schedule, and resume the schedule run. The schedule skipping means in the tenth embodiment stops current machining when an alarm occurs, skips to a specified layer, and resumes the schedule run. The memory in the seventh embodiment stores a measurement schedule corresponding to a machining schedule. In the schedule run, not only the machining schedule but the measurement schedule as well is referenced to execute a measurement cycle. The memory in the eighth embodiment allows a plurality of schedule elements to be stored as one group of schedule data. In the schedule run, the schedule elements belonging to the group are executed in sequence. The memory in the ninth embodiment allows at least one or more groups of schedule elements to be stored as one higher-level group of schedule data. In the schedule run, the lowest-level schedule elements belonging to the group are executed in sequence. The memory in the eleventh embodiment stores a schedule and run start time of day corresponding to that schedule. The clock counts the current time of day. A time of day reading means reads the current time of day from the clock, compares it with the run start time of day, and starts a schedule run when the current time of day has passed the run start time of day. The memory in the twelfth embodiment stores a schedule and run start time of day corresponding to that schedule. The run start time of day is stored as a time increment referenced from a particular time of day, for example, the preceding machining end time of day. The clock counts the current time of day. The time-of-day reading means reads the current time of day from the clock, compares it with the run start time of day, and starts a schedule run when the current time of day has passed the run start time of day. The machining schedule specifying means in the thirteenth embodiment is capable of reading the name of a machining schedule block at the cursor. The schedule display-to-edit transition means calls a machining program corresponding to the name of the machining schedule block and activates the editing means. The edit-to-schedule display transition means searches for a schedule block wherein the machining program called on the edit screen has been registered and activates the machining schedule displaying means. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hardware block diagram of a numerical control unit according to a first embodiment of the present invention. FIG. 2 is a table diagram showing a single-block structure of machining schedule data and that of measurement schedule data according to an embodiment of the present invention. FIG. 3 is a table diagram illustrating registration examples of the machining schedule data and the measurement schedule data according to an embodiment of the present invention, in connection with blocks. FIGS. 4(a) and 4(b) show main function and single-schedule block run processing flowcharts, respectively, according to an embodiment of the present invention. FIGS. 5(a), 5(b) and 5(c) show skip completion check, run start time of day wait, and machining program skip search processing flowcharts, respectively, according to an embodiment of the present invention. FIGS. 6(a) and 6(b) illustrate skip condition flag set and measurement block call processing flowcharts, respectively, according to an embodiment of the present invention. FIG. 7 shows a main schedule run setting display screen displayed on a CRT/MDI unit according to an embodiment of the present invention. FIG. 8 illustrates a "PART AB" schedule run setting display screen displayed on a CRT/MDI unit according to an embodiment of the present invention. FIG. 9 illustrates a "PART B" schedule run setting display screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 10 shows a setting display screen, wherein "PART B MEASUREMENT" has been selected for the "PART AB" schedule run, displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 11 shows a measurement schedule setting display screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 12 illustrates an "O103(DRILLING)" edit screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 13 is a specified block change processing flowchart according to an embodiment of the present invention. FIG. 14 is an open processing flowchart according to an embodiment of the present invention. FIG. 15 is a close processing flowchart according to an embodiment of the present invention. FIG. 16 is a hardware configuration diagram of a numerical control unit known in the art. FIG. 17 provides an example of a machining program file directory screen of the known numerical control unit. FIG. 18 gives an example of a scheduling data screen of the prior art numerical control unit. DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will now be described in reference to the appended drawings. In FIG. 1, a CPU 1 of a microprocessor is incorporated in a numerical control unit for executing a command in accordance with a control program written in a ROM 4, reading time of day from a clock LSI 8, transferring data to and from an SRAM 2, carrying out machine control by entering signals of a CRT/MDI unit 7 and a machine operation board 9, conducting machining locus control by sending a command to a servo control unit 5, transmitting and displaying data on the CRT/MDI unit 7, generating a voice by sending a command to a voice output device 10, transmitting various data by sending data to a communication unit 11, and receiving from a communication control unit data sent through a communication line and a modem. All of these operations are conducted via a data bus 14 that connects the CPU to other units. Specifically, a random access memory 2 for storing machining command programs, machining schedules, measurement schedules, run start time of day, etc, is backed up by a battery 3 so that the memory 2 allows the data to be stored while the power of the numerical control unit is off. The servo control unit 5 is operative for driving a motor 6, in accordance with a command from the CPU 1, which effects the operation of a machine. The CRT/MDI unit 7 is employed in the interactive control and monitoring of the numerical control unit by an operator and comprises a display for visually providing relevant information. A voice output device 10 is used for similar purposes and generates a voice or other audible message according to commands from the CPU 1. A machine operation board is operative to generate machine operation signals, such as automatic start and reset, according to the activity of the operator. The clock LSI 8 provides the current time of day and allows it to be read. The communication control unit 11 is used for transmitting data from the CPU 1 to a communication line 12 and a modem 13 in accordance with a communication protocol and transferring to the CPU 1 data sent through the communication line and the modem. Specifically, the modem 13 is connected between a telephone line and the communication control unit 11 for bidirectional communication protocol conversion, allowing data to be transferred via the telephone line to a host computer (not shown) or the like. FIG. 2 is a table illustrating the structure of one block 21 of machining schedule data and one block 22 of measurement schedule data in the first embodiment of the present invention. These blocks of data are stored in the SRAM 2. In the structure of the one block of machining schedule data: "name" indicates the name of a schedule element, wherein a part name or a program number is set. In this example, a part name "Part A" has been set; "numb" indicates the number of machining operations to be repeated. In this example, 2 has been set, representing that two pieces of part A will be machined in this schedule; "cnumb" indicates the number of machining operations already repeated. In the example, it is 1, indicating that one piece of part A has already been machined; "time" indicates time information and "t type" a type of time information If "t type" is "ABS," "time" is the absolute time of day, and if it is "INC," "time" is incremental time from a preceding schedule element. "t type" of "ABS" in this example indicates that this schedule is started at 18 o'clock; "skip" indicates a skip destination at the occurrence of alarm. "0" does not cause a skip. "NEXT" causes a skip to a next machining program, "TOOL" to a next tool change command, "WORK" to a next workpiece change command, "PALLET" to a next pallet change command, "CONDITION" to a skip destination specified by a condition, and "CLASS" to a program scheduled to be run most recently in a specified layer. "NEXT" has been set in this example; "class" specifies a layer of a skip destination when the "skip" element is specified as "CLASS". A "class" of 0 indicates an identical layer, 1 one layer up, and -1 one layer down. Since "skip" is not specified to be "CLASS" in the example, "class" is insignificant. "sub" indicates a pointer denoting a block of schedule one layer down. "sub" is 0 when there is no lower layer. The example indicates that a block "sdata10" is in a lower layer. "mes" indicates a pointer representing a block of measurement schedule. "mes" is 0 when there is no block of measurement schedule. The example shows that there is a block of measurement schedule named "mdata1." "next" indicates a pointer denoting a block of schedule to be run next. "next" is 0 when there is no schedule to be run next (i.e. a final block). The example indicates that a block "sdata" 2 will be run next. The structure of one block of measurement schedule data will now be described. "name" indicates a name of a measurement program, wherein "O9000" has been set in the example. "numb" indicates how many times a parent block of the measurement schedule block will be run before the measurement program is run once. 5 has been set in this example, indicating that 09000 is executed once every time 5 pieces of part A are machined. "cnumb" indicates a cyclic counter which counts up each time the parent block of the measurement schedule block is run and is cleared to zero every time the number set to "numb" is reached or exceeded. 1 has been set in the example, indicating that 1 piece of part A has been machined after the preceding measurement. FIG. 3 illustrates the registered examples of machining schedule data and measurement schedule data in the first embodiment of the present invention, organized in connection with the performance of their constituent blocks. In FIG. 3, "sdata1" indicates a block that is run first. "sdata1" consists of two blocks, "sdata10" and "sdata11," and further "sdata11" is made up of two blocks, "sdata110" and "sdata111." Accordingly, "sdata1" is terminated after the blocks "sdata 10," "sdata110" and "sdata111" are run several times. "mdata10" is a measurement schedule block connected to "sdata1" and is provided with a counter which counts up every time "sdata1" is executed. A measurement program is run once every set number of times. "sdata2" indicates a machining schedule block connected to "sdata1" and is run after "sdata1" is terminated. Similarly, "sdata2" is connected to "sdata3" and linked up to final "sdatan." As seen in the illustrated example, there are three classes of blocks and the various blocks are shown to exist in up to three layers. The first layer block is conventionally identified as a "parent" block while the derivative or dependent blocks in lower layers are called "child" blocks. In the illustrated example, sdata1 block 21A is a parent machining block that itself would not be machined but its derivative block sdata10 21B is a child block that is machined while its derivative block sdata11 21C is a child block that is not machined, although it further derivative blocks 21D and 21E at the lowest layer are machined. Operation of the first embodiment will now be described in connection with FIG. 4(a), which is a processing flowchart of a main function for schedule run control. This function is called when the schedule run is started, at step 400. Step 401: First, an address (&sdata1) of a first schedule block (sdata1) is assigned to a pointer local variable (point) indicating the address of the schedule block. Step 402: A "single-schedule block run" subroutine is then called using the "point" as an argument. While tracing the schedule blocks one after another, this subroutine will run all schedule blocks according to the schedule. Step 403: The schedule run is terminated. FIG. 4(b) is a processing flowchart of the single-schedule block run and begins at step 409. To this subroutine, the parent program passes the pointer local variable (point) indicating the address of the schedule block to be run. Step 410: The number of run times is first cleared to zero (cnumb=0). Step 411: A "skip completion check" subroutine is called to check if a schedule skip is complete or not. Step 412: A check is made to see if the schedule skip is being made or not. The skip is being made if a skip flag is on. Since it is not necessary to wait until the run start time of day during a skip, the processing branches to step 414. Step 413: A "wait until run start time of day" subroutine is called and the processing waits until the current time of day passes the run start time of day. Step 414: A check is made to see if there is a child block or not. There is a child block unless "sub" of the machining schedule block is 0 . If there is no child block, the processing branches to step 418 and performs a machining program run. If there is a child block, the processing progresses to step 415 and performs a child block run. Step 415: Since the child block is to be run, a global variable (classno), used to count layers for checking a layer skip, is counted up. Step 416: To run the child block, the address of the child block (point) is read from "sub" and set to the argument of the "single-schedule block run" subroutine. Step 417: The "single-schedule block run" subroutine is called and the child block and all subsequent blocks are run according to the schedule. As described above, the "single-schedule block run" subroutine is a recursive function capable of calling itself, which logically allows the blocks in an infinitely deep layer to be run according to the schedule if there is no limit to the memory size. Step 418: When there is no child block, the processing branches from the step 414. In this case, a program set to the "name" of this block is run. Hence, a "beginning of machining program search" subroutine is called and the beginning of the program set to the "name" is searched for. Step 419: If a skip is being made, the processing advances to step 420 to perform a skip search. Step 420: A "machining program skip search" subroutine is called and a search is made within the machining program found by searching for the beginning of the machining program. For example, a tool change command or a pallet change command is searched for and the skip flag is switched off. Step 421: A check is made to see if the skip is being made or not. If the skip is being made, the processing branches to step 428 since it is not necessary to run. Step 422: If a skip is not being made, a "machining program run" subroutine is called and a run is made up to the end of the machining program or until an alarm stop occurs. Step 423: A check is made to see if the run has been stopped by alarm or not. If the run has been terminated without fault, the processing branches to step 427 to run a next schedule, and the current time of day is read from the clock and assigned to a global variable (timer) for storing the run end time of day. The processing then branches to step 428. Step 424: When the run has been stopped by alarm, a "skip condition flag set" subroutine is called to set a global variable skip mode indicating a skip type and the skip flag. Step 425: To resume the schedule, the alarm is reset. Step 426: The current time of day is read from the clock and assigned to the global variable (timer) for storing the run end time of day. The processing then returns to the step 419, makes the machining program skip search, and resumes the run when the skip has been found. If it has not been found, the processing branches to step 428 during the skip and moves on to the next block. Step 428: The number of run times (cnumb) of this schedule block is counted up. Step 429: A check is made to see if the skip is being made or not. If the skip is being made, the processing branches to step 431 because measurement need not be conducted. Step 430: A "measurement block call" subroutine is called to run the measurement block. Step 431: A comparison is made between the specified number of runs to be made (numb) and the number of runs actually made (cnumb) for this schedule block to check whether the run has been made the specified number of times. If the run has not yet been performed the specified number of times, the processing branches to the step 411 to run this block again. Step 432: When the run has been made the specified number of times, a check is made to see if a next block exists or not. When "next" is 0, there is no next block. When there is a next block, the address of the next block is read from "next" and assigned to the pointer local variable (point) indicating the block address (at step 433), and the processing branches to the step 410, thereby running the next block. Step 434: Since the processing returns to the parent block when the next block does not exist, the global variable (classno) employed to count layers for checking the layer skip is counted down. Step 435: The processing returns to the function of the parent program. FIG. 5(a) is a skip completion ,check processing flowchart that begins at START step 500. Step 501: Since the skip is complete if the skip is not being made, the processing branches to step 507 and returns to the parent program. Step 502: If the skip mode is "NEXT," reaching the beginning of the single-schedule block run should cause the next program to be run. Hence, the skip flag is switched off at step 503 to complete the skip. Step 504: If the skip mode is "CLASS" and (step 505) "classno" is 0, the layer skip is complete. The skip flag is therefore switched off at step 506 to complete the skip. Step 507: The processing returns to the parent program. FIG. 5(b) is a "wait until run start time of day" processing flowchart that begins at START step 510. Step 511: A check is made to see if the time of day has been set or not. If "time" of the schedule block is not 0, the time of day has been set. Since it is not necessary to wait until the start time of day if the time of day has not been set, the processing branches to step 517 and returns to the parent program. Step 512: The "time" of the schedule block is assigned to a local variable (start-time) indicating the run start time of day. Step 513: A check is made to see if the time of day set value is an increment or an absolute value. The set value is an increment if "t-type" of the schedule block is "INC." If it is an increment, run end time of day is added to the "start-time" at step 514 to find the "start-time" on an absolute time of day basis. Since the "start-time" is already the absolute time of day if the set value is not an increment, the processing branches to step 515. Step 515: The current time of day is read from the clock. Step 516: The current time of day is compared with the "start-time" to check whether it is past the run start time of day. If the run start time of day is not yet reached, the processing branches to the step 515 and waits until the run start time of day is reached. When it is past the run start time of day, the processing advances to step 517 and returns to the parent program. FIG. 5(c) is a machining program skip search processing flowchart that begins with START step 520. Step 521: A check is made to see if the skip mode is "TOOL" or not. If it is not "TOOL," the processing branches to step 525. Step 522: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a tool change command. Step 523: If a tool change command has not been found until the end, the processing branches to step 525 without any further execution to search the next machining program for the command. Step 524: Since the tool change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, beginning with the tool change command found. Step 525: A check is made to see if the skip mode is "WORK" or not. If it is not "WORK," the processing branches to step 529. Step 526: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a workpiece change command. Step 527: If a workpiece change command has not been found until the end, the processing branches to step 529 without any further execution to search the next machining program for the command. Step 528: Since the workpiece change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, starting with the workpiece change command found. Step 529: A check is made to see if the skip mode is "PALLET" or not. If it is not "PALLET," the processing branches to step 533. Step 530: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a pallet change command. Step 531: If a pallet change command has not been found until the end, the processing branches to step 533 without any further execution to search the next machining program for the command. Step 532: Since the pallet change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, beginning with the pallet change command found. Step 533: The processing returns to the parent program. FIG. 6(a) is a skip condition flag set processing flowchart, that begins with START step 600. Step 601: The "skip" of the schedule block is checked. If the "skip" is not "NEXT," the processing branches to step 603. Step 602: If the "skip" is "NEXT," the skip flag is switched on to set "NEXT" to the skip mode. Step 603: The "skip" of the schedule block is checked. If the "skip" is not "TOOL," the processing branches to step 605. Step 604: If the "skip" is "TOOL," the skip flag is switched on to set "TOOL" to the skip mode. Step 605: The "skip" of the schedule block is checked. If the "skip" is not "WORK," the processing branches to step 607. Step 606: If the "skip" is "WORK," the skip flag is switched on to set "WORK" to the skip mode. Step 607: The "skip" of the schedule block is checked. If the "skip" is not "PALLET," the processing branches to step 609. Step 608: If the "skip" is "PALLET," the skip flag is switched on to set "PALLET" to the skip mode. Step 609: The "skip" of the schedule block is checked. If the "skip" is not "CLASS," the processing branches to step 611. Step 610: If the "skip" is "CLASS," the skip flag is switched on to set "CLASS" to the skip mode. The "class" of the schedule block is also read and set to "classno." Step 611: The "skip" of the schedule block is checked. If the "skip" is not "CONDITION," the processing branches to step 620. If the "skip" is "CONDITION," the processing branches to the step 612. Step 612: The alarm is checked. If the alarm is not a "program error," the processing branches to step 614. Step 613: Since the alarm is a "program error," the processing causes a skip to the next machining program. The skip flag is switched on and "NEXT" is set to the skip mode. Step 614: The alarm is checked. If the alarm is not a "no-tool error," the processing branches to step 616. Step 615: Since the alarm is a "no-tool error," it is desired to abandon the machining with this tool and resume the machining with a next tool. Hence, the processing causes a skip to the next tool change command. The skip flag is switched on and "TOOL" is set to the skip mode. Step 616: The alarm is checked. If the alarm is not a "tool breakage error," the processing branches to step 618. Step 617: Since the alarm is a "tool breakage error," this workpiece probably was damaged when the tool was broken. Therefore, it is desired to abandon the machining of this workpiece and resume the machining for a next workpiece. Hence, the processing causes a skip to the next workpiece change command. The skip flag is switched on and "WORK" is set to the skip mode. Step 618: The alarm is checked. If the alarm is not a "pallet loading error," the processing branches to step 620. Step 619: Since the alarm is a "pallet loading error," it seems that the pallet cannot be loaded to the machine properly or use of this pallet may be impossible. Therefore, it is desired to abandon the machining using this pallet and resume the machining employing a next pallet. Hence, the processing causes a skip to the next pallet change command. The skip flag is switched on and "PALLET" is set to the skip mode. Step 620: The processing returns to the parent program. FIG. 6(b) is a measurement block call processing flowchart which begins with START step 630. Step 631: A check is made to see if a measurement block is present or absent. The measurement block exists if "mes" of the schedule block is not 0. If there is no measurement block, the processing branches to step 637 and returns to the parent program. Step 632: Since there is a measurement block, the number of measurement block call times is counted up. "cnumb" of the measurement block indicates the number of call times. Step 633: A check is made to see if measurement is made or not. A comparison is made between "cnumb" and "numb" of the measurement block. The measurement is made if "cnumb" is equal to or greater than "numb." If the measurement is not performed, the processing branches to step 637 and returns to the parent program. Step 634: Since the measurement is carried out, the number of measurement block call times "cnumb" is cleared to zero. Step 635: To run the measurement program, the beginning of the measurement program is searched for by using the measurement program name (name) set to the measurement block as an argument. Step 636: The measurement program is run. Step 637: The processing returns to the parent program. FIG. 7 shows a schedule run setting/display screen displayed on the CRT/MDI unit 7, wherein "MACHINING NAME" indicates a setting/display section of names on a schedule basis. In this example, two schedules of "PART AB" and "PART C" have been registered. "QTY" indicates the number of schedule repetitions, and "NO. MACHINED" the number of run repetitions from when the run of "PART AB" is started finally. "START TIME" indicates reserved run start time of day or run interval time. "SKIP TYPE" indicates a type of a schedule skip caused when alarm occurs. "MEASUREMENT NAME" indicates the name of a measurement schedule block called for in a schedule run. Concerning "PART AB", 2 in the "QTY" section indicates that machining was scheduled to be repeated twice and 2 in the "NO. MACHINED" means that the machining has been repeated twice. 18:00:00 in the "START TIME" section tells that the machining was specified to start at 18 o'clock sharp. Since there is no setting in the "SKIP TYPE" section, a skip was not designated at the occurrence of alarm. Because nothing has been set in "MEASUREMENT NAME," no measurement is made after the run of "PART AB." In regards to "PART C," 100 in the "QTY" section indicates that 100 pieces have been set for machining and 58 in "NO. MACHINED" shows that 58 pieces have been machined. 00:00:40INC in the "START TIME" section means that the machining is done at intervals of 40 seconds. No setting in "SKIP TYPE" tells that an alarm-time skip is not specified. "PART C MEASUREMENT" in "MEASUREMENT NAME" denotes that the measurement schedule block "PART C MEASUREMENT" is called every time the machining of "PART C" is over. The run status of each schedule block is displayed at the left end of the screen. In this example, the run of "PART AB" is complete and that of "PART C" is being made. A horizontal line under "PART AB" is a cursor which is moved on the screen by pressing cursor keys (such as →, ←, ↑ and ↓) to select any of the display items. "PART AB" has been selected in the example. By pressing a key corresponding to "OPEN" in this state, the details of "PART AB" can be displayed. FIG. 8 shows a display screen of the detailed schedule of "PART AB." In the example, "PART AB" consists of two schedule blocks, "PART A" and "PART B." Pressing a key corresponding to "CLOSE" on this screen returns to a higher-level schedule screen shown in FIG. 7. In the example in FIG. 8, the cursor is located under "PART B," indicating that "PART B" is being selected. By pressing the key associated with "OPEN" in this state, the details of "PART B" can be displayed. FIG. 9 provides the detailed schedule of "PART B." Pressing the key associated with "CLOSE" on this screen returns to the screen in FIG. 8. According to the example in FIG. 9, the schedule block "PART B" comprises six blocks; "O100(MILLING)," "O101(ROUGHING)," "O102(STARTING HOLE)," "O103(DRILLING)," "O104(SPOT FACING)" and "O105(FINISHING)." The "SKIP TYPE" for "O100(MILLING)" is "CLASS+2" which causes a skip two classes up ("PART AB" or "PART C") when an alarm occurs. The "SKIP TYPE" for "O100(MILLING)" is "TOOL" which causes a skip to the next tool change command at the occurrence of an alarm. The "SKIP TYPE" for "O102(STARTING HOLE)" and "O103(DRILLING)" is "CONDITION" which causes a skip according to the alarm type at the occurrence of an alarm. The "SKIP TYPE" for "O104(SPOT FACING)" is "NEXT" which causes a skip to the next program ("O105(FINISHING)") at the occurrence of an alarm. The "SKIP TYPE" for "O105(FINISHING)" is "WORK" which causes a skip to the next workpiece change command at the occurrence of an alarm. Like FIG. 8, FIG. 10 gives the details of the schedule block "PART AB," wherein the cursor is located under "PART B MEASUREMENT" indicating that "PART B MEASUREMENT" has been selected. By pressing the key corresponding to "OPEN" in this state, the details of "PART B MEASUREMENT" can be displayed. FIG. 11 displays the details of "PART B MEASUREMENT" along with those of the other measurement schedule blocks. In this example, four measurement blocks, "PART A MEASUREMENT," "PART B MEASUREMENT," "PART C MEASUREMENT" and "HOLE DEPTH MEASUREMENT" are being displayed. "PROGRAM NO." denotes a measurement program number. In the example, the program number for "PART B MEASUREMENT" is "o9001." "MEASUREMENT FREQUENCY(1/SETTING)" indicates how many times the measurement block is called before the measurement program is executed once. In the example, "PART B MEASUREMENT" is made once every time the measurement block is called 100 times. "CALL COUNT" indicates how many times the measurement block has been called after the previous measurement was made. In the example, the measurement block has been called 28 times after "PART B MEASUREMENT" was made. When the measurement block is called 72 more times, measurement is made and "CALL COUNT" is cleared to zero. A run status is indicated on the left end. In the example, "PART C MEASUREMENT" is being made. Pressing the key corresponding to "CLOSE" on this screen returns to the display of the schedule block from which the selected measurement block has been called. Since "PART B MEASUREMENT" is selected in the example, the display returns to the screen in FIG. 10. In FIG. 9, the cursor is under "O103(DRILLING)." By pressing the key corresponding to "OPEN" in this state, the details of "O103(DRILLING)" are displayed. Since "O103(DRILLING)" is the lowest-level schedule block, a program as shown in FIG. 12 is displayed. FIG. 12 illustrates the details of "O0103(DRILLING)." Pressing a key associated with "CHECK" on this screen allows the plotting of an "O103(DRILLING)" program to be checked. Pressing a key corresponding to "READ" allows the machining program to be entered from an external input device. Pressing a key corresponding to "PRINT" allows the "O103(DRILLING)" program to be printed out on an external printer. Pressing a key associated with "EDIT" allows the "O103(DRILLING)" program to be edited. Pressing the key corresponding to "CLOSE" returns to the screen in FIG. 9. Processing will now be described. FIG. 13 is a flowchart of "specified block change" processing called when an up cursor key (↑) or a down cursor key (↓) is pressed on the schedule block display screen, beginning with START step 1300. Step 1301: A check is made to see if the key pressed is the up cursor key or not. If it is the up cursor key, the processing branches to step 1304 and moves the specified block one position backward. Step 1302: A check is made to see if there is a next block or not. There is a next block if the "next" of this schedule block is not 0. When there is no next block, the processing branches to step 1307 since there is nothing to be done. Step 1303: The address "next" of the next block is assigned to a pointer global variable "xpoint" indicating the address of the specified block, thereby using the next block as the specified block. The processing then returns to the parent program at step 1307. Step 1304: Since the up cursor key has been pressed, it is desired to employ a block preceding the current specified block as the specified block. Hence, the preceding block is searched for. A block of which "next" matches the current "xpoint" is the preceding block. Step 1305: If the preceding block does not exist, the processing branches to step 1307 because there is nothing to be done. Step 1306: The address of the preceding block is assigned to "xpoint", thereby employing the preceding block as the specified block. Step 1307: The processing returns to the parent program. FIG. 14 is a flowchart of "open" processing called when the key corresponding to "OPEN" is pressed on the schedule block display screen. Step 1401: A check is made to see if there is a child block in the specified block. The child block exists if "sub" of the specified block is not 0. If there is no child block, the processing branches to step 1404 and transits to an edit screen. Step 1402: Since there is a child block, "sub" is assigned to the pointer global variable "xpoint" indicating the address of the specified block, thereby using the child block as the specified block. Step 1403: The schedule block is displayed. The process then returns to the parent block at step 1406. Step 1404: Since there is no child block, the program having the program name (name) of the specified block is searched for to move to the edit screen. Step 1405: The edit screen is displayed. Step 1406: The processing returns to the parent program. FIG. 15 is a flowchart of "close" processing called when the key corresponding to "CLOSE" is pressed on the edit screen or the schedule block display screen. Step 1501: A check is made to see if the edit screen is being displayed or not. If the screen being displayed is not the edit screen (is the schedule block display screen), the processing branches to step 1504. Step 1502: The schedule block wherein the program being displayed on the edit screen is registered is searched for. The block searched for is the one having the "name" matching the program name on the edit screen. Step 1503: The address of the block found is assigned to the pointer global variable "xpoint" indicating the address of the specified block, thereby using it as the specified block. The processing then progresses to step 1507. Step 1504: A parent data block is searched for since "CLOSE" has been selected on the schedule block display screen. Blocks before the specified block are searched for a block whose "sub" is the address of the first block. This is the parent block. Step 1505: When there is no parent data block, the processing branches to step 1507 since there is nothing to be done. Step 1506: The address of the parent data block is assigned to "xpoint," thereby using the parent data block as the specified block. Step 1507: A block preceding the specified block is searched for. The schedule block of which "next" matches "xpoint" is the preceding block. Step 1508: If the preceding block is absent, it indicates that the specified block is the first block and therefore the processing branches to step 1510 and displays the schedule block. Step 1509: The address of the preceding block is assigned to "xpoint" to employ the preceding block as the specified block. To search for the first block, the processing branches to the step 1507 and repeats the following steps. Step 1510: Schedule blocks are displayed, beginning with the specified schedule block indicated by "xpoint." Step 1511: The processing returns to the parent program. According to the present invention, as described above, the schedule skipping means for skipping a schedule at the occurrence of an alarm allows machining to be continued without stopping a schedule run if an alarm occurs during the run. The memory for storing a measurement schedule corresponding to a machining schedule allows any measurement schedule to be made out, ensuring the implementation of the measurement schedule which will not impair productivity greatly. The memory capable of registering two or more schedule elements as one group allows a complicated schedule, such as the repeated machining of multiple sets of workpiece machining, to be made out easily with a small-capacity memory. The clock and the memory for storing run start time corresponding to a schedule allow run start time of day and run interval time to be set, ensuring ease of control such as an unattended warming-up run and an interval run including machine cooling time. The machining schedule specifying means, the schedule display-to-edit transition means and the edit-to-schedule display transition means allow any of schedule data displayed on a schedule registration display screen to be specified and edited and an edit screen for a machining program to be directly transited to a corresponding schedule display screen to check the schedule status of that program, ensuring ease of operation as well as preventing incorrect program edition from being made by writing and/or entering a wrong program number.

A numerical control (NC) machine tool is controlled by a machining program, which gives the machine tool instructions with respect to the machining of a locus on a workpiece, machining conditions and the like, and responds to a variety of input data which may be stored or registered in a manner that comprises a schedule run, and includes a schedule skip capability. The schedule skipping capability permits portions of the scheduled run to be skipped at the occurrence of an event, such as an alarm, but allows machining to be continued without stopping the schedule run. The scheduled run may skip to a new program, to commands for changing tools, pallets, workpieces and the like, or to conduct a measurement schedule run in association with the machining run. The memory for storing a measurement schedule corresponding to a machining schedule allows any measurement schedule to be utilized without impairing machining productivity greatly. The memory is capable of registering two or more schedule elements as one group, thereby allowing a complicated schedule, such as the repeated machining of multiple sets of workpiece machining, to be made out easily with a small-capacity memory. A clock and the memory for storing run start time corresponding to a schedule allow run start time of day and run interval time to be set for unattended operation. Schedule data may be displayed for schedule specification and editing.

FIELD [0001] The present disclosure relates to a control methodology for a wireless fluid level sensor and more particularly to a wireless oil level sensor for an internal combustion engine. BACKGROUND AND SUMMARY [0002] This section provides background information related to the present disclosure which is not necessarily prior art. [0003] It is important to maintain a proper amount of oil in an engine in order for the engine to be properly lubricated. Typically, engines are equipped with a dipstick that is manually removed from an engine in order to observe the oil level of the oil on the dipstick. Although the oil dipstick is a reliable method of detecting the oil level, it requires that the vehicle operator open the vehicle hood and pull the dipstick out of the engine. Optional engine oil switches exist that notify an operator that the oil level is low. These oil switches have to be wired into the vehicle and fixedly mounted within the oil pan at a level representative of a minimum level at which the user needs to be notified of the low oil condition. Therefore, the typical oil level sensor is only useful for providing a low oil indicator when a low oil condition exists. [0004] The present disclosure provides implementation and a control methodology of a wireless oil level sensor. The control methodology includes mounting a wireless oil pressure sensor to the oil plug of an engine. The oil pressure sensor detects a pressure which can then be used to determine a volume or level of oil above the sensor. The oil level sensor can include an accelerometer sensor that can be excited by the vibration caused by the starting of the engine to “wake up” the sensor. The sensor can take an initial pressure reading at start up and associate the pressure reading with an oil level that can then be transmitted to a vehicle control unit. The sensor can remain idle until the accelerometer sensor no longer detects engine vibrations at which time the sensor is activated to take pressure readings at predetermined time intervals and to transmit an associated oil level to the vehicle central processor until a predetermined time period has expired. The oil sensor then goes into sleep mode in order to maximize battery life. [0005] According to another aspect of the present disclosure, the oil sensor can further be utilized to detect an oil change condition and report the oil change condition to the vehicle control unit so that the oil life monitor can be automatically reset without requiring any input from the vehicle operator. [0006] According to a further aspect of the present disclosure, the oil sensor can be utilized to estimate crankcase pressure during engine operation to help service technicians determine if the crankcase ventilation system or piston rings are operating properly. [0007] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS [0008] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. [0009] FIG. 1 is a schematic view of a vehicle having an engine with a wireless oil sensor disposed in the oil pan according to the principles of the present disclosure; [0010] FIG. 2 is a schematic view of an engine with the wireless oil sensor disposed in the oil pan according to the principles of the present disclosure; [0011] FIG. 3 is a schematic view of the oil sensor mounted to the oil plug received in the oil pan; and [0012] FIG. 4 is a schematic diagram illustrating the communication between the wireless oil sensor and a vehicle control unit according to the principles of the present disclosure. [0013] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION [0014] Example embodiments will now be described more fully with reference to the accompanying drawings. [0015] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. [0016] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. [0017] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. [0018] With reference to FIG. 1 , a vehicle 10 is shown including an engine 12 having an oil pan 14 with an oil sensor 16 disposed in the oil pan. The oil sensor 16 can provide wireless signals to the vehicle central processor unit 18 which can display information to the vehicle operator via a vehicle display unit 20 . FIG. 2 shows a larger more detailed view of the engine 12 oil pan 14 with the oil sensor 16 disposed in the oil pan plug 22 . FIG. 3 shows a larger more detailed view of the oil pan plug 22 disposed in a threaded opening 24 in the bottom of the oil pan 14 and with the oil sensor 16 mounted to the oil pan plug 22 . [0019] FIG. 4 provides a schematic illustration of the components of the wireless oil sensor 16 for communication with the vehicle central processor unit 18 . The wireless oil sensor 16 includes a sensor central processor unit 30 that is in communication with a plurality of sensors that can include a pressure sensor 32 , temperature sensor 34 , an accelerometer sensor 36 , and an attitude sensor 37 . Additional sensors can be utilized. A battery 38 is provided for providing power to the wireless oil sensor 16 and an RF transceiver 40 is provided for providing signals to and transmitting signals from the central processor unit 30 . The RF transceiver 40 is capable of transmitting signals to an RF transceiver 42 of the vehicle central processor unit 18 as well as receiving signals from the RF transceiver 42 or from other programming tools 50 ( FIG. 1 ). [0020] The sensor function begins with the sensor in a sleep mode when the engine is off. When the “Key” is turned “on” or the engine is otherwise caused to turn over, the accelerometer sensor 36 is excited by the vibration of the engine and it causes the oil sensor 16 to switch to an operation/awake mode. The oil sensor 16 then immediately reads the temperature and pressure within the oil pan 14 and can convert those temperature and pressure readings into a corresponding oil level (L) at start-up. It is noted that for purposes of the discussion herein, the oil level L and sensed pressure P are used somewhat interchangeably since the sensed pressure generally corresponds to a certain oil level. Optionally, oil level can be converted to oil mass by assuming a known oil density and correcting for temperature. The sensor readings are required to be taken right away before engine operation causes the oil to be dispersed throughout the lubrication system of the engine so that the level of oil in the oil pan 14 is not representative of the amount of oil that is typically measured when the engine is off. The sensor readings are also required before the oil crankcase atmospheric pressure is affected by the engine operation. During the remaining engine operation cycle, the oil sensor 16 can remain idle. [0021] When the key is turned “off” or the engine is otherwise turned off, the excitation of the accelerometer sensor 36 is stopped. After the oil sensor 16 detects that the engine vibration has stopped via the accelerometer sensor 36 , the oil sensor central processor unit 30 initiates a clock and begins sampling the oil level at predetermined increments for a predetermined period of time. By way of non-limiting example, the predetermined increments can be 10 sec increments and the predetermined period of time can be determined based upon a typical amount of time for a majority of the engine oil to return to the oil pan 14 . This time period can range from 1 minute to several minutes for different engine designs. The oil sensor central processor unit 30 can correct the oil level for temperature and optional volume variations or mass and transmit the oil level/volume for each level read to the radio frequency transceiver 42 of the vehicle central processor unit 18 . After the predetermined time period has expired, the oil sensor 16 returns to sleep mode. [0022] The control method of the wireless oil sensor 16 enables the wireless sensor 16 to act autonomously in its environment. The wireless oil sensor is capable of sensing its own environment and can be selectively energized to measure the fluid level when it is possible for accurate measurement. The battery life of the oil sensor is maximized due to the selective operation. The control methodology of the present disclosure enables the use of a wireless engine oil level sensor and has the potential to replace the current oil level dipstick and low oil switch used in present vehicles. The system can result in cost reduction, improved oil level measurement accuracy, improved customer convenience by allowing accurate oil level information to be displayed on a vehicle display 20 . The attitude sensor 37 can be utilized to adjust the oil level reading for tilt if the vehicle is parked on a hill. Therefore, a false low oil level indication can be avoided. [0023] A further feature of the present disclosure is the ability to use the wireless oil sensor 16 to include an algorithm to recognize the environmental conditions that are unique to an oil change. In general, it is recognized that an oil level changes very slowly throughout the operation of a vehicle whereas an oil change will induce a change in oil level over a very short period of time. The oil sensor 16 is able to recognize an oil change event and communicate to the vehicle central processor unit 18 . In particular, according to one aspect of the present disclosure, the oil sensor 16 can calculate a change in oil level with respect to time (dL/dT) and determine if the value of dL/dT is less than 0 and its absolute value is greater than a threshold value, then an oil change event is identified. In other words, in the event the oil sensor 16 is mounted to the oil plug 22 , removal of the oil plug and oil sensor 16 will result in the oil sensor being activated from sleep mode by the accelerometer being excited due to the rotation and removal of the oil plug 22 . Once the oil plug 22 and oil sensor are removed from the oil pan, the oil sensor 16 will recognize an immediate drop in pressure since the pressure sensor 32 is now exposed to ambient pressure. The drop in pressure can be identified as an oil change event that can be identified to the vehicle central processor unit 18 which can either automatically update the vehicle database of the current oil change event or to prompt the vehicle operator via the display 20 to confirm that an oil change is or has been performed. As an alternative, the attitude sensor 37 can be used to detect that the oil plug was removed to signal that an oil change is being performed. The removal of the oil plug would alter the attitude of the oil plug and allow the vehicle central processor unit to discern that an oil change is being performed. [0024] If the oil sensor 16 is not mounted to the oil plug 22 , but is otherwise mounted within the oil pan 14 , the oil sensor 16 will recognize a rapid decrease in pressure over time (dL/dT) as the oil drains from the oil pan 14 . The rapid decrease in pressure over time can be determined to be representative of an oil change event that can be identified to the vehicle central processor unit 18 which can either automatically update the vehicle database of the current oil change event to reset the oil life monitor or to prompt the vehicle operator via the display 20 to confirm that an oil change is or has been performed, and then, if confirmed, can reset the oil life monitor. [0025] According to an alternative oil change check function, a repetitive knocking on the surface of the oil plug 22 in close proximity to the oil sensor 16 can be recognized by the accelerometer sensor 36 and the oil sensor 16 can transmit to the vehicle central processor unit 18 signaling an oil change event in progress. The repetitive knocking can be representative of a wrench engaging the oil plug 22 or another forced pattern that the oil change technician carries out. A repeated knocking pattern (either via re-installation of the oil plug 22 or a forced pattern carried out by the oil change technician) can then be recognized by the accelerometer 36 and the oil sensor 16 can transmit information to the vehicle central processor unit 18 to signal that the oil change event is complete so that the oil life monitor can be automatically reset, either with or without confirmation of the oil change event with the vehicle operator. The oil change detection feature provides a means by which the oil life monitor on a vehicle can be automatically reset rather than requiring vehicle operator input. [0026] According to a further aspect of the present disclosure, the oil sensor 16 located in the oil pan drain plug 22 can be used to estimate crankcase pressure during various operating conditions of the engine to determine if the ventilation system or piston rings are operating properly. Service technicians currently have to install a separate blow-by measuring device onto the engine to determine if the piston rings are not sealing properly. Service technicians also have no means of measuring the crankcase pressure to determine if the ventilation system is operating correctly. The use of the oil sensor 16 to estimate the pressure during engine operation eliminates the need to install a separate crankcase pressure sensor and/or a blow-by measurement device, which saves labor and diagnosis time. In order to use the oil sensor 16 for detecting engine operating conditions, the technician starts the engine and lets it idle. The technician uses a hand held signal monitoring device 50 ( FIG. 2 ) or vehicle display FIG. 2 to read a pressure output from the oil sensor 16 . By way of non-limiting example, pressure values lower than a normal predetermined value (e.g. −4 kPa) can indicate that the crankcase pressure regulation valve is stuck in an open position and requires service. Pressure values higher than a normal predetermined value (e.g. 3 kPa) indicate that the piston rings are not sealing properly or the pressure regulation valve is stuck closed. Accordingly, the oil pressure sensor in the oil pan can be used by service technicians to diagnose engine problems. [0027] An alternative to the technician activating the sensor using a signal monitoring device, is an “automated mode” that detects crankcase pressure periodically during engine operation and reports to the engine central processor unit 18 . The central processor unit 18 captures the signal and determines if the engine is in the required “standard” condition (e.g., warm idle). If so, the central processor unit 18 checks for pressure values being in the “normal” window. If not, the central processor unit 18 provides a signal to notify the operator of possible maintenance requirements. [0028] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

A control methodology for a wireless oil level sensor includes mounting a wireless oil pressure sensor to the oil plug of an engine. The oil pressure sensor detects a pressure which is used to determine a volume or level of oil in the oil pan. The oil level sensor can include an accelerometer sensor that can be excited by the vibration caused by the starting of the engine to “wake up” the sensor. The sensor can take an initial pressure reading at start up and associate the pressure reading with an oil level that can then be transmitted to a vehicle control unit. The sensor can remain idle until the accelerometer sensor no longer detects engine vibrations. The sensor is activated to take pressure readings at predetermined time intervals and to transmit an associated oil level to the vehicle central processor unit until a predetermined time period has expired.

This application claims the benefit of priority of U.S. Provisional Patent Application 60/745,806, filed 27 Apr. 2006, and is a continuation-in-part of U.S. patent application Ser. No. 10/672,060, filed 29 Sep. 2003. FIELD OF THE INVENTION The present invention relates to baseball bats and more particularly to tubular baseball bats, constructed of a variety of materials, and more particularly to baseball bats designed to improve player performance. More particularly, baseball bats according to the invention have variable radial stiffness along the barrel length resulting in larger sweet spots, improved batting performance as defined by greater hitting distance, a vibration soft feel, and unique sounds upon contact with a ball while meeting existing, new, or changed performance standards established by regulatory bodies. BACKGROUND OF THE INVENTION AND PRIOR ART Baseball and softball bats, hereinafter referred to simply as “baseball bats” or “bats”, are today typically made solely from aluminum alloys, or aluminum alloys in combination with composite materials (hybrid bats), or most recently solely from composite materials (with the exception of solid wooden bats for the Major Leagues). Such bats are tubular (hollow inside) in construction in order to meet the weight requirements of the end user, have a cylindrical handle portion for gripping, a cylindrical barrel portion for hitting, and a tapered mid-section connecting the handle and barrel portions. Traditionally, such bats have generally had a constant radial stiffness along their barrel portion length, measuring the radial stiffness along the barrel wall as independent annular segments of the barrel wall at any location along the barrel wall length. When aluminum alloys initially replaced wooden bats in most bat categories, the original aluminum bats were formed as a single member, that is, they were made in a unitary manner as a single-walled aluminum tube for the handle, taper, and barrel portions. Such bats are often called single-wall aluminum bats and were known to improve performance relative to wooden bats as defined by increased hit distance. More recently (in the mid 1990's), improvements in bat design largely concentrated on further improving bat performance. This was accomplished primarily by thinning the barrel wall of the single wall bat frame, and adding inner or internal, and or outer or external, secondary members extending along the entire barrel length. These members are often referred to respectively as inserts or sleeves; while the main member is often referred to as a body, shell or frame. Such bats are often called double-wall bats or multi-walled bats in the case of more than two walls resulting from two or more secondary members. Such double walled and multi-walled tubular bats generally obtained improved performance in terms of hitting distance by reason of the improved elastic deflection that is characteristic of a multilayer barrel wall. The efficient batting of a ball is maximized by minimizing plastic deformation, both within the bat and within the ball. Ideally, during the collision, the barrel wall of the bat should not deform beyond its elastic limit. Use of a multi-wall two or more member construction along the entire barrel length allows the barrel portion of the bat to elastically deflect or flex more upon ball impact which propels the ball faster and further than prior art single wall bats. The scientific principle governing improved bat performance is bending theory. When a ball impacts a bat it has kinetic energy that must be absorbed by the bat in order to stop the ball. The bat stores most of this energy by flexing. The ball as well deforms. After the ball is stopped, the bat returns the energy it has stored by rebounding and sending the ball back towards where it came from. The more the bat barrel or striking portion deforms upon ball impact without failing (denting or breaking) or experiencing plastic deformation, the lower the energy loss and the greater the energy returned to the ball from the bat as the tubular bat barrel portion impacted returns to its original shape. To allow the bat barrel portion to deform, requires lowering the radial stiffness of the barrel portion. The prior art double walled and multi-walled tubular bats have traditionally accomplished this by thinning the main member of the barrel portion and adding thin secondary member insert(s) and/or sleeve(s) which are not bonded to the main member, but which generally extend throughout the full length of the barrel portion. Such inserts and sleeves are not coupled to the barrel wall portion of the frame, and these two contacting components may slide with respect to each other in the same manner as leafs within a leaf spring. The resultant lowered radial stiffness along the barrel portion length permits the barrel wall to deflect elastically. U.S. Pat. No. 5,415,398 to Eggiman is an example of a multiwalled bat that discloses use of a frame and internal insert of constant thickness running full length of the barrel portion of the bat in a double-wall construction. Other similar bat designs are described in U.S. Pat. No. 5,303,917 to Uke which discloses a two member bat of thermoplastic and composite materials and U.S. Pat. No. 5,364,095 to Easton which discloses a two member bat consisting of an external metal tube and an internal composite sleeve bonded to the inside of the external metal tube and running full length of the barrel portion of the bat. U.S. Pat. No. 6,251,034 discloses a polymer composite second tubular member running throughout the full length of the barrel portion of the bat with the members joined at the ends only of the barrel portion with the balance of the composite member freely movable relative to the primary member. U.S. Pat. Nos. 6,440,017 and 6,612,945 to Anderson also disclose two member bats with an outer sleeve and inner shell of constant thickness running full length of the barrel portion. Other references include U.S. Pat. No. 6,063,828 to Pitzenberger, U.S. Pat. No. 6,461,760 to Higginbotham; U.S. Pat. No. 6,425,836B1 to Mizuno, and U.S. Patent Pub. 2001/0094882 A1 to Clauzin. In all the prior art multi-walled tubular bats cited so far, the bat secondary member, or insert, extends along the entire frame barrel length, have constant diameters and thickness resulting in uniform cross-sectional geometry along the secondary member length. Also, the bat members are not joined, except at their ends, in order to reduce radial stiffness of the barrel portion to improve bat performance. Also, in all cases, the radial stiffness of the barrel portion is uniform or constant full length of the barrel portion of the bats. While the prior art single member, and more particularly, double-walled and multi-walled tubular bats have demonstrated improved performance as claimed, various regulatory bodies have raised safety concerns regarding improved performance bats and thus, some have established maximum performance standards for various categories of baseball bats under their jurisdiction. As a result, manufacturers of baseball bats are required to pass various controlled laboratory tests, such as, bbf (batted ball performance), bbs (batted ball speed), etc. Further, for a given bat category (eg. slowpitch softball), there may be two or more regulatory bodies each of which may establish a different standard. Further, any of the regulatory bodies may change their standard from time to time. Such new or changed or varying regulations are extremely problematic, costly, and disruptive for both manufacturers and players. It is not generally desirable to lower the performance of a bat by simply increasing the thickness of the barrel wall of one or more of the barrel members along its full length. Lowering the performance of the bat by merely increasing the wall thickness can increase weight such that the finished bat weight standard or objective is exceeded. On the other hand, it is desirable to increase the wall thickness only in the sweetspot, or mid region, of the barrel portion of the bat without significantly increasing the weight. Therefore, what is needed is a simple, low cost invention to vary, e.g. decrease, bat performance of tubular bats in a controlled manner, in order to meet lowered or changed bat performance standard requirements without significantly increasing or departing from standard bat weight. Further, in conjunction with causing a decrease in batting performance it would be desirable to improve another bat characteristic such as “sweetspot” size. The sweet spot of a bat is generally the portion of the barrel which, with when struck by the ball, provides maximum batting performance. It is the location on the barrel at which the collision occurs with maximum efficiency and with the transmission of minimum vibration through the handle to the hands of a user. While highly subjective, many players would accept that the sweet spot portion on the bat has a dimension of approximately 2 inches, possibly up to 4 inches, in length and is located generally midway along the barrel portion. It is highly desirable to provide improved bats with a predetermined maximum allowable bat performance and a larger sweetspot region than bats of the prior art. This is one of the primary objectives of the present invention. Further, multi-wall bats of the present invention with inventive secondary members with non-uniform cross-sections along their length provide a vibration free soft feel and produce unique sounds upon contact with a ball. U.S. published patent application No. 2005/0070384 with patent application filed Sep. 29, 2003, by the inventors of the current application, addresses the larger sweetspot region objective by varying radial stiffness along the barrel length by adding a stiffener, or by changing fibre properties along the barrel length, or by thickening the barrel wall generally in the area of the sweetspot. U.S. Pat. No. 6,949,038 issued to Fritzke filed Jan. 21, 2004 also addresses this objective. The Fritzke '038 reference purports to achieve an improved sweet spot characteristic by providing a secondary member, located either inside or outside the barrel of a standard frame, wherein the secondary member has a constant outside diameter with an internal wall whose thickness increases while proceeding from its ends inwardly towards the opposing ends. Generally, this thickening is shown to increase to a maximum around the mid-portion of the length of the secondary member. In one figure, FIG. 12 , this thickness is shown to partially decrease around the mid-portion of the length of the secondary member, providing two laterally placed regions of maximum thickness on either side of the mid-portion. While the present inventor's earlier publication and the Fritzke patent represent different means of achieving an enlarged sweet spot of a baseball bat, the present invention includes other means to achieve the same result plus additional benefits regarding performance, feel and sound. Field testing has repeatedly shown that a “soft” feel upon ball impact and/or a “pleasing” sound are both player perceptions which are often favoured by the player over absolute performance as measured by hit distance. SUMMARY OF THE INVENTION Therefore, in view of the foregoing, what is needed is a tubular baseball bat with a specific distribution of variable radial stiffness along their barrel portions in order to vary bat performance along the barrel hitting portion length, to make the bat feel “soft” when striking a ball, and to produce a pleasing sound upon impact with the ball. To achieve these objectives, the bats of the present invention are stiffened in the barrel area of peak bat performance commonly referred to as the sweetspot. Typically, this is an area approximately 2″ to 4″ in width as compared to barrel portion lengths of 4″ to 16″. This is achieved by the presence of an inventive geometric secondary member, or members, with non-constant outside diameters positioned internally within the bat frame, or by independent numerous annular secondary members located along the inner surface of the barrel portion of an external bat frame, or by inserting or adding to the bat a circumferential stiffener in the region of the sweetspot, or by making the barrel wall thicker in the region of the sweetspot, or by having stiffer material in the region of the sweetspot. Such embodiments also can provide variable bat performance along the barrel length, enlarge the sweetspot size, improve bat performance, have a softer feel upon ball impacts, and produce unique pleasing sounds upon ball impact. In one embodiment of the present invention, the inventive internal secondary members have a variable outside diameter and constant wall thickness and are characterized by variations in the surface profile on one side of the secondary member wall being reflected by a corresponding profile on the other side of the secondary wall that provide at least two or more contact regions with the internal barrel portion of the frame barrel wall that in turn create at least one functional air cavity that is closed at both ends. In one variant of the invention internal secondary members have constant internal diameters. In another embodiment of the present invention, two or more independent annular or ring like, members of generally consistent cross-sectional geometry with variable dimensions and with length less than one-half the barrel portion length are internally located in unbonded contact along the inner wall of the barrel portion of an external bat frame. An additional secondary bat member of length approaching the barrel length may be located internally to the annular secondary members. In another embodiment, a short light weight polymer composite circumferential stiffener of the invention as employed adds only minimal weight to a given bat thus allowing the stiffened bat to continued to be used within the required weight requirements set by the relevant governing body. The stiffener of the present invention can be added to previously constructed tubular bats returned from players for modification to meet a changed regulation allowing such previously manufactured bats to meet a changed standard. Though somewhat heavier, a short metallic stiffener could also be employed. An alternative method of varying stiffness, and thus bat performance, along the barrel portion is to vary thickness along the barrel portion. Another alternative solution of the present invention for all composite bats is accomplished by engineering calculation considering selection of the composite fiber type, the fibre size, the angles of the fibers, and the thickness of the polymer composite stiffener to be employed to precisely lower the bat performance. While tubular bats of the present invention have variable radial stiffness along their barrel portions to achieve a specific predetermined bat maximum bat performance, it is simultaneously possible to achieve a sweetspot which is larger than the sweetspot typically found in tubular bats of the prior art. In the present invention this is accomplished by selectively radially stiffening only the peak performance area (generally the sweetspot area) of the bat to provide a radial stiffness therein which is greater than the radial stiffness of the barrel portion area immediately adjacent on both sides of the sweetspot. The resultant effect can be to approximately double the sweetspot size (that is, the area of the barrel portion which provides maximum bat performance). Further, bats of the present invention with secondary members with a variable outside diameter, with or without thickened end portions have a softer feel upon impact and produce unique impact sounds. The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which follow. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a longitudinal cross-section of a typical prior art single wall tubular bat with a singular frame, or member, construction. FIG. 1A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 1 prior art tubular bat. FIG. 2 shows a longitudinal cross-section of a typical prior art double-wall tubular bat with two separate members, a frame or main member with an internal insert as a secondary member in the barrel area. Both the frame and insert run the full length of the barrel portion and are not joined full length. FIG. 2A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 1 prior art tubular bat. FIG. 3 shows a longitudinal cross-section of a typical prior art double-wall tubular bat with two separate members, a frame or main member with an external sleeve secondary member in the barrel portion. Both the frame and sleeve run the full length of the barrel portion and are not joined full length. FIG. 3A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 3 prior art tubular bat. FIG. 4 shows a longitudinal cross-section of one embodiment of the present invention showing a single wall tubular bat in accordance with the present invention showing an internal stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 4A shows a cross-sectional area of a barrel location not within the sweetspot area. FIG. 4B shows a cross-sectional area within the sweetspot area showing the internal stiffener of the present invention. FIG. 5 shows a longitudinal cross-section of a second embodiment of the present invention showing a single wall tubular bat in accordance with the present invention with an external stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 5A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 5B shows a cross-sectional area within the sweetspot area showing an external stiffener of the present invention. FIG. 6 shows a longitudinal cross-section of a third embodiment of the present invention showing a single wall polymer composite tubular bat in accordance with the present invention showing a localized area of the fiber type and/or angle change resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6B shows a cross-sectional area within the sweetspot area showing a stiffened area of changed fiber angles and/or type. FIG. 6.1 shows a longitudinal cross section of a single wall polymer composite tubular bat in accordance with the present invention showing the alternative construction incorporating a thickened barrel wall 21 resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6.1A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6.1B shows a cross-sectional area within the sweetspot area showing a stiffened area with thicker barrel wall. FIG. 6.2 shows a longitudinal cross-section of an alternative double wall polymer composite bat in accordance with the present invention showing a localized area of the fibre type and/or fibre angle change within the insert resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6.2A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6.2B shows a cross-sectional area within the sweetspot area showing a stiffened area of changed fibre angles and/or type. FIG. 6.3 shows a longitudinal cross-section of a double wall polymer composite bat in accordance with the present invention with an alternative construction showing a thickened barrel wall 21 within the insert resulting in increased radial stiffness generally confirmed to the sweetspot areas of the barrel portion. FIG. 6.3A shows a cross-sectional area of a barrel location not within the sweetspot area. FIG. 6.3B shows a cross-sectional area within the sweetspot area showing a stiffened area with thicker barrel wall. FIG. 7 shows a longitudinal cross-section of a fourth embodiment of the present invention showing a double-wall tubular bat with two separate members, a frame or main member with an internal insert as a secondary member full length in the barrel portion, and in accordance with the present invention, showing an internal stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 7A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 7B shows a cross-sectional area within the sweetspot area showing the internal stiffener. FIG. 8 shows a longitudinal cross-section of a fifth embodiment of the present invention showing a double-wall tubular bat with two separate members, a frame or main member with an external sleeve as a secondary member full length in the barrel portion, and in accordance with the present invention showing an external stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 8A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 8B shows a cross-sectional area within the sweetspot area showing the external stiffener. FIG. 9 shows in graphical form the typical relationship between tubular bat performance and barrel location and sweetspot size. FIG. 10 shows in graphical form a typical relationship between tubular bat performance of a bat of the present invention and barrel location and sweetspot size. FIG. 11A shows a longitudinal cross-section of the barrel portion of a typical prior art single wall tubular bat with a singular frame, or main member. Not shown in FIG. 11A and all following figures is the traditional bat handle portion located at the proximal end of the taper portion. FIG. 11B shows a longitudinal cross-section of the barrel portion of a typical prior art single wall tubular bat with a singular frame, or main member, construction wherein the barrel wall is inwardly thickened generally in the area of the sweetspot. FIG. 11C shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert. FIG. 11D shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert, wherein the insert is inwardly thickened generally in the area of the sweetspot. FIG. 11E shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert, wherein both the frame and the insert are inwardly thickened generally in the area of the sweetspot. FIG. 12A shows a longitudinal cross-section of the barrel portion of one embodiment of the present invention showing a double wall tubular bat with an external frame and a primary secondary member, or insert, located internally within the frame wherein the primary secondary member has an outer diameter which varies along the length of the member, a constant wall thickness, two contact regions with the frame barrel portion inner surface, and one air cavity that is closed at both ends. FIG. 12B shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness, there are two contact regions, and one closed air cavity, wherein the thickness of the air cavity is reduced generally in the area of the barrel mid portion. FIG. 12C shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness, there are three contact regions and two closed air cavities. FIG. 12D shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness and the outer diameter of the primary secondary member oscillates periodically along its length between a maximum and a minimum diameter, creating multiple contact regions and multiple closed air cavities. FIG. 12E shows a variant of the bat of FIG. 12D wherein the period of the oscillation of outside diameter of the primary secondary member increases away from the barrel mid portion. FIG. 12F shows a variant of the bat of FIG. 12A with a primary secondary member and an additional secondary member located internally to the primary secondary member wherein both secondary members have outer diameters which vary along the length of the secondary members, have constant wall thicknesses, two contact regions each, and one closed air cavity each. FIG. 12G shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant diameter internal surface, a non-constant diameter external surface, a non-constant wall thickness, two contact regions with the internal frame wall, and one air cavity that is closed at both ends. FIG. 12H shows a variant of the bat of FIG. 12G wherein the primary secondary member has two contact regions and one closed air cavity that has a non-uniform cross-section. FIG. 12I shows a variant of the bat of FIG. 12G wherein the primary secondary member has three contact regions and two closed air cavities. FIG. 12J shows a variant of the bat of FIG. 12D wherein the primary secondary member has a constant diameter internal surface. FIG. 12K shows a variant of the bat of FIG. 12E wherein the primary secondary member has a constant diameter internal surface. FIG. 12L shows a variant of the bat of FIG. 12F wherein the primary secondary member has a constant diameter internal surface. FIG. 13A shows a longitudinal cross-section of the barrel portion of a second embodiment of the present invention showing a double wall tubular bat with an external frame, and six independent annular secondary members, or rings, each of length less than one-half the frame barrel portion length and varying thickness, each internally located side by side, with or without spaces between, along the frame barrel portion length against the barrel portion inner surface of the external bat frame. FIG. 13B shows a multi-wall bat variant of the bat of FIG. 13A wherein there are six independent annular secondary members each of length less than one-half the frame barrel portion length, each internally located along the frame inner wall surface, and a tubular additional secondary member with length approaching the frame barrel portion length and located internally to the annular secondary members and in contact with at least one annular secondary member, generally extending co-extensively with the frame barrel portion. FIG. 13C shows a variant of the bat of FIG. 13B wherein there are six independent annular secondary members each of length less than one-half the frame barrel portion length, each internally located along the additional secondary member outer wall surface and internally to the external frame inner wall surface. FIG. 13D shows a variant of the bat of FIG. 13B wherein there are three independent annular secondary members of constant thickness each internally located between and abutting against the external frame inner wall surface and the additional secondary member outer wall surface forming three closed air cavities. FIG. 13E shows a variant of the back of FIG. 13D wherein there are multiple annular secondary members with or without multiple air cavities. FIG. 13F shows a longitudinal cross-section of the barrel portion of another embodiment of the present invention showing a multi-wall tubular bat with an external frame, and two annular secondary members, or rings, each of length less than one-half the frame barrel portion length, wherein each annular secondary member is located between the outer frame and an additional secondary member with length approaching the frame barrel portion length, wherein the wall of the additional secondary member is thickest generally in the frame barrel mid portion providing a contact area between the inner surface of the frame and the outer surface of the additional secondary member. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to providing tubular baseball bats with variable radial stiffness along the length of the barrel or hitting portion 1 , of the bats. Bats of the present invention can have a larger sweetspot size 19 , have a soft feel with substantially reduced vibrations, and produce unique pleasing sounds upon impact with a baseball or softball. Further, such bats can be produced at reasonably low costs. Unless otherwise indicated, the term stiffness as used in this disclosure is equivalent to the modulus of elasticity and is a measure of the change in length of a material under loading. For a tubular body, such as a baseball bat, stiffness of the material can be measured in the axial direction, parallel to the longitudinal axis of the tube, or the radial or transverse direction perpendicular to the longitudinal axis of the tube. Radial stiffness is a measure of the force required to depress any given a section of the tube in the radial direction. Radial stiffness is a function of modulus of the material, the tube thickness and the tube diameter. Radial stiffness is measured along the barrel wall as independent annular segments of the barrel wall at each measurement location. The prior art bats are shown in FIGS. 1 , 2 , 3 , and 11 . FIGS. 1 and 11A show a single wall tubular bat with main member or frame 16 . FIGS. 2 and 11C show a double wall tubular bat with an insert or primary secondary member 13 , formed separately from the main member 16 , which is fitted into the entire barrel length 1 of the main member 16 . FIG. 3 shows a double wall tubular bat with a sleeve 14 , formed separately from the main member 16 , which is fitted over the entire barrel length 1 of the main member 16 . FIG. 11B shows a single wall tubular bat with the main member 16 being internally thickened in the barrel mid-section. FIGS. 11D and 11E show double wall tubular bats with an internally thickened secondary member 13 and in the case of FIG. 11E also an internally thickened main member 16 . Though not indicated in FIGS. 1 through 8 , and 11 through 14 , bats of the present invention, similarly to bats of the prior art, include a traditional knob at the handle portion end 5 , or proximal end of the bat, and a traditional end cap 21 (not shown in FIGS. 1 through 8 ) at the barrel portion end 4 , the distal end, both of which can be made from a variety of materials. Most adult tubular baseball bats of the prior art have maximum outside barrel portion diameter 2 of either 2.625 inches or 2.75 inches. Depending on the taper portion geometry of the mid-section 8 , and the total length of the bat, the barrel length 1 as defined by length of constant maximum diameter 2 , ranges from 4 to 12 inches. Total barrel wall thickness 6 ranges from 0.100 inches to 0.140 inches for aluminum bats and up to 0.220 inches for all composite bats and is measured at any point along the barrel wall as the outside diameter of the frame or member with the largest outside diameter minus the inside diameter of the member with the smallest outside diameter including any gaps, or spaces, between the two extreme diameters. Most youth baseball bats and softball bats of the prior art have maximum outside barrel portion diameter 2 of 2.25 inches. Depending on the taper portion geometry of the mid-section 8 , the barrel length 1 ranges from 4 to 16 inches. Barrel wall thickness 6 ranges from 0.060 inches to 0.090 inches for aluminum bats and up to 0.220 inches for all composite bats. The bats of the present invention, shown in FIGS. 4 through 8 , and 12 through 14 , have similar dimensions to the foregoing prior art bats shown in FIGS. 1 , 2 , 3 , and 11 . A first embodiment of the present invention FIG. 4 is a single wall tubular baseball bat consisting of a cylindrical handle portion 7 for gripping, a cylindrical tubular barrel portion 9 for striking or hitting, and a tapered portion 8 connecting the handle 7 and barrel 9 portions, with a thin polymer composite stiffener 18 having a stiffener wall located internally within the barrel portion 9 and extending longitudinally in the mid-section, sweetspot area 19 of the barrel length 1 . A polymer composite is a non-homogenous material consisting of continuous fibers embedded in, and wetted by, a polymeric resin matrix whereby the properties of the material are superior to those of its constituent fibers and resin taken separately. Such polymer composites are anistropic materials since they exhibit different responses to stresses applied in different directions depending on how the fibers are aligned or angled within the matrix. Other materials commonly used in bat constructions such as aluminum, wood and plastics are not anistropic and are thus limited in controlling bat performance; for example, radial stiffness is equal to longitudinal stiffness and cannot be graduated along the barrel length 1 . However, with composite materials, which are preferred, properties of bats made in accordance with the present invention, such as radial stiffness which determines bat performance can be controlled (i.e. designed to a given requirement) by altering such parameters as the fiber alignments along the barrel length 1 , and/or the type of fibers chosen, their demier or layout density and/or the thickness of the polymer composite structure. Generally, the fiber materials used are selected from a group consisting of fiberglass, graphite or carbon, aramid, boron, nylon, or hybrids of any of the foregoing, all of which are commercially available. The resins used to impregnate, wet out, and encapsulate or imbed the fiber materials are generally selected from a group consisting of epoxy, polyester, vinyl ester, urethane, or a thermoplastic such as nylon, or mixtures thereof. The first embodiment of the present invention, depicted in FIG. 4 , consists of a thin polymer composite stiffener 18 located internally within the barrel portion 9 generally in the sweetspot area 19 located in proximity to the middle or mid-section area of the barrel length 1 of a single wall tubular bat. The resultant stiffened bat results in a predetermined calculated lower performance, with an enlarged sweetspot 19 , as subsequently explained. The sweetspot area 19 of a baseball bat is generally referred to as that area along the barrel length 1 in which bat performance is greatest; that is, a ball struck within the sweetspot area 19 will travel further than a ball struck on either side of the sweetspot area. Typically, the sweetspot area 19 is located around the middle of the barrel length 1 and is in the order of about 2 inches to 4 inches in length when compared to overall barrel lengths 1 which range from approximately 4 inches to 16 inches or more. In actual practice, the performance of a baseball bat of the prior art follows a statistical normal distribution along the barrel length 1 , usually centered near the middle of the barrel length 1 in the sweetspot area 19 . FIG. 9 shows a typical bat performance distribution example with a 12-inch barrel length 1 . In FIG. 9 , the maximum bbs (one measure of bat performance standard) is 100 while most players would describe the sweetspot as being approximately 2 inch long (that is, the portion of the barrel length equal to or greater than 98 bbs). The bat of this particular sample meets a bat performance factor standard of 100 bbs maximum if so regulated. If the applicable regulatory body for the bat in the FIG. 9 example changed the bat performance standard from 100 bbs maximum to say 96 bbs maximum, the bat of the present invention could be provided with a specifically designed 4 inch polymer composite stiffener 18 located in the center of the barrel length 1 . FIG. 10 shows the bbs versus barrel length for this example. In FIG. 10 , in an example of the present invention, the combined barrel wall, with the polymer composite stiffener 18 present, is approximately twice as stiff in the center 2 inches of the sweetspot area 19 as in the 1 inch area immediately adjacent to the center or mid-section area on each side of the center area. The polymer composite stiffener 18 fiber type, fiber angles and thicknesses are designed such as to reduce the bbs from 100 to 96 in the center 2 inch area of the barrel length 1 and from 98 to 96 bbs in the 1 inch areas immediately adjacent to the center area. As a result of the present invention, the resultant typical example bat meets the lowered regulatory standard of 96 bbs with a sweetspot area 19 which has been increased in size by 100% (from 2 inches wide to 4 inches wide). At the same time the regions around points A and B have been introduced into the batting performance curve of FIG. 10 that were not present in the curve of FIG. 9 , with the more flattened portion there-between that is characteristic of an enlarged sweet spot. Alternatively, thickening the total barrel wall with the same material, the same thickness, and the same location as the stiffener results in the identical reduced bat performance. The first embodiment (i.e. as shown in FIG. 4 ) of the present invention is particularly suited to retrofitting used bats returned by players and making them legally playable under a revised standard. The thin polymer composite stiffener 18 of the present invention has a stiffener wall which is typically in the order of 0.010 inches to 0.040 inches in thickness, preferably 0.020″ with a length of 2 inches to 6 inches which is typically less than 50% of the barrel length, such as 16⅔% of the barrel length, as is apparent from FIG. 10 . A 4 inch stiffener, in a 12 inch barrel as referenced in FIG. 10 , would represent 33.3% of the barrel length; a 4 inch stiffener in a 16 inch barrel would represent 25%, and a 2 inch stiffener in a 16 inch barrel would represent 12.5% of the barrel length. The stiffener 18 is preferably bonded, fully or partially, to the main member 16 , or to the secondary member insert 13 of FIG. 7 or to the secondary member sleeve 14 of FIG. 8 , or combinations thereof on either the internal or external barrel walls, as shown in FIGS. 4 , 5 , 7 and 8 . Analogous to FIGS. 4 , 5 , 7 and 8 an alternative solution (since stiffness is proportional to thickness) to the stiffener 18 is to vary the barrel thickness 6 to the same extent and manner along any portion of the barrel length 1 of any bat according to the invention, including the bat of FIG. 6 in order to vary bat performance. The barrel portion's effective wall thickness in the mid-section can be greater by 8⅓% or more over the thickness of the barrel in the lateral, adjacent portions. Conversely, the barrel wall's thickness beyond its central portion, in the lateral regions proceeding towards the end portions of the barrel, may be at least 8⅓% thinner than the thickness of the barrel wall in the mid-section. Just as the stiffener wall may be typically in the order of 0.005 inches to 0.040 inches in thickness, or 0.010 inches to 0.040 inches in thickness, or 0.015 inches to 0.040 inches in thickness, or 0.015 inches to 0.030 inches, so too the analogous increase in barrel wall thickness along the mid-section may fall within the same ranges. A second embodiment of the present invention, as shown in FIG. 5 , is a single wall tubular baseball bat which in accordance with the present invention has a thin polymer composite stiffener 18 located externally to the barrel portion 9 generally in the sweetspot area 19 located in proximity to the middle area of the barrel length 1 . The resultant stiffened bat results in a calculated lower performance, with a bigger (longer) sweetspot 19 , as previously explained. A third embodiment of the present invention, as shown in FIG. 6 , is a single wall tubular polymer composite baseball bat which in accordance with the present invention has a localized area of fiber type of greater stiffness and/or angle change 20 resulting in increased radial stiffness generally in the sweetspot area 19 located in proximity to the middle area of the barrel length 1 . This embodiment applies equally well to double-wall and multi-wall (more than two walls) tubular all polymer composite baseball bats and is limited to newly designed polymer composite single wall, double-wall, and multi-walled new bats as opposed to field returned bats. The fiber types, and/or fiber angles, and/or fiber sizes, and/or composite thickness can be designed such as to graduate the radial stiffness of the barrel wall within the barrel portion 1 along its entire length. That is, the radial stiffness could be higher in the peak performance area (generally the sweetspot area 19 ) than in the lateral regions immediately adjacent to the sweetspot area 19 . In fact, by duplicating the increase in radial stiffness in the barrel mid-section as achieved by the stiffener 18 of FIG. 4 or 7 , the exact same bat performance change as shown in FIG. 10 and enlarged in sweetspot size 19 can be achieved by bats of FIG. 6 . Similarly, the alternative solution FIG. 6.1 showing a single wall tubular bat with a thickened barrel wall 21 and the alternative solution FIG. 6.3 showing a double wall tubular bat with a thickened barrel wall 21 , with the same material, location, and thickness of the stiffener 18 will result in the same bat performance change, as shown in FIG. 10 , and resultant enlarged sweetspot size 19 . A fourth embodiment of the present invention, as shown in FIG. 7 , is a double-wall tubular bat showing two separate members, a frame or main member 16 with an internal insert 13 as a secondary member full length in the barrel length 1 and, in accordance with the present invention, a stiffener 18 located internally within the insert 13 generally confined to the sweetspot area 19 , along the barrel length 1 . Though not shown, the stiffener 18 could be located externally to the main member 16 or between the main member 16 and the internal insert 13 . Also, though not shown, in multi-walled bats the stiffener 18 could be located internally, or externally, or between the members, or combinations thereof. A fifth embodiment of the present invention, as shown in FIG. 8 , is a double-wall tubular bat showing two separate members, a frame or main member 16 with an external sleeve 14 as a secondary member full length in the barrel length 1 and, in accordance with the present invention, a stiffener 18 , located externally to the sleeve 14 , generally in the area of the sweetspot area 19 along the barrel length 1 . Though not shown, the stiffener 18 could be located internally to the main member 16 and the external sleeve 14 . Also, though not shown, in multi-walled bats, the stiffener 18 could be located internally, or externally, or between the members, or combinations thereof. All embodiments of the present invention, as shown in FIGS. 4 , 5 , 6 , 7 , 8 , 12 C, 12 I, 13 A, 13 B, 13 C, 13 D, and 13 F, exhibit greater radial stiffness in the mid-section of the barrel length 1 relative to the lateral regions immediately adjacent to the mid-section, resulting in an enlarged sweetspot area 19 . Besides an enlarged sweetspot, other objectives of bats of the present invention include providing a user with a “soft feel”, having substantially less vibrations transmitted to the user's hand while striking a ball, unique impact sounds, and higher performance for average or below average players when making contact away from the normal sweetspot. These further objectives are achieved by bats of the present invention with secondary members with a variable outside diameter and by bats with two or more independent annular secondary members internally located along the inside diameter of the external bat frame. All bats of the present invention shown in FIG. 12 are characterized by inventive primary secondary members, or inserts 13 , located internally within an external main member, or frame 16 , with frame wall thickness 44 , within the barrel length 1 of the hitting portion of the bat. The primary secondary member 13 has an inner surface 53 , an outer surface 55 , an inner diameter 29 , an outer diameter 25 , a wall thickness 27 , a length 26 , a proximal end 58 , and a distal end 59 . Not shown in the FIGS. 12 and 13 bats is the normal handle portion located adjacent to the taper proximal portion and knob located at the proximal end of the frame 16 traditional bats. A traditional endcap 21 encloses the distal end 49 of the barrel portion 9 . The inventive primary secondary members 13 of the bats of FIG. 12 have outer diameters 25 that vary along the majority of the barrel length 1 . The variations in outer diameter 25 of the inserts 13 in all bats of FIGS. 12 are dimensioned to produce two or more contact areas 30 with the inside surface 45 of the frame 16 . In some variants of the bats of FIG. 12 , the primary secondary member 13 contact areas 30 have substantially flattened portions of constant maximum outer diameter, while in others the contact portions are much smaller. The contact areas 30 create at least one enclosed air cavity 22 with a maximum air cavity thickness 23 of at least 0.010″. The air cavities 22 of the present invention are closed at both ends to produce the desired feel and sound objectives upon ball contact. Varying positioning and quantities of the air cavities 22 , and contact areas 30 , produce bats with different performance levels, feel, and sound upon barrel portion 9 impact with a ball. To produce the desired unique soft bat feel and sound upon impact, the ideal thickness 23 of the air cavities 22 has been found by field testing to be 0.020″ to 0.050″ which is considerably thicker than prior art bats, where any such air spaces exist only due to manufacturing tolerances of the frame 16 and secondary member 13 . The air cavities 22 of the present invention can be filled with an elastomeric material with further performance, feel, and sound effects. Such prior art secondary members 13 do not have variable outer diameters. Due to the variable outer diameter 25 , all bats of FIG. 12 can have variable radial stiffness along the barrel length 1 . However, when the frame 16 and/or the primary secondary member 13 is made with composite materials, fiber types and laminating angles can be manipulated to achieve either constant or variable radial stiffness along the barrel length 1 regardless of dimensional variations. As seen in FIGS. 12A through 12F bats of the present invention are further characterized by the inventive primary secondary member 13 having a variable outer diameter 25 and a variable inner diameter 29 . The variable outer diameter 25 of the insert 13 produces variations in the surface profile of the insert 13 which are generally reflected by a corresponding profile on the inner surface 53 of the insert 13 wall. The resulting total bat wall thickness 6 variations along the barrel length 1 vary the performance, feel, and sound of the bats of FIGS. 12A through 12F . The bat variant of FIG. 12A has a single annular air cavity 22 where the external frame 16 wall acts independently of the insert 13 wall until the contact force between the ball and the external frame 16 increases enough to deflect the external frame inner surface 45 into contact with the insert's outer surface 55 . At that point, the two members 16 and 13 act together, thus creating a non-linear spring. This decreases the peak contact force between the ball and the bat, which reduces the energy losses in the ball, and therefore improves performance. The bat variant of FIG. 12B has an insert 13 outside diameter 25 which increases near the barrel mid-portion 50 , narrowing the air cavity 22 thickness. This reduces the performance improvement due to the effect of the gap, discussed in the previous paragraph, near the mid-portion 50 of the barrel length 1 and therefore gives a more uniform bat performance along the barrel length 1 . The bat variant of FIG. 12C is similar to 12 B where the insert 13 makes contact with the frame 16 inner surface 45 near the mid-portion 50 of the barrel length 1 at the insert 13 proximal 58 and distal 59 portions near the barrel ends. This eliminates the performance improvement imparted on the bat by the air cavity 22 at the barrel mid-portion 50 , but creates two independent annular air cavities 22 away from the barrel mid-portion 50 . The bat variant of FIG. 12D has an insert 13 where the outside diameter 25 oscillates, or varies periodically along the barrel length 1 . When the period of the oscillations is reduced the insert 13 becomes stiffer and stronger for a given weight, or lighter for a given stiffness. The radial stiffness of the insert 13 increases with increased insert wall thickness 27 , reduced period of oscillation, or increased magnitude of oscillation. The bat variant of FIG. 12E has an insert 13 where the outside diameter 25 oscillates, or varies periodically along the barrel length 1 , and where the period of the oscillation increases away from the mid-portion 50 of the barrel length 1 . The resultant reduced radial stiffness away from the sweetspot creates a more uniform performance along the barrel length 1 . The bat variant of FIG. 12F is a triple wall version of the bat of FIG. 12A created by an additional secondary member 31 . Though not shown, additional such members could be added to create a multi-wall bat with more than three walls. Similarly, though not shown, additional secondary members 31 of any configuration could be added to the bats of FIGS. 12B , 12 C, 12 D, and 12 E. FIGS. 12G through 12L depict bats characterized by an inventive primary secondary member 13 with a variable outer diameter 25 and a constant inner diameter 29 along the barrel length 1 . Otherwise, the bat variants of FIGS. 12G through L are similar to the bat variants of FIGS. 12A through F. In another embodiment of the present invention, the bats of FIG. 13 have two or more independent annular, or ring-like, secondary members 61 of similar cross-section shape of variable dimensions with individual length 62 , along the barrel portion 19 , less than one-half the barrel portion length 1 and are internally located along the inner surface 45 of the external frame 16 . The annular secondary members 61 have a length 62 , a wall thickness 63 , an inner surface 64 , an inner diameter 65 , an outer surface 66 , and an outer diameter 67 . The bat variant of FIG. 13A has the external frame 16 reinforced by a series of independent inner annular secondary members 61 generally in the form of annular rings. The secondary members 61 have a common outer diameter 67 which is equal to or less than the inner diameter 25 of the frame 16 and are generally thicker near the barrel mid-portion 50 of the barrel length 1 and thinner away from it. The rings 61 are generally thicker towards the barrel distal end 49 and thinner towards the barrel proximal end 48 because the bat is moving faster at the distal end 49 . Although not shown, the annular secondary members 61 could be of constant thickness and have varying material properties to accomplish varying radial stiffness and resultant more uniform performance. The bat variant of FIG. 13B has an external frame 16 reinforced by a series of independent annular secondary members 61 in the form of annular rings, in combination with an inner additional secondary continuous member 31 extending along the majority of the barrel length 1 . The annular secondary members 61 provide a more uniform bat performance along the barrel length, while the inner additional secondary member 31 supports the impact force. The bat variant of FIG. 13C is similar to that of 13 B; however, the annular secondary members 61 have a constant inner diameter 29 . The bat variant of FIG. 13D has internal annular secondary members 61 with a uniform inner diameter 29 and outer diameter 25 , which create closed air cavities 22 . The bat variant of FIG. 13E has an external frame 16 and axially continuous inner additional secondary member 31 with a series of annular secondary members 61 between the two. One candidate for the intermediate members 61 is a series of elastomeric O-rings with higher stiffness near the barrel mid portion 50 . The bat variant of FIG. 13F has an axially continuous inner additional secondary member 31 that is thicker in its mid-portion and could, or could not be, in contact with the external frame 16 near the barrel mid-portion 50 and has a reduced outer diameter at the barrel proximal 48 and distal 49 ends. The bat has two or more annular secondary members 61 located at the barrel portion 9 proximal 48 and diesel 49 ends. In effect, this bat is double walled at the barrel mid-portion 50 and triple walled away from the barrel mid-portion 50 , giving more uniform bat performance along the barrel length 1 resulting in a broadened sweetspot. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. CONCLUSION The foregoing has constituted a description of specific embodiments showing how the invention may be applied and put into use. These embodiments are only exemplary. The invention in its broadest, more specific aspects, is further described and defined in the claims which now follow. These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

A multi-walled, tubular baseball bat has a barrel portion with a mid-section wherein the radial stiffness of the overall barrel wall varies along the barrel length to provide an enlarged sweetspot, improved soft feel and performance, plus unique sounds upon impact. The bat has a frame with a barrel portion of consistent diameter. A secondary member, or members, of tubular form extend internally along the barrel. The secondary member provides the required radial stiffness variation by: 1) variations in the thickness of the wall of the secondary member or by, 2) secondary members with unique geometric external surface profiles or by, 3) the presence of functional air cavities, with or without closed ends, between the main bat frame and the secondary member or members or by, 4) the presence of numerous annular secondary members located side by side less than one-half the length of the barrel portion.

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60/986,191, filed on Nov. 7, 2007, the contents of which are herein incorporated by reference in their entirety for all purposes. STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT [0002] NOT APPLICABLE BACKGROUND OF THE INVENTION [0003] Homogeneous assay formats avoid the need for separation of an added detectably labeled specific binding partner is used. This type of methodology relies on devising a detection principle that is either turned on or turned off as a result of the binding reaction. In contrast, heterogeneous assays formats rely on physical separation of bound and free detectably labeled specific binding partners before quantitation. [0004] Homogeneous enzyme immunoassays generally exploit the antibody:antigen binding reaction to either activate or inhibit a label enzyme and may involve various methods of quenching fluorescence through antibodies or other fluorescent quenchers. Despite the considerable efforts made in devising homogeneous, or non-separation, assay formats, they still do not experience widespread commercial adoption. Heterogeneous assays are viewed as simpler to develop and mass-produce, even though they are operationally more complex. In particular, the field of high volume clinical immunodiagnostics and the smaller field of clinical nucleic acid diagnostics are dominated by heterogeneous assay formats. Within this arena, test formats would be beneficial to the field that could simplify protocols, reduce complexity and improve compatibility with automation by removing unnecessary steps. The present invention addresses these and other needs in the art. BRIEF SUMMARY OF THE INVENTION [0005] The present invention provides simple and efficient assay methods of detecting analytes. The assays presented herein may be performed for applications such as diagnostics and high through-put screening procedures. [0006] In one aspect, a novel method of detecting an analyte in a sample is provided. The method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder. The solid support conjugate is a solid support that is conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. The analyte is allowed to bind to the first analyte binder and the second analyte binder thereby forming a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal. [0007] In another aspect, a method of detecting an analyte in a sample is provided. The method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder and the first analyte binder is being bound to a competition analyte. The solid support conjugate is a solid support conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. The analyte and the first analyte binder conjugate are allowed to competitively bind to the second analyte binder. The binding of the first analyte binder conjugate to the second analyte binder forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal. [0008] In another aspect, a solid support conjugate is provided. The solid support conjugate includes a solid support conjugated to a chemiluminescent compound, a hydrogen peroxide generating enzyme, and an analyte binder. [0009] In another aspect, a kit for detecting an analyte in a sample is provided. The kit includes a first analyte binder conjugate that is conjugated to a peroxidase enzyme, and a solid support conjugate that is conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. 1 is a schematic representation of a chemiluminescent detection method including a solid support conjugate and a first analyte binder conjugate, a peroxide generating enzyme, a peroxide generating enzyme substrate, and a chemiluminescent compound. DETAILED DESCRIPTION OF THE INVENTION I. Definitions [0011] Generally, a “sample” represents a mixture containing or suspected of containing an analyte to be measured in an assay. Samples which can be typically used in the methods of the invention include bodily fluids such as blood, which can be anti-coagulated blood as is commonly found in collected blood specimens, plasma, urine, semen, saliva, cell cultures, tissue extracts and the like. Other types of samples include solvents, seawater, industrial water samples, food samples and environmental samples such as soil or water, plant materials, eukaryotes, bacteria, plasmids, viruses, fungi, and cells originated, from prokaryotes. [0012] An “analyte” is a substance in a sample to be detected in an assay. The analyte can be a protein, a peptide, an antibody, or a hapten to which an antibody that binds it can be made. The analyte can be a nucleotide or oligonucleotide which is bound by a complementary nucleic acid or oligonucleotide. Other types of analytes include, drugs such as steroids, hormones, proteins, glycoproteins, mucoproteins, nucleoproteins, phosphoproteins, drugs of abuse, vitamins, antibacterials, antifungals, antivirals, purines, antineoplastic agents, amphetamines, azepine compounds, nucleotides, and prostaglandins, as well as metabolites of any of these drugs, pesticides and metabolites of pesticides, and receptors. Analytes also include cells, viruses, bacteria and fungi. [0013] The term “specific binding” refers to binding between two molecules such as a ligand and a receptor and is characterized by the ability of a molecule (ligand) to associate with another specific molecule (receptor) in the presence of many other diverse molecules. Specific binding of a ligand to a receptor is also evidenced by reduced binding of a detectably labeled ligand to the receptor in the presence of excess of unlabeled ligand (i.e. a binding competition assay). [0014] The term “antibody” (Ab) refers to a polypeptide with a framework region from an immunoglobulin gene or fragments thereof that specifically binds and recognizes an antigen. The recognized immunoglobulin genes include the kappa, lambda, alpha, gamma, delta, epsilon, and mu constant region genes, as well as the myriad immunoglobulin variable region genes. Immunoglobulin light chains are classified as either kappa or lambda, whereas immunoglobulin heavy chains are classified as gamma, mu, alpha, delta, or epsilon. The immunoglobulin heavy chains define the immunoglobulin classes (isotypes), IgG, IgM, IgA, IgD and IgE, respectively. Typically, the antigen-binding region of an antibody will be most critical in specificity and affinity of binding. Antibodies can be polyclonal or monoclonal, derived from serum, a hybridoma or recombinantly cloned, and can also be chimeric, primatized, or humanized. [0015] An example of an immunoglobulin (antibody) structural unit includes a tetramer. Each tetramer is composed of two identical pairs of polypeptide chains, each pair having one “light” (about 25 kD) and one “heavy” chain (about 50-70 kD). Disulfide bonds connect the heavy chain and the light chain of each individual pair. Further, the two heavy chains of each binding pair are connected through a disulfide bond in the hinge region. Each heavy and light chain has two regions, a constant region and a variable region. The constant region of the heavy chain is identical in all antibodies of the same isotype, but differs in antibodies of different isotypes. The variable region located at the N-terminus of the heavy and the light chain includes about 100 to 110 or more amino acids and is primarily responsible for antigen recognition. The terms variable light chain (V L ) and variable heavy chain (V H ) refer to these light and heavy chains, respectively. [0016] Antibodies exist, for example as intact immunoglobulins or as a number of well-characterized fragments produced by digestion with various peptidases. Thus, for example, pepsin digests an antibody below the disulfide linkages in the hinge region to produce F(ab)′ 2 , a dimer of Fab, which itself is a light chain joined to V H —C H 1 by a disulfide bond. The F(ab)′ 2 may be reduced under mild conditions to break the disulfide linkage in the hinge region, thereby converting the F(ab)′ 2 dimer into a Fab monomer. The Fab monomer is essentially Fab with part of the hinge region (see Fundamental Immunology (Paul ed., 3d ed. 1993). While various antibody fragments are defined in terms of the digestion of an intact antibody, one of skill will appreciate that such fragments may be synthesized de novo either chemically or by using recombinant DNA methodology. Thus, the term antibody, as used herein, also includes antibody fragments either produced by the modification of whole antibodies, or those synthesized de novo using recombinant DNA methodologies (e.g., single chain Fv) or those identified using phage display libraries (see, e.g., McCafferty et al., Nature 348:552-554 (1990)). [0017] A “chemiluminescent compound” as used herein, refers to a monovalent chemiluminescent compound conjugated to a solid support, comprising a chemiluminescent moiety and a linking moiety. The terms “chemiluminescent group” and “chemiluminescent moiety” are used interchangeably as are the terms “linking moiety” and “linking group.” The chemiluminescent moiety may undergo a reaction with an activator resulting in the conversion of the chemiluminescent moiety into a higher or excited state of energy. Without being bound by any particular mechanistic theory, the excited state may directly emit light upon relaxation or may transfer excitation energy to an emissive energy acceptor, thereby returning to the ground state. After being excited the emissive energy acceptor may emit light. A class of compounds which by incorporation of a linking moiety could serve as a chemiluminescent compound include, but is not limited to, cyclic diacylhydrazides such as luminol and structurally related cyclic hydrazides including isoluminol, aminobutylethylisoluminol (ABET), aminohexylethylisoluminol (AHEI), 7-dimethylaminonaphthalene-1,2-dicarboxylic acid hydrazide, ring-substituted aminophthalhydrazides, anthracene-2,3-dicarboxylic acid hydrazides, phenanthrene-1,2-dicarboxylic acid hydrazides, pyrenedicarboxylic acid hydrazides, 5-hydroxyphthal-hydrazide, 6-hydroxyphthalhydrazide, as well as other phthalazinedione analogs disclosed in U.S. Pat. No. 5,420,275 to Masuya et al. and in U.S. Pat. No. 5,324,835 to Yamaguchi. Other examples for compounds that may serve as a chemiluminescent moiety of the chemiluminescent compound used in the present invention are xanthene dyes such as fluorescein, eosin, rhodamine dyes, or rhodol dyes, aromatic amines and heterocyclic amines, acridan esters, thioesters and sulfonamides, and acridan ketenedithioacetal compounds that are known in the art to produce chemiluminescence by reaction with peroxide and peroxidase. [0018] The term “alkyl,” by itself or as part of another substituent, means, unless otherwise stated, a straight or branched chain, or cyclic hydrocarbon radical, or combination thereof, which may be fully saturated, mono- or polyunsaturated and can include di- and multivalent radicals, having the number of carbon atoms designated (i.e. C 1 -C 10 means one to ten carbons). Examples of saturated hydrocarbon radicals include, but are not limited to, groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, homologs and isomers of, for example, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. An unsaturated alkyl group is one having one or more double bonds or triple bonds. Examples of unsaturated alkyl groups include, but are not limited to, vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl, 3-butynyl, and the higher homologs and isomers. The term “alkyl,” unless otherwise noted, is also meant to include those derivatives of alkyl defined in more detail below, such as “heteroalkyl.” Alkyl groups that are limited to hydrocarbon groups are termed “homoalkyl”. An alkoxy is an alkyl attached to the remainder of the molecule via an oxygen linker (—O—). [0019] The term “alkylene” by itself or as part of another substituent means a divalent radical derived from an alkyl, as exemplified, but not limited, by —CH 2 CH 2 CH 2 CH 2 —, and further includes those groups described below as “heteroalkylene.” Typically, an alkyl (or alkylene) group will have from 1 to 24 carbon atoms, with those groups having 10 or fewer carbon atoms being preferred in the present invention. A “lower alkyl” or “lower alkylene” is a shorter chain alkyl or alkylene group, generally having eight or fewer carbon atoms. [0020] The term “heteroalkyl,” by itself or in combination with another term, means, unless otherwise stated, a stable straight or branched chain, or cyclic hydrocarbon radical, or combinations thereof, consisting of at least one carbon atoms and at least one heteroatom selected from the group consisting of O, N, P, Si and S, and wherein the nitrogen and sulfur atoms may optionally be oxidized and the nitrogen heteroatom may optionally be quaternized. The heteroatom(s) O, N, P and S and Si may be placed at any interior position of the heteroalkyl group or at the position at which the alkyl group is attached to the remainder of the molecule. Examples include, but are not limited to, —CH 2 —CH 2 —O—CH 3 , —CH 2 —CH 2 —NH—CH 3 , —CH 2 —CH 2 —N(CH 3 )—CH 3 , —CH 2 —S—CH 2 —CH 3 , —CH 2 —CH 2 , —S(O)—CH 3 , —CH 2 —CH 2 —S(O) 2 —CH 3 , —CH═CH—O—CH 3 , —Si(CH 3 ) 3 , —CH 2 —CH═N—OCH 3 , —CH═CH—N(CH 3 )—CH 3 , O—CH 3 , —O—CH 2 —CH 3 , and —CN. Up to two heteroatoms may be consecutive, such as, for example, —CH 2 —NH—OCH 3 . Similarly, the term “heteroalkylene” by itself or as part of another substituent means a divalent radical derived from heteroalkyl, as exemplified, but not limited by, —CH 2 —CH 2 —S—CH 2 —CH 2 — and —CH 2 —S—CH 2 —CH 2 —NH—CH 2 —. For heteroalkylene groups, heteroatoms can also occupy either or both of the chain termini (e.g., alkyleneoxy, alkylenedioxy, alkyleneamino, alkylenediamino, and the like). Still further, for alkylene and heteroalkylene linking groups, no orientation of the linking group is implied by the direction in which the formula of the linking group is written. For example, the formula —C(O) 2 R′— represents both —C(O) 2 R′— and —R′C(O) 2 —. As described above, heteroalkyl groups, as used herein, include those groups that are attached to the remainder of the molecule through a heteroatom, such as —C(O)R′, —C(O)NR′, —NR′R″, —OR′, —SR′, and/or —SO 2 R′. Where “heteroalkyl” is recited, followed by recitations of specific heteroalkyl groups, such as —NR′R″ or the like, it will be understood that the terms heteroalkyl and —NR′R″ are not redundant or mutually exclusive. Rather, the specific heteroalkyl groups are recited to add clarity. Thus, the term “heteroalkyl” should not be interpreted herein as excluding specific heteroalkyl groups, such as —NR′R″ or the like. [0021] The terms “cycloalkyl” and “heterocycloalkyl” (also referred to herein as a “heterocyclic”), by themselves or in combination with other terms, represent, unless otherwise stated, cyclic versions of “alkyl” and “heteroalkyl”, respectively. Additionally, for heterocycloalkyl, a heteroatom can occupy the position at which the heterocycle is attached to the remainder of the molecule. Examples of cycloalkyl include, but are not limited to, cyclopentyl, cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, cycloheptyl, and the like. Examples of heterocycloalkyl include, but are not limited to, 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4-morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl, 1-piperazinyl, 2-piperazinyl, and the like. The terms “cycloalkylene” and “heterocycloalkylene” refer to the divalent derivatives of cycloalkyl and heterocycloalkyl, respectively. [0022] The terms “halo” or “halogen,” by themselves or as part of another substituent, mean, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom. Additionally, terms such as “haloalkyl,” are meant to include monohaloalkyl and polyhaloalkyl. For example, the term “halo(C 1 -C 4 )alkyl” is mean to include, but not be limited to, trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, and the like. [0023] The term “acyl” means —C(O)R where R is a substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl. [0024] The term “aryl” means, unless otherwise stated, a polyunsaturated, aromatic, substituent that can be a single ring or multiple rings (preferably from 1 to 3 rings), which are fused together or linked covalently. The term “heteroaryl” refers to aryl groups (or rings) that contain from one to four heteroatoms selected from N, O, and S, wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen atom(s) are optionally quaternized. A heteroaryl group can be attached to the remainder of the molecule through a heteroatom. Non-limiting examples of aryl and heteroaryl groups include phenyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl, 4-pyrimidyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl, 1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 3-quinolyl, and 6-quinolyl. Substituents for each of the above noted aryl and heteroaryl ring systems are selected from the group of acceptable substituents described below. The terms “arylene” and “heteroarylene” refer to the divalent radicals of aryl and heteroaryl, respectively. [0025] For brevity, the term “aryl” when used in combination with other terms (e.g., aryloxy, arylthioxy, arylalkyl) includes both aryl and heteroaryl rings as defined above. Thus, the term “arylalkyl” is meant to include those radicals in which an aryl group is attached to an alkyl group (e.g., benzyl, phenethyl, pyridylmethyl and the like) including those alkyl groups in which a carbon atom (e.g., a methylene group) has been replaced by, for example, an oxygen atom (e.g., phenoxymethyl, 2-pyridyloxymethyl, 3-(1-naphthyloxy)propyl, and the like). [0026] The term “oxo” as used herein means an oxygen that is double bonded to a carbon atom. [0027] The term “alkylsulfonyl” as used herein means a moiety having the formula —S(O 2 )—R′, where R′ is an alkyl group as defined above. R′ may have a specified number of carbons (e.g. “C 1 -C 4 alkylsulfonyl”). [0028] Each of the above terms (e.g., “alkyl,” “heteroalkyl,” “aryl” and “heteroaryl”) are meant to include both substituted and unsubstituted forms of the indicated radical. Preferred substituents for each type of radical are provided below. [0029] Substituents for the alkyl and heteroalkyl radicals (including those groups often referred to as alkylene, alkenyl, heteroalkylene, heteroalkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, and heterocycloalkenyl) are generically referred to as “alkyl group substituents,” and they can be one or more of a variety of groups selected from, but not limited to: —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′, -halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO 2 R′, —CONR′R″, —OC(O)NR′R″, —NR″C(O)R′, —NR″—C(O)NR″R′″, —NR″C(O) 2 R′, —NR—C(NR′R″R′″)═NR″″, —NR—C(NR′R″)═NR′″, —S(O)R′, —S(O) 2 R′, —S(O) 2 NR′R″, —NRSO 2 R′, —CN, — + NR 3 , — + PR 3 , —B(OH) 2 , and —NO 2 in a number ranging from zero to (2 m′+1), where m′ is the total number of carbon atoms in such radical. R′, R″, R′″ and R″″ each preferably independently refer to hydrogen, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, e.g., aryl substituted with 1-3 halogens, substituted or unsubstituted alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups. When a compound of the invention includes more than one R group, for example, each of the R groups is independently selected as are each R′, R″, R′″ and R″″ groups when more than one of these groups is present. When R′ and R″ are attached to the same nitrogen atom, they can be combined with the nitrogen atom to form a 5-, 6-, or 7-membered ring. For example, —NR′R″ is meant to include, but not be limited to, 1-pyrrolidinyl and 4-morpholinyl. From the above discussion of substituents, one of skill in the art will understand that the term “alkyl” is meant to include groups including carbon atoms bound to groups other than hydrogen groups, such as haloalkyl (e.g., —CF 3 and —CH 2 CF 3 ) and acyl (e.g., —C(O)CH 3 , —C(O)CF 3 , —C(O)CH 2 OCH 3 , and the like). [0030] Similar to the substituents described for the alkyl radical, substituents for the aryl and heteroaryl groups are generically referred to as “aryl group substituents.” The substituents are selected from, for example: halogen, —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′, -halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO 2 R′, —CONR′R″, —OC(O)NR′R″, —NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O) 2 R′, —NR—C(NR′R″R′″)═NR″″, —NR—C(NR′R″)═NR′″, —S(O)R′, —S(O) 2 R′, —S(O) 2 NR′R″, —NRSO 2 R′, —CN, — + NR 3 , — + PR 3 , —B(OH) 2 , and —NO 2 , —R′, —N 3 , —CH(Ph) 2 , fluoro(C 1 -C 4 )alkoxy, and fluoro(C 1 -C 4 )alkyl, in a number ranging from zero to the total number of open valences on the aromatic ring system; and where R′, R″, R′″ and R″″ are preferably independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl. When a compound of the invention includes more than one R group, for example, each of the R groups is independently selected as are each R′, R″, R′″ and R″″ groups when more than one of these groups is present. [0031] Two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula -T-C(O)—(CRR′) q —U—, wherein T and U are independently —NR—, —O—, —CRR′— or a single bond, and q is an integer of from 0 to 3. Alternatively, two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula -A-(CH 2 ) r —B—, wherein A and B are independently —CRR′—, —O—, —NR—, —S—, —S(O)—, —S(O) 2 —, —S(O) 2 NR′— or a single bond, and r is an integer of from 1 to 4. One of the single bonds of the new ring so formed may optionally be replaced with a double bond. Alternatively, two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula —(CRR′) s —X—(CR″R′″) d —, where s and d are independently integers of from 0 to 3, and X is —O—, —NR′—, —S—, —S(O)—, —S(O) 2 —, or —S(O) 2 NR′—. The substituents R, R′, R″ and R′″ are preferably independently selected from hydrogen or substituted or unsubstituted (C 1 -C 6 )alkyl. [0032] As used herein, the term “heteroatom” is meant to include oxygen (O), nitrogen (N), sulfur (S), silicon (Si) and phosphorus (P). [0033] A “substituent group,” as used herein, means a group selected from the following moieties: [0034] (A) —OH, —NH 2 , —SH, —CN, —CF 3 , —NO 2 , oxo, halogen, unsubstituted alkyl, unsubstituted heteroalkyl, unsubstituted cycloalkyl, unsubstituted heterocycloalkyl, unsubstituted aryl, unsubstituted heteroaryl, and [0035] (B) alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl, substituted with at least one substituent selected from: [0036] (i) oxo, —OH, —NH 2 , —SH, —CN, —CF 3 , — + NR 3 , — + PR 3 , —B(OH) 2 , —NO 2 , halogen, unsubstituted alkyl, unsubstituted heteroalkyl, unsubstituted cycloalkyl, unsubstituted heterocycloalkyl, unsubstituted aryl, unsubstituted heteroaryl, and [0037] (ii) alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl, substituted with at least one substituent selected from: [0038] (a) oxo, —OH, —NH 2 , —SH, —CN, —CF 3 , —NO 2 , halogen, unsubstituted alkyl, unsubstituted heteroalkyl, unsubstituted cycloalkyl, unsubstituted heterocycloalkyl, unsubstituted aryl, unsubstituted heteroaryl, and [0039] (b) alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, or heteroaryl, substituted with at least one substituent selected from oxo, —OH, —NH 2 , —SH, —CN, —CF 3 , —NO 2 , halogen, unsubstituted alkyl, unsubstituted heteroalkyl, unsubstituted cycloalkyl, unsubstituted heterocycloalkyl, unsubstituted aryl, and unsubstituted heteroaryl. [0040] As used herein, “amino acid” refers to a group of water-soluble compounds that possess both a carboxyl and an amino group attached to the same carbon atom. Amino acids can be represented by the general formula NH 2 —CHR—COOH where R may be hydrogen or an organic group, which may be nonpolar, basic acidic, or polar. As used herein, “amino acid” refers to both the amino acid radical and the non-radical free amino acid. [0041] The term “hydroxy” is used herein to refer to the group —OH. [0042] The term “amino” is used to describe primary amines, —NRR′, wherein R and R′ are independently H, alkyl, aryl or substituted analogues thereof “Amino” encompasses “alkylamino” denoting secondary and tertiary amines and “acylamino” describing the group RC(O)NR′. [0043] The term “alkoxy” is used herein to refer to the —OR group, where R is alkyl, aryl, or substituted analogues thereof. Suitable alkoxy radicals include, for example, methoxy, ethoxy, phenoxy, substituted phenoxy, benzyloxy, phenethyloxy, t-butoxy, etc. [0044] The term “acyloxy” is used herein to describe an organic radical derived from an organic acid by the removal of the acidic hydrogen. Simple acyloxy groups include, for example, acetoxy, and higher homologues derived from carboxylic acids such as ethanoic, propanoic, butanoic, etc. The acyloxy moiety may be oriented as either a forward or reverse ester (i.e. RC(O)OR′ or R′OC(O)R). [0045] A “ring,” as used herein, refers to a substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, and/or substituted or unsubstituted heteroaryl. [0046] As used herein, “nucleic acid” means either DNA, RNA, single-stranded, double-stranded, or more highly aggregated hybridization motifs, and any chemical modifications thereof. Modifications include, but are not limited to, those which provide other chemical groups that incorporate additional charge, polarizability, hydrogen bonding, electrostatic interaction, and functionality to the nucleic acid ligand bases or to the nucleic acid ligand as a whole. Such modifications include, but are not limited to, peptide nucleic acids, phosphodiester group modifications (e.g., phosphorothioates, methylphosphonates), 2′-position sugar modifications, 5-position pyrimidine modifications, 8-position purine modifications, modifications at exocyclic amines, substitution of 4-thiouridine, substitution of 5-bromo or 5-iodo-uracil; backbone modifications, methylations, unusual base-pairing combinations such as the isobases isocytidine and isoguanidine and the like. Modifications can also include 3′ and 5′ modifications such as capping. [0047] A “nucleobase” is a nucleoside or nucleotide. A “nucleoside” is a deoxyribose or ribose sugar, or derivative thereof, containing a nitrogenous base linked to the C1′ of the sugar residue. A “nucleotide” is the C5′ phosphate ester derivative of a nucleoside. The terms “nucleoside and “nucleotide” include those compounds having non-natural substituents at the C1′, C2′, C3′, C5′, and/or nitrogenous base (e.g., C2′ alkyl, alkoxy, and halogen substituents). [0048] “Polypeptide” refers to a polymer in which the monomers are amino acids and are joined together through amide bonds, alternatively referred to as a peptide. When the amino acids are α-amino acids, either the l-optical isomer or the d-optical isomer can be used. Additionally, unnatural amino acids, for example, β-alanine, phenylglycine and homoarginine are also included. Commonly encountered amino acids that are not gene-encoded may also be used in the present invention. All of the amino acids used in the present invention may be either the d- or 1-isomer. The 1-isomers are generally preferred. In addition, other peptidomimetics are also useful in the present invention. For a general review, see, Spatola, A. F., in Chemistry and Biochemistry of Amino Acids, Peptides and Proteins, B. Weinstein, eds., Marcel Dekker, New York, p. 267 (1983). II. Methods of Analyte Detection [0049] In one aspect, a novel method of detecting an analyte in a sample is provided. The method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder. The solid support conjugate is a solid support that is conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. The analyte is allowed to bind to the first analyte binder and the second analyte binder thereby forming a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal. In some embodiments, the detectable solid support bound analyte complex is also contacted with a peroxidase enhancer compound. [0050] Analytes that are detected using the methods provided herein include, cardiac markers and cardiac drugs such as Troponin I, CK-MB, digoxin, myoglobin and BNP. In other embodiments, the analyte is a drug and analyte related to reproductive function including AFP, DHEA-S, estradiol, FSH, LK, Inhibin A, PAPP-A, PIGF, sVEGF R1, progesterone, prolactin, SHBG, testosterone, βHCG, and unconjugated estriol. Other analytes include indicators of and drugs for treatment of anemia including EPO, ferritin, folate, Intrinsic Factor Ab, soluble transferrin receptor, and vitamin B12. Other analytes include intact PTH, bone alkaline phosphatase, and hGH for assessing bone metabolism. In some embodiments, analytes for assessing thyroid function include free and total T3, free and total T4, TSH, thyroglobulin, thyroglobulin Ab and TPO Ab. Other analytes include tumor markers AFP, BPHA, CA 15-3 antigen, CEA, CA 19-9 antigen, PSA, and CA 125 antigen. Infectious disease analytes include CMV IgG and IgM, Rubella IgG and IgM, Toxoplasmosis IgG and IgM, HAV Ab and IgM, HBc Ab and IgM, Hbe Ab and Antigen, HBs Ab and Antigen, and HCV Ab. [0051] Any appropriate peroxidase enzyme may be used in the methods provided herein. Peroxidase enzymes reduce hydrogen peroxide to water while oxidizing a variety of substrates. Exemplary peroxidase enzymes include a horseradish peroxidase enzyme, a peanut peroxidase enzyme, a barley grain peroxidase enzyme, an ascorbate peroxidase enzyme, a fungal peroxidase or a cytochrome-C peroxidase enzyme. In some embodiments, the peroxidase enzyme is a horseradish peroxidase. [0052] The choice of solid support for use in the present methods is based upon the desired assay format and performance characteristics. Acceptable solid supports for use in the present methods can vary widely. A solid support can be porous or nonporous. It can be continuous or non-continuous, and flexible or nonflexible. A solid support can be made of a variety of materials including ceramic, glass, metal, organic polymeric materials, or combinations thereof. Moreover, the solid support provided herein may be a magnetic solid support. The magnetic solid support may be composed at least in part of a magnetically responsive component such as a magnetic particle. Magnetic particles can have a solid core portion that is magnetically responsive and is surrounded by one or more non-magnetically responsive layers. Magnetically responsive components include magnetically responsive materials such as ferromagnetic, paramagnetic and superparamagnetic materials. One exemplary magnetically responsive material is magnetite. [0053] The solid support may further be coated with one or more coating particles. Such coating particles may function to provide reactive groups to conjugate the chemiluminescent moiety to the solid support. The chemiluminescent moiety may be connected to the solid support by reacting a reactive group of the linking moiety with a reactive group of the solid support. Reactive groups are further discussed below. In some embodiments, the coating particles may include BSA providing sulfhydryl, amino or carboxyl groups as reactive groups. In certain embodiments, the coating particles form at least part of a coating layer on the solid support. [0054] A peroxide-generating enzyme is an enzyme that catalyzes the oxidation or reduction reaction of a variety of substrates involving molecular oxygen as the electron acceptor. In such reactions oxygen is reduced to hydrogen peroxide or a combination of water and hydrogen peroxide. The generated hydrogen peroxide is then reduced to water by the peroxidase enzyme in the present reaction system. Examples of peroxide generating enzymes used in the embodiments presented include, but are not limited to, glucose oxidase, glycollate oxidase, hexose oxidase, cholesterol oxidase, aryl-alcohol oxidase, L-gulonolactone oxidase, galactose oxidase, pyranose oxidase, L-sorbose oxidase, pyridoxine oxidase, alcohol oxidase, L-2-hydroxy-acid oxidase, ecdysome oxidase, choline oxidase, aldehyde oxidase, xanthine oxidase, pyruvate oxidase, oxalate oxidase, glyoxylate oxidase, pyruvate oxidase, D-aspartate oxidase, L-aminoacid oxidase, amine oxidase, pyridoxaminephosphate oxidase, D-glutamate oxidase, ethanolamine oxidase, tyramine oxidase, putrascine oxidase, sarcosine oxidase, N-methylaminoacid oxidase, N-methyl-lysine oxidase, hydroxylnicotine oxidase, nitroethane oxidase, acetyl-indoxyl oxidase, urate oxidase, hydroxylamine oxidase, or sulphite oxidase. Any appropriate peroxide generating enzyme substrate may be used during the reduction or oxidation reaction catalyzed by the peroxidase generating enzyme. Examples for peroxide generating enzyme substrates are glucose, glycollate, hexose, cholesterol, aryl-alcohol, L-gulonolactone, galactose, pyranose, L-sorbose, pyridoxine, alcohol, L-2-hydroxy-acid, ecdysome, choline, aldehyde, xanthine, pyruvate, oxalate, glyoxylate, pyruvate, D-aspartate, L-aminoacid, amine, pyridoxaminephosphate, D-glutamate, ethanolamine, tyramine, putrascine, sarcosine, N-methylaminoacid, N-methyl-lysine, hydroxylnicotine, nitroethane, acetyl-indoxyl, urate, hydroxylamine, or sulphite. The reaction of a peroxide generating enzyme with a corresponding peroxide generating enzyme substrate results in oxidation or reduction of the peroxide generating enzyme substrate and production of hydrogen peroxide due to the reduction of oxygen. One of skill will immediately identify the corresponding substrates and enzymes listed above (e.g. the substrate for oxalate oxidase is oxalate). In some embodiments, glucose oxidase may be used as the peroxide generating enzyme to react with glucose as the peroxide generating enzyme substrate thereby reducing oxygen to hydrogen peroxide. Hydrogen peroxide may then be reduced to water by a peroxidase enzyme. Therefore, in some embodiments, the peroxide generating enzyme is glucose oxidase and the peroxide generating enzyme substrate is glucose. [0055] As described above, in some embodiments, the detectable solid support bound analyte complex is contacted with a peroxidase enhancer compound. Typically the peroxidase enhancer compound is present when the detectable solid support bound analyte complex is contacted with the peroxide generating enzyme substrate thereby producing peroxide. Without being limited by any particular mechanistic theory, it is believed that an oxidized peroxidase enhancer compound is generated from a peroxidase enhancer compound when the peroxidase enzyme reacts with hydrogen peroxide. The oxidized peroxidase enhancer compound may promote the catalytic activity of the peroxidase with a chemiluminescent compound during the process of generating luminescence. Thus, peroxidase enhancer compounds may be contacted with a detectable solid support bound analyte complex when the peroxide generating enzyme substrate is added. In the methods described herein, a peroxidase enhancer compound may include a phenolic moiety. In some embodiments, the peroxidase enhancer may be p-phenylphenol, p-iodophenol, p-bromophenol, p-hydroxycinnamic acid, p-imidazolylphenol, acetaminophen, 2,3,-dichlorophenol, 2-naphthol, or 6-bromo-2-naphthol or other art-known enhancers. Included among the enhancers for use herein are phenolic compounds and aromatic amines known to enhance other peroxidase reactions as described in U.S. Pat. Nos. 5,171,668 and 5,206,149. Substituted and unsubstituted arylboronic acid compounds and their ester and anhydride derivatives as disclosed in U.S. Pat. No. 5,512,451 are another class of compounds considered to be within the scope of enhancers useful in the present methods. Derivatives of phenoxazine and phenothiazine including 3-(N-phenothiazinyl)-propanesulfonic acid salts, 3-(N-phenoxazinyl)propanesulfonic acid salts, 4-(N-phenoxazinyl)butanesulfonic acid salts, 5-(N-phenoxazinyl)-pentanoic acid salts and N-methylphenoxazine and related homologs represent another useful group of enhancer compounds. [0056] The first analyte binder and the second analyte binder may be binding proteins such as, but not limited to, antibodies, antibody fragments, antibody-DNA chimeras, antigens, haptens, peptides, hormone receptors, protein A, lectin, avidin, streptavidin and biotin. In some embodiments, the first analyte binder and the second analyte binder are binding proteins. In other embodiment, the first analyte binder and the second analyte binder are antibodies. [0057] Again, without being limited by any particular mechanistic theory, it is believed that chemiluminescence is the emission of light as the result of a chemical reaction. In the presence of a suitable catalyst a chemiluminescent compound may be transferred into a higher state of energy due to the transfer of energy from a second reaction partner. The decay of the excited state of the chemiluminescent compound to a lower energy level may result in the emission of light. Upon relaxation to a ground state the chemiluminescent compound may either directly emit light or may transfer the excitation energy to an emissive energy acceptor, which is the source of light emission. The chemiluminescent compound useful herein typically comprises a chemiluminescent moiety, which may be transferred into a higher state of energy and a linking moiety for coupling to another material. The chemiluminescent moiety includes each class of compounds described above including, but not limited to, luminal and structurally related cyclic hydrazides, acridan esters, thioesters and sulfonamides, and acridan ketenedithioacetal compounds. In some embodiments, the chemiluminescent compound includes a chemiluminescent acridan moiety. Acridans represent compounds that react either directly or indirectly with a peroxidase enzyme and/or peroxide to produce a chemiluminescent signal. The following patents disclose chemiluminescent acridan moietie useful in the methods provided herein: U.S. Pat. Nos. 5,491,072, 5,523,212, 5,593,845, 5,750,698, 6,858,733, 6,872,828 and 7,247,726. [0058] During the process of hydrogen peroxide decomposition water and oxygen are produced either spontaneously or due to the presence of a decomposition agent. Decomposition agents catalyze the decomposition of peroxide to water and oxygen thereby removing excess peroxide from the reaction. Thus, background signal is reduced during analysis involving use of peroxidase conjugated analyte binders. The detectable solid support bound analyte complex may contacted with a peroxide decomposition agent for background signal reducing purposes. Therefore, in some embodiments, the detectable solid support bound analyte complex is contacted with a peroxide decomposition agent. In other embodiments, the detectable solid support bound analyte complex is contacted with the peroxide decomposition agent before being contacted with the peroxide generating enzyme substrate and the production of peroxide. The decomposition agents provided herein may be aromatic hydrocarbons or their derivatives. The decomposition agent may also be an enzyme that is able to react with hydrogen peroxide to produce water and oxygen. In some embodiments, the decomposition agent is an enzyme. In other embodiments, the decomposition agent is a catalase. In some embodiments, the catalase is present with the detectable solid support bound analyte complex at concentrations between 0.1 to 10 μg/ml. In other embodiments, the catalase is present with the detectable solid support bound analyte complex at concentrations between 0.5 to 5 μg/ml. In other embodiments, the catalase is present with the detectable solid support bound analyte complex at a concentration of about 2 μg/ml (e.g. 2 μg/ml). The catalase enzyme may be derived from prokaryotic or eukaryotic cells. In some examples, catalase enzymes are derived from human erythrocytes. Further, the catalase enzyme may be derived from murine, bovine or bison liver. [0059] It is sometimes desirable to detect an analyte in a sample using competition binding assays. During such competition binding assays the first or second analyte binder (which is conjugated to a solid support conjugate) interacts with a competition analyte. A competition analyte is a binding partner able to interact with the first or second analyte binder. The term competition analyte refers to, but is not limited to, a binding partner such as a protein, peptide or antibody that is able to interact with the first or second analyte binder. Among other things, the competition analyte may be a carbohydrate, peptide, protein, nucleic acid or drug (e.g. a hormone, cytokine, enzyme substrate, viruses, biomolecules, or small molecule modulator). In some embodiments, the competition analyte is a purified form of an analyte found in nature or a synthetic version of the analyte (e.g. an analyte produced chemically or using recombinant techniques). In other embodiments, the competition analyte is a competition analyte analog. A competition analyte analog is a binding partner with properties that enable the competition analyte analog to compete with the analyte for interaction with the first or second analyte binder. Examples of competition analyte analogs are nucleic acid analogs such as peptide nucleic acid (PNA) or conjugated polymers with DNA-mimetic properties, nonnatural and natural peptide analogs, peptide mimetics that biologically mimic active determinants on hormones, cytokines, enzyme substrates, viruses or other bio-molecules, and small molecule modulators (such as those having high affinity to the ATP binding site of ATP-dependent enzymes). [0060] Subsequent to binding the first or second analyte binder, the competition analyte competes with the analyte for interaction with the second or first analyte binder, respectively. A detectable solid support bound analyte complex may be formed upon binding of the competition analyte to the first analyte binder and the second analyte binder. However, if the analyte is bound to either the first or the second analyte binder within this competition binding assay, a detectable solid support bound analyte complex may be prevented from forming. Therefore, in the competition binding assays presented herein, lower amounts of analyte result in a stronger chemiluminescent signal, whereas higher concentrations of analyte result in a weaker chemiluminescent signal. [0061] In one aspect, the method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder where the first analyte binder is bound to a competition analyte. The solid support conjugate includes a solid support conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. The binding of the first analyte binder conjugate, which includes the competition analyte, to the second analyte binder forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal insofar as the amount of analyte correlates inversely to the intensity of the chemiluminescent signal. Thus, detecting the chemiluminescent signal may include detecting a lower amount of chemiluminescent signal or absence of chemiluminescent signal. [0062] In another embodiment, the method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder. The solid support conjugate includes a solid support conjugated to a peroxide generating enzyme, a chemiluminescent compound and a second analyte binder where the second analyte binder is bound to a competition analyte. The binding of the first analyte binder conjugate to the solid support conjugate, which includes the competition analyte, forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal insofar as the amount of analyte correlates inversely to the intensity of the chemiluminescent signal. Thus, detecting the chemiluminescent signal may include detecting a lower amount of chemiluminescent signal or absence of chemiluminescent signal. [0063] In one aspect, the method includes contacting the analyte, or a sample including the analyte, with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated (e.g. covalently bound) to a competition analyte. The competition analyte may be directly conjugated to the peroxidase enzyme or linked through a bifunctional linker. The solid support conjugate includes a solid support conjugated to a peroxide generating enzyme, a chemiluminescent compound and a second analyte binder. The binding of the first analyte binder conjugate, which includes the competition analyte conjugated to the peroxidase enzyme, to the solid support conjugate forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal insofar as the amount of analyte correlates inversely to the intensity of the chemiluminescent signal. Thus, detecting the chemiluminescent signal may include detecting a lower amount of chemiluminescent signal or absence of chemiluminescent signal. [0064] In another aspect, the method includes contacting the analyte with a solid support conjugate and a first analyte binder conjugate. The first analyte binder conjugate is a peroxidase enzyme conjugated to a first analyte binder. The solid support conjugate includes a competition solid support conjugate which includes a solid support conjugated to a peroxide generating enzyme, a chemiluminescent compound, and a competition analyte that is covalently bound to the solid support. The competition analyte may be directly conjugated to the solid support or through a bifunctional linker. The binding of the first analyte binder conjugate to the competition solid support conjugate forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal insofar as the amount of analyte correlates inversely to the intensity of the chemiluminescent signal. Thus, detecting the chemiluminescent signal may include detecting a lower amount of chemiluminescent signal or absence of chemiluminescent signal. [0065] In another aspect, the method includes contacting the analyte with a solid support conjugate and an analyte-peroxidase conjugate. The analyte-peroxidase conjugate is a peroxidase enzyme conjugated to the analyte or a homolog of the analyte. The solid support conjugate includes a solid support conjugated to a peroxide generating enzyme, a chemiluminescent compound, and a first analyte binder that is covalently bound to the solid support. The first analyte binder may be directly conjugated to the solid support or through a bifunctional linker. The binding of the first analyte binder to the analyte-peroxidase conjugate forms a detectable solid support bound analyte complex. The detectable solid support bound analyte complex is contacted with a peroxide generating enzyme substrate thereby producing a peroxide. The peroxidase enzyme is allowed to react with the peroxide which results in the activation of the chemiluminescent compound and the production of a chemiluminescent signal. The analyte is detected by detecting the chemiluminescent signal insofar as the amount of analyte correlates inversely to the intensity of the chemiluminescent signal. Thus, detecting the chemiluminescent signal may include detecting a lower amount of chemiluminescent signal or absence of chemiluminescent signal. [0066] In one aspect, a solid support conjugate is provided and the solid support conjugate includes a solid support conjugated to a chemiluminescent compound, a hydrogen peroxide generating enzyme, and an analyte binder. In some embodiments, the analyte binder is an antibody. In other embodiments, the hydrogen peroxide generating enzyme is a glucose oxidase. In other embodiments, the chemiluminescent compound includes a chemiluminescent acridan moiety. In some embodiments, the chemiluminescent compound has the formula: [0000] [0067] R 1 and R 2 may independently be substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted aralkyl. R 3 is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl, alkoxyalkyl, carboxyalkyl or alkylsulfonic acid. R 3 is optionally joined with R 7 or R 8 to form a 5 or 6-membered ring. R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, aralkyl, alkenyl, alkynyl, alkoxy, aryloxy, halogen, amino, substituted amino, substituted or unsubstituted carboalkoxy, carboxamide, cyano, or sulfonate. Pairs of adjacent groups of R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 are optionally joined to form a carbocyclic or heterocyclic ring system. At least one of the groups of R 1 to R 11 includes a linking moiety. In one embodiment, each of R 4 to R 11 is H. [0068] R 1 and R 2 in the compound of formula I can be any organic group containing from 1 to about 50 non hydrogen atoms selected from C, N, O, S, P, Si and halogen atoms which allows light production. By the latter is meant that when a compound of formula I undergoes a reaction of set forth in the methods provided herein, an excited state product compound is produced and can involve the production of one or more chemiluminescent intermediates. The excited state product can emit the light directly or can transfer the excitation energy to a fluorescent acceptor through energy transfer causing light to be emitted from the fluorescent acceptor. In one embodiment R 1 and R 2 are selected from substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, and substituted or unsubstituted aralkyl groups of 1-20 carbon atoms. When R 1 or R 2 are substituted, it can be substituted with 1-3 groups selected from carbonyl groups, carboxyl groups, tri(C 1 -C 8 alkyl)silyl groups, a SO 3 − group, a OSO 3 −2 group, glycosyl groups, a PO 3 − group, a OPO 3 −2 group, halogen atoms, a hydroxyl group, a thiol group, amino groups, quaternary ammonium groups, and quaternary phosphonium groups. [0069] R 3 is an organic group containing from 1 to 50 non-hydrogen atoms selected from C, N, O, S, P, Si and halogen in addition to the necessary number of H atoms required to satisfy the valences of the atoms in the group. In one embodiment, R 3 contains from 1 to 20 non-hydrogen atoms. In another embodiment, the organic group is selected from the group consisting of alkyl, substituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, and substituted or unsubstituted aralkyl groups of 1 to 20 carbon atoms. In another embodiment, R 3 includes substituted or unsubstituted C 1 -C 4 alkyl groups, phenyl, substituted or unsubstituted benzyl groups, alkoxyalkyl, carboxyalkyl and alkylsulfonic acid groups. R 3 can be joined to either R 7 or R 8 to complete a 5 or 6-membered ring. In one embodiment, R 3 is substituted with a linking moiety. [0070] In the compounds of Formula (I), R 4 to R 11 each are independently H or a substituent which permits the excited state product to be produced and generally contain from 1 to 50 atoms selected from C, N, O, S, P, Si and halogens. Representative substituents which can be present include, without limitation, alkyl, substituted alkyl, aryl, substituted aryl, aralkyl, alkenyl, alkynyl, alkoxy, aryloxy, halogen, amino, substituted amino, carboxyl, carboalkoxy, carboxamide, cyano, and sulfonate groups. Pairs of adjacent groups, e.g., R 4 to R 5 or R 5 to R 6 , can be joined together to form a carbocyclic or heterocyclic ring system comprising at least one 5 or 6-membered ring which is fused to the ring to which the two groups are attached. Such fused heterocyclic rings can contain N, O or S atoms and can contain ring substituents other than H such as those mentioned above. One or more of the groups R 4 to R 11 can be a linking moiety. In one embodiment, R 4 to R 11 are selected from hydrogen, halogen and alkoxy groups such as methoxy, ethoxy, t-butoxy and the like. In another embodiment, a group of compounds has one of R 5 , R 6 , R 9 or R 10 as a halogen and the other of R 4 to R 11 are hydrogen atoms. [0071] Substituents can be incorporated in various quantities and at selected ring or chain positions in the acridan ring in order to modify the properties of the chemiluminescent compound or to provide for convenience of synthesis. Such properties include, e.g., chemiluminescence quantum yield, rate of reaction with the enzyme, maximum light intensity, duration of light emission, wavelength of light emission and solubility in the reaction medium. Specific substituents and their effects are illustrated in the specific examples below, which, however, are not to be considered limiting the scope of the invention in any way. For synthetic expediency compounds of formula I desirably have each of R 4 to R 11 as a hydrogen atom. [0072] In another embodiment, the chemiluminescent compound has the formula: [0000] [0073] In some embodiments, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , and R 11 are hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, a linking moiety (-L-), or a substituent comprising a linking moiety (-L-). At least one of R 1 to R 11 includes a linking moiety or is a linking moiety (-L-). The linking moiety (-L-) is a bond, the reaction product of two reactive groups, substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene. In some embodiment, R 1 and R 2 are not hydrogen. In other embodiments, R 1 or R 2 are -L- or comprise -L-. The groups R 1 , R 2 and R 3 are as defined above, in the compounds of Formula (I). In some embodiments, the compound of Formulas (I) or (II) have a linking moiety as a substituent on the R 1 or R 2 group. In some embodiments, the chemiluminescent moiety is an acridan kentenedithioacetal. [0074] The linking moiety connects the chemiluminescent moiety to the solid support. The linking moiety may be attached to the solid support through a covalent bond. The covalent bond may be formed by contacting a reactive group on a linking moiety precursor with a reactive group on a solid support precursor. The solid support precursor may include a spacer moiety with a reactive group in order to increase chemical accessibility to the linking moiety precursor reactive group. By reacting the reactive groups of the linking moiety precursor and the solid support precursor, the chemiluminescent moiety is connected to the solid support. Exemplary classes of reactions are those proceeding under relatively mild conditions. These include, but are not limited to nucleophilic substitutions (e.g., reactions of amines and alcohols with acyl halides, active esters), electrophilic substitutions (e.g., enamine reactions), and additions to carbon-carbon and carbon-heteroatom multiple bonds (e.g., Michael reaction, Diels-Alder addition). These and other useful reactions are discussed in, for example, March, Advanced Organic Chemistry, 3rd Ed., John Wiley & Sons, New York, 1985; Hermanson, Bioconjugate Techniques, Academic Press, San Diego, 1996; and Feeney et al., Modification of Proteins; Advances in Chemistry Series, Vol. 198, American Chemical Society, Washington, D.C., 1982. [0075] Useful reactive groups include, for example: (a) carboxyl groups and derivatives thereof including, but not limited to activated esters, e.g., N-hydroxysuccinimide esters, N-hydroxybenztriazole esters, acid halides, acyl imidazoles, thioesters, p-nitrophenyl esters, alkyl, alkenyl, alkynyl and aromatic esters, activating groups used in peptide synthesis and acid halides; (b) hydroxyl groups, which can be converted to esters, sulfonates, phosphoramidites, ethers, aldehydes, etc.; (c) haloalkyl groups, wherein the halide can be displaced with a nucleophilic group such as, for example, an amine, a carboxylate anion, thiol anion, carbanion, or an alkoxide ion, thereby resulting in the covalent attachment of a new group at the site of the halogen atom; (d) dienophile groups, which are capable of participating in Diels-Alder reactions such as, for example, maleimido groups; (e) aldehyde or ketone groups, allowing derivatization via formation of carbonyl derivatives, e g, imines, hydrazones, semicarbazones or oximes, or via such mechanisms as Grignard addition or alkyllithium addition; (f) sulfonyl halide groups for reaction with amines, for example, to form sulfonamides; (g) thiol groups, which can be converted to disulfides or reacted with acyl halides, for example; (h) amine or sulfhydryl groups, which can be, for example, acylated, alkylated or oxidized; (i) alkenes, which can undergo, for example, cycloadditions, acylation, Michael addition, etc; (j) epoxides, which can react with, for example, amines and hydroxyl compounds; and (k) phosphoramidites and other standard functional groups useful in nucleic acid synthesis. In an exemplary embodiment, the solid support precursor includes a reactive amine and the linking moiety precursor includes a reactive carboxyl group. The solid support precursor is then covalently bonded to the linking moiety precursor using any appropriate amide bond forming agent, such as those used in the art of peptide synthesis. [0076] The reactive groups can be chosen such that they do not participate in, or interfere with, the reactions necessary to assemble or utilize the chemiluminescent moiety. Alternatively, a reactive group can be protected from participating in the reaction by the presence of a protecting group. Those of skill in the art understand how to protect a particular functional group such that it does not interfere with a chosen set of reaction conditions. For examples of useful protecting groups, see, for example, Greene et al., Protective Groups in Organic Synthesis, John Wiley & Sons, New York, 1991. [0077] In some cases attachment will not involve covalent bond formation, but rather physical forces in which case the linking group remains unaltered. Physical forces imply attractive forces such as hydrogen bonding, electrostatic or ionic attraction, hydrophobic attraction such as base stacking, and specific affinity interactions such as biotin-streptavidin, antigen-antibody and nucleotide-nucleotide interactions. [0078] In addition to the reactive group the linking moiety precursor and or solid support precursor may further include a spacer. In some embodiments, the spacer is on one or both sides of the bond formed by the reaction of the reactive group. The spacer may be a substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene. In another related embodiment, the spacer is selected from C 1 -C 10 substituted or unsubstituted alkylene, 2 to 10 membered substituted or unsubstituted heteroalkylene, C 3 -C 8 substituted or unsubstituted cycloalkylene, and 3 to 8 membered substituted or unsubstituted heterocycloalkylene. The spacer can be further defined as a bond, an atom, divalent groups and polyvalent groups, a straight or branched chain of atoms some of which can be part of a ring structure. The straight or branched chain can be substituted or unsubstituted and can be an alkylene or a heteroalkylene. The substituent usually contains from 1 to about 50 non-hydrogen atoms, more usually from 1 to about 30 non-hydrogen atoms. Examples for atoms included in the chain are selected from, but not limited to C, O, N, S, P, Si, B, and Se atoms. In another embodiment atoms comprising the chain are selected from C, O, N, P and S atoms. The number of atoms other than carbon in the chain is normally from 0-10. Halogen atoms can be present as substituents on the chain or ring. [0079] In some embodiments, a linking moiety may conjugate a competition analyte to an analyte binder, which can be a first or a second analyte binder, or to a solid support. Such linking moiety is referred to herein as a bifunctional linker. The bifunctional linker includes reactive groups at the point of attachment contacting the competition analyte and reactive groups at the point of attachment contacting the solid support or the analyte binder. The reactive groups at either point of attachment of the bifunctional linker may be separated by a spacer as previously described. The reactive groups at both points of attachment of the bifunctional linker may react with the corresponding reactive groups of the competition analyte and the solid support or the competition analyte and the analyte binder. Thus, the competition analyte is conjugated to the solid support or the analyte binder. Any of the linking moieties and reactive groups previously described may be used to conjugate the competition analyte to the analyte binder or the solid support. [0080] Kit embodiments provide a convenient means for supplying necessary reagents of the invention, ancillary reagents, apparatuses, instructions and/or other components necessary to implement the invention. In one aspect, a kit for detecting an analyte in a sample is provided. [0081] The kit includes a first analyte binder conjugate that is conjugated to a peroxidase enzyme, and a solid support conjugate that is conjugated to a second analyte binder, a peroxide generating enzyme, and a chemiluminescent compound. In some embodiments, the kit includes a solution containing the peroxide generating enzyme substrate. The kit may include a peroxidase enhancer compound. In some embodiments, the peroxidase enhancer compound is p-phenylphenol, p-iodophenol, p-bromophenol, p-hydroxycinnamic acid, p-imidazolylphenol, acetaminophen, 2,3,-dichlorophenol, 2-naphthol, or 6-bromo-2-naphthol. In one embodiment, the chemiluminescent compound in the kit includes a chemiluminescent acridan moiety. In some embodiments, the chemiluminescent acridan moiety is a acridan ketenedithioacetal. The first analyte binder and the second analyte binder included in the kit may be antibodies. The kit may include a solution containing a peroxide decomposition agent. In some embodiments, the peroxide decomposition agent of the kit is a catalase. [0082] Other materials useful in the performance of the assays can also be included in the kit, including test tubes, transfer pipettes, and the like. The kit may also include written instructions for the use of one or more of the reagents described herein. The invention contemplates additional kits packaged to deliver, instruct and otherwise aid the practitioner in the use of the invention. These additional kits include those for the use of diagnostic embodiments of the invention, and their construction is well known by those of skill in the art provided with the reagents set forth herein. Detection [0083] Light emitted by the present method can be detected by any suitable known means such as a luminometer, x-ray film, high speed photographic film, a CCD camera, a scintillation counter, a chemical actinometer or visually. Each detection means has a different spectral sensitivity. The human eye is optimally sensitive to green light, CCD cameras display maximum sensitivity to red light, X-ray films with maximum response to either UV to blue light or green light are available. Choice of the detection device will be governed by the application and considerations of cost, convenience, and whether creation of a permanent record is required. In those embodiments where the time course of light emission is rapid, it is advantageous to perform the triggering reaction to produce the chemiluminescence in the presence of the detection device. As an example the detection reaction may be performed in a test tube or microwell plate housed in a luminometer or placed in front of a CCD camera in a housing adapted to receive test tubes or microwell plates. [0084] In some embodiments, light is measured in an instrument for performing assays. Such an instrument comprises one or more reaction vessels for performing assays. The reaction vessels may comprise disposable wells, tubes or cartridges into which are dispensed samples and other reagents needed for performing tests. The instrument may further comprise pumps and injectors for dispensing liquids and particles. The instrument may further comprise means for transporting reaction vessels to one or more zones within the instrument. The instrument further comprises a light measurement device, typically a photomultiplier, as well as means for recording one or more characteristics of the light produced by a sample in an assay. The instrument may further comprise a data collection, analysis and storage system, typically a computer. Characteristics of the light that may be measured in an assay include peak intensity, integrated intensity for some or all of the light emitting period, rate of change of light intensity, spectral distribution, ratio of intensity at more than one wavelength, time to achieve peak intensity, or time to achieve some fraction of peak intensity. Uses [0085] The present assay methods find applicability in many types of specific binding pair assays. Foremost among these are chemiluminescent enzyme linked immunoassays, such as an ELISA. Various assay formats and the protocols for performing the immunochemical steps are well known in the art and include both competitive assays and sandwich assays. Types of substances that can be assayed by immunoassay according to the present methods include proteins, peptides, antibodies, haptens, drugs, steroids and other substances that are generally known in the art of immunoassay. [0086] The methods provided herein are also useful for the detection of nucleic acids. The presented methods may use enzyme-labeled nucleic acid probes. Exemplary methods include solution hybridization assays, DNA detection in Southern blotting, RNA by Northern blotting, DNA sequencing, DNA fingerprinting, colony hybridizations and plaque lifts, the conduct of which is well known to those of skill in the art. [0087] In addition to the aforementioned antigen-antibody, hapten-antibody or antibody-antibody pairs, specific binding pairs also can include complementary oligonucleotides or polynucleotides, avidin-biotin, streptavidin-biotin, hormone-receptor, lectin-carbohydrate, IgG protein A, binding protein-receptor, nucleic acid-nucleic acid binding protein and nucleic acid-anti-nucleic acid antibody. Receptor assays used in screening drug candidates are another area of use for the present methods. III. Examples [0088] The following example demonstrates an immunoassay of an analyte, Prostate Specific Antigen (PSA), wherein hydrogen peroxide is generated through the reaction of glucose oxidase with glucose, where the glucose oxidase is bound with the surface of the solid phase. [0089] The antibodies used for this example were those found in the Hybritech® PSA Assay (Item No. 37200) of the Access® Immunoassay System (Beckman Coulter, Inc., Fullerton, Calif., USA). The antibodies in the described embodiment are used in the same orientation, that is, the Hybritech® solid phase capture antibody is located on the solid phase support surface and the Hybritech® conjugate antibody is used for the peroxidase conjugate. It should be noted that while this experiment utilized the Hybritech® PSA antibodies one skilled in the art will recognize that other suitable antibody pairs could be substituted so long as such antibody pair provided the ability to form a specific binding pair sandwich with the analyte antigen. Unique buffers are described. Buffers not described are obvious to one skilled in the art. [0000] [0090] To prepare the base microparticles Bovine Serum Albumin (BSA) was biotinylated with 4× molar excess of biotin-LC-sulfoNHS (Pierce Biotechnology Inc., Rockford, Ill., USA). Unbound reactants were removed via desalting or dialysis. The biotin-BSA was then reacted with a 5× molar excess of Compound 17 in 20 mM sodium phosphate pH 7.2: DMSO 75:25, v/v) followed by desalting in the same buffer. The dual labeled (biotin and 17) BSA was then coupled with tosyl activated M280 microparticles (Invitrogen Corporation, Carlsbad, Calif., USA) in a 0.1M borate buffer pH 9.5 at a concentration of ca. 20 μg labeled BSA per mg of microparticles for 16-24 h at 40° C. After coupling the microparticles were stripped for 1 h at 40° C. with 0.2 M TRIS base, 2% SDS, pH ˜11. The stripping process was repeated one additional time. Microparticles were then suspended in a 0.1% BSA/TRIS buffered saline (BSA/TBS) buffer and streptavidin (SA) was added at approximately 15 μg SA per mg microparticles. Streptavidin was mixed with the microparticles for 45-50 min at room temperature. The microparticles were then washed three times and suspended in the same BSA/TBS. This describes the preparation of the base microparticles. Internal studies have shown these base microparticles are capable of binding approximately 5 μg of biotinylated capture antibody per mg of microparticles. [0091] To prepare the actual test microparticles glucose oxidase (GOX), obtained from Sigma Aldrich, St. Louis, Mo., USA was biotinylated with a 5× molar excess of biotin-PEO 4 —NHS, obtained from Pierce Biotechnology Inc., Rockford, Ill., USA. Unbound reactants were removed by desalting or dialysis. The PSA capture antibody was also biotinylated with a 5× molar excess of biotin-LC-sulfoNHS, (Pierce) and unbound reactants were removed by desalting or dialysis. To the base microparticles (above) the biotin capture antibody was added at 4 μg per mg of microparticles and the biotin GOX was added at 1 μg per mg of microparticles. The biotinylated proteins were mixed with the microparticles overnight at room temperature. After incubating all unbound reactants were removed by three washes in BSA/TBS. [0092] The second analyte-specific binding partner, or antibody was prepared by first the activation of the Hybritech antibody with a 50× molar excess of DL-N-Acetylhomocysteine thiolactone (AHTL; Sigma-Aldrich) in 0.1M carbonate pH 9 for 1 h at room temperature. Excess reactant was removed by desalting into PBS plus 1 mM EDTA. At the same time HRP, (Roche Diagnostics, Indianapolis, Ind., USA) was activated with a 10× molar excess of sulfo-SMCC, (Pierce) for 1 h at room temperature. Excess reactant was removed by desalting into PBS. The activated Hybritech antibody and HRP were mixed together in a 1:5 (Ab:HRP) molar ratio and are allowed to react at room temperature for 1-2 hours. The reaction was stopped by the addition of a slight molar excess of 2-mercaptoethanol, then N-ethyl maleimide. The antibody-HRP second analyte-specific binding partner was then separated from unbound reactants by SEC. Trigger solution consisted of 0.1M sodium phosphate pH ˜7.2, 0.2M glucose, and 8 mM p-hydroxycinnamic acid. [0093] To perform an assay the following stocks were prepared from the above described components. Microparticles were diluted to 1.75 mg/mL in BSA/TBS. Conjugate was diluted to 2 μg/mL in BSA/TBS. The reaction mixture was prepared by mixing the microparticle stock, a conjugate stock, buffer, and sample in the following ratio: 25:45:15:15 (volumes ratio of Microparticles:BSA/TBS:Conjugate:Sample) in this written order. The reaction mixture was incubated for 30 min at 37° C., then 100 μL of trigger solution was added and the light intensity recorded. To evaluate the effect of catalase (Sigma-Aldrich) the enzyme was added to the BSA/TBS added to the reaction at a concentration of 2 μg/ml. [0094] Signal (light) was captured and quantified immediately after addition of the trigger solution with a PMT. The signal expressed as relative luminometer (light) units RLUs is provided in the following table. [0000] PSA Average RLU (ng/mL) −catalase +catalase 0 1011 491 0.5 1184 1860 2 2054 712 10 3214 2532 75 15887 9792 150 21935 18878

Nonseparation assay methods using peroxide generating enzymes in combination with a solid support for analyte detection are disclosed. The present assay methods provide a high degree of sensitivity, are simple and efficient to perform, and are excellent tools for diagnostic and high through-put screening applications.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional application of U.S. application Ser. No. 13/577,288, which is a National Stage of PCT/JP2011/053650, filed Feb. 21, 2011. The disclosures of application Ser. No. 13/577,288 and PCT/JP2011/053650 are incorporated by reference herein in their entireties. The present application also claims priority of Japanese application 2010-040420, filed Feb. 25, 2010. TECHNICAL FIELD [0002] The present invention relates to, for example, a composition for an optical material, and specifically to, for example, a composition for an optical material which is preferable for an optical material such as a plastic lens, a prism, an optical fiber, an information recording substrate, a filter or the like, especially a plastic lens. BACKGROUND ART [0003] Plastic materials are lightweight, highly tough and easy to be dyed, and therefore are widely used recently for various types of optical materials, especially eyeglass lenses. Optical materials, especially eyeglass lenses, are specifically required to have, as physical properties, low specific gravity, high transparency and low yellow index, high heat resistance, high strength and the like, and as optical properties, high refractive index and high Abbe number. A high refractive index allows a lens to be thinner, and a high Abbe number reduces the chromatic aberration of a lens. However, as the refractive index is increased, the Abbe number is decreased. Thus, it has been studied to improve both of the refractive index and the Abbe number. Among methods which have been proposed, a representative method uses an episulfide compound as described in Patent Document 1. [0004] Meanwhile, in order to improve the oxidation resistance, Patent Document 2 proposes adding a thiol compound to an episulfide compound. [0005] It has also been studied to improve the refractive index. Patent Documents 3 and 4 propose a composition containing sulfur, episulfide and thiol. [0006] However, these composition containing thiol have a problem of being clouded when being polymerized and thus cured. These composition are to be used for optical materials. Therefore, if the composition are clouded after being cured, the composition become all defective. This causes a massive loss. Accordingly, a technique for estimating, on a pre-curing stage, whether the composition will be clouded or not after being cured, so that the composition is determined as being good or not has been desired. CITATION LIST Patent Literature [0007] Patent Document 1: Japanese Laid-Open Patent Publication No. H9-110979 [0008] Patent Document 2: Japanese Laid-Open Patent Publication No. H10-298287 [0009] Patent Document 3: Japanese Laid-Open Patent Publication No. 2001-2783 [0010] Patent Document 4: Japanese Laid-Open Patent Publication No. 2004-137481 SUMMARY OF INVENTION Technical Problem [0011] A problem to be solved by the present invention is to provide a composition for an optical material comprising polythiol which can be estimated, on a pre-polymerization/curing stage, as being clouded or not clouded after being cured, and thus can be determined as being good or defective. Solution to Problem [0012] As a result of accumulating active studies in light of such circumstances, the present inventors solved the problem by, for example, a composition for an optical material comprising polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide; and thus achieved the present invention. [0013] Namely, the present invention is as follows. [0014] <1> A composition for an optical material comprising polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. [0015] <2> The composition for an optical material according to <1> above, further comprising sulfur. [0016] <3> The composition for an optical material according to <2> above, wherein the episulfide and the sulfur are preliminarily polymerized. [0017] <4> The composition for an optical material according to <2> above, wherein 10% or more of the sulfur is preliminarily polymerized with the episulfide. [0018] <5> The composition for an optical material according to any one of <1> through <4> above, which is obtained as a result of degassing. [0019] <6> An optical material obtained by polymerizing the composition for an optical material according to any one of <1> through <5> above. [0020] <7> The optical material according to <6> above, which is obtained as a result of annealing the post-polymerization composition for an optical material. [0021] <8> A method for producing a composition for an optical material, comprising the step of mixing polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. [0022] <9> The method for producing a composition for an optical material according to <8> above, further comprising the step of incorporating sulfur. [0023] <10> The method for producing a composition for an optical material according to <8> or <9> above, further comprising the step of degassing. Advantageous Effects of Invention [0024] According to the present invention, it has now become possible to provide, for example, a composition for an optical material containing polythiol which can be estimated, on a pre-polymerization/curing stage, as being clouded or not clouded after being polymerized and thus cured, and so can be determined as being good or defective. Provision of such a composition has been difficult with the conventional art. DESCRIPTION OF EMBODIMENTS [0025] According to the present invention, any of all polythiol compounds is usable. Specific examples thereof include methanedithiol, 1,2-dimercaptoethane, 2,2-dimercaptopropane, 1,3-dimercaptopropane, 1,2,3-trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis(2-mercaptoethyl)sulfide, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, 1,8-dimercapto-3,6-dioxaoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl 1,4-dimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 1,1,1-tris(mercaptomethyl)propane, tetrakis(mercaptomethyl)methane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, ethyleneglycolbis(2-mercaptoacetate), ethyleneglycolbis(3-mercaptopropionate), 1,4-butanediolbis(2-mercaptoacetate), 1,4-butanediolbis(3-mercaptopropionate), trimethylolpropanetris(2-mercaptoacetate), trimethylolpropanetris(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), pentaerythritoltetrakis(3-mercaptopropionate), 1,1-dimercaptocyclohexane, 1,2-dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, 2,5-bis(mercaptomethyl)-1,4-dithiane, 2,5-bis(mercaptoethyl)-1,4-dithiane, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, bis(4-mercaptophenyl)sulfide, bis(4-mercaptophenyl)ether, 2,2-bis(4-mercaptophenyl)propane, bis(4-mercaptomethylphenyl)sulfide, bis(4-mercaptomethylphenyl)ether, 2,2-bis(4-mercaptomethylphenyl)propane, and the like. [0026] Specific examples of preferable compounds among the above-listed compounds include bis(2-mercaptoethyl)sulfide, pentaerythritoltetrakis(2-mercaptoacetate), pentaerythritoltetrakis(3-mercaptopropionate), 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,3-bis(mercaptomethyl)benzene, and 1,4-bis(mercaptomethyl)benzene. Specific examples of more preferable compounds include bis(2-mercaptoethyl)sulfide and 1,3-bis(mercaptomethyl)benzene. Bis(2-mercaptoethyl)sulfide is most preferable. [0027] According to the present invention, the turbidity is measured by an integrating sphere type turbidimeter on the basis of the kaolin standard solution in conformity to JIS K0101. The acceleration is measured after polythiol is stored at 50° C. for 7 days. [0028] After these measurements, polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days is used. Preferably, the initial turbidity, namely, the turbidity immediately before storage at 50° C. for 7 days is 0.3 ppm or less, and the turbidity after storage at 50° C. for 7 days is 0.4 ppm or less. More preferably, the initial turbidity is 0.2 ppm or less, and the turbidity after storage at 50° C. for 7 days is 0.3 ppm or less. [0029] When the initial turbidity exceeds 0.5 ppm or the turbidity after storage at 50° C. for 7 days exceeds 0.6 ppm, an optical material such as a post-polymerization/curing lens is clouded and is not usable. Accordingly, by measuring the initial turbidity and the turbidity after storage at 50° C. for 7 days of polythiol, the estimation on whether the polythiol will be clouded or not can be made in the state where the polythiol has not been polymerized/cured. Thus, the quality of the polythiol can be determined. [0030] The actual operation is conducted as follows. First, the initial turbidity of polythiol is measured. A part of the polythiol is taken out and stored at 50° C. for 7 days, and then the turbidity thereof is measured. In the case where both of the values are in the above-described ranges, an optical material formed of the polythiol will not be clouded. Thus, this polythiol is determined as being usable. [0031] Where the sum of polythiol and episulfide is 100 parts by weight, a polythiol compound used in the present invention is usually contained in an amount of 1 to 30 parts by weight, preferably 2 to 20 parts by weight, and especially preferably 3 to 15 parts by weight. [0032] According to the present invention, any of all episulfide compounds is usable. Specific examples thereof will be listed below regarding each type of compounds, i.e., compounds having a chain aliphatic structure, compounds having an aliphatic cyclic structure, and compounds having an aromatic structure. [0033] The compounds having a chain aliphatic structure include compounds expressed by the following formula (1): [0000] [0000] (where m represents an integer of 0 to 4, and n represents an integer of 0 or 1). [0034] The compounds having an aliphatic cyclic structure include compounds expressed by the following formula (2) or (3): [0000] [0000] (where p and q each represent an integer of 0 to 4). [0000] [0000] (where p and q each represent an integer of 0 to 4). [0035] The compounds having an aromatic structure include compounds expressed by the following formula (4): [0000] [0000] (where p and q each represent an integer of 0 to 4). [0036] Among the above-shown compounds, the compounds expressed by formula (1) above having a chain aliphatic structure are preferable. Specific examples thereof include bis(β-epithiopropyl)sulfide, bis(β-epithiopropyl)disulfide, bis(β-epithiopropyl)trisulfide, bis(β-epithiopropylthio)methane, 1,2-bis(β-epithiopropylthio)ethane, 1,3-bis(β-epithiopropylthio)propane, 1,4-bis(β-epithiopropylthio)butane, and bis(β-epithiopropylthioethyl)sulfide. Bis(β-epithiopropyl)sulfide (in formula (1) above, n=0) and bis(β-epithiopropyl)disulfide (in formula (1) above, m=0, n=1) are especially preferable. Bis(β-epithiopropyl)sulfide (in formula (1) above, n=0) is most preferable. [0037] Examples of the episulfide compounds having an aliphatic cyclic structure include 1,3- and 1,4-bis(β-epithiopropylthio)cyclohexane (in formula (2) above, p=0, q=0), 1,3- and 1,4-(β-epithiopropylthiomethyl)cyclohexane (in formula (2) above, p=1, q=1), bis[4-(β-epithiopropylthio)cyclohexyl]methane, 2,2-bis[4-(β-epithiopropylthio)cyclohexyl]propane, bis[4-(β-epithiopropylthio)cyclohexyl]sulfide, 2,5-bis(β-epithiopropylthio)-1,4-dithiane (in formula (3) above, p=0, q=0), 2,5-bis(β-epithiopropylthioethylthiomethyl)-1,4-dithiane, and the like. [0038] Examples of the episulfide compounds having an aromatic structure include 1,3- and 1,4-bis(β-epithiopropylthio)benzene (in formula (4) above, p=0, q=0), 1,3- and 1,4-bis(β-epithiopropylthiomethyl)benzene (in formula (4) above, p=1, q=1), bis[4-(β-epithiopropylthio)phenyl)]methane, 2,2-bis[4-(β-epithiopropylthio)phenyl]propane, bis[4-(β-epithiopropylthio)phenyl)]sulfide, bis[4-(β-epithiopropylthio)phenyl)]sulfine, 4,4-bis(β-epithiopropylthio)biphenyl, and the like. [0039] Where the sum of polythiol and episulfide is 100 parts by weight, an episulfide compound used in the present invention is usually contained in an amount of 70 to 90 parts by weight, preferably 80 to 98 parts by weight, and especially preferably 85 to 97 parts by weight. [0040] A composition for an optical material according to the present invention may further contain sulfur. When sulfur is used, it is preferable to react an episulfide compound with sulfur preliminarily. Such a preliminary polymerization reaction is performed, preferably under the conditions of at −10° C. to 120° C. for 0.1 to 240 hours, more preferably under the conditions of at 0° C. to 100° C. for 0.1 to 120 hours, and especially preferably under the conditions of at 20° C. to 80° C. for 0.1 to 60 hours. In order to promote the preliminary reaction, it is effective to use a catalyst. Preferable examples of the catalyst include 2-mercapto-1-methylimidazole, triphenylphosphine, 3,5-dimethylpyrazole, N-cyclohexyl-2-benzothiazolylsulfineamide, dipentamethylenethiuramtetrasulfide, tetrabutylthiuramdisulfide, tetraethylthiuramdisulfide, 1,2,3-triphenylguanidine, 1,3-diphenylguanidine, 1,1,3,3-tetramethyleneguanidine, aminoguanidineurea, trimethylthiourea, tetraethylthiourea, dimethylethylthiourea, zinc dibutyldithiocarbamate, zinc dibentyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate, pipecorium pipecoryldithiocarbamate, and the like. In addition, it is preferable to consume 10% or more of sulfur by this preliminary polymerization reaction (where the amount of sulfur before the reaction is 100%), and it is more preferable to consume 20% or more of sulfur. The preliminary reaction may be performed in an optional atmosphere, for example, under inert gas such as air, nitrogen or the like, in a sealed state at normal pressure or at a raised or reduced pressure, or the like. In order to detect how much the preliminary reaction has proceeded, a liquid chromatograph or a refractive index meter can be used. [0041] Where the sum of polythiol and episulfide is 100 parts by weight, sulfur, which is used in a preferable embodiment of the present invention, is usually contained in an amount of 0.1 to 40 parts by weight, preferably 0.5 to 30 parts by weight, and especially preferably 5 to 25 parts by weight. [0042] According to the present invention, it is preferable to perform degassing (deaeration) of the composition for an optical material in advance. The degassing is performed under a reduced pressure before, during or after the mixture of a compound reactive with a part of, or all of, the components of the composition, a polymerization catalyst, and an additive. Preferably, the degassing is performed at a reduced pressure during or after the mixing. Preferably, the degassing is performed under the conditions of at a reduced pressure of 0.001 to 50 torr for 1 minute to 24 hours at 0° C. to 100° C. The degree of pressure reduction is preferably 0.005 to 25 torr, and more preferably 0.01 to 10 torr. The degree of pressure reduction may be varied within such a range. The degassing time is preferably 5 minutes to 18 hours, and more preferably 10 minutes to 12 hours. The temperature for the degassing is preferably 5° C. to 80° C., and more preferably 10° C. to 60° C. The temperature may be varied within such a range. When performing the aeration, updating the interface of the composition for a resin by stirring, blowing-in of gas, vibration by ultrasonic waves or the like is preferable in order to improve the effect of the degassing. A component which is removed by the degassing is mainly, for example, dissolved gas such as hydrogen sulfide or the like or a low boiling point substance such as thiol or the like. There is no specific limitation on the type of target of removal as long as the effect of the present invention is provided. [0043] In addition, filtrating out impurities from the composition for an optical material or pre-mixing materials of the composition by use of a filter having a pore diameter of about 0.05 to 10 μm for the purpose of refinement is preferable in order to improve the quality of the optical material according to the present invention. [0044] Hereinafter, a method for producing an optical material by polymerizing a composition for an optical material according to the present invention will be described. [0045] Examples of a catalyst usable for polymerizing and thus curing the composition for an optical material include amine, onium salts, and phosphine compounds. Specific examples thereof include amine, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, and phosphine compounds. Among these, quaternary ammonium salts, quaternary phosphonium salts and phosphine compounds are highly compatible with the composition and are preferable. Quaternary phosphonium salts are more preferable. Specific examples of the preferable compounds include quaternary ammonium salts such as tetra-n-butylammoniumbromide, tetraphenylammoniumbromide, triethylbenzylammoniumchloride, cetyldimethylbenzylammoniumchloride, 1-n-dodecylpyridiniumchloride, and the like; quaternary phosphonium salts such as tetra-n-butylphosphoniumbromide, tetraphenylphosphoniumbromide, and the like; and phosphine compounds such as triphenylphosphine and the like. Among these compounds, triethylbenzylammoniumchloride and tetra-n-butylphosphoniumbromide are more preferable, and tetra-n-butylphosphoniumbromide is most preferable. The polymerization catalysts may be used independently or in a mixture of two or more. [0046] The amount of the polymerization catalyst varies in accordance with the components, mixing ratio and polymerization/curing method of the composition and thus cannot be unconditionally determined. The amount of the polymerization catalyst is usually 0.001 wt. % or greater and 5 wt. % or less, preferably 0.01 wt. % or greater and 1 wt. % or less, and most preferably 0.01 wt. % or greater and 0.5 wt. % or less, with respect to the total amount of the composition for an optical material. When the amount of the polymerization catalyst is greater than 5 wt. %, the refractive index and the heat resistance of the cured product may be lowered and thus the cured product may be colored. When the amount of the polymerization catalyst is less than 0.001 wt. %, the composition may not be sufficiently cured and the heat resistance of the resultant product may be insufficient. [0047] For polymerizing and thus curing the composition for an optical material, a polymerization adjusting agent may be optionally added for the purpose of extending the pot life or dispersing the polymerization heat. As the polymerization adjusting agent, any of the group 13 through 16 halides in the long form periodic table is usable. Among these compounds, preferable compounds include halides of silicon, germanium, tin and antimony. More preferable compounds include chlorides of germanium, tin and antimony having an alkyl group. Specific examples of the more preferable compounds include dibutyltindichloride, butyltintrichloride, dioctyltindichloride, octyltintrichloride, dibutyldichlorogermanium, butyltrichlorogermanium, diphenyldichlorogennanium, phenyltrichlorogermanium, and triphenylantimonydichloride. A specific example of most preferable compounds is dibutyltinchloride. The polymerization adjusting agents may be used independently or in a mixture of two or more. [0048] The amount of the polymerization adjusting agent is usually 0.0001 wt. % to 5.0 wt. %, preferably 0.0005 wt. % to 3.0 wt. % or less, and most preferably 0.001 wt. % to 2.0 wt. % or less, with respect to the total amount of the composition for an optical material. [0049] For polymerizing and thus curing the composition for an optical material according to the present invention and thus for obtaining an optical material, any of additives such as a known antioxidant, ultraviolet absorber, blueing agent and the like can be added to improve the practicality of the material to be obtained. [0050] Preferable examples of the antioxidant include phenol derivatives. Among these, preferable compounds include polyhydric phenols and halogen-substituted phenols. More preferable compounds include catechols, pyrogallols, alkyl-substituted catechols. Most preferable compounds include catechols and pyrogallols. Preferable examples of the ultraviolet absorber include benzotriazole-based compounds. Specific examples of the preferable compounds among these compounds include 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, 5-chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole, and 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole. Preferable examples of the blueing agent include anthraquinone-based compounds. [0051] In the case where the composition for an optical material according to the present invention is easily delaminated from the mold during the polymerization, a known external and/or internal adhesiveness improving agent can be used to control and improve the adhesiveness of the cured product to be obtained to the mold. Examples of the adhesiveness improving agent include known silane coupling agents, titanate compounds and the like. These adhesiveness improving agents may be used independently or in a mixture of two or more. The amount of the adhesiveness improving agent is usually 0.0001 wt. % to 5 wt. % with respect to the total amount of the composition for an optical material. By contrast, in the case where the composition for an optical material according to the present invention is difficult to be delaminated from the mold after the polymerization, a known external and/or internal releasing agent can be used to improve the releasability, from the mold, of the cured product to be obtained. Examples of the releasing agent include fluorine-based nonion surfactants, silicon-based nonion surfactants, ester phosphate, acid ester phosphate, oxyalkylene-type acid ester phosphate, alkali metal salts of acid ester phosphate, alkali metal salts of oxyalkylene-type acid ester phosphate, metal salts of higher fatty acid, higher fatty acid ester, paraffin, wax, higher aliphatic amide, higher aliphatic alcohol, polysyloxanes, aliphatic amineethyleneoxide adducts, and the like. These releasing agents may be used independently or in a mixture of two or more. The amount of the releasing agent is usually 0.0001 wt. % to 5 wt. % with respect to the total amount of the composition for an optical material. [0052] A method for producing an optical material by polymerizing and thus curing a composition for an optical material according to the present invention is, in more detail, as follows. The components of the composition, and additives such as the antioxidant, ultraviolet absorber, polymerization catalyst, radical polymerization initiator, adhesiveness improving agent, releasing agent and the like described above may be all mixed together in the same vessel while being stirred; the components and additives may be added step by step and mixed; or different groups of the components and additives may be mixed separately and then the groups may be added together in the same vessel. The components and sub components may be mixed in any order. There is basically no specific limitation on the set temperature, the time and the like for mixing as long as the components and additives are sufficiently mixed. [0053] The composition for an optical material obtained as a result of the above-described reaction and processing is injected into a glass or metal mold, and is heated or irradiated with active energy rays such as ultraviolet rays or the like, so that the polymerization/curing proceeds. Then, the resultant substance is removed from the mold. In this manner, the optical material is produced. For producing an optical material, the polymerization/curing of the composition for an optical material is preferably performed by heating. In this case, the curing time is 0.1 to 200 hours, usually 1 to 100 hours. The curing temperature is −10° C. to 160° C., usually −10° C. to 140° C. The polymerization can be performed by holding the polymerization temperature for a prescribed time period, increasing the temperature at a rate of 0.1° C. to 100° C./hour, decreasing the temperature at a rate of 0.1° C. to 100° C./hour, or a combination thereof. In the process for producing an optical material according to the present invention, annealing the post-polymerization/curing product at a temperature of 50° C. to 150° C. for about 10 minutes to 5 hours is preferable in order to remove distortion from the optical material. In addition, surface treatment such as dyeing, hard-coating, anti-impact-coating, reflection prevention, provision of antifogging property or the like may be performed. EXAMPLES [0054] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. The evaluation was performed by the following method. [0055] Turbidity: The initial turbidity and the turbidity after storage at 50° C. for 7 days of polythiol were measured by use of T-2600DA turbidimeter produced by Tokyo Denshoku Co., Ltd. [0056] Transparency: Ten lenses having a lens diameter of 70 mm and a degree of +5D were produced by use of optical materials produced by polymerization of compositions for an optical material. The lenses were observed in a darkroom under fluorescent light. The optical materials were evaluated as follows: the optical material used for producing the ten glasses, none of which was clouded, was rated “4”; the optical material used for producing the ten glasses, nine of which were not clouded, was rated “3”; the optical material used for producing the ten glasses, seven or eight of which were not clouded, was rated “2”; and the optical material used for producing the ten glasses, six or less of which were not clouded, was rated “1”. The optical materials rated “2” or higher are acceptable. Example 1 [0057] A composition for an optical material, and an optical material, according to the present invention were produced by use of bis(1-mercaptoethyl)sulfide having an initial turbidity of 0.15 and a turbidity of 0.15 after storage at 50° C. for 7 days in accordance with production method A described below. The transparency of the obtained optical material was good and “4”. The results are shown in Table 1. Examples 2 Through 6 [0058] A composition for an optical material, and an optical material, according to the present invention were produced by use of bis(2-mercaptoethyl)sulfide having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Examples 7 Through 12 [0059] A composition for an optical material, and an optical material, according to the present invention were produced by use of 1,3-bis(mercaptomethyl)benzene having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Comparative Examples 1 Through 4 [0060] A composition for an optical material, and an optical material, were produced by use of bis(2-mercaptoethyl)sulfide having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Comparative Examples 5 Through 8 [0061] A composition for an optical material, and an optical material, were produced by use of 1,3-bis(2-mercaptomethyl)benzene having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. [0062] The production methods used in the examples and the comparative examples were as follows. Method A: [0063] To a composition containing 5 parts by weight of bis(2-mercaptoethyl)sulfide and 95 parts by weight of bis(β-epithiopropyl)sulfide, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Method B: [0064] To 78 parts by weight of bis(β-epithiopropyl)sulfide and 14 parts by weight of sulfur, 0.5 parts by weight of mercaptomethylimidazole was added. These compounds were preliminarily polymerized and thus cured at 60° C. The consumption ratio of sulfur at this point was 50% by an HPLC analysis (GPC mode). After the resultant substance was cooled down to 20° C., a mixture solution of 7 parts by weight of bis(2-mercaptoethyl)sulfide, 0.2 parts by weight of dibutyltindichloride, and 0.03 parts by weight of tetra-n-butylphosphoniumbromide was added. These compounds were mixed uniformly and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Method C: [0065] To a composition containing 5 parts by weight of 1,3-bis(mercaptomethyl)benzene and 95 parts by weight of bis(β-epithiopropyl)sulfide, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold, Thus, an optical material was obtained. Method D: [0066] To 78 parts by weight of bis(β-epithiopropyl)sulfide and 14 parts by weight of sulfur, 0.5 parts by weight of mercaptomethylimidazole was added. These compounds were preliminarily polymerized and thus cured at 60° C. The consumption ratio of sulfur at this point was 46% by an HPLC analysis (GPC mode). After the resultant substance was cooled down to 20° C., a mixture solution of 7 parts by weight of 1,3-bis(mercaptomethyl)benzene, 0.2 parts by weight of dibutyltindichloride, and 0.03 parts by weight of tetra-n-butylphosphoniumbromide was added. These compounds were mixed uniformly and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Preliminary Experiment [0067] To 100 parts by weight of bis(β-epithiopropyl)sulfide to be used in the examples and the comparative examples, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed. The resultant mixture was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. The transparency of the optical material was good and “4”. An episulfide compound which was confirmed to maintain a good transparency even after being polymerized and thus cured in this manner was used. [0000] TABLE 1 Initial Post-storage Other turbidity turbidity main Polymerization Trans- Example Polythiol compound value value Episulfide compound component method parency Example 1 Bis(2-mercaptoethyl)sulfide 0.15 0.15 Bis(β-epithiopropyl)sulfide — A 4 Example 2 Bis(2-mercaptoethyl)sulfide 0.15 0.15 Bis(β-epithiopropyl)sulfide Sulfur B 4 Example 3 Bis(2-mercaptoethyl)sulfide 0.26 0.28 Bis(β-epithiopropyl)sulfide — A 3 Example 4 Bis(2-mercaptoethyl)sulfide 0.26 0.28 Bis(β-epithiopropyl)sulfide Sulfur B 3 Example 5 Bis(2-mercaptoethyl)sulfide 0.32 0.43 Bis(β-epithiopropyl)sulfide — A 2 Example 6 Bis(2-mercaptoethyl)sulfide 0.32 0.43 Bis(β-epithiopropyl)sulfide Sulfur B 2 Example 7 1,3-bis(2-mercaptomethyl)benzene 0.15 0.17 Bis(β-epithiopropyl)sulfide — C 4 Example 8 1,3-bis(2-mercaptomethyl)benzene 0.15 0.17 Bis(β-epithiopropyl)sulfide Sulfur D 4 Example 9 1,3-bis(2-mercaptomethyl)benzene 0.26 0.33 Bis(β-epithiopropyl)sulfide — C 3 Example 10 1,3-bis(2-mercaptomethyl)benzene 0.26 0.33 Bis(β-epithiopropyl)sulfide Sulfur D 3 Example 11 1,3-bis(2-mercaptomethyl)benzene 0.45 0.58 Bis(β-epithiopropyl)sulfide — C 2 Example 12 1,3-bis(2-mercaptomethyl)benzene 0.45 0.58 Bis(β-epithiopropyl)sulfide Sulfur D 2 Comparative Bis(2-mercaptoethyl)sulfide 0.18 0.63 Bis(β-epithiopropyl)sulfide — A 1 example 1 Comparative Bis(2-mercaptoethyl)sulfide 0.18 0.63 Bis(β-epithiopropyl)sulfide Sulfur B 1 example 2 Comparative Bis(2-mercaptoethyl)sulfide 0.51 0.51 Bis(β-epithiopropyl)sulfide — A 1 example 3 Comparative Bis(2-mercaptoethyl)sulfide 0.51 0.51 Bis(β-epithiopropyl)sulfide Sulfur B 1 example 4 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.19 0.65 Bis(β-epithiopropyl)sulfide — C 1 example 5 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.19 0.65 Bis(β-epithiopropyl)sulfide Sulfur D 1 example 6 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.55 0.57 Bis(β-epithiopropyl)sulfide — C 1 example 7 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.55 0.57 Bis(β-epithiopropyl)sulfide Sulfur D 1 example 8 [0068] In each of the above examples, a composition for an optical material using polythiol fulfilling the conditions that the initial turbidity is 0.5 ppm or less and the turbidity after storage at 50° C. for 7 days is 0.6 ppm or less was polymerized. As a result, post-curing cloudiness was prevented and a high transparency was realized. Thus, according to the present invention, it can be estimated, before the polymerization reaction, whether a composition for an optical material will be clouded or not after being polymerized and thus cured. Thus, it can be determined whether the composition is good or not. Therefore, only an optical material having good properties can be selectably produced. As a result, the composition for an optical material can be effectively utilized and also a superb optical material can be produced.

The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

RELATED APPLICATIONS This application claims priority to U.S. Provisional application 60/713,936, which is incorporated herein by reference. FIELD OF THE INVENTION This invention relates to the area of automated musical instruments, particularly pianos, the invention also relates to the method of creating or authoring music sequences files for use with the automated musical instrument. BACKGROUND OF THE INVENTION Automated musical instruments, such as pianos, are well known in the art. Such instruments are typically acoustic instruments that use mechanical actuators to operate the instrument. The actuators receive commands of articulation events or music sequences to control or play the instrument. The music sequences are delivered to the instrument by a controller. There have been a number of attempts to have an automated instrument play in synchronization or accompaniment with a prerecorded CD or hard drive. Such attempts are described in U.S. Pat. Nos. 5,138,925, 5,300,725, 5,148,419 and 5,313,011. In order allow for synchronous play, those previous attempts rely upon timing information presented on a sub-channel of the CD to provide a common time frame for both the music sequences and the CD audio to reference. While such an arrangement is sufficient, it suffers from the limited resolution offered by the timing information of the CD sub-channel. The timing information of the CD sub-channel has a period or resolution of 13 milliseconds, which is not accurate enough for some piano sequences. The present invention described herein uses the timing inherent in the CD audio data as the time reference. By the use of this technique, the timing can have a period or resolution of 22.7 microseconds based upon the sample rate of 44.1 kHz of the digital audio data of the CD While listening to the automated instrument playing alone is entertaining for the user, some users desire to have the instrument play along with a commercial recording of a musical selection, thus allowing the user to experience the recorded selection accompanied by a live automated instrument. In early products for playing an automated piano in synchronism with a CD, the CD media contained music sequences that were pre-synchronized to a digital accompaniment music track encoded as linear PCM. For instance, the audio music track would be encoded as PCM on the left channel of the CD, and the music sequence, encoded as MIDI, would be encoded on the right channel. In the invention described herein, the system utilizes off the shelf commercially recorded CD, and music sequences specifically authored to play in synchronism with the musical selections on the CD. The music sequences are generally MIDI files stored on removable media such as SD cards and the like. One skilled in the art will recognize that there are many ways to deliver the music sequences, such as MIDI files, to the consumer and ultimately to the controller of the automated musical instrument, and SD cards are but one example. SUMMARY OF THE INVENTION The system described herein includes a controller for delivering the music sequences to the automated musical instrument. The controller is also in communication with a drive capable of playing digital media such as a CD. The controller, using the CD audio data as a time reference, delivers the music sequences to the automated musical instrument so that the instrument plays in synchronism with the selection playing on the CD. One skilled in the art will recognize that the controller could also host and act as the player for the music sequence with the appropriate software. The following terms and definitions are used in this specification. The definitions included herein are to add meaning to terms and are not meant to limit or otherwise supplant meanings that are understood by those skilled in the art. MIDI—Acronym for Musical Instrument Digital Interface. MIDI is a music industry standard for digitally communicating musical instrument articulation events as a sequence of one or more bytes per event. The standard includes mechanical, electrical and byte signaling specifications. MIDI Interface—A physical interface across which MIDI bytes are sent and/or received. MIDI Event—A byte sequence that encodes a single musical instrument articulation event such as ‘key on’ or ‘sustain pedal depressed.’ MIDI Sequence—A chronological sequence of time-stamped MIDI events that encapsulates a performance of one or more musical instruments. MIDI Sequencer—A device that plays a MIDI Sequence in real time for the purpose of reproducing a musical performance. Standard MIDI File (SMF)—A music industry standard for storing and retrieving MIDI Sequences to and from a digital data file commonly referred to as MIDI file. Pianomation—A system for translating MIDI events to electro-mechanical activity for the purpose of automating an acoustic piano, or other automated musical instrument. Controller—An electronic device used to drive Pianomation with music sequences, such as MIDI Events from various media. DVD—Acronym for the consumer electronics Digital Video Disc standard and media. CD Player—A device, such as an optical drive, that is capable of playing a CD. CD Player Subsystem—An electronic Subsystem used to play CDs such as an integrated CD player ASIC and related electronic components contained within a larger system such as a Controller. Music Sequence—A term used in this application to generically refer to a chronological sequence of time-stamped digital musical instrument articulation events that encapsulates a performance of one or more musical instruments. This could be a SMF, a MIDI Sequence, or an otherwise encoded sequence that achieves the same objective. Sync-Along CD—The technique described herein for synchronizing a music sequence to a CD Player or CD Player Subsystem. Sync-Along CD Device—The device that implements the technique. This device can either attach to or be contained within a controller. PCM—Acronym for Pulse Code Modulation. This term refers to the linear digital encoding of instantaneous audio amplitude at a constant sample rate. This is also referred to as uncompressed digital audio. In the present invention, the controller, through use of a CD drive and subsystem incorporated into the controller, acts as both the MIDI Sequencer and the CD playback device, so the controller has inherent and immediate knowledge of what CD audio track is being played and what that track's time progress is authored music sequences to accompany commercial CD release. Typically, these commercial CDs will contain musical performances and the object is to drive the automated musical instrument synchronously along with the CD. These pre-authored music sequences are synchronized to the digital audio stream of the CD per track. This means that a particular track is extracted from the CD by the authoring system. Once this is done, it is played by the authoring system which is simultaneously capturing a live piano performance along with it and converting that performance to a music sequence, typically in MIDI format. The time stamps use the CD's extracted digital audio stream as its source of time reference rather than some other system time. Hence, the resulting music sequence is synchronized to the CD track on any playback system as long as the playback system uses the CD's digital audio stream as its time reference. Once the music sequence is authored or pre-authored as the process is alternatively named, it is associated with a CD song in some way. Since the Sync-Along device or controller is always the renderer of the CD Audio, it has specific knowledge of the CD that is being played, i.e., its Volume ID, and is always aware of exactly what track is being played. As such, the specific Volume ID and track number are stored as either Meta Events within the MIDI Sequence, or as part of the filename of the MIDI Sequence, allowing the controller to recognize what music sequence matches the CD being played. Therefore, when a controller is instructed by the user to playback a particular track, the system loads the requested music sequence along with its Volume ID and associated track number and checks to make sure that that particular CD is loaded for playback. Playback of audio CDs is implemented by the controller by reading the digital audio data, commonly referred to as Redbook audio data, directly off of the CD and sending that data to its DAC Subsystem for rendering to an analog signal. The DAC Subsystem itself is regulated by the audio rate of the DAC, which will nominally run at 44.1 kHz—the CD Audio sample rate. Hence, the data itself is consumed at the CD audio data rate by the DAC Subsystem which, via its DMA progress status, then provides the controller with an accurate digital audio time-base. Once playback of the CD audio track has been initiated, the controller resets its internal sequencer time-base and monitors the progression of audio time as measured by the DAC Subsystem. As this digital audio time progresses, the controller submits the MIDI events to the Piano system in accordance with the event timestamps. Thus, the CD and the automated musical instrument are synchronized. Since the automated Piano is a solenoid-actuated system, there is a measurable time delay from the time it receives a MIDI Event and the time it can actually sound a note on the automated acoustic Piano. In practice, his time can be as low as 100 ms or as high as 500 ms. Although the time is variable, the controller fixes the absolute delay from event reception to note sounding at 500 ms. Because of this delay, the controller advances the assertion of MIDI events during playback by 500 ms relative to the song start in order to maintain absolute synchronization to the CD as perceived by the user. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the operational components of the system of the invention. FIG. 2 is a front view of a controller. FIG. 3 is a diagram showing the timely relationship between an analog audio output and a music sequence. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1 , the synchronization system 20 described herein includes a controller 22 , an automated musical instrument, such as a piano 24 , and an amplifier 26 and speaker 28 . The amplifier 26 and speaker 28 can be incorporated into the controller 22 in an alternate embodiment, and need not be separate devices. Similarly, the amplifier 26 and speaker 28 can be replaced with any combination of devices that will allow the user to hear the recorded material on the CD placed into the CD drive 40 of the controller 22 . Thus, it is beneficial for the housing of the controller 22 to include an audio output port for connection of the amplifier 26 and speaker 28 , or other device used to transduce the audio signal output from the controller 22 . In the preferred embodiment, the output port is a pair of RCA jacks 60 to allow play of the left and right audio channels of the CD, as shown in FIG. 2 . The controller 22 is connected to the automated musical instrument or piano 24 by a communication channel 35 capable of carrying the music sequences from the controller 22 to the piano 24 . In the preferred embodiment, the communication channel is a high speed UART serial channel. The controller 22 includes a CD drive 40 , a digital to analog converter (DAC) subsystem 42 , a microprocessor 45 , random access memory (RAM) 47 , read only memory (ROM) 49 such as flash memory or an SD card or other removable media, a display 51 , and user controls 53 . The CD drive 40 can be any optical drive capable of reading a CD meeting the redbook specification and outputting the digital music data and subchannels having information regarding the volume ID, track number and non-music data regarding the CD. The CD drive 40 shares a communications channel 54 with the microprocessor 45 to convey information regarding the CD to the microprocessor 45 , and to receive control commands from the microprocessor 45 . The CD drive 40 also shares a communications channel 56 with the DAC subsystem 42 . The communications channel 56 serves to send the digital audio data from the CD drive to the DAC subsystem 42 . The DAC subsystem 42 of the preferred embodiment processes the digital audio data and converts the digital information into an analog signal. In the preferred embodiment, the DAC subsystem has two main parts, one of which may be incorporated into the microprocessor 45 . The first part is a DMA controller. The DMA controller moves audio data from the processor's RAM 47 to the DAC without processor intervention, as one skilled in the art will recognize In the preferred embodiment, the DMA controller is built into the TriMedia microprocessor. The DAC subsystem 42 also includes a digital to analog converter. In the preferred embodiment, the digital to analog converter is model CS4226 manufactured by Cirrus Logic. The DAC subsystem communicates with the microprocessor 45 by communications channel 55 . The communications channel is used to send information to the microprocessor 45 , access RAM 47 in communication with the microprocessor 45 , and to receive control commands from the microprocessor 45 . Among the information shared with the microprocessor 45 is the DMA progress status, or information regarding how many units of the digital audio data have been processed or output by the DAC subsystem 42 . The DAC subsystem 42 outputs the analog signal to the amplifier 26 by communications channel 56 . Communication channel 56 may include an output port 60 in the housing of the controller 22 . In the preferred embodiment, the output port is a pair of RCA jacks. The microprocessor 45 is in communication with RAM 47 by communication channel 60 . In the preferred embodiment, the controller 22 has 1 gigabyte of RAM, although other amounts can be used. The microprocessor 45 is also in communication with ROM 49 by communications channel 61 . The ROM 45 is used to provide the music sequences, preferably MIDI files, to the controller 45 . In the preferred embodiment, the ROM 49 is an SD card. The controller 22 is provided with a slot or interface 48 that will accept the SD card and link the card to the communications channel 61 . On skilled in the art will recognize that other types of memory could be used for ROM 49 , provided the controller 22 has the appropriate interface and the microprocessor 45 has the corresponding inputs and software to accommodate the type of memory used. In the preferred embodiment, the microprocessor is a TriMedia manufactured by Philips. Other microprocessors can be used to accomplish the tasks described herein. For example, the microprocessor should be able to feed data to the DAC subsystem, monitor the data progress, and interface with the CD drive to read raw audio data if desired. The controller 22 includes a display 51 in communication with the microprocessor by communication channel 64 . The display is preferably an alpha numeric display capable of displaying information regarding the CD being played, as well as the music sequences available in ROM 49 . In the preferred embodiment the display 51 is a multi character fluorescent display. Other displays may be used to convey information to the user. The controller also includes user controls 53 in communication with the micro processor 45 by communication channel 67 . In the preferred embodiment, the user control 53 includes a knob that can be rotated to scroll through the available selections, and pressed to select the displayed selection, which determines the music sequence the controller 22 will play. One skilled in the art will recognize that the user controls 53 can be any type of device that allows the user to interact with the controller 22 . For instance the user controls 53 could be a push button, keyboard, or touch screen. In the preferred embodiment, the display shows the titles of the music sequences available for play by the controller. The number of titles displayed at any one time depends upon the size of the display used. The user manipulates user controls 53 to change the titles displayed until the desired title is displayed and selected for play. The titles are obtained from the files stored in ROM 49 . In the preferred embodiment, the ROM 49 contains music sequences corresponding to a particular commercial CD. The individual music sequences generally correspond to the tracks present on the commercial CD. The volume ID for the CD, and the track number are preferably stored as meta events in the music sequence. Alternately, the Volume ID and track number can form part of the file name for the music sequence file. The ROM 49 may also include a file to associate the song titles of the music sequence with the volume ID and track numbers of the CD. Thus, the controller 22 can display the song titles on the display 51 corresponding to the music sequences available in ROM 49 . The music sequences are authored to the CD using standard authoring software such as a Digital Performer sold by Motu. During the authoring process, which is familiar to those skilled in the art, the music sequence is stored in a file as articulation or MIDI events. The timing or reference of the articulation events is based upon the audio rate or sample rate of the CD. FIG. 2 shows the relationship between an analog audio signal 70 , such as the audio output of the DAC subsystem, and the articulation events 71 of a corresponding music sequence 72 . One skilled in the art will recognize that the analog signal 70 is created from the conversion of the digital audio data having a sample rate of 44.1 kHz, and that the authoring software relates the meta events to the timing of the digital audio data. Thus, when the CD is played in the CD drive 40 , the microprocessor 45 can access the DAC subsystem 42 to determine how many samples have passed since the beginning of play to obtain an accurate time base. Having that information, the microprocessor 45 can send the articulation event to the piano 24 at the correct time. In the preferred embodiment, the piano 24 is a solenoid actuated system, and as such has an inherent delay between the time it receives a meta event and the sounding of the note on the piano 24 . In order to account for this delay, the microprocessor 45 sends the meta event to the piano 24 at a discrete time in advance of the timestamp of the meta event. In the preferred embodiment, the discrete time is 500 ms. Thus, the microprocessor 45 sends the midi event to the piano 500 ms earlier than called for by the timestamp associated with the event in order to achieve playing of the piano 24 in absolute synchronization with the CD. In operation, the system 20 generally operates as outlined herein. One skilled in the art will recognize that the operation may vary depending upon the particular embodiment. The user selects a ROM device, such as a CD card, containing the music sequence files authored for a particular CD. The user inserts the ROM device into the slot or interface 48 on the face of the controller 22 , allowing the microprocessor 45 to access the files on the ROM device. The user also places the desired CD into the CD drive 40 . The microprocessor accesses the files on the ROM 49 and displays the titles of music selections available on the display 51 . The titles are displayed one at a time. In order to advance to the next available title, the user manipulates a user control 53 , which in the preferred embodiment is a rotatable knob. Rotation of the knob scrolls through the available music selections. When the desired music selection appears on the display 51 , the user manipulates a user control 53 to start play, which in this embodiment involves pressing the knob. One skilled in the art will recognize that other types of controls or interfaces can be used. In response, the microprocessor 45 accesses ROM 49 and loads the selected music sequence along with its volume ID and track number in to RAM 47 . The microprocessor 45 then quires the CD drive to obtain the volume ID of the CD in the drive to determine if the volume ID of the CD in the CD drive 40 matches the volume ID loaded into RAM 47 . If the volume ID does not match, the microprocessor displays on the display 51 indicia such as “insert CD” or other instructions to the user to indicate that the CD in the CD drive 40 does not match the CD for the ROM device selected. If the volume ID does match, play of the CD audio data can begin. To play the digital audio data, the microprocessor 45 resets an internal time sequencer and instructs the CD drive 40 to send the digital audio data to the DAC subsystem 42 . The DAC subsystem 42 converts the digital audio data to an analog signal, which is then output to an amplifier 26 for play on speaker 28 . The DAC also provides the microprocessor 45 with the time progress of the digital audio data processed by sending the microprocessor 45 timing information from the DAC subsystem's 42 DMA progress status. Monitoring this information, the microprocessor 45 knows what time it is relative to the start of the playing of the CD audio data. The microprocessor advances this time by a discrete amount, preferably 500 ms and tracks the time in its internal time sequencer. As the time in the internal time sequencer progresses, the microprocessor issues meta events to the piano 24 via communications channel 35 , thus allowing play of the piano in absolute synchronization with the CD being played. The embodiments described herein are mere examples of the teachings of the invention. As such, they are not intended to limit the scope of the claimed invention.

The invention disclosed is a system for playing a music sequence such as a MIDI file in synchronization with a prerecorded CD. The synchronization is accomplished by using the digital media sample rate as a common time base for progression of the playing of the digital media and the music sequence.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This invention is a formal application of a provisional application, filed on Dec. 18, 2000, Serial No, 60/256,735 and a continuation application filed Sep. 19, 2001, Ser. No. 09/956,727. FILED OF INVENTION [0002] This invention relates to a new design of a soft inner enclosure for the carrying case of an external data storage device or other electronic devices for shock protection of the external data storage device or other electronic devices in their storage, carrying and operating mode. BACKGROUND OF INVENTION [0003] The need of an enclosure for the protection of a variety of devices against shock has been around for a long time. A brief search and analysis of the prior art revealed the following US patents: [0004] U.S. Pat. No. 4,786,121 (November 1988, by Lyons), titled computer protective enclosure, teaches the usage of outside panels with inner linings to acoustically isolate and additionally protect the stored computer. The outside panels, or covers, are made of rigid materials such as wood, plastic and metal. The inner linings are made of foam plastic with a space between the inner linings and the computer. Furthermore, the enclosure is intended for affixing to building construction members or other stationary objects for stability. [0005] U.S. Pat. No. 4,846,340 (July 1989, by Walther), titled shock proof carrying enclosure for musical instrument, teaches the usage of an enclosure for the shock proof storage and carrying of a musical instrument like cello. However, in this case, the enclosed musical instrument is already retained within a rigid case to begin with. Therefore, effectively, the protective structure for the musical instrument itself consists of an inner rigid case and an outer flexible enclosure. [0006] U.S. Pat. No. 5,010,988 (April 1991, by Brown), titled expandable shock protected carrying case, teaches the usage of a carrying case for a lap top computer, printers, facsimiles and the like where the carrying case comprises of functional elements like handle, shoulder strap, compartments and accessory pockets. The disclosed wall structure consists of at least three layers, that is, an outer shell, an inner shell and a three-ply shock protection structure sandwiched in between. The outer shell is made of a substantially rigid yet soft material. The disclosed carrying case looks to be primarily used when the enclosed device is in its non-operating mode. Thus, for example, thermally insulating materials and related structural design are employed there to protect the enclosed device from temperature extremes. [0007] U.S. Pat. No. 6,034,841 (March 2000, by Albrecht, Khanna, Kumar and Sri-Jayantha), titled disk drive with composite sheet metal and encapsulated plastic, describes the usage of a metal base with integrally molded plastic peripheral flanges plus elastomeric comer bumpers for shock protection. As described, except for the elastomeric comer bumpers, all the other enclosure pieces are made of rigid material. [0008] As described in a pending application filed earlier by the inventor, a soft enclosure design for an external data storage device or other electronic devices in their storage, carrying and operating mode is disclosed. The inside shock absorbing layer of the soft enclosure design, now called inner enclosure for simplicity, provides many functions. Some examples of the functions are shock protection, heat dissipation, fire retardation, shielding against radio frequency interference, prevention of build up of static electricity and prevention of dirt penetration into the interior of the enclosure. This invention deals with a more specific design of the inner enclosure with additional merits. For clarity, it is remarked that the inner enclosure is also commonly referred to as the inner lining for a carrying case. SUMMARY OF INVENTION [0009] The current invention is conceived to realize a more specific design of the inner enclosure, or the inner lining for a carrying case, of an external data storage device with additional merits. Specifically, it is an objective of this invention to provide an inner enclosure for an external data storage device whereby the function of shock protection for the data storage device is achieved by using a minimum amount of materials thus saving manufacturing cost and reducing the associated product weight. [0010] It is another objective of this invention to provide an inner enclosure for an external data storage device whereby improved heat dissipation for the data storage device is achieved by using a minimum amount of materials thus saving manufacturing cost and reducing the associated product weight. [0011] A third objective of this invention is to provide an inner enclosure for an external data storage device whereby the functions of fire retardation, shielding against radio frequency interference and prevention of build up of static electricity are achieved with a selection of specific materials for the inner enclosure. [0012] Accordingly, the invention disclose a new design of the inner enclosure for the carrying case of, but without limitation to, an external data storage device as mentioned in the said prior application. The inner enclosure is made of a soft shock absorbing material and provides for a snug fit and an all around shock protection for the enclosed data storage device in both non-operating and operating modes. The inner enclosure consists of a device compartment and a removable cover. Once the inner enclosure is completely closed within an outer enclosure, the inner enclosure will provide a snug fit to the enclosed device all around. For good shock absorption while using a minimum amount of material, the inner surface of the inner enclosure is constructed with an array of substantially evenly spaced miniature columns called Micro Shock Absorber (MSA). In addition to shock protection, the MSA also provides air circulation to the enclosed storage device by creating a thin air space between the device and the inner enclosure. As needed, the material of the inner enclosure can be selected to be fire retardant, shielding against radio frequency interference, preventing build up of static electricity, allowing better heat dissipation from the data storage device while preventing dirt penetration into the interior of the enclosure. BRIEF DESCRIPTION OF DRAWINGS [0013] The invention is explained in full detail with the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein: [0014] [0014]FIG. 1 is one perspective illustration of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device; [0015] [0015]FIG. 2 is one more perspective illustration of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device; [0016] FIGS. 3 A-C are perspective illustrations of the current invention wherein two soft inner enclosures, or alternatively called inner linings, are employed to enclose a storage device; [0017] [0017]FIG. 4 is a perspective illustration of the current invention wherein the details of the MSA structure and its associated design parameters are shown; [0018] FIGS. 5 A-B are comparison of the wall structure between a traditional and the current design of the inner enclosure with design parameters illustrating the benefit of materials saving with the current invention; [0019] [0019]FIG. 6 illustrates an additional embodiment of the current invention wherein a set of micro venting slots are added to the wall structure of the current invention with MSA for further improved heat dissipation; [0020] FIGS. 7 A-B are additional perspective illustrations of the current invention wherein a fully enclosed storage device, within two soft inner enclosures with MSA, similar to that illustrated in FIG. 3C is progressively shown to be loaded into a soft outside enclosure; and [0021] FIGS. 8 A-B are the final perspective illustrations of the current invention wherein the fully enclosed storage device from FIG. 7B is progressively shown to be fully enclosed with the closure of a soft device cover and a soft connector cover. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0022] [0022]FIG. 1 and FIG. 2 are perspective illustrations of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device. FIG. 1 illustrates, with two arrows, the progressive enclosure of a storage device 1 with a storage device interface connector 2 and an associated rigid connector interchanger 70 . The wall material of the storage device 1 is usually made of metal to house the precision mechanism inside. The storage device interface connector 2 , when hooked up, through the associated rigid connector interchanger 70 , with the corresponding mating connector of a computer not shown here, would provide all the necessary electrical power and interface signals to insure proper operation of the storage device 1 . As shown, the storage device 1 will generally be housed between a rigid top cover 30 and a rigid bottom cover 40 with a set of mounting screws 50 . The finished product is illustrated in FIG. 2. Usually these rigid covers are made of plastics or metal. Thus, the enclosed storage device 1 is still very susceptible to shock damage as the rigid covers do not provide any damping protection against shock. [0023] [0023]FIG. 3A, FIG. 3B and FIG. 3C are perspective illustrations of the current invention wherein two soft inner enclosures, or alternatively called inner linings, are employed to enclose a storage device. The two soft inner enclosures are, as shown in FIG. 3A, a soft top inner enclosure 3 and a soft bottom inner enclosure 4 . The storage device to be enclosed by the soft top inner enclosure 3 and the soft bottom inner enclosure 4 is the storage device 1 with a storage device interface connector 2 . The storage device interface connector 2 , when hooked up with the corresponding mating connector from a computer not shown here, would provide all the necessary electrical power and interface signals to insure proper operation of the storage device 1 . Many storage device 1 , such as external or portable hard drives, optical storage devices or computers with built in magnetic and optical storage devices, can be easily damaged when it is dropped accidentally. Thus, the soft top inner enclosure 3 and the soft bottom inner enclosure 4 are used together to provide protection for the storage device 1 in both operating and non-operating modes. The soft top inner enclosure 3 consists of a soft top inner enclosure base 9 c whose inside surface has a set of soft top enclosure MSA 17 which will be described in more detail later. The soft bottom inner enclosure 4 consists of a soft bottom inner enclosure base 9 a , four soft bottom inner enclosure side walls 9 d with a connector access slot 9 b located on one of the soft bottom inner enclosure side walls 9 d . Like the soft top inner enclosure 3 , the soft bottom inner enclosure base 9 a also has a set of soft bottom enclosure MSA 16 located on its inside surface which will also be described in more detail later. Thus, following the direction of the arrows, the soft top inner enclosure 3 and the soft bottom inner enclosure 4 will provide a snug fit to the enclosed storage device 1 all around except for the mechanical accessibility to the storage device interface connector 2 through the connector access slot 9 b of the soft bottom inner enclosure 4 . This is illustrated in FIG. 3B and FIG. 3C. [0024] [0024]FIG. 4 shows more details of the soft top inner enclosure 3 and the soft bottom inner enclosure 4 . To provide for sufficient shock protection with the proper range of softness, or durometer, the selected material for the inner enclosure is soft Microcellular Urethane (trade name: PORON), Polyurethane or other material with similar properties. For further enhancement of shock protection, the inside surfaces of both inner enclosures 3 and 4 are constructed with a set of substantially evenly spaced small columns of MSA protrusions. These are soft top enclosure MSA 17 for the soft top inner enclosure 3 and the soft bottom enclosure MSA 16 for the soft bottom inner enclosure 4 . As the MSA and the inner enclosure body are made of the same material, the MSA can be easily casted or molded as part of the enclosure in volume production. Furthermore, as neither the MSA nor the inner enclosure body requires high dimensional accuracy, the need of expensive tooling for the cast or mold is eliminated. [0025] The amount of shock protection provided by the MSA depends primarily on the following parameters: the durometer of the Microcellular Urethane, the MSA base thickness T, the MSA diameter D, the MSA height H, the MSA pitch P as well as the density of the enclosed storage device 1 . In general, the following qualitative design guidelines were discovered: (1) lower durometer of the inner enclosure base material yields higher shock protection; (2) higher MSA base thickness T yields higher shock protection; (3) larger MSA diameter D yields higher shock protection; (4) larger MSA height H yields higher shock protection; (5) lower MSA pitch P yields higher shock protection and (6) lower density of the enclosed storage device 1 allows higher shock protection. [0026] However, in practice, the complexity of the involved quantitative functional relationship amongst the above design parameters is found to be too complicated to warrant a mathematical treatment. Instead, an empirical design must be reached through a set of parametric experiments following the above qualitative design guidelines. As a quantitative example of this invention, we have made the following findings. [0027] A typical 2.5 inch hard disk storage device can be adequately shock protected from a drop height of up to 4 feet onto a hard surface with an MSA structure of the following parametric design: (1) inner enclosure base material is Microcellular Urethane; (2) durometer of the inner enclosure base material is 30 durometer; (3) MSA base thickness T=6.4 mm; (4) MSA diameter D=7 mm; (5) MSA height H=4 mm height; (6) MSA pitch P=17 mm. [0028] Another point to be made here is that, given the aforementioned complexity of the functional relationship among the design parameters, multiple combinations within a range of parameters exist for the same desired shock protection. For example, in the above case, an MSA diameter D from 6 mm to 8 mm and an MSA height H from 4 mm to 5 mm would all produce similar shock protection. [0029] A subtle but important benefit of the current invention is illustrated in FIG. 5A and FIG. 5B. FIG. 5A represents a prior art inner enclosure wall structure 20 which is plain while FIG. 5B represents the current invention with the MSA wall structure 21 optimized for a minimum overall thickness of the MSA structure T+H, for a specified amount of shock protection. While the prior art inner enclosure wall structure 20 has the same overall wall thickness S=T+H as the current invention, it was found that the prior art design can not provide the specified amount of shock protection as does the current invention. The reason is that, upon impact of the enclosed storage device with an external object, the numerous soft bottom enclosure MSA 16 of the current invention act as an initial spacer during the first stage of the shock absorption process where most of the associated kinetic energy is dissipated. That is, only the soft bottom enclosure MSA 16 go through related geometric deformation to dissipate the kinetic energy while the enclosed storage device stays free of contact with the soft bottom inner enclosure base 9 a . While the storage device still contacts the soft bottom inner enclosure base 9 a during the second, or last, stage of the shock absorption process, by this time the remaining kinetic energy to be dissipated is significantly lower than its value during the first stage. In summary, given the same specified amount of shock protection and the same overall wall thickness, the net kinetic energy to be dissipated upon impact by the enclosed storage device with the current invention would be significantly less than that with a traditional prior art design. Or equivalently, given the same specified amount of shock protection, the current invention will provide a design which has a significantly less overall wall thickness than the traditional design. This translates into an advantage of size and weight reduction with the current invention. Furthermore, given the MSA structure, the net volume occupied by the shock absorbing material is significantly less than that enclosed in the overall wall thickness T+H, this translates into another advantage of weight reduction with the current invention. A third advantage of the current invention is that, upon closure of the soft top inner enclosure 3 and the soft bottom inner enclosure 4 , a thin air space is formed between the enclosed storage device 1 and the inner enclosure with MSA wall structure 21 . The thin air space thus provides the function of air circulation resulting in a more uniform distribution of heat from the storage device 1 for a more efficient heat dissipation to the outside ambient. [0030] [0030]FIG. 6 illustrates an additional embodiment of the current invention wherein the inner enclosure with MSA wall structure 21 has a set of substantially evenly spaced micro venting slots 22 cut through its wall to further improve heat dissipation to the outside ambient. Of course, the cross section of these venting features does not have to be a slot. For example, it can be a circle, an ellipse or any other shape as long as easy manufacturability is maintained. [0031] Finally, Microcellular Urethane, one of the selected material for the inner enclosure with MSA, possesses additional physical properties which are important or beneficial to the enclosed storage device. Microcellular Urethane has low memory effect, which is important for the preservation of the MSA geometry after long termed usage or storage of the storage device. Microcellular Urethane is reasonably heat conductive which helps the dissipation of heat from the storage device. It does not accumulate static electricity thus provides good ESD protection for the storage device. It is fire retardant with UL-approval for a safe product. It can be metallically coated to shield against EMI/RFI for reliable data transfer. [0032] [0032]FIG. 7A and FIG. 7B are additional perspective illustrations of the current invention wherein a storage device is fully enclosed with a set of soft inner enclosures, similar to that shown in FIG. 3C, the storage device is progressively shown to be loaded into a soft outside enclosure 8 . Following the direction of the arrows in FIG. 7A, the now enclosed storage device 1 is first loaded into the soft outside enclosure 8 . Afterwards, the storage device 1 , now enclosed in both inner and outer soft enclosures with shock protection, is shown in FIG. 7B. Notice that the mechanical accessibility to the interface pins of the storage device 1 is maintained through the corresponding connector access slot 9 b of the soft bottom inner enclosure 4 and the connector access slot 15 of the soft outside enclosure 8 . [0033] [0033]FIG. 8A and FIG. 8B are the final perspective illustrations of the current invention wherein the enclosed storage device 1 from FIG. 7B is progressively shown to be fully enclosed like a carrying bag in the non-operating state of the storage device 1 with the closure of a soft device cover and a soft connector cover. Following the right hand arrow of FIG. 8A, the soft outside enclosure device cover 12 will be closed with the movement of the zipper mechanism consisting of two soft outside enclosure zippers 10 and an outside enclosure zipper handle 11 . Finally, following the left hand arrow of FIG. 8A, the soft outside enclosure connector cover 13 will be closed with the mating of a velcro hook pad 14 a to a velcro loop pad 14 b . The final enclosure in the form of a carrying bag is illustrated in FIG. 8B. [0034] In summary, as illustrated above, a first advantage of the current invention is that, given the same specified amount of shock protection, the current invention provides an inner enclosure for a storage device whose overall wall thickness is significantly less than that of a traditional design. The net result is a size and weight reduction of the product. [0035] The second advantage of the current invention is that, with the MSA geometry, the net volume occupied by the shock absorbing material is significantly less than that enclosed within the overall wall thickness. This means additional cost and weight reduction of the product. [0036] A third advantage of the current invention is that a thin air space is formed between the enclosed storage device and the inner enclosure with the MSA wall structure. The thin air space thus provides the function of air circulation resulting in a more uniform distribution of heat from the storage device for a correspondingly more efficient heat dissipation to the outside ambient. [0037] A fourth advantage of the current invention is that a set of micro venting slots are provided on the MSA wall structure to further improve heat dissipation from the storage device to the outside ambient. [0038] A fifth advantage of the current invention is that the selected base material for the inner enclosure has a set of physical properties which result in the following benefits such as preservation of the MSA geometry after long termed usage or storage of the storage device; improved heat dissipation from the storage device; good ESD protection for the storage device; fire retardation with UL-approval and shielding against EMIRFI for reliable data transfer. [0039] In conclusion, an improved inner enclosure, or alternatively called inner lining, with MSA has been described for an external storage device providing shock protection, improved heat dissipation plus a set of additional functions while reducing the cost, size and weight of the product. The invention has been described using exemplary preferred embodiments. However, for those skilled in this field the preferred embodiments can be easily adapted and modified to suit additional applications without departing from the spirit and scope of this invention. Thus, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements based upon the same operating principle. The scope of the claims, therefore, should be accorded the broadest interpretations so as to encompass all such modifications and similar arrangements.

An improved soft inside enclosure for shock protection of a variety of external electronic and computer peripheral comprises a set of substantially evenly spaced small columns of Micro Shock Absorber (MSA) protrusions that are integrated on the inside surfaces of the soft inside enclosure. Additionally, the base wall of the MSA structure can include a set of micro venting features for the improvement of heat dissipation from the enclosed devices to the ambient. A number of specific candidate materials are also presented for the construction of the soft inside enclosure with the MSA structure. A method for the systematic and experimental determination of a specific design of the MSA structure based on its durometer, thickness, diameter, column height, and pitch are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Pursuant to 35 U.S.C. § 119(e), this application claims the benefit of earlier filing date and right of priority to U.S. Provisional Application No. 60/599,590, filed on Aug. 5, 2004, U.S. Provisional Application No. 60/600,244, filed on Aug. 9, 2004, and U.S. Provisional Application No. 60/601,267, filed on Aug. 12, 2004, the contents of which are hereby incorporated by reference herein in their entirety. FIELD OF THE INVENTION [0002] The present invention relates to cell selection in a wireless communication system, and more particularly, to interrupting use of a frequency layer convergence scheme which favors the selection of a cell on a preferred frequency of a joined point-to-multipoint service. BACKGROUND OF THE INVENTION [0003] Recently, mobile communication systems have developed remarkably, but for high capacity data communication services, the performance of mobile communication systems cannot match that of existing wired communication systems. Accordingly, technical developments for IMT-2000, which is a communication system allowing high capacity data communications, are being made and standardization of such technology is being actively pursued among various companies and organizations. [0004] A universal mobile telecommunication system (UMTS) is a third generation mobile communication system that has evolved from a European standard known as Global System for Mobile communications (GSM). The UMTS aims to provide improved mobile communication service based on a GSM core network and wideband code division multiple access (W-CDMA) wireless connection technology. [0005] In December 1998, ETSI of Europe, ARIB/TTC of Japan, T1 of the United States, and TTA of Korea formed a Third Generation Partnership Project (3GPP) for creating the detailed specifications of the UMTS technology. [0006] Within the 3GPP, in order to achieve rapid and efficient technical development of the UMTS, five technical specification groups (TSG) have been created for performing the standardization of the UMTS by considering the independent nature of the network elements and their operations. [0007] Each TSG develops, approves, and manages the standard specification within a related region. Among these groups, the radio access network (RAN) group (TSG-RAN) develops the standards for the functions, requirements, and interface of the UMTS terrestrial radio access network (UTRAN), which is a new radio access network for supporting W-CDMA access technology in the UMTS. [0008] FIG. 1 illustrates an exemplary basic structure of a general UMTS network. As shown in FIG. 1 , the UMTS is roughly divided into a mobile terminal (or user equipment: UE) 10 , a UTRAN 100 , and a core network (CN) 200 . [0009] The UTRAN 100 includes one or more radio network sub-systems (RNS) 110 , 120 . Each RNS 110 , 120 includes a radio network controller (RNC) 111 , and a plurality of base stations or Node-Bs 112 , 113 managed by the RNC 111 . The RNC 111 handles the assigning and managing of radio resources, and operates as an access point with respect to the core network 200 . [0010] The Node-Bs 112 , 113 receive information sent by the physical layer of the terminal through an uplink, and transmit data to the terminal through a downlink. The Node-Bs 112 , 113 , thus, operate as access points of the UTRAN 100 for the terminal. [0011] A primary function of the UTRAN 100 is forming and maintaining a radio access bearer (RAB) to allow communication between the terminal and the core network 200 . The core network 200 applies end-to-end quality of service (QoS) requirements to the RAB, and the RAB supports the QoS requirements set by the core network 200 . As the UTRAN 100 forms and maintains the RAB, the QoS requirements of end-to-end are satisfied. The RAB service can be further divided into an Iu bearer service and a radio bearer service. The Iu bearer service supports a reliable transmission of user data between boundary nodes of the UTRAN 100 and the core network 200 . [0012] The core network 200 includes a mobile switching center (MSC) 210 and a gateway mobile switching center (GMSC) 220 connected together for supporting a circuit switched (CS) service, and a serving GPRS support node (SGSN) 230 and a gateway GPRS support node 240 connected together for supporting a packet switched (PS) service. [0013] The services provided to a specific terminal are roughly divided into the circuit switched (CS) services and the packet switched (PS) services. For example, a general voice conversation service is a circuit switched service, while a Web browsing service via an Internet connection is classified as a packet switched (PS) service. [0014] For supporting circuit switched services, the RNCs 111 are connected to the MSC 210 of the core network 200 , and the MSC 210 is connected to the GMSC 220 that manages the connection with other networks. [0015] For supporting packet switched services, the RNCs 111 are connected to the SGSN 230 and the GGSN 240 of the core network 200 . The SGSN 230 supports the packet communications going toward the RNCs 111 , and the GGSN 240 manages the connection with other packet switched networks, such as the Internet. [0016] Various types of interfaces exist between network components to allow the network components to transmit and receive information to and from each other for mutual communication therebetween. An interface between the RNC 111 and the core network 200 is defined as an Iu interface. In particular, the Iu interface between the RNCs 111 and the core network 200 for packet switched systems is defined as “Iu-PS,” and the Iu interface between the RNCs 111 and the core network 200 for circuit switched systems is defined as “Iu-CS.” [0017] FIG. 2 illustrates a structure of a radio interface protocol between the terminal and the UTRAN according to the 3GPP radio access network standards. [0018] As shown in FIG. 2 , the radio interface protocol has horizontal layers comprising a physical layer, a data link layer, and a network layer, and has vertical planes comprising a user plane (U-plane) for transmitting user data and a control plane (C-plane) for transmitting control information. [0019] The user plane is a region that handles traffic information of the user, such as voice or Internet protocol (IP) packets, while the control plane is a region that handles control information for an interface of a network, maintenance and management of a call, and the like. [0020] The protocol layers in FIG. 2 can be divided into a first layer (L 1 ), a second layer (L 2 ), and a third layer (L 3 ) based on three lower layers of an open system interconnection (OSI) standard model. Each layer will be described in more detail as follows. [0021] The first layer (L 1 ), namely, the physical layer, provides an information transfer service to an upper layer by using various radio transmission techniques. The physical layer is connected to an upper layer called a medium access control (MAC) layer, via a transport channel. The MAC layer and the physical layer send and receive data with one another via the transport channel. [0022] The second layer (L 2 ) includes a MAC layer, a radio link control (RLC) layer, a broadcast/multicast control (BMC) layer, and a packet data convergence protocol (PDCP) layer. [0023] The MAC layer provides an allocation service of the MAC parameters for allocation and re-allocation of radio resources. The MAC layer is connected to an upper layer called the radio link control (RLC) layer, via a logical channel. [0024] Various logical channels are provided according to the kind of transmitted information. In general, when information of the control plane is transmitted, a control channel is used. When information of the user plane is transmitted, a traffic channel is used. A logical channel may be a common channel or a dedicated channel depending on whether the logical channel is shared. Logical channels include a dedicated traffic channel (DTCH), a dedicated control channel (DCCH), a common traffic channel (CTCH), a common control channel (CCCH), a broadcast control channel (BCCH) and a paging control channel (PCCH) or a Shared Channel Control Channel (SHCCH). The BCCH provides information including information utilized by a terminal to access a system. The PCCH is used by the UTRAN to access a terminal. [0025] A Multimedia Broadcast/Multicast Service (MBMS or “MBMS service”) refers to a method of providing streaming or background services to a plurality of UEs using a downlink-dedicated MBMS radio bearer that utilizes at least one of point-to-multipoint and point-to-point radio bearer. One MBMS service includes one or more sessions and MBMS data is transmitted to the plurality of terminals through the MBMS radio bearer only while the session is ongoing. [0026] As the name implies, an MBMS may be carried out in a broadcast mode or a multicast mode. The broadcast mode is for transmitting multimedia data to all UEs within a broadcast area, for example the domain where the broadcast is available. The multicast mode is for transmitting multimedia data to a specific UE group within a multicast area, for example the domain where the multicast service is available. [0027] For purposes of MBMS, additional traffic and control channels exist. For example, an MCCH (MBMS point-to-multipoint Control Channel) is used for transmitting MBMS control information while an MTCH (MBMS point-to-multipoint Traffic Channel) is used for transmitting MBMS service data. [0028] The different logical channels that exist are listed below: [0000] [0029] The MAC layer is connected to the physical layer by transport channels and can be divided into a MAC-b sub-layer, a MAC-d sub-layer, a MAC-c/sh sub-layer, and a MAC-hs sub-layer according to the type of transport channel to be managed. [0030] The MAC-b sub-layer manages a BCH (Broadcast Channel), which is a transport channel handling the broadcasting of system information. The MAC-d sub-layer manages a dedicated channel (DCH), which is a dedicated transport channel for a specific terminal. Accordingly, the MAC-d sub-layer of the UTRAN is located in a serving radio network controller (SRNC) that manages a corresponding terminal, and one MAC-d sub-layer also exists within each terminal (UE). [0031] The MAC-c/sh sub-layer manages a common transport channel, such as a forward access channel (FACH) or a downlink shared channel (DSCH), which is shared by a plurality of terminals, or in the uplink the Radio Access Channel (RACH). In the UTRAN, the MAC-c/sh sub-layer is located in a controlling radio network controller (CRNC). As the MAC-c/sh sub-layer manages the channel being shared by all terminals within a cell region, a single MAC-c/sh sub-layer exists for each cell region. Also, one MAC-c/sh sublayer exists in each terminal (UE). Referring to FIG. 3 , possible mapping between the logical channels and the transport channels from a UE perspective is shown. Referring to FIG. 4 , possible mapping between the logical channels and the transport channels from a UTRAN perspective is shown. [0032] The RLC layer supports reliable data transmissions, and performs a segmentation and concatenation function on a plurality of RLC service data units (RLC SDUs) delivered from an upper layer. When the RLC layer receives the RLC SDUs from the upper layer, the RLC layer adjusts the size of each RLC SDU in an appropriate manner upon considering processing capacity, and then creates certain data units with header information added thereto. The created data units are called protocol data units (PDUs), which are then transferred to the MAC layer via a logical channel. The RLC layer includes a RLC buffer for storing the RLC SDUs and/or the RLC PDUs. [0033] The BMC layer schedules a cell broadcast message (referred to as a ‘CB message’, hereinafter) received from the core network, and broadcasts the CB messages to terminals located in a specific cell(s). The BMC layer of the UTRAN generates a broadcast/multicast control (BMC) message by adding information, such as a message ID (identification), a serial number, and a coding scheme to the CB message received from the upper layer, and transfers the BMC message to the RLC layer. The BMC messages are transferred from the RLC layer to the MAC layer through a logical channel, i.e., the CTCH (Common Traffic Channel). The CTCH is mapped to a transport channel, i.e., a FACH, which is mapped to a physical channel, i.e., a S-CCPCH (Secondary Common Control Physical Channel). [0034] The PDCP (Packet Data Convergence Protocol) layer, as a higher layer of the RLC layer, allows the data transmitted through a network protocol, such as an IPv4 or IPv6, to be effectively transmitted on a radio interface with a relatively small bandwidth. To achieve this, the PDCP layer reduces unnecessary control information used in a wired network, a function called header compression. [0035] A radio resource control (RRC) layer is located at a lowermost portion of the L3 layer. The RRC layer is defined only in the control plane, and handles the control of logical channels, transport channels, and physical channels with respect to setup, reconfiguration, and release or cancellation of radio bearers (RBs). The radio bearer service refers to a service provided by the second layer (L 2 ) for data transmission between the terminal and the UTRAN. In general, the setup of the radio bearer refers to the process of defining the characteristics of a protocol layer and a channel required for providing a specific data service, as well as respectively setting detailed parameters and operation methods. [0036] The RLC layer can belong to the user plane or to the control plane depending upon the type of layer connected at the upper layer of the RLC layer. That is, if the RLC layer receives data from the RRC layer, the RLC layer belongs to the control plane. Otherwise, the RLC layer belongs to the user plane. [0037] The different possibilities that exist for the mapping between the radio bearers and the transport channels are not always possible. The UE/UTRAN deduces the possible mapping depending on the UE state and the procedure that the UE/UTRAN is executing. The different states and modes are explained in more detail below. [0038] The different transport channels are mapped onto different physical channels. For example, the RACH transport channel is mapped on a given PRACH, the DCH can be mapped on the DPCH, the FACH and the PCH can be mapped on the S-CCPCH, the DSCH is mapped on the PDSCH and so on. The configuration of the physical channels is given by an RRC signaling exchange between the RNC and the UE. [0039] The RRC mode refers to whether there exists a logical connection between the RRC of the terminal and the RRC of the UTRAN. If there is a connection, the terminal is said to be in RRC connected mode. If there is no connection, the terminal is said to be in idle mode. Because an RRC connection exists for terminals in RRC connected mode, the UTRAN can determine the existence of a particular terminal within the unit of cells, for example which cell or set of cells the RRC connected mode terminal is in, and which physical channel the UE is listening to. Thus, the terminal can be effectively controlled. [0040] In contrast, the UTRAN cannot determine the existence of a terminal in idle mode. The existence of idle mode terminals can only be determined by the core network. Specifically, the core network can only detect the existence of idle mode terminals within a region that is larger than a cell, such as a location or a routing area. Therefore, the existence of idle mode terminals is determined within large regions. In order to receive mobile communication services such as voice or data, the idle mode terminal must move or change into the RRC connected mode. The possible transitions between modes and states are shown in FIG. 5 . [0041] A UE in RRC connected mode can be in different states, such as a CELL_FACH state, a CELL_PCH state, a CELL_DCH state or a URA_PCH state. Depending on the states, the UE listens to different channels. For example a UE in CELL_DCH state will try to listen (amongst others) to DCH type of transport channels, which comprises DTCH and DCCH transport channels, and which can be mapped to a certain DPCH. The UE in CELL_FACH state will listen to several FACH transport channels which are mapped to a certain S-CCPCH physical channel. The UE in PCH state will listen to the PICH channel and to the PCH channel, which is mapped to a certain S-CCPCH physical channel. [0042] The UE also carries out different actions depending on the state. For example, based on different conditions, a UE in CELL_FACH will start a CELL Update procedure each time the UE changes from the coverage of one cell into the coverage of another cell. The UE starts the CELL Update procedure by sending to the NodeB a Cell Update message to indicate that the UE has changed its location. The UE will then start listening to the FACH. This procedure is additionally used when the UE comes from any other state to CELL_FACH state and the UE has no C-RNTI available, such as when the UE comes from the CELL_PCH state or CELL_DCH state, or when the UE in CELL_FACH state was out of coverage. [0043] In the CELL_DCH state, the UE is granted dedicated radio resources, and may additionally use shared radio resources. This allows the UE to have a high data rate and efficient data exchange. However, the radio resources are limited. It is the responsibility of the UTRAN to allocate the radio resources amongst the UEs such that they are efficiently used and ensure that the different UEs obtain the quality of service required. [0044] A UE in CELL_FACH state has no dedicated radio resources attributed, and can only communicate with the UTRAN via shared channels. Thus, the UE consumes few radio resources. However, the data rate available is very limited. Also, the UE needs to permanently monitor the shared channels. Thus, UE battery consumption is increased in the case where the UE is not transmitting. [0045] A UE in CELL_PCH/URA_PCH state only monitors the paging channel at dedicated occasions, and therefore minimizes the battery consumption. However, if the network wishes to access the UE, it must first indicate this desire on the paging occasion. The network may then access the UE, but only if the UE has replied to the paging. Furthermore, the UE can only access the network after performing a Cell Update procedure which introduces additional delays when the UE wants to send data to the UTRAN. [0046] Main system information is sent on the BCCH logical channel, which is mapped on the P-CCPCH (Primary Common Control Physical Channel). Specific system information blocks can be sent on the FACH channel. When the system information is sent on the FACH, the UE receives the configuration of the FACH either on the BCCH that is received on the P-CCPCH or on a dedicated channel. The P-CCPCH is sent using the same scrambling code as a P-CPICH (Primary Common Pilot Channel), which is the primary scrambling code of the cell. Each channel uses a spreading code as commonly done in WCDMA (Wideband Code Division Multiple Access) systems. Each code is characterized by its spreading factor (SF), which corresponds to the length of the code. For a given spreading factor, the number of orthogonal codes is equal to the length of the code. For each spreading factor, the given set of orthogonal codes, as specified in the UMTS system, are numbered from 0 to SF-1. Each code can thus be identified by giving its length (i.e. spreading factor) and the number of the code. The spreading code that is used by the P-CCPCH is always of a fixed spreading factor 256 and the number is the number 1. The UE knows about the primary scrambling code either by information sent from the network on system information of neighboring cells that the UE has read, by messages that the UE has received on the DCCH channel, or by searching for the P-CPICH, which is sent using the fixed SF 256 and the spreading code number 0, and which transmits a fixed pattern. [0047] The system information comprises information on neighboring cells, configuration of the RACH and FACH transport channels, and the configuration of MCCH, which is a channel dedicated for MBMS service. When the UE has selected a cell (in CELL_FACH, CELL_PCH or URA_PCH state), the UE verifies that it has valid system information. [0048] The system information is organized in SIBs (system information blocks), a MIB (Master information block) and scheduling blocks. The MIB is sent very frequently and provides timing information of the scheduling blocks and the different SIBs. For SIBs that are linked to a value tag, the MIB also contains information on the last version of a part of the SIBs. SIBs that are not linked to a value tag are linked to an expiration timer. The SIBs linked to an expiration timer become invalid and need to be reread if the time of the last reading of the SIB is larger than an expiration timer value. The SIBs linked to a value tag are only valid if they have the same value tag as a value tag broadcast in the MIB. Each block has an area scope of validity, such as a Cell, a PLMN (Public Land Mobile Network) or an equivalent PLMN, which signifies on which cells the SIB is valid. A SIB with the area scope “Cell” is valid only for the cell in which it has been read. A SIB with the area scope “PLMN” is valid in the whole PLMN. A SIB with the area scope “equivalent PLMN” is valid in the whole PLMN and equivalent PLMN. [0049] According to the 3GPP standard, a UE in CELL_PCH, URA_PCH or CELL_FACH state, or in idle mode shall constantly try to select/reselect a suitable cell (for non-emergency calls) or acceptable cell (for emergency calls). In idle mode, when the UE has selected a cell, the UE is commonly referred to as “camping” on the cell. In RRC connected mode, when the UE is in CELL_PCH, URA_PCH, or CELL_FACH state, the UE is simply referred to as having “selected” a cell. [0050] To facilitate the cell reselection, the network transmits in the system information lists of neighboring cells. The lists of neighboring cells identify available cells the UE should measure and compare to the cell the UE has currently selected or the cell the UE camps on. The available cells may be on the same frequency, on other frequencies or on other Radio Access Technologies (RATs) such as GSM. The list of cells, and evtl. cells that the UE discovers itself are used as candidates for the cell reselection. [0051] One part of the cell selection/reselection process is based on measurements of the quality of the different cells that are part of the neighboring cell list that are candidates for cell reselection. A cell may or may not be part of a hierarchical cell structure (HCS). This is defined in the system information of the given cell. In case of the hierarchical cell structure, each cell has a given priority. Depending on whether the cell is part of the hierarchical cell structure or not, the cell selection procedure changes. [0052] To decide which of the candidate cells to reselect, the UE measures the quality of the neighboring cells. The UE uses a given formula to establish a ranking criteria R of all candidate cells. The formula is based on measurements on the CPICH/P-CCPCH and on information received in the system information of the candidate cell. The criterion R corresponds to a positive or negative value. The R value may be calculated by the following, wherein R S is the R value for the serving cell R N is the R value for neighboring cells: [0000] R s = Q meas , s + Qhyst s + Qoffmbms R n = Q meas , n − Qoffset s,n + Qoffmbms − TO n * (1 − L n ) TO n = TEMP_OFFSET n * W(PENALTY_TIME n − T n ) L n = 0 if HCS_PRIO n = HCS_PRIO s L n = 1 if HCS_PRIO n <> HCS_PRIO s W(x) = 0 for x < 0 W(x) = 1 for x >= 0 [0053] The signaled value Qoffmbms is only applied to those cells (serving or neighboring) belonging to an MBMS Preferred Frequency (i.e., where a frequency convergence scheme is applied). Qmeas gives the quality value of the received signal derived from the averaged CPICH Ec/No or CPICH RSCP for FDD cells, from the averaged P-CCPCH RSCP for TDD cells and from the averaged received signal level for GSM cells. For FDD cells, the measurement that is used to derive the quality value is indicated in System Information. [0054] The parameters Qhyst, Qoffsets,n, Qoffmbms, TEMP_OFFSET and PENALTY_TIME are signaled on System information. The timer T is started and stopped for each cell depending on the radio quality of the cell. [0055] If a hierarchical cell structure (HCS) is used, then a criteria H is defined. The H criterion is a positive or negative value and is calculated based on information sent in the system information and on measurements from the CPICH/P-CPCCH of the candidate cell. In the hierarchical cell structure, a cell may have a different priority. The H criterion is calculated according to the following formula: [0000] H s =Q meas,s −Qhcs s [0000] H n =Q meas,n −Qhcs n −TO n *L n [0056] TO n and LN, Q meas,s and Q meas,n are defined similarly to the above definition. The aim of such a cell structure is to cover in the same area users that have a low mobility as well as users with a high mobility. To optimize capacity, small-sized cells are preferred to accommodate as many cells as possible. Accordingly, this enables having a maximum number of users in a given area. [0057] However, for users that move quickly, it is preferable to have large-sized cells to reduce the number of cell changes as the UE moves. To distinguish between large-sized and small-sized cells, different priorities are attributed to the cell. The UE tends to select cells with the highest priority. This generally corresponds to small-sized cells, except when the UE is moving quickly. The H criterion is used in the 3GPP standard to take into account the priority. However, when the UE detects that it is moving quickly (i.e. by detecting that the UE reselects cells often), the UE ceases using the H criteria and no longer takes into account the priority level of the cell. The UE is then said to be in a “high mobility state”. [0058] A selection criterion S checks whether the received quality of the candidate cell is sufficient. To do so the, UE measures Q qualmeas , which expresses the E c /N 0 of the CPICH of the candidate cell (only for FDD cells). The UE also measures Q rxlevmeas , which evaluates the RSCP (Received Signal Code Power) of the CPICH of the candidate cell for FDD cells and the P-CCPCH of the candidate cell for TDD cells. The UE uses these values in an algorithm, together with information received in the system information of the candidate cell, to calculate the S value. If the S value is higher than 0, the selection criterion S of the cell is fulfilled. Otherwise, it is not fulfilled. [0059] Apart from the criteria R, H and S explained above, other criteria might determine which cell the UE can select. The information on these criteria is given to the UE as “cell access restrictions”, which are broadcast in the system information. [0060] One type of cell access restriction may be “barred cells.” Each UE uses a parameter called “Access Class”, which gives a kind of priority to the UE. The access classes that exist are in the range of 0 to 15. For each of the access classes in the system information, it can be indicated whether a cell is barred or not. A cell can also be barred in general. [0061] Another type of cell access restriction is when a cell is “reserved for operator use”. In the system information, it can be indicated whether a cell is reserved for operator use or not. Depending on whether the UE class is an operator class or not, and whether the UE is in an emergency call or not, the UE can reselect a cell which is reserved for operator use or not. [0062] Moreover, access to the cell may be restricted because it is “reserved for future extension”. In the system information, it can be indicated whether a cell is reserved for future extension or not. [0063] Access to the cell may be restricted due to a PLMN. Each cell belongs to one or several PLMNs. When a UE is powered on, it selects a PLMN and can only change the selected PLMN by specific signaling. When the UE selects/reselects a cell, it checks whether the selected PLMN corresponds to the PLMN of the cell. A UE can use a list of “equivalent PLMNs”, wherein an “equivalent PLMN” is treated as if it was equal to the selected PLMN. A UE that is not trying to do an emergency call can only select/reselect cells that belong to the selected PLMN or an equivalent PLMN of the selected PLMN. [0064] An “intra-frequency cell re-selection indicator” is also sent in the system information to disallow the UE when the cell the UE has selected is barred from reselecting another cell on the same frequency. [0065] Accordingly, the above “cell access restriction” attributes limit the number of candidate cells the UE can consider for cell selection/reselection. Referring to FIG. 6 , a decision process for cell reselection is illustrated. [0066] A major task of the RNC is radio resource management (RRM). Different RRC states, transport channels and physical channels with multiple parameters are available in the UMTS standard to optimize use of available radio resources. [0067] A basic method for RRM purposes is the RRC state transition between CELL_FACH, CELL_DCH, CELL_PCH and URA_PCH states. Combined with these states, when different frequencies are available for communication, the RNC can generally control the number of UEs using a given frequency. However, as described above, in CELL_FACH state, CELL_PCH state and URA_PCH state, the UEs can initiate, based on the measurements and the different rules, the transition from a cell in a given frequency to a cell in another frequency. The transition is either based on normal measurement and cell selection/reselection rules or based on a frequency layer convergence scheme. [0068] When the UE is moved from the CELL_DCH state to another state, the UE selects a cell to camp on or connect to. In general, the UE considers cells on all frequencies, except if the RNC indicates a preferred frequency in an information element (IE) “Frequency Info”. In such a case, the UE preferably selects a cell on the preferred frequency if a suitable cell on the preferred frequency exists. [0069] When the UE is in CELL_FACH state, the RNC may prompt the UE to select a cell on another frequency as the preferred frequency by sending a message including the IE “Frequency Info” to the UE. The UE will then try to select a cell on the preferred frequency. [0070] The 3GPP system can provide multimedia broadcast multicast service (MBMS). The 3GPP TSG SA (Service and System Aspect) defines various network elements and their functions required for supporting MBMS services. A cell broadcast service provided by the prior art is limited to a service in which text type short messages are broadcast to a certain area. The MBMS service, however, is a more advanced service that multicasts multimedia data to terminals (UEs) that have subscribed to the corresponding service in addition to broadcasting multimedia data. [0071] The MBMS service is a downward-dedicated service that provides a streaming or background service to a plurality of terminals by using a common or dedicated downward channel. The MBMS service is divided into a broadcast mode and a multicast mode. The MBMS broadcast mode facilitates transmitting multimedia data to every user located in a broadcast area, whereas the MBMS multicast mode facilitates transmitting multimedia data to a specific user group located in a multicast area. The broadcast area signifies a broadcast service available area and the multicast area signifies a multicast service available area. [0072] FIG. 7 illustrates a process of providing a particular MBMS service, by using the multicast mode. The procedure can be split into two types of actions, those that are transparent and those that are not transparent to the UTRAN. [0073] The transparent actions are described in the following. A user desiring to receive the MBMS service, first needs to subscribe in order to be allowed to receive MBMS services, to receive information on MBMS services, and to join a certain set of MBMS services. A service announcement provides the terminal with a list of services to be provided and other related information. The user can then join these services. By joining, the user indicates that the user wants to receive information linked to services that the user has subscribed to and becomes part of a multicast service group. When a user is no longer interested in a given MBMS service, the user leaves the service, i.e., the user is no longer part of the multicast service group. These actions can be taken by using any means of communication, i.e., the actions may be done using SMS (Short Messaging Service), or by Internet access. These actions do not have to necessarily be done using the UMTS system. [0074] In order to receive a service for which the user is in a multicast group the following actions that are not transparent to the UTRAN are executed. The SGSN informs the RNC about a session start. Then the RNC notifies the UEs of the multicast group that a given service has started in order to initiate reception of the given service. After having broadcast the necessary UE actions and eventually the configuration of the PtM bearers for the given service the transmission of the data starts. When the session stops, the SGSN indicates the stopped session to the RNC. The RNC in turn initiates a session stop. The transmission of the service from the SGSN means for the RNC to provide a bearer service for conveying the data of the MBMS service. [0075] After the notification procedure, other procedures can be initiated between the UE and the RNC and the SGSN to enable data transmission, such as RRC connection establishment, connection establishment towards the PS domain, frequency layer convergence, and counting. [0076] Reception of an MBMS service may be performed in parallel to the reception of other services, such as a voice or video call on the CS domain, SMS transfer on the CS or PS domain, data transfer on the PS domain, or any signaling related to the UTRAN or PS or CS domain. [0077] Contrary to the multicast service, for broadcast services, as shown in FIG. 8 , only the announcement of the service must be done in a transparent manner. No subscription or joining is needed. Afterwards, the actions that are transparent to the RNC are the same as for multicast services. [0078] Referring to FIG. 9 , a typical session sequence from a UTRAN perspective is illustrated. As shown, the SGSN informs the RNC about a session start (step 1 ). The RNC may then perform a counting procedure, which triggers some UEs to establish a connection to the PS domain (step 2 ). Consequently, the establishment of an RRC connection for the UEs is initiated. This allows the RNC to estimate the number of UEs in a given cell that are interested in the service. When the UE has established the PS connection, the SGSN initiates the Iu linking procedure, which provides the list of multicast services the UE has joined to the RNC. [0079] For UEs that have an RRC connection established, and which are interested in the given MBMS service but are not connected to the PS domain, the RNC sends a specific message to the UEs triggering them to establish a PS connection (step 3 ). When the UE has established the PS connection, the SGSN initiates the Iu linking procedure, which provides the list of multicast services the UE has joined to the RNC. For UEs that are not in a CELL_DCH state, a frequency layer convergence scheme allows the RNC to trigger the UEs to change the frequency to which they listen (step 4 ). [0080] Depending on the Radio Resource Management (RRM) scheme, the RNC establishes point-to-multipoint (PtM) or point-to-point (PtP) radio bearers for delivering the MBMS service (step 5 a or 5 b ). The RNC delivers data received from the SGSN to the UEs that are part of the multicast group. After the transmission of the data, the SGSN informs the RNC about the end of the sessions (step 6 ). The RNC then releases the PtP or PtM radio bearers used for transmitting the MBMS data (step 7 a or 7 b ). [0081] Generally, for UEs in an RRC connected state, two possibilities exist. The UE will either have a connection established with the PS domain (PMM connected) or the UE will have no connection established with the PS domain (PMM idle mode). When there is no connection established with the PS domain, the UE will normally have a connection with the CS domain. Otherwise, the UE is not in an RRC connected mode. [0082] For MBMS, two additional control channels are introduced. They are the MCCH and the MICH (MBMS Notification Indicator Channel). As explained above, the MCCH is mapped on the FACH. The MICH is a new physical channel and is used to notify users to read the MCCH channel. The MICH is designed to allow the UEs to perform a DRX (Discontinuous Reception) scheme. DRX allows the reduction of battery consumption for UEs while allowing the UEs to still be aware of any service for which a session is starting. The MICH may be used to inform the UE of a change in a frequency convergence scheme, change of a configuration of a point-to-multipoint (PtM) bearer, switch between the PtM bearer and a point-to-point (PtP) bearer, etc., which all require the MCCH to be read. [0083] The MCCH channel periodically transmits information regarding active services, MTCH configuration, frequency convergence, etc. The UE reads the MCCH information to receive the subscribed services based on different triggers. For example, the UE may be triggered after cell selection/reselection, when the UE is notified of a given service on the MICH, or when the UE is notified via the DCCH channel. The configuration of the MCCH channel is broadcast in the system information. The MICH configuration (i.e. spreading code, scrambling code, spreading factor and other information) is either fixed in the standard, or given in the system information. [0084] The UMTS standard allows use of different frequency bands for data transmission. A frequency band in UMTS is in general specified by a UARFCN (UTRA Absolute Radio Frequency Channel Number), which defines the frequency band used. A given PLMN can use different frequencies. [0085] When a network uses different frequencies, the UEs in a given area select one of the frequencies based on the quality measured on the frequency. The UEs may also select the frequency based on other parameters given in the system information as explained above. To balance the load carried by the different frequencies, the UEs are distributed among the different frequencies. If a given MBMS service is then transmitted on a PtM radio bearer to reach UEs in all frequencies, the transmission must be done in all frequencies. [0086] To increase efficiency, it is advantageous to transmit data on one frequency only and have all UEs interested in a given service reselect a cell in that frequency. Accordingly, this functionality is called “frequency convergence”. The frequency layer to which the UEs should reselect is called a PFL (Preferred Frequency Layer). As shown in FIG. 9 , a typical MBMS session contains a period of “frequency convergence” (step 4 ). [0087] When the frequency convergence process is used for a given service, information regarding the preferred frequency for each service is transmitted in messages either on the MCCH or the system information. To trigger the reselection to the other frequency, different possibilities exist. One possibility is to force the UE to select a cell on the preferred frequency and to forbid all cells on other frequencies from participating in cell reselection/cell selection. [0088] Another possibility is to change the requirements for cell reselection. This may be done by adding an offset to the R criteria, S criteria or H criteria in one of the formulas needed to determine whether cell selection should be done. The offset may be added for the cells on the preferred frequency or for all cells on the non-preferred frequencies. Other possibilities can be envisaged for having the UE reselect a preferred frequency. [0089] For the hierarchical cell structure, the UE preferably reselects the cell with the highest priority. If a frequency convergence scheme is used, it is implied that the UE must be allowed to select a cell on the preferred frequency, disregarding the priority of the preferred frequency. Accordingly, use of the frequency convergence scheme may imply that the hierarchical cell structure should no longer be used. [0090] A PRACH channel is an uplink channel shared amongst different UEs. When a UE wants to send data in the uplink on a PRACH channel, a special mechanism exists to avoid having different UEs transmit at the same time. This mechanism is called “collision avoidance,” and is implemented in the UMTS system based on a slotted Aloha system. The transmission of a message on the PRACH channel is described in FIG. 10 . [0091] Before transmitting on the PRACH channel, the UE transmits a preamble to the NodeB. The preamble comprises a code (signature) the UE chooses randomly amongst the available signatures and transmits it on a special physical channel called a RACH sub-channel. The UE repeats this transmission several times until it receives a positive or negative acknowledgement indicator or a given number of retransmissions are exceeded. The NodeB listens to all sub-channels and tries to detect the given signatures transmitted by the UEs wanting to access the channel. When the NodeB has received the signature, it acknowledges the reception on a special physical channel (AICH) by transmitting a code for indicating to the UE whether the UE is granted access to the PRACH channel or not. Accordingly, the simultaneous transmission of several UEs on the PRACH channel is avoided. [0092] When a UE receives a Not Acknowledged message (NACK) or when the UE does not receive any Acknowledged message (ACK) or NACK on the AICH channel, the UE determines whether it is allowed to restart the collision avoidance process. If another collision avoidance process is allowed according to a fixed algorithm, the UE determines the time to wait before the next collision avoidance process is started. When the UE receives the ACK after a collision avoidance process, i.e. when the UE is granted access to the PRACH, the UE transmits a block set on the PRACH channel. [0093] As described above, a frequency convergence scheme optimizes the use of radio resources by concentrating all UEs interested in a given service onto a given frequency. As a result, some UEs may select a cell on a preferred frequency because they are subscribed to a given MBMS service even though the UEs would not select a cell on the preferred frequency if they were not joined to the MBMS service. [0094] A UE selecting a cell on the “preferred frequency” of an MBMS service to receive the MBMS service potentially has a worse quality of service. This is because potentially many UEs will select the cell or cells on the preferred frequency to receive a given MBMS service on the preferred frequency. Consequently, the load of the cell or cells on the frequency is increased. Also, the radio quality of the selected cell on the preferred frequency may be worse than the radio quality of another frequency. [0095] When a UE wants to establish a call or transmit data in the uplink, depending on the state/mode the UE is in, the UE needs to perform different actions according to the current standard, as shown in Table 1. [0000] TABLE 1 Transmission of Data New Call (C- or U- plane) Idle mode Transmit the “RRC Transmit the “RRC Connection Request” Connection Request” message on RACH message on RACH channel channel Connected Transmit the “Cell Transmit the “Cell Update” mode/ Update” message on message on RACH channel CELL_PCH RACH channel Connected Transmit the “Cell Transmit the “Cell Update” mode/ Update” message on message on RACH channel URA_PCH RACH channel Connected Transmit the “Initial Direct Transmit the data/transmit mode/ Transfer” message on the the “measurement report” CELL_FACH RACH channel message on RACH channel Connected Transmit the “Initial Direct Transmit the data on the mode/ Transfer” message on the dedicated transport channel CELL_DCH dedicated transport channel [0096] As described above, a UE using a frequency convergence scheme because it is joined to an MBMS service will potentially have problems transmitting data on the PRACH channel because of an overloaded cell or bad radio quality. Therefore, a special mechanism is needed to overcome these problems. [0097] The frequency convergence mechanism may also conflict with information on preferred frequencies sent by the RNC at transition from CELL_DCH to CELL_FACH or when the RNC indicates to a UE in a CELL_FACH state to reselect a cell in a given frequency. Accordingly, the efficiency of the system is potentially reduced because active UEs cannot be kept on a separate frequency. SUMMARY OF THE INVENTION [0098] The present invention is directed to interrupting use of a frequency layer convergence scheme that favors selection of a cell on a preferred frequency layer of a joined point-to-multipoint service. [0099] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [0100] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention is embodied in a method for selecting a cell by a mobile terminal in a wireless communication system, the method comprising joining a point-to-multipoint service having a preferred frequency, using a frequency layer convergence scheme for selecting the cell, wherein the frequency layer convergence scheme favors the selection of the cell on the preferred frequency, and interrupting the use of the frequency layer convergence scheme upon an occurrence of a trigger. Preferably, the point-to-multipoint service is an MBMS service. [0101] In one aspect of the invention, the trigger for interrupting the use of the frequency layer convergence scheme is based on a procedure initiated with a network that fails while using the frequency layer convergence scheme. Preferably, the procedure with the network comprises establishing a connection with a core network (CN) domain. The CN domain is at least one of a packet switched (PS) domain and a circuit switched (CS) domain. [0102] In another aspect of the invention, the procedure with the network comprises at least one of a PRACH access procedure, a radio resource control (RRC) procedure for transmitting information to the network, a medium access control (MAC) procedure for transmitting data to the network, and a procedure for selecting a cell on a given frequency according to an order received from the network. [0103] In a further aspect of the invention, the trigger for interrupting the use of the frequency layer convergence scheme comprises receiving a message for initiating a reconfiguration procedure. Alternatively, the trigger for interrupting the use of the frequency layer convergence scheme comprises initiating a procedure selecting a cell on a given frequency according to an order received from a network. [0104] Preferably, interrupting the use of the frequency layer convergence scheme continues until a timer expires. The timer is started when the frequency layer convergence scheme is first interrupted, a procedure initiated with a network comprising a PRACH access procedure fails, a procedure initiated with a network comprising a medium access control (MAC) procedure for transmitting data to the network fails, or a procedure initiated with a network comprising a procedure for selecting a cell on a given frequency according to an order received from the network fails. [0105] A value for duration of the timer is received in a system information message from a network. Alternatively, a value for duration of the timer is a fixed value. [0106] Preferably, the method further comprises selecting a cell on a frequency other than the preferred frequency. Moreover, the method further comprises initiating a procedure with a network and continuing to interrupt the use of the frequency layer convergence scheme until the procedure initiated with the network ends. Also, the method further comprises initiating a procedure with a network, and releasing a connection with a core network (CN) domain when the procedure initiated with the network ends. [0107] In another embodiment of the present invention, a mobile terminal for selecting a cell in a wireless communication system comprises means for joining a point-to-multipoint service having a preferred frequency, means for using a frequency layer convergence scheme for selecting the cell, wherein the frequency layer convergence scheme favors the selection of the cell on the preferred frequency, and means for interrupting the use of the frequency layer convergence scheme upon an occurrence of a trigger. Preferably, the point-to-multipoint service is an MBMS service. [0108] In one aspect of the invention, the trigger for interrupting the use of the frequency layer convergence scheme is based on a procedure initiated with a network that fails while using the frequency layer convergence scheme. Preferably, the procedure with the network comprises establishing a connection with a core network (CN) domain. The CN domain is at least one of a packet switched (PS) domain and a circuit switched (CS) domain. [0109] In another aspect of the invention, the procedure with the network comprises at least one of a PRACH access procedure, a radio resource control (RRC) procedure for transmitting information to the network, a medium access control (MAC) procedure for transmitting data to the network, and a procedure for selecting a cell on a given frequency according to an order received from the network. [0110] In a further aspect of the invention, the trigger for interrupting the use of the frequency layer convergence scheme comprises receiving a message initiating a reconfiguration procedure. Alternatively, the trigger for interrupting the use of the frequency layer convergence scheme comprises initiating a procedure for selecting a cell on a given frequency according to an order received from a network. [0111] Preferably, interrupting the use of the frequency layer convergence scheme continues until a timer expires. The timer is started when the frequency layer convergence scheme is first interrupted, a procedure initiated with a network comprising a PRACH access procedure fails, a procedure initiated with a network comprising a medium access control (MAC) procedure for transmitting data to the network fails, or a procedure initiated with a network comprising a procedure for selecting a cell on a given frequency according to an order received from the network fails. [0112] A value for duration of the timer is received in a system information message from a network. Alternatively, a value for duration of the timer is a fixed value. [0113] Preferably, the mobile terminal further comprises means for selecting a cell on a frequency other than the preferred frequency. Moreover, the mobile terminal further comprises means for initiating a procedure with a network and means for continuing to interrupt the use of the frequency layer convergence scheme until the procedure initiated with the network ends. Also, the mobile terminal further comprises means for initiating a procedure with a network and means for releasing a connection with a core network (CN) domain when the procedure initiated with the network ends. [0114] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0115] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects in accordance with one or more embodiments. [0116] FIG. 1 is a block diagram of a general UMTS network architecture. [0117] FIG. 2 is a block diagram of a structure of a radio interface protocol between a terminal and a network based on 3GPP radio access network standards. [0118] FIG. 3 illustrates the mapping of logical channels onto transport channels in the mobile terminal. [0119] FIG. 4 illustrates the mapping of logical channels onto transport channels in the network. [0120] FIG. 5 illustrates possible transitions between modes and states in the UMTS network. [0121] FIG. 6 illustrates a decision process for cell selection. [0122] FIG. 7 illustrates a process of providing a particular point-to-multipoint service using a multicast mode. [0123] FIG. 8 illustrates a process of providing broadcast services. [0124] FIG. 9 illustrates a session sequence from a network perspective. [0125] FIG. 10 is flow chart for transmitting a message on a PRACH channel. [0126] FIG. 11 illustrates the interruption of a frequency layer convergence scheme in accordance with one embodiment of the present invention. [0127] FIG. 12 illustrates the interruption of a frequency layer convergence scheme using a timer in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0128] The present invention relates to a UE having joined a service for which a “preferred frequency” is defined but should not use a “frequency layer convergence” scheme under certain circumstances. For example, the frequency layer convergence scheme should not be used when the UE tries to establish a new call, or when the UE fails to access the network on the preferred frequency while using a method favoring a preferred frequency of a joined MBMS service. [0129] Several methods exist for determining whether the UE should stop applying a method favoring the selection of a cell on a given “preferred frequency”. Preferably, when the frequency layer convergence scheme is interrupted for the preferred frequency, it should be interrupted for any service for which the preferred frequency is the given frequency. [0130] In accordance with a first embodiment of the present invention, the UE stops using the frequency layer convergence scheme when certain conditions occur as a result of using the frequency convergence scheme. Preferably, during a PRACH access procedure, when the UE receives in a MAC layer notification that a collision avoidance process has failed in a physical layer, or when the UE receives a NACK on the AICH channel or receives no response at all from a NodeB, or when a MAC procedure for transmitting data on the preferred frequency fails as a result of the UE using the frequency layer convergence scheme, the UE ceases to use the scheme. [0131] In accordance with a second embodiment of the present invention, the UE stops using the frequency layer convergence scheme when the UE must perform a specific procedure, such as when the UE tries to perform an emergency call. Another specific procedure is when the NAS (Non-Access Stratum) layers indicate to the AS (Access Stratum) layer of the UE to establish a connection with a CN domain for a specific reason, such as Originating Conversational Call, Originating Streaming Call, Originating Interactive Call, Originating Background Call, Originating Subscribed Traffic Call, Terminating Conversational Call, Terminating Streaming Call, Terminating Interactive Call, Terminating Background Call, Emergency Call, Inter-RAT cell re-selection, Inter-RAT cell change order, Registration, Detach, Originating High Priority Signaling, Originating Low Priority Signaling, Call Re-establishment, Terminating High Priority Signaling, Terminating Low Priority Signaling, Terminating-cause unknown, or any subset of these reasons. [0132] In accordance with a third embodiment of the present invention, the UE stops using the frequency layer convergence scheme when the UE is asked to select a cell on a given frequency, either in CELL_FACH state, in CELL_PCH state, in URA_PCH state or in idle mode. [0133] When the UE stops using the frequency layer convergence scheme for one of the above reasons, it becomes necessary to also define a method for restarting the frequency layer convergence scheme again. Preferably, a trigger for restarting the frequency layer convergence scheme may be when the procedure that triggered the stoppage of the frequency layer convergence scheme is finished successfully or unsuccessfully. Alternatively, at a point when use of the frequency layer convergence scheme is stopped, the UE may start a timer such T freq — conv — int . At the end of a time period of the timer, use of the frequency layer convergence scheme is restarted. Accordingly, this limits interruption of the use of the frequency layer convergence scheme. Preferably, the timer is broadcast on the system information of the cell. [0134] Referring to FIG. 11 , a method for executing an emergency call by a UE with respect to a frequency layer convergence scheme is illustrated. Initially, the UE in a CELL_FACH, CELL_PCH, URA_PCH or idle mode begins using a frequency layer convergence scheme (step 1 ). This allows the UE to reselect a preferred frequency. Subsequently, when NAS indicates to the AS that a connection to a CN domain must be established, a specific cause value is given to the UE (step 2 ). [0135] Based on the cause value, the UE may stop use of the frequency layer convergence scheme (step 3 ). Accordingly, when the UE stops using the frequency layer convergence scheme, the UE changes the way it evaluates the neighboring cells. When the UE needs to establish a connection to a core network domain when the UE is in an idle mode, CELL_FACH, CELL_PCH or URA_PCH state, it is implied that the UE must transmit a message, such as Cell Update, RRC Connection Request and/or Initial Direct transfer, on the PRACH channel to the NodeB (step 4 ). [0136] When the current cell or cells on the current frequency are loaded, the PRACH channel access may fail on the current frequency (step 5 ). Eventually, the UE will reselect a cell on another frequency as the preferred frequency since the frequency layer convergence scheme is no longer used (step 6 ). After the cell reselection, access to the PRACH will have a higher chance of succeeding because the best cell is chosen (step 7 ). [0137] After the call is finished, the connection to the CN domain is released (step 8 ). The UE will then restart use of the frequency layer convergence scheme if it is still applied (step 9 ). [0138] Referring to FIG. 12 , a method for stopping frequency layer convergence by a UE based on a timer is illustrated. Initially, the UE in a CELL_FACH, CELL_PCH, URA_PCH or idle mode begins using a frequency layer convergence scheme (step 1 ). This allows the UE to reselect a preferred frequency. [0139] Subsequently, any one of a number of events may occur (step 2 ). For example, the NAS may indicate to the AS that a connection to a CN domain must be established and gives a specific cause value to the UE. Or an RRC procedure is started which requires transmission in the uplink. Also, the transmission of data in the uplink may be started. Or the UE may be ordered to select a cell on a given preferred frequency. [0140] Accordingly, the UE ceases use of the frequency layer convergence scheme. When the UE stops using the frequency layer convergence scheme, the UE will change the way it evaluates the neighboring cells. Also, upon stopping the use of the scheme, the UE starts a timer T freq — conv — int (step 3 ). The duration of the timer may be a fixed value, or the UE may utilize a value read in the system information. [0141] The UE then transmits data on the PRACH channel to the NodeB (step 4 ). When the current cell or cells on the current frequency are loaded, the PRACH channel access may fail on the current frequency (step 5 ). [0142] An alternative to starting the timer T freq — conv — int in step 3 is to start it once the first PRACH access procedure has failed (step 6 ). The PRACH access procedure may fail due to a reception of a NACK, no reception of a response message, or when a retry mechanism in the MAC layer has timed out, such that there is no more retransmission. The duration of the timer may be a fixed value, or the UE may utilize a value read in the system information. [0143] Eventually, the UE will reselect a cell on another frequency as the preferred frequency since the method for frequency layer convergence scheme is no longer used (step 7 ). After the cell reselection, access to the PRACH will have a higher chance of success because the best cell is chosen (step 8 ). [0144] When the timer T freq — conv — int expires and after the call has ended, the connection to the CN domain is released (step 9 ). The UE will then restart use of the frequency layer convergence scheme if it is still applied (step 10 ). [0145] Accordingly, the present invention ensures a UE having joined an MBMS service, will have the same or similar chance of success in establishing a new call/emergency call or transmitting data, as the same UE not having joined an MBMS service. [0146] Although the present invention is described in the context of mobile communication, the present invention may also be used in any wireless communication systems using mobile devices, such as PDAs and laptop computers equipped with wireless communication capabilities. Moreover, the use of certain terms to describe the present invention should not limit the scope of the present invention to a certain type of wireless communication system. The present invention is also applicable to other wireless communication systems using different air interfaces and/or physical layers, for example, TDMA, CDMA, FDMA, WCDMA, etc. [0147] The preferred embodiments may be implemented as a method, apparatus or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” as used herein refers to code or logic implemented in hardware logic (e.g., an integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.) or a computer readable medium (e.g., magnetic storage medium (e.g., hard disk drives, floppy disks, tape, etc.), optical storage (CD-ROMs, optical disks, etc.), volatile and non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, firmware, programmable logic, etc.). [0148] Code in the computer readable medium is accessed and executed by a processor. The code in which preferred embodiments are implemented may further be accessible through a transmission media or from a file server over a network. In such cases, the article of manufacture in which the code is implemented may comprise a transmission media, such as a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention, and that the article of manufacture may comprise any information bearing medium known in the art. [0149] The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structure described herein as performing the recited function and not only structural equivalents but also equivalent structures.

The present invention is directed to interrupting use of a frequency layer convergence scheme that favors selection of a cell on a preferred frequency of a joined point-to-multipoint service. Specifically, a mobile terminal that has joined a point-to-multipoint service having a preferred frequency uses a frequency layer convergence scheme for selecting a cell. The frequency layer convergence scheme favors the selection of a cell on the preferred frequency layer. However, use of the frequency layer convergence scheme is interrupted upon an occurrence of a trigger.

The invention is based on a priority application EP 07 301 171.0 which is hereby incorporated by reference. TECHNICAL FIELD The invention relates to a method for providing unequal error protection to data packets in a burst transmission system. Each burst comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets are grouped based upon respective priority levels. The invention also relates to a burst transmission system for performing said method. BACKGROUND OF THE INVENTION An example for such a burst transmission system is the handheld enhancement of the DVB (Digital Video Broadcasting) system. The DVB-H enhancements to the DVB-T (Digital Video Broadcasting Terrestrial) specifications include a forward error correction computed across the data section of a burst. The forward error correction code is placed in the error protection section of the same burst over which data section the error protection code has been computed. An example of such forward error correction is implemented in DVB-H as well as DVB-SH. The DVB-H as well as the DVB-SH (DVB satellite to handheld) both implement the multi-protocol encapsulation. The multi-protocol encapsulation (MPE) encapsulates multiple types of data, especially IP (Internet Protocol) datagrams into the data section of a burst. DVB-H/SH also implements the MPE-FEC (Multi Protocol Encapsulation-Forward Error Correction). MPE-FEC is the link layer error protection of DVB-H and DVB-SH. MPE-FEC provides intra burst data protection. A MPE-FEC frame is a matrix of 255 columns and a variable number of rows, e. g. 256, 512, 768, or 1024. Each element in the matrix of the MPE-FEC frame represents a byte. An MPE-FEC frame is an example of a burst. The first 191 columns of the MPE-FEC contain the IP datagrams that will be transmitted. This portion is the data section of the burst and is also called application data table (ADT). The rest of the 64 columns are dedicated to the forward error correction (FEC) generated by for example an eraser code, such as Reed Solomon, LDPC (Low Density Parity Check Code), etc. The FEC is contained in the error protection section of the burst. The FEC is also called RSDT (Reed Solomon Data Table) or inner-FEC. The inner-FEC is computed over the rows of the metrics ADT. It involves 1 D error correction, which is for example a FEC computed on each row of the ADT metrics. The redundancy created by the inner-FEC protects the loss of one datagram in one burst. Thus, the inner-FEC can insure an intra burst protection. In a wireless network, such as DVB-H, DVB-SH, WiMAX (Worldwide Interoperability for Microwave Access), 3G/LTE (3rd Generation Long Term Evolution), end users have different requirements in terms of latency video visual quality, processing capabilities and power. It is thus a challenge especially for broadcast services to design a delivery mechanism that not only achieves efficiency in network bandwidth but also meets the heterogeneous requirement and capacities of the end users. To address the above challengers the different quality of service requirements in all components of a media delivery system from end to end should be supported simultaneously. Examples of such media delivery systems are voice service, http services etc. Another example of such a media delivery system is a video delivery system which transmits scalable encoded video. Scalable video encoding is an advantageous way to meet the needs to achieve efficiency in network bandwidth and also to meet the heterogeneous requirement and capacities of the end users. In scalable video coding the signal is separated into multiple layers. The layers have different priorities. The base layer is the layer of highest priority. It can be independently decoded and provides basic video quality. The base layer must be robust to be received by users over all the network, what ever the radio conditions or the radio link quality might be. The enhancement layers can only be decoded together with the base layer and further increase the video quality and/or the video basic special and temporal resolution. The base layer in connection with the enhancement layer or enhancement layers provide video with the enhanced quality. Each terminal decodes at least the base layer and a number of enhancement layers that is linked to the capabilities of the terminal. Using scalable video layers allows networks providing multimedia broadcast and multicast services to adapt efficiently to the variability of the radio conditions, e. g. variable carrier to interference ratio or signal to noise ratio. It allows to optimise the usage of the radio resources using modulation and coding schemes leading to higher spectrum efficiency. Terminals experiencing bad radio link quality for example decode only the base layer, e. g. typically users at the edge of a cell for example. The base layer must be enough robust to be received by users all over the network or cell what ever the radio conditions or the radio link quality are. This can be achieved by choosing an adequate modulation and coding scheme. The enhancement layers are decoded only even the radio link quality is good, e. g. typically users near the antenna. The enhancement layer or the enhancement layers are differently protected than the base layer. They are usually less protected than a base layer e. g. by using a less robust modulation and coding scheme but leading to higher radio data rate. In the document “Multi burst sliding encoding (MBSE)” of Luc Ottavj, Antoine Clerget, Amine Ismail, which was presented during a technical working group within the DVB-SSP (DVB satellite service to portable devices) standardization, an outer-FEC algorithm is presented which extends the intra-burst protection to an inter-burst protection, so that complete burst losses may be recovered. In order to achieve this, data coming from several bursts are interleaved before FEC protection is applied. In the US patent application 2006/0262810 A1 a method for providing error protection to data packets in a burst transmission system is described. Error protection is provided unequally with respect to priority levels of the data packets. The error protection provided is inserted within one burst, thus protecting the loss of one data packet in one burst. The unequal error protection provided calculates the error protection code over the data section of one burst and puts the calculated error code in the error protection section of said same burst. The object of the invention is to provide a method for providing unequal error protection to data packets in a burst transmission system with extended protection. Another object of the invention is to provide a burst transmission system with unequal error protection for data packets with extended protection. SUMMARY OF THE INVENTION These objects and other objects are solved by the features of the independent claims. Features of preferred embodiments of the invention are found in the dependent claims. The invention provides a method for providing unequal error protection to data packets in a burst transmission system e. g. DVB-H or DVB-SH system. Each burst comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets to be transmitted are grouped based upon respective priority levels, e. g. different layers of e. g. coded video data or other layered coded media data. The error protection provided to each group of data packets is based upon the respective priority level of the data packets. The error protection is provided by error protection codes contained in the error protection section of the bursts. The error protection codes for each group of data packets are created using data of data packets of said group which are contained in the data section of two or more bursts forming a first set of bursts. This means that error codes are computed using data of data packets belonging to the group of data packets which are contained in two or more bursts. The created error protection codes are then transmitted in the error protection section of one or more bursts forming a second set of bursts. The present invention extends the error protection over more than one burst. This enables recovery of consecutive bursts loss. It is adapted to media having long interruptions or fade outs, e. g. by a number of obstacles that may be responsible for a complete interruption of the signal of several seconds with the direct satellite link to a mobile phone. According to a preferred embodiment of the invention the first set of bursts is disjoint from the second set of bursts. This ensures that the data from which the error codes are computed is contained in completely different bursts from the bursts in which the error codes are contained. The second set of bursts may follow immediately the first set of bursts in this embodiment. This enables rapid recovery of bursts when there has been a fade out in the transmission connection. According to another preferred embodiment of the invention the first set of bursts has a non-empty intersection with the second set of bursts, i. e. the first set of bursts overlaps with the second set of bursts. This means that the error codes generated over the data sections of the first set of bursts are contained in the error protection section of bursts which are possibly also part of the first set of bursts. This ensures a faster recovery possibility after a fate out in the transmission connection. The unequal error protection is preferably achieved by using different numbers of bursts contained in the first set of bursts for different groups of data packets. Data packets within one group belong to the same priority level. For different priority levels the error protection codes are generated over a different number of bursts. This allows to balance the required security level of protection and the generated redundancy according to different priorities. According to a preferred embodiment of the invention the second set of bursts used for transmitting the error protection codes for a group of data packets of a higher priority contains a higher number of bursts in the second set of bursts used for transmitting the error protection codes for a group of data packets of lower priority. This allows to spread the error protection codes over more bursts for higher priority data packets. This allows for balancing required error protection and overhead. According to a preferred embodiment of the invention the groups of data packets correspond to layers of layered encoded data, e. g. layered encoded video data. Layered encoded video data is also known as scalable video. Scalable video can be seen as multiple, e. g. two or more hierarchical additive layers. This can be for example a basic layer providing a basic video quality and one or more enhancement layers providing finer quality improvements. The basic layer then corresponds to the highest priority layer. Packets of the basic layer of the video data are packets with the highest priority level. The data packets of the enhancement layers are of lower priority. The invention also concerns a burst transmission system, in particular a wireless burst transmission system such as a DVB-H or DVB-SH system. Each burst within said burst transmission system comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets are grouped based upon respective priority levels and unequal error protection is provided to each group of data packets based upon the respective priority level. The error protection is provided by said error protection codes contained in the error protection section of the bursts. The burst transmission system comprises means for creating the error protecting codes for each group of data packets using data of data packets of said group which are contained in the data section of two or more bursts performing a first set of bursts. The burst transmission system further comprises means for transmitting the created error protection codes in the error protection section of one or more bursts performing a second set of bursts. This allows for an error protection extending beyond one burst. According to a preferred embodiment of the burst transmission system the unequal error protection is provided to groups of data packets which correspond to layers of layered encoded video data. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will become apparent in the following detailed description of preferred embodiments of the invention illustrated by the accompanying drawings given by way of non-limiting illustrations. FIG. 1 shows a schematic overview over one burst, FIG. 2 shows a schematic overview over a first set of bursts and a second set of bursts, FIG. 3 shows an overview over a first set of bursts and a second set of bursts, FIG. 4 shows an example of parameterization for error protection parameters, and FIGS. 5-7 show examples of unequal error protection. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a schematic overview of a burst 10 comprising a data section 20 and an error protection section 30 . Comprised in the error protection section 30 are error protection codes for protecting intra burst loss and protection codes for protecting against losses extending over more than one burst. Intra burst error protection is for example done by MPE-FEC in the case of DVB-H or DVB-SH. In the case of layered video transmission, the layers of unequal importance of a scalable video scheme should advantageously lead to an unequal error protection policy within the network. The unequal error protection according to the invention is provided by applying the extra burst error protection as shown for example in FIG. 2 according to priority levels of groups of data packets. FIG. 2 shows an example of extra burst error protection for a group of data packets. Extra burst error protection extends the error protection beyond the borders of one single burst. Shown in FIG. 2 are bursts 10 each comprising a data section 20 and an error protection section 30 . Error protection for data packets belonging to a group of data packets of the same priority level is provided by calculating error protection codes using data of data packets of bursts contained in a first set of bursts 50 . The calculated error protection codes are transmitted in the error protection section 30 of bursts 10 belonging to a second set of bursts 60 . In the example shown in FIG. 2 the first set of bursts 50 is disjoint from the second set of bursts 60 . A second set of bursts 60 follows the first set of bursts 50 in time. The error protection sections 30 of the bursts 10 also contain error protection codes for protecting intra burst losses. These error protection codes for protecting against intra burst losses are calculated over data contained in the data section 20 of the same burst 10 . FIG. 3 shows an example of extra burst error protection where the first set of bursts 55 has a non-empty intersection with the second set of bursts 65 . The example shown in FIG. 3 also provides error protection for a group of data packets belonging to the same priority level. As for the example of FIG. 2 unequal error protection for groups of data packets of different priority levels can be provided by varying the number of bursts contained in the first set of bursts 50 , 55 and the second set of bursts 60 , 65 . In the example shown in FIG. 3 extra burst error protection is provided by calculating error protection codes over data contained in the bursts 10 of a first set of bursts 55 . Those calculated error codes are transmitted in the error protection section 30 of a group of bursts 10 of a second set of bursts 65 . The first set of bursts 55 overlaps with a second set of bursts 65 . The quality degradation in a video transmission over radio compared to a perfect transmission is mainly determined by the packet lost behaviour observed at the video decoder. The propagation channel presents many impairments, e. g. deep fading, shadowing, etc., leading to a bursty packet loss. If one packet is lost it is very likely that consecutive packets will also be lost. In order to offer the video service to all the terminals in the cellular broadcast network, the base layer of video must be protected more than the enhancement layers, as the enhancement layers have less importance to the video decoding. The base layer can therefore be protected more by calculating more redundancy in the inner forward error correction codes. Inner forward error correction means that intra burst loss of a packet is protected by the error codes in the error correction section of said same burst. In the case of shadowing or deep fading for example a whole burst can be lost so. This would mean that the video service would be interrupted. The presented inventive method resolves this problem by the extra burst forward error correction. The extra burst error correction can be advantageously coupled to the inner burst error correction. The intra burst error correction is computed on the number N of the rows of a burst. The intra burst error correction is characterised by its rate equalling M/(M+K). In this equation M denotes the number of columns in the data section of the burst K denotes the number of columns in the error protection section of the burst. The extra burst error correction computed from the columns of successive bursts leads to a rate equalling C/(C+S). The parameter C gives the number of successive bursts, C contained in the first set of bursts 50 or 55 . The parameter S gives the number of bursts on which the extra burst error correction codes are spread. S is the number of bursts contained in the second set of bursts 60 or 65 . In global this gives the coding rate of inner protection coding rate plus extra burst protection coding rate. The global coding rate is the sum of the intra burst protection coding rate plus the extra burst protection coding rate. The parameters K, C, and S must be well chosen to keep the global protection coding rate at an acceptable level. The invention focuses on varying the rate of coding of the extra burst error protection to ensure a high protection for the base layer and to keep a good bandwidth efficiency. Thus K is kept fixed for the following examples. Of course K can be varied in order to further increase the protection for the base layer. The variation of K can be advantageously combined with the variation of C and S. The rate of extra burst error protection can be denoted by α. α is then given by C/(C+S). This can be transformed to S=(1/α−1)C. In FIG. 4 are shown three lines of possible parameter choices. Assuming that there is one base layer the extra burst error protection coding rate is given by α B . Assuming that there are two enhancements layers E 2 and E 1 the extra burst error protection coding rates are given by α E2 and α E1 . The lines with the corresponding angle α B , α E1 or α E2 give the parameter choices sets for possible parameter combinations of S and C for the respective layers. In FIG. 4 the different curve of variations of S depending on the value of C are plotted. There is an infinity of solutions to fix the values of C and S. The choice of the values for C and S will advantageously be done by the operator of the telecommunication network or the operator of the service provider, e. g. the video service provider. In general the protection is higher when the parameter α is lower. This is the reason why the parameter α B shown in FIG. 4 is larger than the parameter α E1 for the first enhancement layer and larger than the parameter α E2 for the second enhancement layer E 2 as shown in FIG. 4 . In FIGS. 5 , 6 , and 7 examples of three extra burst protection schemes are given. For a given C (C fixed) increasing S leads to a lower α. A lower α leads to a higher protection. Allowed value of S allows thus to obtain more redundancy. The first example of a scheme shown in FIG. 3 therefore spreads the error protection codes generated from the basic flow B over a higher burst number S then the protection codes generated from the enhancement flow E. C is kept constant. In this case the protection inequality lays in the redundancy quantity. It is shown in FIG. 5 that for the basic layer B the first set of bursts 50 .B comprises four bursts. The first set of bursts for the enhancement layer E 50 .E comprises also four bursts. The parameter C is thus kept constant. The second set of bursts for the base layer 60 .B contains two bursts. The second set of bursts 60 .E for the enhancement layer contains only one burst. Redundancy is thus increased by using a higher number of bursts for the second set of bursts 60 .B for the base layer than for the second set of bursts 60 .E for the enhancement layer. For the example given in FIG. 6 the parameter S is kept fixed. Increasing C thus leads to a higher value of α. The extra burst error protection protects less in this case. Indeed, the ratio of the redundancy quantity to the data quantity decreases which leads to the diminution of the correction capacity of the error correction. Thus, the example given in FIG. 6 uses a lower number of successive bursts C for generating the error correction code in the basic flow case than in the enhancement flow case. The number of bursts contained in the second set of bursts 60 .B and 60 .E is equal to 2 for both basic layer and the enhancement layer in FIG. 6 . The parameter S is thus equal to 2 for the example given in FIG. 6 . The number of bursts contained in the first set of bursts 50 .B for the basic layer is 2 for the example given in FIG. 6 . The number of bursts contained in the first set of bursts 50 .E for the enhancement layer is equal to 4 for the example given in FIG. 6 . However, in the scheme given in FIG. 6 the protection against the lost burst recovery of the base layer is dramatically reduced. Indeed, the lower the value for the parameter C, which is the number of bursts contained in the first set of bursts, the number of bursts recovered when lost is reduced. For this reason the value for the parameter C should be increased to enable a terminal to receive the base layer even in a presence of large shadowing and deep fading, as is the case for example when the terminal is located under a bridge. In order to keep some correction capacity for large C values S must be increased as well. This leads to a third example of extra burst error correction as shown in FIG. 7 . The example shown in FIG. 7 uses a higher number of successive bursts C for generating the error correction code on the base flow than in the enhancement flow case. As shown in FIG. 7 the first set of bursts 50 .B for the base layer comprises 4 bursts. The first set of bursts 50 .E for the enhancement layer comprises 3 bursts. The value for S is different for both flow types as well. It is adapted to the values for the parameters C in order to keep a good correction capacity for the base layer B. The value for S is 1 for the second set of bursts 60 .E for the enhancement layer. The number of bursts contained in the second set of bursts for the basic layer 60 .B is 2. All the examples given above lead to an unequal error protection for different priority groups of media data, e. g. different layers of video and data providing an extra burst error correction.

The present invention relates to a method for providing an equal error protection to data packets in a burst transmission system. The data packets are grouped based upon respective priority levels and error protection is provided to each group of data packets based upon the respective priority level. The error protection codes for each group of data packets depending on the respective priority level is created using data of data packets of the group which are contained in the data section ( 20 ) of two or more bursts ( 10 ) forming a first set of bursts ( 50, 50 .B, 50 .E, 55 ) and the created error protection codes are transmitted in the error protection section ( 30 ) of one or more bursts ( 10 ) forming a second set of bursts ( 60, 60 .B, 60 .E, 65 ). The invention further relates to a burst transmission system for performing said method.

BACKGROUND OF THE INVENTION This invention relates to a method of manufacturing reinforced insulating panels, and particularly to a method of making reinforced insulating panels impregnated with thermosetting resin, which utilize glass fiber reinforced material provided in a three-dimensional construction, wherein the delamination between surface material and insulating material is minimized and wherein the mechanical durability thereof is great. A conventional reinforced panel of aluminum-insulating material is shown in FIG. 1, and is used as carrying boxes on refrigerator vehicles or containers and comprise an insulating member 101 and aluminum panels 102 fixed to both faces of the insulating member 101. Containers for marine transportation made of such panels are likely to corrode at their surface materials due to seawater and sea wind. When applying such panels to refrigerator containers or carrying boxes of refrigerator vehicles, such containers and boxes suffer from vertically acting compression and severe buckling load. When joining surface member and insulating member, e.g., urethane foam of simple laminated structure, insulating members are likely to isolate or break at the interfaces thereof, resulting in the loss of refrigerating and freezing-retaining properties, which shortens the lives of carrying boxes or refrigerator containers. SUMMARY OF THE INVENTION An object of this invention is to provide a reinforced insulating panel which has great mechanical endurance properties and remarkably represses or prevents the delamination between surface members and insulating members. Another object of this invention is to provide a method of making a reinforced insulating panel which is of three-dimensional construction comprising insulating members and glass fiber textiles impregnated with thermosetting resin. The reinforced insulating panel according to this invention is made by covering inner covering of glass fiber textiles with urethane foam of regular size, quilting the inner covering and urethane together, covering the quilted member with an outer covering of glass fiber textiles, and impregnating the outer-covered member with thermosetting resin and hardening the impregnated member. Still another object of this invention is to provide a method of making a reinforced insulating panel comprising the steps of equalizing the length of urethane foam of regular size and glass fiber textiles, quilting the same-length members together so as to constitute reinforced members, providing partitioning members between the reinforced members, covering the surface of the reinforced members, and partitioning members with glass fiber textiles, impregnating the surface-covered member with thermosetting resin and hardening the impregnated member. As partitioning members, partitioning panels of FRP are inserted. Alternatively, a single inner covering of glass fiber textiles longer than the insulating member is provided for covering the insulating member in the c-shape. The insulating member and single inner covering are quilted together for having vertical parts of the inner covering serving as partitioning members between the reinforced members. Alternatively, upper and lower inner coverings of glass fiber textiles are provided, the edges of each inner covering being longer than the thickness of the insulating member by half. The margin parts of the edges are bent and fixed to the end faces of the insulating members thereby forming partitioning members. The reinforced insulating panels of I-beam construction of this invention are obtained by any one of the above-described methods. BRIEF DESCRIPTION OF THE DRAWINGS Further features and details of the invention will be apparent from the following description of the embodiments which are given with reference to the accompanying drawings, in which: FIG. 1 is a sectional view of the conventional aluminum insulating panel; FIG. 2 is a perspective view of one embodiment of first molded goods of reinforced insulating panel of the present invention; FIG. 3 is a plan view of FIG. 2; FIG. 4 is a sectional view of a finished reinforced insulating panel; FIG. 5A is a perspective view of a middle member of one embodiment of this invention; FIG. 5B is a perspective view of a middle member of another embodiment of this invention; and FIGS. 6A, 6B and 6C illustrate the reinforced insulating panels of the present invention having several kinds of partitioning members. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIGS. 2 to 4, an inner covering of glass fiber textiles 2 covers both sides of an insulating panel 1 of urethane foam, or the like. The insulating panel 1 of regular shape and inner covering of glass fiber textiles 2 are quilted together by reinforcing fiber thread 3. The inner covering of glass fiber textiles 2, insulating panel 1 and reinforcing fiber thread 3 constitute a middle member (a). The middle member (a) has a three-dimensional construction. The material of the inner covering of glass fiber textiles 2 is roving fiber. The reinforcing fiber thread is made by glass fiber, carbon fiber or aramid fiber. The thickness and density of the reinforcing fiber thread 3 depends on the use of insulating panel 1. Each inner covering of glass fiber textiles 2 of the middle member (a) is enclosed by an outer covering of glass fiber 4 and then impregnated with thermosetting resin for fire retardancy. Thereby, reinforcing fiber thread 3, which has been exposed outside of the inner covering of glass fiber textiles 2 and thus has been in an unstable state, is in fixed position. The inner and outer coverings are made of one-direction or plain cloth. The thermosetting resin is unsaturated polyester resin, epoxy resin or melamine resin and is thereby fire retardant. The condition of hardening depends on the kind of resins and the use of the insulating panel. Thermosetting resin is used in the shape of prepeg which is made by pre-saturation of outer glass fiber 4. Otherwise, the thermosetting resin is produced by pouring liquid thermosetting resin into the reinforcing material and hardening the reinforcing material. The resin saturating process influences the durability and mechanical strength of the finished insulating panel. Therefore, during the process, molding should be achieved as close as possible so as not to produce pores. As shown in FIG. 6A, the middle members (a) obtained are arranged in a line. FRP partitioning members 5 are inserted between the middle members (a). An outer covering of glass fiber 4 encloses the middle member (a) and the partitioning member 5. Then, the enclosed middle member (a) is impregnated in the fire retardant thermosetting resin and hardened, thus producing the reinforcing material. As described above, when using FRP partitioning members 5 as the partitioning member, the I-beam construction formed when molding FRP causes an increase in compressive load with respect to the horizontal direction of the panel face. Furthermore, when an external force acts in the vertical direction, the bending strength increases, causing deformation of the insulating reinforcing panel to decrease remarkably. As shown in FIG. 5A, an inner covering of glass fiber textiles 2 is larger than an insulating panel 1 of urethane foam, or the like, and encloses the insulating panel 1 in the U-shape. That is, the inner covering of glass fiber textiles is longer than one face of the insulating panel 1. A reinforcing fiber thread 3 quilts the insulating panel 1 and the inner face of glass fiber textiles 2, thus forming integral margin members 2a. The integral margin members 2a serve as partitioning members. The members 1, 2, 3 and 2a constitute a middle member (a'). As shown in FIG. 6B, the middle members (a') are arranged in a line as follows. The back of one of the middle members (a') contacts an open face of the other middle member (a'). Outer coverings of glass fiber 4 enclose the upper and lower faces of the middle members (a'). Then, the enclosed middle members (a') are impregnated with thermosetting resin and hardened, thereby producing a deformed reinforcing material. As shown in FIG. 5B, upper and lower inner coverings of glass fiber textiles 2 are larger than the insulating panel 1 of urethane foam, or the like (2) and enclose the insulating panel 1 in the shape of U and inversed U. That is, the upper and lower glass fiber inner covering of glass 2 enclose approximately half of the one face of the insulating panel 1. The insulating panel 1 and the upper and lower coverings of glass fiber textiles 2 are quilted together by reinforcing fiber thread 3. Separable margin parts 2b serve as the partitioning member. The members 2b, 1, 2 and 3 constitute middle members (a"). As shown in FIG. 6c, the middle members (a") are arranged in a line and are enclosed by outer coverings of glass fiber 4. The enclosed middle members (a") are impregnated with fire retardant thermosetting resin and hardened. Thus, a deformed reinforcing material in accordance with a second embodiment is obtained. Regardless of what methods are chosen, glass fiber textiles and reinforcing textile thread which have passed the hardening process serve as an excellent FRP. Furthermore, resin may be impregnated into the glass fiber textiles by capillary action and hardened. Therefore, each strand of fiber becomes a kind of FRP bar. According to a bending test, when thickness of the covering was about 1.5-2.0 t when using textiles having the same property as leather, the strength was more than two times that of insulating panels having no partitioning members and the deformation decreases by less than 1/2 when compared with insulating panels having no partitioning members. The insulation-reinforcing panels of this invention are reinforced in a three-dimensional way and have a unitary construction. Therefore, the insulation-reinforcing panels of this invention sufficiently endure continuous compression and withstand buckling. Furthermore, the insulation-reinforcing panels of this invention generally are capable of absorbing shock. Therefore, the panels have excellent anti-shock properties. The conventional aluminum/urethane foam containers, when used for sealift, are susceptible to corrosion by seawater. However, when applying the insulation-reinforcing panel of three-dimensional construction to containers, or the like, such containers are not likely to corrode as a result of seawater and their mechanical life increases. Furthermore, the weight of such containers decreases by 20%. In addition, the reinforced insulation panel of this invention is reinforced by reinforcing material, e.g., glass fiber textiles, therefore, even if the reinforced insulating panel is cracked, the cracks do not spread. Therefore, the reinforced insulating panel of this invention has a much longer life than conventional insulating panels. FRP molding materials are easier to manufacture than general metal materials. The FRP molding materials are attached to metal panels with rivets, or the like. However, since the reinforced insulating panels are simultaneously impregnated with thermosetting resin, the joining strength is great, thus preventing delamination. Furthermore, the panels have a fluid blocking function wherein fluid cannot penetrate the inside of the panel. In addition, by providing partitioning members between the middle members, the compressive load in the horizontal direction of the panel face increases and the bending strength with respect to the external force acting in the vertical direction also increases. Therefore, the reinforced insulating panel is prevented from deforming. While the invention has been described in connection with the preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modification, within the scope of the appended claims.

A method of making a reinforced insulating panel which includes the steps of covering insulating material, such as urethane foam of a regular size with glass fiber textiles, quilting the insulating material and the glass fiber textiles together so as to produce an integral middle member, covering the inner covering of the glass fiber of the middle member with an outer covering of the glass fiber and impregnating the covered member with a thermosetting resin and hardening the impregnated member. The glass fiber reinforced panel produced has excellent fire retardant and water repelling properties, has improved compressive strength and does not deform or delaminate easily.

FIELD OF INVENTION [0001] The present invention relates to a continuous process for preparing 4-aminodiphenylamine by coupling aniline with nitrobenzene in the presence of tetramethylammonium hydroxide (hereinafter referred as TMAH) as a base using suitable continuous reactors. The present invention also relates to improved stability of TMAH in the presence of aniline and in particular in a coupling reaction product used for a 4-aminodiphenylamine manufacturing process. PRIOR ART [0002] 4-Aminodiphenylamines are widely used as intermediates in the manufacture of their N-alkylated derivatives which have utility as antiozonants and antioxidants, as stabilizers for monomers and polymers, and in various specialty applications. For example, reductive alkylation of 4-aminodiphenylamine (hereinafter referred as 4-ADPA) with methyl isobutyl ketone provides N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (hereinafter referred as 6PPD), which is a useful antiozonant for the protection of various rubber products. [0003] 4-Aminodiphenylamines can be prepared in various ways. An economically attractive and green synthetic route is the coupling reaction of aniline with nitrobenzene in the presence of a base, specially TMAH, followed by catalytic hydrogenation of the reaction product in the presence of water, as disclosed, for example, in U.S. Pat. No. 5,117,063 (Stern et. al.; hereinafter “the '063 patent”), U.S. Pat. No. 5,608,111 (Stern et al., hereinafter “the '111 patent”), U.S. Pat. No. 5,739,403 (Reinartz et al.; hereinafter “the '403 patent”) and U.S. Pat. No. 6,140,538 (Rains et al; hereinafter “the '538 patent”). [0004] The '111 patent describes a process for the preparation of an optionally substituted 4-ADPA wherein optionally substituted aniline and optionally substituted nitrobenzene are reacted in the presence of a base in a coupling reaction, followed by catalytic hydrogenation after addition of water to the coupling product. The hydrogenation catalyst, which typically is a supported noble metal catalyst, is removed from the hydrogenation reaction mixture, the organic phase is separated in order to isolate the 4-ADPA, and the aqueous phase, which contains the base, is returned to another cycle of the initial reaction mixture. In working examples, aniline and nitrobenzene are reacted in the presence of TMAH as a base, and water and aniline are azeotropically removed during the coupling reaction. [0005] The '403 patent describes a process for a coupling reaction comparable to that of Example 13 of the '111 patent, followed by catalytic hydrogenation, where the amount of water added prior to hydrogenation is 25 to 80 wt. % relative to the weight of the coupling reaction mixture. Example 1 of the '403 patent is distinguished from Example 13 of the '111 patent on the basis that it requires a 4-hour hold period, with continued distillation for completion of the coupling reaction of aniline and nitrobenzene in presence of TMAH, after completion of nitrobenzene addition. After the hydrogenation, toluene is added, the catalyst is filtered, and the organic and aqueous phases are separated. In Example 1 of the '403 patent, it is stated that, “Analysis of the aqueous phase shows that 99.7% of the introduced tetramethylammonium hydroxide may be isolated. The resultant aqueous phase may be returned to the reaction without loss of reactivity.” [0006] The '538 patent teaches that by distilling out more aniline-water at the end of the coupling reaction, TMAH decomposition is substantially enhanced, and hence the process becomes economically unattractive. The '538 patent emphasizes the thermal stability of TMAH by highlighting a minimum moisture content requirement for the reaction mass at the start and end of the coupling reaction. Besides this aspect, most of the embodiments of the invention described in the '538 patent are similar to those of the earlier the '111 and '063 patents. Both the '111 and '538 patents describe formation of water-aniline azeotrope, in the distillation during the coupling reaction, see e.g. column 4 lines 10-39 of the '538 patent. [0007] The '111 patent prescribes the water to base molar ratio at the start of the coupling reaction, but is silent about the water to base molar ratio at the end of the coupling reaction, though it specifies the modes of addition of nitrobenzene and removal of water aniline mixture during the coupling reaction stage; (see e.g. Example 13 of the '111 patent). [0008] The '538 patent emphasizes that the water to base molar ratio at the end of the coupling reaction should be 0.3:1 as per Example 13 of the '111 patent and Example 1 of the '403 patent and acknowledges that there could be decomposition of the TMAH at this ratio. This conclusion, however, is not supported by experimental evidence but instead appears to be based on an assumption that during distillation, an aniline-water azeotrope of a fixed composition of water:aniline 86.4:13.6 w/w is removed as the distillate. [0009] The literature provides information about the azeotropic compositions of aniline and water, as given in Table 1 (Azeotropic Data III, Compiled by Lee H. Horsley, Dow Chemical Co., Advances in Chemistry Series 116, American Chemical Society, Washington D.C., 1973, ISBN 841201668, pg 28): [0000] TABLE 1 Azeotropic compositions of aniline and water at different temperatures Temperature wt % of water in the (° C.) azeotropic composition 41 86.6 46 84.0 75 81.8 90 80.5 [0010] In another reference, the mole fraction of water in water—aniline azeotropic mixture at 99° C. is reported to be 0.96 (Azeotropic Data, by J. Gemhling, J. Menke, K. Fischer, J. Krafczyk, 1st Edition, Vol 2, page 1129, VCH Publishers Inc. New York, 1994, ISBN 3-527-28671-3). If this is converted to weight %, the composition comes out to be 82.3 weight % of water. This is relatively close to the values reported in Table 1. From Table 1, it is clear that the azeotropic composition contains 81.8% water by wt. at 75° C. and considering this value, the water to base molar ratio as per example 13 of the '111 patent at the end of coupling reaction is calculated to be about 0.6:1. Hence, calculation of the water to base molar ratio of example 13 of the '111 patent based on the assumption that the distillate is an azeotrope of aniline and water in the ratio of 86.4:13.6 is incorrect. [0011] The innovation claimed in the '538 patent is that the water to base molar ratio should be not less than about 0.6:1 at the end of the coupling reaction, in order to avoid the decomposition of TMAH. The stability data of the Tetramethylammonium (hereinafter TMA) salts of 4-nitrosodiphenylamine (hereinafter “4-NODPA”) and 4-nitrodiphenylamine (hereinafter “4-NDPA”) is not provided in the '538 patent and does not appear to be available in literature for the experimental conditions of the '538 patent. Also the respective hydration states of 4-NODPA and 4-NDPA are also not mentioned. Thus, the water which is remaining at the end of the coupling reaction, the amount of the water that is bound with the TMAH and the amount of free water is not addressed. In the absence of this information, the decomposition of TMAH in the reaction mixture at the end of the coupling reaction cannot be conclusively determined. [0012] It is well known in the literature that there are three basic types of reactors: (a) batch reactors, (b) plug flow reactors, and (c) mixed flow reactors (Chemical Reaction Engineering, O. Levenspiel, Third edition, John Wiley and Sons, 2001, ISBN 9971-512-41-6 page 90). The book explicitly states that: “In a batch reactor, the reactants are initially charged into a container, are well mixed, and are left to react for a certain period of time. The resultant mixture is then discharged. This is an unsteady state operation where composition changes with time”. The plug flow reactor and mixed flow reactor are characterized by the fact that there is a continuous flow of both fluid reactants into the reactor and products out of the reactor. The plug flow reactor, as well as the mixed flow reactor, is operated at steady state (page 94, 101). This implies that compositions of streams going into the reactor and coming out of the reactor as well as at any point within the reactor do not change with time. [0013] In the '538 patent it is mentioned that “The process steps of the present invention for the preparation of 4-aminodiphenylamines may be conducted as batch processes or they may be performed continuously using means and equipment well known to the skilled person.” See col. 9, lines 52-54 of the '538 patent. Moreover the '538 patent defines the start and end of the process in terms of a “point in time.” See col. 5, lines 43 and 46 of the '538 patent. This implies that process parameters, such as the composition within the reactor and the composition of the distillate change with time. As per the aforementioned description of batch vs. continuous processes, the process description given in the '538 patent and the corresponding claims are applicable to batch process only. Further, there are no working examples given in the '538 patent showing that the described process steps can be conducted in a continuous manner. Hence, this suggests that the results reported in the patent are applicable to batch processes. [0014] U.S. Pat. Nos. 7,084,302, 7,176,333, 7,235,694 and 7,989,662 etc. describe preparation of 4-ADPA, in a continuous manner, by reacting aniline with nitrobenzene in the presence of a base and hydrogenating the mixture, followed by refining the reaction mixture. However, for coupling of aniline and nitrobenzene, complex base catalyst is used instead of TMAH. The complex base is defined as a mixture of a tetra alkyl ammonium hydroxide, an alkali metal hydroxide and a quaternary ammonium salt in various molar ratios. This complex base catalyst is said to be stable as compared to TMAH alone, particularly when there is a low water to base molar ratio at the end of coupling reaction. Also, as per the teachings of these patents that water content in the reaction mass is always relatively high and the water content is not carefully controlled in the coupling reaction. Moreover, instead of a noble metal catalyst, a powdery composite catalyst comprising nickel, aluminum and a transition metal such as Fe, Cu, Co etc. is used for hydrogenation of the aniline-nitrobenzene coupling product by employing a low temperature continuous reduction process. Decomposition of TMAH is not addressed in any of these steps. [0015] One objective of the present invention is to develop a 4-ADPA process which will be of low capital cost, have a high process efficiency in terms of volume productivity and process consistency, based on the coupling reaction of aniline and nitrobenzene in the presence of TMAH. [0016] Batch processes have the following distinct disadvantages: a) capital expenditure is high since the batch size decides the volume/size of equipment required for each unit operation; b) voluminous equipment also requires extensive civil work and complicated interconnecting piping; c) quality consistency requires very close process monitoring with a backup system of sophisticated process control and analytical instrumentation; d) high energy cost since each batch undergoes through heating and cooling cycles; e) high maintenance cost since each piece of equipment goes through repeated start/stop modes depending on the cycle time; f) low capacity utilization since the batch processes require “In between batches maintenance” and predictive maintenance of a batch process is difficult. Normally batch processes do not operate at >85% plant capacity. Hence, a batch process leads to higher variable cost of manufacturing and a reduced business advantage in comparison to a continuous process. On the other hand, one of the distinct advantages of a batch process is 100% conversion of raw materials to finished product. Theoretically, a continuous process requires infinite reactors in series to achieve 100% conversion. However, if the process need not to achieve 100% conversion in a reaction and the unconverted raw materials can be easily separated and recycled, without reducing process efficiency, significantly increasing unit cost and without detrimental effects on the final product quality, a continuous process is preferred over a batch process. A basic prerequisite, however, is that the reaction chemistry must permit adoption of continuous process. [0017] In the development of a commercial process for manufacture of 4-ADPA, using a coupling reaction of aniline with nitrobenzene in the presence of TMAH, it was found by the inventors that a continuous process can be employed to significantly increase the volume productivity of the process, relative to the corresponding batch process and thus that a batch process and requires very large reactors in the coupling and subsequent basic reduction steps. [0018] Also, the coupling of aniline with nitrobenzene in the presence of TMAH produces phenazine and azobenzene as by-products. Azobenzene can be reduced to aniline by catalytic hydrogenation and then can be recycled to the process. However, phenazine, is a troublesome by-product which poses a lot of difficulties, viz. considerable energy intensive fractional distillation is required to separate this by-product from the finished product, though formed in a relatively minor quantity, due to its high boiling point as well as its high melting point. For example, phenazine was found to solidify in the upper section of the distillation column due to its high melting point which makes the distillation operation very difficult. Also Phenazine is not desirable in the finished product. Further, methods for decreasing the formation of phenazine have not been addressed in the prior art. [0019] Another objective of the present invention is to achieve better stability of TMAH under the continuous process conditions than that reported earlier and to carry out the coupling reaction without a limitation on the water to base molar ratio at the end of the coupling reaction or in the product of the coupling reaction as stated in the earlier patents, so as to harness the full advantage of carrying out the coupling reaction in continuous manner. TMAH stability in the presence of water is documented in the literature (See e.g. W. Kenneth Musker; J. Chem. Edn., vol. 45, pp. 200-202, (1968) and W. Kenneth Musker; J. Am. Chem. Soc., vol. 86, pp. 960-961(1964)). [0020] A further objective of the present invention is to optimize the water to “free TMAH” or “unbound TMAH” molar ratio, rather than the water to total base (free TMAH+all other TMA salts including TMA salts of 4-NODPA & 4-NDPA) molar ratio in the product of the coupling reaction in order to minimize the decomposition of TMAH. [0021] None of the prior art patents addresses how to carry out the coupling reaction with high efficiency using a minimal charge of TMAH so that without affecting coupling reaction efficiency, negligible free (unreacted) TMAH remains, thus substantially reducing TMAH decomposition at the end of the coupling reaction even when the water to base molar ratio is very low. [0022] The other objective of the invention is to achieve high productivity by carrying out the coupling reaction in a continuous manner in continuous flow reactors with minimal TMAH decomposition even when the water to total base molar ratio is significantly below 0.6:1. SUMMARY OF THE INVENTION [0023] Accordingly, in brief summary, one embodiment of the present invention is a process which comprises one or more of the steps of: [0024] i) reacting aniline and nitrobenzene in the presence of water and TMAH as a base, in a continuous manner by feeding the reactants to a series of continuous flow reactors, while continuously distilling off an aniline-water mixture under reduced pressure such that the water to total base molar ratio is less than 0.6:1 at the flow reactors outlet, and the water to unbound TMAH molar ratio is about 4:1 in the reaction product of the coupling reaction, to thereby produce 4-nitrodiphenylamine and/or 4-nitrosodiphenylamine and/or salts thereof; [0025] ii) adding water and hydrogenating the reaction product from step i) in the presence of a suitable hydrogenation catalyst to produce a 4-ADPA-containing reaction product; [0026] iii) separating the hydrogenation catalyst from the reaction mixture to obtain an aqueous phase containing the base catalyst, and an organic phase containing 4-ADPA as the major component; and optionally recycling the recovered hydrogenation catalyst used in step ii) and [0027] iv) separating the organic phase from the aqueous phase and subsequently purifying the organic phase to isolate 4-ADPA and recover excess aniline for recycle in step i), and also recycling the aqueous phase containing the regenerated TMAH to step i) after optional further purification. [0028] Other embodiments of the present invention encompass methods for enhancing the stability of TMAH in aniline and/or in the coupling reaction mixture using different water contents and process conditions. [0029] In other embodiments of the present invention, reductive alkylation of 4-ADPA made from the continuous process is carried out after suitable purification of the 4-ADPA. The reductive alkylation step can be employed for production of commercial antiozonants such as 6-PPD. DETAILED DESCRIPTION OF THE INVENTION [0030] In a first aspect, the present invention is directed to a continuous process for making 4-ADPA that is economically attractive. More particularly, in a first embodiment the invention provides a process in which TMAH, excess aniline and the hydrogenation catalyst are recycled in a manner which makes the process economically attractive. It has been found that the TMAH and the aniline can be recycled with a minimum loss of reactivity for coupling of aniline with nitrobenzene and that the hydrogenation catalyst can be recycled with a minimum loss of reactivity for hydrogenation, by controlling the level of impurities in the recycle streams and by carefully controlling the amount of water in relation to the base during the reaction steps. [0031] The inventors have found that a larger amount of phenazine forms when the coupling reaction is carried out in a batch process, where nitrobenzene was added in a controlled manner, as compared to a continuous process, since the objective of the batch process was to convert all the nitrobenzene. Based on this objective, the reaction time is fixed and the production of a larger amount of phenazine necessarily results. A reduction of the batch reaction time may not reduce the impurity level due to: a) the availability of pool of reactants in the batch reactor and b) the continuous change in the concentrations of the reactants over time which necessarily occurs in a batch reaction. Both of these conditions are absent in a continuous process. [0032] Carrying out the coupling reaction in a continuous manner resulted in nearly 50% less formation of phenazine and, due to the inherent nature of a continuous process the concentrations of the reactants remained constant thereby providing a highly predictable reaction. In a continuous process the contact time between the raw materials can be altered by changing the feed rate of one or more reactants to the continuous flow reactors in order to reduce the degree of formation of impurities such as phenazine. Thus, the combination of using a continuous process and selection of appropriate feed rates can be used to avoid or reduce the need for elaborate and energy intensive separation steps subsequent to the coupling reaction. [0033] Based on the above-mentioned advantages of the continuous process it has been found that significant improvements can be achieved by adoption of a series of continuous flow reactors. This process design concept provides extensive flexibility in varying process parameters namely reaction rate, raw material feed rate, heat input, reaction pressure, ratios of raw materials etc. It was observed that phenazine can be reduced by 50% in a continuous process as compared to the amount formed in the prior art batch process. This also results in a lower conversion (e.g. <95%) of nitrobenzene to the desired product as compared to the batch process and relatively more formation of azobenzene by-product, which can be converted to aniline and recycled to the process without loss of raw material efficiency. The continuous process also provides flexibility to recover some of the recyclable raw materials at the reaction stage without loading the subsequent hydrogenation stage with unnecessary materials. Lower residence time at particular moisture contents, as well as control of the charge of TMAH, also reduces TMAH degradation which is not possible in the batch process due to requirement of a fixed reaction time and the relatively longer period required for reactor unloading after coupling reaction. [0034] A study of the distillate of the reaction of Example A of the present application was carried out and it was found that the distillate of different reaction mixtures under low pressure as well as under atmospheric pressure, contained varying compositions of aniline—water. This study demonstrates that the aniline-water mixture is distilled as a mere mixture based on their respective mole fractions and relative volatility and not as an azeotrope as previously thought in the prior art. The results of this study are shown in Table 2 of Example A. [0035] On reproducing Example 13 of the '111 patent (Example B) and the similar Example 1 of the '538 patent several times, it was found that the water to base (base is considered as per the definition given in the '111 and '538 patents) molar ratio at the end of the coupling reaction is always more than 0.6 (actually ˜1.2 to 1.3). See Table 3 of Example D below. [0036] Example 6 of the '538 patent highlighted that whenever the water to base molar ratio at the end of the coupling reaction goes below 0.6:1 there is substantial base decomposition. However, on repeating this Example 6 (Column 15, lines 19-67 and Table 2 at column 16, lines 1-10 of the '538 patent), it is found that water to base molar ratio remains at about 1.1-1.2 and never goes below 1, since virtually no distillation occurs once this ratio is achieved under the specified reaction conditions (temperature 75° C. and pressure 57 mm of Hg), even by extending the hold period to 4 hrs. TMAH decomposition at the end of nitrobenzene addition as well as at the end of the hold period was comparable and was only up to about 1% or less (Example D, Table 3 below). Total Base in reaction mass after coupling reaction, is analyzed by titration method and method showed ˜1% variation and hence to understand the extent of decomposition of TMAH, N-methyl aniline formation was measured by HPLC which, although not equivalent, showed extent of TMAH decomposition in reaction mass. In all the experiments in Table-3, results showed N-methyl aniline formation varying within a narrow range of low value, indicating relatively negligible decomposition, which complemented the less decomposition of TMAH in the reaction product at the end of coupling reaction. It was found that the water content in the reaction mass can only be reduced when the pressure is further reduced to 10-15 mm of Hg pressure and that the TMAH decomposition is much less than that mentioned in Table 2 of Example 6 of the '538 patent. [0037] Further, holding a thermally unstable compound (TMAH) for prolonged reaction time at higher temperature and without reduction of pressure by implementing a hold period beyond 30 minutes in a batch process does not make sense if TMAH decomposition is a primary consideration. There is a major limitation when the reaction is carried out in a batch manner in a large volume reactor, i.e. the hydrostatic head of the liquid increases the overall boiling point of the reaction mass, thereby limiting distillation. In all the aforementioned working examples of the '111 and '538 patents, the initial TMAH to nitrobenzene molar ratio is 1.05 and hence there is always some free (unbound) TMAH present in the reaction mixture that is susceptible to decomposition, whenever the moisture content of the reaction mixture drops below a certain value. This free TMAH and the decomposition thereof has not been adequately addressed in the prior art. [0038] The present inventors have found that TMAH is relatively stable in the presence of aniline and water, particularly at a water to TMAH mole ratio of about 4:1 and that TMAH decomposition occurs when this ratio is reduced to 3.5:1 or less, with concomitant formation of a proportional amount of N-methyl aniline which results from the decomposition of TMAH in the presence of aniline, as shown in Table 4 below. The TMAH decomposition can be decreased by reducing the hold period. As shown in the working examples, the stability of TMAH in the presence of aniline was evaluated by stage-wise distillation of water from a mixture of aqueous TMAH (35% w/w) in aniline to obtain a water to TMAH molar ratio of about 4:1, then about 3.5:1 and then about 3:1, successively at 75° C. under 55 mm Hg pressure (similar to the process conditions mentioned in the first TMAH concentration step of Example 13 of the '111 patent as well as Example 1 of the '538 patent) and subsequently maintaining the reaction mass under atmospheric pressure for a hold period of 4 hours [0039] The results shown in Example 2, Table 4 and also FIG. 1 indicate that at water to TMAH molar ratio of about 4:1 and about 3.5:1, N-methyl aniline formation is <500 ppm while at a water to TMAH ratio of about 3:1, TMAH decomposition is up to 1000 ppm at the end of the 4 hour hold period. At the end of a 4 hour hold period, TMAH decomposition was found to be less than 2% for water to TMAH molar ratios of 4:1 and 3.5:1, whereas TMAH decomposition was 3.6% for water to TMAH molar ratio of 3:1. The proportional N-methyl aniline formation with respect to time, confirmed the extent of TMAH decomposition in each case. Therefore, it can be inferred that for any of the above water to TMAH molar ratios, TMAH decomposition can be controlled by reducing the hold time and use of a water to TMAH molar ratio of 4:1 is preferable for better stability. [0040] Also, TMAH 4H 2 O, TMAH 3.5H 2 O and TMAH 3H 2 O were made and added to the same quantity of aniline and held at 80° C. for 4 hours under atmospheric pressure and the TMAH decomposition was evaluated by analyzing TMAH and N-methyl aniline. The results are summarized in Example E, Tables 5-6. It was found that TMAH solutions with an initial water to TMAH molar ratio of about 4:1 and about 3.4:1 were fairly stable in the presence of aniline at about 80° C. for up to 4 hours of hold time, which finding was also supported by the measured quantity of N-methyl aniline formation. However, TMAH decomposition increases as the water to TMAH molar ratio decreases to about 2.9:1 which resulted in a considerable increase in N-methyl aniline content. [0041] Also, solid TMAH.4H 2 O and TMAH.3H 2 O were individually heated in the presence of aniline at 80° C. and the evolved vapor was analyzed by a Headspace GC analyzer. The details of these studies on thermal stability of TMAH in aniline are narrated in the working examples given below. The results are given in Example F, Tables 7-8. The results show that N-methyl aniline formed which indicates that TMAH decomposition occurred. N-methyl aniline formation is relatively higher for the sample having a water to TMAH molar ratio of about 3:1 than for the sample with a water to TMAH ratio of about 4:1. This relatively higher decomposition of TMAH at a water to TMAH molar ratio of about 3:1 is also supported by measurement of trimethylamine gas by GC analysis, which gets formed during TMAH decomposition. [0042] All these studies reveal that TMAH is fairly stable when the water to TMAH molar ratio is about 4 and that the rate of TMAH decomposition increases as the water to TMAH molar ratio is lowered to about 3.5 and that the TMAH decomposition significantly increases in the presence of a water to TMAH molar ratio of about 3:1. [0043] The products of the aniline-nitrobenzene coupling reaction carried out in the presence of TMAH are known to include a mixture of TMA salts of 4-NODPA and 4-NDPA and some by-products like azobenzene and phenazine. Thus, tetramethyl cation is stoichiometrically bound at the end of the coupling reaction to 4-NODPA and 4-NDPA. It is found that, at the end of the coupling reaction, depending upon the conversion and selectivity based on nitrobenzene and the moles of TMAH added with respect to the moles of nitrobenzene, some TMAH may remain “free” or “unbound”, i.e. some TMAH may remain that is not bound in salts of 4-NODPA or 4-NDPA. For example, in the case of Example 13 of the '111 patent, which employs a TMAH to nitrobenzene molar ratio of 1.05 and may exhibit about a 94% selectivity of nitrobenzene to TMA salts of 4-NODPA+4-NDPA, the free TMAH at the end of reaction works out to be ˜0.11 mole. [0044] The present inventors have surprisingly found that the free TMAH, which is present in the reaction product of the coupling reaction at the flow reactors outlet, has an important bearing on the total decomposition of TMAH. Studies of the coupling reaction showed that the decomposition of TMAH can be reduced as long as about 3.5 to 4 moles of water or preferably 4 or more moles of water are present in the reaction mass with respect to the amount of free TMAH remaining in the reaction mass in the reaction product of the coupling reaction. Contrary to the findings of Example 6 of '538 patent, the present inventors have found that water to base molar ratio can be reduced to below 0.6:1 without a significant change in TMAH decomposition. The inventors have found that this can be effectuated by continuing the reaction up to completion of nitrobenzene addition, followed by a 30 minute hold period and then reducing the pressure to 10-15 mm of Hg at 75° C. to effect further distillation and thereby reduce the water to base molar ratio to below 0.6. The results surprisingly show negligible decomposition of TMAH (<1%) and are confirmed by estimation of N-methyl aniline formation in the reaction (See Example D, Table 3 below). [0045] As shown in experiment no. 4 of Table 3, by carrying out an experiment similar to example 13 of the '111 patent and further reducing the pressure, more water can be distilled out of the reaction mass until about 3.5 to 4 moles water remains with respect to the amount of free TMAH in the reaction mixture, which works out to be water to base molar ratio of about 0.38 to 0.44 (found to be 0.42 in experiment 4 of Table 3), since only 0.11 mole of free TMAH remains in this particular reaction mass in the reaction product of the coupling reaction. According to the '538 patent, the total base in the reactor is to be considered as the amount of free base and/or base included in the 4-nitroso- and/or 4-nitrodiphenylamine salts of TMA. See e.g. col. 5, lines 62-65 of the '538 patent. [0046] Stability studies of TMAH in aniline, as shown in the aforementioned Examples D, E and F also support this finding. This finding is also in agreement with the step of concentrating TMAH in aniline, with a water to TMAH molar ratio of at least about 4:1 at the start of the coupling reaction, without much decomposition under the reaction conditions, as mentioned in the '111 and '538 patents. [0047] The amount of water that should be allowed to remain in the reaction product of the coupling reaction at the flow reactors outlet can thus be determined to be the amount of water required for a molar ratio of water to free or unbound TMAH (i.e. TMAH not bound as salt of 4-NODPA or 4-NDPA) of about 3.5-4:1, thus allowing the overall water to total base (the total of free TMAH and bound TMA salts) molar ratio to be reduced to significantly less than 0.6:1, without decomposition of TMAH. [0048] Further experiments as shown in Example 3, following Example 13 of the '111 patent as well as Example 1 of the '538 patent, were carried out wherein nitrobenzene was added over 3 hours at 55 mm Hg followed by a 30 minute hold period and then subsequently reducing the pressure to about 10-20 mm, whereby the molar ratio of water to the total TMAH fed to the reaction was reduced to about 0.4-0.45, without any significant decomposition of TMAH i.e., <1% (the commercially acceptable level as mentioned in Example 6 of the '538 patent). This result is confirmed by N-methyl aniline estimation in the reaction mass. [0049] Further experiments in Example 3, Table 9, with a lower TMAH charge i.e., lowering the TMAH:nitrobenzene molar ratio fed to the reaction from 1.2:1 as in the prior art examples to as low as 0.9:1, resulted in lower quantities of free TMAH remaining in the reaction product of the coupling reaction and about 4 mole equivalent of water or more, relative to free TMAH were found in the reaction product. Thus, by ensuring a lesser amount of free or unbound TMAH in the reaction product of the coupling reaction, an even lower water to base molar ratio can be achieved without significant TMAH decomposition. For example, an initial nitrobenzene to TMAH molar ratio of 1:1 or less can allow a final molar ratio of water to total base fed to the reaction of less than 0.3:1 while preserving a commercially acceptable level of TMAH decomposition i.e., <1%. [0050] Further experiments were carried out by following example 13 of the '111 patent and by charging less moles of TMAH relative to nitrobenzene i.e., using nitrobenzene:TMAH molar ratios varying between 0.9 to 1:1, and further concentrating the reaction mass at the end of hold period by lowering the pressure (about 10 mm Hg pressure at ˜75° C.). The molar ratio of water to total base in the reaction mass was found to be about 0.25-0.45, with negligible TMAH decomposition. [0051] Results of the foregoing experiments are summarized in Example 3, Tables 9-10. It is seen that as the TMAH to nitrobenzene molar ratio decreases, the amount of free TMAH in the reaction product of the coupling reaction is reduced and therefore, a water to base molar ratio of <0.6 can be achieved without much decomposition of TMAH. Also, a small increase in azobenzene formation is seen, as the amount of base with respect to nitrobenzene is decreased. [0052] TMAH decomposition also depends on the residence time at the reaction temperature (˜75-80° C.) since TMAH is subject to thermal decomposition. The experiments demonstrate that a continuous process provides a distinct advantage over batch process, since in the continuous process the residence time at high temperature can be reduced as compared to a batch process by using appropriate process equipment such as a continuous plug-flow reactor, especially at the end stage of coupling reaction. This type of device can also be suitably heated in different zones so as to heat the coupling reaction mass under vacuum with efficient heat control. Thus, the coupling reaction can be carried out in a continuous manner with an initial charge of a molar ratio of TMAH to nitrobenzene in the range of 0.85:1 to 1.1:1, or, more preferably, in the range of 0.9:1 to 1:1. [0053] Further, the coupling reaction can be completed in a continuous plug flow reactor under suitable temperature and pressure conditions selected for minimal heat exposure of TMAH. For example, the final stage of the reaction can be conducted at a low pressure in the range of 1-25 mm, or, more preferably, between 1-15 mm while controlling the reaction mass temperature to remain below 80° C. or, more preferably, below about 75° C., in order to ensure minimal decomposition of TMAH and achieve a concentrated reaction mass having a water to TMAH molar ratio less than 0.6:1, preferably less than about 0.4:1. Because of an efficient heat and mass transfer rate, the reaction is easily completed in a continuous manner in a series of reactors and hence better process efficiency, as compared to a batch process, can also be achieved. [0054] The reaction mass may then be sent to a hydrogenation step after mixing with an adequate quantity of water to produce 4-ADPA and regenerate TMAH for recovery and recycle. The coupling reaction mass at the end of concentration step comprises of about 0.5-0.55 weight % phenazine with respect to 4-ADPA equivalent. [0055] Further studies on the coupling reaction of aniline and nitrobenzene in the presence of aqueous TMAH in pilot scale in a continuous manner using a combination of flow reactors reveals distinct advantages in terms of consistency of the process, lower energy consumption, and easy operability. In the final concentration step, while reducing water content, the reaction mass is fed through a continuous plug flow reactor under controlled conditions so as to obtain a concentrated reaction mass with a limited amount of free TMAH and a water to base molar ratio of <0.6, preferably, less than about 0.4 (Example 4). [0056] Also, the coupling reaction goes to completion with only a slight stoichiometric excess of TMAH due to the high rate of mass and heat transfer in the continuous plug flow reactor, which provides another advantage relative to a batch process. Hence, with a slight excess of free TMAH beyond the stoichiometric amount, relative to nitrobenzene feed, not only does the reaction go to completion, but also the reaction mass can be concentrated to achieve the water to base molar ratio much less than 0.6. The concentrated coupling mass can be easily hydrogenated by adding an appropriate quantity of water without any adverse effect on the catalyst efficacy, reaction time, and stability of TMAH in the hydrogenation step. The ability to concentrate the reaction mass reduces the mass throughput in the subsequent steps (i.e. hydrogenation) by removing more of the aniline from the reaction mass than in the prior art batch process, thereby improving process efficiency. [0057] Hence, it is possible to obtain a water to base molar ratio less than 0.6:1 without substantial decomposition of the TMAH base. Relatively, more N-methyl aniline is formed during distillation at the end stage of coupling reaction in the batch process than in the continuous process, due to the higher residence time at higher temperature (˜80° C.) since the continuous process in plug flow reactor requires a significantly reduced residence time and thus minimizes TMAH exposure at higher temperature. Moreover, the reaction goes to completion with only a slight excess of TMAH over the stoichiometric requirement due to the high heat and mass transfer rate. Finally, more aniline can be removed by concentration of the coupling reaction mass at the flow reactors outlet, thereby reducing the amount of aniline fed to subsequent steps in the process, thereby increasing process efficiency. [0058] Crude 4-ADPA, obtained by carrying out the coupling reaction in aforementioned continuous manner, followed by hydrogenation after adding adequate water, with subsequent separation of the organic and aqueous phases followed by purification provides a highly efficient process for the manufacture of highly pure 4-ADPA (>99% purity). The purification steps may include, for example, fractional distillation and an azobenzene reduction step. The substantially pure 4-ADPA can then be easily converted to a rubber antiozonant such as 6-PPD and similar antiozonants by well-known reductive alkylation methods using a suitable ketone such as methyl-isobutyl ketone (MIBK). [0059] From the foregoing description, one skilled in the art can ascertain the essential characteristics of this invention and without departing from the spirit and scope thereof can make various changes and modifications of the invention to adapt it to various usages and conditions. [0060] The invention is illustrated by the following examples; EXAMPLES Example A Distillation of Aniline and Water Mixture to Study Formation of any Azeotrope Under the Prior Art Reaction Conditions [0061] This example illustrates that distillation of a mixture of aniline and water under the prior art reaction conditions leads to different compositions of aniline and water in the distillate and does not provide a distillate which is an aniline/water azeotrope as taught in the prior art patents related to 4-ADPA production. Different compositions of aniline and water were subjected to distillation at reduced pressure, i.e., 55 torr, as used in the Example 13 of the '111 patent, as well as at atmospheric pressure (about 1 bar). The distillate, up to 20 to 70 volume % of the mixture, was collected in each case in a manner which maintained some quantity of the minor component in the bottoms. The results are shown in Table 2 below: [0000] TABLE 2 Aniline - water mixture distillation study: Feed for Distillation Distillate Input Output Input composition Output composition Weight Water Aniline Weight Water Aniline Gm % % gm % % At 55 torr 1 300 70 30 93.45 81.2 18.8 2 300 80 20 65.39 83.7 16.3 3 300 86.6 13.4 209.68 85.2 14.8 4 300 90 10 54.25 88.9 11.1 At 760 torr 1 300 81 19 232.64 80.7 19.3 2 300 86.6 13.4 217.74 83.5 16.5 Example B Conventional Coupling Reaction Between Aniline and Nitrobenzene [0062] This example illustrates the results obtained when laboratory experiments were conducted similar to Example 13 of the '111 patent. [0063] The coupling reaction was carried out in a 2 liter glass round bottom flask (RB flask) equipped with a stirrer (½ moon blade Teflon™ stirrer), Dean-Stark condenser, a thermometer, Teflon™ baffle and a dropping funnel for nitrobenzene addition. Initially about 25% aqueous TMAH solution (24.8% w/w, 680.7 gm, 168.8 gm on 100% basis, 1.86 moles) was charged into the RB flask. Water was removed by distillation under reduced pressure at 55 mm Hg to obtain an aqueous TMAH solution of 35% w/w TMAH. During this stage the temperature increased to 50-53° C. Aniline was charged (1003.9 gm, 10.76 moles) into the reactor and the distillation was continued under reduced pressure at 55 mm Hg. Water and aniline were removed by distillation until the molar ratio of water to TMAH was about 4:1. During this process the temperature of the reaction mass increased to 70-73° C. [0064] After attaining the required molar ratio of water to base, nitrobenzene (218.3 gm, 1.77 moles) was added continuously over a period of 180 minutes. During the nitrobenzene addition water and aniline were continuously removed from the reaction mass by distillation under reduced pressure at 55 mm Hg. The reaction mass was maintained at about 75° C./55 mm Hg for 0.5 hour, after completion of nitrobenzene addition. The reaction end point was determined by HPLC analysis by monitoring the conversion of nitrobenzene. The total reaction time was about 5.5 hours and a typical selectivity, determined by HPLC at the end of the hold period at nitrobenzene conversion of 99.95% was 4-NODPA—86.62%, 4-NDPA—5.84%, azobenzene—6.3% and phenazine—1.13%. The moisture content of the reaction mass at the end of the batch was found to be 3.16% by the Dean stark method (and 3.21% by material balance) and the water to total base molar ratio in the reaction mass at the end of the coupling was found to be about 1.22 (by material balance 1.24). [0065] Note 1: [0066] HPLC Assay: Reverse phase HPLC was used to analyze the reaction mixtures. [0067] Analytical parameters: Column: 5 Lichrosphere RP-18e 250×4.6 or equivalent [0068] HPLC: Agilent 1200 with DAD coupled with Chemstation Software or equivalent [0000] Mobile phase A: methanol HPLC grade Mobile phase B: To a solution of 75% (v/v) water and 25% (v/v) methanol add 0.2-0.3 ml/liter of triethyl amine and adjust the pH was adjusted to 6.5 to 7.0 using H 3 PO 4 . Calculations: Internal standard method [0069] Note 2: [0070] Dean Stark method: The material to be tested was heated under reflux with water immiscible solvent, which co-distils with water. A mixture of water and the solvent separates on condensing the vapors; the heavier water layer was collected in a graduated receiving tube, the solvent running back into the flask. From the amount of water collected, moisture content calculations were done. Example C Reduction of the Coupling Reaction Product [0071] This example illustrates reduction of 4-NODPA and 4-NDPA in the coupling mass. [0072] In a 2 liter capacity autoclave was placed the coupling reaction mass at the end of the coupling reaction (900 gm) containing aniline (54%), 4-NODPA (25%), 4-NDPA (1.8%) (Both 4-NODPA and 4-NDPA exist in salt form), phenazine (0.3%), azobenzene (1.8%) and total TMAH (13.5%) (total TMAH includes both free TMAH and TMAH in salt form). All percentages are weight percentages. To this product was added water (307 gm) and noble metal catalyst (e.g. 5% Pd/C). The reaction mixture was heated at 80° C. under a hydrogen pressure of 15 kg/cm 2 . At the end of reduction (no hydrogen absorption, typically 30 minutes) the remaining 4-NODPA and 4-NDPA content was almost nil. HPLC gives 4-ADPA analysis which corresponds to at least 98 mole % of 4-NDPA and 4-NODPA. [0073] The reaction mass was filtered to separate hydrogenation catalyst, followed by separation of the organic and aqueous phases. The aqueous phase comprising TMAH and traces of organics was purified by hydrocarbon solvent extraction and other purification steps, followed by concentration to regenerate TMAH suitable for recycle. The organic phase was suitably washed with fresh water to remove any traces of TMAH, followed by as several purification steps namely fractional distillation and reduction under suitable process conditions to produce highly pure 4-ADPA. Examples 1 and D This Example Repeats Example 6 of the '538 Patent to Study the Decomposition of the Base (TMAH) as a Function of the Water to Total Base Molar Ratio at the End of the Coupling Reaction and after a Hold Period [0074] This example illustrates the effect of the hold period at the end of the coupling reaction on the water to total base molar ratio and TMAH decomposition to determine whether a water to base molar ratio below 0.6:1 can be obtained simply by holding the reaction mass for a given number of hours (Example D). It also illustrates the effect of a water to total base molar ratio below 0.6:1 on the TMAH decomposition, by adjusting the reaction conditions at the end of coupling reaction (Example 1). [0075] For Example D, three different experiments were conducted following the procedure given in Example 6 of U.S. Pat. No. 6,140,538, wherein nitrobenzene was added in 2 hours, 2.5 hours and 3 hours, each followed by a 4 hour hold period at 75° C. and 57 mm Hg pressure (equivalent to 76 mbar). [0076] In a typical reaction, the coupling reaction was carried out in a 2 liter glass round bottom flask (RB flask) equipped with a stirrer (½ moon blade Teflon™ stirrer), a thermometer, a baffle and a dropping funnel for nitrobenzene addition. Initially, an aqueous solution of TMAH (35.01% w/w, 485.66 gm, 170.03 gm on 100% basis, 1.87 moles) was charged into the RB flask. Aniline was then charged (995.92 gm, 10.68 moles) into the RB flask and distillation was continued under reduced pressure at 57 mm Hg. Water and aniline mixture was removed by distillation until the molar ratio of water to total TMAH was about 4:1. During this process the temperature of the reaction mass increased to 70-73° C. [0077] After attaining the required molar ratio of water to total base, nitrobenzene (218.99 gm, 1.78 moles) was added continuously over a given period i.e. 120 or 150 or 180 minutes. During the nitrobenzene addition, water and aniline were continuously removed from the reaction by distillation under reduced pressure at 57 mm Hg. The reaction mass was maintained at about 75° C./57 mm Hg for 4 hours after completion of nitrobenzene addition. [0078] The reaction mass was analyzed at the end of nitrobenzene addition and at the end of the hold period for nitrobenzene conversion by HPLC analysis. Also, the reaction mass was analyzed for TMAH content, N-methyl aniline, and moisture by titration, HPLC & Dean Stark techniques, respectively. [0079] In another experiment (Example 1), nitrobenzene was added over a period 2 hours as above, followed by a 0.5 hour hold period by keeping the reaction temperature at 75° C. and the pressure at 57 mm Hg. Distillation of the aniline and water mixture was then continued at ˜75° C. by decreasing the pressure gradually to about 15 mm Hg, so as to be able to obtain a water to total base molar ratio below 0.6. The reaction mass was analyzed for nitrobenzene conversion by HPLC analysis. Also, the reaction mass was analyzed for TMAH content, N-methyl aniline and moisture by titration, HPLC & Dean Stark techniques, respectively (Table 3) [0000] TABLE 3 N-Me aniline N-me aniline W/B in the W/B molar in the reaction molar reaction ratio - at the mass at the ratio - at mass at the end of end of the end of end of reaction (NB reaction (NB NB TMAH nitrobenzene addition + 4 hrs TMAH addition + 4 hrs Exp. addition Accountability addition hold) Accountability hold) No. Details M.B. D.S. (%) (ppm) M.B. D.S. (%) (ppm) 1 2 hr NB 1.77 1.72 100.4 6 1.14 1.16 99.30 85 Addn. + 4 hr hold 2 2.5 hr NB 1.76 1.75 100 5 1.27 1.30 100.32 71 Addn. + 4 hr hold 3 3 hr NB 1.69 1.62 100.6 16 1.14 1.17 100.6 58 Addn. + 4 hr hold 4 2 hr NB 1.47 1.56 100.4 20 0.33 0.42 99.8 329 Addn. + 0.5 hr hold + up to 15 mm hg M.B. = Material balance; D.S. = Dean Stark method; N-Me aniline = N-Methyl aniline Example 2 TMAH Stability, in the Presence of Aniline, Wherein Different Water to Total TMAH Molar Ratios were Obtained by Distilling Excess Water [0080] This example illustrates the effect of water to TMAH molar ratio on TMAH stability in the presence of aniline and also the effect of a hold period at elevated temperature on TMAH stability for certain water to total TMAH molar ratios. [0081] Experiments were conducted wherein aqueous TMAH along with aniline is concentrated by continuously distilling off an aniline and water mixture under reduced pressure so as to reach water to total base molar ratios of about 4:1, 3.5:1 and 3:1. After obtaining the specified water to total base molar ratio, the reaction mixture was held for 4 hours and was analyzed every hour for TMAH and N-methyl aniline contents. [0082] In a typical reaction, TMAH was concentrated in the presence of aniline in a 2 liter Glass Round Bottom flask (RB flask) equipped with a stirrer (½ moon blade Teflon™ stirrer), a thermometer, a baffle, and a dropping funnel for aniline addition. Initially an aqueous solution of TMAH (34.63% w/w, 491.27 gm, 170.13 gm on 100% basis, 1.87 moles) was charged into the RB flask. Aniline (1004.11 gm, 10.80 moles) was charged into the reactor and the distillation was continued under reduced pressure at 55 mm Hg. Water and aniline mixture was removed by distillation until a given initial molar ratio of water to TMAH was obtained. During this process the temperature of the reaction mass increased to 70-73° C. [0083] After attaining the required initial water to base molar ratio, the reaction mass was kept on hold at about 75° C. for 4 hrs. The reaction mixture was analyzed for TMAH content and for N-methyl aniline, as an indicator of the extent of TMAH decomposition, and the distillate was analyzed for water content. Results are summarized in Table 4. Also FIG. 1 depicts the increase in N-methyl aniline formation with time at different water to total base molar ratios. [0000] TABLE 4 Water/Base TMAH N-methyl aniline molar decomposition in the reaction ratio at the at the mass (ppm) end of end of 4 hrs during hold Exp. TMAH hold Hold (hrs) No. concentration (%) 0 1 2 3 4 1 4.08 1.6 24 72 83 145 213 2 3.53 1.0 36 148 263 370 489 3 3.15 3.6 49 332 437 614 849 Example E Stability of Solid TMAH in Aniline Having Varying Water Contents at 80° C. For Different Hold Times [0084] This example illustrates stability of solid TMAH at different water to total TMAH molar ratios, in aniline solvent and also the effect of hold period on solid TMAH stability for the given water to total TMAH molar ratio. [0085] Aqueous TMAH (˜35% w/w) was concentrated by continuously distilling and water under reduced pressure so as to reach water to total base molar ratios of about 4:1, 3.5:1 and 3:1. The TMAH samples thus prepared were heated to about 80° C. in aniline and held up to 4 hours at atmospheric pressure under a nitrogen blanket. Samples were analyzed every hour for TMAH and N-methyl aniline. The results are summarized in Tables 5 and 6. [0000] TABLE 5 Compositions of aniline-TMAH mixtures TMAH (gm) molar molar molar ratio-water ratio-water ratio-water Sr. Aniline to TMAH = to TMAH = to TMAH = No. Sample (gm) 4.07:1 3.38:1 2.86:1 1 Sample 1 151.3 47.1 — — 2 Sample 2 147.3 — 42.0 — 3 Sample 3 143.7 — — 39.77 [0000] TABLE 6 TMAH decomposition over time in terms of N-methyl aniline formation Water/Base TMAH N-methyl aniline molar ratio account- in the reaction at the end of ability mass (ppm) TMAH at the end during hold concen- of 4 hours Hold (hrs) Sample tration hold (%) 0 1 2 3 4 Sample 1 4.11 About 100 1 2 15 25 44 Sample 2 3.45 99.35 1 153 285 368 424 Sample 3 2.90 94.2  906 1012 1191 1245 1375 Example F TMAH Stability in Aniline, Wherein a TMAH Solid Having Varying Water Contents is Heated in Aniline [0086] This example illustrates the stability of TMAH at different water to total base (TMAH) molar ratios in the presence of aniline. [0087] TMAH samples with water to base (TMAH) molar ratios of about 4:1 and about 3:1 were prepared from and aqueous solution containing about 35% w/w of TMAH by distillation of water under reduced pressure. These samples were heated at about 80° C. in the presence of aniline for up to 2 hours in a closed system and analyzed for TMAH decomposition products, namely, trimethyl amine and N-methyl aniline. The results are summarized in Tables 7 and 8. [0000] TABLE 7 Compositions of aniline-TMAH mixtures TMAH (gm) Aniline Water:total TMAH Water:TMAH Sample (gm) molar ratio = 4.08:1 molar ratio = 3.17:1 Sample 1 3.96 1.13 — Sample 2 4.01 1.13 — Sample 3 4.20 — 1.15 Sample 4 4.07 — 1.13 [0000] TABLE 8 TMAH decomposition over time in terms of trimethylamine and N-methyl aniline formation TMAH (molar ratio with water) 4.08:1 3.17:1 Sample 1 Sample 2 Sample 3 Sample 4 Sr. Hold Hold Hold Hold No. Details (1 hr) (2 hrs) (1 hr) (2 hrs) 1 trimethylamine 1 1.47 1.65 1.79 (relative ratio)* 2 N-methyl aniline 22 40 146 359 (ppm) *= Value obtained by GC area % is taken as unity for comparison. Example 3 Coupling Reaction of Aniline with Nitrobenzene [0088] This example illustrates the effect of different molar ratios of total base (TMAH) to nitrobenzene fed to the coupling reaction on the decomposition of TMAH at the end of coupling reaction when the water to total base molar ratio is well below 0.6. [0089] The coupling reaction was carried out in a 2 liter Glass Round Bottom flask (RB flask) equipped with a stirrer (½ moon blade Teflon™ stirrer), a thermometer, a baffle, and a dropping funnel for nitrobenzene addition. Initially, an aqueous solution of TMAH (35.65% w/w, 475.16 gm, 169.39 gm on 100% basis, 1.86 moles) was charged into the RB flask. Aniline was charged (1005.4 gm, 10.81 moles) into the reactor and distillation was continued under reduced pressure at 55 mm Hg. A water and aniline mixture was removed by distillation until the molar ratio of water to TMAH was about 4:1. During this process the temperature of the reaction mass increased to 70-73° C. [0090] After attaining the required molar ratio of water to total base for the start of the coupling reaction, nitrobenzene (218.82 gm., 1.78 moles) was added continuously over a period of 180 minutes. During nitrobenzene addition, water and aniline were continuously removed from the reaction by distillation under reduced pressure at 55 mm Hg. The reaction mass was maintained at about 75° C./55 mm Hg for 0.5 hour, after completion of nitrobenzene addition (entry no. 6, Tables 9 and 10). [0091] Distillation of the aniline and water mixture was continued at about 75° C. by decreasing the pressure gradually to about 15 mm Hg so as to obtain a water to total base molar ratio below 0.6:1. The reaction mass was analyzed for nitrobenzene conversion by HPLC analysis. The reaction mass was also analyzed for TMAH content, N-methyl aniline content and moisture content by titration, HPLC and Dean Stark techniques, respectively. The results are summarized in Tables 9 and 10 (entry nos. 1 to 5). [0000] TABLE 9 Water/total Water/Free N-methyl base molar TMAH molar aniline in Free ratio - at the ratio - at the the TMAH at end of the end of the reaction the end of coupling coupling mass at the coupling reaction (NB reaction (NB end of reaction (% NB addition + addition + TMAH coupling of input) Exp. AN:NB:TMAH conversion hold) hold) Accountability reaction based on No. (molar ratio) (%) M.B. D.S. M.B. D.S. (%) (ppm) selectivity 1 6.06:1:1.21 99.83 0.49 0.57 1.94 2.26 93.94 6000 23.18 2 6.05:1:1.05 99.83 0.45 0.40 4.01 3.62 99.1 711 9.86 3 6.05:1:1.0 99.81 0.33 0.38 3.90 4.37 99.40 427 7.58 4 6.06:1:0.95 99.71 0.34 0.26 10.1 7.80 98.75 178 3.50 5 6.06:1:0.90 99.07 0.20 0.21 Practically no 99.13 56 Negligible free TMAH 6 6:1:0.90 96.08 1.29 1.33 71.4 73.89 99.16 65 1.80 M.B. = material balance; D.S. = Dean Stark method [0000] TABLE 10 Free % molar TMAH at selectivity the end of Free and bound of coupling TMAH based on azobenzene reaction input moles based on (% on input) Free NB Input Exp. AN:NB:TMAH based on TMAH Bound (HPLC) no. (molar ratio) selectivity moles TMAH Azobenzene 1 6.06:1:1.21 23.18 0.278 0.932 6.04 2 6.05:1:1.05 9.86 0.10 0.95 5.99 3 6.05:1:1.0 7.58 0.076 0.924 6.78 4 6.06:1:0.95 3.50 0.03 0.92 6.63 5 6.06:1:0.90 Negligible — about 0.90 7.26 6   6:1:0.90 1..80 0.02 0.88 6.87 Example 4 Coupling Aniline with Nitrobenzene in Continuous Manner [0092] This example illustrates the coupling reaction of aniline with nitrobenzene carried out in a continuous manner to obtain a reaction mass having a negligible presence of nitrobenzene with a water to total base molar ratio less than 0.6 and without substantial decomposition of TMAH. a) In a typical pilot plant run aniline (35.86 kg/hr), nitrobenzene (5.93 kg/hr) and TMAH (35% w/w) (11.34 kg/hr) were fed to a pre-mixer, followed by passing through a series of continuous flow reactors at about 50 mm Hg. The temperature of the reaction mass progressively increased from about 65° C. in the pre-mixer to about 80° C. with distillation of aniline and water from the flowing reaction mass. The last reactor in the series was a continuous plug flow reactor, which was maintained at 10 mm Hg and the reaction mass was passed through this continuous plug flow reactor in a continuous manner with distillation of aniline and water. The temperature of the bottom mass was about 75° C. The output was about 34 kg/hr with a negligible presence of nitrobenzene. Typical selectivity based on nitrobenzene added was about 90% for the total of 4-NODPA and 4-NDPA, azobenzene about 9.2%, and phenazine about 0.5%. The moisture content was around 0.85% w/w by the Dean-Stark method and the TMAH content by analysis around 11.6% w/w giving a water to total base molar ratio of about 0.37. The N-methyl aniline content was around 19 ppm. Thus, it was possible to reduce the water to total base molar ratio to less than 0.6 without appreciable decomposition of TMAH base. b) The reaction mass fed to the continuous plug flow reactor was separately distilled to study the effect of batch distillation on conversion and impurities formation. In a 1 liter 4-neck round bottom flask, 750 gm feed of the flow reactor mass (obtained from an intermediate step of pilot scale experiment as in a) above) was taken and heated to 75° C. under agitation. The pressure was reduced gradually to about 10 mm Hg and distillation of an aniline-water mixture was continued to complete the reaction as determined by the point when no nitrobenzene remains unreacted. The water to base molar ratio becomes less than 0.6 as a result of this distillation. At the end of distillation, typical selectivity based on nitrobenzene was 4-NODPA+4-NDPA about 89.5%, azobenzene about 9.7%, and phenazine about 0.5%. The moisture content was around 0.59% w/w by the Dean-Stark method and TMAH content was about 10.57% w/w giving a water to total base molar ratio of about 0.28. The N-methyl aniline content was around 130 ppm, indicating significantly higher TMAH decomposition in comparison to the concentration step a) carried out in a continuous plug flow reactor.

An efficient continuous manufacturing process for 4-aminodiphenylamine by coupling aniline with nitrobenzene in the presence of tetramethylammonium hydroxide (TMAH) as a base, using flow reactors wherein base decomposition is considerably reduced by optimizing base quantity, process conditions and process equipment.

BACKGROUND OF THE INVENTION This invention relates to geothermal energy in general and more particularly to an improved method of extracting geothermal energy in a hot, dry rock system. With the shortage of petroleum products and high prices, there is great deal of interest in alternate sources of energy. One such source is geothermal energy. This energy is energy taken from the natural heat of the earth. Various systems have been developed for such purposes. Typical are those disclosed in U.S. Pat. Nos. 3,817,038, 3,786,868 and 3,911,638. In a hot dry rock system such as that disclosed in U.S. Pat. No. 3,817,038, an injection well and a production well are drilled and a fluid is injected into a geothermal area through the injection well, the fluid forced through the formation with simultaneous heating and the heated fluid then recovered from the production well. The recovered heated fluid is then used on the surface to generate energy. For example, the heated fluid may be expanded to steam and used to drive a steam turbine, the condensate from the steam turbine along with any makeup water then being reinjected in the injection well to form a closed system. Another approach similar to the one in which two wells are drilled is one in which a single well is completed with a dual casing string which permits injection of cold water at the bottom of the fracture system and recovery of hot water at the top of the fracture. A third approach, which is known as "huff and puff", is one in which the well is operated in a pulsed mode where water is alternately pumped into the fracture, allowed to heat up and then withdrawn. Operation of several wells of this type in sequence provides power for sustained operation. The pulsed mode operation has the additional virtue of permitting use for load following applications, i.e., for driving a generator which follows the electrical demand load, pulsing can be controlled in dependence on the demand. Injection and production of water requires energy and any approach which diminishes the reinjection or production energy required, diminishes the cost of producing geothermal energy from this resource and increases the net amount of energy recovered from the resource reducing waste and increasing the net reserves of energy indigenous to the United States. SUMMARY OF THE INVENTION The present invention has as its object improving the efficiency of energy removal from hot rock geothermal systems. In accordance with the present invention, heat extraction from hot rock systems is accomplished in an advantageous manner by employing as a energy recovery fluid, a mixture of water and a calcium halide. In particular calcium chloride and calcium bromide may be used either separately or together. Calcium chloride has the ability to raise the specific gravity of the inflowing brine to the geothermal system to about 1.4 to 1.5 while the hot return brine will have specific gravities of only 1.0 or slightly less depending upon the termperature, pressure and content of water and any additional additives. Calcium bromide acts in similar fashion. As a result, a pressure gradient is developed which drives the circulation of the heat extracting fluid. In the pulsed mode case, the use of such a mixture serves to substantially reduce the amount of energy required to reject and recover the heat extraction fluid and as an additional benefit, reduces the energy required to fracture the hot rock, which is desirable, in that fractioning further increases heat recovery and efficiency by increasing the rock surface area available for heat transfer. The addition of a calcium halide to the energy recovery fluid of a hot dry rock geothermal energy recovery system, either the pulse or continuous injection/projection mode increases net system energy output by reducing the energy required for injecting the energy recovery fluid to the heat bearing formation due to the increased density imparted to the energy recovery fluid by the additive. Calcium halide additions further reduce the energy required for transporting the energy recovery fluid from the heat-bearing underground rock formation to the ground surface by virture of the reduced density imparted by the additive fluid while at elevated temperatures. Other materials may be added to the energy recovery fluid for other purposes. In particular materials having a high vapor pressure are helpful. An example of such a material is acetone. These materials serve to increase the hydraulic pressure of the hot fluid. In the pulse mode of heat extraction this increased pressure helps with growth of additional rock fractures that serve to provide more heat and the pressure also assists in driving the hot fluid back out of the well where it can be utilized. Acetone also reduces the ability of the mixture to dissolve minerals and diminish the suspension of colloidal solids thereby reducing the tendency of wells to scale, allowing more continuity in the recovery of energy and enhancing the economic desirability of what may have previously been considered uneconomic sources of energy. The use of acetone mixed with water for use as a fluid in such a system is described in applicant's copending Ser. No. 778,388 filed on even date herewith and entitled Improved Method for Energy Extraction From Hot Dry Rock Systems. BRIEF DESCRIPTION OF THE DRAWING The single FIGURE illustrates the type of system in which the heat extraction fluid of the present invention may be used. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, in a hot rock geothermal system, for example, a system such as that shown in the aforementioned U.S. Pat. No. 3,817,038, a mixture of water and calcium chloride and/or calcium bromide is used as the heat extraction or energy recovery fluid. Such a system is shown in basic block diagram form on the FIGURE. Shown is a closed loop system containing the heat extraction fluid of the present invention. Fluid is initially supplied to the system and made up over a line 11. The line 11 connects with a line 13 which is the input to an injection well 15. The injection well is drilled down to the depth of the hot rock system and is collected in a production well 19. The output from the production well 19, which will be the fluid heated by the hot dry rock system 17, flows in a line 21 to a steam turbine 23 where it is expanded. The turbine is used to drive a driven member 25 such as a generator. The working fluid from the steam turbine, in the form of a vapor is exhausted over a line 25 to a condenser 27 where it is brought back into the liquid state. This liquid then flows through a line 29 to a pump 31 which pumps it back into the injection well 15. As noted above, the use of a closed loop with a condenser conserves the working fluid. Whatever losses are encountered can be made up by supplying make up fluid over the line 11. Preferably, this mixture also has added to it acetone. Calcium chloride is added in an amount to raise the specific gravity of the heat extraction fluid supplied into the well, for example, in an injection well, to 1.4 to 1.5 at a temperature of approximately 20° C. After injection into the well, due to a subsequent heating which takes place in the hot rock system, the specific gravity is reduced to 1.0 or slightly less depending on the amounts of the various materials present. This then results in a pressure gradient which aids in circulation of the heat extraction fluid through the well. Acetone will normally constitute 10 to 20% by weight of the heat extraction fluid. Calcium chloride and/or calcium bromide will constitute 1 to 50% of the heat extraction fluid with the remainder water, i.e., calcium halide can be added up to its limit of solubility. The heat extraction fluid ideal high vapor pressure additive most useful in the pulse mode of heat extraction depends on the climatic conditions at the generating site. For cases such as the Imperial Valley, when 130±° F. is the normal summer cooling water temperature, then the additive should have an atmospheric pressure boiling temperature below water (212±° F) but above 130° F so that it will be condensable with a water cooling system. Acetone appears to be the superior substance for these purposes, having a boiling point of 133.7° F. If lower heat rejection temperatures are feasible, other additives are possible. In general, compounds soluble in water are superior. These include methanol, ethanol, isopropanol, acetone, and dioxane. Actually, methane, ethane, propane, butane, isobutane, and methyl ethyl ketone have sufficient water solubility at high temperatures that they serve under special conditions as usable compounds. Ammonia in water is also a useable material subject to assurance of an economically acceptable low from the heat extraction fluid loss by ion exchange with the heat source host rocks. Furthermore, additional materials can be added to the heat extraction fluid mixture forming various admixtures to accomplish secondary functions which will not depart from the scope of this invention. Includes among these are additional organic liquids to change the thermodynamic properties of the heat extraciton fluid and complexing agents to complex and extract materials of economic interest. Those skilled in the art will see many modifications and applications of the method herein described without departing from the scope of this invention. An example of a group of compounds which could have limited application are the amines. Low molecular weight amines such as tri-methyl amine could serve directly as a heat extraction medium while higher molecular weight amines either as ionized salts or as undissociated species are usable to condition the rock surfaces to change wetability; to reduce ion exchange between the heat extraction fluid and the rocks; and to serve as corrosion inhibitors for equipment installed in the well system. As a secondary function, also the solution used as a heat extraction fluid can be used to leach the hot rock of desired metals without departing from the scope of this invention. Typical complexing agents range from compounds such as acetylacetonate to complex chelating agents. Others include mild oxidants such as ferric chloride and many others. The heat of the rock provides a considerable increase in ion exchange and reaction rates compared to ordinary leaching which takes place at or near surface temperatures. The addition of the aforementioned ferric chloride or other mild oxidant can be used to liberate metal sulphides and convert the sulphur to sulphate which would be left in the hot rock as calcium sulphate while the metal chloride stays in solution. The use of calcium chloride, water, and acetone as a heat extraction fluid gives rise to a number of phenomena that may to some degree cause problems if not handled correctly and also produce certain benefits if handled properly. The presence of concentrated calcium ion solutions will induce ion exchange with framework and layer silicate minerals such as feldspars and micas respectively. This has the effect of converting calcium chloride to sodium and potassium chloride. However, the use of acetone suppresses the solubility of sodium and potassium chloride so these may tend to precipitate out on the surface of the fractures and potentially cause some blockage. Occasional flushing with acetone-free or low acetone calcium chloride will serve to dissolve these salts which can then be recovered from the wash solution. One technique known to the art of a solution mining of underground salt deposits for selective potassium chloride recovery is to cool the brine. Potassium chloride will selectively precipitate and the sodium chloride stay in solution. This can be recovered either by evaporation concentration or, if acetone is present, by addition of more acetone which will salt out the sodium chloride. Alternatively, other techniques known to the art of solution mining consist of operation in a reducing environment can permit the use of complexing agents that would be unstable in an atmospheric environment. An example of such an agent is the polysulphide ion or the bisulphide ion which acts to solubilize metal sulphide minerals. Once the minerals which are desired to be extracted are dissolved in the brine, they can be extracted using conventional techniques ranging from temperature and pressure change, pH adjustment, hydrogen reduction, ion exchange, precipitation by sulphide ions, concentration by evaporation and selected solvent extraction without departing from the scope of this invention. The wash water above as well as the normal calcium chloride brine used as a heat extraction fluid is a potential feedstock for chemicals recovery by a number of different means. The selective ion exchange of calcium for potassium and potassium recovery by cooling has been noted. The process of converting calcium chloride to potassium chloride also causes an enrichment of bromide in the calcium chloride heat extraction fluid and occasional processing through an extraction loop involving oxydation with elemental chlorine followed by absorption provides a means of bromine recovery. Lithium builds up in the calcium chloride heat extraction fluid as a consequence of ion exchange and is also a potentially valuable product which may be recovered by pH increase effected by carbonation. Silica dissolves in the heat extraction fluid at high temperatures and precipitates out at low temperatures. This provides a means of producing a high surface area amorphous, hydrated highly reactive silica usable as a feedstock for producing sodium metasilicate and related compounds as well as an absorptive carrier for other materials such as water and insecticides. This material is usable, when dry, as a filler in plastics and elastomers. This process of processing the brine by cooling so as to precipitate the silica, serves to scavenge colloidal materials such as metal sulfides. This is a direct means of recovering gold, silver, and copper. The technique involves collecting the silica precipitate either in a settling pond, baffle device, or fluidized bed followed by crushing, roasting in air to oxydize the sulfide in the precipitate followed by leaching with solubilizing chemicals. These include either alkaline cyanide solutions or dilute nitric acid solutions. As noted above, the present invention relates to a type of geothermal system which is known as a dry, hot rock system. There is another type of geothermal system known as a hydrothermal brine system. These are wet systems in which heat is recovered from hot naturally existing brine. These brines sometimes contain large amount of calcium chloride and in operating such hydrothermal wells, calcium chloride is obtained as a by-product during solar evaporation of the brines. The present invention provides a use for this by-product of hydrothermal wells, i.e., introducing the calcium chloride into a hot dry rock system to recover thermal energy therefrom, thereby enhancing the economics of hydrothermal energy reserves. In summary, the present invention in one aspect comprises mixing calcium chloride with water to form a heat extraction fluid more efficient than those presently known to the art of hot dry rock geothermal wells which will produce an increased pressure gradient and reduce the amount of energy needed to operate the well thereby improving the thermal efficiency and economic viability of the hot dry rock energy recovery systems. Furthermore, various chemical agents have been noted which are known to the art of solution mining can be added to the disclosed heat extraction mixture to perform various functions and further improve the economic efficiency of the operation without departing from the scope of this invention. Finally, the manner in which the present invention permits using a by-product of hydrothermal systems as differentiated from hot dry rock systems to reduce the cost of energy extraction from hydrothermal systems has been described.

In order to extract energy in a matter more efficient than is presently known to the art, from hot dry rock geothermal systems, a mixture of water and calcium chloride is used. The fluid mixture is injected into a formation and forced through the formation with simultaneous extraction of heat from the energy recovery or heat extraction surrounding rocks. The fluid and a larger fraction of its contained energy are then recovered than can presently be recovered by technology known to the art.

This application is a continuation-in-part of application Ser. No. 661,160, filed Oct. 15, 1984, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sealed lead-acid battery, and particularly to a sealed lead-acid battery which is sealed by utilizing what is called an "oxygen cycle," i.e., the action of causing the oxygen gas that is evolved at the positive plate toward the end of charging to react with a negative active material. 2. Description of Prior Art For a lead-acid battery to be sealed by the "oxygen cycle" the oxygen gas that is evolved toward the end of charging must be transported from the positive plates to the negative plates. In order to ensure this gas transport, a gelled electrolyte is used or absorption of the electrolyte by porous separators is adopted. Regarding the latter method, it has been recently reported that the porous separators are not completely filled with the electrolyte and voids for the transport of the oxygen gas from the positive plates to the negative plates are present in the porous separators. The idea of using these porous separators in the sealed lead-acid battery is disclosed, for example, in U.S. Pat. No. 3,862,861. It states that the sealed lead-acid battery disclosed in characterized in one aspect by the hypothesis that the porous separators have a higher capacity for absorption of electrolyte than the plates and the electrolyte within the plates is present in the form of a thin film wrapped around particles of active materials. According to this disclosure, it is inferred that the electrolyte is substantially present within the separators. With a view to improving the high rate discharge characteristics, this U.S. patent contemplates reducing the discharge current density by using thin flexible "non-self-supporting" grids. To preclude the "non-self-supporting" grids from shortening the battery service life, the plate assembly is wound under exceedingly high pressure. SUMMARY OF THE INVENTION The present inventors tried an another approach to the improvement in the high-rate discharge characteristic and service life. It has been widely known that the capacity of the sealed lead-acid battery of this type is generally affected by the concentration and amount of the electrolyte in the cell. It has been now found that the high-rate discharge characteristics is affected not only by the aforementioned concentration and amount of the electrolyte but also by its apportionment between the plates and separators of the plate assembly. For example, it has been demonstrated that, for the same concentration and the same amount of electrolyte to be added, the high-rate discharge characteristic are superior when the proportion of the electrolyte contained in the positive and negative plates is larger and the proportion in the porous separators is smaller than otherwise. This knowledge is partly described in JA-OS No. 87080/57, which was laid open for public inspection on May 31, 1982. In addition to this knowledge, it has been found that the pores of the positive and negative active material must be kept filled substantially with the electrolyte. An object of this invention is to provide a sealed lead-acid battery which has long service life and exhibits little degradation of the high-rate discharge characteristic due especially to repeated cycles of charging and discharging. Another object of this invention is to provide a sealed lead-acid battery which excels in ability to absorb O 2 gases and reproduce water during overcharging. A further object of this invention is to provide a sealed lead-acid battery which excels in ability to recover by charging after a long overdischarged-state storage. The other objects and characteristics of this invention will become apparent from the further disclosure of this invention to be made in the following detailed description of a preferred embodiment, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing changes in distribution or amounts of electrolyte absorbed by positive plates, negative plates, and separators in the sealed lead-acid battery of this invention as caused by the change in the total amount of electrolyte added to the cell. FIG. 2 is a graph showing the relation between the amount of water-loss of electrolyte and the high-rate discharge characteristic in the sealed lead-acid battery of this invention. FIG. 3 is a graph showing the alternate charge and discharge cycle life of the sealed lead-acid battery of this invention. DESCRIPTION OF PREFERRED EMBODIMENT The present invention will be described in detail below with reference to a preferred embodiment of the invention. The paste for the positive plates was obtained by mixing 100 kg of fine lead oxide powder with an average particle diameter of about 4.5 μm and a specific surface are of about 1.40 m 2 /g as measured by the BET method (hereinafter all the values of specific surface areas are invariably those measured by the same method) with 20 liters of sulfuric acid with a specific gravity of 1.14 d. Positive plates were obtained by applying the paste on cast grids of a Pb-0.09% Ca and 0.55% Sn alloy with a thickness of 3.4 mm, curing and forming thereof under ordinary conditions. The positive plates measured 76 mm in width, 82 mm in height, and 3.4 mm in thickness and contained 60 g of active material. The positive active material had a specific surface area of about 3.5 m 2 /g and an average pore diameter of about 0.32 μm. The aforementioned lead oxide powder was mixed with the ordinary expanders and other additives. The paste for the negative plates was obtained by mixing 100 kg of the lead powder mixture with 15 liters of dilute sulfuric acid with a specific gravity of 1.12 d. Negative plates were produced by applying the paste on grids with the same alloy composition as that used in the grids for the positive plates of 76 mm in width, 82 mm in height, and 1.9 mm in thickness. The pasted negative plates were also cured and formed under ordinary conditions. The amount of the negative active material thus obtained weighed about 33 g per plate. The negative active material had a specific surface area of about 0.43 m 2 /g and an average pore diameter of about 1.0 μm. A separator was prepared in the form of a sheet having a width of 83 mm and height of 88 mm, which was made by entangling together 90 wt% glass fibers having a nominal fiber diameter of about 0.8 μm with 10 wt% glass fibers having a nominal fiber diameter of about 11 μm without any binder by the wet method. This separator had a weight of 160 g/m 2 , a specific surface area of about 1.45 m 2 /g, an average pore diameter of about 7 μm, and a true specific gravity of 2.5. A cell element was assembled by alternately superimposing three positive plates and four negative plates with the separators placed between them. The cell element with a thickness of 23.5 mm was inserted in an electric cell. In this case, each distance between the plates was 0.95 mm and the pressure exerted on each assembled plate was about 15 kg/dm 2 . The total specific surface area per unit cell, therefore, was about 630 m 2 /cell for the positive active material, about 57 m 2 /cell for the negative active material, and about 10 m 2 /cell for the separators. Cell elements produced as described above were added severally in 100, 92.5, 90, 87.5, 85, 80, and 70 cc/cell of the electrolyte and then stood for 24 hours. After standing, they were lifted from the containers and examined to determine the amounts of electrolyte contained in the positive plates, negative plates, and separators. With the addition of 100 cc/cell, a certain amount of free electrolyte apparently existed in the cell. With the addition of 100 cc/cell of electrolyte, the volume of electrolyte contained per unit weight was 0.14 cc/g for the positive active material, 0.17 cc/g for the negative active material, and 7.8 cc/g for the separators. Based on these values, each taken as 100%, the changes in the volumes of the electrolyte contained in the positive plates, negative plates, and separators were evaluated. The results were as shown in FIG. 1. Though with the addition of 100 cc/cell there existed some free electrolyte, in FIG. 1, this value indicated as the point at which "the ratio of the volume of the added electrolyte to the total pore volume of the cell element" was 100%. From FIG. 1, it is noted that when the cell elements are formed of components possessing pore diameter, specific surface area, and other properties as the electrolyte was added in varying amounts to the cell element, there was a reduction in the amount of electrolyte in the separators and there was no change in either the positive active material or the negative active material. The fact indicates that when a battery is produced by assembling such components with these particular properties, the pores of the positive active material and the negative active material are always filled with the electrolyte and the separators permit presence of voids not filled with the electrolyte even when the total amount of the electrolyte is decreased by overcharging. Even if the amount of the electrolyte is decreased by overcharging, the positive plates and the negative plates are still fully filled with the electrolyte. Since the high-rate discharge characteristic is affected by the electrolyte contained in the positive plates and the negative plates, the cell element with such a characteristic is enabled to maintain the high-rate discharge characteristic at a sufficiently high level even when the electrolyte is decreased by overcharging. Besides, the separators possess the voids which are necessary for the oxygen gas evolved at the positive plates during overcharging to the transported from the positive plates to the negative plates. It is, accordingly, expected that the efficiency of the absorption of the oxygen gas reaches an exceedingly high level when the amount of the electrolyte is decreased to a certain level. Sealed lead-acid batteries were obtained by inserting the cell elements assembled as described above in a container, welding a strap, joining a lid to the container, adding dilute sulfuric acid with 1.30 specific gravity at an amount of 100 cc/cell, and fitting in a safety valve with a venting pressure of 0.2 kg/cm 2 . The sealed lead-acid batteries thus obtained exhibited a 10-hour rate discharge capacity of 11 AH, a 10C (110 A) discharged duration of 3 minute 00 second, and a 5-second voltage at discharge of 1.80 V per unit cell. These batteries were overcharged at a current of 3C (33 A) to decrease forcedly 5, 10, 15, 20, and 25 cc in the volume of electrolyte per cell, respectively. These batteries for the test were subjected to 110 A discharged at 25° C. The results were as shown in FIG. 2. It is noted from FIG. 2 that the sealed lead-acid batteries of the present invention retained the superior high-rate discharge characteristic even after the volumes of their electrolyte were decreased. FIG. 2 shows that the value of the 5-second voltage at discharge gradually decreases in accordance with the decrease of the electrolyte grows. This behavior can be explained on the basis that since the amount of the electrolyte decreased in the separators (FIG. 1), the resistance in the separators increased proportionately. Sealed lead-acid batteries which had the same construction as described above but contained 95 cc/cell of electrolyte were subjected to an alternating charging and discharging cycle-test of 4 A discharge for 2 hours and 1.7 A recharge for 6 hours. At intervals of 50 cycles, the batteries were given a high-rate discharge test at a discharge current of 110 A and a 3-hour rate discharge test. The change in the high-rate discharge characteristic along the advance of cycles is shown in FIG. 3. In the test, the efficiency of gas recombination averaged 80% during the first 50 ∞ and it was substantially 100% in the subsequent cycles, indicating no decrease in the amount of the electrolyte. This means that the sealed lead-acid battery of this invention exhibits little or no sparing decline of the high-rate discharge characteristic after repeated operation of charging and discharging cycles and possesses a long service life. The conventional sealed lead-acid battery according to the invention disclosed in U.S. Pat No. 3,862,861, for example, was assembled with the positive plates and negative plates both of an extremely thin thickness of more or less 1.0 mm and a very large plate surface area, which were enable to lower or reduce the discharge current density and to improve the high-rate discharge characteristics. During the 10C discharge of the conventional sealed lead-acid battery, the discharge current density based on one side-surface area of the positive plate is about 0.3 A/cm 2 and the discharge duration is about one minute 50 seconds to about two minutes 30 seconds. When the sealed lead-acid battery of this invention is tested under the same conditions, the discharge duration is about three minutes in spite of the condition that the discharge current density based on one side surface area of the positive plate is about 0.6 A/cm 2 , which is twice larger that of the conventional sealed lead-acid battery. To obtain a superior high-rate discharge characteristic without sacrificing the other characteristics, the optimum thickness of the grids for the positive plates is from 3 to 4 mm. By fixing the proper thickness of the grids within that range, the proper thickness of the separators is able to be used calculated eventually. Moreover, this invention permits the sealed lead-acid battery to maintain the high-rate discharge characteristics during its long service life. Further, even at a lower stacking pressure the sealed lead-acid battery of this invention can be expected to have a longer service life than the sealed lead-acid battery conforming to the invention of U.S. Pat. No. 3,862,861 because the grids of this invention are about three times thicker than that of the battery of the noted U.S. patent. A sealed lead-acid battery of this invention can be obtained by selecting appropriately the positive plates, negative plates and the separators with a certain suitable range of pore diameter, specific surface area and other properties so as to become to the construction within the size of plate which comprises a larger amount of electrolyte contained in the positive and negative active materials than that in the separators and so as to be no decrease in the amount of electrolyte in the positive and negative active materials in spite of the condition that the total volume of electrolyte in the cell is reduced due to overcharging. That is in the case of the preferred embodiment described above, by evaluating the distribution of the electrolyte content of the cell element within the plate size, the positive plates contain about 25 cc/cell, negative plates contain about 23 cc/cell, and the separators contain about 34 cc/cell, representing the content ratios of about 30.5% for the positive plates, about 28.0% for the negative plates, and about 41.5% for the separators and indicating that the sum of the electrolyte contained in the positive plates and the negative plates is about 60% of the whole electrolyte so contained. Moreover, the electrolyte contained in the positive and negative plates remains intact and that contained in the separators alone is lost when the whole amount of the electrolyte is decreased due to the water electrolysis during overcharging, therefor the ratio sum of the electrolyte contained in the positive plates and the negative plates to the whole amount of the electrolyte in the cell gradually increased from the aforementioned value of 60%. Thus, the high-rate discharge characteristic cannot be impaired. As mentioned above, in order to establish the condition that only the electrolyte in the separators decreases and the electrolyte in the positive plates and the negative plates always remains filling them when the total amount of the electrolyte is decreased, the separators for use in the battery must be selected so that the electrolyte absorption and retention power of capability of separators will be lower than that of the positive active material and the negative active material. Although it is not clarified completely what properties determine the electrolyte absorption and retention power or capability of each of the component elements of the cell element, it may be safely inferred that the electrolyte absorption power and the elecrtrolyte retention capability are affected by the wettability of the each component with the electrolyte, the specific surface area of each component per unit volume, the pore diameter distribution, and so on. When the foregoing preferred embodiment is reviewed in terms of specific surface area (Sv) per unit volume on the basis that the positive plates, negative plates, and separators have 8, 11, and 2.5 g/cc as their respective values of true specific gravity, the values of Sv is found to be about 28, about 4.73, and about 3.6 m 2 /cc., respectively. Thus, the separators are shown to have the smallest value of Sv. The separators marketed under trademark designation Dexter #225B (product of The Dexter Corp., USA) are of the separators usable for batteries of this kind. The separators of Dexter #225B have a specific surface area of about 2.5 m 2 /g, which is greater than that of the separators involved in the preferred embodiment by this invention, 1.45 m 2 /g and which is corresponding to be Sv of 6.25 m 2 /cc on the basis of its true specific gravity of 2.5 g/cc, which is a value larger than that of the negative active material. If the separators of Dexter #225B are used in the sealed lead-acid battery by this invention, there is a possibility that the pores in the positive plates and the negative plates will not be substantially filled with the electrolyte when the total amount of the electrolyte is decreased. Further, because separators of Dexter #225B have an average pore diameter of about 3 μm, which is a value smaller than the value about 7 μm shown by the separators of the preferred embodiment, and eventually the electrolyte absorption and retention power of separators is stronger, there remains the above-mentioned anxiety. When separators having such a high Sv value as Dexter 225B are effectively used in the sealed lead-acid battery by the present invention, the plates, particularly the negative plates are required to have a larger specific surface area. The plates, therefore, are required to be made of lead oxide powder with much smaller particle diameter than above or most be made of a material incorporating therein various additives which are capable of notably increasing the specific surface area of the plates. The characteristics disclosed by this invention that the electrolyte should substantially fill the pores of the plates and that there exist unfilled voids in part of the pores of the separators is fulfilled by using separators which have a smaller, preferably slightly smaller electrolyte absorption and retention power or capability than the plates. Such types of separators are also usable in sealed lead-acid batteries which require no or inferior high-rate discharge characteristics, namely such as the sealed lead-acid batteries for emergency power sources in which the distance between each plates is from about 1 to 2.5 mm. This kind of sealed lead-acid battery is also embraced by the present invention. What is important is that the separators to be adopted should possess a smaller electrolyte absorption and retention power or capability than the plates. Although the inventors have not yet found the characteristic properties completely which permits suitable expression of the electrolyte absorption and retention power and capability, when the cell element is assembled as specifically discussed in the preferred embodiment, the electrolyte is distributed so that the pores in the active materials of the plates remain fully filled with the electrolyte and the pores in the separators permit partial existence of voids when the total volume of the electrolyte is decreased. By using the cell element with the construction as described above, there can be obtained a sealed lead-acid battery which enables to maintain not only the superior low rate discharge characteristic but also the initial-stage high-rate discharge characteristic for a long time during the service life of the battery even when the total amount of the electrolyte is decreased. The initial-stage high-rate discharge characteristic itself is controlled preponderantly by the distances between the positive plates and the negative plates, and the amount of electrolyte in positive active material and the negative active material, particularly the amount of sulfuric acid contained in the positive active material. For example, when the battery is so produced that the distances between each plate have a thickness of 2.0 mm and the sum of the amount of the electrolyte contained in the positive active material and the negative active material is 40% of the total electrolyte (then the content in the separators is 60%), high-rate discharge characteristic is not very satisfactory. If the separators of the battery have a higher capacity for absorption and retention of the electrolyte than the plates, the high-rate discharge characteristic of the battery may be further degraded because the amount of the electrolyte in the plates gradually decreases as the total electrolyte of the battery decreases owing to the water electrolysis. When the separators assembled in the cell element have a smaller electrolyte absorption and retention power or capability than the plates as disclosed by this invention, the produced battery is characterized by the matter that the initial-stage high-rate discharge characteristic can be retained intact in spite of the decrease of the total amount of the electrolyte due to water electrolysis. It can be easily explained that since the time required for diffusion of the oxygen gas through the separator increases in proportion as the distances between the positive plate and negative plate are widened in thickness, the efficiency of gas recombination tends to degrade in proportion at the distances between the plates are widened. In the sealed lead-acid battery by this invention, bacause the voids become to be formed in the separators in consequence of the decrease of the electrolyte due to water electrolysis such a situation permits easy transport of the oxygen gas from the positive plates to the negative plates, and thus, the efficiency of gas recombination is amply high even when the distances between the plates are widened. The sealed lead-acid battery of this invention, when intended for an application necessitating the superior high-rate discharge characteristic, is disclosed by using separators with a thinner thickness than the plates, particularly the positive plates. To prevent short-circuiting and to ensure satisfactory high-rate discharge characteristic, the thickness of the separators is desired to be in the range of 0.4 to 0.25 times the thickness of the positive plates. The distance between the positive plates and the negative plates is 0.7 to 1.0 mm when the thickness of the positive plates is 3 to 4 mm. In the preferred embodiment described above, for example, the separators used therein had a thickness of about one third of the thickness of positive plates. The reason for such a range is that the high-rate discharge characteristic is degraded if the thickness exceeds 0.4 times and the possibility of short-circuiting arises if the thickness is less than 0.25 times. With respect to theoretical capacity, in the sealed lead-acid battery of this type, the total amount of the positive active material and the negative active material is greater than that of the electrolyte. That is, the capacity of the sealed lead-acid battery is affected by the amount of the electrolyte (namely the amount of sulfuric acid) and, even toward the end of discharge, the active materials still retain some undischarged portion. Such a condition applies to the sealed lead-acid battery of this invention. In the overdischarged condition, the electrolyte becomes nearly water. Particularly in the battery of the present invention, this phenomenon is outstandingly conspicuous because the sum of the amount of the electrolyte contained in the positive plates and the negative plates is about 60% or more for the total electrolyte. When the battery is left standing long at the overdischarged state, lead is dissolved. Because the dissolved lead ions is precipitated to be metal in the separators during the next recovery charging, there is a high possibility of causing short-circuit between the positive plates and the negative plates. When the battery is designed specifically to be used for high-rate discharge, the possibility of short-circuit is more outstanding because the thickness of separators is thinner than that of plates. To reduce the concentration of the dissolved lead, therefore, it is desirable to add to the electrolyte such an alkali metal salt as Na, K, or Li salt as an impurity matter. Although such an addition of an impurity matter constitutes itself a known technique to the art, in the case of the sealed lead-acid battery of this invention, the amount of impurity matters must be greater than the normally accepted levels or ranges because the sum of the amount of the electrolyte contained in the positive active material and the negative active material is greater than the amount of the electrolyte contained in the separators and because the thickness of the separators is thinner than that of the plates. To determine the optimum amount of the addition of the alkali metal salts, the following experiments were carried out. Experiments: Batteries were produced with the same construction as used in the aforementioned tests for service life through alternating charging and discharging cycle. Electrolytes were prepared by adding 0.1, 0.5, 1.0, 1.5, 2.0, 5.0 and 10.0%, respectively, of K 2 SO 4 to dilute sulfuric acid solution with 1.30 specific gravity. The electrolytes were severally added to each battery same in a volume of 90 cc per cell. These batteries were discharged to 0 V and then left standing at the outer short-circuit state at room temperature for two weeks. Then these batteries were checked whether there occurred the short-circuiting and determined whether or not they could be recharged. The results were as shown in Table 1 below. It is noted from Table 1 that the amount of K 2 SO 4 added is desired to be more than at least 1.0%. Although this experiment offered insufficient definite data for the upper limit to the amount of the alkali metal salt, it is practically desirable to fix the upper limit at 5.0% in taking into consideration of self discharge and operation of dissolving. TABLE 1______________________________________Amount of K.sub.2 SO.sub.4 added (%) Occurrence of short-circuit______________________________________0.1 Yes0.5 Yes1.0 No1.5 No2.0 No5.0 No10.0 No______________________________________ In the case of the sealed lead-acid battery by the present invention, in order to improve the high-rate discharge characteristics particularly at low temperatures, the amount of the positive active material is desired to be larger than that of the negative active material. It is well known that in the conventional lead-acid battery with the free electrolyte the high-rate discharge characteristic at low temperature is controlled mainly by the negative plates. In the case of the sealed lead-acid battery by this invention, the high-rate discharge characteristic at low temperature is controlled not by the negative plates but by the amount of sulfuric acid present in the positive active material. It is, therefore, desirable for the pore volume contained in the positive active material to be equal to or greater than that in the negative active material. When the specific pore volume (Vsp) of the positive active material is evaluated to be 0.14 cc/g and that (V SN ) of the negative active material at 0.17 cc/g, for example, since the ratio of V SN /V sp is 1.21, the amount of the active material for the positive plates is desired to be 1.21 times or more than the amount for the negative plates, although the amount of the pores in positive plate is variable with the amount of sulfuric acid used in mixing the finely divided lead oxide powder. In terms of theoretical capacity of active materials, therefore, the positive plates are desired to be larger in the capacity than the negative plates in the sealed lead-acid battery by the present invention. In evaluating the ratio of the positive active material and the negative active material to the theoretical capacity 1÷3.867=0.259 for the negative plates and 1.21÷4.463=0.271 for the positive plates and, therefore, the ratio of the theoretical capacity of the negative plates to that of the positive plates is desired to be less than 0.954 because 0.259÷0.271=0.954. It is clear from the data given in the preferred embodiment that such a this relationship has no adverse effect upon the "oxygen cycle." As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The invention involves a sealed lead-acid battery comprising a cell element having positive plates, negative plates and separators, and electrolyte retained within micropore of the cell element. The micropores of both the plates is substantially filled with the electrolyte, while the micropores of the separators are not completely filled with the electrolyte. The voids formed partially in the micropores of the separators permit transport of the oxygen gas from the positive plates to the negative plates. Such a sealed lead-acid battery has long service life, and excels in ability to O 2 absorb gases and reproduce water during overcharging and to recover by charging after a long overdischarged-state storage.

BACKGROUND OF THE INVENTION This invention is generally in the area of drug delivery systems, especially in the area of oral, rectal, vaginal and nasal drug delivery. Drug delivery takes a variety of forms, depending on the agent to be delivered and the administration route. A preferred mode of administration is non-invasive; i.e., administration via nasal or oral passages. Some compounds are not suited for such administration, however, since they are degraded by conditions in the gastrointestinal tract or do not penetrate well into the blood stream. Controlled release systems for drug delivery are often designed to administer drugs in specific areas of the body. In the gastrointestinal tract it is critical that the drug not be entrained beyond the desired site of action and eliminated before it has had a chance to exert a topical effect or to pass into the bloodstream. If a drug delivery system can be made to adhere to the lining of the appropriate viscus, its contents will be delivered to the targeted tissue as a function of proximity and duration of the contact. There are two major aspects to the development of an adhesive bond between a polymer and the gastrointestinal tissue: (i) the surface characteristics of the bioadhesive material, and (ii) the nature of the biological material with which the polymer comes in contact. The intestinal mucosa is formed of a continuous sheet of epithelial cells of absorptive and mucin-recruiting cells. Overlying the mucosa is a discontinuous protective coating, the mucus, which is made of more than 95% water, as well as electrolytes, proteins, lipids and glycoproteins—the latter being responsible for the gel-like characteristics of the mucus. These glycoproteins consist of a protein core with covalently attached carbohydrate chains terminating in either sialic acid or L-fucose groups. The carbohydrate structure of the intestinal mucous glycoproteins is similar to that of the glycoproteins which are part of the epithelial cell membrane. The mucous glycoproteins act as “dummy receptors” for carbohydrate binding ligands which have evolved in nature to allow microorganisms and parasites to establish themselves on the gut wall. One function of the mucus is to intercept these ligands and associated infective agents and thereby protect the mucosa. An orally ingested product can adhere to either the epithelial surface or the mucus. For the delivery of bioactive substances, it would be advantageous to have a polymeric device adhere to the epithelium rather than the mucous layer. For some types of imaging purposes, adhesion to both the epithelium and mucus is desirable whereas in pathological states, such as in the case of gastric ulcers or ulcerative colitis, adhesion to cells below the mucosa may be unavoidable. Bioadhesion in the gastrointestinal tract proceeds in two stages: (1) viscoelastic deformation at the point of contact of the synthetic material into the mucus substrate, and (2) formation of bonds between the adhesive synthetic material and the mucus or the epithelial cells. Several microsphere formulations have been proposed as a means for oral drug delivery. These formulations generally serve to protect the encapsulated compound and to deliver the compound into the blood stream. Enteric coated formulations have been widely used for many years to protect drugs administered orally, as well as to delay release. Other formulations designed to deliver compounds into the blood stream, as well as to protect the encapsulated drug, are formed of a hydrophobic protein, such as zein, as described in PCT/US90/06430 and PCT/US90/06433; “proteinoids”, as described in U.S. Pat. No. 4,976,968 to Steiner; or synthetic polymers, as described in European Patent application 0 333 523 by The UAB Research Foundation and Southern Research Institute. EPA 0 333 523 describes microparticles of less than ten microns in diameter that contain antigens, for use in oral administration of vaccines. The microparticles are formed of polymers such as poly(lactide-co-glycolide), poly(glycolide), polyorthoesters, poly(esteramides), polyhydroxybutyric acid and polyanhydrides, and are absorbed through the Peyer's Patches in the intestine. It would be advantageous if there was a method or means for increasing the absorption of these particles through the mucosal lining, or for delaying still further transit of the particles through the nasal or gastrointestinal passages. Duchene, et al., Drug Dev. Ind. Pharm. 14(2&3), 283-318 (1988), reviews the pharmaceutical and medical aspects of bioadhesive systems for drug delivery. “Bioadhesion” is defined as the ability of a material to adhere to a biological tissue for an extended period of time. Bioadhesion is clearly one solution to the problem of inadequate residence time resulting from the stomach emptying and intestinal peristalsis, and from displacement by ciliary movement. For bioadhesion to occur, an intimate contact must exist between the bioadhesive and the receptor tissue, the bioadhesive must penetrate into the crevice of the tissue surface and/or mucus, and chemical bonds must form. Bioadhesive power of the polymers is affected by both the nature of the polymer and by the nature of the surrounding media. Duchene, et al., tested polymers for bioadhesion by measuring the surface tension between a plate containing a mucous sample and a polymer coated glass plate. They review other systems using intestinal membrane rather than a mucosal solution, and in vivo studies using rats and radiolabeled polymeric material in a gelatin capsule. A number of polymers were characterized as to their bioadhesive properties but primarily in terms of “excellent” or “poor”. Polycarbophils and acrylic acid polymers were noted as having the best adhesive properties, although the highest adhesive forces were still less than 10 mN/cm 2 . Others have explored the use of bioadhesive polymers. Smart, et al., J. Pharm. Pharmacol . 36:295-299 (1984), reported on a method to test adhesion to mucosa using a polymer coated glass plate contacting a dish of mucosa. A variety of polymeric materials were tested, including sodium alginate, sodium carboxymethylcellulose, gelatin, pectin, and polyvinylpyrrolidone. Gurney, et al., Biomaterials 5, 336-340 (1984), concluded that adhesion may be effected by physical or mechanical bonds; secondary chemical bonds; and/or primary, ionic or covalent bonds. Park, et al., Alternative Approaches to Oral Controlled Drug Delivery: Bioadhesives and In - Situ Systems 163-183 J. M. Anderson and S. W. Kim, ed., Recent Advances in Drug Delivery (Plenum Press N.Y. 1984), report on the use of fluorescent probes in cells to determine adhesiveness of polymers to mucin/epithelial surfaces. Their results indicated that anionic polymers with high charge density appear to be preferred as adhesive polymers. None of these studies involved the study of tensile measurement between microspheres and intestinal tissue. Microspheres will be affected by other factors, such as the mucosal flow, peristaltic motion, high surface area to volume ratio. Mikos, et al., in J. Colloid Interface Sci . 143, 2:366-373 (May 1991) and Lehr, et al., J. Controlled Rel. Soc . 13:51-62 (1990), both disclose the bioadhesive properties of polymers used for drug delivery: polyanhydrides and polyacrylic acid, respectively. Mikos, et al., report that the bioadhesive forces are a function of surface area, and are significant only for particles in excess of 900 microns in diameter (having an adhesive force of 120 μN, equivalent to 10.9 mN/cm 2 ), when measured in vitro. However, they also note that this may not be an adequate adhesive force in vivo, since the larger particle size is also subjected to greater flow conditions along the mucosa which may serve to displace these larger particles. In addition, Mikos, et al., found very small forces for particles smaller than 750 μ. Lehr, et al., screened two commercially available microparticles of a diameter in excess of 500 microns formed of copolymers of acrylic acid, using an in vitro system, and determined that one copolymer “polycarbophil” increased adhesion over a control but that the other polymer did not. Polymeric coatings were also applied to polyhydroxyethylmethacrylic acid and tested in an in vivo model. As shown in Table 1, the maximum adhesive force was approximately 9 mN/cm 2 for polycarbophil. Most prior art techniques for measuring in vitro bioadhesion are based on tensile experiments. These techniques were mainly designed for large tablets or polymer coated onto glass plates. Only a few in vitro techniques for direct measurement of adhesion forces between individual microcapsules and intestinal tissue are known. Some publications used a flow channel method. However, the only reported results are static measurements where the mucoadhesive force exerted on each particle was determined by placing small particles over intestinal mucosa and measuring the immersed surface area and the directional contact angles using video microscopy, by Mikos, et al. It is therefore an object of the present invention to provide bioadhesive polymeric microspheres that are useful for drug delivery via the mucosal membranes. It is a further object of the present invention to provide polymeric microspheres which can be used for imaging studies. It is another object of the present invention to provide a method for determining bioadhesiveness of polymeric microspheres. SUMMARY OF THE INVENTION Bioadhesive polymers in the form of, or as a coating on, microcapsules containing drugs or bioactive substances which may serve for therapeutic, diagnostic, or diagnostic purposes in diseases of the gastrointestinal tract, are described. The polymeric microspheres all have a bioadhesive force of at least 11 mN/cm 2 (110 N/CM 2 ). Techniques for the fabrication of bioadhesive microspheres, as well as a method for measuring bioadhesive forces between microspheres and selected segments of the gastrointestinal tract in vitro are also described. This quantitative method provides a means to establish a correlation between the chemical nature, the surface morphology and the dimensions of drug-loaded microspheres on one hand and bioadhesive forces on the other, allowing the screening of the most promising materials from a relatively large group of natural and synthetic polymers which, from theoretical consideration, should be used for making bioadhesive microspheres. These methods and materials are particularly useful for the oral administration of a wide range of drugs, particularly sulfonamides (e.g., sulfasalazine) and glycocorticoids (e.g., betamethasone), all of which are being used for treatment of bowel diseases. Bioadhesive microspheres containing barium sulphate for use in imaging have the following advantages over conventional administration of barium: (1) produce more uniform coverage as well as better adhesion of the barium to the mucosa in the stomach and the intestine, (2) eliminate the problem of barium sulphate precipitation by protecting it from the local pH. Encapsulation of radio-opaque materials and drugs in the same type of polymer but in different microcapsules and simultaneous administration of both type of microcapsules could provide a useful tool for studying the exact location of the delivery system in the GI tract. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tissue chamber used to measure bioadhesive forces of polymeric microspheres. FIG. 2 is a graph of force (mg) versus stage position (mm) for a typical P(CPP:SA) microsphere. FIG. 3 a is a graph of force of detachment per projected surface area (mN/cm 2 ) for various polymers. The polymers used in this study included the following: alginate (one sample prepared several hours prior to testing (alginate (f)) [diam.=700μ] and another prepared several months prior to testing and left in a Ca + solution (alginate (o)) [diam.=2400μ]), alginate/polyethylene imide (alginate/PEI) [diam.=2100μ], carboxymethylcellulose (CMC) [diam.=1800μ], chitosan (high molecular weight) [diam.=2000μ], polyacrylonitrile/polyvinyl chloride (PAN/PVC) [diam.=2900μ], polylactic acid: MW=2,000 (one sample made by the hot melt technique (PLA 2K HM) [diam. =780μ] and one sample made by the solvent evaporation technique (PLA 2K SE) [diam.=800μ]), polystyrene [diam.=800μ], poly[bis(p-carboxy phenoxy) propane-co-sebacic anhydride] made with sudan red dye (P(CPP:SA)) [diam.=780μ], and poly[fumaricco-sebacic anhydride] (one sample made with acid orange dye (P(FA:SA)A) [diam.=780μ] and one sample containing no dye (P(FA:SA) B [diam.=780μ]). The forces were measured as the weight (mg) required to remove the microsphere from the intestinal tissue after a seven minute adhesion time using the Cahn electrobalance and converted to units of force (mN). These forces were then normalized by dividing by the surface area in contact with the tissue for each case. The surface areas were determined by the projection of the spherical cap of the microsphere that penetrated below the surface level of the tissue (Area=πR 2 −π(R−a) 2 , where ‘R’ is the microsphere radius and ‘a’ is the depth of penetration). All force/surface area values are presented with the standard errors of measure (SEM). FIG. 3 b is a graph of the work of detachment (nJ) for the polymeric microspheres described in FIG. 3 a . Work values were determined from the areas beneath the curves of the force versus distance graphs produced with the Cahn electrobalance, and are presented with standard errors of measure. FIG. 3 c is a graph of work of detachment per projected surface area (pJ/cm 2 ) for the polymeric microspheres described in FIG. 3 a . All work/surface area values are presented with the standard errors of measure. FIG. 4 a is a graph of the weight of detachment versus Microsphere Diameter. The microspheres in this study were poly[bis(p-carboxy phenoxy) propane-co-sebacic anhydride] made with sudan red dye made by the hot melt technique. The microsphere diameters were measured with a micrometer prior to testing. The weight of detachment is the weight, measured by the Cahn electrobalance, which is required to remove the microsphere from the intestinal tissue after a seven minute adhesion time. FIG. 4 b is a graph of the force of detachment/surface area (mN/cm 2 ) versus microsphere diameter (microns) for p(CPP:SA) microspheres. FIG. 5 a is a graph of the weight of detachment (mg) versus microsphere diameter (microns) for poly[fumaric-co-sebacic anhydride] (p(FA:SA)) made by the hot melt technique. The microsphere diameters were measured with a micrometer prior to testing. The weight of detachment is the weight, measured by the Cahn electrobalance, which is required to remove the microsphere from the intestinal tissue after a seven minute adhesion time. FIG. 5 b is a graph for force of detachment per projected surface area versus microsphere diameter for P(FA:SA) microspheres. In this figure, the values from FIG. 3 c have been normalized by the projected surface areas as described in FIG. 3 a. FIG. 6 is a X-ray print of rats fed with barium sulphate loaded P(CPP:SA) microspheres. FIG. 7 is a graph of intestinal and stomach transit time (hours) for barium, polystyrene and P(CPP:SA) as a function of bead size (microns). FIG. 8 a is a SEM of microsphere adhering to the mucosa. FIG. 8 b is a photograph of a p(FA:SA) microsphere in the device of FIG. 1 being detached from porcine jejunum using the Cahn electrobalance. DETAILED DESCRIPTION OF THE INVENTION In general terms, adhesion of polymers to tissues may be achieved by (i) physical or mechanical bonds, (ii) primary or covalent chemical bonds, and/or (iii) secondary chemical bonds (i.e., ionic). Physical or mechanical bonds can result from deposition and inclusion of the adhesive material in the crevices of the mucus or the folds of the mucosa. Secondary chemical bonds, contributing to bioadhesive properties, consist of dispersive interactions (i.e., Van der Waals interactions) and stronger specific interactions, which include hydrogen bonds. The hydrophilic functional groups responsible for forming hydrogen bonds are the hydroxyl (—OH) and the carboxylic groups (—COOH). Adhesive microspheres have been selected on the basis of the physical and chemical bonds formed as a function of chemical composition and physical characteristics, such as surface area, as described in detail below. These microspheres are characterized by adhesive forces to mucosa of greater than 11 mN/cm 2 . Classes of Polymers Useful in Forming Bioadhesive Microspheres. Suitable polymers that can be used to form bioadhesive microspheres include soluble and insoluble, nonbiodegradable and biodegradable polymers. These can be hydrogels or thermoplastics, homopolymers, copolymers or blends, natural or synthetic. A key feature, however, is that the polymer must have a bioadhesive force of between 110 N/m 2 (11 mN/cm 2 ) and 5000 N/m 2 to a mucosal membrane of a patient. Two classes of polymers appear to have potentially useful bioadhesive properties: hydrophilic polymers and hydrogels. In the large class of hydrophilic polymers, those containing carboxylic groups (e.g., poly[acrylic acid]) exhibit the best bioadhesive properties. One could infer that polymers with the highest concentrations of carboxylic groups should be the materials of choice for bioadhesion on soft tissues. Other promising polymers were: sodium alginate, carboxymethylcellulose, hydroxymethylcellulose and methylcellulose. Some of these materials are water-soluble, while others are hydrogels. Hydrogels have often been used for bioadhesive drug delivery; however, one big drawback of using hydrogels is the lack of long-term stability during storage which is a problem for therapeutic applications. Rapidly bioerodible polymers such as poly[lactide-co-glycolide], polyanhydrides, polyorthoesters—which would expose carboxylic groups on the external surface as their smooth surface erodes—are excellent candidates for bioadhesive drug delivery systems in the gastrointestinal tract. Biodegradable polymers are more stable than hydrogels. In addition, polymers containing labile bonds, such as polyanhydrides and polyesters, are well known for their hydrolytic reactivity. Their hydrolytic degradation rates can generally be altered by simple changes in the polymer backbone. Representative natural polymers are proteins, such as zein, serum albumin, or collagen, and polysaccharides, such as cellulose, dextrans, and alginic acid. Representative synthetic polymers include polyamides, polycarbonates, polyalkylenes, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyvinyl alcohols, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone, polyglycolides, polysiloxanes, polyurethanes, alkyl cellulose, hydroxyalkyl celluloses, cellulose ethers, cellulose esters, nitrocelluloses, polymers of acrylic and methacrylic esters, poly[lactide-co-glycolide], polyanhydrides, polyorthoester blends and copolymers thereof. Specific examples of these polymers include cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxymethyl cellulose, cellulose triacetate, cellulose sulphate, poly(methyl methacrylate), poly(ethyl methacylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate), poly(octadecyl acrylate), polyethylene, polypropylene, poly(ethylene glycol), poly(ethylene oxide), poly(ethylene terephthalate), poly(vinyl alcohols), poly(vinyl acetate), poly(vinyl chloride), polystyrene and polyvinylpyrrolidone, polyurethane, polylactides, poly(butyric acid), poly(valeric acid), poly[lactide-co-glycolide], polyanhydrides, polyorthoesters, poly(fumaric acid), and poly(maleic acid). These polymers can be obtained from sources such as Sigma Chemical Co., St. Louis, Mo., Polysciences, Warrenton, Pa., Aldrich, Milwaukee, Wis., Fluka, Ronkonkoma, N.Y., and BioRad, Richmond, Calif. In the studies detailed below, a variety of polymer microspheres were compared for adhesive force to mucosa. Negatively charged hydrogels, such as alginate and carboxymethylcellulose, that expose carboxylic groups on the surface, were selected, as well as some positively-charged hydrogels, such as chitosan. The rationale behind this choice is the fact that most cell membranes are actually negatively charged and there is still no definite conclusion as to what the most important property is in obtaining good bioadhesion to the wall of the gastrointestinal tract. Thermoplastic polymers: (a) non-erodible, neutral polystyrene, and (b) semicrystalline bioerodible polymers that generate carboxylic groups as they degrade—polylactides and polyanhydrides, were also selected. Polyanhydrides are good candidates for bioadhesive delivery systems since, as hydrolysis proceeds, more and more carboxylic groups are exposed to the external surface. Polylactides erode by bulk erosion; furthermore, the erosion is slower. In designing these systems as bioadhesive polymers, polymers that have high concentrations of carboxylic acid were preferred. This was done by using low molecular weight polymers (Mw 2000), since low molecular weight polymer contain high concentration of carboxylic acids at the end groups. Measurement of Bioadhesive Studies Using a Tensile Technique The adhesive forces between polymer microspheres and segments of intestinal rat tissue can be measured using the Cahn DCA-322, as shown in FIG. 1 . Although this piece of equipment is designed for measuring contact angles and surface tensions using the Wilhelmy plate technique, it is also an extremely accurate microbalance. The DCA-322 system includes a microbalance stand assembly, a Cahn DACS computer, and an Okidata Microline 320 dot matrix printer. The microbalance unit consists of stationary sample and tare loops and a moving stage powered by a stepper motor. The balance can be operated with samples weighing up to 3.0 g, and has a sensitivity rated at 0.001 dynes. The stage speed can be adjusted from 20 to 264 μm/sec using the factory installed motor, or from 2-24 μm/sec using the optional slow motor. Adhesive forces were measured by attaching a polymer sample to one of the sample loops and placing an adhesive substrate 10, intestinal tissue, below it on the moving stage 20. For adhesive measurements, 1.5 cm sections are cut from the excised intestine. These were then sliced lengthwise and spread flat, exposing the lumen side. The samples were then placed in a temperature-regulated chamber 30 , clamped 32 at their edges, and covered with approximately 0.9 cm high level of phosphate buffer saline, as shown in FIG. 1 . Physiologic conditions were maintained in the chamber. The chamber was then placed in the microbalance enclosure and a microsphere, mounted on a wire and hung from the sample loop of the microbalance, was brought in contact with the tissue. The microspheres were left in contact with the tissue for seven minutes with an applied force of approximately 0.25 mN and then pulled vertically away from the tissue sample while recording the required force for detachment. The contact area was estimated to be the surface area of the spherical cap defined by the depth of penetration of the bead below the surface level of the tissue. The force values were normalized by the projected area of this cap (Area=πR 2 −π(R−a) 2 , where R is the microsphere radius and a is the depth of penetration. For microspheres larger than 800 μm, a=400 m was used, for smaller microspheres a=R was used. Graphs of force versus distance as well as force versus time were studied. FIG. 2 shows a typical graph of force versus stage position for the P(CPP-SA) 20:80 microspheres. Point A in FIG. 2 indicates the applied force, which can be varied in each experiment, and which indirectly affects the degree of penetration into the tissue. Portion AB indicates the adhesion time, the time the sphere is left to interact with the tissue before movement of the stage is started to separate the surfaces. Segment BC indicates the elevation of the sphere to 0 mg applied force (point C). During the early part of the tensile experiment (CD), the force increases as a function of stage position, while the contact area between the sphere and the mucus is assumed to be constant and equal to the surface of the immersed sphere. The next portion of this curve (DE) indicates a period where partial detachment of the polymeric device from the mucus occurred with some changes in the contact area. The last point (E) is the detachment of the sphere from the mucus. In some cases, a detachment does not occur until the microsphere has been moved to a height of 4 mm above the initial level of contact. From these graphs it is possible to determine the maximum force applied to the sample, the maximum adhesive force, the distance required for detachment of the samples and the work of adhesion (the surface under the force versus stage position curves CDE). More importantly, it allows quantification of the adhesive forces of a variety of individual microspheres and correlation of these forces with physical and chemical properties of the polymers. Modification of Bioadhesive Polymers to Increase Bioadhesive Force. The polymers are selected from commercially available polymers based on their adhesive properties using the method described above to determine those polymers forming microspheres (either as solid polymer or as a polymeric coating on a different material) having an adhesive force greater than 11 nN/mg 2 . The microspheres are then formed having an appropriate surface area to provide the desired adhesive forces. The polymers (or polymeric surface) can also be modified as described below to increase the bioadhesive properties of the polymer. For example, the polymers can be modified by increasing the number of carboxylic groups accessible during biodegradation, or on the polymer surface. The polymers can also be modified by binding amino groups to the polymer. The attachment of polyethyleneimine or polylysine-coated acrylamide beads to intestine is probably due to the electrostatic attraction of the cationic groups coating the beads to the net negative charge of the mucus. The mucopolysaccharides and mucoproteins of the mucin layer, especially the sialic acid residues, are responsible for the negative charge coating. Any ligand with a high binding affinity for mucin could also be covalently linked to most microspheres with the appropriate chemistry, such as CDI, and be expected to influence the binding of microspheres to the gut. The ligand affinity need not be based only on electrostatic charge, but other useful physical parameters such as solubility in mucin or else specific affinity to carbohydrate groups. The covalent attachment of any of the natural components of mucin in either pure or partially purified form to the microspheres would decrease the surface tension of the bead-gut interface and increase the solubility of the bead in the mucin layer. The list of useful ligands would include but not be limited to the following: sialic acid, neuraminic acid, n-acetyl-neuraminic acid, n-glycolylneuraminic acid, 4-acetyl-n-acetylneuraminic acid, diacetyl-n-acetylneuraminic acid, glucuronic acid, iduronic acid, galactose, glucose, mannose, fucose, or else any of the partially purified fractions prepared by chemical treatment of naturally occurring mucin, e.g., mucoproteins, mucopolysaccharides and mucopolysaccharide-protein complexes. The covalent attachment of lectins to microspheres would also increase the affinity of the spheres to components of the mucin and mucosal cell layer. Useful lectin ligands include lectins isolated from: Abrus precatroius, Agaricus bisporus, Anguilla anguilla, Arachis hypogaea, Pandeiraea simplicifolia, Bauhinia purpurea, Caragan arobrescens, Cicer arietinum, Codium fragile, Datura stramonium, Dolichos biflorus, Erythrina corallodendron, Erythrina cristagalli, Euonymus europaeus, Glycine max, Helix aspersa, Helix pomatia, Lathyrus odoratus, Lens culinaris, Limulus polyphemus, Lysopersicon esculentum, Maclura pomifera, Momordica charantia, Mycoplasma gallisepticum, Naja mocambique , as well as the lectins Concanavalin A and Succinyl-Concanavalin A. Formation of Microspheres. As used herein, microspheres includes microparticles and microcapsules (having a core of a different material than the outer wall), having a diameter in the nanometer range up to 1 mm. The microsphere may consist entirely of bioadhesive polymer or have only an outer coating of bioadhesive polymer. Microspheres have been fabricated from the different polymers. Polylactic blank microspheres were fabricated by using two methods: solvent evaporation, as described by E. Mathiowitz, et al., J. Scanning Microscopy , 4, 329 (1990); L. R. Beck, et al., Fertil. Steril ., 31, 545 (1979); and S. Benita, et al., J. Pharm. Sci ., 73, 1721 (1984); and hot-melt microencapsulation, as described by E. Mathiowitz, et al., Reactive Polymers , 6, 275 (1987). Polyanhydrides made of bis-carboxyphenoxypropane and sebacic acid with molar ratio of 20:80 (P(CPP-SA) 20:80) (Mw 20,000) were prepared by hot-melt microencapsulation. Poly(fumaric-co-sebacic) (20:80) (Mw 15,000) blank microspheres were prepared by hot-melt microencapsulation. Polystyrene microspheres were prepared by solvent evaporation. Hydrogel microspheres were prepared by dripping the solution from a reservoir though a 250 microliter pipet tip into a stirred ionic bath. The specific conditions for alginate, chitosan, alginate/polyethylenimide (PEI) and carboxymethyl cellulose (CMC) are listed in Table 1. a. Solvent Evaporation. In this method the polymer is dissolved in a volatile organic solvent, methylene chloride. The drug (either soluble or dispersed as fine particles) is added to the solution, and the mixture is suspended in an aqueous solution that contains a surface active agent such as poly(vinyl alcohol). The resulting emulsion is stirred until most of the organic solvent evaporates, leaving solid microspheres. Several different polymer concentrations will be used (0.05-0.20 g/ml). The solution will be loaded with a drug and suspended in 200 ml of vigorously stirred distilled water containing 1% (w/v) poly(vinyl alcohol) (Sigma). After 4 hours of stirring, the organic solvent will have evaporated from the polymer, and the resulting microspheres are washed with water and dried overnight in a lyophilizer. Microspheres with different sizes (1-1000 microns) and morphologies can be obtained by this method. This method is useful for relatively stable polymers like polyesters and polystyrene. However, labile polymers, such as polyanhydrides, may degrade during the fabrication process due to the presence of water. For these polymers, the following two methods, which are performed in completely organic solvents, are more useful. b. Hot Melt Microencapsulation. In this method, the polymer is first melted and then mixed with the solid particles of the dye or drug that have been sieved to less than 50 microns. The mixture is suspended in a non-miscible solvent (like silicon oil), and, while stirring continuously, heated to 5° C. above the melting point of the polymer. Once the emulsion is stabilized, it is cooled until the polymer particles solidify. The resulting microspheres are washed by decantation with petroleum ether to give a free-flowing powder. Microspheres with sizes between one to 1000 microns can be obtained with this method. The external surfaces of spheres prepared with this technique are usually smooth and dense. This procedure is used to prepare microspheres made of polyesters and polyanhydrides. However, this method is limited to polymers with molecular weights between 1000-50000. c. Solvent Removal. This technique was primarily designed for polyanhydrides. In this method, the drug is dispersed or dissolved in a solution of the selected polymer in a volatile organic solvent like methylene chloride. This mixture is suspended by stirring in an organic oil (such as silicon oil) to form an emulsion. Unlike solvent evaporation, this method can be used to make microspheres from polymers with high melting points and different molecular weights. Microspheres that range between 1-300 microns can be obtained by this procedure. The external morphology of spheres produced with this technique is highly dependent on the type of polymer used. d. Hydrogel Microspheres. Microspheres made of gel-type polymers, such as alginate, are produced by dissolving the polymer in an aqueous solution, suspending the barium sulphate or any other active material in the mixture and extruding through a microdroplet forming device, producing microdroplets which fall into a hardening bath, that is slowly stirred. The advantage of these systems is the ability to further modify the surface of the microspheres by coating them with polycationic polymers, like polylysine after fabrication. Microsphere particles are controlled by using various size extruders. Table 1 summarizes the various hydrogels and the concentrations that were used to manufacture them. TABLE 1 Type and Concentration for Hydrogels Fabrication Hydrogel Hydrogel Conc. Bath Type/Conc. Stirring Chitosan 1.0% Tripolyphosphate, 3% 170 rpm Alginate 2.0% Calcium Chloride, 1.3% 160 rpm Alginate/PEI 2.0/6.0% Calcium Chloride, 1.3% 160 rpm CMC 2.0% Lead Nitrate, 10% 100 rpm Chitosan microspheres can be prepared by dissolving the polymer in acidic solution and crosslinking it with tripolyphosphate. Carboxymethyl cellulose (CMC) microspheres were prepared by dissolving the polymer in acid solution and precipitating the microsphere with lead ions. Alginate/polyethylene imide (PEI) were prepared in order to reduce the amount of carboxylic groups on the alginate microcapsule. Materials that can be Incorporated into the Microspheres. There is no specific limitation on the material that can be encapsulated within the bioadhesive polymer. Any kind of bioactive agent, including organic compounds, inorganic compounds, proteins, polysaccharides, or other materials can be incorporated using standard techniques. Examples of useful proteins include hormones such as insulin, growth hormones including somatometins, transforming growth factors, and other growth factors, antigens for oral vaccines, enzymes such as lactase or lipases, and digestive aids such as pancreatin. Examples of useful drugs include ulcer treatments such as Carafate from Marion Pharmaceuticals, antihypertensives or saluretics such as Metolazone from Searle Pharmaceuticals, carbonic anhydrase inhibitors such as Acetazolamide from Lederle Pharmaceuticals, insulin like drugs such as glyburide, a blood glucose lowering drug of the sulfonylurea class, hormones such as Android F from Brown Pharmaceuticals and Testred (methyltestosterone) from ICN Pharmaceuticals, antiparasitics such as mebeandazole (Vermox™, Jannsen Pharmaceutical. Other drugs for application to the vaginal lining or other mucosal membrane lined orifices such as the rectum include spermacides, yeast or trichomonas treatments and anti-hemorrhoidal treatments. In a preferred method for imaging, a radiopaque material such as barium is coated with polymer. Radioactive materials or magnetic materials could be used in place or, or in addition to, the radiopaque materials. Administration of Bioadhesive Microspheres to Patients. The microspheres are administered in suspension or in ointment to the mucosal membranes, via the nose, mouth, rectum, or vagina. Pharmaceutically acceptable carriers for oral or topical administration are known and determined based on compatibility with the polymeric material. Other carriers include bulking agents such as Metamucil™. These microspheres are especially useful for treatment of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. In ulcerative colitis, inflammation is restricted to the colon, whereas in Crohn's disease, inflammatory lesions may be found throughout the gastrointestinal tract, from the mouth to the rectum. Sulfasalazine is one of the drugs that is used for treatment of the above diseases. Sulfasalazine is cleaved by bacterial within the colon to sulfapyridine, an antibiotic, and to 5-amino salicylic acid, an anti-inflammatory agent. The 5-amino salicylic acid is the active drug and it is needed locally. Direct administration of the degradation product (5-amino salicylic acid) may be more beneficial. A bioadhesive drug delivery system could improve the therapy by retaining the drug for a prolonged time in the intestinal tract. For Crohn's disease, retention of 5-aminosalicylic acid in the upper intestine is of great importance, since bacteria cleave the sulfasalazin in colon, the only way to treat inflammations in the upper area is by local administration of 5-aminosalicylic acid. Gastrointestinal Imaging Barium sulphate suspension is the universal contrast medium used for examination of the upper gastrointestinal tract, as described by D. Sutton, Editor, A Textbook of Radiology and Imaging, Volume 2, Churchill Livingstone, London (1980), even though it has undesirable properties, such as unpalatability and a tendency to precipitate out of solution. Several properties are critical: (a) Particle size: the rate of sedimentation is proportional to particle size (i.e., the finer the particle, the more stable the suspension). (b) Non-ionic medium: charges on the barium sulphate particles influence the rate of aggregation of the particles. Aggregation is enhanced in the presence of the gastric contents. (c) Solution pH: suspension stability is best at pH 5.3. However, as the suspension passes through the stomach, it is inevitably acidified and tends to precipitate. The encapsulation of barium sulfate in microspheres of appropriate size provides a good separation of individual contrast elements and may, if the polymer displays bioadhesive properties, help in coating, preferentially, the gastric mucosa in the presence of excessive gastric fluid. With bioadhesiveness targeted to more distal segments of the gastrointestinal tract, it may also provide a kind of wall imaging not easily obtained otherwise. The double contrast technique, which utilizes both gas and barium sulphate to enhance the imaging process, especially requires a proper coating of the mucosal surface. To achieve a double contrast, air or carbon dioxide must be introduced. This is typically achieved via a nasogastric tube to provoke a controlled degree of gastric distension. Studies indicate that comparable results may be obtained by the release of individual gas bubbles in a large number of individual adhesive microspheres and that this imaging process may apply to intestinal segments beyond the stomach. An in vivo method for evaluating bioadhesion uses encapsulation of a radiopaque material, such as barium sulphate, or a gas-evolving agent, such as sodium carbonate, within a bioadhesive polymer. After oral administration of this radio-opaque material, its distribution in the gastric and intestinal areas is examined using image analysis. The present invention will be further understood by reference to the following non-limiting examples. EXAMPLE 1 Evaluation of Bioadhesive Properties of Polymeric Microspheres Polymers were evaluated for their bioadhesive potential using microspheres with diameters ranging from 700-800 μm and 700-2400 μm for the thermoplastics and hydrogels, respectively. The tensile type experiment used in this study offers several advantages over previous techniques. The setup enables one to determine bioadhesive forces between a single microsphere and intestinal mucosa. Since the experiment was conducted in an aqueous environment, problems in distinguishing between surface tension forces at the air/liquid interface and forces at the microsphere/mucus interface were eliminated. The results, shown in FIGS. 3 a , 3 b , and 3 c , demonstrate that polymers with higher concentrations of carboxylic acid groups such as alginate and polyanhydrides, produce greater bioadhesive bonds. The extremely high forces obtain for poly(fumaric-co-sebacic) anhydride (20:80) (50 mN/cm 2 ) indicate that bioerodible polymers are very promising bioadhesive delivery systems. The results also indicate that different fabrication methods which result in different morphologies exhibit different bioadhesive forces (e.g., PLA microspheres made by solvent evaporation adhere much stronger than PLA microspheres made by hot-melt microencapsulation). Comparison of the adhesive forces for polycarbophile, which was found to have good bioadhesive properties, show that polycarbophile displays bioadhesive forces of 1061 dyne/cm 2 (106.1 N/m 2 or 10.61 mN/cm 2 ) while most of the polymers described herein exhibit forces that range between 100 to 400 N/m 2 . EXAMPLE 2 Effect of Microsphere Diameter on Bioadhesive Forces. The effect of microsphere diameter on bioadhesive forces was investigated using P(CPP:SA) 20:80 and P(FA:SA) 20:80 microspheres ranging in size from 400 μm to 1700 μm, using the method described above. The results are shown in FIGS. 4 a , 4 b , 5 a , and 5 b . There was no decline in adhesive force with a decrease in microsphere diameter. To the contrary, the forces measured increase sharply as the diameters dropped below 750 μm to at least as low as 400 μm. EXAMPLE 3 In Vivo Transit Time Studies Using X-ray Imaging of Non-releasing Microspheres. A series of 10 rats were fed P(CPP-SA) 20:80 microspheres, as well as polystyrene microspheres, both loaded with barium sulphate. Each rat was fed 100 mg microspheres that were dispersed in 2 ml water. As controls, pure barium sulphate suspension in distilled water was fed to the rats. At given time intervals, the rats were X-rayed, and the distribution of the microspheres in the stomach and in the intestine was followed. The results are shown in FIGS. 6 and 7. It was observed that the polyanhydride and polystyrene microspheres were retained in the stomach for 11 to 16.5 hours while the barium sulphate was cleared from the stomach after 9 hours. Most of the barium sulphate was cleared from the intestine after 14 to 16 hours. Polystyrene microspheres were cleared from the gastrointestinal tract after the same time interval. However, it was observed that polyanhydride microspheres could still be found in the intestine even after 28 hours. Since normal transit time through the intestinal tract ranges between 4 to 12 hours, the results with polyanhydrides suggest bioadhesion of the microspheres which delays their passage through the gastrointestinal system. It is apparent that the smaller microspheres tend to have a longer retention time in the intestine. Comparing these results to the literature reveals that polycarbophiles with adhesive forces of 106 N/m 2 are retained 24 hr in the GI tract. Adhesive forces of about 200 N/m 2 yielded a retention time of 28 hr. Studies with microspheres containing barium sulfate demonstrated that some microspheres were retained in the gastrointestinal tract for as much as 28 hours. Using surface microscopy techniques, further analysis showed that the microspheres did tend to attach to the surface of the intestine. In a typical experiment, five rats were fed with polyanhydride microspheres made of poly[bis(p-carboxy phenoxy) propane-co-sebacic] (P[CPP-SA]) 20:80. The size of microspheres varied from 300 to 400 microns. 100 mg of spheres were suspended in 2 ml of distilled water and force-fed using a Gavage needle (gauge 16). Five hours after feeding, the rats were sacrificed by CO 2 asphyxiation and their intestines opened. Microspheres were found in the intestine, some sticking to the food, others adhering to the tissue. The areas with spheres adhering to the tissue were washed with saline. The tissue was fixed in neutral 10% formaldehyde solution for 24 hr. After fixation, the tissue was exposed to increasing concentrations of alcohol solutions, starting from 50:50% water and ethanol, and ending with 100% ethanol. At that stage, the tissue was dried using a CO 2 critical drying process. The dry samples were coated with gold-palladium and analyzed under a scanning electron microscope. A typical example of microspheres adhering to the intestine wall is shown in FIG. 8 . EXAMPLE 4 Preparation of Polyacrylamide Microspheres with High Bioadhesive Forces. Preparation of Microspheres. Polyacrylamide microspheres were produced by polymerizing an aqueous emulsion of acrylamide and bis methacrylamide in hexane. The following stock solutions were used: 1. 30% acrylamide (w/v), 10% bismethylacrylamide (w/v) in distilled water. The stock solution was treated with mixed bed ion-exchange resins to remove acrylic acid normally found in commercial preparations. 2. 1.2 M Tris pH 7.7. 3. 40% ammonium persulfate (w/v) 4. TEMED (N,N,N′,N′-Tetramethylethylenediamine 2 ml of the acrylamide stock, 1 ml of Tris stock, 0.1 ml of ammonium persulfate and 2 ml of distilled water to make a final volume of 5.1 ml of 12% acrylamide/4% bis methylacrylamide solution. This working solution was extensively degassed under water vacuum to remove dissolved oxygen which might inhibit the polymerization reaction. The acrylamide solution was added dropwise to 300 ml of n-hexane which was stirred at a rate of about 500 rpm with an overhead stirrer. Approximately 0.25 ml of SPAN 25 85 was added to the solution to prevent aggregation of the emulsion droplets. The stirring was generally maintained for 1-2 min until the emulsion reached the approximate desired size. To initiate polymerization, 1 ml of TEMED was added to the n-hexane phase and stirring was continued for 30 min. The beads were harvested and separated according to size by passing the solution through a series of graded sieves. Spheres having a diameter of between 300 and 800 μM were selected for further studies. EXAMPLE 5 Surface Activation of the Polyacrylamide Microspheres. Polyacrylamide microspheres were treated with 1 liter carbonyldimiazole (CDI) to covalently attach cation agents such as polyethyleneimine or poly-1-lysine. Typically one half-batch of the polyacrylamide beads were incubated with 0.5 M sodium carbonate for 1 hr at 60° C. with shaking. The sodium carbonate solution was changed twice with fresh solution during the incubation. This procedure is thought to hydrolyze the beads and produce free carboxyl groups which might be available for CDI reaction. Next the beads were solvent-exchanged with two changes of dry acetone and then incubated with 0.4% CDI (w/v) in acetone for 1 hr at 25° C. The incubation was repeated for an additional hour with fresh CDI solution. The beads were then washed twice with acetone to remove unbound CDI and then incubated with 10% polyethyleneimine (w/v), MW 1800) or else 1% poly-1-lysine in 0.2 M sodium borate buffer, pH 9.0 at 4° C. for 24 hrs. Alternatively, or in addition, one could add sialic acid to the polymer. The beads were washed twice with borate buffer and stored in 2 M ammonium chloride until needed. The ammonium chloride was used to inactivate “free” CDI binding sites. The beads were washed three times with 10 mM Tris, pH 7. immediately before use. Microspheres can be tested by the “Sprinkle Test” as follows. Microspheres are sprinkled over excised intestinal tissue segments. These segments were then placed in a buffer solution and left to incubate at 4° C. on a slowly moving shaker for 30 minutes. The samples were then analyzed with a dissecting stereo microscope. POLYMER COATING CAHN FORCE p(FA:SA) well coated approximately 26 mg polyacrylamide approximately 10 mg CDI/Polyacrylamide blanket of μspheres approximately 20 mg p(CPP:SA) scattered approximately 8 mg EXAMPLE 6 Comparative In Vitro Test of Bead Attachment to Rat Intestine Another way of comparing the relative bioadhesion capabilities of the microspheres was to incubate the different polymer particles with isolated rat intestine under physiological conditions. Typically, the jejunum from a newly sacrificed rat was removed, flushed with about 10 ml of Krebs Ringer saline, inverted on a stainless steel rod and divided into segments for testing. The segments were fashioned into empty sacs by attaching sutures to the cut ends. This step prevented the binding of microspheres to the serosal surface of the gut. The intestinal sacs were then incubated with a known number of microspheres of defined size range for a period of 30 min at 4° C. at shaking rate of about 30 r.p.m. At the end of the test period, the number of bead that attached to the intestine were counted as well as the number of unattached microspheres. The results of a typical experiment are described below. Polymer Attached Unattached Total P(CPP:SA) 24 261 285 P(FA:SA) 53 10 63 Acrylamid 113 220 330 CDI-Acryl 243 406 649 Polymer % Binding Sac Length Beads bound/cm sac P(CPP:SA) 8.4 3.0 cm 8 P(FA:SA) 84.1 4.8 cm 11 Acrylamide 33.9 2.8 cm 40 CDI-Acryl 37.4 4.1 cm 59 Modifications and variations of the method and bioadhesive microsphere compositions described herein will be obvious to those skilled in the art from the foregoing detailed description. Such modifications and variations are intended to come within the scope of the appended claims.

Bioadhesive polymers in the form of, or as a coating on, microcapsules containing drugs or bioactive substances which may serve for therapeutic, diagnostic, or diagnostic purposes in diseases of the gastrointestinal tract, are described. The polymeric microspheres all have a bioadhesive force of at least 11 mN/cm 2 (110 N/CM 2 ). Techniques for the fabrication of bioadhesive microspheres, as well as a method for measuring bioadhesive forces between microspheres and selected segments of the gastrointestinal tract in vitro are also described. This quantitative method provides a means to establish a correlation between the chemical nature, the surface morphology and the dimensions of drug-loaded microspheres on one hand and bioadhesive forces on the other, allowing the screening of the most promising materials from a relatively large group of natural and synthetic polymers which, from theoretical consideration, should be used for making bioadhesive microspheres.

TECHNICAL FIELD [0001] The present invention relates to a sample-and-hold method suitable for various data analyses. More particularly, it relates to a sample-and-hold method for reliably sampling and holding only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. BACKGROUND OF THE INVENTION [0002] It will be convenient for various data analyses if it is possible to sample and hold only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. [0003] For example, in monitoring visitors using a security camera installed at the door, a method is known which involves detecting a visitor's arrival using a sensor installed separately or based on changes in video images themselves or the like, and this detection is used as a trigger for storing video data for a fixed period after the detection (as described in the Japanese Patent Laid-Open Publication No. H04-32390). In so doing, in addition to the video data for the fixed period after the detection, if video data for a fixed period before the detection can also be stored, it will be possible to observe the visitor in greater detail by reproducing video images based on both sets of the stored data. [0004] Also, in the field of monitoring systems, a method is known which involves monitoring the state of an object based on measured data from two or more measuring instruments and a match between a feature value representing the measured data and a feature value representing occurrence of an expected event act as a trigger for storing the measured data for a fixed period after the trigger. In so doing, in addition to the measured data for the fixed period after the trigger, if measured data for a fixed period before the trigger can also be stored, both sets of the measured data stored will be useful in verifying the accuracy of detecting the occurrence of the event as well as in predicting the occurrence of the event. [0005] Furthermore, when monitoring the state of a car based on measured data from two or more measuring instruments, if it is possible to store not only measured data for a fixed period after an accident, but also measured data for a fixed period before an accident, using a match between a feature value representing the measured data and a feature value representing occurrence of the accident as a trigger, both sets of the measured data stored will be useful in investigating the cause of the accident. [0006] An object of the present invention is to provide a sample-and-hold method and apparatus which can reliably sample and hold only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. [0007] Another object of the present invention is to provide a sample-and-hold method and apparatus which can limit the storage capacity of storage media needed to achieve the above object to a bare minimum and can independently manage a series of data contained in a predetermined interval before the arrival time of a trigger signal and a series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. [0008] Still another object of the present invention is to provide a versatile semiconductor integrated circuit suitable for reliably sampling and holding only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. [0009] Other objects of the present invention will become readily apparent to those skilled in the art from the following description. BRIEF SUMMARY OF THE INVENTION [0010] The present invention provides a data string sample-and-hold method for sampling and holding only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. This method comprises a first step for preparing a primary storage medium in which a first storage area corresponding to the interval before the arrival time of the trigger signal and a second storage area corresponding to the interval after the arrival time of the trigger signal have been defined; a second step for continuing to write a series of incoming data into the first storage area using wrap-around addressing until the trigger signal arrives; and a third step for writing a series of data arriving after the arrival of the trigger signal into the second storage area instead of ceasing to write data into the first storage area when the trigger signal arrives. [0011] With this configuration, the series of data arriving before the arrival of the trigger signal is stored in the first storage area of the primary storage medium and the series of data arriving after the arrival of the trigger signal is stored in the second storage area of the primary storage medium. Thus, this method can limit the required storage capacity of storage media to a bare minimum and can independently manage the series of data contained in a predetermined interval before the arrival time of a trigger signal and the series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. [0012] If the primary storage medium is a nonvolatile storage medium such as an optical memory suitable for high-speed storage or a volatile storage medium such as a DRAM equipped with back-up power, even in incidences wherein power is shut down upon the arrival of the trigger signal, the series of data which arrive during the predetermined intervals before and after the arrival time of the trigger signal can be sampled and held in a reliable manner. [0013] The sample-and-hold method of the present invention may further comprise a fourth step of transferring the data written into the first and second storage areas of the primary storage medium to a secondary storage medium after the completion of the third step. [0014] With this configuration, the series of data arriving before the arrival of the trigger signal and stored in the first storage area of the primary storage medium as well as the series of data arriving after the arrival of the trigger signal and stored in the second storage area of the primary storage medium are transferred to the secondary storage medium. Thus, this method can limit the required storage capacity of storage media to a bare minimum and can independently and safely manage the series of data contained in a predetermined interval before the arrival time of a trigger signal and the series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. Moreover, since sampled and held data strings are eventually stored in the secondary storage medium, the waiting operation for the next sample-and-hold operation is not hindered. [0015] Here, if the primary storage medium is a volatile storage medium such as a DRAM suitable for high-speed storage and secondary storage medium is a nonvolatile storage medium such as a flash memory or hard disk, it is possible to ensure high memory speed and safety of stored data. [0016] In the two sample-and-hold methods described above, preferably the storage capacity of the first storage area is an integral multiple of the storage capacity of the second storage area (more preferably the former is twice the latter) This will make it easy to collate the data stored in the first storage area and data stored in the second storage area in units of data strings (frames) when image data or voice data divided into frames are handled. [0017] The present invention provides a sample-and-hold apparatus for sampling and holding only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. This apparatus comprises a primary storage medium; an area definition data storage means for storing area definition data that defines a first storage area which corresponds to the interval before the arrival time of the trigger signal and a second storage area which corresponds to the interval after the arrival time of the trigger signal in the primary storage medium; a first write control means for continuing to write a series of incoming data into the first storage area defined by the area definition data, using wrap-around addressing until the trigger signal arrives; and a second write control means for writing a series of data arriving after the arrival of the trigger signal into the second storage area defined by the area definition data instead of ceasing to write data into the first storage area when the trigger signal arrives. [0018] With this configuration, the series of data arriving before the arrival of the trigger signal is stored in the first storage area of the primary storage medium and the series of data arriving after the arrival of the trigger signal is stored in the second storage area of the primary storage medium. Thus, this method can limit the required storage capacity of storage media to a bare minimum and can independently manage the series of data contained in a predetermined interval before the arrival time of a trigger signal and the series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. [0019] If the primary storage medium is a nonvolatile storage medium such as an optical memory suitable for high-speed storage or a volatile storage medium such as a DRAM equipped with back-up power, even in incidences wherein power is shut down upon the arrival of the trigger signal, the series of data which arrive during the predetermined intervals before and after the arrival time of the trigger signal can be sampled and held in a reliable manner. [0020] The sample-and-hold apparatus of the present invention may further comprise a secondary storage medium; and a data transfer control means for transferring the data written into the first and second storage areas of the primary storage medium to a secondary storage medium. [0021] With this configuration, the series of data arriving before the arrival of the trigger signal and stored in the first storage area of the primary storage medium as well as the series of data arriving after the arrival of the trigger signal and stored in the second storage area of the primary storage medium are transferred to the secondary storage medium. Thus, this method can limit the required storage capacity of storage media to a bare minimum and can independently and safely manage the series of data contained in a predetermined interval before the arrival time of a trigger signal and the series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. Moreover, since sampled and held data strings are eventually stored in the secondary storage medium, the waiting operation for the next sample-and-hold operation is not hindered. [0022] Here, if the primary storage medium is a volatile storage medium such as a DRAM suitable for high-speed storage and secondary storage medium is a nonvolatile storage medium such as a flash memory or hard disk, it is possible to ensure high memory speed and safety of stored data. [0023] The sample-and-hold apparatus of the present invention may comprise area definition data generating means for internally generating area definition data based on input data from outside. As described above, the “area definition data” is data that defines the first storage area corresponding to the interval before the arrival time of the trigger signal and the second storage area corresponding to the interval after the arrival time of the trigger signal in the primary storage medium. The area definition data can be given as the starting address and ending address of each of the areas, maximum byte count from the starting address, or the like. This configuration makes it possible to configure the area definition data properly by providing input data from outside. [0024] Here, the input data from outside may contain both data indicating the capacity of the first storage area and data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based on the two sets of data. This configuration makes it possible to set the first storage area and second storage area individually to any desired capacity by providing input data from outside. [0025] Alternatively, the input data from outside may contain data indicating the capacity of the first storage area, but not data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based only on the data indicating the capacity of the first storage area. This configuration makes it possible to set the capacity of the first storage area and capacity of the second storage area properly by simply supplying input data which represents only the capacity of the first storage area, provided that an appropriate correlation between the capacity of the first storage area and capacity of the second storage area is defined in advance. [0026] In the two sample-and-hold apparatus described above, preferably the storage capacity of the first storage area is an integral multiple of the storage capacity of the second storage area (more preferably the former is twice the latter). This will make it easy to collate the data stored in the first storage area and data stored in the second storage area in units of data strings when image data or voice data divided into frames are handled if the capacity of the second storage area is related to the size of, for example, the frame in advance. [0027] Viewed from another angle, the present invention provides a highly versatile semiconductor integrated circuit suitable for implementing the above methods and apparatus. The semiconductor integrated circuit comprises a first port which a series of data to be sampled are inputted; a second port which a predetermined trigger signals are inputted; a third port connected to a predetermined storage medium; a fourth port which outputs series of sampled and held data; an area definition data storage means for storing area definition data which defines a first storage area and a second storage area in the storage medium connected to the third port; a first write control means for continuing to write a series of data inputted through the first port into the first storage area of the storage medium connected to the third port, using wrap around addressing until a trigger signal is inputted through the second port; a second write control means for writing a series of data arriving after the arrival of the trigger signal into the second storage area of the storage medium instead of ceasing to write data into the first storage area of the storage medium when the trigger signal is inputted through the second port; and data read control means for performing control over transmission of data stored in the first storage area and the second storage area of the storage medium connected with the third port to the fourth port. [0028] With this configuration, simply by inputting a series of data to be sampled to the first port and inputting a predetermined trigger signal to the second port with the primary storage medium connected to the third port, the first and second storage areas can be defined properly in the primary storage medium. Furthermore, upon the arrival of the trigger signal, the data string in a fixed interval immediately before the arrival of the trigger signal is stored in the first storage area of the primary storage medium and the data string in a fixed interval immediately after the arrival of the trigger signal is stored in the second storage area of the primary storage medium. Subsequently, the data strings stored in the primary storage medium are read to the outside through the fourth port. [0029] If the primary storage medium is a nonvolatile storage medium such as an optical memory suitable for high-speed storage or a volatile storage medium such as a DRAM equipped with back-up power, even in incidences wherein power is shut down (e.g., due to a car crash or the like when the semiconductor integrated circuit is used as an in-car data logger) upon the arrival of the trigger signal, the series of data which arrive during the predetermined intervals before and after the arrival time of the trigger signal can be sampled and held in a reliable manner. [0030] The first to fourth ports described above are not necessarily meant to be independent of each other. A single port may implement the functions of two or more ports. For example, A single physical port may combine the function of the first port to input series of data to be sampled and the function of the second port to input predetermined trigger signals. [0031] The semiconductor integrated circuit of the present invention may comprise a power controller for supplying power not only in the semiconductor integrated circuit, but also to the storage medium connected externally, and to an oscillator connected externally and supplies an operation clock to the semiconductor integrated circuit. Since this configuration eliminates the need for a power supply to the storage medium and to the clock oscillator, it simplifies design accordingly. Here, if the semiconductor integrated circuit is equipped with an external terminal for connecting a super capacitor which maintains electric power supplied from the power controller for a predetermined time during a power failure, then by connecting a super capacitor to the circuit, it is possible to keep the operation clock oscillator and storage medium functioning properly even in case of a power failure upon arrival of a trigger signal, and thereby ensuring the reliability of sample-and-hold operations. [0032] The semiconductor integrated circuit of the present invention may comprise a fifth port which control data are inputted; and an area definition data generating means for internally generating area definition data based on the control data inputted through the fifth port. This configuration makes it possible to set up appropriate storage areas according to various sampling data by inputting appropriate control data to the fifth port from outside. [0033] Here, the control data from outside may contain both data indicating the capacity of the first storage area and data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based on the two sets of data. This configuration makes it possible to set the first storage area and second storage area individually to any desired capacity by providing input data from outside. [0034] Alternatively, the control data from outside may contain data indicating the capacity of the first storage area, but not data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based only on the data indicating the capacity of the first storage area. This configuration makes it possible to set the capacity of the first storage area and capacity of the second storage area properly by simply supplying control data which represents only the capacity of the first storage area, provided that an appropriate correlation between the capacity of the first storage area and capacity of the second storage area is defined in advance. [0035] Viewed from another angle, the present invention provides a semiconductor integrated circuit comprising: a first port which series of data to be sampled are inputted; a second port which predetermined trigger signals are inputted; a third port connected to a predetermined primary storage medium; a fourth port connected to a predetermined secondary storage medium; a fifth port which reads sampled and held data; an area definition data storage means for storing area definition data which defines a first storage area and a second storage area in the primary storage medium connected to the third port; a first write control means for continuing to write a series of data inputted through the first port into the first storage area of the primary storage medium connected to the third port, using wrap around addressing until a trigger signal is input through the second port; a second write control means for writing a series of data arriving after the arrival of the trigger signal into the second storage area of the primary storage medium instead of ceasing to write data into the first storage area of the primary storage medium when the trigger signal is inputted through the second port; a data transfer control means for transferring the data written into the first and second storage areas of the primary storage medium connected with the third port to a secondary storage medium connected with the fourth port; and a data read control means for performing control over transmission of data stored in the secondary storage medium connected with the fourth port to the fifth port. [0036] With this configuration, simply by inputting a series of data to be sampled to the first port and inputting a predetermined trigger signal to the second port with the primary storage medium connected to the third port and the secondary storage medium connected to the fourth port, the first and second storage areas can be defined properly in the primary storage medium. Furthermore, upon the arrival of the trigger signal, the data string in a fixed interval immediately before the arrival of the trigger signal is stored in the first storage area of the primary storage medium and the data string in a fixed interval immediately after the arrival of the trigger signal is stored in the second storage area of the primary storage medium, and then the data strings are transferred to the secondary storage medium. Subsequently, the data strings stored in the secondary storage medium are read to the outside through the fourth port. [0037] Here, if the primary storage medium is a nonvolatile storage medium such as a DRAM suitable for high-speed storage and secondary storage medium is a nonvolatile storage medium such as a flash memory or hard disk, it is possible to ensure high memory speed and safety of stored data. [0038] The semiconductor integrated circuit of the present invention may comprise a power controller for supplying power not only in the semiconductor integrated circuit, but also to the primary and secondary storage media connected externally, and to an oscillator connected externally and supplies an operation clock to the semiconductor integrated circuit. Since this configuration eliminates the need for a power supply on the primary and secondary storage media and on the clock oscillator, it simplifies design accordingly. Here, if the semiconductor integrated circuit is equipped with an external terminal for connecting a super capacitor which maintains electric power supplied from the power controller for a predetermined time during a power failure, then by connecting a super capacitor to the circuit, it is possible to keep the operation clock oscillator and primary and secondary storage media functioning properly even in case of a power failure upon arrival of a trigger signal, and thereby ensure the reliability of sample-and-hold operations. For example, even in incidences wherein power is shut down (e.g., due to a car crash or the like when the semiconductor integrated circuit is used as an in-car data logger) upon the arrival of the trigger signal, the series of data which arrive during predetermined intervals before and after the arrival time of the trigger signal can be sampled and held reliably in the primary storage medium, and then transferred and saved in the secondary storage medium. [0039] The semiconductor integrated circuit of the present invention may comprise a sixth port which control data are inputted; and an area definition data generating means for internally generating area definition data based on the control data inputted through the sixth port. This configuration makes it possible to set up appropriate storage areas according to various sampling data by inputting appropriate control data to the sixth port from outside. [0040] Here, the control data from outside may contain both data indicating the capacity of the first storage area and data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based on the two sets of data. This configuration makes it possible to set the first storage area and second storage area individually to any desired capacity by providing input data from outside. [0041] Alternatively, the control data from outside may contain data indicating the capacity of the first storage area, but not data indicating the capacity of the second storage area, and the area definition data generating means may generate area definition data based only on the data indicating the capacity of the first storage area. This configuration makes it possible to set the capacity of the first storage area and capacity of the second storage area properly by simply supplying control data which represents only the capacity of the first storage area, provided that an appropriate correlation between the capacity of the first storage area and capacity of the second storage area is defined in advance. [0042] In the two sample-and-hold apparatus described above, preferably the storage capacity of the first storage area is an integral multiple of the storage capacity of the second storage area (more preferably the former is twice the latter). This will make it easy to collate the data stored in the first storage area and data stored in the second storage area in units of data strings when image data or voice data divided into frames are handled if the capacity of the second storage area is related to the size of the frame in advance. [0043] The sample-and-hold method and apparatus according to the present invention can reliably sample and hold only series of data which arrive during predetermined intervals before and after the arrival time of a predetermined trigger signal, out of a series of data which arrives successively. [0044] The sample-and-hold method and apparatus according to the present invention can limit the required storage capacity of storage media to a bare minimum and can independently manage a series of data contained in a predetermined interval before the arrival time of a trigger signal and a series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. [0045] Furthermore, with the semiconductor integrated circuit for sampling and holding according to the present invention, simply by inputting a series of data to be sampled to the first port and inputting a predetermined trigger signal to the second port with the primary storage medium and/or the secondary storage medium each connected to an appropriate port, the first and second storage areas can be defined properly in the primary storage medium. Furthermore, upon the arrival of the trigger signal, the data string in a fixed interval immediately before the arrival of the trigger signal is stored in the first storage area of the primary storage medium and the data string in a fixed interval immediately after the arrival of the trigger signal is stored in the second storage area of the primary storage medium. Also, the data strings are transferred to the secondary storage medium as required. Subsequently, the data strings stored in the primary storage medium or secondary storage medium can be read to the outside through a predetermined port. BRIEF DESCRIPTION OF THE DRAWINGS [0046] FIG. 1 is a block diagram of a sample-and-hold apparatus according to the present invention; [0047] FIG. 2 is a general flowchart showing operation of the control CPU; [0048] FIG. 3 is a detailed flowchart of a settings process; [0049] FIG. 4 is an explanatory diagram illustrating a memory map of a primary storage medium and format of stored data; [0050] FIG. 5 is a general flowchart showing operation of a memory controller; [0051] FIG. 6 is a detailed flowchart of a sample-and-hold process; [0052] FIG. 7 is an explanatory diagram illustrating operation of the present invention; [0053] FIG. 8 is a block diagram of a data recorder to which a sample-and-hold IC according to the present invention is applied; and [0054] FIG. 9 is a block diagram of a monitoring device to which the sample-and-hold IC according to the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0055] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. It should be noted that the scope of the present invention is not limited by the embodiment described below and is defined only by the appended claims. [0056] A block diagram of a sample-and-hold apparatus according to the present invention is shown in FIG. 1 . As shown in the figure, the sample-and-hold apparatus comprise mainly of a semiconductor integrated circuit 1 specifically designed for sampling and holding, DRAM 2 which functions as a primary storage medium, flash memory (FLASH) 3 which functions as a secondary storage medium, and clock oscillator 4 which supplies an operation clock to the semiconductor integrated circuit 1 . [0057] The semiconductor integrated circuit 1 is equipped with a plurality of external ports. A port P 11 receives parallel inputs of series of data to be sampled. In FIG. 1 , P-DATA (IN) indicates parallel input data. A port P 12 receives serial inputs of series of data to be sampled. In FIG. 1 , S-DATA (IN) indicates serial input data. In this way, the semiconductor integrated circuit 1 can be inputted with series of data to be sampled, both as parallel data and as serial data. [0058] A port P 2 is inputted with a predetermined trigger signal. In FIG. 1 , TRG indicates the trigger signal. As described in detail later, the semiconductor integrated circuit 1 can sample and hold only the data strings which arrive during predetermined intervals before and after the arrival of the trigger signal TRG, out of the series of data to be sampled inputted through the port P 11 or P 12 . [0059] A port P 3 is used to connect the DRAM 2 , a primary storage medium. As described in detail later, as a result of a sample-and-hold process, the data strings which arrive during predetermined intervals before and after the arrival of the trigger signal TRG are stored first in the DRAM 2 which is a primary storage medium. The DRAM 2 draws power PW 2 from the semiconductor integrated circuit 1 . [0060] A port P 4 is used to connect the flash memory (FLASH) 3 , a secondary storage medium. As described in detail later, the sample-and-hold data stored in the DRAM 2 is transferred and saved in the flash memory (FLASH) 3 upon completion of the sample-and-hold process. The flash memory (FLASH) 3 also draws power PW 3 from the semiconductor integrated circuit 1 . [0061] A port P 5 is used to read held data to the outside. In FIG. 1 , H-DATA (OUT) indicates the sample-and-hold data read out. According to this embodiment, the sample-and-hold data H-DATA (OUT) is read out of the flash memory (FLASH) 3 and is outputted to the outside via the port P 5 . [0062] A port P 6 is used to send control data and the like from a personal computer (PC) to the semiconductor integrated circuit 1 . According to this embodiment, USB is used for communications with the personal computer (PC), but the communication method is not limited to the use of USB. [0063] A port P 7 is used to supply the operation clock CLK 0 generated by the clock oscillator 4 to the semiconductor integrated circuit 1 . That is, the semiconductor integrated circuit 1 comprise of a clock-synchronized wired logic circuits as described in detail later, and the operation clock CLK 0 needed for the operation of the clock-synchronized wired logic circuit is supplied from the clock oscillator 4 via the port P 7 . The clock oscillator 4 also draws power PW 4 from the semiconductor integrated circuit 1 . [0064] Next, major external terminals will be described. An external terminal T 1 is used to supply power VDD to the semiconductor integrated circuit 1 . The power VDD supplied through the external terminal T 1 is supplied to a power controller 180 in the semiconductor integrated circuit 1 . The power controller 180 stabilizes and regulates the supplied power VDD, and thereby outputs power in four systems, PW 1 to PW 4 , of which the power PW 1 is supplied to various circuits in the semiconductor integrated circuit 1 . As described above, the power PW 2 is supplied to the DRAM 2 connected to the port P 3 , the power PW 3 is supplied to the flash memory (FLASH) 3 connected to the port P 4 , and the power PW 4 is supplied to the clock oscillator 4 connected to the port P 7 . External terminals T 2 and T 3 are used to connect a super capacitor 5 externally. Electric charges stored in the super capacitor 5 are used to maintain the power in four systems PW 1 to PW 4 outputted from the power controller 180 for a predetermined period of time during a power failure. In this example, the capacity of the super capacitor 5 has been determined such that even in incidences wherein the power VDD is interrupted immediately after arrival of the trigger signal TRG, the power PW 1 to PW 4 will be maintained properly at least until a sample-and-hold operation and transfer operation are completed. [0065] Next, an internal configuration of the semiconductor integrated circuit 1 will be described in detail. The semiconductor integrated circuit 1 contains a memory controller 110 , a control CPU 120 , a header addition controller 130 , a data bit controller 140 , a serial/parallel converter 150 , a serial/parallel switching controller 160 , an OR gate 170 , the power controller 180 (described above), and interface circuits 101 to 105 corresponding to the ports P 12 , P 11 , P 2 to P 7 described above. [0066] The memory controller 110 comprise of a clock-synchronized wired logic circuit which implements a control function for DMA transfer of the parallel input data P-DATA (IN) from the port P 11 or the serial input data S-DATA (IN) from the port P 12 to the first and second storage areas (described in detail later) of the DRAM 2 , a control function for DMA transfer of the data stored in the first and second storage areas of the DRAM 2 to a predetermined area in the flash memory (FLASH) 3 , a control function for reading the data stored in the predetermined area in the flash memory (FLASH) 3 to the outside via the port P 5 , and other functions. The memory controller 110 contains a DMA controller (DMAC) 110 a and flash memory (FLASH) 10 b . The DMA controller (DMAC) 110 a is used for the data transfer functions described above. The flash memory (FLASH) 110 b stores area definition data which defines the first and second storage areas of the DRAM 2 , area definition data which defines storage areas in the flash memory (FLASH) 3 , and other data. These storage area definition data are rewritable from external PCs via the control CPU 120 as described in detail later. Consequently, the semiconductor integrated circuit 1 is versatile enough to be compatible with any data string and sample-and-hold specification. The functions of the memory controller 110 will be described in detail later with reference to flowcharts in FIGS. 5 and 6 . [0067] The control CPU 120 comprise mainly of a microprocessor. The control CPU 120 has (1) a function for performing various setting processes based on input data from the user while conducting communications with a PC connected to the port P 6 via an USB interface 105 , (2) a function for performing various system support processes and the like by centrally controlling the memory controller 110 , header addition controller 130 , and data bit controller 140 . The control CPU 120 contains a flash memory (FLASH) 120 a . The flash memory (FLASH) 120 a stores various data loaded by the user via the PC. The functions of the control CPU 120 will be described in detail later with reference to flowcharts in FIGS. 2 and 3 . [0068] The header addition controller 130 comprise of a wired logic circuit which adds header information to the parallel input data P-DATA (IN) supplied via the port P 11 and the serial input data S-DATA (IN) supplied via the port P 12 (see FIG. 4 ( b )). In FIG. 4 ( b ), reference numeral 403 denotes a data section and reference numeral 404 denotes a header section. The header information added here contains at least numeric information representing the order of incoming series of data. The numeric information is added cycling between predetermined minimum and maximum values. Later, sample-and-hold data is read and organized based on this numeric information which represents the data order. [0069] The data bit controller 140 controls data bits with respect to the header addition controller 130 , serial/parallel converter 150 , parallel interface 101 , and serial interface 102 under the control of the control CPU 120 . The data bit control allows the header addition controller 130 to add header information to specified bits, allows the serial/parallel converter 150 to perform serial/parallel conversion of data bit strings properly, and allows the interfaces 101 and 102 to recognize input data bits properly. [0070] The serial/parallel converter 150 is a circuit converting the serial input data S-DATA (IN) supplied to the port P 12 and taken in through the serial interface 102 into parallel data. The resulting parallel data is supplied to the header addition controller 130 (described above) via the OR gate 170 . [0071] The serial/parallel switching controller 160 activates either the parallel interface 101 or serial interface 102 selectively under the control of the data bit controller 140 . Proper functioning of the serial/parallel switching controller 160 allows the semiconductor integrated circuit 1 to handle both serial input data and parallel input data. [0072] A clock controller 190 generates and outputs n types of control clock CLK 1 to CLKn based on the operation clock CLK 0 supplied from the clock oscillator 4 via the port P 7 , clock CLK(P) taken in through the parallel interface 101 , and clock CLK(S) taken in through the serial interface 102 . The control clocks CLK 1 to CLKn thus obtained are supplied, as required, to various circuits in the semiconductor integrated circuit 1 , contributing to normal operation of the clock-synchronized wired logic circuits. The clock controller 190 contains a phase-locked loop (PLL) circuit 190 a , which synchronizes various clocks and helps synthesize frequencies. [0073] Next, the functions of the control CPU 120 will be described in detail with reference to the flowcharts in FIGS. 2 and 3 . As described above, the control CPU 120 is mainly designed to perform system support processes and settings processes. [0074] A general flowchart showing operation of the control CPU is shown in FIG. 2 . In the figure, as processing starts upon power-on, the control CPU 120 conducts communications with the PC connected to the port P 6 via the USB interface 105 . The control CPU 120 receives information from the PC and stores the information in the flash memory 120 a (Step 201 ). This information includes control information on operation mode flags, thereby allowing the PC to switch the operation mode of the control CPU 120 . Following the receiving process (Step 201 ), the control CPU 120 performs operation mode determining process (Step 202 ). If the operation mode is determined to be Setting mode, the control CPU 120 performs a settings process (Step 203 ). On the other hand if the operation mode is determined to be Run mode, the control CPU 120 performs a system support process (Step 204 ). In the settings process (Step 203 ), the control CPU 120 sets the arrival speed of the data to be sampled, data format, hold period before the trigger, and hold period after the trigger and performs other settings according to various sample-and-hold specifications. As described in detail later, the settings process (Step 203 ) includes area definition data generating process which defines the first and second storage areas. On the other hand, in the system support process (Step 204 ), the control CPU 120 controls the memory controller 110 , header addition controller 130 , and data bit controller 140 , and thereby supports the system in the semiconductor integrated circuit 1 , as described above. [0075] A detailed flowchart of the settings process (Step 203 ) is shown in FIG. 3 . This flowchart shows only the generating process of the storage area definition data out of the settings process (Step 203 ). In the figure, as processing starts, the control CPU 120 reads instruction command out of data received from the PC and decodes them (Step 301 ). Only when the decoded instruction is determined to be an instruction to define a storage area (Step 302 : YES), the control CPU 120 performs the subsequent processes. Otherwise (Step 302 : NO), the control CPU 120 performs other appropriate process according to the decoded instruction. [0076] If the decoded instruction is determined to be an instruction to define a storage area (Step 302 : YES), the control CPU 120 subsequently determines the type of the specification method to be used. According to this embodiment, when sampling and holding data strings which arrive during predetermined intervals before and after a triggering time, one of two specification methods can be selected: one of the methods involves specifying the preceding and succeeding intervals separately to define storage areas and the other method involves specifying only the preceding interval, leaving the succeeding interval to be defined automatically according to a predetermined algorithm. If it is determined that both intervals are specified (Step 303 ), the control CPU 120 subsequently determines the unit used to specify the data used (Step 304 ). In this example, two units are available to specify the length of the intervals before and after the trigger time: namely “time duration” and “data quantity.” If it is determined that “time duration” is used, the time duration is converted into data quantity (Step 305 ). On the other hand, if it is determined that “data quantity” is used, the unit is left as it is. Then, a first storage area is defined in the DRAM 2 based on the data quantity in the preceding interval (Step 306 ). The first storage area is defined by calculating the starting address AD 11 and the ending address AD 12 of the first storage area 401 , as shown in FIG. 4 ( a ). Then, a second storage area is defined in the DRAM 2 based on the data quantity in the succeeding interval. The second storage area is defined by calculating the starting address AD 21 and the ending address AD 22 of the second storage area 402 in the DRAM 2 , as shown in FIG. 4 ( a ). The storage area definition data (AD 11 , AD 12 , AD 21 , and AD 22 ) obtained in the above processes (Steps 306 and 307 ) are transmitted to the memory controller 110 and stored in the flash memory 110 b in the memory controller 110 . Subsequently, the memory controller 110 perform data transfer process to the DRAM 2 via the data input port P 11 or P 12 , performs data transfer process from the DRAM 2 to the flash memory (FLASH) 3 , and performs data transfer process from the flash memory (FLASH) 3 to the output port P 5 by referring to the storage area definition data (AD 11 , AD 12 , AD 21 , and AD 22 ) stored in the flash memory 110 b , as required. [0077] Next, operation of the memory controller 110 will be described. A general flowchart showing the operation of the memory controller is shown in FIG. 5 . In the figure, as processing starts, the memory controller 110 determines whether a sample-and-hold instruction has been given by the control CPU 120 (Step 501 ) or whether a read instruction has been given (Step 502 ). If a sample-and-hold instruction has been given (Step 501 : YES), the memory controller 110 performs a sample-and-hold process (Step 503 ). On the other hand, if a read instruction has been given (Step 502 : YES), the memory controller 110 performs a held-data reading process (Step 504 ). In the held-data reading process (Step 504 ), the held data H-DATA (OUT) stored in the flash memory 3 is transferred to the data output port P 5 . [0078] A detailed flowchart of the sample-and-hold process is shown in FIG. 6 . In the figure, as processing starts, a formatting process is performed first to format the DRAM 2 and flash memory (FLASH) 3 (Step 601 ). [0079] Then, after setting the starting address AD 11 and ending address AD 12 of the first storage area in the DMA controller (DMAC) 110 a , the memory controller 110 starts up the DMA controller (DMAC) 110 a (Step 603 ), thereby starting a DMA transfer of the data strings taken in from the header addition controller 130 to the first storage area 401 in the DRAM 2 . If the parallel input port P 11 has been selected by the serial/parallel switching controller 160 , parallel input data P-DATA (IN) is transferred to the first storage area 401 in the DRAM 2 . On the other hand, if the serial input port P 12 has been selected, serial input data S-DATA (IN) is transferred to the first storage area 401 in the DRAM 2 . Thus, the series of data strings arriving from the parallel input port P 11 or serial input port P 12 is written in sequence into the first storage area 401 shown in FIG. 4 ( a ), beginning with the starting address AD 11 to the ending address AD 12 . On the other hand, during the DMA transfer process, the memory controller 110 constantly checks for an arrival of a trigger signal TRG (Step 604 ) as well as a match between a transfer address AD and the ending address AD 12 (Step 605 ). Each time a transfer address AD matches the ending address AD 12 of the first storage area 401 (Step 605 : YES), the DMA controller (DMAC) 110 a is restarted (Step 603 ). Consequently, when the data writing process for writing into the first storage area 401 from the starting address AD 11 to the ending address AD 12 is completed, data is written into the first storage area 401 beginning with the starting address AD 11 again, and thus overwriting process of the previous data is performed repeatedly. That is, the data strings which arrives via the data input port P 11 or P 12 are written into the first storage area 401 defined in the DRAM 2 on a so-called FIFO (First In First Out) basis with write addresses AD progressing in a wrap-around manner by the memory controller 110 . [0080] In this state, if a trigger signal TRG arrives at the port P 2 and the arrival of the trigger is verified (Step 604 : YES), the memory controller 110 sets the starting address AD 21 and ending address AD 22 of the second storage area 402 in the DMA controller (DMAC) 110 a (Step 606 ), and then starts up the DMA controller (DMAC) 110 a (Step 607 ), thereby starting a DMA transfer process to the second storage area 402 . Consequently, the data strings supplied to the data input port P 11 or P 12 are transferred and stored in the second storage area 402 in the DRAM 2 via the header addition controller 130 . Subsequently, when a destination address AD matches the ending address AD 22 of the second storage area 402 (Step 608 : YES), the transfer process to the second storage area 402 in the DRAM 2 is completed. [0081] In this way, the series of data in a predetermined interval before the arrival of the trigger signal TRG is stored in the first storage area 401 and the series of data in a predetermined interval after the arrival of the trigger signal TRG is stored in the second storage area 402 . [0082] Then, the series of data extracted from the predetermined intervals before and after the arrival of the trigger and stored in the first storage area 401 and second storage area 402 in the DRAM 2 are transferred and saved in a predetermined area in the flash memory (FLASH) 3 . Subsequently, even in incidences wherein power is shut down, the series of data in the flash memory (FLASH) 3 are retained securely. [0083] Returning to FIG. 5 , if a read instruction is given from a PC or the like (Step 502 : YES), the memory controller 110 performs the held-data reading process (Step 504 ) to read the held data H-DATA (OUT) stored in a predetermined area in the flash memory 3 to the outside via the output port P 5 . In doing so, if the held data H-DATA (OUT) is read to the outside via the output port P 5 after being sorted in the order of arrival based on the header information (header section 403 ) in the flash memory 3 , this will save the trouble of sorting the held data later, and thus make it easy to handle the held data. [0084] According to this embodiment, since the super capacitor 5 is connected between the external terminals T 2 and T 3 , even if the power VDD supplied to the external terminal T 1 is interrupted, the power in four systems PW 1 to PW 4 outputted from the power controller are maintained properly at least until the data writing operation into the second storage area 402 and data transfer from the DRAM 2 to the flash memory (FLASH) 3 are completed after the arrival of the trigger signal. Thus, for example, if the sample-and-hold apparatus is used as an in-car accident recorder or the like, when a trigger occurs as a result of an accident shutting down the power, it is possible to sample and hold various data at the time of the accident for predetermined periods of time before and after the accident, transfer and save the data in the flash memory 3 , and use it to investigate the cause of the accident. [0085] FIG. 7 is an explanatory diagram illustrating the operation of the present invention. Suppose arbitrary analog data are arriving in time sequence as shown in FIG. 7 ( a ). If, for example, the value of input data exceeds a predetermined threshold value TH, generating a trigger signal as shown in FIG. 7 ( b ), only the data strings which arrive during intervals within T 1 seconds before or T 2 seconds after the arrival of the trigger signal are sampled and held as shown in FIG. 7 ( c ). In this example, the intervals have been set so as to satisfy the relationship T 1 = 2 ×T 2 . Thus, when the sample-and-hold apparatus is used as an in-car accident recorder or the like, if the sample-and-hold apparatus is started up by a trigger signal generated by an airbag activation signal as soon as an accident occurs, series of data can be sampled and held for T 1 seconds before and T 2 seconds after the accident and saved in the flash memory (FLASH) 3 . Consequently, if the apparatus is contained in a relatively rigid casing, the saved data read from the flash memory (FLASH) 3 after the accident will help investigate the cause of the accident. [0086] In the above embodiment, the flash memory (FLASH) 3 is used as a secondary storage medium to make sure that sample-and-hold data is saved reliably, but it is not strictly necessary to provide a secondary storage medium if the stored data in the DRAM 2 can be retained for a week to a month, which can be achieved by increasing the capacity of the super capacitor 5 . In that case, the transfer process (Step 609 ) from the DRAM 2 to the flash memory (FLASH) 3 can be omitted from the detailed flowchart of the sample-and-hold process shown in FIG. 6 . [0087] As described above, according to this embodiment, by simply connecting the data strings to be sampled to the port P 11 or P 12 , trigger signals to the port P 2 , the DRAM 2 to the port P 3 , the flash memory (FLASH) 3 to the port P 4 , and the clock oscillator 4 to the port P 7 , it is possible, upon arrival of a trigger signal TRG, to sample and hold, only the series of data arriving during predetermined intervals before and after the arrival of the trigger signal TRG in the first storage area 401 and second storage area 402 of the DRAM 2 , and save the content immediately in the flash memory (FLASH) 3 . Then, if a read command is given from a PC, the sample-and-hold data stored in the flash memory (FLASH) 3 can be read out to the port P 5 by the memory controller 110 . Header information is included by the header addition controller 130 in each item of the data read out and the header information contains a numeric value which represents data order. Thus, the sample-and-hold data read out can be sorted easily in time sequence based on the numeric values. [0088] The DRAM 2 , flash memory (FLASH) 3 , and clock oscillator 4 draw power from the power controller 180 in the semiconductor integrated circuit 1 . At the same time, the power controller 180 is connected with the super capacitor 5 to maintain the power PW 1 to PW 4 for a predetermined period of time after a power failure. Thus, for example, when the sample-and-hold apparatus is used as an in-car accident recorder or the like, even in incidences wherein a trigger occurs as a result of an accident shutting down the power VDD, the DRAM 2 , flash memory (FLASH) 3 , and clock oscillator 4 can keep operating normally, which ensures that scheduled sample-and-hold operations are carried out in a reliable manner. [0089] Moreover, the semiconductor integrated circuit 1 contains the control CPU 120 with a built-in microprocessor, allowing communications with a PC. This makes it possible for various settings such as switching between input ports (P 11 and P 12 ), setting a data bit count, configuring storage areas, and other settings easily from the PC, resulting in an extremely versatile semiconductor integrated circuit. [0090] In particular, as shown in FIG. 3 , this embodiment is provided with the port P 6 which is inputted with control data and with the control CPU 120 which serves as area definition data generating means for internally generating area definition data based on the control data inputted through the port P 6 . This makes it possible to set up appropriate storage areas according to various sampling data by inputting appropriate control data to the port P 6 from outside. [0091] Specifically, by setting the control data from outside to contain both data indicating the capacity of the first storage area and data indicating the capacity of the second storage area, and by setting the area definition data generating means to generate area definition data based on the two sets of data (Step 303 : “both intervals”), it is possible to set the first storage area and second storage area individually to any desired capacity by providing control data from outside. Alternatively, by setting the control data from outside to contain data indicating the capacity of the first storage area, but not data indicating the capacity of the second storage area, and by setting the area definition data generating means to generate area definition data based only on the data indicating the capacity of the first storage area (Step 303 : “preceding interval”), it is possible to set the capacity of the first storage area and capacity of the second storage area properly by simply supplying control data which represents only the capacity of the first storage area, provided that an appropriate correlation between the capacity of the first storage area and capacity of the second storage area is defined in advance. Regarding the unit used to specify the intervals, since “time duration” and “data quantity” can be used selectively, the appropriate unit can be selected according to the kind of data to be analyzed. [0092] Regarding the capacities of the first storage area 401 and second storage area 402 relative to each other in FIG. 4 , preferably the storage capacity of the first storage area 401 is an integral multiple of the storage capacity of the second storage area 402 (more preferably the former is twice the latter). This will make it easy to collate the data stored in the first storage area and data stored in the second storage area in units of data strings when image data or voice data divided into frames are handled if the capacity of the second storage area is related to the size of the frame in advance. [0093] Finally, description will be given to some concrete application examples of a sample-and-hold IC according to the present invention. FIG. 8 shows a block diagram of a data recorder to which the sample-and-hold IC according to the present invention is applied. In the figure, reference numeral 801 denotes a probe which detects feature values of a measured object such as voltage, temperature, pressure, and flow rate; 802 denotes an input circuit which generates electrical signals corresponding to the feature values based on signals obtained from the probe; 803 denotes an AD/I2S conversion circuit which converts analog signals obtained from the input circuit into digital signals and transmits the digital signals to an I2S bus; 804 denotes the sample-and-hold IC according to the present invention; 805 denotes a DRAM which functions as a primary storage medium; 806 denotes a flash memory which similarly functions as a secondary storage medium; 807 denotes an I2S/USB conversion circuit which receives sample-and-hold data transmitted from the sample-and-hold IC 804 to the I2S bus and transmits the sample-and-hold data out to a USB bus; 808 denotes a personal computer which receives and processes the sample-and-hold data; and 809 denotes a trigger generation circuit which generates a trigger signal TRG when various status signals S 1 to Sk (e.g., signals which represent temperature, pressure, sound volume, vibration, etc. around an object to be detected) satisfy predetermined conditions. [0094] In this application example, the feature data detected by the probe 801 is constantly stored in a first storage area of the DRAM 805 using wrap-around addressing. When the status signals S 1 to Sk satisfy the predetermined conditions, a trigger signal TRG is generated by the trigger generation circuit 809 and supplied to the sample-and-hold IC. Consequently, series of incoming feature data is written into a second storage area instead of the first storage area. Then, the data strings stored in the first and second storage areas are transferred to the flash memory 806 which is a secondary storage medium. Then, the data strings stored in the flash memory 806 (the data strings in predetermined intervals before and after the arrival time of the trigger signal) are read out and loaded onto the personal computer 808 . If such a data recorder is installed in a car, by recording car speed, accelerator opening, engine conditions, brake conditions, and the like with an appropriate probe and generating a trigger signal using an airbag activation signal which is highly correlated with a car accident, it is possible to save valuable data at the time of an accident. [0095] FIG. 9 shows a block diagram of a monitoring device to which the sample-and-hold IC according to the present invention is applied. In the figure, reference numeral 901 denotes a camera which includes a photographic lens and image sensor; 902 denotes a signal processing circuit which processes video signals from the camera; 903 denotes a compression/decompression circuit (codec) which compresses signals from the signal processing circuit; 904 denotes a DATA/I2S conversion circuit which transmits the data obtained from the compression/decompression circuit to an I2S bus; 905 denotes the sample-and-hold IC according to the present invention; 906 denotes a DRAM which functions as a primary storage medium; 907 denotes a flash memory which similarly functions as a secondary storage medium; 908 denotes an I2S/USB conversion circuit which receives sample-and-hold data transmitted from the sample-and-hold IC to the I2S bus and transmits the sample-and-hold data out to a USB bus; 909 denotes a personal computer which receives and processes the sample-and-hold data; and 910 denotes a trigger generation circuit which generates a trigger signal TRG when various status signals S 1 to Sk (e.g., signals which represent temperature, pressure, sound volume, vibration, etc. around an object to be detected) satisfy predetermined conditions. In this example, status signals include a focus error signal obtained from the camera 901 , a signal from a switch 911 placed in a monitoring area and activated by an intruder, a signal from an acceleration sensor (not shown) which is contained in the camera and detects the movement of the camera itself, a signal from a microphone (not shown) which gathers sounds in the monitoring area, and the video signals from the camera themselves. [0096] In this application example, the image data acquired by the camera 901 is normally stored in a first storage area of the DRAM 906 using wrap-around addressing. If the status signals S 1 to Sk satisfy the predetermined conditions caused by entry of an intruder in the monitoring area, a trigger signal TRG is generated by the trigger generation circuit 910 and supplied to the sample-and-hold IC 905 . Consequently, series of incoming image data is written into a second storage area instead of the first storage area. Then, the image data strings stored in the first and second storage areas are transferred to the flash memory 907 which is a secondary storage medium. Then, the image data strings stored in the flash memory 907 (the image data strings in predetermined intervals before and after the arrival time of the trigger signal) are read out and loaded onto the personal computer 909 . If such a monitoring device is applied to a security monitoring system at the door, when an intruder appears in front of the door, it is possible to save a series of images including the behavior of the intruder up to that time.

To provide a sample-and-hold method which can limit the storage capacity of storage media needed to a bare minimum and can independently manage a series of data contained in a predetermined interval before the arrival time of a trigger signal and a series of data contained in a predetermined interval after the arrival time of the trigger signal by separating them clearly. The present invention comprises a primary storage medium; an area definition data storage means for storing area definition data that defines a first storage area which corresponds to the interval before the arrival time and a second storage area which corresponds to the interval after the arrival time in the primary storage medium; a first write control means for continuing to write a series of incoming data into the first storage area defined by the area definition data, using wrap around addressing until the trigger signal arrives; and a second write control means for writing a series of data arriving after the arrival of the trigger signal into the second storage area defined by the area definition data instead of ceasing to write data into the first storage area when the trigger signal arrives.

CROSS REFERENCE TO RELATED APPLICATION The present U.S. Utility Patent Application claims priority under 35 U.S.C. §120, as a continuation of U.S. Utility patent application Ser. No. 12/537,495, filed Aug. 7, 2009, issuing as U.S. Pat. No. 8,275,423, which is incorporated herein by reference in its entirety for all purposes. The Ser. No. 12/537,495 application claims priority under 35 U.S.C. §120, as a continuation of U.S. Utility patent application Ser. No. 10/810,094, filed Mar. 26, 2004, now U.S. Pat. No. 7,583,985, which is incorporated herein by reference in its entirety for all purposes. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to the field of data processing. In one aspect, the present invention relates to a method and system for reducing power consumption in a communications system. 2. Related Art In general, data processors are capable of executing a variety of instructions. Processors are used in a variety of applications, including communication systems formed with wireless and/or wire-lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital amps, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS) and/or variations thereof. Especially with wireless and/or mobile communication devices (such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc.), the processor or processors in a device must be able to run various complex communication programs using only a limited amount of power that is provided by power supplies, such as batteries, contained within such devices. In particular, for a wireless communication device to participate in wireless communications, the device includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). To implement the transceiver function, one or more processors and other modules are used to form a transmitter which typically includes a data modulation stage, one or more intermediate frequency stages and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. Alternatively, in direct conversion transmitters/receivers, conversion directly between baseband signals and RF signals is performed. The power amplifier amplifies the RF signals prior to transmission via an antenna. In addition, one or more processors and other modules are used to form a receiver which is typically coupled to an antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard. Because of the computational intensity (and the associated power consumption by the processor(s)) for such transceiver functions, it is an important goal in the design of wireless and/or mobile communication devices to minimize processor and other module operations (and the associated power consumption). It is particularly crucial for mobile applications in order to extend battery life. The device must provide a high rate of data throughput when necessary, and otherwise enter a low power mode, called a sleep mode, where various modules are deactivated. Such a strategy can greatly decrease the system's average power consumption. With conventional solutions for saving power, a variety of complex circuit and hardware designs have been proposed. These mechanisms exhibit substantial latencies for entering and leaving sleep mode, which restricts the power that can be saved and the range of applicability because these latencies may preclude a processor from being able to deactivate modules before having to reactivate them. Moreover, these mechanisms are burdensome to use, requiring code routines such as an interrupt handler to evaluate and respond to the wake-up conditions. In addition, many implementations are based on complex signaling mechanisms and processor state transitions which require significant hardware and software support and also exhibit long latencies. In addition to the complexity of the computational requirements for a communications transceiver, such as described above, the ever-increasing need for higher speed communications systems imposes additional performance requirements and resulting costs for communications systems. In order to reduce costs, communications systems are increasingly implemented using Very Large Scale Integration (VLSI) techniques. The level of integration of communications systems is constantly increasing to take advantage of advances in integrated circuit manufacturing technology and the resulting cost reductions. This means that communications systems of higher and higher complexity are being implemented in a smaller and smaller number of integrated circuits. For reasons of cost and density of integration, the preferred technology is CMOS. To this end, digital signal processing (“DSP”) techniques generally allow higher levels of complexity and easier scaling to finer geometry technologies than analog techniques, as well as superior testability and manufacturability. Therefore, a need exists for a method and apparatus that provides reduced power consumption with smaller deactivation and/or activation latencies. In addition, a need exists for reducing processor power consumption without requiring complex hardware and elaborate signaling mechanisms. Moreover, a need exists for improved selectivity when determining the nature and extent of the required power-up operations. There is also a need for a better system that is capable of performing the above functions and overcoming these difficulties without increasing circuit area and operational power. Further limitations and disadvantages of conventional systems will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow. SUMMARY OF THE INVENTION The present invention is directed to apparatus and methods of operation that are further described in the following Brief Description of the Drawings, the Detailed Description of the Invention, and the Claims. Other features and advantages of the present invention will become apparent from the following detailed description of the embodiments of the invention made with reference to the accompanying claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a wireless communication system in accordance with an exemplary embodiment of the present invention. FIG. 2 is a schematic block diagram of a wireless communication device in accordance with an exemplary embodiment of the present invention. FIG. 3 is a schematic block diagram of a wireless interface device in accordance with an exemplary embodiment of the present invention. FIG. 4 depicts an exemplary state machine description of an exemplary embodiment of the present invention. FIG. 5 depicts a methodology and program sequence for an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION A method and apparatus for an improved communications processor is described. While various details are set forth in the following description, it will be appreciated that the present invention may be practiced without these specific details. For example, selected aspects are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention. Some portions of the detailed descriptions provided herein are presented in terms of algorithms or operations on data within a computer memory. Such descriptions and representations are used by those skilled in the data processing arts to describe and convey the substance of their work to others skilled in the art. In general, an algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may, though need not necessarily, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions using terms such as processing, computing, calculating, determining, displaying or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and/or transforms data represented as physical, electronic and/or magnetic quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. Broadly speaking, the present invention provides an improved method and system for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and the required modules necessary to respond to the asserted wake-up conditions. This may be accomplished by issuing a wake-up signal only when specified wake-up conditions are detected, and then only reactivating the necessary components to respond to the wake-up signal. With this approach, a staged wake-up is provided for improved power management with reduced latencies. In accordance with various embodiments of the present invention, a method and apparatus provides a power saving mechanism for a programmable communications processor. The power saving mechanism may be implemented using the MAC layer programming to control the sleep and wake-up modes and to provide for a staged wake-up of various processor modules for improved power management. The host processor may also be subject to this power management. The PSM invokes the power saving mechanism by specifying wake-up conditions and a sleep time-out period, and then executing a sleep instruction until a wake-up condition is detected or the time-out period expires, at which time the wake-up condition is processed to determine what specific circuitry or modules need to be reactivated. In a selected embodiment power control logic is provided for directly awakening some modules, while other modules are awakened by the PSM's instruction once the PSM reawakens. Thus, the present invention provides improved effectiveness, reduced latency, simplified programming and reduced hardware overhead. FIG. 1 illustrates a wireless communication system 10 in which embodiments of the present invention may operate. As illustrated, the wireless communication system 10 includes a plurality of base stations and/or access points 12 , 16 , a plurality of wireless communication devices 18 - 32 and a network hardware component 34 . The wireless communication devices 18 - 32 may be laptop host computers 18 , 26 , personal digital assistant hosts 20 , 30 , personal computer hosts 32 , cellular telephone hosts 28 and/or wireless keyboards, mouse devices or other Bluetooth devices 22 , 24 . The details of the wireless communication devices will be described in greater detail with reference to FIGS. 2-5 . As illustrated, the base stations or access points 12 , 16 are operably coupled to the network hardware 34 via local area network connections 36 , 38 . The network hardware 34 (which may be a router, switch, bridge, modem, system controller, etc.) provides a wide area network connection 42 for the communication system 10 . Each of the base stations or access points 12 , 16 has an associated antenna or antenna array to communicate with the wireless communication devices in its area. Typically, the wireless communication devices register with a particular base station or access point 12 , 16 to receive services from the communication system 10 . For direct connections (e.g., point-to-point communications between laptop 26 and mouse or keyboard 22 ), wireless communication devices communicate directly via an allocated channel. Regardless of the particular type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. The radio includes a highly linear amplifier and/or programmable multi-stage amplifier with a low latency power saving mechanism as disclosed herein to enhance performance, reduce costs, reduce size, reduce power consumption and/or enhance broadband applications. FIG. 2 is a schematic block diagram illustrating a radio implemented in a wireless communication device that includes the host device or module 50 and at least one wireless interface device, or radio transceiver 59 . The wireless interface device may be built in components of the host device 50 or externally coupled components. As illustrated, the host device 50 includes a processing module 51 , memory 52 , peripheral interface 55 , input interface 58 and output interface 56 . The processing module 51 and memory 52 execute the corresponding instructions that are typically done by the host device. For example, in a cellular telephone device, the processing module 51 performs the corresponding communication functions in accordance with a particular cellular telephone standard. The wireless interface device 59 includes a host interface, a media-specific access control protocol (MAC) layer module, a physical layer module (PHY), a digital-to-analog converter (DAC), and an analog to digital converter (ADC). The peripheral interface 55 allows data to be received from and sent to one or more external devices 65 via the wireless interface device 59 . As will be appreciated, the modules in the wireless interface device are implemented with a communications processor and an associated memory for storing and executing instructions that control the access to the physical transmission medium in the wireless network. Each external device includes its own wireless interface device for communicating with the wireless interface device of the host device. For example, the host device may be personal or laptop computer and the external device 65 may be a headset, personal digital assistant, cellular telephone, printer, fax machine, joystick, keyboard, desktop telephone, or access point of a wireless local area network. In this example, external device 65 is an IEEE 802.11 wireless interface device. FIG. 3 is a schematic block diagram of a wireless interface device (i.e., a radio) 60 which includes a host interface 62 , digital receiver processing module 64 , an analog-to-digital converter (ADC) 66 , a filtering/gain module 68 , a down-conversion stage 70 , a receiver filter 71 , a low noise amplifier 72 , a transmitter/receiver switch 73 , a local oscillation module 74 , memory 75 , a digital transmitter processing module 76 , a digital-to-analog converter (DAC) 78 , a filtering/gain module 80 , a mixing up-conversion stage 82 , a power amplifier 84 , and a transmitter filter module 85 . The transmitter/receiver switch 73 is coupled to the antenna 87 , which may include two antennas coupled through a switch. Still further, the antenna section 61 may include separate multiple antennas 87 a , 87 b for the transmit path and the receive path of each wireless interface device (as shown in FIG. 3 ). As will be appreciated, the antenna(s) may be polarized, directional, and be physically separated to provide a minimal amount of interference. The digital receiver processing module 64 , the digital transmitter processing module 76 and the memory 75 may execute digital receiver functions and digital transmitter functions in accordance with a particular wireless communication standard. The digital receiver functions include, but are not limited to, digital frequency conversion, demodulation, constellation demapping, decoding and/or descrambling. The digital transmitter functions include, but are not limited to, scrambling, encoding, constellation mapping, modulation and/or digital frequency conversion. The digital receiver and transmitter processing modules 64 , 76 may be implemented using a shared processing device, individual processing devices, or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory 75 may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module 64 , 76 implements one or more of its functions via a state machine, analog circuitry, digital circuitry and/or logic circuitry, the memory storing the corresponding operational instructions may be embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry and/or logic circuitry. In operation, the wireless interface device 60 receives outbound data 94 from the host device via the host interface 62 . The host interface 62 routes the outbound data 94 to the digital transmitter processing module 76 , which processes the outbound data 94 to produce digital transmission formatted data 96 in accordance with a particular wireless communication standard, such as IEEE 802.11 (including all current and future subsections), Bluetooth, etc. The digital transmission formatted data 96 will be a digital base-band signal or a digital low IF signal, where the low IF typically will be in the frequency range of one hundred kilohertz to a few megahertz. Subsequent stages convert the digital transmission formatted data to an RF signal, and may be implemented as follows. The digital-to-analog converter 78 converts the digital transmission formatted data 96 from the digital domain to the analog domain. The filtering/gain module 80 filters and/or adjusts the gain of the analog signal prior to providing it to the up-conversion module 82 . The mixing stage 82 directly converts the analog baseband or low IF signal into an RF signal based on a transmitter local oscillation clock 83 provided by local oscillation module 74 . The power amplifier 84 amplifies the RF signal to produce outbound RF signal 98 , which is filtered by the transmitter filter module 85 . The antenna section 61 transmits the outbound RF signal 98 to a targeted device such as a base station, an access point and/or another wireless communication device. The wireless interface device 60 also receives an inbound RF signal 88 via the antenna section 61 , which was transmitted by a base station, an access point, or another wireless communication device. The inbound RF signal is converted into digital reception formatted data; this conversion may be implemented as follows. The antenna section 61 provides the inbound RF signal 88 to the receiver filter module 71 via the transmit/receive switch 73 , where the receiver filter 71 bandpass filters the inbound RF signal 88 . The receiver filter 71 provides the filtered RF signal to low noise amplifier 72 , which amplifies the signal 88 to produce an amplified inbound RF signal. The low noise amplifier 72 provides the amplified inbound RF signal to the mixing module 70 , which directly converts the amplified inbound RF signal into an inbound low IF signal or baseband signal based on a receiver local oscillation clock 81 provided by local oscillation module 74 . The down conversion module 70 provides the inbound low IF signal or baseband signal to the filtering/gain module 68 . The filtering/gain module 68 filters and/or gains the inbound low IF signal or the inbound baseband signal to produce a filtered inbound signal. The analog-to-digital converter 66 converts the filtered inbound signal from the analog domain to the digital domain to produce digital reception formatted data 90 . The digital receiver processing module 64 decodes, descrambles, demaps, and/or demodulates the digital reception formatted data 90 to recapture inbound data 92 in accordance with the particular wireless communication standard being implemented by wireless interface device. The host interface 62 provides the recaptured inbound data 92 to the host device (e.g., 50 ) via the peripheral interface (e.g., 55 ). As will be appreciated, the wireless communication device of FIG. 2 described herein may be implemented using one or more integrated circuits. For example, the host device 50 may be implemented on one integrated circuit, the digital receiver processing module 64 , the digital transmitter processing module 76 and memory 75 may be implemented on a second integrated circuit, and the remaining components of the wireless interface device 60 and/or antenna 61 , may be implemented on a third integrated circuit. As an alternate example, the wireless interface device 60 may be implemented on a single integrated circuit. As yet another example, the processing module 51 of the host device and the digital receiver and transmitter processing modules 64 and 76 may be a common processing device implemented on a single integrated circuit. Further, the memory 52 and memory 75 may be implemented on a single integrated circuit and/or on the same integrated circuit as the common processing modules of processing module 51 and the digital receiver and transmitter processing module 64 and 76 . In a selected embodiment, the present invention shows, for the first time, a fully integrated, single chip 802.11b/g solution with built-in power management that reduces power consumption using an intelligent stand-by mode to provide greatly extended battery life for mobile devices, all implemented in CMOS (Complementary Metal Oxide Semiconductor), as part of a single chip or multi-chip transceiver radio. As for the processor componentry of the wireless interface device or radio, an exemplary depiction of the processor details is illustrated in FIG. 3 as communication processor 100 , which shows a system level description of the operation of an embodiment of a communication processor embodiment of the present invention. The communication processor 100 may be an integrated circuit or it may be constructed from discrete components. The communication processor 100 may implement a MAC module using a programmable state machine 102 (which includes the Fetch 141 , Decode 143 , Read 145 , Execute 147 and Write 149 pipeline, in that order). The processor 100 also includes a memory 118 , which may be implemented as a data RAM memory and code EPROM memory. Also included in the processor are the transmit/receive queues and supporting hardware 182 (coupled between host interface 181 and PHY interface 183 ), which may include transmit and receive queues, encryption modules, transmit and receive engines and/or packet processing hardware. For power management of the processor 100 , power-management logic 172 is provided, including the wake-up timer 134 , logic to select wake-up conditions, and logic to direct modules to deactivate themselves. To reduce the power consumed by processor-related circuits, the present invention provides a power management scheme to extend the battery life of Wi-Fi enabled small mobile devices. In a selected embodiment, the power management scheme uses a software approach to place the transceiver in standby mode and to selectively respond to wake-up commands, thereby reducing power consumption significantly without imposing a performance cost. In mobile device applications, the communications processor is able to spend a majority of its time in standby mode, adding several days of battery life to a PDA. In a selected embodiment illustrated in FIG. 3 , power management may be implemented using a wake-up timer 134 and a one or more specified wake-up conditions. The processor 100 may include instruction decode logic and branch condition logic that is configured to detect a sleep instruction and to respond to the wake-up conditions or the timer 134 . Once the communications processor 100 completes a high throughput task and/or receives a sleep instruction, the processor 100 prepares to enter sleep mode by specifying a set of conditions that will re-awaken it. The processor 100 then deactivates as many modules as possible. Some deactivations may occur prior to executing the sleep instruction. Once the sleep instruction has entered the instruction pipeline 140 and the preceding instructions in the pipeline have been completed, the remaining nonessential modules (such as the transmit/receive queues and major portions of the programmable state machine, etc.) are powered-down by either freezing their clocks or placing them in an idle mode. When one of the specified conditions is detected, the processor wakes up, analyzes the condition, and reactivates whatever modules are needed to service the condition. As illustrated in FIG. 4 , the sleep and wake-up modes described herein may be controlled by a programmable state machine (PSM) in the MAC layer of a communications processor, whereby the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications or host related event. In particular, a processor that is fully or partially active and executing instructions (state 402 ) executes a power management program (transition 403 ) which specifies the wake-up conditions to which it will respond, along with a time-out period, any one of which will be used to generate a wake-up signal (state 404 ). The processor subsequently receives a sleep instruction (transition 405 ) and changes to a power down state 406 . In the power down state 406 , the processor and some associated modules are also placed in a sleep mode by disabling power and/or clock signals to the processor modules or otherwise idling the modules. Upon receipt of a wake-up signal (transition 407 ), a selective reactivation state is entered (state 408 ), whereby the required processor componentry and/or modules are powered-up based upon the detected wake-up condition. The processor then begins processing the wake-up signal and its associated wake-up condition(s) to proceed (via transition 409 ) to the fully or partially active instruction execution state (state 402 ), where the required modules are used to execute the instruction(s) corresponding to the detected wake-up condition. In a selected embodiment, when the PSM wakes up, all of the instruction pipeline stages also wake up to permit the instruction to flow from stage to stage, progressing through fetch/decode, read, execute, and write. FIG. 5 depicts an exemplary power saving methodology and program sequence for the present invention. As an initial step, after having completed any previous communication tasks, the processor 100 specifies the wake-up conditions that will be used to wake up the processor, along with a time-out period, at step 502 . For example, the conditions to observe and the wake-up interval may be specified by registers which are loaded by a power saving program. The processor may then deactivate certain nonessential modules, at step 503 . In a selected embodiment, these modules are those whose deactivation is controlled by the processor's instructions. With step 503 , the PSM's instructions power down some modules (generally by writing appropriate values into the modules' control registers) prior to the PSM's execution of the sleep instruction. The processor detects and executes a sleep instruction at step 504 . This sleep instruction detection functionality may be implemented by control logic in the processor 100 . In one implementation, the instruction decode logic in the processor 100 may be extended to detect the sleep instruction (step 504 ). Upon receipt of a sleep instruction, the processor logic determines that preceding instructions in the pipeline 140 have completed (step 506 ) prior to deactivation. Upon completion of the pending instructions from the pipeline, the processor and its associated modules enter a sleep or standby mode at step 508 . In a selected embodiment, if a sleep instruction is encountered (decision 504 ) when the specified wake-up conditions are deasserted, the control logic will cease fetching new instructions, wait until any preceding instructions are finished (step 506 ), and then cause the processor to enter a dormant, low-power state (step 508 ). The low-power state may be implemented by disabling the clocks for one or more processor modules. In a selected embodiment, these modules are those whose deactivation is directly controlled by the processor's hardware. For any processor modules which require clocks in order to provide data for external devices, these modules may be directed to enter an idle mode. Once the processor is powered down or in standby mode, when one of the specified conditions occurs or if the wake-up interval is reached (detection step 510 ), the wake-up signal asserts. In a selected implementation, branch condition logic in the processor may be expanded to select multiple conditions and logically OR them together—along with the wake-up timer's output—to form a wake-up signal. At step 512 , the wake-up signal is issued to the processor. In a selected embodiment, the wake-up signal is supplied to the control logic which reactivates instruction pipeline 140 to begin fetching the next instruction after the sleep instruction (step 514 ). Subsequent stages of the pipeline are reactivated as this instruction and those that follow are processed. At step 516 , the instructions following the sleep instruction are executed by processor 100 to analyze the asserted wake-up conditions and reactivate the modules that are needed to respond to the wake-up condition (step 518 ). Rather than reactivating the entire processor and associated modules, the present invention allows for judicious use of power upon wake-up by reactivating only the modules that are needed to service the wake-up condition. Upon completing the required communications tasks, the processor may then specify another set of wake-up conditions and a time-out interval, prior to executing an associated sleep instruction. Optionally, the processor may loop back and repeat some or all of the outlined procedure using the specified wake-up conditions and time-out interval. With the power saving mechanism of the present invention, the deactivation and re-activation latencies may be reduced significantly as compared to conventional hardware-based techniques involving an interrupt handler to facilitate these tasks. Such conventional techniques require elaborate signaling mechanisms and processor state transitions that impose long latencies. Such latencies greatly restrict the amount of power that can be saved as well as the range of situations where modules can be powered-down. In contrast, an implementation of the present invention relies on a sleep instruction along with logic to decode it and respond appropriately, including selection of wake-up signals and a time-out interval, which quickly and efficiently enables selective reactivation of only the processor modules that are required to service the specified wake-up condition, thereby applying only power that is needed to service the wake-up conditions. In particular, effective power saving is obtained by deactivating all instruction pipeline stages (instruction fetch, instruction decode and operand read, execution, and write) and other external modules, and then selectively reactivating only the modules needed to service the wake-up condition. A power saving program embodiment provides low latency standby mode to reduce power consumption with minimum delay, and allows its application to a wide range of situations, including those where high throughput and idle intervals alternate in close proximity. From the programmer's perspective, the power saving mechanism of the present invention is simple to use, requiring specification of wake-up conditions and a wake-up interval and then a single sleep instruction. Little additional program memory is needed for these instructions. From a hardware perspective, the overhead is relatively low with only minor extensions being needed with regard to the instruction decode and branch condition logic, as well as the addition of a count-down timer. As described herein and claimed below, a method and apparatus are provided for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications event. This translates to a very power efficient processor. As will be appreciated, the present invention may be implemented in a computer accessible medium including one or more data structures representative of the circuitry included in the system described herein. Generally speaking, a computer accessible medium may include storage media such as magnetic or optical media, e.g., disk, CD-ROM, or DVD-ROM, volatile or non-volatile memory media such as RAM (e.g., SDRAM, RDRAM, SRAM, etc.), ROM, PROM, EPROM, EEPROM, etc. For example, data structure(s) of the circuitry on the computer accessible medium may be read by a program and used, directly or indirectly, to implement the hardware comprising the circuitry described herein. For example, the data structure(s) may include one or more behavioral-level descriptions or register-transfer level (RTL) descriptions of the hardware functionality in a high level design language (HDL) such as Verilog or VHDL. The description(s) may be read by a synthesis tool which may synthesize the description to produce one or more netlist(s) comprising lists of gates from a synthesis library. The netlist(s) comprise a set of gates which also represent the functionality of the hardware comprising the circuitry. The netlist(s) may then be placed and routed to produce one or more data set(s) describing geometric shapes to be applied to masks. The masks may then be used in various semiconductor fabrication steps to produce a semiconductor circuit or circuits corresponding to the circuitry. Alternatively, the data structure(s) on computer accessible medium may be the netlist(s) (with or without the synthesis library) or the data set(s), as desired. In yet another alternative, the data structures may comprise the output of a schematic program, or netlist(s) or data set(s) derived therefrom. While a computer accessible medium may include a representation of the present invention, other embodiments may include a representation of any portion of the power management system and/or the PSM, memory, supporting hardware modules and power-down logic. While the system and method of the present invention has been described in connection with the preferred embodiment, it is not intended to limit the invention to the particular form set forth, but on the contrary, is intended to cover such alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims so that those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention in its broadest form.

A power management scheme for a wireless communications device processor substantially implemented on a single CMOS integrated circuit is described. By incorporating controls for sleep and wake-up mode transitions in the processor's control logic, improved power savings with reduced latency is provided, obviating the need for hardware-focused solutions with elaborate signaling mechanisms. A fully integrated power management with staged wake-up operations controlled by the MAC solution consumes less power than the conventional wireless LAN solutions in standby mode.

CROSS-REFERENCE TO PRIOR PROVISIONAL APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60/093,421, filed Jul. 20, 1998 BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a fluidic medical diagnostic device for measuring the concentration of an analyte in or a property of a biological fluid. [0004] 2. Description of the Related Art [0005] A variety of medical diagnostic procedures involve tests on biological fluids, such as blood, urine, or saliva, and are based on a change in a physical characteristic of such a fluid or an element of the fluid, such as blood serum. The characteristic can be an electrical, magnetic, fluidic, or optical property. When as optical property is monitored, these procedures may make use of a transparent or translucent device to contain the biological fluid and a reagent. A change in light absorption of the fluid can be related to an analyte concentration in, or property of, the fluid. Typically, a light source is located adjacent to one surface of the device and a detector is adjacent to the opposite surface. The detector measures light transmitted through a fluid sample. Alternatively, the light source and detector can be on the same side of the device, in which case the detector measures light scattered and/or reflected by the sample. Finally, a reflector may be located at or adjacent to the opposite surface. A device of this latter type, in which light is first transmitted through the sample area, then reflected through a second time, is called a “transflectance” device. References to “light” throughout this specification and the appended claims should be understood to include the infrared and ultraviolet spectra, as well as the visible. References to “absorption” are meant to refer to the reduction in intensity as a light beam passes through a medium; thus, it encompasses both “true” absorption and scattering. [0006] An example of a transparent test device is described in Wells et al. WO94/02850, published on Feb. 3, 1994. Their device comprises a sealed housing, which is transparent or translucent, impervious, and rigid or semi-rigid. An assay material is contained within the housing, together with one or more assay reagents at predetermined sites. The housing is opened and the sample introduced just before conducting the assay. The combination of assay reagents and analyte in the sample results in a change in optical properties, such as color, of selected reagents at the end of the assay. The results can be read visually or with an optical instrument. [0007] U.S. Pat. No. 3,620,676, issued on Nov. 16, 1971 to Davis, discloses a calorimetric indicator for liquids. The indicator includes a “half-bulb cavity”; which is compressible. The bulb is compressed and released to form a suction that draws fluid from a source, through a half-tubular cavity that has an indicator imprinted on its wall. The only controls on fluid flow into the indicator are how much the bulb is compressed and how long the indicator inlet is immersed in the source, while the bulb is released. [0008] U.S. Pat. No. 3,640,267, issued on Feb. 8, 1972 to Hurtig et al., discloses a container for collecting Kilo samples of body fluid that includes a chamber that has resilient, collapsible walls. The walls are squeezed before the container inlet is placed into the fluid being collected. When released, the walls are restored to their uncollapsed condition, drawing fluid into and through the inlet. As with the Davis device, discussed above, control of fluid flow into the indicator is very limited. [0009] U.S. Pat. No. 4,088,448, issued on May 9, 1978 to Lilja et al., discloses a cuvette, which permits optical analysis of a sample mixed with a reagent. The-reagent is coated on the walls of a cavity, which is then filled with a liquid sample. The sample mixes with the reagent to cause an optically-detectable change. [0010] A number of patents, discussed below, disclose devices for diluting and/or analyzing biological fluid samples. These devices include valve-like designs to control the flow of the sample. [0011] U.S. Pat. No. 4,426,451, issued on Jan. 17, 1984 to Columbus, discloses a multi-zone fluidic device that has pressure-actuatable means for controlling the flow of fluid between the zones. His device makes use of pressure balances on a liquid meniscus at the interface between a first zone and a second zone that has a different cross section. When both the first and second zones are at atmospheric pressure, surface tension creates a back pressure that stops the liquid meniscus from proceeding from the first zone to the second. The configuration of this interface or “stop junction” is such that the liquid flows into the second zone only upon application of an externally generated pressure to the liquid in the first zone that is sufficient to push the meniscus into the second zone. [0012] U.S. Pat. No. 4,868,129, issued on Sep. 19, 1989 to Gibbons et al., discloses that the back pressure in a stop junction can be overcome by hydrostatic pressure on the liquid in the first zone, for example by having a column of fluid in the first zone. [0013] U.S. Pat. No. 5,230,866, issued on Jul. 27, 1993 to Shartle et al., discloses a fluidic device with multiple stop junctions in which the surface tension-induced back pressure at the stop junction is augmented; for example, by trapping and compressing gas in the second zone. The compressed gas can then be vented before applying additional hydrostatic pressure to the first zone to cause fluid to flow into the second zone. By varying the back pressure of multiple stop junctions in parallel, “rupture junctions” can be formed, having lower maximum back pressure. [0014] U.S. Pat. No. 5,472,603, issued on Dec. 5, 1995 to Schembri (see also U.S. Pat. No. 5,627,041), discloses using centrifugal force to overcome the back pressure in a stop junction. When flow stops, the first zone is at atmospheric pressure plus a centrifugally generated pressure that is less than the pressure required to overcome the back pressure. The second zone is at atmospheric pressure. To resume flow, additional centrifugal pressure is applied to the first zone, overcoming the meniscus back pressure. The second zone remains at atmospheric pressure. [0015] European Patent Application EP 0,803,288, of Naka et al., published on Oct. 29, 1997, discloses a device and method for analyzing a sample that includes drawing the sample into the device by suction, then reacting the sample with a reagent in an analytical section. Analysis is done by optical or electrochemical means. In alternate embodiments, there are multiple analytical sections and/or a bypass channel. The flow among these sections is balanced without using stop junctions. [0016] U.S. Pat. No. 5,700,695, issued on Dec. 23, 1997 to Yassinzadeh et al., discloses an apparatus for collecting and manipulating a biological fluid that uses a “thermal pressure chamber” to provide the driving force for moving the sample through the apparatus. [0017] U.S. Pat. No. 5,736,404, issued on Apr. 7, 1998, to Yassinzadeh et al., discloses a method for determining the coagulation time of a blood sample that involves causing an end of the sample to oscillate within a passageway. The oscillating motion is caused by alternately increasing and decreasing the pressure on the sample. SUMMARY OF THE INVENTION [0018] The present invention provides a fluidic diagnostic device for measuring an analyte concentration or property of a biological fluid. The device comprises a first layer and second layer at least one of which has a resilient region over at least part of its area, separated by an intermediate layer, in which cutouts in the intermediate layer form, with the first and second layers, [0019] a) a sample port for introducing a sample of the biological fluid into the device; [0020] b) a first measurement area, in which a physical parameter of the sample is measured and related to the analyte concentration or property of the fluid; [0021] c) a first channel, having a first end and a second end, to provide a fluidic path from the sample port at the first end through the first measurement area; [0022] d) a first bladder at the second end of the first channel, comprising at least a part of the resilient region in at least the first or second layer and having a volume that is at least about equal to the combined volume of the first measurement area and first channel; and [0023] e) a first stop junction in the first channel between the first measurement area and first bladder that comprises a co-aligned through hole in at least the first or second layer, the through hole being overlaid with a third layer. [0024] In another embodiment, the device comprises [0025] a first layer, which has a resilient region over at least a part of its area, and a second layer, separated by an intermediate layer, in which recesses in a first surface of the intermediate layer form, with the first layer, [0026] a) a sample port for introducing a sample of the biological fluid into the device; [0027] b) a measurement area, in which the sample undergoes a change in a physical parameter that is measured and related to the analyte concentration or property of the fluid; [0028] c) a channel, having a first end and a second end, to provide a fluidic path from the sample port at the first end through the measurement area; and [0029] d) a bladder, at the second end of the channel, comprising at least a part of the resilient region in the first layer and having a volume that is at least about equal to the combined volume of the measurement area and channel; and [0030] a stop junction in the channel between the measurement area and bladder that comprises two passages substantially normal to the first surface of the intermediate layer, each passage having a first end in fluid communication with the channel and a second end in fluid communication with a recess in a second surface of the intermediate layer, which recess provides fluid communication between the second ends of the passages. [0031] The device is particularly well adapted for measuring prothrombin time (PT time), with the biological fluid being whole blood and the measurement area having a composition that catalyzes the blood clotting cascade. BRIEF DESCRIPTION OF THE DRAWINGS [0032] [0032]FIG. 1 is a plan view of a device of the present invention. [0033] [0033]FIG. 2 is an exploded view of the device of FIG. 1. [0034] [0034]FIG. 3 is a perspective view of the device of FIG. 1. [0035] [0035]FIG. 4 is a schematic of a meter for use with a device of this invention. [0036] [0036]FIG. 4A depicts an alternative embodiment of an element of the meter of FIG. 4. [0037] [0037]FIG. 5 is a graph of data that is used to determine PT time. [0038] [0038]FIG. 6 is a plan view of an alternative embodiment of a device of this invention. [0039] [0039]FIGS. 6A, 6B, and 6 C depict a time sequence during which a sample is admitted to the device of FIG. 6. [0040] [0040]FIG. 7 is a schematic of a device having multiple measurement areas in parallel, multiple stop junctions in parallel, and a single bladder. [0041] [0041]FIG. 8 is a schematic of a device having multiple measurement areas in series, with a single stop junction, a single bladder, and a filter over the sample port. [0042] [0042]FIG. 9 is a schematic of a device having multiple measurement areas and multiple stop junctions arranged in an alternating series, as well as multiple bladders. [0043] [0043]FIG. 10 is a schematic of a device that includes multiple measurement areas in parallel, a single bladder, and a single bypass channel. [0044] [0044]FIG. 11 is a schematic of a device having multiple measurement areas in series, multiple stop junctions in series, multiple-bladders in series, and multiple bypass channels. [0045] [0045]FIG. 12 is an exploded view of an injection-molded device of this invention. [0046] [0046]FIG. 13 is a perspective view of the device of FIG. 12. DETAILED DESCRIPTION OF THE INVENTION [0047] This invention relates to a fluidic device for analyzing biological fluid. The device is of the type that relates a physical parameter of the fluid, or an element of the fluid, to an analyte concentration in the fluid or to a property of the fluid. Although a variety of physical parameters—e.g., electrical, magnetic, fluidic, or optical—can form the basis for the measurement, a change in optical parameters is a preferred basis, and the details that follow refer to an optical device. The device includes a sample application area; a bladder, to create a suction force to draw the sample into the device; a measurement area, in which the sample may undergo a change in an optical parameter, such as light scattering; and a stop junction to precisely stop flow after filling the measurement area. [0048] Preferably, the device is substantially transparent over the measurement area, so that the area can be illuminated by a light source on one side and the transmitted light measured on the opposite side. The measurement on the sample may be of a parameter that is not changing, but typically the sample undergoes a change in the measurement area, and the change in transmitted light is a measure of the analyte or fluid property of interest. Alternatively, light that is scattered from a fluid sample or light that passes through the sample and is reflected back through a second time (by a reflector on that opposite side) can be detected by a detector on the same side as the light source. [0049] This type of device is suitable for a variety of analytical tests of biological fluids, such as determining biochemical or hematological characteristics, or measuring the concentration in such fluids of proteins, hormones, carbohydrates, lipids, drugs, toxins, gases, electrolytes, etc. The procedures for performing these tests have been described in the literature. Among the tests, and where they are described, are the following: [0050] (1) Chromogenic Factor XIIa Assay (and other clotting factors as well): Rand, M. D. et al., Blood, 88 , 3432 (1996). [0051] (2) Factor X Assay: Bick, R. L. Disorders of Thrombosis and Hemostasis: Clinical and Laboratory Practice. Chicago, ASCP Press, 1992. [0052] (3) DRVVT (Dilute Russells Viper Venom Test): Exner, T. et al., Blood Coag. Fibrinol., 1, 259 (1990). [0053] (4) Immunonephelometric and Immunoturbidimetric Assays for Proteins: Whicher, J. T., CRC Crit. Rev. Clin Lab Sci. 18:213 (1983). [0054] (5) TPA Assay: Mann, K. G., et al., Blood, 76, 755, (1990).; and Hartshorn, J. N. et al., Blood, 78, 833 (1991). [0055] (6) APTT (Activated Partial Thromboplastin Time Assay): Proctor, R. R. and Rapaport, S. I. Amer. J. Clin. Path, 36, 212 (1961); Brandt, J. T. and Triplett, D. A. Amer. J. Clin. Path., 76, 530 (1981); and Kelsey, P. R. Thromb. Haemost. 52, 172 (1984). [0056] (7) HbAlc Assay (Glycosylated Hemoglobin Assay): Nicol, D. J. et al., Clin. Chem. 29, 1694 (1983). [0057] (8) Total Hemoglobin: Schneck et al., Clinical Chem., 32/33, 526 (1986); and U.S. Pat. No. 4,088,448. [0058] (9) Factor Xa: Vinazzer, H., Proc. Symp. Dtsch. Ges. Klin. Chem., 203 (1977), ed. By Witt, I [0059] (10) Colorimetric Assay for Nitric Oxide: Schmidt, H. H., et al., Biochemica, 2, 22,(1995). [0060] The present device is particularly well suited for measuring blood-clotting time—“prothrombin time” or “PT time”—and details regarding such a device appear below. The modifications needed to adapt the device for applications such as those listed above require no more than routine experimentation. [0061] [0061]FIG. 1 is a plan view of a device 10 of the present invention. FIG. 2 is an exploded view and FIG. 3 a perspective view of the device. Sample is applied to sample port 12 after bladder 14 has been compressed. Clearly, the region of layer 26 and/or layer 28 that adjoins the cutout for bladder 14 must be resilient, to permit bladder 14 to be compressed. Polyester of about 0.1 mm thickness has suitable resilience and springiness. Preferably, top layer 26 has a thickness of about 0.125 mm, bottom layer 28 about 0.100 mm. When the bladder is released, suction draws sample through channel 16 to measurement area 18 , which preferably contains a reagent 20 . In order to ensure that measurement area 18 can be filled with sample, the volume of bladder 14 is preferably at least about equal to the combined volume of channel 16 and measurement area 18 . If measurement area 18 is to be illuminated from below, layer 28 must be transparent where it adjoins measurement area 18 . For a PT test, reagent 20 contains thromboplastin that is free of bulking reagents normally found in lyophilized reagents. [0062] As shown in FIGS. 1, 2, and 3 , stop junction 22 adjoins bladder 14 and measurement area 18 ; however, a continuation of channel 16 may be on either or both sides of stop junction 22 , separating the stop junction from measurement area 18 and/or bladder 14 . When the sample reaches stop junction 22 , sample flow stops. For PT measurements, it is important to stop the flow of sample as it reaches that point to permit reproducible “rouleaux formation”—the stacking of red blood cells—which is an important step in monitoring blood clotting using the present invention. The principle of operation of stop junctions is described in U.S. Pat. No. 5,230,866, incorporated herein by reference. [0063] As shown in FIG. 2, all the above elements are formed by cutouts in intermediate layer 24 , sandwiched between top layer 26 and bottom layer 28 . Preferably, layer 24 is double-sided adhesive tape. Stop junction 22 is formed by an additional cutout in layer 26 and/or 28 , aligned with the cutout in layer 24 and sealed with sealing layer 30 and/or 32 . Preferably, as shown, the stop junction comprises cutouts in both layers 26 and 28 , with sealing layers 30 and 32 . Each cutout for stop junction 22 is at as least as wide as channel 16 . Also shown in FIG. 2 is an optional filter 12 A to cover sample port 12 . The filter may separate out red blood cells from a whole blood sample and/or may contain a reagent to interact with the blood to provide additional information. A suitable filter comprises an anisotropic membrane, preferably a polysulfone membrane of the type available from Spectral Diagnostics, Inc., Toronto, Canada. Optional reflector 18 A may be on, or adjacent to, a surface of layer 26 and positioned over measurement area 18 . If the reflector is present, the device becomes a transflectance device. [0064] The method of using the strip of FIGS. 1, 2, and 3 can be understood with reference to a schematic of the elements of a meter shown in FIG. 4, which contemplates an automated meter. Alternatively, manual operation is also possible. (In that case, bladder 14 is manually depressed before sample is applied to sample port 12 , then released.) The first step the user performs is to turn on the meter, thereby energizing strip detector 40 , sample detector 42 , measurement system 44 , and optional heater 46 . The second step is to insert the strip. Preferably, the strip is not transparent over at least a part of its area, so that an inserted strip will block the illumination by LED 40 a of detector 40 b . (More preferably, the intermediate layer is formed of a non-transparent material, so that background light does not enter measurement system 44 .) Detector 40 b thereby senses that a strip has been inserted and triggers bladder actuator 48 to compress bladder 14 . A meter display 50 then directs the user to apply a sample to sample port 12 as the third and last step the user must perform to initiate the measurement sequence. The empty sample port is reflective. When a sample is introduced into the sample port, it absorbs light from LED 42 a and thereby reduces the light that is reflected to detector 42 b . That reduction in light, in turn, signals actuator 48 to release bladder 14 . The resultant suction in channel 16 draws sample through measurement area 18 to stop junction 22 . Light from LED 44 a passes through measurement area 18 , and detector 44 b monitors the light transmitted through the sample as it is clotting. When there are multiple measurement areas, measurement system 44 includes an LED/detector pair (like 44 a and 44 b ) for each measurement area. Analysis of the transmitted light as a function of time (as described below) permits a calculation of the PT time, which is displayed on the meter display 50 . Preferably, sample temperature is maintained at about 37° C. by heater 46 . [0065] As described above, the detector senses a sample in sample port 12 , simply by detecting a reduction in (specular) reflection of a light signal that is emitted by 42 a and detected by 42 b . However, that simple system cannot easily distinguish between a whole blood sample and some other liquid (e.g., blood serum) placed in the sample port in-error or, even, an object (e.g., a finger) that can approach sample port 12 and cause the system to erroneously conclude that a proper sample has been applied. To avoid this type of error, another embodiment measures diffuse reflection from the sample port. This embodiment appears in FIG. 4A, which shows detector 42 b positioned normal to the plane of strip 10 . With the arrangement shown in FIG. 4A, if a whole blood sample has been applied to sample port 12 , the signal detected by 42 b increases abruptly, because of scattering in the blood sample, then decreases, because of rouleaux formation (discussed below). The detector system 42 is thus programmed to require that type of signal before causing actuator 48 to release bladder 14 . The delay of several seconds in releasing bladder 14 does not substantially affect the readings described below [0066] [0066]FIG. 5 depicts a typical “clot signature” curve in which the current from detector 44 b is plotted as a function of time. Blood is first detected in the measurement area by 44 b at time 1 . In the time interval A, between points 1 and 2 , the blood fills the measurement area. The reduction in current during that time interval is due to light scattered by red cells and is thus an approximate measure of the hematocrit. At point 2 , sample has filled the measurement area and is at rest, its movement having been stopped by the stop junction. The red cells begin to stack up like coins (rouleaux formation). The rouleaux effect allows increasing light transmission through the sample (and less scattering) in the time interval between points 2 and 3 . At point 3 , clot formation ends rouleaux formation and transmission through the sample reaches a maximum. The PT time can be calculated from the interval B between points 1 and 3 or between 2 and 3 . Thereafter, blood changes state from liquid to a semi-solid gel, with a corresponding reduction in light transmission. The reduction in current C between the maximum 3 and endpoint 4 correlates with fibrinogen in the sample. [0067] The device pictured in FIG. 2 and described above is preferably formed by laminating thermoplastic sheets 26 and 28 to a thermoplastic intermediate layer 24 that has adhesive on both of its surfaces. The cutouts that form the elements shown in FIG. 1 may be formed, for example, by laser- or die-cutting of layers 24 , 26 , and 28 . Alternatively, the device can be formed of molded plastic. Preferably, the surface of sheet 28 is hydrophilic. (Film 9962, available from 3M, St. Paul. Minn.) However, the surfaces do not need to be hydrophilic, because the sample fluid will fill the device without capillary forces. Thus, sheets 26 and 28 may be untreated polyester or other thermoplastic sheet, well known in the art. Similarly, since gravity is not involved in filling, the device can be used in any orientation. Unlike capillary fill devices that have vent holes through which sample could leak, the present device vents through the sample port before sample is applied, which means that the part of the strip that is first inserted into the meter is without an opening, reducing the risk of contamination. [0068] [0068]FIG. 6 is a plan view of another embodiment of the device of the present invention, in which the device to includes a bypass channel 52 that connects channel 16 with bladder 14 . The function and operation of the bypass channel can be understood by referring to FIGS. 6A, 6B, and 6 C which depict a time sequence during which a sample is drawn into device 10 for the measurement. [0069] [0069]FIG. 6A depicts the situation after a user has applied a sample to the strip, while bladder 14 is compressed. This can be accomplished by applying one or more drops of blood. [0070] [0070]FIG. 6B depicts the situation after the bladder is decompressed. The resulting reduced pressure in the inlet channel 16 draws the sample initially into the measurement area 18 . When the sample reaches stop junction 22 , the sample encounters a back pressure that causes it to stop and causes additional sample to be drawn into the bypass channel. [0071] [0071]FIG. 6C depicts the situation when a reading is taken. Sample is isolated and at rest in measurement area 18 . Excess sample and/or air has been drawn into bypass channel 52 . [0072] The bypass channel of FIG. 6 provides an important improvement over the operation of the “basic” strip-of FIGS. 1 - 3 . In the basic strip, stop junction 22 stops the flow of sample after it fills measurement area 18 . As was discussed earlier, it is important to stop the flow in order to facilitate rouleaux formation. As was also discussed earlier, the stop junction accomplishes the flow stoppage as a result of surface tension acting on the meniscus at the leading edge of the fluid at an abrupt change in cross section of the flow channel. In the basic strip, the pressure on the bladder side of the stop junction remains below atmospheric pressure while the pressure on the sample side remains open to atmosphere. Thus, there is an ambient pressure imbalance on the two sides. The greater the imbalance, the greater the risk that the stop junction will leak and that sample will flow through the stop junction, interfering with rouleaux formation, and, consequently, providing inaccurate values of PT. [0073] Bypass channel 52 minimizes that risk. The reduced pressure on the bladder side of the stop junction draws sample into the bypass channel (FIGS. 6B, 6C) until the ambient pressure is equalized at atmospheric pressure on both sides of the stop junction. Note that the (reduced) pressure on the bladder side is relatively uncontrolled. The bypass channel 52 , by enabling the pressures on the two sides of the stop junction to equilibrate, permits the use of larger bladders that have greater suction. Larger bladders, in turn, provide more reliable operation of the system. [0074] [0074]FIG. 7 depicts an embodiment of the present invention in which there are multiple (three are shown) measurement areas “in parallel”. That is to say that the channels 116 P, 216 P, and 316 P fill substantially simultaneously (assuming they have the same dimensions). The situation depicted in FIG. 7, with channels and measurement areas filled with blood, is achieved, as discussed above, by applying sample to sample pott 112 while bladder 114 is compressed, then releasing bladder 114 . As discussed above, the first step is to apply sample to sample well 112 while bladder 114 is compressed. The second step is to release the bladder. Sample flows to measurement areas 118 P, 218 P, and 318 P, and flow stops when sample reaches stop junctions, 122 P, 222 P, and 322 P, respectively. The optional second and third measurement areas may contain, for example, reagents that neutralize the presence of interferents (such as heparin) in the blood, or that provide a built-in control on the PT measurement, or that measure another blood parameter (such as APPT) [0075] [0075]FIG. 8 is a schematic illustration of an embodiment in which multiple measurement areas are “in series”, meaning that they fill sequentially. In this embodiment, measurement areas 118 S, 218 S, and 318 S fill sequentially, through a single channel 116 S, until the sample reaches stop junction 122 S. A potential drawback of this design is that sample passing from one measurement area to the next may carry over reagent. [0076] [0076]FIG. 9 is a schematic of another embodiment of a device that is adapted for multiple sequential tests. In that embodiment stop junctions 122 T, 222 T, and 322 T permit a user to control the timing of sequential filling of measurement areas 118 T, 218 T, and 318 T. In operation, bladders 114 , 214 , and 314 are all compressed before a blood sample is applied to sample well 112 . Bladder 114 is then released to draw blood into measurement area 118 T to stop junction 122 T. At a selected later time, bladder 214 is released to permit blood to break through stop junction 122 T and enter measurement area 218 T to stop junction 222 T. Finally, when the user wishes to use measurement area 318 T, bladder 314 is decompressed, permitting sample to break through stop function 222 T and flow to stop junction 322 T. The device of FIG. 9 must be carefully formed, since the force drawing sample into the device—caused by decompressing a bladder—must be balanced against the opposing force—exerted by a stop junction. If the drawing force is too great, a stop junction may prematurely permit sample to pass; if it's too small, it will not draw the sample through a stop junction, when that is intended. [0077] [0077]FIG. 10 depicts a preferred embodiment of the present device. It is a parallel multi-channel device that includes bypass channel 152 P. Bypass channel 152 P serves a purpose in this device that is analogous to that served by bypass channel 52 in the device of FIG. 6, which was described above. Measurement area 118 P contains thromboplastin. Preferably, measurement areas 218 P and 318 P contain controls, more preferably, the controls described below. Area 218 P contains thromboplastin, bovine eluate, and recombinant Factor VIIa. The composition is selected to normalize the clotting time of a blood sample by counteracting the effect of an anticoagulant, such as warfarin. Measurement area 318 P contains thromboplastin and bovine eluate alone, to partially overcome the effect of an anticoagulent. Thus, 3 measurements are made on the strip. PT time of the sample, the measurement of primary interest, is measured on area 118 P. However, that measurement is validated only when measurements on areas 218 P and 318 P yield results within a predetermined range. If either or both of these control measurements are outside the range, then a retest is indicated. Extended stop junction 422 stops flow in all three measurement areas. [0078] [0078]FIG. 11 depicts a device that includes bypass channels 152 S and 252 S to permit timed filling of measurement areas 118 T and 218 T. Operation of the device of FIG. 11 is analogous to that of the device of FIG. 9, described above, with the following exception. First bypass channel 152 S has a region in which a reagent that causes clotting, such as thromboplastin, is coated. As a first measurement is made in reagent area 118 T, a clot forms in blood that had been drawn into bypass channel 152 S. Thus, when the second bladder is decompressed, blood is blocked from being drawn through bypass 152 S and instead is drawn though stop junction 122 T to measurement area 218 T and bypass channel 252 S. [0079] All the previous figures depict the device of this invention as a laminated strip structure; however, the device could also be an injection-molded structure of the type shown in FIGS. 12 and 13. FIG. 12 is an exploded view of an injection-molded device 110 , including top layer 126 and bottom layer 128 sandwiching intermediate layer 124 . The intermediate layer has depressions in its top surface that form sample port 112 , channel 116 , measurement area 118 , and optional bypass channel 152 . Stop junction 122 passes through the thickness of intermediate layer 124 . Sample flow stops at the interface between stop junction 122 and channel A, which is formed by a depression in the bottom surface. Thus, the sample flows from sample port 112 through channel 116 to measurement area 118 into stop junction 122 . [0080] The principle of operation of the injection molded device is the same as described above. It provides greater flexibility in the design of the stop junction, as well as the other elements of the device, because a wide range of channel cross sections are feasible. The molded structure also provides more rigidity, although it is substantially more costly. [0081] The following examples demonstrate the present invention in its various embodiments, but are not intended to be in any way limiting. EXAMPLE 1 [0082] A strip of this invention is made by first passing a double-sided adhesive tape (RX 675SLT, available from Scapa Tapes, Windsor, Conn.) sandwiched between two release liners into a laminating and rotary die-cutting converting system. The pattern shown in FIG. 6, with the exception of the stop junction, is cut through the top release liner and tape, but not through the bottom release liner, which is then removed as waste, along with the cutouts from the tape. Polyester film treated to be hydrophilic (3M9962, available from 3M, St. Paul, Minn.) is laminated to the exposed bottom side of the tape. Reagent (thromboplastin, available from Ortho Clinical Diagnostics, Raritan, N.J.) is then printed onto the reagent area ( 18 ) of the polyester film by bubble jet printing, using printing heads 51612A, from Hewlett Packard, Corvallis, Oreg. A sample port is cut in untreated polyester film (AR1235, available from Adhesives Research, Glen Rock, Pa.) and then laminated, in register, to the top of the double-sided tape (after removing the release layer). A die then cuts the stop junction through the three layers of the sandwich. Finally, strips of single-sided adhesive tape (MSX4841, available from 3M, St. Paul, Minn.) are applied to the outside of the polyester layers to seal the stop junction. EXAMPLE 2 [0083] A procedure that is similar to the one described in Example 1 is followed to make a strip of the type depicted in FIG. 10. Reagent that is bubble-jet printed onto areas 118 P, 218 P, and 318 P is, respectively, thromboplastin; thromboplastin, bovine eluate, and recombinant Factor VIIa; and thromboplastin and bovine eluate alone. The bovine eluate (plasma barium citrate bovine eluate) is available from Haembtologic Technologies, Burlington, Vt.; and recombinant Factor VIIa from American Diagnostica, Greenwich, Conn. [0084] Measurements made on a whole blood sample using the strip of this Example yield a curve of the type shown in FIG. 5 for each of the measurement areas. The data from the curves for the controls (measurement areas 218 P and 318 P) are used to qualify the data from the curve for measurement area 118 P. As a result, the PT time can be determined more reliably than can be done with a strip having a single measurement area. EXAMPLE 3 [0085] The device of FIGS. 12 and 13 is formed by sandwiching middle layer 124 between top layer 126 and bottom layer 128 . The middle and bottom layers are injection molded polycarbonate (Lexan*121) and have thicknesses of 6.3 mm and 1.5 mm, respectively. Top layer 126 is made by die cutting 0.18 mm Lexan* 8010 sheet. The elements are ultrasonically welded after the reagent of Example 1 is applied to reagent area 118 . The Lexan* material is available from General Electric, Pittsfield, Mass. [0086] The invention having been fully described, it will be apparent to one of ordinary skill in the art that many modifications and changes may be made to it without departing from the spirit and scope of the present invention.

A fluidic medical diagnostic device permits measurement of analyte concentration or a property of a biological fluid, particularly the coagulation time of blood. The device has at one-end a sample port for introducing a sample and at the other end a bladder for drawing the sample to a measurement area. A channel carries the sample from the sample port to the measurement area, and a stop junction, between the measurement area and bladder, halts the sample flow. The desired measurement can be made by placing the device into a meter which measures a physical property of the sample—typically, optical transmittance—after it has interacted with a reagent in the measurement area.

FIELD OF THE INVENTION [0001] This invention relates to composite materials for restorative dentistry. More particularly, it relates to a dental composite material that combines reduced shrinkage with sufficiently low viscosity, high polymerization rate, and good mechanical properties. BACKGROUND OF THE INVENTION [0002] In recent years, composite materials comprising highly filled polymer have become commonly used for dental restorations. A thorough summary of current dental composite materials is provided in N. Moszner and U. Salz, Prog. Polym. Sci. 26:535-576 (2001). Currently used dental filling composites contain crosslinking acrylates or methacrylates, inorganic fillers such as glass or quartz, and a photoinitiator system, enabling them to be cured by radiation with visible light. Typical methacrylate materials include 2,2′-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (“Bis-GMA”); ethoxylated Bis-GMA (“EBPDMA”); 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,4,4-trimethylhexane (“UDMA”); dodecanediol dimethacrylate (“D 3 MA”); and triethyleneglycol dimethacrylate (“TEGDMA”). [0003] Dental composite materials offer a distinct cosmetic advantage over traditional metal amalgam. However, they do not offer the longevity of amalgam in dental fillings. The primary reasons for failure are believed to be excessive shrinkage during photopolymerization in the tooth cavity, which causes leakage and bacterial reentry, and inadequate strength and toughness. [0004] The incumbent low-shrink monomer, Bis-GMA, the condensation product of bisphenyl A and glycidyl methacrylate, is an especially important monomer in dental composites. However, it is highly viscous at room temperature and consequently insufficiently converted to polymer. It is therefore typically diluted with a less viscous acrylate or methacrylate monomer, such as trimethylol propyl trimethacrylate, 1,6-hexanediol dimethacrylate, 1,3-butanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, TEGDMA, or tetraethylene glycol dimethacrylate. However, while providing fluidity, low molecular weight monomers contribute to increased shrinkage. Increasingly, Bis-GMA and TEGDMA have been combined with UDMA and ethoxylated-methacrylated versions of bisphenyl A, but shrinkage remains too high. [0005] Increasing the amount of inorganic filler in the composite has moderated shrinkage. However, the amount of filler that can be added is severely limited by the resulting increase in viscosity. Also, it has been reported that the increase in modulus more than offsets this benefit and can lead to an increased build-up of stress during shrinkage. This “contraction stress” is of great importance in that it can lead to mechanical failure and debonding of the composite from the tooth, creating a gap that can permit microleakage of oral fluid and bacteria, causing a reinfection. [0006] Another approach has been to prepolymerize the monomer, reducing the ultimate degree of polymerization and attendant shrinkage. However, this reduces the amount of inorganic filler that can be added below current levels, thus decreasing the modulus and other mechanical properties. [0007] Spiro-type, “expanding” monomers, introduced in the 1970s, eliminate shrinkage, but they have never been commercialized because they polymerize too slowly and they, or their polymerization products, are too unstable. Diepoxide monomers are similarly limited in that they polymerize slowly for practical application, and the monomers and photosensitizers may be too toxic. They do not entirely eliminate shrinkage. [0008] Slow cure and the so-called “soft start” photocure are also reported to reduce contraction stress. [0009] Other systems have been reported in the literature but are not commercial. Liquid crystalline di(meth)acrylates shrink far less, but there is a tradeoff in mechanical properties. Branched polymethacrylates and so-called “macromonomers” offer lower viscosity at reduced shrinkage, but cost of manufacture may be excessive. [0010] Published, unexamined Japanese Application JP2001122721 discloses tetramethylspirobisindanediol compounds wherein the benzene ring side chains comprise linear or branched (poly)oxyalkylenes with terminal (meth)acrylates. [0011] U.S. Pat. No. 5,486,548 issued to Podszun et al. on Jan. 23, 1996, discloses di(meth)acrylate derivatives of cyclohexyldiphenyls that, when used in dental compositions, display a low degree of shrinkage upon polymerization. [0012] B. Culbertson et al., Poly. Adv. Tech. 10:275-281 (1999) describes the synthesis and use of ethoxymethacrylate and propoxymethacrylate derivatives of fluorenylbisphenyl A. [0013] U.S. Pat. No. 6,608,167 issued to Hayes et al. on Aug. 19, 2003, discloses a process for producing bis(2-hydroxyethyl)isosorbide. [0014] There remains a need for a dental composite material that combines reduced shrinkage with sufficiently low viscosity, high polymerization rate, and acceptable mechanical properties. SUMMARY OF THE INVENTION [0015] The present invention provides a dental composite material comprising at least one (meth)acrylic ester compound, at least one polymerization initiator, at least one inorganic filler, and at least one space-filling compound. The invention also provides a method of producing a dental restoration article using at least one (meth)acrylic ester compound, at least one polymerization initiator, at least one inorganic filler, and at least one space-filling compound. [0016] Further disclosed is a method of treating dental tissue with a direct composite, comprising the steps of: (a) placing a dental composite material, as desribed above, on a dental tissue; (b) curing the dental composite material; and (c) shaping the dental composite material. DETAILED DESCRIPTION OF THE INVENTION [0020] Applicants specifically incorporate the entire content of all cited references in this disclosure. Applicants also incorporate by reference the co-owned and concurrently filed applications entitled “Dental Composites Containing Core-Shell Polymers with Low Modulus Cores” (Attorney Docket # CL 2434), “Dental Compositions Containing Liquid and Other Elastomers” (Attorney Docket # CL 2368), and “Branched Highly-Functional Monomers Exhibiting Low Polymerization Shrinkage” (Attorney Docket # CL 2452). [0021] In the context of this disclosure, a number of terms shall be utilized. [0022] The terms “(meth)acrylic” and “(meth)acrylate” as used herein denote “methacrylic or acrylic” and “methacrylate or acrylate” respectively. [0023] The term “dental composite material” as used herein denotes a composition that can be used to remedy natural or induced imperfections of, and relating to, teeth. Examples include filling materials, reconstructive materials, restorative materials, crown and bridge materials, inlays, onlays, laminate veneers, dental adhesives, teeth, facings, pit and fissure sealants, cements, denture base and denture reline materials, orthodontic splint materials, and adhesives for orthodontic appliances. [0024] Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. [0025] The (meth)acrylic ester compound used in the present invention can comprise either a monofunctional compound or a polyfunctional compound which means a compound having one (meth)acrylic group and a compound having more than one (meth)acrylic group respectively. Specific examples of monofunctional (meth)acrylic ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and methacryloyloxyethyltrimellitic mono ester and its anhydride. [0026] Specific examples of polyfunctional (meth)acrylic ester compounds include di(meth)acrylates of ethylene glycol derivatives as represented by the general formula wherein R is hydrogen or methyl and n is an integer in a range of from 1 to 20, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dodecanediol di(meth)acrylate, glycerol di(meth)acrylate, bisphenyl A di(meth)acrylate, bisphenyl A diglycidyl di(meth)acrylate and ethoxylated bisphenyl A diglycidyl di(meth)acrylate; urethane di(meth)acrylates; trimethylolpropane tri(meth)acrylate; tetrafunctional urethane tetra(meth)acrylates; pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and hexa(meth)acrylates of urethanes having an isocyanuric acid skeleton. [0027] These (meth)acrylic ester compounds may be used alone or in admixture of two or more. The mixtures can be mixtures of monofunctionals, polyfunctionals, or both. [0028] The (meth)acrylic ester compound used in the dental compositions preferably comprises at least one polyfunctional (meth)acrylic ester compound, and more preferably comprises at least two polyfunctional (meth)acrylic ester compounds. [0029] The space-filling compound of the present invention is a monomer comprising a rigid, angular, bulky moiety that can be compounded into composites, which upon polymerization exhibit low volumetric shrinkage. By “space-filling compound” is meant a monomer comprising a moiety with an inability of a significant fraction of its constituent atoms to be place in a common plane. By “significant fraction” is meant greater than about 15%. Additionally, the constituent atoms have a relative lack of mobility with respect to one another; that is, the moiety's structure is highly rigid and preferably has less than two freely rotating internal bonds. [0030] In accordance with one aspect of the invention, the space-filling compounds comprise derivatives of at least one of the moieties spirobisindanediol (“SBID”), phenylindane dicarboxylic acid (“PIDA”), t-butylisophthalic acid (“BIPA”), cyclohexyldiphenyl, fluorenylbisphenyl A, tetrahydrodicyclopentadiol, phenyl-alkyl levulinate, and isosorbide. [0031] Preferred SBID-based space-filling compounds comprise at least one of compound (i) or (ii): wherein R 1 and R 2 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacryl ate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 3 and R 4 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 5 and R 6 are independently H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 3 and R 4 respectively; provided when R 3 and R 4 are CH 3 and R 5 and R 6 are H that R 1 and R 2 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 1 and R 2 are 2-(2-ethoxycarbonylamino)ethyl methacrylate, R 3 and R 4 are CH 3 , and R 5 and R 6 are H; and wherein R 7 and R 8 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 9 and R 10 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 11 and R 12 are independently H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 9 and R 10 respectively. Preferably, R 7 and R 8 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate, R 9 and R 10 are CH 3 , and R 11 and R 12 are H. [0032] Preferred PIDA-based space-filling compounds (iii) comprise wherein R 13 and R 14 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 15 , R 16 , and R 17 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 18 is H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 15 , R 16 , or R 17 . Preferably, R 13 and R 14 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate, R 15 , R 16 , and R 17 are CH 3 and R 18 is H. [0033] Preferred phenyl-alkyl levulinate-based space-filling compounds (iv) comprise wherein R 19 and R 20 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 21 , R 22 , and R 23 are independently H, CH 3 , alkyl, or aralkyl. Preferably, R 19 and R 20 are 2-(2-ethoxycarbonylamino)ethyl methacrylate, R 21 is ethyl and R 22 and R 23 are H. [0034] Preferred cyclohexyldiphenyl-based space-filling compounds (v) comprise wherein R 24 and R 25 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; and R 26 and R 27 are independently H, CH 3 , alkyl, or aralkyl; provided when R 26 and R 27 are H that R 24 and R 25 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 24 and R 25 are 2-(2-ethoxycarbonylamino)ethyl methacrylate and R 26 and R 27 are H. [0035] Preferred fluorenylbisphenyl A-based space-filling compounds (vi) comprise wherein R 28 and R 29 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; and R 30 and R 31 are independently H, CH 3 , alkyl, or aralkyl; provided when R 30 and R 31 are H or CH 3 that R 28 and R 29 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 28 and R 29 are 2-(2-ethoxycarbonylamino)ethyl methacrylate and R 30 and R 31 are H. [0036] Preferred tetrahydrodicyclopentadiol-based space-filling compounds (vii) comprise wherein R 32 and R 33 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacryl ate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 32 and R 33 are 2-(2-ethoxycarbonylamino)ethyl methacrylate. [0037] Preferred isosorbide-based space-filling compounds (viii) comprise wherein R 34 and R 35 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 34 and R 35 are 2-(2-ethoxycarbonylamino)ethyl methacrylate. [0038] Preferred BIPA-based space-filling compounds (ix) comprise wherein R 36 and R 37 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 36 and R 37 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate. [0039] Monomers of diol-based space-filling compounds can be reacted with ethylene or propylene oxide, for example, to produce low molecular weight alkoxylate oligomers that can then be (meth)acrylated to produce free radical-polymerizable monomers. Monomers of dicarboxylic acid-based space-filling compounds can be esterfied with diols, for example, to produce low molecular weight esterdiol oligomers that can then be (meth)acrylated to produce free radical-polymerizable monomers. [0040] In another aspect of the invention, dental composite materials comprise a space-filling compound that has been functionally terminated with at least two urethane (meth)acrylate groups. Preferably, the space-filling compound is functionally terminated with 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; or 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate. [0041] In dental composite materials, space-filling compounds of the present invention can be used in the range of about 1 weight percent to 100 weight percent, preferably in the range of about 20 weight percent to about 80 weight percent, and more preferably in the range of about 40 weight percent to about 60 weight percent, the percentages being based on the total weight exclusive of filler. [0042] The production of the crosslinked polymers useful in the practice of this invention from monomers and crosslinking agents may be performed by any of the many processes known to those skilled in the art. Thus, the polymers may be formed by heating a mixture of the components to a temperature sufficient to cause polymerization. For this purpose, peroxy-type initiators such as benzoyl peroxide, dicumyl peroxide, lauryl peroxide, tributyl hydroperoxide, and other materials familiar to those skilled in the art may be employed, and the use of activators may be advantageous in some formulations. Suitable activators include, for example, N,N-bis-(hydroxyalkyl)-3,5-xylidines, N,N-bis-(hydroxyalkyl)-3,5-di-t-butylanilines, barbituric acids and their derivatives, and malonyl sulfamides, including specific examples of these activators found in published U.S. Patent Application 2003/0008967. Azo-type initiators such as 2,2′-azobis(isobutyronitrile), 2,2′-azobis(2,4-dimethyl valeronitrile), 2,2′-azobis(2-methyl butane nitrile), and 4,4′-azobis(4-cyanovaleric acid) may also be used. Alternatively, the crosslinked polymers of the invention may be formed from the constituents by photochemical or radiant initiation utilizing light or high energy radiation. For photochemical initiation, photochemical sensitizers, or energy transfer compounds may be employed to enhance the overall polymerization efficiency in manners well known to those skilled in the art. [0043] Suitable photoinitiators include, for example, camphor quinone, benzoin ethers, α-hydroxyalkylphenones, acylphosphine oxides, α,α-dialoxyacetophenones, α-aminoalkylphenones, acyl phosphine sulfides, bis acyl phosphine oxides, phenylglyoxylates, benzophenones, thioxanthones, metallocenes, bisimidazoles, and α-diketones. [0044] Photoinitiating accelerators may also be present. Such photoinitiating accelerators include, for example, ethyl dimethylaminobenzoate, dimethylaminoethyl methacrylate, dimethyl-p-toluidine, and dihydroxyethyl-p-toluidine. [0045] According to another aspect, an inorganic filler is included in the composite. Included in the inorganic fillers are the preferred silicious fillers. More preferred are the inorganic glasses. Among these preferred inorganic fillers are barium aluminum silicate, lithium aluminum silicate, strontium fluoride, lanthanum oxide, zirconium oxide, bismuth phosphate, calcium tungstate, barium tungstate, bismuth oxide, tantalum aluminosilicate glasses, and related materials. Glass beads, silica, especially in submicron sizes, quartz, borosilicates, alumina, alumina silicates, and other fillers may also be employed. For example, Aerosil® OX-50 fumed silica from Degussa can be used. Mixtures of fillers may also be employed. The average diameter of the inorganic fillers is preferably less than 15 μm, even more preferably less than 10 μm. [0046] Such fillers may be silanated prior to use in this invention. Silanation is well known to those skilled in the art and any silanating compound known to them may be used for this purpose. By “silanation” is meant that some of the silanol groups have been substituted or reacted with, for example, dimethyldichlorosilane to form a hydrophobic filler. The particles are typically from 50 to 95 percent silanated. Silanating agents for inorganic fillers include, for example, γ-mercaptoproyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltriethoxysilane. [0047] The (meth)acrylic ester compound can be used in the range of about 1 weight percent to about 99 weight percent, preferably in the range of about 20 weight percent to about 80 weight percent, and more preferably in the range of about 40 weight percent to about 60 weight percent, the percentages being based on the total weight exclusive of filler. [0048] The polymerization initiator with, optionally, a photoinitiating accelerator can be used in the range of about 0.1 weight percent to about 5 weight percent, preferably in the range of about 0.2 weight percent to about 3 weight percent, and more preferably in the range of about 0.2 weight percent to about 2 weight percent, the percentages being based on the total weight exclusive of filler. [0049] The inorganic filler can be used in the range of about 20 weight percent to about 90 weight percent, preferably in the range of about 40 weight percent to about 90 weight percent, and more preferably in the range of about 50 weight percent to about 85 weight percent, the percentages being based on the total weight of the (meth)acrylic ester compound, the polymerization initiator, the inorganic filler, and the space-filling compound. [0050] In addition to the components described above, the blend may contain additional, optional ingredients. These may comprise activators, pigments, radiopaquing agents, stabilizers, antioxidants, and other materials as will occur to those skilled in the art. [0051] Suitable pigments include, for example, inorganic oxides such as titanium dioxide, micronized titanium dioxide, and iron oxides; carbon black; azo pigments; phthalocyanine pigments; quinacridone pigments; and pyrrolopyrrol pigments. [0052] Preferred radiopaquing agents include, for example, ytterbium trifluoride, yttrium trifluoride, barium sulfate, bismuth subcarbonate, bismuth trioxide, bismuth oxichloride, and tungsten. [0053] Preferred stabilizers can include, for example, hydroquinone, hydroquinone monomethyl ether, 4-tert-butylcatechol, and 2,6-di-tert-butyl-4-methylphenyl. [0054] Primary antioxidants, secondary antioxidants, and thioester-type antioxidants are all suitable for use in the dental compositions of the invention. Preferred primary antioxidants comprise hindered phenyl and amine derivatives such as butylated hydroxytoluene, butylated hydroxyanisole, t-butyl hydroquinone, and α-tocopherol. Preferred secondary antioxidants include phosphites and phosphonites such as tris(nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, and Irgafos® P-EPQ (Ciba Specialty Chemicals, Tarrytown, N.Y.). Preferred thioester-type antioxidants, used synergistically or additively with primary antioxidants, include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, and ditridecyl 3,3′-thiodipropionate. [0055] Organic fillers, comprising prepolymerized material, optionally comprising at least one of the (meth)acrylic ester compounds and space-filling compounds, and optionally comprising inorganic filler, may also be included in the composite material. Prepolymerization filler can be produced by any method known in the art, for example, by the method described in published U.S. patent application 2003/0032693. Optionally, uniformly-sized bead methacrylate polymers, such as Plexidon® or Plex® available from Röhm America LLC (Piscataway, N.J.), may be utilized as organic fillers. [0056] The dental composite materials of the present invention can be used in any treatment method known to one of ordinary skill in the art. Treatment in this context includes preventative, restorative, or cosmetic procedures using the dental composites of the present invention. Typically, without limiting the method to a specific order of steps, the dental composite materials are placed on a dental tissue, either natural or synthetic, the dental composite materials are cured by any method known to one of ordinary skill in the art, and the dental composite materials are shaped as necessary to conform with the target dental tissue. Dental tissue includes, but is not limited to, enamel, dentin, cementum, pulp, bone, and gingiva. [0057] The dental composite materials of the present invention are suitable for a very wide range of dental uses, including fillings, teeth, bridges, crowns, inlays, onlays, laminate veneers, facings, pit and fissure sealants, cements, denture base and denture reline materials, orthodontic splint materials, and adhesives for orthodontic appliances. The materials of the invention may also be utilized for prosthetic replacement or repair of various hard body structures such as bone and may be utilized for reconstructive purposes during surgery, especially oral surgery. They are also useful for various non-dental uses as, for example, in plastic construction materials. EXAMPLES [0058] The present invention is further defined in the following Examples. It should be understood that these Examples, while indicating preferred embodiments of the invention, are given by way of illustration only. From the above discussion and these Examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various uses and conditions. [0059] The meaning of abbreviations is as follows: “hr.” means hour(s), “min.” means minute(s), “sec.” means second(s), “ml” means milliliter(s), “cm” means centimeter(s), “mm” means millimeter(s), “g” means gram(s), “mmol” means millimole(s), “wt %” means weight percent(age), “mW” means milliwatt(s), “atm.” means atmosphere(s), “M n ” means number average molecular weight, “MPa” means megapascal(s), “d50” means 50% of particles have a diameter below a given size, “MEHQ” means 4-methoxyphenyl, “PTFE” means polytetrafluoroethylene, “TH F” means tetrahydrofuran. Example 1 Bis-GMA/TEGDMA Glass Composition [0060] A masterbatch containing 15.0 g Bis-GMA (Sigma-Aldrich, St. Louis, Mo.), 15.0 g TEGDMA (Sigma-Aldrich), 0.40 g camphor quinone (Sigma-Aldrich), and 0.40 g ethyl 4-N,N-dimethylaminobenzoate (Sigma-Aldrich) was made up by mixing the components well under subdued light. Then, 5.0 g of this masterbatch was combined and mixed well with 1.0 g untreated Degussa OX-50 fumed silica followed by 14.0 g Schott 8235 UF1.5 (d50=1.5 micron) glass powder coated with 2.3 wt % trimethoxysilylpropyl methacrylate. The blend was then placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 60 times. The resin-glass mixture was degassed under 40 mm Hg vacuum for 18 hr. at room temperature followed by heating in a vacuum oven at 45° C. with very slight vacuum for an additional 16 hr. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. Example 2 Synthesis of Tetramethylspirobisindanediol (“SBID”) [0061] A mixture of 500 g bisphenyl A and 1000 ml 48% aqueous hydrobromic acid was stirred at reflux under nitrogen overnight (about 16 hrs.) in a 2 l 3-neck flask with overhead stirrer and reflux condenser. The mixture was cooled to room temperature, and the upper red phase, which contained the product, solidified. The hydrobromic acid was decanted off, and the solid product was crushed and washed on a fritted filter funnel with water until the washes were neutral to pH paper. [0062] The product was taken up in 500 ml boiling methanol and precipitated by addition of 700 ml water to the boiling solution. Suction filtration of the thick slurry yielded a tan powder that was taken up in 600 ml boiling methanol. Addition of 100 ml water just started to cause precipitation, so 10-20 ml methanol was added to form a clear solution, and then the mixture was cooled in ice. The solids were suction filtered and taken up in 400 ml boiling methanol. This solution was cooled in ice, the resulting slurry was suction filtered, and the solids were washed with 2×100 ml methanol. Air-drying on the funnel yielded 67 g tetramethylspirobisindanediol (“SBID”). The filtrate was evaporated down to about half its volume and chilled in ice. Suction filtration yielded 72 g less pure SBID. [0063] The resulting compound has the formula: [0064] Lower case letters refer to 1 H NMR (CDCl 3 ; sparingly soluble) results as follows: 1.31 ppm (s, a, 3H); 1.36 (s, a′, 3H); 2.22 (d, J=13.1 Hz, b, 1H); 2.32 (d, J=13.1 Hz, b, 1H); 4.38 (s, C, 1H); 6.20 (d, J=2.3 Hz, d, 1H); 6.68/6.71 (d of d, J=2.4, 8.2 Hz, e, 1H); 7.02 (d, J=8.2 Hz, f, 1H). Example 3 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxyethyl Ether) (“SBID EO”) [0065] A 5.0 g sample (16 mmol; 32 mmol OH) of SBID from Example 2 was dissolved in 50 ml MeOH. The hazy solution was clarified through a 5-micron syringe filter and combined with 0.5 g (4.5 mmol) potassium t-butoxide in a 100 ml RB flask. A dry ice condenser and gas inlet were attached to the flask containing the pink solution, and 6.5 g (150 mmol) ethylene oxide (“EO”) was condensed into the flask. The solution became warm upon introduction of the EO. The solution was stirred at reflux under nitrogen in a 70° C. water bath for 4 hr. The solution was allowed to stand at room temperature overnight and was then rotovapped to give a white-pink solid. The powdery solid was suspended in 50 ml water, acidified with aqueous HCl, and stirred for 30 min. The suspension was suction filtered, water washed to neutral pH, and air dried under suction to yield 6.05 g off-white powder tetramethylspirobisindane bis(2-hydroxyethyl ether) (“SBID EO”). [0066] The resulting compound has the formula: [0067] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.32 ppm (s, a, 3H); 1.38 (s, a′, 3H); 2.02 (t, J=6.4 Hz, b, 1H); 2.24 (d, J=13.1 Hz, c, 1H); 2.34 (d, J=13.1 Hz, c′, 1H); 3.86 (q, J=4.9 Hz, d, 2H); 3.97 (t, J=4.6 Hz, e, 2H); 6.34 (d, J=2.4 Hz, f, 1H); 6.79/6.80 (d of d, J=2.6, 8.2 Hz, g, 1H); 7.07 (d, J=8.2 Hz, h, 1H). [0068] There were also several small triplets due to impurities at 2.11, 2.17, 3.61, 3.78, and 4.02 ppm as well as a quartet at 3.69. The impurities are due to multiple EO additions. Example 4 Synthesis of Tetramethylspirobisindane Bis[2-(2-Ethoxycarbonylamino)ethyl Methacrylate] (“SBID EOUMA”) [0069] A mixture of 3.0 g (15 mmol OH) SBID EO from Example 3, 1 drop of dibutyltin diacetate, 10 mg MEHQ, and 2.7 g (17 mmol) 2-isocyanatoethyl methacrylate in 20 ml THF in a 200 ml RB flask was stirred in a 60° C. oil bath for 1 hr. [0070] The light tan solution was quickly rotovapped to remove over half of the solvent, and the liquid concentrate was stirred with 100 ml hexane for 1 hr. The hexane was decanted from the taffy-like product, and 100 ml fresh hexane was added. The mixture was stirred for 1 hr., and the hexane was decanted off. A solution of 10 mg MEHQ in 2 ml dichloromethane was added and mixed well. The solution was held under vacuum with an air bleed to remove solvent, yielding 5.68 g tetramethylspirobisindane bis[2-(2-ethoxycarbonylamino)ethyl methacrylate] (“SBID EOUMA”). NMR indicated complete conversion of the SBID EO hydroxyls to urethane methacrylate groups, the OH peak at 2.02 ppm having been replaced by the methacrylate methyl at 1.92 ppm. [0071] The resulting compound has the formula: [0072] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.31 ppm (s, a, 3H); 1.37 (s, a′, 3H); 1.92 (s, b, 3H); 2.23 (d, J=13.1 Hz, c, 1H); 2.33 (d, J=13.1 Hz, c′, 1H); 3.48 (br m, d, 2H); 4.04 (t, e, 2H); 4.20 (t, f, 2H); 4.35 (t, g, 2H); 5.09 (t, h, <1H); 5.56 (s, i, 1H); 6.09 (s, j, 1H); 6.32 (d, J=2.2 Hz, k, 1H); 6.77/6.79 (d of d, J=2.6, 8.2 Hz, l, 1H); 7.07 (d, J=8.2 Hz, m, 1H). Example 5 SBID EOUMA/TEGDMA—Glass Composition [0073] A TEGDMA/photoinitiator masterbatch was produced by combining 10.0 g TEGDMA with a solution of 0.20 g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Sigma-Aldrich) in 0.5 ml dichloromethane. The flask was covered with foil, and the solution magnetically stirred under 10-20 mm Hg vacuum for 1 hr. with an air bleed to carry off solvent. [0074] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch and 1.25 g SBID EOUMA from Example 4 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hrs. and then in an oven at 45° C. under 1 atm. air for 24 hrs. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described below in Example 6. Example 6 [0075] Fracture toughness (K IC ), flexural strength (ISO 4049), and density were determined on molded and cured bars of the resin composition (Bis-GMA/TEGDMA from Example 1 and SBID EOUMA/TEGDMA from Example 5). Bars (2 mm×2 mm×25 mm) were molded and cured by irradiating 2 min. on a side using an array of three Denstply Spectrum 800 dental lamps at 800 mW/cm 2 . The metal mold was covered on both sides with a 3-mil polyester film to exclude oxygen, which would inhibit cure. [0076] The fracture toughness test was based on both the ASTM polymers standard (ASTM D5045) and the ASTM ceramics standard (ASTM C1421, precracked beam method). Testing was conducted at a test speed of 0.5 mm/min. at room temperature and ambient humidity using a three-point bend fixture (span to depth ratio of 10). The specimens were molded using the flex bar mold specified in ISO 4049. The specimens were precracked halfway through the depth. Two modifications to the test procedures were made. The first was the use of smaller test specimens than those recommended in the ASTM C1421 standard (2 mm×2 mm×25 mm instead of the recommended minimum dimensions of 3 mm×4 mm×20 mm). The second was the use of a slitting circular knife to machine the precracks. The knife was 0.31 mm in thickness with a 9 degree single bevel. Tests have shown that this technique produced precracks that were equivalent to precracks produced using techniques recommended in ASTM D5045. [0077] Density determination was accomplished via helium pycnometry. The densities of the uncured glass-resin blends were determined as well. [0078] Polymerization shrinkage was determined by the equation: [(ρ cured −ρ uncured )/(ρ cured )]×100%=% S. [0079] As seen in Table 1, use of the bulky monomer with the spirobisindane structure reduced polymerization shrinkage by over 25% relative to the bisphenyl A monomer control composition without significantly reducing mechanical properties. TABLE 1 Resin Mixture SBID EOUMA/ (1:1) Bis-GMA/TEGDMA TEGDMA Shrinkage, % 4.56 3.37 K IC , MPa · m 1/2 1.88 1.69 Flex Strength, 118 129 MPa · m 1/2 Example 7 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxypropyl Ether) (“SBID PO”) [0080] A 5.0 g sample (32.5 mmol OH) of SBID from Example 2 was combined with 0.1 g 2-methylimidazole and 3.5 ml (4.2 g; 41 mmol) propylene carbonate in a 100 ml RB flask under nitrogen. The dark, fluid homogeneous melt was magnetically stirred in a 180° C. oil bath for 5 hrs., and then 75 ml water was added slowly down the condenser. This mixture was stirred at reflux for 15 mins., the flask was then cooled, and the water decanted off. The solid product was broken up, and 75 ml fresh water was added. The mixture was stirred at reflux for another 15 min. The suspension was cooled and suction filtered dry to yield 6.76 g tetramethylspirobisindane bis(2-hydroxypropyl ether) (“SBID PO”). NMR indicated clean conversion to PPO diadduct. [0081] The resulting compound has the formula: [0082] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.21/1.23 ppm (s, a, 6H); 1.32/1.38 (s, b, 12H); 1.63/2.31 (br s, J=268 Hz, c, 2H); 2.24 (d, J=13.1 Hz, d, 2H); 2.34 (d, J=13.1 Hz, d, 2H); 3.68 (m, e, 2H); 3.83 (d of d, f, 2H); 4.11 (m, g, >1.5H); 4.36 (m, g, <0.5H; may be opposite addition of propylene carbonate); 6.33 (d, J=2.4 Hz, h, 2H); 6.79/6.80 (d of d, J=2.6, 8.2 Hz, i, 1H); 7.08 (d, J=8.2 Hz, h, 2H). Example 8 Synthesis of Bisphenyl A Bis(2-Hydroxypropyl Ether) (“BPA PO”) [0083] A 6.0 g sample (52.6 mmol OH) of bisphenyl A was combined with 0.1 g 2-methylimidazole and 6.0 ml (7.1 g; 70 mmol) propylene carbonate in a 100 ml RB flask under nitrogen. The homogeneous melt was magnetically stirred in a 180° C. oil bath for 5 hrs., and then 75 ml water as added slowly down the condenser. This mixture was stirred at reflux or 15 mins., the flask cooled, and the water decanted off and replaced by 75 ml fresh water. The fluid product was stirred at reflux for another 15 min. and cooled, and the water was decanted off again. The product was held under high vacuum in a boiling water bath for 2 hrs. to yield 8.92 g bisphenyl A bis(2-hydroxypropyl ether) (“BPA PO”). NMR indicated clean conversion to PPO diadduct. There also appeared to be a little PPO oligomer (1.13 ppm) present. [0084] The resulting compound has the following formula: [0085] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.25/1.27 ppm (s, a, 6H); 1.63 (s, b, 6H); 2.41 (br s, c, ˜2H); 3.75/3.78 (d of d, J=7.6 Hz, d, 2H); 3.89/3.92 (d of d, J=3.3 Hz, e, 2H); 4.16 (m, f, >1.5H); 4.45 (m, f, <0.5H; may be opposite addition of propylene carbonate); 6.80 (d, J=8.8 Hz, g, 4H); 7.13 (d, J=8.8 Hz, h, 4H). Example 9 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxylpropyl Ether) Dimethacrylate (“SBID POMA”) [0086] A mixture of 5.0 g (11.8 mmol; 23.6 mmol OH) SBID PO from Example 7, 10.0 g (65 mmol) methacrylic anhydride, and 2.0 g (25 mmol) pyridine was stirred in a 50 ml RB flask under air in a 120° C. oil bath for 5 hrs. The solution was cooled to room temperature, added to 100 ml water containing 8 g sodium carbonate, and stirred for 30 mins. The aqueous mixture was briefly shaken in a separatory funnel with 50 ml diethyl ether. The water was separated, and the ether was shaken briefly with 25 ml of water containing 5 ml concentrated HCl. The acidic water was again separated, and the ether layer was shaken briefly with 20 ml of water containing 2 g sodium carbonate. The ether was separated and dried over magnesium sulfate followed by filtration; 5 mg MEHQ was added to the filtrate. The solution was quickly rotovapped from warm water then held under 20 mm Hg vacuum overnight with an air bleed through a syringe needle to yield 7.04 g tetramethylspirobisindane bis(2-hydroxylpropyl ether) dimethacrylate (“SBID POMA”). [0087] 1 H NMR (CDCl 3 ) indicated 80% conversion to dimethacrylate. The ratio of the integrals of the 5.55 ppm methacrylate vinyl proton to the 7.10 ppm aromatic ring proton equaled 0.80. Example 10 Synthesis of Bisphenyl A Bis(2-Hydroxypropyl Ether) Dimethacrylate (“BPA POMA”) [0088] A mixture of 3.8 g (11 mmol; 22 mmol OH) BPA PO from Example 8, 5.0 g (32 mmol) methacrylic anhydride, and 2.0 g (24 mmol) pyridine was stirred in a 50 ml RB flask under air in a 120° C. oil bath for 5 hrs. IR of a sample showed the absence of OH at 3,400-3,500 cm −1 as well as a strong 1,720 cm −1 ester peak. [0089] The mixture was added to 30 ml water containing 1 g sodium carbonate and stirred for 30 mins. followed by extraction with 50 ml diethyl ether. The ether layer was separated and washed with 10 ml water containing 1 ml concentrated HCl, separated again, washed with 5 ml 5% aqueous sodium bicarbonate, and dried over magnesium sulfate. The ether was filtered, and 5 mg MEHQ was added to the filtrate. The solution was quickly rotovapped from hot water and then held under 20 mm Hg vacuum overnight with an air bleed through a syringe needle to yield 4.25 g bisphenyl A bis(2-hydroxypropyl ether) dimethacrylate (“BPA POMA”). [0090] NMR (CDCl 3 ) indicated 85-90% conversion to methacrylate diester by ratio of aromatic ring protons (7.10 ppm) to methacrylate vinyl protons (6.08 ppm). Example 11 SBID POMA/TEGDMA—Glass Composition [0091] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch from Example 5 and 1.25 g SBID POMA from Example 9 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hr. and then in an oven at 50° C. under 17″ vacuum (330 mm Hg) with an air bleed for 8 hr. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described in Example 6. Example 12 BPA POMA/TEGDMA—Glass Compostion [0092] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch from Example 5 and 1.25 g BPA POMA from Example 10 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hr. and then in an oven at 50° C. under 17″ vacuum (330 mm Hg) with an air bleed for 8 hr. This composition contained 25.0 wt % resins, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described in Example 6. Example 13 [0093] Physical tests were performed on the SBID POMA/TEGDMA bars from Example 11 and the BPA POMA/TEGDMA bars from Example 12 as described in Example 6. [0094] As seen in Table 2, use of the bulky monomer with the spirobisindane structure reduced polymerization shrinkage by 15% relative to the bisphenyl A monomer control composition without significantly compromising mechanical properties. TABLE 2 Resin Mixture BPA POMA/ SBID POMA/ (1:1) TEGDMA TEGDMA Shrinkage, % 4.86 4.13 K IC , MPa · m 1/2 1.67 1.56 Flex Strength, 138 102 MPa · m 1/2

The invention relates to a dental composite material wherein space-filling compounds are utilized to reduce shrinkage upon polymerization; the invention also relates to a method for producing dental restoration articles with reduced shrinkage; the invention also relates to various dental restorative articles comprising the aforementioned space-filling compounds.

BACKGROUND OF THE INVENTION I. Field of the Invention The present invention provides novel organic compounds, useful for antifertility purposes. Particularly, the present invention provides a novel polypeptide isolated from the mammalian pineal gland. More particularly, there is provided a novel bovine pineal tripeptide and salts thereof with antigonadotrophic activity. Also provided by the present invention are novel methods for isolation of a bovine pineal tripeptide from the bovine pineal gland. Gonadotropins are a class of substances which stimulate male and female gonads, thus ordinarily representing profertility or fertility-maintaining agents. The gonadotropins include luteinizing hormone (LH) which stimulates ovulation and post-ovulatory progesterone production in the female ovaries. Another gonadotropin, follicle stimulating hormone (FSH), is a secondary pituitary hormone which stimulates the pre-ovulatory maturation of the Graafian follicles of the ovary, thus encouraging estrogen production therein. Thus, both LH and FSH stimulate estrogen or progesterone production and release from the ovaries, and are thereby essential for the establishment and maintenance of fertility. In the male, FSH supports the germinal cells of the testes, while LH stimulates testosterone production. Hence these gonadotropins are essential to spermatogenesis and thus fertility in the male. In addition to LH and FSH an hormonal substance from the hypothalamus, gonadotropin releasing hormone (GnRH), is known to be an endogenous agent for the stimulation of LH and FSH release. This substance is alternately known as LH-RH (luteinizing hormone releasing hormone) or LRF (luteinizing hormone releasing factor). Because the gonadotropins are essential to the maintenance of fertility in both the male and the female, antigonadotrophic substances have been sought for use as antifertility or fertility-suppressing agents. One fruitful source of antigonadotrophic substances has been the mammalian pineal gland, from which two broad classes of antigonadotrophic compounds have been isolated: polypeptides and indoles. With regard to the latter class, the most widely examined antigonadotrophic substance is melatonin, which, inter alia, reduces the effects of MSH (melanocyte stimulating hormone). Other pineal-derived antigonadotrophic indoles include serotonin, 5-hydroxytryptophol, 5-methoxytroptophol, and N-acetylserotonin. With regard to pineal antigonadotrophic polypeptides, one important such substance is arginine vasotocin, which was first isolated by Milcu, S.M., et al., Endocrinology 72:563-566 (1963). For the structure of arginine vasotocin, see Cheesman, Biochim. Biophys. Acta. 207:247-253 (1970) and German offenlegungsschrift 2,739,492, published Mar. 3, 1978 (Derwent Farmdoc CPI No. 18163A). Various other pineal antigonadotrophic polypepetides have been reported by various workers. For a brief review of reports of such polypepetides, see Table 3 (pages 164-166 of Reiter, Russell J., et al., "Pineal Antigonadotrophic Substances: Polypeptides and Indoles", Life Sciences 21:159-172 (1977). A further review of pineal antigonadotrophic polypeptides, particularly a disclosure of certain uncharacterized (e.g., no amino acid content or amino acid sequence) polypepetides is provided by Orts, R.J., et al., "Antifertility Properties of Bovine Pineal Extracts: Reduction of Ovulation and Pre-Ovulatory Luteinizing Hormone in the Rat", Acta. Endocrinologica. 85:255-234 (1977), and Orts, R.G., "Reduction of Serum LH and Testosterone in Male Rats by a Partially Purified Bovine Pineal Extract", Biology of Reproduction 16:249-254 (1977). II. Prior Art The existence of pineal antigonadotrophic polypeptides and their antifertility properties is known in the art. See Orts, R.J., et al., "Antifertility Properties of Bovine Pineal Extracts: Reduction of Ovulation and Pre-Ovulatory Luteinizing Hormone in the Rat", Acta Endrocrinologica. 85:225-234 (1977), and Orts, R.J., "Reduction of Serum LH and Testosterone in Male Rats by a Partially Purified Bovine Pineal Extract", Biology of Reproduction 16:249-254 (1977). Moreover, a general review of both polypeptide-type and indole-type pineal anti-genadotrophic substances is provided by Reiter, Russell J., et al., "Pineal Antigonadotrophic Substances: Polypeptides and Indoles", Life Sciences 21:159-172 (1977), cited above. SUMMARY OF THE INVENTION The present invention provides novel compositions of matter. In particular, the present invention provides a novel composition of matter consisting essentially of a pineal antigonadotrophic polypeptide. The present invention further provides novel methods for the isolation of a pineal antigonadotrophic polypeptide substantially free from all other pineal-derived substances. Most particularly, the present invention provides: (a) a bovine pineal antigonadotrophic polypeptide, being substantially free from all other pineal-derived substances, which is characterized by the amino acid sequence: threonine-serine-lysine; and (b) the pharmacologically acceptable carboxy salts and acid addition salts of the tripeptide characterized by the amino acid sequence: threonine-serine-lysine. The carboxyl-terminated residue of the bovine pineal antiqonatrophic tripeptide is lysine and the N-terminus is threonine. The bovine pineal antigonadotrophic tripeptide of the present invention is prepared by a novel process, described in detail by Example 1 hereafter, which comprises a further aspect of the present invention. Because of the purity and homogeneity of the bovine pineal antigonadotrophic tripeptide in accordance with the present invention, it represents a surprisingly and unexpectedly improved antifertility agent, as compared with previously known bovine pineal antigonadotrophic polypeptide compositions. Thus, while the novel bovine pineal antigonadotrophic tripeptide is useful for the same antigonadotrophic (therefore antifertility) purposes as the prior art compositions, smaller dosages and fewer untoward side effects are evidenced when the novel compositions are employed for pharmaceutical purposes. Even more strikingly, the provision of a single and strikingly active tripeptide in accordance with the present invention advantageously permits the chemical synthesis of the tripeptide from its amino acid constituents. Such a chemical synthesis is readily accomplished by methods known in the art. Thus, the present invention permits the induction of antifertility effects of the bovine pineal antigonadotrophic polypeptide factors to be made widely available without reliance on the comparatively tedious and uneconomic procedure of extraction from mammalian sources. The novel pineal antigonadotrophic tripeptides in accordance with the present invention are employed whenever the induction of an antigonadotrophic effect is indicated. While, as indicated above, such antigonadotrophic effects are typically antifertility effects, the present invention also provides for antigonadotrophic effects which are essentially pro-fertility (e.g., estrous regulation in non-primates), or merely secondarily related to fertility (e.g., management of steroid-supported carcinoma). The bovine pineal antigonadotrophic tripeptides of the present invention are useful in both humans and valuable domestic animals, including zoological specimens. The dosages employed are those wherein effective suppression of gonadotrophic hormones is achieved. The actual suppression of the gonadotropins is readily determined in any patient or animal by measuring changes in serum levels of these hormones, by known (e.g., radioimmunoassay) techniques. While the effective dose for a particular patient or an animal will depend upon the species, sex, age, indication, and condition of the subject, ordinarily an acute dosage of between 1 and 1,000 ng/kg, intravenously, is effective to suppress gonadotrophic activity. In those indications where sustained depression of gonadotrophic activity is required, subsequent and periodic doses of the bovine pineal antigonadotrophic tripeptides are administered. The precise regimen for administration can be readily adjusted for any patient or animal based upon serum levels of gonadotrophic hormones or subjective indices of response. The pineal antigonadotrophic tripeptides are administered by any convenient route of administration (e.g., subcutaneously, intramuscularly, vaginally bucally, intranasally, or orally) with equivalent dosages to those referred to above for intravenous administration. Equivalent dosages refer to those dosages by such other routes of administration as provides equivalent systemic (e.g., serum) levels of the tripeptide and equivalent suppression of gonadotrophic hormones. Accordingly routes of administration other than intravenous ordinarily require substantially increased dosages of the tripeptide. For example, the intramuscular dose will range from 2 to 10 times the intravenous dose, while the oral dose will in most cases be significantly higher than the intramuscular dose. In any case the appropriate equivalent dosage is determined by patient or animal response (i.e., gonadotropin suppression). For the various routes of administration, conventional dosage forms are employed. Accordingly, sterile solutions are employed where parenteral administration is selected, while suppositories are conveniently used when vaginal or rectal routes of administration are selected. When oral routes of administraton are selected, enteric-coated tablets or capsules will represent a preferred dosage form in those cases where variations in gastric pH would create unpredictability in the rate of tripeptide absorbed versus the rate of gastric hydrolysis. Regarding the indications for use of the novel bovine pineal tripeptides in mammalian males, administration of an antigonadotrophic amount results in a significant reduction of or cessation of spermatogenesis, thereby abolishing male fertility. Since the effect on spermatogenesis is accompanied by a decrease in testosterone levels, supplemental androgenic steroid therapy may be indicated to restore libido. However, in those patients and animals where diminished libido and the associated behavioral changes are a desirable additional effect of the tripeptide, no additional androgenic steroid therapy is indicated. Patients within the latter category would include those in certain institutions (e.g., prisons and mental hospitals), while animals within the latter category would include canine and feline species where the effect of the tripeptide would be tantamount to a reversible castration. Since an effective male antispermatogenic or antifertility agent requires that drug be delivered chronically, one preferred method of administration for this and other chronic indications is by a prolonged-release formulation or a prolonged-release device. Many such devices, e.g., comprising a drug reservoir surrounded by a controlled release rate membrane, are applicable for the chronic and controlled release of the novel bovine pineal antigonadotrophic polypeptides of the present invention. A second preferred method for chronic administration is in the food or feed of the patient or animal being treated. In female mammals, suppression of gonadotrophic hormones is effective to (1) prevent ovulation, and (2) reverse any CL progesterone-supported pregnancy. With regard to the first of these uses, suppression of ovulation in humans is accomplished by administering the novel pineal antigonadotrophic tripeptide from the time of menses to about three weeks after the initiation of the menses. In estrous-cycling animals the novel pineal antigonadotrophic tripeptides are administered chronically to prevent ovulation. With regard to the reversal of CL-supported pregnancy, in those animals where a functioning corpus luteum (CL) is required for the maintenance of pregnancy, the administration of the novel pineal antigonadotrophic tripeptide after conception will either prevent implantation or reverse fetal implants, thereby reversing early pregnancy. For this purpose, the pineal antigonadotrophic tripeptide is given, for example, in humans over several days, beginning prior to the next anticipated menses. In non-primates the time initiation of treatment ranges from immediately post-conception to midterm and continues over several days. In estrous-cycling mammals, the novel pineal antigonatrophic tripeptide is useful in the regulation or synchronization of the estrous cycle, by regression of the corpus luteum. For this purpose, the timing during the estrous cycle of the pineal antigonadotrophic tripeptide administration is similar to that employed by other corpus luteum-regressing or luteolytic agents (e.g., the prostaglandins). Thus in the polyestrous animal the treatment is continued for about one-half of a single cycling period and ovulation will then occur at a predetermined time thereafter. In addition to the pro-fertility effects of estrous regulation, mammals infertile because of a persistent corpus luteum may also be brought into estrus and successfully bred after treatment with the pineal antigonadotrophic tripeptides of the present invention. In addition to the various fertility-related indications recited above, certain other non-fertility uses of the pineal antigonadotrophic tripeptides include the treatment of precocial puberty, and steroid-supported carcinoma. These disease states, which often require the removal of the gonadotropin-producing gland (pituitary) or the gonads themselves, are thus non-surgically treated in accordance with the present invention. In those cases where sustained supression of gonadal function is desired (e.g., steroid-supported carcinoma of the breast or prostrate), the prolonged-release formulations or devices described above are employed. As indicated above, any of the various pharmacologically acceptable carboxy salts or acid addition salts of Thr-Ser-Lys are used in accordance with the present invention. These salts are respectively prepared from the tripeptide of Example 1, below, by mixture with a dilute solution of the base or acid corresponding to the carboxy or acid addition salt to be prepared. Thereafter the salts are recovered in solid form by conventional techniques, i.e., concentration under reduced pressure. Among the pharmacologically acceptable carboxy salts in accordance with the present invention are various metal salts, including alkali and alkaline metal salts, and heavy metal salts. Also, amine salts, including primary and secondary and tertiary amine salts, are included, as well as the quaternary ammonium salts. With regard to the acid addition salts, there are included conventionally employed acid salts of pharmaceuticals, such as the hydrochloride and hydrobromide salts. As is apparent, however, from the above list, suitable salts for use in accordance with the present invention are characterized only by the absence of substantial toxicity and suitability for pharmaceutical formulation. DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 Threonine-serine-lysine from the bovine pineal gland A. Fresh bovine pineal glands (120 g) are lyophilized and thereafter homogenized in acetone (100 ml) with stirring for 4 hr at 4° C. The resulting residue is then filtered, washed with acetone (20 ml) and concentrated under reduced pressure at 55° C. The resulting powder is then dispersed in 2.0 N acetic acid (30 ml) and stirred for one hr at ambient temperature. Thereafter the resulting acetic acid mixture is centrifuged at 16,300 g for 2 hr and the supernatant collected and lyophilized. This residue is then dissolved in glacial acetic acid (20 ml), stirred for 45 min at ambient temperature, and centrifuged at 12,000 g for 30 min. Thereafter the supernatant is diluted with distilled water (50 ml) and lyophilized. The resulting residue is then dissolved in 1.0 N acetic acid (10 ml) and centrifuged at 48,200 g for one hr. B. Following the above mild acid extractions, the final supernatant of Part A is lyophilized and the residue dissolved in 0.06 M acetic acid (3 ml of acid per 100 g of residue), pH 3.0, and placed on a column (30 cm×1.5 cm) of analytical grade polystyrene cation exchange resin, Dowex 50[H+], prewashed successively with 2 N sodium hydroxide, distilled water, 2 N hydrochloric acid, and distilled water. Elution successively with water (75 ml), 0.2 M aqueous pyridine (pH 4.0, 75 ml), 0.2 M pyridine (pH 5.0, 150 ml) and 1 M pyridine (pH 7.5-8.5, 75 ml) yields in the 1 M pyridine fractions a product which is collected and lyophilized. The resulting residue is then dissolved in 1% aqueous ammonium bicarbonate (NH 4 HCO 3 ) and placed on a column (80 cm×1.5 cm) of cross-linked dextran gel (Sephadex G25 Fine), equilibrated with 1% aqueous ammonium bicarbonate at ambient temperature. Elution of a column with 1% aqueous ammonium bicarbonate at a flow rate of 45 ml/hr, collecting 4 ml fractions, yields a crude product A in fractions 30-36. This crude product is then lyophilized and the residue dissolved in water. C. The aqueous mixture of Part B is then further purified by vertical flow paper electrophoresis. The crude product in the aqueous mixture is spotted on the paper and run for 30 min at 3,000 v in a mixture of pyridine, acetic acid, and water (100:4:900), pH 6.5. In fraction 4 (of 16 fractions running from cathode to anode), the R L is 0.77-0.83 wherein R L is the ratio of the migration distance of the fraction of interest to that of lysine during the vertical paper electrophoresis. This fraction is then eluted with water and subsequently lyophilized. D. The residue of Part C is then dissolved in water and further purified by descending paper chromatography for 10 hr using butanol, acetic acid, and water (5:1:4) as a solvent system and 3 mm Whatman chromatography paper. From this chromatogram, a fraction whose R f is 0.15-0.22 is eluted and lyophilized. The resulting residue provides the bovine pineal antigonadotrophic tripeptide threonine-serine-lysine substantially free from all other pineal-derived substances. E. The amino acid sequence of the tripeptide of Part D is determined by the Edman degradation procedure described by Salnikow, J., et al., J. Biol. Chem. 248:1480. EXAMPLE 2 Effects of threonine-serine-lysine on mammalian species A. Compensatory Ovarian Hypertrophy (COH) is an effect in standard laboratory (mammalian) animals for assessing antigonadotrophic activity by determining the increase in weight of the remaining gonad after unilateral gonadectomy. Procedures for COH measurement in female rats are described in Ramirez, V.D., et al., Endocrinology 95:475 (1974). According to these known procedures threonine-serine-lysine, prepared in Example 1, is administered intraperitoneally to adult female mice on the same day as a unilateral ovariectomy is performed. On day 5, both experimental and control animals are sacrificed and mean ovarian weights are obtained. The results of this study, reported in Table I below, indicate that the COH or compensatory ovarian hypertrophy (i.e., the difference in ovarian weights as a percentage of the weight of the gonadectomized ovary) is reduced in a dose-dependent manner in animals treated with the threonine-serine-lysine. TABLE I______________________________________Reduction of Compensatory Ovarian HypertrophyDose (ng) COH (± SE)______________________________________Control 45.5 ± 5.3186.1 34.6 ± 6.8372.2 11.1 ± 15.1______________________________________ B. The effect of threonine-serine-lysine on serum concentrations of FSH in the adult female rat is measured 24 hr after intraperitoneal injection of threonine-serine-lysine to unilaterally ovariectomized mice. On day 5 after injection, the animals were sacrificed and ovarian weights recorded There are then determined compensatory ovarian hypertrophy (5 days after treatment) as well as the serum FSH (24 hr after treatment). The results of this study are reported in Table II below. TABLE II______________________________________Effect of Threonine-Serine-Lysineon Compensatory Ovarian Hypertrophyand Serum FSH in Female MiceNo. ofanimals Dose (ng) COH (± SE) Serum FSH (± SE) ng/ml______________________________________6 Control 29.7 ± 8.4 296.8 ± 3758 35.1 12.6 ± 10.9 254.4 ± 88.78 70.3 21.9 ± 8.0 377.0 ± 56.98 175.7 12.9 ± 5.0 165.0 ± 22.58 351.7 21.1 ± 7.8 179.0 ± 60.9______________________________________ C. The antifertility effects of threonine-serine-lysine on the male rat are measured by their ability to inhibit GnRH-or gonadotropin releasing hormone-induced rise in FSH when threonine-serine-lysine is administered intravenously. In this test, both control and tripeptide-treated animals received GnRH in a phosphate buffered saline solution, followed by the administration of the tripeptide in the same buffer. Five animals each were in one control and three tripeptide-treated groups, with the results reported in Table III indicating FSH suppression. TABLE III__________________________________________________________________________Reduction of Serum FSH in GnRH-treated Maleby Threonine-Serine-Lysine Mean concentration of plasma FSH (ng/ml ± SE) ng/mlDose (ng) 0 min 15 min 30 min 60 min__________________________________________________________________________Control 362.5 ± 20.7 1753.4 ± 450.6 1701.6 ± 720.6 247.8 ± 14.01.48 302.2 ± 26.2 338.4 ± 38.8 592.5 ± 217.6 586.5 ± 301.314.8 45.6 ± 52.3 402.9 ± 117.7 472.7 ± 76.9 684.5 ± 142.0148 43.9 ± 85.6 646.1 ± 198.0 1407.8 ± 499.6 1279.6 ± 180.8__________________________________________________________________________

The present invention relates to a bovine pineal tripeptide, exhibiting the amino acid sequence: Thr--Ser--Lys wherein Thr is threonine, Ser is serine and Lys is lysine, and pharmacologically acceptable carboxy and acid addition salts thereof. The invention provides for the isolation of this tripeptide substantially free from all other pineal gland substances, including the various pharmacologically active pineal indoles and polypeptides. Also provided are methods for using this bovine pineal tripeptide for antifertility purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of U.S. patent application titled “Game Machine,” Ser. No. 08/919,016, filed Aug. 27, 1997, pending, the contents of which are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates to the field of game machines, and more particularly to the field of game machines such as slot machines in which unusual lighting, sounds, or any other similar indicator signals that a player may most likely win a prize. BACKGROUND Game machines, such as slot machines and poker game machines, that pay back tokens, such as coins, for winning game results have been very popular. Here, slot machines will be used as an example of a game machine. Players start a game by pulling a start lever after putting a token in the slot machine. A plurality (three, for example) of reels with numerous types of symbols arranged on the circumference rotate at high speed in the slot machine, and the prize status is determined by the combination of the symbols on the reels displayed at a given location in a window when the reels have stopped. The number of tokens that are paid out is determined by the combination of symbols when the reels have stopped, that is, the prize status. When the current game prize status has been determined, the reels are rotated to begin the game. Slot machine prizes typically include “Big Jackpots,” where 1000 or more tokens, for example, are paid back, as well as “Small Jackpots,” where less than 1000 tokens are paid back. A variety of other prizes also may be offered. In most slot machines, the player can operate stop buttons provided in the slot machine to stop the reels, but in the type of slot machine in which the prize status is determined by random selection using random numbers for each game, the reels are not stopped immediately when the player actuates the stop buttons, but instead are stopped when the symbols on the reels reach the position corresponding to the prize status previously determined by random selection. It is possible for too much time to pass after the player presses the stop buttons until the reels stop at the prize status that had been previously determined by random selection. This could lead to unnatural reel-stopping operations. In such cases, the reels may be stopped at a point that does not match the prize status previously determined by random selection. In other words, when too much time passes until the reels stop after the player has operated the stop bottons, leading to unnatural reel-stopping operations, the reels are stopped irrespective of the prize status previously determined by random selection. As a result, even when the prize status previously determined by random selection would have been, for example, a “Big Jackpot,” the prize status may end up being a “Lose” due to the timing with which the player has actuated the stop buttons. Conversely, when the prize status previously determined by random selection would have been a “Lose,” the prize status may end up being a “Big Jackpot” due to the circumstances under which the player actuated the stop buttons. Slot machine prizes also may include a so-called “Second Game Win” result, where a second game can be played as a subsidiary game. This “Second Game Win” result is described below. The game that results in the aforementioned “Big Jackpot,” “Small Jackpot,” or “Second Game Win” is referred to herein as the first game. When a “Second Game Win” is won in a first game, a second game can be played without new tokens being entered. The second game is played with an arrangement or a set of beginning reels that is different from the arrangement or set of the first game. Common examples are referred to as “Bonus” games or “Free” games. Such a second game is often advantageous for the player, allowing the player to win a prize that includes a large amount of tokens depending on the results of the second game. The player plays the slot machine in anticipation of increasing the number of tokens in possession, but since the number of tokens in the player's possession does not increase all that much with “Small Jackpots,” the player plays the slot machine while hoping for a “Second Game Win” or a “Big Jackpot” that will quickly increase the number of tokens in the player's possession. Frequently, the prize status in a slot machine is determined by random selection using random numbers for each game. In this type of slot machine, for example, the prize status is randomly selected when a token is put into the slot machine and the start lever is pulled, and the current game prize status is then determined. When the current game prize status has been determined, the reels are rotated to begin the game. However, in the type of slot machine in which the prize status is determined by random selection using random numbers for each game, the prize status is randomly selected when a token has been put into the slot machine and the start lever has been pulled, so the prize status of the current game is already known when the reels begin to rotate. As described above, the player plays slot machines hoping for a “Second Game Win” or “Big Jackpot” to quickly increase the number of tokens in the player's possession, and when it is known that there is an extremely high possibility that the current game will result in a “Big Jackpot” or “Second Game Win” as a result of previous random selection (as described previously, there can be cases in which the prize status might end up as a “Lose” due to the timing with which the player actuates the stop buttons), it would be extremely significant to make a demonstration alerting the player to that fact. SUMMARY OF THE INVENTION The systems and methods described herein are designed to provide a game machine which can make demonstrations when a “Second Game Win” has been obtained by random selection for determining the game prize status, and which can make more effective demonstrations when a “Second Game Win” has been obtained. A game machine according to the systems and methods described herein randomly selects the game result conditions of a first game by lottery from among a plurality of conditions, and determines the game results on the basis of the randomly selected results, wherein the game machine is characterized by alerting a player by a demonstration to the fact that there is “Second Game Win” condition among the randomly selected conditions. The presentation includes various states or features, such as changes in the rotating operation of the reels, visual stimulation by special light displays, audio stimulation by special sounds, and tactile stimulation by vibrations in the operating components of the machine. Naturally, two or more states or features can be combined. A game machine according to the systems and methods described herein includes random selection means for randomly selecting, at the beginning of the current first game, game result conditions for a predetermined prescribed number of games from among the plurality of such conditions, storage means for storing a prescribed number of game result conditions; actuating means for actuating the start of a game, determination means for determining whether or not a “Second Game Win” condition is present among the randomly selected results for a prescribed number of games, and demonstration means for displaying prescribed sensory information to the player when the “Second Game Win” condition is present. This sensory information may include visual, audio, and tactile information, either independently or in combination, similar to that described above. A game machine optionally may include second random selection means for randomly selecting in advance several kinds of current game result conditions at the beginning of the current first game, selecting one of the several kinds of randomly selected results by a prescribed method, and actualizing the current game results, wherein a demonstration is made during the current game when the aforementioned “Second Game Win” condition is present among the several kinds of conditions randomly selected in advance. Optionally, a demonstration may be made when the randomly selected game results include at least two predetermined game results, or some combination of predetermined game results. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the appearance of a slot machine in an embodiment of the present invention. FIG. 2 is a detail of the window for viewing the reels of the slot machine depicted in FIG. 1 . FIG. 3 is a flow chart of the process for determining active prize lines. FIG. 4 is a flow chart of the basic game progress of a slot machine according to the present invention. FIG. 5 is a flow chart of the process from the determination of the prize to the pay out of tokens. FIG. 6 is a block diagram depicting a microcomputer controlling a slot machine according to the present invention. FIG. 7 is a flow chart describing the operation of a slot machine in an embodiment of the present invention. FIG. 8 is an illustration of the structure of the random number store in an embodiment of the present invention. FIG. 9 is a flow chart of the operation of the slot machine in another embodiment of the present invention. FIG. 10 illustrates the structure of the random number store in another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In conventional types of slot machines in which the prize status is determined by random selection using random numbers for each game, when the prize status resulting from random selection in the current game is a “Big Jackpot,” a demonstration is made by unusual operations, such as unusual lights or sounds, but there is no demonstration when the prize status resulting from the random selection in the current game is a “Second Game Win.” In the conventional slot machines described above, the results are randomly selected using random numbers for each game, so only the current game prize status is known. Thus, demonstrations are made only when the randomly selected result of the current game is a “Big Jackpot,” and there are a fewer number of demonstrations when there are “Big Jackpots.” There is thus a problem in that the demonstrations are not very effective in arousing the interest of the player to play more games. The present invention is described below with reference to the drawings. Here, a slot machine is described as an example of a game machine according to the present invention. However, the present invention is not limited to slot machines, and may be used for any type of game machine in which game results can be randomly selected. FIG. 1 illustrates the appearance of a slot machine in an embodiment of the present invention. The slot machine in FIG. 1 includes a main unit 1 . A cabinet 2 having a front face constituting the entire main unit 1 is provided with windows 3 L, 3 C, 3 R corresponding to a plurality of reels 4 L, 4 C, 4 R, (three in the case of FIG. 1 ), for viewing the symbols on each of the reels 4 L, 4 C, 4 R located inside the cabinet 2 . A speaker 16 and one or more lights 18 is included on a display panel 15 , or may be placed elsewhere on the main unit 1 . Changes in the tone, volume or nature of the sounds may be broadcast through speaker 16 , or changes in the color or timing of the light 18 , or some combination thereof, may be used to demonstrate the prize status, i.e., the likelihood of winning a prize, to the player. Alternatively, static or moving text, numbers, or designs could be illuminated in a portion of the display panel 15 or on the main unit to indicate to the player that there is an increased likelihood of winning a “Big Jackpot”. A start lever 5 for rotating the reels 4 L, 4 C, 4 R when operated by a player is rotatably attached at a prescribed angle on a side face of the cabinet 2 . A token inlet 6 for entering tokens and a digital display 7 , comprising a credit number display 7 A for displaying the number of tokens currently credited and a prize number display 7 B for displaying the number of tokens won in the current game, are provided on the lower right side of the windows 3 L, 3 C, 3 R on the front face of the cabinet 2 . Arranged below the windows 3 L, 3 C, 3 R on the front face of the cabinet 2 are a spin switch 8 for setting the reels 4 L, 4 R, 4 C in motion by the operation of a push button which is separate from the operation of the start lever 5 , a single bet switch 9 for betting just one token from among the credited tokens on the game when the push button is pressed once, a maximum bet switch 10 allowing the maximum possible number of tokens to be bet on a single game when the push button is pressed once, a “C/P” switch 11 for switching between play credit/pay out of the tokens won by the player when the push button is pressed, and a token receptacle 13 for receiving tokens paid out from a token pay outlet 12 at the bottom of the front face when the “C/P” switch 11 is switched. FIG. 2 is a detailed view of the window for viewing the reels 4 L, 4 R, 4 C of the slot machine depicted in FIG. 1 . In this example of a slot machine, the number of prize lines can be selected according to the number of tokens entered (number of tokens bet on the game) prior to the start of the game. That is, in FIG. 2, three symbols “S” on each reel can be seen through the windows 3 L, 3 C, 3 R. When one token is entered, only a single line 21 is activated per prize determination; when two tokens are entered, a total of three lines comprising lines 21 , 22 A, and 22 B are activated per prize determination; and when three tokens are entered, a total of five lines comprising lines 21 , 22 A, 22 B, 23 A, and 23 B are activated. In FIG. 2, a set of lamps 14 a , 14 b , 14 c , 14 b′ , 14 c′ , which are marked with the characters “1”, “2”, and “3”, lights up to display the lines that have been activated according to the number of tokens entered. The selection of the number of active lines is determined, for example, by the number of tokens entered prior to the operation of the start lever 5 or the spin switch 8 . The display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are connected so as to light up to display the lines that have been activated according to the number of tokens entered. Thus, the selection of the number of active lines is determined by the number of tokens entered prior to the operation of either the start lever 5 or the spin switch 8 , or, alternatively, by the number of tokens entered after the operation of the start lever 5 and prior to the operation of the spin switch 8 . When one token is entered, only one line, which is associated with one display lamp 14 a and mark “1”, is activated per prize determination; when two tokens are entered, a total of three lines, which are associated with three display lamps 14 a , 14 b , 14 b ′ and the marks “1” and “2” are activated per prize determination; and when three tokens are entered, a total of five lines, which are associated with all five of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ and with the marks “1”, “2” and “3”, are activated. This selection is done in accordance with the flowchart shown in FIG. 3 . The selection of the number of active lines may be based on a microswitch, photosensor, or other such electrical signal-based device for detection of the insertion of a token and the determination as to whether or not the start lever 5 or spin switch 8 has been operated. In the “active line” process in FIG. 3, one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are turned on, and at the same time, a signal is input to the microcomputer described below so as to be taken into account during the determination of the prize. FIG. 3 is a flowchart 100 illustrating the selection of lines to activate by lighting up one or more of the lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′. The selection may be made using a microswitch, a photosensor, or another similar electrical signal-based system for detection of the insertion of a token and determination as to whether or not the start lever 5 , or the spin switch 8 , or both, have been operated. In the flowchart 100 , the line activation process starts at a step 101 indicating conclusion of a prior game. Following the step 101 is a test step 102 that determines whether a token has been entered. The test step 102 is repeated until a token is entered. Once a token has been entered, control passes to a step 104 so that a single display lamp 14 a will be lit to activate a single line, which is marked with a “1” in FIG. 1 . Following the step 104 is a test step 106 that determines whether the start lever 5 has been pulled. If the start lever 5 has been pulled, then the game proceeds to a game start step 120 and the game starts. Otherwise, a test step 108 determines whether a second token has been entered. The test steps 106 , 108 are repeated until either the start lever 5 is pulled or a second token is entered. If a second token is entered, control passes to a step 110 that indicates that two more lamps 14 b , 14 b ′ will be lit to activate two more lines, which are marked with a “2” in FIG. 1, for a total of three lines activated. Following the step 110 , a test step 112 is performed to test whether the start lever 5 has been pulled. If the start lever 5 has been pulled, control passes from the step 112 to the game start step 120 . Otherwise, a test step 114 is performed to determine whether a third token has been entered. The steps 112 , 114 are repeated until either the lever 5 is pulled or a third token is entered. If a third token is entered, two more display lamps 14 c , 14 c ′, which are marked with a “3” in FIG. 1, will be lit to activate two more lines, for a total of five lines activated. A test step 118 is then performed to determine whether the start lever 5 has been pulled. If the start lever 5 has been pulled, then control passes to the game start step 120 . Otherwise, the test step 118 is repeated. In the “active line” process shown in FIG. 3, one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are turned on depending on the number of tokens entered, and, at the same time, a signal is input to the microcomputer, as described below, so that the number of token entered is taken into account during the determination of the prize. After the number of prize lines has thus been determined, the game basically progresses according to the flow chart in FIG. 4 . That is, the game starts when the start lever 5 or spin switch 8 is operated, the three reels rotate, the prize status described below is randomly selected after a prescribed period of time has passed, the reels automatically stop based on the randomly selected results, and the current game is terminated. FIG. 4 is a flowchart 200 illustrating progress of the game once the number of prize lines has been determined in accordance with the process shown in FIG. 3 (or by following one of a variety of conventional processes equivalent to that shown in FIG. 3 ). The game begins at the game start step 120 (of FIG. 3 ). A reel rotation step 202 follows the start step 120 . Following the reel rotation step 202 is a delay step 204 . Following the delay step 204 is a result selection step 206 in which the results for a plurality of games are randomly selected to provide a random selection of prize status. Following the result selection step 206 is a reels stop step 221 in which the reels are stopped, optionally in response to a player's pressing of stop buttons. After the step 221 , control passes to a game end step 224 . When the game is over, the process for determining the prize is carried out according to the flow chart in FIG. 5, for example, and tokens are paid out when a prize has been won. During the determination of a prize, photoelectric signal components provided for the symbols on the reels are read by photosensors, for example, or signal components may be provided at locations on the reels so that reset pulses are obtained for each reel rotation by pulse motors that drive the reels, allowing it to be determined whether a pulse signal has been supplied for any pulse to the pulse motor until the reels are stopped following the production of the reset pulse. FIG. 5 is a flowchart 300 illustrating the determination of the prize when the game is over. Following the game end step 224 (of FIG. 4 ), control passes to a step 312 in which determination of the prize is made. Following the step 312 is a test step 314 which tests whether a prize was won. If so, control passes to a step 316 . Otherwise, control passes to the game over step 101 (of FIG. 3 ). In the step 316 , the prize tokens are paid out in the proper amount. Following the step 316 is a test step 318 in which it is determined whether the paying out has been completed. If so, control passes to the game over step 101 . Otherwise, control returns to the step 316 and the process is repeated until the game over step 101 is reached. FIG. 6 is a block diagram depicting the microcomputer controlling the slot machine in the present embodiment. In FIG. 6, the broken line block A is a main control component having a main CPU 50 , a ROM 51 , and a RAM 52 . The ROM 51 stores a correspondence table of the symbols described above and symbol codes, a table of symbol codes corresponding to prizes and the number of prize tokens paid out, as well as prize probability tables and the like according to prize status when a prize is awarded for the game that has been run. The RAM 52 prepares random number stores for temporarily storing random numbers sampled after the start of a game, memory for temporarily storing data such as rotating reel code numbers and symbols, and the like. A clock pulse generator 53 generates, for example, a four MHZ pulse, and that actuates the main CPU 50 based on this standard pulse, and a divider 54 gives an interruption pulse of 500 Hz, for example, to the main CPU 50 for the interrupt execution process of a prescribed program. A sound generator 55 is driven so as to produce sounds by means of a speaker 56 in order to enhance game interest at prescribed periods after the start of the game. The speaker 56 can be used as the demonstration means described below. An LED drive component 57 drives a 7-segment digital display light-emitting diode 58 , for example. This diode 58 can be used to display the number of tokens paid out or the like. The broken line block B in FIG. 6 is a reel drive view block. In this embodiment, reels 4 L, 4 C, 4 R are driven by pulse motors 28 L, 28 C, 28 R. The motors 28 L, 28 C, 28 R are rotated by drive pulses from a motor drive component 60 . For example, the reels are rotated one reel symbol at a time, as seen through windows 3 L, 3 C, 3 R, per pulse. The reels are constructed in such a way that a reset signal is produced per rotation. The reset signals are detected by a detection block 61 . In the main CPU 50 , the reset signals are detected by the detection block 61 , and the number of drive pulses given to the motor is then counted, allowing the reel symbols visible in the windows 3 L, 3 C, 3 R to be specified. In the prize determination, the symbols of the reels are used as code signals as described above, and the combination is matched with the ROM described below. A prize token pay out hopper 70 and a hopper motor drive component 71 also are shown. A token detector 72 detects the insertion of tokens prior to the start of the game. When a prize has been won, the hopper motor for paying out prize tokens is driven to pay out the prize tokens. The tokens that are paid out are counted, for example, by the token counter 72 located in the token pay out chute, and the game is over when the prescribed number of tokens has been reached. The signal for the number of tokens paid out from the hopper 70 and the signal for the number of tokens entered from the token detector 72 are sent via a “Sw” input component 75 and main CPU 50 from a count drive component 76 to a counter or lamp 77 , the number of tokens entered or paid out is detected, or one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ for the active prize lines are lit up according to the number of tokens entered. The display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ can also be used as the demonstration means described below. When three tokens are entered, a lock solenoid 73 that locks the entered tokens is driven. Another switch operating component 78 , such as a stop switch or the like, is operated when a player wishes to stop a game after a token has been entered. A start signal generator 79 is constructed, for example, of the aforementioned start lever 5 or spin switch 8 . The system structure described above allows the determination process for the basic progress of the game shown in the flow charts above to be carried out by the prescribed executing program using the main CPU 50 . The method for randomly selecting the prize status and the method for determining whether or not a demonstration is to be put on, which are features of this embodiment, are described below. The prize status is randomly selected as a result of a match between the random number values sampled at the start of the game, as described above, and the groups of numerical values for awarding a prize which are stored in the prize table in the ROM. FIG. 7 is a flow chart describing the operation of the slot machine in the present embodiment. FIG. 8 is an illustration of the structure of the random number store in the present embodiment. FIG. 7 is a flowchart 400 describing one possible method of operation of the slot machine in an embodiment of the present invention and FIG. 8 is an illustration of the structure. Turning first to FIG. 7, the operation process begins at an all clear step 401 . Following the step 401 is a step 402 in which random numbers are sampled for four games and stored in a random number store (shown in FIG. 8 and described below). Following the step 402 is a game start step 404 in which the game starts. Following the step 404 is a test step 406 in which a test is made to determine whether a token has been entered. If so, control passes to a test step 408 . Otherwise, the test step 406 is repeated. In the test step 408 , it is determined whether the start lever 26 is on. If so, control passes to a test step 410 . The test steps 406 , 408 are repeated until either the start lever 26 is on or a token is entered. In the test step 410 , a determination is made whether there is a “Second Game Win” result. If so, control passes to a step 412 in which a demonstration flag is set, and, following the step 412 , control passes to a step 414 . Otherwise, control passes from the step 410 to the step 414 and thus the demonstration flag is not set. In the step 414 , a first random number is extracted from the random number store to determine the prize status. Following the step 414 is a step 416 in which the random numbers in the random number store are shifted, as described below. Following the step 416 is a step 418 in which a random number for one game is sampled. Following the step 418 is a step 420 in which the random number sampled in the step 418 is stored in the fourth random storage number area of the random number store. Following the step 420 is a test step 422 in which it is determined whether the demonstration flag is ON. If so, control passes to a step 424 in which reel rotation starts in a staggered manner. Otherwise, control passes to a step 426 in which reel rotation starts in a normal manner. Following each of the steps 424 , 426 is a step 428 , in which the demonstration flag is cleared when all reels stop rotating. Following the step 428 , control passes to the game over step 101 . When, for example, the main power source switch of the slot machine is turned on, or when a clear switch not shown in the figures is switched ON, the entire system is initialized, the random numbers stored in a random number store 80 shown in FIG. 8 are cleared, and the demonstration flag is cleared. As shown in FIG. 8, the random number store 80 has four random number areas: a first random number area 81 , a second random number area 82 , a third random number area 83 , and a fourth random number area 84 , in which the four random numbers comprising random number α, random number β, random number γ, and random number δ can be stored. The random number stored in the first random number area 81 is used in the random selection of the current game prize status, the random number stored in the second random number area 82 is used in the random selection of the prize status in the game following the current game, the random number stored in the third random number area 83 is used in the random selection of the prize status of the subsequent game, and the random number stored in the fourth random number area 84 is used in the random selection of the prize status in the game after that. That is, random numbers to be used up through the next three games from the current game are stored. To return to the flowchart 400 of FIG. 7, in the all clear step 401 , the entire system is initialized and the random numbers stored in the random number store 80 are cleared. Following the all clear step 401 is the step 402 in which random numbers for four games (a total of four random numbers) are sampled and the sampled random numbers are stored in the first, second, third and fourth areas 81 - 84 in the random number store 80 . Following the step 402 is the game start step 404 , where the main unit 10 of the slot machine is placed in game start mode. In the step 406 , it is determined whether a token has been inserted. In the step 408 , which occurs after a token has been inserted, it is determined whether the start lever 5 or the spin switch 8 has been pulled. When the start lever 5 has been actuated, it is determined at the test step 410 whether any of the four random numbers in the random number store 80 correspond to a “Second Game Win” condition. When there is no “Second Game Win” condition, the game proceeds to the step 414 . When there is a “Second Game Win” condition, a demonstration flag is set up in the step 412 . Alternatively, a different type of demonstration could be made depending on whether a different combination of game results, including, for example, a “Big Jackpot” and a “Second Game Win”, or a “Small Jackpot” and a “Second Game Win”, or a “Second Game Win” and a “One Shy” condition (which will be described below), or some variation thereof, was present in one or more of the areas in the random number store 80 . For example, a state in which there is no “Big Jackpot” because the symbol on one of the reels 4 L, 4 C, 4 R (three reels in the present embodiment) does not match (here, the state of two matches is called “One Shy”). (If four or more reels were used and all but two reels matched, then the state could be called “Two Shy”, and so on, depending on the number of reels used. For example, the condition of having all but a predetermined number of reels, or dice, or other similar type of game feature, match or correspond is referred to herein as a pseudo specific game result condition.) Alternatively, a different type of demonstration could be made depending on whether a “One Shy”, “Two Shy”, “Big Jackpot”, “Little Jackpot”, “Second Game Win,” multiple “Free” or “Bonus” games, or some combination or variation thereof, was present in one or more of the areas in the random number store 80 . In the step 414 , a random number is taken from the first random number area 81 in the random number store 80 . The random number thus taken is used for random selection of the current game prize status, and the current game prize status is determined. In the step 416 , the random number stored in the second random number area 82 is then moved to the first random number area 81 , the random number stored in the third random number area 83 is moved to the second random number area 82 , and the random number stored in the fourth random number area 84 is moved to the third random number area 83 . In the step 418 , a new random number to be stored in the fourth random number area 84 is then sampled. In the step 420 , the new random number is stored in the fourth random number area 84 . In the step 422 , the system checks to see whether or not the demonstration flag is ON, i.e., is set. When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 426 . When the demonstration flag is ON, the reels start rotating in a staggered manner (for example, the first reel 4 L is rotated, and a little while later the second and third reels 4 C, 4 R are rotated) in the step 424 . A demonstration may be made shortly after the reels begin to rotate. That is, a player may know there is no probability of a “Big Jackpot” or a “Second Game Win” when the reels start to rotate simultaneously, whereas a player may know that there is a probability of a “Big Jackpot” or a “Second Game Win” when the reels start rotating in a staggered manner, thereby giving the player greater hope. When all the reels are stopped, the demonstration flag is cleared in a clearing step 428 , and the game is over. The system subsequently returns to the game start step 404 at the start of the game, and the next game is begun. In the present embodiment, it is possible to determine the prize status, that is, the stopping position of all of the reels 4 L, 4 C, 4 R with one random number. However, the present invention is not limited to this embodiment, and a random number may be provided for each reel. To return to the description in FIG. 7, random numbers for four games (total of four random numbers) are sampled in the step 402 , the sampled random numbers are stored in the four random numbers areas 81 - 84 in the random number store 80 , and the slot machine is put in game start mode 404 . Whether or not a token has been inserted is then detected in the step 406 , and after a token has been inserted, whether or not the start lever 5 or the spin switch 8 has been pulled on is then detected in the step 408 . When the start lever 5 is on, the step 410 checks to see whether or not any of the four random numbers in the random number store 80 correspond to a “Second Game Win” state, that is, a prize allowing a second subsidiary game to be played. When there is no “Second Game Win” random number, the game proceeds to the step 414 , and when there is a “Second Game Win” random number, a demonstration flag is set up in the step 412 . In the step 414 , a random number is taken from the first random number area 81 in the random number store 80 , the random number thus taken is used for the random selection of the current game prize status, and the current game prize status is determined. The random number stored in the second random number area 82 of the random number store 80 is then moved to the first random number area 81 , the random number stored in the third random number area 83 is moved to the second random number area 82 , and the random number stored in the fourth random number area 84 is moved to the third random number area 83 in the step 416 . A new random number to be stored in the fourth random number area 84 of the random number store 80 is then sampled in the step 418 , and the new random number is then stored in the fourth random number area 84 in the step 420 . Here, the system checks to see whether or not the demonstration flag is ON, namely, is set in the step 422 . When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 426 , and when the demonstration flag is ON, the reels start rotating while staggered (for example, reel 4 L is rotated, and a little while later reels 4 C and 4 R are rotated) in the step 424 . In the present embodiment, a demonstration is made a little after the reels begin to rotate. That is, the player knows there is no probability of a “Second Game Win” when the reels start to rotate simultaneously, whereas the knowledge that there is a probability of a “Second Game Win” when the reels start rotating while staggered gives the player greater hope. When all the reels are stopped, the demonstration flag is cleared in the step 428 , and a second game is played if there is a “Second Game Win,” and the game is over when the second game is over. The system subsequently returns to the step 404 , and the next game is begun. When there is no “Second Game Win” in the step 410 , the demonstration flag is not set and the system subsequently returns to the step 404 without playing a second game, and the next game is played. Thus, a player must enter one or more tokens to play the next game if there is no “Second Game Win” in the step 410 . However, if there is a “Second Game Win”, the game machine will recognize that fact and the player will not be required to enter more tokens to play another game after the system reaches the step 101 at the end of the first game. Thus, with reference to FIG. 3, when a “Second Game Win” result has been achieved, the game will proceed directly to step 104 without requiring a positive response in the test step 102 in which the system normally checks to see if a token has been entered before activating the first line. Optionally, a player could be required to enter additional tokens to activate additional lines in the “Free” or “Bonus” second game, or more than one line could be activated automatically, without the insertion of additional tokens, as part of the prize from the first game. In the present embodiment, random numbers for the current game through the next three games are previously sampled and are used to determine whether or not a demonstration is to be made in the current game, so there is a greater number of games with demonstrations, making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, a demonstration is made on the possibility of a “Second Game Win” at the beginning of the first game, but the present invention is not limited to this. The results of the second game may be randomly selected at the first game stage, with a presentation made according to the results of the second game. In the present embodiment, a plurality of random numbers to be used in the next three games can be stored in the random number store 80 , but the present invention is not limited to this, and a plurality of random numbers to be used in more or less than the next three games can also be stored in the random number store 80 . Another alternative embodiment of a slot machine applying the present invention is described below. The appearance and basic operation of the slot machine in this alternative embodiment are similar to those of the embodiment described above, so FIGS. 1 through 6 are also applicable here and will not be described again. The method for randomly selecting the prize status and the method for determining whether or not a demonstration is to be made, which are features of the alternative embodiment, are described first. As described above, the prize status is randomly selected as result of a match between the random number values sampled at the start of the game and the groups of numerical values for awarding a prize which are stored in the prize table in the ROM 51 . FIG. 9 is a flow chart of the operations of the slot machine in the present embodiment. FIG. 10 illustrates the structure of the random number store in the present embodiment. FIG. 9 is a flowchart 500 illustrating operation of the slot machine in the additional alternative embodiment. The process begins with an all clear step 501 . Following the step 501 is a step 502 in which two types of random numbers are sampled for four games and are stored in the random number store. Following the step 502 is a game start step 504 in which the game is started. Following the step 504 is a test step 506 in which it is determined whether a token has been entered. If so, control passes to a test step 508 . Otherwise, the test step 506 is repeated until a token is entered. In the test step 508 , it is determined whether the start lever is ON. If so, control passes to a test step 510 . Otherwise, the test steps 506 , 508 are repeated until either a token is entered or the start lever 26 is ON. In the test step 510 , it is determined whether a “Second Game Win” condition occurs in the random number store. If so, control passes to a step 512 in which a demonstration flag is set. Otherwise, control passes from the step 510 to a step 514 . In the step 514 , a random number from a category A (described below) is sampled. Following the step 514 is a step 516 in which a random number from the first random number area of the random number store is extracted to determine the prize status for the current game. Following the step 516 is a step 518 in which there is a shift of the numbers in the random number store (as described below). Following the step 518 is a step 520 in which two types of random numbers are sampled for one game. Following the step 520 is a step 522 in which the two types of random numbers sampled in the step 520 are stored in the fourth random number storage area in the random number store. Following the step 522 is a test step 524 in which it is determined whether the demonstration flag is ON. If so, control passes to a step 526 in which a staggered reel start is made. Otherwise, control passes from the step 524 to a step 528 in which a normal reel start is made. Following the step 526 or the step 528 is a step 530 . In the step 530 , the demonstration flag is cleared when all reels stop. Following the step 530 is a game over step 532 . Following the game over step 532 , control returns to the game start step 504 . When, for example, the main power source switch of the slot machine is turned on, or when a clear switch not shown in the figures is switched ON, the entire system is initialized, the random numbers stored in the random number store 90 shown in FIG. 10 are cleared, and the demonstration flag described below is cleared in the step 501 . As shown in FIG. 10, the random number store 90 has four areas: a first random number area 91 , a second random number area 92 , a third random number area 93 , and a fourth random number area 94 , in each of which are provided two types of areas for first and second random numbers. The random number store 91 can thus store eight random numbers consisting of random numbers α1 and α2, random numbers β1 and β2, random numbers γ1 and γ2, and random numbers δ1 and δ2. Here, the random numbers stored in the random number store 90 are referred to as random numbers B. Either of the two types of random numbers (first and second random numbers) stored in the first random number area 91 is used in the random selection of the current game prize status, either of the two random numbers stored in the second random number area 92 is used in the random selection of the prize status in the game following the current game, either of the numbers stored in the third random number area 93 is used in the random selection of the prize status of the subsequent game, and either of the random numbers stored in the fourth random number area 94 is used in the random selection of the prize status in the game after that. That is, random numbers to be used up through the next three games from the current game are stored. In this embodiment, separate random numbers that are not stored in the random number store 90 are also provided. These random numbers are referred to as random numbers A. The random numbers A are random numbers obtained by the random generation of two types of numbers such as 0 and 1. The random number used in the current game is selected from between the two random numbers (first and second random numbers) stored in random number 1 of the random store 90 , depending on whether the random number A is 0 or 1. In the present embodiment, the prize status, that is, the position where the reels 4 L, 4 C, 4 R stop, can be determined with one random number. The present invention is not limited to this, however, and random numbers may be provided for each reel. To return to the description in FIG. 9, in the step 502 , random numbers for four games (total of eight random numbers) are sampled, the sampled random numbers are stored in the four random number areas 91 - 94 in the random number store 90 , and the slot machine is put in game start mode in the step 504 . Whether or not a token has been inserted is then detected in the step 506 , and after a token has been inserted, whether or not the start lever 5 or spin switch 8 has been pulled on is then detected in the step 508 . When the start lever 5 or spin switch 8 is on, the step 510 checks to see whether or not any of the eight random numbers in the random number store 90 correspond to a “Second Game Win” state, that is, a prize allowing a second subsidiary game to be played. When there is no “Second Game Win” random number, the game advances to the step 514 , and when there is a “Second Game Win” random number, a demonstration flag is set in the step 512 . In the step 514 , the random numbers A described above are sampled, and the random number used in the current game is determined from among the two types of random numbers (random numbers (α1 and α2) stored in the first random number area 91 of the random number store 90 based on the value of the random number A. The random number thus determined is taken from the random number store 90 and is used for the random selection of the prize status of the current game to determine the prize status of the current game in the step 516 . The two types of random numbers scored in the second random number area 92 of the random number store 90 are then moved to the first random number area 91 , the two types of random numbers stored in the third random number area 93 are moved to the second random number area 92 , and the two types of random numbers stored in the fourth random number area 94 are moved to the third random number area 93 , in the step 518 . Two new random numbers to be stored in the fourth random number area 94 of the random number store 90 are then sampled in the step 520 and stored in the fourth random number area 94 in the step 522 . Here, the system checks to see whether or not the demonstration flag is ON, namely, is set in the step 524 . When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 528 , and when the demonstration flag is ON, the reels start rotating while staggered (for example, reel 4 L is rotated, and a little while later reels 4 C and 4 R are rotated) in the step 526 . In the present embodiment, a demonstration is made a little after the reels begin to rotate. That is, the player knows there is no probability of a “Second Game Win” when the reels start to rotate simultaneously, whereas the knowledge that there is a probability of a “Second Game Win” when the reels start rotating while staggered gives the player greater hope. However, whether or not the random number for the “Second Game Win” is actually used is randomly selected after the demonstration flag has been set, so the result sometimes ends up a “loss” despite the demonstration, contradicting the expectations of the player and arousing his or her ire. Thus, when all the reels have stopped, the demonstration flag is cleared in the step 530 , a second game is played when there is a “Second Game Win,” and the game is over upon the conclusion of the second game. The system subsequently returns to the step 504 , and the next game is begun. When there is no “Second Game Win” in the step 510 , the game is over, and the system then returns to the step 504 for the next game. In the present embodiment, random numbers for the current game through the next three games are previously sampled and are used to determine whether or not a demonstration is to be made in the current game, so there is a greater number of games with demonstrations, making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, random numbers used in the current game are selected from two types of numbers (first and second random numbers), so a total of eight random numbers are used as a basis for determining whether or not a demonstration is to be made, thus increasing the number of games with demonstrations and making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, a demonstration is made on the possibility of a “Second Game Win” at the beginning of the first game, but the present invention is not limited to this. The results of the second game may be randomly selected at the first game stage, with a presentation made according to the results of the second game. In the present embodiment, a plurality of random numbers to be used in the next three games can be stored in the random number store 90 , but the present invention is not limited to this, and a plurality of random numbers to be used in the next several games can also be stored in the random number store 90 . In the present embodiment, random numbers A allowing two types of random numbers to be taken are provided, and two different types of random numbers used per game are stored in the random number store 90 , but the present invention is not limited to this; random numbers A allowing several random numbers to be taken may be provided, and the random numbers used per game may be stored in groups of several in the random number store 90 . The demonstration means in the present embodiments involved staggering the reels, but the invention is not limited to this and may also be constructed so as to appeal to the overall senses of the player by flashing the display lamps of the prize line or the sound from a sound generator. The embodiments described above were related to mechanical types of slot machines in which reels are rotated but the present invention is not limited to this mechanical type of slot machine and can also be applied to video game machines. The present invention is not limited to slot machines and can be applied to poker game machines or any other type of game machine allowing the game results to be randomly selected. When the present invention is applied to video game machines, the display image can be warped, for example, as a demonstration. As described above, the game machine described herein arouses the interest of the play to play more games because demonstrations are made when a “Second Game Win” has been obtained by random selection to determine the game prize status. In another embodiment, the game machine described herein randomly selects game results from the current game to the next several games, and determines whether or not a demonstration is to be made in the current game, so there are more games with presentations, allowing effective demonstrations to be made to arouse the interest of the player in playing more games. In an alternative embodiment, the game machine described herein selects the game result state to be used in the current game from among various types states, so there are more games with presentations, allowing effective demonstrations to be made to arouse the interest of the player in playing more games. While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be limited only by the following claims.

In a game machine, game result conditions may be randomly selected for a predetermined number of games among a plurality of given game result conditions and a demonstration may be made to provide a player of the game with a feeling of higher probability of winning a prize in the game when the randomly selected game result conditions include a given specific game result condition. The demonstration may be made by a variety of possible techniques, including using a flashing light or changing the volume or tone of a sound. Random numbers may be sampled in advance for random selection of game result conditions for the current game and for one or more games that will follow the current game, i.e., ranging several games down from the current game. These random numbers may be used to determine whether or not a demonstration should be made in the current game. As a result, more games will have demonstrations than in existing games, in which only the current games status can be considered, and more effective demonstrations may be made to enhance a player's interest in playing more games. The present invention is a game machine that randomly selects the game result conditions of a first game by lottery from among a plurality of conditions, and that determines the game results on the basis of the randomly selected results, wherein the player is alerted by a presentation to the fact that a “Second Game Win” condition exists among randomly selected conditions.

RELATED APPLICATION DATA This application is based on and claims the benefit of U.S. Provisional Patent Application No. 60/478,480 filed on Jun. 13, 2003, the disclosure of which is incorporated herein by this reference. STATEMENT OF GOVERNMENT FUNDING The United States Government provided financial assistance for this project through the National Science Foundation under Grant No. DMR 0221993 and through the Army Research Office under Grant No. DAA 19-00-0-0471. Therefore, the United States Government may own certain rights to this invention. BACKGROUND This invention relates generally to semiconductor materials and, more particularly, to a method for growing direct-gap GeSn epilayers and nanostructures directly on silicon substrates. Light-emitting semiconductor devices rely on materials that possess direct band gaps. Interestingly, none of the elemental group-IV materials are direct-gap semiconductors: diamond, silicon, and germanium have indirect band gaps, and cubic α-tin is a zero-gap semi-metal. Compounds based on these elements, such as SiC and the Si 1-x Ge x alloys, are also indirect-gap semiconductors. It has been recognized that the Si 1-x Ge x system is a nearly ideal semiconductor alloy, with a lattice constant and interband optical transition energies that are essentially linear functions of x. See O. Madelung, Semiconductors—basic data (Springer, Berlin, New York, 1996). Because these semiconductors have indirect band gaps, however, the have been precluded from use as active layers in light-emitting diodes and lasers. It has also been recognized, on theoretical grounds, that the group-IV Sn x Ge 1-x system is a possible exception to the indirect band gap behavior of group IV materials. The band gap of the Sn x Ge 1-x alloy is expected to undergo an indirect-to-direct transition, since the direct band gap has a value of 0.81 eV in Ge and becomes negative (−0.4 eV) in gray (α-) Sn. See M. L. Cohen and J. R. Chelikowsky, Electronic Structure and Optical Properties of Semiconductors (Springer, Heidelberg, Berlin, New York, 1989). A linear interpolation between Ge and α-Sn places the crossover at x=0.2, and this simple estimate agrees remarkably well with detailed electronic structure calculations within the virtual crystal approximation. See D. W. Jenkins and J. D. Dow, Phys. Rev. B 36, 7994 (1987); K. A. Mader, A. Baldereschi, and H. von Kanel, Solid State Commun. 69, 1123 (1989). This knowledge has stimulated intense experimental efforts to grow Sn x Ge 1-x compounds that are of high enough quality to be used for microelectronic and optical device applications. These efforts, however, have previously been hampered for a number of reasons. There is an enormous lattice mismatch (15%) between Ge and α-Sn, and the cubic α-Sn structure is unstable above 13° C. As a result, the system is highly metastable and cannot be produced in bulk form. Efforts have been made to grow metastable films of Sn x Ge 1-x by molecular-beam epitaxy (MBE). See G. He and H. A. Atwater, Phys. Rev. Lett. 79, 1937 (1997); O. Gurdal, R. Desjardins, J. R. A. Carlsson, N. Taylor, H. H. Radamson, J.-E. Sundgren, and J. E. Greene, J. Appl. Phys. 83, 162 (1998); M. T. Asom, E. A. Fitzgerald, A. R. Kortan, B. Spear, and L. C. Kimerling, Appl. Phys. Lett. 55, 578 (1989). A major problem encountered in the MBE approach, however, is the low thermal stability of the materials and the propensity of Sn to segregate toward the film surface. Some progress has been made, as described by H. Höchst, M. A. Engelhardt, and D. W. Niles, SPIE Procedings 1106, 165 (1989) and C. A. Hoffman, et al., Phys. Rev. B 40, 11693 (1989), but the large compositional dependence of the lattice constant limits this approach to a narrow range of compositions near the Sn-rich end. For the Ge-rich Ge 1-x Sn x alloys, which are of more interest technologically, pure Ge is an obvious choice as a substrate, and in fact fully strained Sn n Ge m superlattices as well as random Ge 1-x Sn x alloys on Ge have been demonstrated. See W. Wegscheider, K. Eberl, U. Menczigar, and G. Abstreiter, Appl. Phys. Lett. 57, 875 (1990); O. Gurdal, et al., Appl. Phys. Lett. 67, 956 (1995). Unfortunately, a major disadvantage of Ge substrates is that tetragonally distorted Ge 1-x Sn x films on Ge are not expected to display an indirect-to-direct transition. Ge-rich Sn x Ge 1-x films have been grown on Si substrates using Ge buffer layers. See P. R. Pukite, A. Harwit, and S. S. Iyer, Appl. Phys. Lett. 54, 2142 (1989); G. He and H. A. Atwater, Phys. Rev. Lett. 79, 1937 (1997). The optical properties of these MBE-grown films, however, differ very markedly from those observed in conventional semiconductor alloys: individual interband transitions are not observed, and the position of the band edges is obtained from fits that must incorporate transitions not found in pure Ge. There is a need, therefore, for a method of growing direct gap, device-quality Sn x Ge 1-x alloys directly on Si substrates without using buffer layers. It is an object of the present invention to provide such a method and semiconductor structure with a well defined Ge-like band structure. It is another object of the present invention to such a method that is practical to implement and that can be used to produce such semiconductor structures in bulk device quality form. Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, on may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by the instrumentalities and combinations pointed out herein. SUMMARY OF THE INVENTION To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, we provide a novel process for synthesizing device-quality alloys and ordered phases in a Sn—Ge system using an ultra-high vacuum (UHV) chemical vapor deposition (CVD) process. The process is based on precursor CVD, in which growth mechanisms and surface kinetics are substantially different than those inherent to MBE processes. The process can be used to generate new materials (i.e., epilayers and nanostructures) that cannot be created by conventional CVD and MBE routes. According to one aspect of the invention, we provide a method for depositing an epitaxial Ge—Sn layer on a substrate in a CVD reaction chamber. The method includes introducing into the chamber a gaseous precursor comprising SnD 4 under conditions whereby the epitaxial Ge—Sn layer is formed on the substrate. Preferably, the gaseous precursor comprises SnD 4 and high purity H 2 of about 15-20% by volume. The gaseous precursor is introduced at a temperature in a range of about 250° C. to about 350° C. Using the process of our invention, we have grown device-quality Sn—Ge materials directly on Si substrates. The Ge—Sn layer can comprise Sn x Ge 1-x , where x is in a range from about 0.02 to about 0.20. The substrate can comprise silicon, such as Si(100). We have determined the optical properties of strain-free Ge 1-x Sn x , films grown directly on Si. Unlike previous results reported by others, our films show clear evidence for a well-defined Ge-like band structure and interband transitions consistent with a group IV material, demonstrating that Ge 1-x Sn x alloys are viable candidates for a variety of novel devices based solely on group-IV materials. Thus, the method of our invention can be used to fabricate novel Ge—Sn semiconductor materials with tunable band gaps, which are suitable for microelectronic and optical devices such as highly sensitive IR photodetectors (1.55-30 μm). For example, the process of our invention can be used to make semiconductor structures comprising Ge 1-x Sn x alloys (x=0.02-0.15) that exhibit adjustable direct bandgaps between 0.7 eV and 0.4 eV, novel ordered structures with composition Ge 5 Sn 1 , strained direct gap Ge layers grown on Sn 1-x Ge x buffer layers, as well as related multilayer Si/Ge 1-x Sn x /Ge heterostructures that are easy to manufacture and are predicted to exhibit intense absorption at 1.55 μm, the communication wavelength. The optical properties of these materials indicate that they can be used to fabricate new and efficient infrared photodetectors and sensors and related optical communication devices. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate the presently preferred methods and embodiments of the invention. Together with the general description given above and the detailed description of the preferred methods and embodiments given below, they serve to explain the principles of the invention. FIG. 1 shows Rutherford backscattering (RBS) aligned (gray line) and random (black line) spectra of two representative SnGe films (A: Sn 0.02 Ge 0.98 and B: Sn 0.12 Ge 0.88 ) grown on Si according to the present invention. FIG. 2 is an electron micrograph showing the interface region of a representative SnGe film (Sn 0.02 Ge 0.98 ) grown on Si according to the invention. The arrows point to Lomer defects at the interface accommodating the lattice mismatch between Si and SnGe. FIG. 3 is a set of electron micrographs showing the entire film thickness (bottom) and the a magnified view of the surface (top) for another representative SnGe film (Sn 0.06 Ge 0.94 ) grown on Si according to the invention. Note highly uniform film thickness with relatively few defects and atomically flat surface topology. FIG. 4 is a graph of the absorption coefficients of bulk Ge and of Sn 0.02 Ge 0.98 alloy grown on Si according to the invention. The graph shows the order-of-magnitude increase of energy absorption at the 1.55 μm wavelength resulting from the addition of a small concentration of Sn. FIG. 5 is a graph of the second derivative of the dielectric function from ellipsometric measurements showing the direct band gap E 0 for Sn 0.02 Ge 0.98 and Sn 0.14 Ge 0.86 alloys grown on Si according to the invention. The direct bandgap for Sn 0.02 Ge 0.98 and Sn 0.14 Ge 0.86 are 0.74 eV and 0.41 eV respectively, compared to 0.81 eV for Ge FIG. 6 shows the numerical second derivative of the imaginary part of the dielectric function near the E 1 /E 1 +Δ 1 transitions for two Sn x Ge 1-x films. The dashed lines show theoretical fits. The E 1 for Sn 0.02 Ge 0.98 and Sn 0.14 Ge 0.86 are 2.07 eV and 1.78 eV respectively, compared to 2.12 eV for Ge. FIG. 7 is a pair of graphs showing (in the top graph) Ge band structure defining the position of important bandgaps related to critical point in the ellipsometry measurements and (in the bottom graph) real (∈ 1 ) and imaginary (∈ 2 ) parts of pseudodielectric function for Ge 1-x Sn x , x=0.16 (real part—solid line, imaginary part—dotted line) grown on Si (111). FIG. 8 shows complex dielectric function of Ge 1-x Sn x alloys at x=0.08 (dotted), x=0.14 (dashed), and x=0.20 (dot-dashed) in comparison with bulk Ge (solid) indicating a monotonic reduction in critical point energies with increasing Sn content. FIG. 9 depicts photoreflectance spectra (at 15K) of Ge 1-x Sn x showing a red shift of the direct bandgap E o for samples with 2% Sn (top trace) and 4% Sn (bottom trace) relative to that of pure Ge (vertical line) FIG. 10 is an XTEM micrograph of a Ge 5 Sn sample demonstrating that an ordered phase forms adjacent to the Si(111) interface throughout the layer. The inset image is the diffraction pattern of the entire layer and the Si substrate, which shows a clear set of superlattice spots corresponding to the ordering along the (111) direction. FIG. 11 shows experimental and simulated Z-contrast images of random and ordered Ge 5 Sn alloys according to the invention. Frames (a) and (b) show experimental and simulated images, respectively, from a double banded structure. Frames (c) and (d) show experimental and simulated images, respectively, from a single-banded structure. FIG. 12 depicts the models of the layered Ge 5 Sn alloys consistent with the Z-contrast atomic resolution microscopy. FIG. 13 shows the predicted band gaps of tensile-strained Ge as a function of the Sn concentration in the Sn x Ge 1-x buffer layer. FIG. 14 is an XTEM micrograph of the entire Si/Sn—Ge/Ge heterostructure thickness (top panel) showing virtually no defects terminating at the top surface. The magnified view of the interface (bottom panel) shows perfect heteroepitaxy between SnGe and Ge. Plan view TEM analysis indicates (not shown) that the defects are mainly concentrated at the Ge—Sn buffer layer. FIG. 15 is a sequence of LEEM frame-captured images from an 8-μm diameter area of GeSn growth showing layer-by-layer growth. The thickness of the GeSn epitaxial layer is indicated below each image. FIG. 16 is an XTEM image of a Ge 1-x Sn x (x=0.03) island on Si(100), showing a small quantum dot exhibiting highly coherent epitaxial and defect-free character. The micrograph illustrates the relationship between size and quality of epitaxial growth. FIG. 17 is an XTEM image of another Ge 1-x Sn x (x=0.03) island grown on Si(100) showing a larger island in which strain is relieved via formation of (111) stacking faults. DESCRIPTION We have developed a novel chemical vapor deposition (CVD) process that permits device-quality single-crystal Ge 1-x Sn x alloys to be grown directly on Si. Using our novel process, we have achieved systematic growth and characterization of samples of strain free Ge 1-x Sn x alloys with concentrations of about 2-20 at. % Sn prepared directly on Si(100) substrates. The observed crystal properties are superior to those of pure Ge films grown on Si, indicating that Sn incorporation in tetrahedral Ge sites, even at modest concentrations, leads to superior structural and strain behavior compared to Ge, Si—Ge, and related systems. The high Sn content materials form superlattice structures that play a critical role in stabilizing Sn at substitutional sites in the Ge lattice. The process of the present invention invariably produces films with high uniformity that possess remarkably smooth surface morphologies (typical AFM rms values are 0.5 and 1.4 nm) and extremely low densities of threading defects, particularly for Sn concentrations between 2% and 6%. These results are remarkable, because the quality of pure Ge films of Si grown by similar methods is much worse. Films grown according to our invention are also very intriguing, because Sn x Ge 1-x alloys have previously been predicted to become direct-gap semiconductors for concentrations near x=0.2. See D. W. Jenkins and Y. D. Dow, Phys. Rev. B 36, 7994 (1987); K. A. Mader, A. Baldereschi, and H. von Kanel, Solid State Commun. 69, 1123 (1989). The optical properties of the films that we grew provide evidence for a well-defined, Ge-like band structure. Individual optical transitions can be easily identified and compared with those in pure Ge, and we find a systematic narrowing of the band gaps with increasing Sn concentration. A key aspect of the process of our invention is the development of a low temperature pathway based on reactions of stabilized gaseous SnD 4 , a simple and highly practical Sn source. CVD sources that are normally used in the synthesis of Si-based semiconductors are SiH 4 and GeH 4 . However, the analogous SnH 4 molecule is unstable near room temperature due to the low Sn—H bond energy and is thus unsuitable for deposition applications. Since the substitution of deuterium for hydrogen should increase the kinetic stability of the molecules, we experimented with (Ph)SnD 3 and SnD 4 as possible sources for the growth of Sn-based semiconductors, as we described in M. Bauer, et al., Appl. Phys. Lett. 81, 2992 (2002), which is incorporated herein in its entirety by this reference. (Ph)SnD3 is a relatively stable Sn source, however, its low room temperature vapor pressure severely limits its application in growing high Sn concentration films. In the case of pure SnD 4 , the enhanced stability provided by D is insufficient at 22° C., but we discovered that the combination of perdeuterated SnD 4 with high-purity H 2 (15-20% by volume) remains remarkably stable at 22° C. for extended time periods. This formulation represents the simplest possible source, and the preferred source, of Sn atoms for the growth of novel Sn—Ge systems of our invention. According to one aspect of our invention, the growth of Sn x Ge 1-x film proceeds at remarkably low temperatures, between 250° C. and 350° C., which makes it possible to grow thick films (50-1000 nm or higher) with Sn concentrations up to 20%. Since our films grow strain free there is in principle no upper limit in thickness and concentration that can be achieved. The material is strain-free, with lattice parameters that are adjustable between 5.772 Å and 5.833 Å. The lattice mismatch between the Sn x Ge 1-x layer and the Si substrate is accommodated by the formation of periodic Lomer edge dislocations which are parallel to the interface plane and do not degrade the crystallinity and properties of the film. Method for Growing Ge 1-x Sn x Directly on Si We conducted depositions of Ge—Sn materials on Si according to the method of our invention in a UHV-chemical vapor deposition reactor by reacting appropriate concentrations of Ge 2 H 6 and SnD 4 on Si substrates at the remarkably low substrate temperatures between 250 and 350° C. and at 10 −1 -10 −3 Torr. For a typical synthesis, single-crystal Si (111) and Si (100) substrates are prepared for growth by a known modified RCA process, followed by hydrogen passivation of their surface. The modified RCA process is explained more fully in V. Atluri, N. Herbots, D. Dagel, H. Jacobsson, M. Johnson, R Carpio, and B. Fowler, Mater. Res. Soc. Symp. Proc. 477, 281 (1997), which is incorporated herein in its entirety by this reference. We used perdeuterated SnD 4 combined with high-purity H 2 (up to 15%-20% by volume) as the source of Sn. The reaction of Ge 2 H 6 and SnD 4 on the Si substrates produced epitaxial Ge 1-x Sn x films. The following examples help to further explain how we grew Ge 1-x Sn x films on Si using the method described above and demonstrate the high quality of the resulting films. It will be understood, however, that the examples are illustrative of the process and materials of the invention that the invention is not limited only to these examples. EXAMPLE Ge 1-x Sn x (x=2-17%) on Si(100) Using the method described above, we grew samples of epitaxial Ge 1-x Sn x films on Si(100) substrates at various temperatures between 250 and 350° C. Rutherford backscattering (RBS) revealed that thick layers (50-500 nm) with Sn contents of 13 to 17 at. % were deposited reproducibly between 300 and 280° C., respectively. Depositions at higher temperatures between 310 and 350° C. gave Sn contents of 12 to 2 at. %, respectively, indicating an inverse dependence of the growth temperature on Sn incorporation. To determine the quality of epitaxial growth and evaluate the Sn substitutionality, RBS random and aligned spectra were recorded for the sample films. FIG. 1 shows typical (RBS) spectra for samples containing 2% and 12% Sn, demonstrating high quality Ge—Sn growth on Si(100). As shown in FIG. 1 , both Sn and Ge channel remarkably well despite the large difference in lattice constant with the Si substrate. The channeling of Sn provides proof that this element must occupy substitutional tetrahedral sites. The extent of substitutionality can be assessed by comparing the values of x min between Ge and Sn in the same sample (x min is the ratio of the aligned versus random peak height). The value of x min is 4%, for both Ge and Sn in the Ge 0.98 Sn 0.02 sample and 35% in the Ge 0.88 Sn 0.12 sample, indicating that the entire Sn content is substitutional. The 4% value approaches the practical limit of about 3% for structurally perfect Si, which is unusual for a binary crystal grown directly on Si. The 35% value is relatively high and is likely due to some mosaic spread in the higher Sn-content crystal due to the increase in lattice mismatch. We are the first group to publish clear evidence for nearly perfect RBS channeling by the Sn and the Ge. This is a crucial experiment because it demonstrates the perfect Sn substitutionality in our samples Low-energy secondary ion mass spectrometry showed background levels of D, H, and C and revealed highly uniform Sn and Ge elemental profiles throughout the film. Homogeneity at the nanometer scale was confirmed using energy dispersive x-ray nanoanalysis in a high-resolution electron microscope with probe size less than 1 nm. Compositional profiles showed homogeneous Ge and Sn distribution with no evidence of phase separation or Sn precipitation. We investigated the structural properties of sample films using cross-sectional electron microscopy (XTEM) and high-resolution x-ray diffraction. The XTEM studies revealed thick single-crystal layers with remarkably low concentrations of threading defects. FIG. 2 is a high-resolution cross-sectional electron micrograph of the interface region of a representative Ge 0.98 Sn 0.02 grown on Si(100), which shows virtually perfect epitaxial growth, with arrows showing the location of misfit dislocations. FIG. 3 is a set of cross-sectional electron micrographs demonstrating high quality heteroepitaxial growth of a representative Ge 0.94 Sn 0.06 grown on Si(100). The top panel of FIG. 3 shows atomically flat film surface morphology. The middle panel of FIG. 3 shows the exceptional uniformity of the film thickness. The bottom panel of FIG. 3 is a high-resolution electron micrograph of the interface region showing virtually perfect epitaxial growth, with arrows showing the location of misfit dislocations. The inset image of the bottom panel shows a selected-area diffraction pattern of the Ge 0.94 Sn 0.06 film. Typical images in the (110) projection show occasional threading dislocations and {111} stacking faults sometimes extending through to the uppermost surface. The estimated density of these defects is less than ˜10 7 /cm 2 , a value well within the levels considered acceptable for device application. The predominant defects accommodating the large misfit are Lomer edge dislocations at the interface, which are parallel to the interface plane and should not degrade electrical properties and device performance. Finally, the film surface is virtually flat at the atomic level. The typical rms roughness of 0.5 to 1.4 nm, as observed by atomic force microscopy, is comparable to atomic step heights on Si surfaces. X-ray measurements in the θ-2θ mode show a strong peak corresponding to the (004) reflection. In-plane rocking scans of the (004) reflection have a full width at half maximum between 0.25 and 0.50 degrees, indicating a tightly aligned spread of the crystal mosaics. The unit cell parameters obtained from the (004) reflection for samples containing 2, 3, 4, 9, 11, and 15 at. % Sn (as measured by RBS) were 5.6720, 5.6936, 5.7111, 5.7396, 5.7611, and 5.802 Å, respectively. These values are intermediate to those of Ge (5.658 Å) and α-Sn (6.493 Å), and they increase monotonically with increasing Sn concentration. Virtually identical values were obtained from the selected area electron diffraction patterns. Digital diffractogram analysis of TEM micrographs confirmed the measured values of the unit cell constants and also showed that the lattice parameter did not vary locally throughout the sample. High resolution off axis measurements and reciprocal space maps of the (004) and (224) reflections show that are materials are completely relaxed and free of local structural strains. The Sn concentration as measured by RBS, the corresponding cell parameter estimated from Vegard's law, α(Vegard), and the experimental unit cell parameters α are listed in Table 1 set forth below. Also included are the results of theoretical calculations, based on ab initio density functional theory, for the lattice constants as a function of Sn. There is close agreement between theory and experiment. A striking feature is that a positive deviation from Vegard's law is found for both the experimental and theoretical values, which is in direct contrast with the compositional variation of the lattice constant in the classic Si 1-x Ge x and Si 1-x C x group IV alloys. In those systems the deviations from Vegard's law are usually negative, as described in Z. Charafi and N. Bouarissa, Phys. Lett. A 234, 493 (1997) and H. Kajiyamna, S-I. Muramatsu, T. Shimada, and Y. Nishino, Phys. Rev. B 45, 14005 (1992), which are incorporated herein by this reference. TABLE 1 Observed and calculated lattice parameters. The observed lattice parameter composition dependence in the range 0%-15% Sn content is compared with Vegard's law. The calculated values are obtained from a first- principles local density approximation static lattice calculation. The “relaxed” results correspond to fully optimized structures. Observed Calculated % Sn a(Vegard) a(observed) Sn/Ge a(Vegard) a(relaxed) 0 5.658 5.658 0 5.626 5.626 2 5.675 5.672 1/64 5.639 5.639 3 5.683 5.694 2/64 5.652 5.653 4 5.691 5.711 4/64 5.678 5.683 9 5.733 5.740 8/64 5.729 5.737 11 5.750 5.761 12/64  5.781 5.792 15 5.783 5.802 1 6.456 6.456 In order to further characterize the local bonding environment in the Ge—Sn lattice, the Raman spectrum of each sample was acquired. The materials showed a strong peak corresponding to Ge—Ge phonon mode, which is downshifted substantially with respect to pure Ge. The vibrational frequencies decrease monotonically with increasing Sn concentration due to the combined effects of mass substitution and elongation of the average Ge—Ge bond distances. The compositional dependence of the Ge—Ge frequency shift can be fitted with an expression of the form Δω(x)=−72x (in cm −1 ) where x is the Sn concentration. This dependence agrees well with an extrapolation of similar results for strainfree Si 1-x Ge x and Si 1-x C x alloys based on a simple model for the compositional dependence of Raman modes in alloy semiconductors, described by J. Menendez, in Raman Scattering in Materials Science , edited by W. H. Weber and R. Merlin (Springer, Berlin, 2000), pp. 55-103. The Ge—Sn samples were annealed between 400 and 750° C. to determine their thermal stability. The x-ray lattice parameter and the x min values of the RBS signals were measured and compared with the pre-annealed values, and XTEM and nanoprobe energy dispersive x-ray analysis were used to determine phase separation and any elemental inhomogeneity. Samples with composition Ge 0.98 Sn 0.02 were remarkably stable up to at least 750° C. and showed an improvement in crystallinity with increasing temperature. The Ge 0.95 Sn 0.05 composition remained robust up to 600° C., but displayed substantial Sn precipitation between 600-700° C. In the case of the Ge 0.88 Sn 0.12 and Ge 0.85 Sn 0.15 compositions, the corresponding thermal stability range was reduced to below ˜500 and ˜450° C., respectively. Example Growth of Ge 1-x Sn x (x=17-20%) on Si(100) and Si(111) Using the process of our invention, we conducted further materials synthesis by reacting appropriate concentrations of Ge 2 H 6 and SnD 4 on single crystal Si(111) and Si(100) substrates at a temperature of ˜250° C.-280° C. The aim was to increase the Sn content beyond 15 at. % and to explore growth on Si(111) substrates. For a typical synthesis, the substrates were prepared for growth by the modified RCA process described above, followed by hydrogen passivation of their surface. The reactions of Ge 2 H 6 and SnD 4 on the pure Si template produced thick films (70-200 nm) with Sn concentrations of 17-20 at. %, as measured by Rutherford backscattering (RBS). The RBS random and aligned spectra were also recorded and compared. The ratio between the aligned and random peak heights, which measures the degree of channeling of the He 2+ ions, was identical for both Ge and Sn, indicating unequivocally that that the entire Sn content occupies substitutional sites in the average diamond cubic structure. High-resolution X-ray diffraction indicated single-phase crystalline films in epitaxial alignment with the Si substrate, with no evidence of significant tetragonal distortion. The unit cell parameters obtained from the diffraction data for samples with 18 and 20 at. % Sn were 5.82 Å and 5.84 Å respectively. For the Si (111) sample, in-plane rocking scans of the (004) reflection have a full-width-at-half-maximum of 0.07° C. indicating highly aligned crystal mosaics. Low-energy secondary ion mass spectrometry confirmed highly uniform Sn and Ge elemental profiles throughout the film and revealed the absence of D and H impurities. Optical Properties of Sn x Ge 1-x Films We studied the optical properties of sample Sn x Ge 1-x films grown on Si substrates according to our invention with spectroscopic ellipsometry, which yields the complex pseudo-dielectric function (δ 1 +ε 2 ) and the film thickness. Ellipsometric measurements are particularly challenging in Sn x Ge 1-x alloys due to the expected existence of optical transitions from the mid-infrared to the ultraviolet. We used a combination of two instruments. A VASE® variable angle spectroscopic ellipsometer (available from J.A. Woollam and Co. of Lincoln, Nebr.) covered the 0.5 eV-4.1 eV range. This instrument is equipped with a Xenon lamp, a double monochromator, and am extended infrared InGaAs detector. An IR-VASE® ellipsometer (also available from J.A. Woollam and Co.) was used to cover the 0.03 eV-0.83 eV range. This ellipsometer is based on a Fourier-transform spectrometer. The optical constants for our films were obtained by modeling our samples as three-layer systems comprising a surface layer, the Sn x Ge 1-x film, and the Si substrate. Numerical derivatives of the dielectric function were computed and compared with analytical models of the dielectric function near critical points in the electronic density of states. FIG. 4 is a graph of the absorption coefficients of bulk Ge and of a Sn 0.02 Ge 0.98 alloy grown on Si according to our invention. The absorption coefficients of the Sn 0.02 Ge 0.98 alloy were obtained from the ellipsometry data. As shown in FIG. 4 , the addition of a very small Sn concentration increases by an order of magnitude the absorption coefficient at the 1.55 μm wavelength. Because this wavelength is typically used for fiber optic communications, this demonstrates the potential of Sn x Ge 1-x alloy for use in high-efficiency infrared detectors. By computing derivatives of the optical constants as a function of the photon energy, we determined the energies of critical points in the electronic band structure as well as the direct band gap E 0 , FIG. 5 shows the second derivative of the imaginary part of the dielectric function for two samples of Sn x Ge 1-x films (where x=0.02 and 0.14) grown according to the invention. The sharp feature shown in FIG. 5 is associated with the direct band gap E 0 , which can be determined with a precision of 10 meV. As shown in FIG. 5 , the direct bandgap for Sn 0.02 Ge 0.98 is E 0 =0.74 eV and the direct bandgap for Sn 0.14 Ge 0.86 is E 0 =0.41 eV. Comparing this with E 0 =0.81 eV for Ge, we find a dramatic band gap reduction of 50% for only 14% Sn. FIG. 6 shows the second derivative of the imaginary part of the dielectric function near the E 1 transition for Sn 0.02 Ge 0.98 and Sn 0.14 Ge 0.86 alloys grown on Si according to the invention. As shown in FIG. 6 , E 1 for Sn 0.02 Ge 0.98 and Sn 0.14 Ge 0.86 are 2.07 eV and 1.78 eV, respectively. FIG. 6 shows ellipsometric results near the E 1 and E 1 +Δ 1 transitions between the highest valence bands and the lowest conduction band at the L-point of the fcc Brillouin zone. The shape of the curve is very similar to that obtained for pure We, confirming the high quality of our films. From these data one can also determine the relevant optical transitions with high accuracy. We also performed Raman resonance scattering experiments to show qualitatively the reduction in band gap with increasing Sn content in selected samples. The Raman cross-section in pure Ge undergoes a resonant enhancement for laser photon energies near the E 1 and E 1 +Δ 1 gaps, as described by F. Cerdeira, W. Dreyrodt, and M. Cardona, Solid State Commun. 10, 591 (1972). We performed similar measurements for a Ge 0.95 Sn 0.05 alloy and a Ge reference. The net result was a redshift of E 1 and E 1 +Δ 1 by about 100 meV relative to pure Ge. We performed IR transmission measurements for several Ge—Sn samples in the range of 2000 and 10,500 cm −1 . While the exact location of the absorption edges was not determined, our results clearly demostrate that between 4000 and 8000 cm −1 the absorption coefficient increases monotonically by a substantial amount with increasing Sn content. The most plausible explanation is a decrease of the band gap as a function of composition, since such a reduction is likely to result in increased absorption at a fixed photon energy above the bandgap. We also used UV spectroscopic, ellipsometry in the 1 to 6 eV photon energy range to investigate the band structure of Ge x Sn 1-x , with x=0-0.2. Again, for x=0, a bulk Ge crystal was used as the reference point. Referring to FIG. 7 , the top graph shows a Ge-like band structure defining the position of important bandgaps related to the critical point measurements by ellipsometry. The bottom graph of FIG. 7 shows real (∈ 1 ) and imaginary (∈ 2 ) parts of pseudodielectric function for Ge 1-x Sn x , x=0.16 (real part—solid line, imaginary part—dotted line) grown on Si (111) showing the strong qualitative similarity with the corresponding behavior of pure Ge (real part—dashed line, imaginary part—fine dashed line). Three structures at 2.1 eV, 2.9 eV, and 4.2 eV correspond to the E 1 /E 1 +Δ 1 , E 0 ′, and E 2 critical points. The features seen below 1.9 eV are interference fringes. Referring to FIG. 7 (bottom), a close examination of the imaginary part (∈ 2 of the pseudodielectric function for the Ge 0.84 Sn 0.16 sample shows a peak between 2.00 and 2.20 eV corresponding to the E 1 and E 1 +Δ 1 transitions. For the higher concentration samples (x>0.16), the E 1 and E 1 +Δ 1 transition peaks broaden significantly, resulting in only one distinguishable peak for the two transitions. A shoulder at 2.90 eV is assigned to the E 0 ′ critical point and a feature near 4.20 eV corresponds to the E 2 energy gap. We are able to obtain an accurate determination of these critical points using a derivative analysis showing their corresponding band gaps in Table 2. The critical point data indicate a systematic narrowing of the band gaps with increasing Sn concentration as shown by (also shown in FIG. 8 ) TABLE 2 Critical point energy values for Ge 1−x Sn x . For x = 0.02 and 0.20, the samples were grown on Si (111). x E 1 (eV) E 1 + Δ 1 (eV) E 0 ′ (eV) E 2 (eV) 0.00 2.11 2.31 3.12 4.36 0.02 2.03 2.24 3.06 4.32 0.08 1.99 2.16 3.07 4.27 0.16 2.09 2.94 4.16 0.18 2.01 3.01 4.17 0.20 1.99 2.95 4.12 Our results for the E 0 as well as the E 1 and E 1 +Δ 1 transitions show very large deviations from a simple linear interpolation of transition energies between Ge and α-Sn. Thus the determination of the compositional dependence of the band structure on Sn concentration is important for the design of devices based on Sn x Ge 1-x . We obtained additional data by photoreflectance for selected samples incorporating 2 and 4% Sn. We were able to obtain accurate values for the direct band gap E 0 which showed a definite decrease of the band gap energy with increasing Sn concentration. FIG. 9 compares the photoreflectance spectra of the Sn 0.02 Ge 0.98 and Sn 0.02 Ge 0.96 samples with that of pure Ge. The data were obtained at 15 K and are consistent with those obtained with IR ellipsometry. Collectively, the data in FIGS. 4-9 indicate that Sn incorporation into Ge lattice sites decreases the bandgap and critical point energies and dramatically increases the sensitivity of this system to infrared radiation. Thus, the new alloys according to our invention are excellent candidates for a new generation of IR photodetectors, with the important additional benefit that they can be grown on inexpensive Si substrates. Since films grown according to our invention grow essentially strain-free, there is in principle no upper limit to the Sn concentration that can be achieved. Thus, our approach represents the most straightforward route to direct-gap Sn x Ge 1-x alloys and a practical solution to the long-standing problem of growing direct-gap semiconductors on Si. The very large lattice mismatch between films grown according to our invention and the Si substrate opens up intriguing new opportunities for band gap and strain engineering on silicon. Ordered Phases with Composition Ge 4-5 Sn We explored the microstructural properties of Sn x Ge 1-x films of our invention by transmission electron microscopy (TEM) and conducted investigations of structure vs. composition to search for novel ordered phases that are likely to have unique and exciting properties, such as high electron mobilities and direct band gaps. We have discovered that the compositional range of about Sn 0.16-0.20 Ge 0.83-0.80 displays an unusual ordering of the atoms in the structure. We grew samples of thin epitaxial films of Sn 0.16-0.20 Ge 0.83-0.80 materials on Si(100) and Si(111) substrates using the method described above. We characterized these samples by RBS, x-diffraction and high-resolution electron microscopy, including extensive Z-contrast and electron energy loss spectroscopy (EELS) analyses at 1.7 Å resolution. The structural investigations indicate the existence of a superstructure that has a periodicity along the <111> direction that is three times larger than that of the underlying substrate. As discussed more fully below, experimental and theoretical data suggest novel phases in which the Ge and Sn atoms are aligned in the sequences of Ge—Ge—Sn 0.50 Ge 0.50 and Ge—Sn 0.25 Ge 0.75 —Sn 0.25 Ge 0.75 along the diamond <111> direction. The theoretical studies provide structural models that are consistent with the composition as well as the spectroscopic, microscopic and diffraction data of this material. We conducted energy dispersive X-ray spectroscopy on a Philips CM200 TEM with a nanometer sized electron probe, which showed that the constituent elements Sn and Ge appeared together at every nanometer scale region probed without any segregation of the individual elements. FIG. 10 is a high-resolution phase contrast image of a Ge 5 Sn 1 sample demonstrating that the ordered alloy forms directly adjacent to the Si(111) interface. Diffraction pattern (inset) of the entire layer and the Si substrate shows a clear set of superlattice spots corresponding to the ordering along the (111) direction. High-resolution phase contrast imaging of the high Sn content materials show that much of the film was dominated by a superlattice structure. Within these regions, the periodicity was tripled along the (111) direction of the underlying Si lattice. The presence of the superlattice was confirmed by single crystal selected area electron diffraction (see FIG. 10 inset). Electron diffraction analysis of the phase contrast images for the 20 at. % Sn sample deposited on (111) Si gave a lattice constant of the parent diamond structure of 5.839 Å, which is close to the value determined by X-ray diffraction (5.837 Å). The lattice parameter of the disordered phase, determined by digital diffractogram analysis of the high-resolution images, is virtually identical to that of the ordered structure indicating that the Sn concentration is uniform throughout the ordered and disordered areas of the film. Both the ordered and disordered layers showed complete heteroepitaxy with the underlying Si substrate. The fraction of the ordered phase increased with increasing Sn content, reaching approximately 60% for the 20 at. % Sn sample deposited on Si (111). The co-existence of the random and ordered alloys will cause a splitting of the critical points in the optical data, which contributes to the observed peak broadening of FIG. 7 . High-resolution Z-contrast imaging performed on a JEOL 2010F revealed the presence of two distinct atomic arrangements in the ordered alloy. Frames (a) and (c) of FIG. 11 show experimental Z-contrast images of random and ordered SnGe alloys according to the invention, with the frame width being 5 nm. Z-contrast imaging is explained in more detail by M. M. McGibbon, N. D. Browning, M. F. Chisholm, A. J. McGibbon, S. J. Pennycook, V. Ravikumar, V. P. Dravid, Science 266, 102 (1994), which is incorporated herein by this reference. In Z-contrast images, for thin samples, the intensity depends directly on the average atomic number Z of the atomic column under observation. Thus, atomic columns containing Sn appear considerably brighter than columns of pure Ge. Frame (a) of FIG. 11 is the most commonly found superstructure showing a double banded contrast consisting of periodic sequences of two Sn-rich layers with bright contrast followed by a single Ge-rich layer of dark contrast along the <111> direction. Frame (c) of FIG. 11 is a less common single banded form showing two Ge-rich layers for every Sn-rich bright layer. For a general discussion of ordering in semiconductors, see P. Mock, T. Topuria, N. D. Browning, G. R. Booker, N. J. Mason, R. J. Nicholas, M. Dobrowolska, S. Lee, and J. K. Furdyna, Appl. Phys. Lett. 79, 946 (2001) and by A. Zunger and S. Mahajan, in Handbook on Semiconductors , edited by S. Mahajan (North Holland, Amsterdam, 1994), Vol. 3, Chap. 9, p. 1399, which are incorporated herein by this reference. In our case, the ordering described above was predominantly observed in samples with an average Sn concentration close to 16-20 at. %. Thus, we constructed models of superstructures with composition Ge 5 Sn 1 . The structural models are shown in FIG. 12 . They have orthorhombic unit cells derived from the zincblende lattice and contain three distinct layers (labeled L 1 , L 2 and L 3 )) each of which contains four possible lattice sites. The long axis of the orthorhombic cells is topotactic with the [111] direction in the original diamond lattice. The top two models, denoted by “0-0-50”, represent the extreme Sn-rich scenario in which half of the sites within the L 1 layer are occupied by Sn. The bottom two “0-25-25” models of FIG. 12 have their Sn concentration distributed between both the L 1 and L 2 layers. A 50% occupancy of Sn atoms within the L 1 layer yields the “0-0-50” model which is characterized by a single Sn-rich layer alternating between two Sn-depleted layers. There are two unique ways of distributing the Sn atoms in the L 1 layer giving two models labeled 0-0-50a and 0-0-50b. Distributing the Sn atoms on 25% of the sites within the L 1 and L 2 layers, with Ge exclusively occupying the L 3 layer yields the “0-25-25” model. Similarly there are two unique ways of distributing the Sn atoms among the L 1 and L 2 layers. All models except 0-0-50b incorporate exclusively heteropolar Ge—Sn bonds and avoid higher energy first neighbor tin-tin interactions. We also constructed a series of random alloy (RA) structures by doubling the supercell along the orthorhombic b-axis to yield a 24-atom cell, and then randomly distributing four Sn atoms among the available sites. These model structures were studied using first principles quantum mechanical calculations based on density functional theory (DFT) and the local density approximation (LDA) for exchange and correlation, (explained in more detail by D. M. Ceperley, B. J. Alder, Phys. Rev. Lett. 45, 566 (1980)) as implemented in the VASP program described by T G. Kresse and J. Hafner, Phys. Rev. B 47, R558 (1993); G. Kresse and J. Hafner, Phys. Rev. B 49, 14251 (1994); and G. Kresse, J. Furthmuller, Comput. Mater. Sci. 6, 15 (1996); G. Kresse, J. Furthmuller, Phys. Rev. B 54, 11169 (1996). The shape and volume of the supercells were optimized while fully relaxing all internal atomic coordinates to an accuracy of 0.001 eV/Å. All results were obtained using the ultrasoft norm-conserving Ge and Sn pseudopotentials supplied with the VASP package. Converged results were obtained using a plane-wave basis set cutoff of 600 eV for all calculations. A 3×6×3 Monkhorst-Pack grid was used to generate 27 irreducible k-point in the orthorhombic 12-atom setting, while the same procedure generated 10 irreducible k-point for the expanded cells used for the random alloy simulations. For the random alloy, we carried out calculations on 5 of the random Sn configurations and averaged the unit cell parameters, which exhibited length and angle variances of ˜0.02 Å and 0.05 degrees, respectively. The ground state structures and energies of the five alloy structures are listed and compared in Table 3. While the 0-25-25b model is predicted to possess the lowest energy, random alloys are found to be only slightly less energetically favorable. This is consistent with the experimental finding that the majority of the material is ordered in the 20 at. % Sn sample grown on the Si (111) surface. Using the predicted structures obtained from the modeling, we simulated the Z-contrast images for the two order phases using the multi-slice codes developed by E. J. Kirkland, Advanced Computing in Electron Microscopy , Plenum Press, New York, (1998). The simulated images are shown in frames (b) and (d) of FIG. 11 and suggest that our models are in good agreement with the experimental measurements. TABLE 3 Ground state structural parameters of the orthorhombic cell and energies for the superstructures (“0-0-50”, “0-25-25”) and the random alloy (“RA”) models of Ge 5 Sn 1 . Lengths are given in Å, energies in eV and relative energies in meV/atom. a b c α β γ E (eV) ΔE/atom (meV) “0-0-50”b 7.091 4.057 10.025 90.0 90.1 90.0 −60.39283 21.8 “0-0-50”a 7.081 4.067 10.030 90.0 90.1 90.0 −60.55231 8.5 “RA” 7.059 4.089 9.957 90.0 89.8 90.0 −60.63324 1.8 “0-25-25”a 7.093 4.064 9.996 90.0 90.2 90.0 −60.64655 0.7 “0-25-25”b 7.090 4.065 9.993 90.0 90.1 90.0 −60.65462 0 Strained Ge Grown on Sn x Ge 1-x Buffer Layers According to another aspect of our invention, we also have grown nearly defect-free Ge films on Sn x Ge 1-x buffer layers grown on Si substrates according to the process described above. FIG. 13 shows a calculation of the direct and indirect edges of Ge strained to lattice-match a Sn x Ge 1-x buffer layer as a function of the Sn concentration in the Sn x Ge 1-x buffer layer. The calculation is based on deformation potential theory, and it shows a very interesting feature: strained Ge becomes a direct gap material if the Sn concentration in the buffer layer exceeds 11%. Soref and Friedman theorized this almost 10 years ago and proposed several heterostructures for p-i-n injection lasers. See R. A. Soref and L. Friedman, Superlattices and Microstructures 14, 189 (1993). Yet, until now there has not been a commercial viable method to produce such materials or to confirm the theory. A complete characterization of the strain properties of the Ge films that we grew indicates that the Ge films are tensile strained as expected for a material grown on a surface that possesses a larger lattice dimension. In a typical experiment, a Sn x Ge 1-x buffer layer having a thickness of about 20-200 nm is grown by reaction of the appropriate combinations of SnD 4 and Ge 2 H 6 according to the process described above. The Ge overlayers are then deposited at 400-450° C. by thermally activated dehydrogenation of Ge 2 H 6 on the Ge—Sn buffer layers. Cross-sectional electron micrographs of the resulting system show completely epitaxial Ge grown on Ge 0.97 Sn 0.03 FIG. 14 is an XTEM micrograph of the entire Si/Sn—Ge/Ge heterostructure thickness. As can be seen, the Ge layer is free of stacking and threading defects. Virtually all of the defects are concentrated at the Ge—Sn buffer layer, and the Ge overlayer in the upper portion of the heterostructure remains virtually defect-free. GeSn Nanostructures Grown on Silicon The successful synthesis of Sn—Ge epitaxial films on Si described above prompted us to undertake the growth of related nanostructures such as alloy quantum dots and three-dimensional islands to further explore tailoring the optical properties of this novel system. Ge—Sn nanostructures with direct tunable bandgaps combined with the underlying Si substrate (which is indispensable for viable device development) should have tremendous potential for use in infrared laser technologies. In accordance with another aspect of the invention, therefore, we have developed a new family of semiconductor quantum dots (QDs) with tunable direct bandgaps in the infrared spectral region for Si-based bandgap and lattice engineering applications. We have created closely related nanoscale architectures with unusual morphologies and nearly perfect crystallinities via new methods combing specially designed molecular sources and novel deposition techniques involving in situ observation and control of the growth process by LEEM and UHV-SEM-MBE. A survey of preliminary experiments of quantum dot growth was conducted in a molecular beam epitaxy chamber equipped with a low energy electron microscope (LEEM), allowing the entire growth process to be observed and controlled in situ and in real time. The precursor gases (Ge 2 H 6 and SnD 4 ) were adjusted in the reaction mixture so as to incorporate Sn concentration of about 2-3 at. % in the alloy. FIG. 15 shows a sequence of LEEM images from an 8-μm diameter area of GeSn growth at 350° C. The terraces, which are separated by single-height atomic steps, alternate from dark to bright contrast due to the rotation of the dimer reconstruction on the terraces, as shown in the first image in FIG. 15 . As the GeSn film was deposited on the Si(100) substrate, the contrast of each terrace changed from dark to bright or from bright to dark respectively. The contrast alternation indicates that the growth mode is layer-by-layer. The LEEM results reveal that at least for the first six monolayers, the Ge 1-x Sn x deposition takes place by the layer-by-layer growth mode. However, the contrast faded away permanently as the coverage exceeded 6 ML, indicating transition to a three-dimensional island-like growth mechanism. Continued deposition generated the desired assemblies of Ge 1-x Sn x quantum dots. The average Ge and Sn concentration was determined by RBS to be Ge 0.97 Sn 0.03 . Atomic force microscopy (AFM) indicated the presence of three-dimensional faceted islands dispersed on the surface of the substrate. XTEM revealed that the material consisted of a continuous and completely epitaxial wetting layer, followed by an array of nanoscale bump-shaped islands randomly distributed on the surface of the underlying layer. The presence of the wetting layer is consistent with the LEEM observations of two-dimensional layer-by-layer growth for the first six monolayers. FIG. 16 is an XTEM image of a Ge 1-x Sn x (x=0.03) island on Si(100), showing a small quantum dot exhibiting highly coherent epitaxial and defect-free character. The micrograph illustrates the relationship between size and quality of epitaxial growth. FIG. 17 is an XTEM image of another Ge 1-x Sn x (x=0.03) island on Si(100), showing a larger island in which strain is relieved via formation of (111) stacking faults. The smaller island shown in FIG. 16 is highly strained and completely coherent and defect free despite the large mismatch of the Ge—Sn material with the substrate. The larger island of FIG. 17 shows defects such as misfit dislocations and {111} stacking faults indicating that this material has exceeded a critical thickness beyond which the enormous strain is relieved by development of defects originating at the film/substrate interface. The combination of nanostructures and the technologically relevant Ge—Sn system is unique. CONCLUSION The above-described invention possesses numerous advantages as described herein. We have used low-temperature chemical vapor deposition to grow device quality single-crystal Sn x Ge 1-x alloys with x=0.02-0.2 directly on Si substrates. The Sn is at substitutional sites in the underlying Ge lattice and in the high Sn content materials the systems are stabilized with the formation of orthorhombic superstructures. Optical measurements show a systematic narrowing of band gaps with increasing Sn concentration proving that band gap engineering has been achieved. Thus this new system should be an excellent candidate for a new generation of R photodetectors, with the critical additional benefit that they can be easily integrated into silicon-based technology. The invention in its broader aspects it not limited to the specific details, representative devices, and illustrative examples shown and described. Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. It is therefore intended that the appended claims cover all such equivalent variations as fall within the true spirit and scope of the invention.

A method for depositing an epitaxial Ge—Sn layer on a substrate in a CVD reaction chamber includes introducing into the chamber a gaseous precursor comprising SnD4 under conditions whereby the epitaxial Ge—Sn layer is formed on the substrate. the gaseous precursor comprises SnD4 and high purity H2 of about 15-20% by volume. The gaseous precursor is introduced at a temperature in a range of about 250° C. to about 350° C. Using the process device-quality Sn—Ge materials with tunable bandgaps can be grown directly on Si substrates.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for converting β-keto esters to ketones, and to novel ketones produced therefrom. Specifically, this invention relates to the method of decarbalkoxylating alkylated β-keto esters using a phase-transfer agent to yield ketones. The present invention also relates to novel methylene-linked pyrethroid insecticides produced by the method of the invention. 2. Description of the Prior Art Ketones are very valuable commercial compounds. One synthetic route for the preparation of ketones is via the conversion of alkylated β-keto esters. Classical synthetic approaches to such conversions are known. For example, it is known that acid-catalyzed decarboxylation in an aqueous or nonaqueous medium, following alkaline hydrolysis of β-keto esters provides simple access to ketones. However, because this conversion method can be unpredictable, with little or no yield, its use as a commercial synthetic process is not desirable. Several previous and more recent approaches to ketone synthesis through conversion of β-keto esters employ a retro Claisen-type reaction. Such syntheses require a nonaqueous medium and/or high reaction temperatures, thereby presenting a potential environmental hazard and necessitating much time and expense. Also, the retro Claisen-type reactions are undesirable since they may require another method to complete the synthesis. For example, when a crown ester is used to convert several β-sp 2 carbon ester compounds to carboxylates in an alkaline medium, acidification and/or thermolysis are required to complete ketone synthesis. Consequently, there exists a need for a method of converting alkylated β-keto esters to ketones which is more predictable, cost effective, and environmentally safer than prior art processes. In addition, there is a need for a facile approach to the conversion of β-keto esters to ketones which produces a yield which is practical for commercial application. SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved process for the decarbalkoxylation of alkylated β-keto esters to produce high yields of ketones. Another object of the present invention is to provide a novel process for the conversion of the β-keto esters to ketones in a facile, economical and commercially acceptable manner. Still another object of the present invention is to provide novel methylene-linked pyrethroid insecticidal compounds. In accordance with the method of the invention, decarbalkoxylation of β-keto esters is accomplished by heating the ester in the presence of dilute aqueous alkali and an effective amount of a phase-transfer agent for a period of time sufficient to decarbalkoxylate the ester. An advantageous feature of the invention method is that the process is not specific, but may be used to prepare a limitless quantity of keto products. Examples of novel methylene-linked pyrethroid insecticides produced by the method of the invention include compounds represented by the general formula ##STR1## wherein R is 2,2-dimethyl-3-(2-methylpropenyl)cyclopropyl; 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 1-(4-chlorophenyl)-2-methyl propyl. Other novel methylene-linked pyrethroid insecticides produced by the invention method include compounds represented by the general formula ##STR2## wherein R is 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropyl. DETAILED DESCRIPTION OF THE INVENTION For purposes of this invention, the term "phase-transfer agent" is defined herein to mean a reagent that allows the transport of a reactive species between two immiscible phrases. In the preferred embodiment, the method comprises (1) forming an emulsion of a β-keto ester with dilute aqueous alkali, i.e. potassium hydroxide or sodium hydroxide, which contains an effective amount, preferably from about 0.1 to 10%, of a phase-transfer agent such as hexadecycltrimethylammonium bromide, cetyltrimethylammonium bromide, benzylcetyldimethylammonium chloride, or the like; (2) heating said emulsion at about 60° C. to 90° C., perferably under nitrogen, with stirring and sonication for about a period of time sufficient to decarbalkoxylate the ester, preferably from about 30 to 90 minutes; (3) neutralizing the reaction mixture with dilute acid, i.e. dilute sulfuric or hydrochloric acid; and (4) thereafter, recovering the resulting ketone. To aid emulsion formation, the β-keto ester may optionally be dissolved in an organic solvent such as toluene, hexane or heptane, prior to mixing with the dilute alkali solution containing the phase-transfer agent. Preferred reaction times and temperatures for individual esters may vary depending upon the molecular weight of the esters. It appears that the lower the molecular weight of the ester, the lower the temperature and the shorter the reaction time required to complete decarbalkoxylation. Isolation of the ketone is accomplished by extraction of the crude reacton mixture with an appropriate organic solvent, e.g. ethyl ether, ethyl acetate or the like. The crude product is sequentially washed with dilute base and saturated salt solutions. Thereafter, the crude product is dried over a suitable drying agent, filtered and the solvent removed. Final purification may be accomplished by dry-packed silica gel, column chromatography using an appropriate organic solvent. It is within the scope of this invention to prepare the esters using any suitable esterification procedure. In general, the β-keto esters useful in the invention method may be synthesized from their acid chloride using the well-known Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione). The resulting trione is thereafter converted to the desired β-keto ester with the appropriate alcohol. Alternatively, the esters may be prepared by condensing the precursor ketone, which is obtained using the cadmium methyl alkylation of the corresponding acid chloride with diethyl carbonate. Alkylation of the formed β-keto ester may be accomplished using conventional alkylation methodology. For example, the esters may be alkylated with the appropriate alkyl halide in the presence of a suitable base, or with sodium hydride in an appropriate solvent, i.e. THF or benzene. Products prepared from the ketones produced from the method of the invention have a variety of commercial uses including, but not limited to, perfumed, flavor additives, antioxidants, preservatives, inhibitors, intermediates for resins, plastics, adhesives, pharmaceuticals and dyes. Some ketone products such as methylene-linked pyrethroids have demonstrated insecticidal activity. When used, the ketones produced by the method of the invention may be used in solid or liquid form. As will be obvious to one skilled in the arts, the ketones may be used in various compositions of ketones and a carrier. Depending upon the intended use, such compositions may additionally contain conventional additives such as emulsifying agents, wetting agents, binding agents, odorants, stabilizers and the like. The following examples are intended to further illustrate the invention as herein disclosed and not to limit the scope of the invention as defined by the claims. EXAMPLE I Five alkylated β-keto esters having the general formula ##STR3## wherein R 1 is methyl and R 2 is propyl, butyl, hexyl, phenylmethyl or phenylethyl, were converted to the corresponding ketones using the phase-transfer decarbalkoxylation method of the invention. The phase-transfer decarbalkoxylation procedure was as follows: 100 mg of the candidate β-keto ester was added to 5 ml of 10% aqueous potassium hydroxide that contained 0.1% of hexadecyltrimethylammonium bromide. If needed, the ester was dissolved in toluene (100 mg/0.25 ml) to aid micelle formation. The mixture was vigorously stirred under nitrogen and sonication, and heated at 80° C. for 45 minutes. Thereafter, the reaction mixture was acidified with 1N sulfuric acid and the mixture extracted with 25 ml of ethyl ether. The organic phase was dried with MgSO 4 , filtered and concentrated to a light oil. The isolate was purified by dry column chromatography on silica gel using hexane to develop the column. The isolate was quantified and the structure was confirmed by capillary GC/CI-MS (Extrel Corp., Model EL-400-2 fitted with and EL-1000 data system). Yields of the corresponding ketones are recorded in Table I. In all examples, the yield of the ketones exceeded 75%. EXAMPLE II In this example, five alkylated β-keto esters, having the general formula ##STR4## wherein R is 2,2-dimethyl-3-(2-methylpropenyl)cyclopropyl; 2,2-dimethyl 3-(cyclopentanylidenemethyl)cyclopropyl; or 1-(4-chlorophenyl)-2-methyl propyl; and the general formula ##STR5## wherein R is 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropyl, were converted to the corresponding methylene-linked pyrethroids using the method of the invention. TABLE I______________________________________Phase Transfer Catalyzed Decarbalkoxylationof β-Keto Esters (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)β-Keto EsterR.sup.1 R.sup.2 Product Yield (%).sup.a,b______________________________________Me CH.sub.3 CH.sub.2 CH.sub.2 2-hexanone 75.sup.cMe CH.sub.3 (CH.sub.2).sub.3 2-heptanone 85.sup.dMe CH.sub.3 (CH.sub.2).sub.5 2-nonanone 95.sup.dMe C.sub.6 H.sub.5 CH.sub.2 1-phenyl-2-butanone 96.sup.dMe C.sub.6 H.sub.5 CH.sub.2 CH.sub.2 1-phenyl-2-pentanone 90.sup.d______________________________________ .sup.a Quadrex 007 Methylsilicone, 15 M × 0.25 mm; flow = 1.7 cm sec.sup.-1. .sup.b Yields of isolated 2heptanone and 1phenyl-2-butanone were comparable to those suggested by GLC analyses. .sup.c Temp. program: 35° C. for 1 min., 60° C./min. to 80° C., isothermal at 80° C. .sup.d Temp. program: 35° C., 60° C./min. to 80° C., then 60° C./min. to 170° C. The decarbalkoxylation procedure was as follows: A stock reagent was prepared containing 10% of hexadecyltrimethylammonium bromide dissolved in a solution of 10% aqueous potassium hydroxide. 1 g of the candidate β-keto ester was dissolved in a minimum amount of heptane and was added to 50 ml of the reagent. The reaction mixture was sonicated at 80° C. and monitored by analytical TLC. The reaction was usually completed at 90 minutes. The cooled reaction mixture was acidified with dilute hydrochloric acid and then extracted twice with 25 ml of ethyl acetate. The combined organic extracts were washed with 5% sodium bicarbonate and a saturated sodium chloride solution. After drying with MgSO 4 , filtration and removal of the solvent, the isolate was purified by dry-packed silica gel column chromatography using ethyl acetate (3-10%) in hexane to develop the column. The resulting ketones, each a mixture of two optical isomers, were obtained as a colorless oil or semi-solid at -4° C. Yields are recorded in Table II. The novel methylene-linked pyrethroids were all produced in good yield. In all examples the yield exceeded 73%. Accordingly, the method of the invention is useful to convert structurally complicated β-keto esters to ketones in commercially acceptable yields. The novel methylene-linked pyrethroids of Example II were found to exhibit insecticidal activity useful against various agricultural pests. To show the effectiveness of the novel pyrethroids, the insecticidal activities of the compounds of Example II were compared to the activity of phenothrin. Additionally, the activity of the alkylated β-keto ester precursors of the compounds of Example II were compared to that of phenothrin. TABLE II__________________________________________________________________________Phase-Transfer Catalyzed Decarbalkoxylation of Alkylatedβ-Keto Esters (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)__________________________________________________________________________ β-Keto Ester (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)Compound R.sup.1 R.sup.2__________________________________________________________________________ ##STR6## ##STR7##B ##STR8## ##STR9##C ##STR10## ##STR11##D ##STR12## ##STR13##E ##STR14## ##STR15##__________________________________________________________________________Compound Product Yield (%)__________________________________________________________________________ ##STR16## 87B ##STR17## 84C ##STR18## 86D ##STR19## 74E ##STR20## 85__________________________________________________________________________ Activity was determined on the basis of results obtained from the foregoing insecticide tests: INSECTICIDE TEST METHODS Topical Application Test Yellow Mealworm, Tenetrio molitor Linnaeus (YMW), Method of Treatment Formulations were made to contain 100 μg of the candidate compound per 1 μl of acetone/DMSO (1:1 volume ratio) solvent. Topical application was performed with 1 μl calibrated glass micropipet fitted with a rubber bulb. One μl of the formulation was applied on the ventral of the last 3 abdominal segments of each of 5 adults, male and female. The insects were placed in a 9 cm petri dish. Method of Recording Results Mortality and morbidity were recorded after 72 hours. Mode of action may be by contact. Feed Additive Test Fall Armyworm, Spodoptera frugiperda (J. E. Smith) (FAW), Method of Treatment Formulations were prepared to contain 100 μg of the candidate compound per 1 μl of acetone/DMSO (1:1 volume:ratio) solvent. 100 μl of the formulation was incorporated into 100 g of standard hot diet. Treated diets were poured into 1 oz. jelly cups at the rate of 10 g/cup and allowed to cool to room temperature. Method of Recording Results First and fifth instars were weighed and mortality was noted after 7 days. Third instars were allowed to go to adult where mortality, egg production and hatch were recorded. Mode of action may be by stomach poison, contact or vapor. Test concentrations and results are set forth in Table III. Phenothrin used in the above tests was sold under the tradename "Multicide Sumithrin" by McLauglin, Gromley, King Co. of Minneapolis, MN. As shown in Table III, the newly prepared pyrethroids of Example II showed varied activity against both insect species, YMW and FAW, with activity appearing to be least in the early larval stages. With the exception of compounds A and D, none of the ketones expressed an appreciable antifeedent behavior in larvae FAW. Compound A exhibited some mortality activity in FAW larvae but only compounds D and E had significant mortality. Notedly, none of the β-keto esters caused mortality or significant antifeedent activity in the larvae FAW. Looking at the YMW, all the ketones and their alkylated β-keto esters caused 100% mortality in the adult YMW. Only compound D caused 100 percent mortality in the YMW pupae. The remaining compounds were for the most part inactive against the YMW pupae, with only compounds A, B and D 1 showing a minimal activity. It is understood that modifications and variations may be made to the foregoing disclosure without departing from the spirit and scope of the invention. TABLE III______________________________________Insect Bioassay of Methylene-Linked Pyrethroids.sup.aMortality/Activity at 100 PPM.sup.b Fall Army Yellow Meal Worm (FAW) Worm (YMW)Compound Larvae.sup.c (%).sup.d Pupae Adult______________________________________A.sup.1.spsp.e 0(71) 0 100B.sup.1.spsp.e 0(70) 0 100C.sup.1.spsp.e 0(70) 0 100D.sup.1.spsp.e 0(80) 20 80E.sup.1.spsp.e 0(75) 0 100A 30(49) .sup. 20(.6).sup.f 100B 0(90) 20 100C 0(84) 0 100D 80(68) 100 100E 50(20) 0 100PHENOTHRIN 100(00) 100 100______________________________________ .sup.a Only trans geometric isomers of the compounds listed were used in the above test. .sup.b Topical application. .sup.c 1st Instar, diet application. .sup.d Relative antifeedant activity (% of normal growth). .sup.e A.sup.1, B.sup.1, C.sup.1, D.sup.1, and E.sup.1 represents alkylated β-keto esters precursors ketones A, B, C, D and E. .sup.f JH rating.

An improved method for the decarbalkoxylation of alkylated β-keto esters to obtain high yields of ketones. In accordane with the method, decarbalkoxylation of alkylated β-keto esters is accomplished by heating the esters in the presence of dilute aqueous alkali and an effective amount of a phase-transfer agent. The method produces commercially practical yields of ketone in a manner which is facile, economical and environmentally safe. Novel methylene-linked pyrethroid ketones produced from the improved method exhibit insecticidal activity against various agricultural pests.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to, and claims priority to, Korean patent application KR 10-2007-0099473, filed on Oct. 2, 2007, the entire contents of which being incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device, computer program product and method of inputting a character in a touch screen device, and more specifically, to a method of inputting a character, in which a touch area is partitioned into a plurality of array positions, and one or more characters are assigned to each of the partitioned array positions, so that if one of the partitioned array positions is touched, the characters assigned to the touched array positions are enlarged and rearranged on the touch screen to allow a user to select an input character. 2. Description of the Related Art As portable electronic devices are miniaturized in size and in pursuit of a simple design recently, the portable electronic devices are gradually provided with a touch screen in place of mechanical key buttons that require a certain fixed space. Positions and settings of input buttons of an input device using a touch screen may be freely set or modified. Accordingly, recently manufactured portable electronic devices receive most of inputs through a touch pad, except only a minimum button inputs. Inputting characters is not an exception, and input of characters is also accomplished by touching the touch screen. When characters are inputted through a conventional touch screen, all characters are arranged on the touch screen, and a character touched by a user is inputted among the arranged characters. However, the prior art described above has following problems. That is, since the characters are many in number, and thus the width of the touch screen occupied by a character is narrow if all the characters are arranged on the touch screen, there is a problem in that readability of the characters is lowered and it becomes also difficult to arrange the characters. Furthermore, since a touch area occupied by a character is narrow according to the prior art, when a user who desires to input the character inputs the character, the user may touch adjacent other characters together and generate an input error, or may suffer from incorrect touches in using the touch screen. SUMMARY OF THE INVENTION The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a touch screen device, a computer program product and a method of inputting a character therein, in which input of characters is accomplished in multiple steps making use of versatility of the touch screen. Another object of the present invention is to provide a touch screen device, a computer program product and a method of inputting a character therein, in which representative characters are arranged on the touch screen, and when one of the representative characters is selected, characters subordinated to the selected character are displayed to receive a character. According to an aspect of the present invention for achieving the objects, there is provided a device, computer program product and method of inputting a character on a touch screen receiving a character by sensing a touch of a touch panel. The method comprises the steps of: partitioning a touch area of the touch panel into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; sensing an expansion event of selecting one among the array positions; dividing the touch area into a plurality of selection positions and assigning the characters assigned to the array position selected by the expansion event to the respective selection positions; sensing a selection event of selecting one among the selection positions; and recognizing the character assigned to the selection position selected by the selection event as an input character. At this time, the expansion event may be generated by a touch input of the user, and the selection event is generated by a release of the touch. Also, the expansion event and the selection event may be generated by a touch input of the user. In addition, if the selection event is generated on the touch panel out of the selection positions, the selection event may be recognized as a command for canceling input of a character. At this time, the array positions may be formed by dividing the touch area into a matrix form of n×m. In addition, if two or more characters are assigned to the selection positions, the selection positions may be formed to expand in directions including one or more of up, down, left and right sides from a position where the expansion event is generated. At this time, n and m are 3, respectively; and in the array positions (AP), three or less characters may be assigned to AP(1, 1), four or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(1, 3), four or less characters may be assigned to AP(2, 1), five or less characters may be assigned to AP(2, 2), four or less characters may be assigned to AP(2, 3), three or less characters may be assigned to AP(3, 1), four or less characters may be assigned to AP(3, 2), and three or less characters may be assigned to AP(3, 3). In addition, the selection positions may be formed at the position of AP(1, 1) and to expand to the down and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the down, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the down and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up, down and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). The input character is a Korean letter, and Korean consonants and vowels may be sequentially assigned to the array positions. Here, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2), and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime, n and m are 2, respectively; and in the array positions (AP), three or less characters may be assigned to AP(1, 1), three or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(2, 1), and three or less characters may be assigned to AP(2, 2) At this time, the input character is a numeral, and Arabic numerals may be sequentially assigned to the array positions. Then, in the array positions (AP), 1, 2 and 3 may be assigned to AP(1, 1); 4, 5 and 6 may be assigned to AP(1, 2); 7, 8 and 9 may be assigned to AP(2, 1); and 0 may be assigned to AP(2, 2). In the meantime, if two or more characters are assigned to the selection position, the selection position may be formed to expand in directions including one or more of up, down and left sides from a position where the expansion event is generated. Here, n and m are 3, respectively; and in the array positions (AP), two or less characters may be assigned to AP(1, 1), three or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(1, 3), three or less characters may be assigned to AP(2, 1), four or less characters may be assigned to AP(2, 2), four or less characters may be assigned to AP(2, 3), two or less characters may be assigned to AP(3, 1), three or less characters may be assigned to AP(3, 2), and three or less characters may be assigned to AP(3, 3). Then, the selection positions may be formed at the position of AP(1, 1) and to expand to the down side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and down sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left and down sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and down sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). In addition, the input character is an English letter, and English letters may be assigned to the array positions in sequence of a QWERTY array. Then, in the array positions, Q and W may be assigned to AP(1, 1); E, R and T may be assigned to AP(1, 2); Y, U and I may be assigned to APP(1, 3); O, P and A may be assigned to AP(2, 1); S, D, F and (may be assigned to AP(2, 2); U, J, K and L may be assigned to AP(2, 3); Z and X may be assigned to AP(3, 1); C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). Further, in the array positions, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime if two or more characters are assigned to the selection position, the selection position may be formed to expand in directions including one or more of up, left and right sides from a position where the expansion event is generated. Then, n and m are 3, respectively; and in the array positions 70 , two or less letters may be assigned to AP(1, 1), three or less letters may be assigned to AP(1, 2), two or less letters may be assigned to AP(1, 3), three or less letters may be assigned to AP(2, 1), four or less letters may be assigned to AP(2, 2), three or less letters may be assigned to AP(2, 3), three or less letters may be assigned to AP(3, 1), four or less letters may be assigned to AP(3, 2), and two or less letters may be assigned to AP(3, 3). Then, the selection positions may be formed at the position of AP(1, 1) and to expand to the right side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, Q and W may be assigned to AP(1, 1); E, R and T may be assigned to AP(1, 2); Y and U may be assigned to AP(1, 3); I, O and P may be assigned to AP(2, 1); A, S, D and F may be assigned to AP(2, 2); G, H and J may be assigned to AP(2, 3); K, L and Z may be assigned to AP(3, 1); X, C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). Alternatively, in the array positions, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In addition, n and m are 3, respectively; three or less letters may be assigned to AP(1, 1), four or less letters may be assigned to AP(1, 2), three or less letters may be assigned to AP(1, 3), two or less letters may be assigned to AP(2, 1), four or less letters may be assigned to AP(2, 2), three or less letters may be assigned to AP(2, 3), two or less letters may be assigned to AP(3, 1), three or less letters may be assigned to AP(3, 2), and two or less letters may be assigned to AP(3, 3). Then, the selection positions 90 may be formed at the position of AP(1, 1) and to expand to the up and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the up and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up side therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, Q, W and E may be assigned to AP(1, 1); R, T, Y and U may be assigned to AP(1, 2); I, O and P may be assigned to AP(1, 3); A and S may be assigned to AP(2, 1), D, F, G and H may be assigned to AP(2, 2); J, K and L may be assigned to AP(2, 3); Z and X may be assigned to AP(3, 1); C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). In addition, n and m are respectively 3, and one character may be assigned to AP(1, 1), two or less letters may be assigned to AP(1, 2), two or less letters may be assigned to AP(1, 3), two or less letters may be assigned to AP(2, 1), three or less letters may be assigned to AP(2, 2), two or less letters may be assigned to AP(2, 3), two or less letters may be assigned to AP(3, 1), four or less letters may be assigned to AP(3, 2), and three or less letters may be assigned to AP(3, 3). Then, the selection position may be the position of AP(1, 1) if the expansion event is generated at AP(1, 1); and the selection positions may be formed at the position of AP(1, 2) and to expand to the left side therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the left side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the left side therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left, and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, an “Add a stroke” button may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime, the present invention provides a method of inputting a character on a touch screen receiving a character by sensing a touch of a touch panel. The method comprises the steps of: partitioning a touch area of the touch screen into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; enlarging and rearranging the characters, which are assigned to one of the partitioned array positions selected by a user, on the touch screen; and recognizing one of the rearranged characters reselected by the user as an input character. In addition, the assigned characters may be arranged in the partitioned array position so that one of the characters is arranged at a center and the other characters are arranged at one or more positions of up, down, left and right sides of the character arranged at the center. At this time, the character arranged at the center may be set to be larger than the other characters within the same partitioned array position in common. Further, the expansion may be performed from the character arranged at the center in directions where the other characters are arranged. Furthermore, the rearrangement of characters may be performed so that one of the characters is arranged in each of the expanding directions. In addition, the present invention provides a touch screen device, which comprises: a touch panel controller for sensing a touch and a touch release of a touch panel; a display controller for outputting an image of a character corresponding to the touch or touch release on a screen; and a control unit for receiving a result of the sensing from the touch panel controller and controlling the display controller to output an image of a character corresponding to the result of the sensing, and receiving the corresponding character depending on the result of the sensing, wherein the control unit partitions a touch area of the touch screen into a plurality of array positions to assign one or more characters to each of the partitioned array positions, rearranges the characters, which are assigned to one of the partitioned array positions selected by a user, on the touch screen, and recognizes one of the rearranged characters reselected by the user as an input character. According to the touch screen device and the method of inputting a character therein according to the present invention described above, the following effects can be expected. That is, since only representative characters are initially arranged and displayed on the touch screen, a touch area assigned to a character is widened, and thus it is advantageous in that readability of characters of a user is enhanced. Furthermore, since a touch area assigned to a character is widened as described above, the present invention has an advantage in that an input error occurring by touching a character together with adjacent characters can be prevented when a user inputs the character. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a touch screen device according to a specific embodiment of the present invention; FIG. 2 is a flowchart illustrating a method of inputting a character in the touch screen device according to the specific embodiment of the present invention; FIGS. 3 a to 3 d are exemplary views showing operating states of a first application example of the present invention; FIGS. 4 a to 4 b are exemplary views showing operating states of a second application example of the present invention; FIGS. 5 a to 5 d are exemplary views showing operating states of a third application example of the present invention; FIG. 6 is an exemplary view showing an operating state of a fourth application example of the present invention; FIG. 7 is an exemplary view showing an operating state of a fifth application example of the present invention; FIG. 8 is an exemplary view showing an operating state of a sixth application example of the present invention; FIGS. 9 a to 9 b are exemplary views showing operating states of a seventh application example of the present invention; and FIG. 10 is an exemplary view showing an operating state of an eighth application example of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of the touch screen device and the method of inputting a character therein according to the present invention described above will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a touch screen device according to a specific embodiment of the present invention. As shown in the figure, the touch screen device of the present invention is provided with a touch panel 10 for sensing a touch of a user. The touch panel 10 may be a variety of known touch panels of a piezoelectric type, capacitive type, or the like. Then, the touch panel 10 is connected with a touch panel controller 20 for sensing a touch on the touch panel 10 and the position of the touch and controlling the operation of the touch panel 10 . That is, if there is a touch input of a user on the touch panel 10 , the touch panel 10 converts the touch into an electrical signal and transfers the electrical signal to the touch panel controller 20 , and the touch panel controller 20 recognizes the touch input (including touch release) and calculates an input position. In the meantime, the touch panel is combined with a display screen 30 . The display screen is a general display device, such as a liquid crystal display (LCD), a plasma display panel (PDP), a cathode ray tube (CRT), or the like, which is a part for displaying an image to be outputted to a user. In addition, in the specific embodiment of the present invention, the display screen 30 , which is a part for displaying a touch position to the user, displays a character to be inputted when the touch panel is touched and displays an area where the character is assigned. Meanwhile, the display screen 30 is connected to a display controller 40 for controlling the display screen 30 . The display controller 40 is a part for changing an image to be displayed on the display screen 30 depending on a command of a control unit 50 and an input mode that will be described below. The control unit 50 for controlling the touch panel controller 20 and the display controller 40 is connected to the touch panel controller 20 and the display controller 40 . That is, the control unit 50 initially arranges and displays characters to be inputted on the display and then changes and displays arrangement of the characters in response to a user's input. In addition, the control unit 50 serves to receive the fact and the position of the touch input (including a touch release input) of the user from the touch panel controller 20 , search for a corresponding command, and change the display and input mode according to the corresponding command. At this time, a specific example describing how the control unit 50 operates in response to a user's input will be described below. In the meantime, the control unit 50 is connected with a storage unit 60 for storing information on how the control unit 50 controls the touch panel controller 20 and the display controller 40 depending on a user's touch input. Hereinafter, a specific control method of the control unit 50 for controlling the touch panel controller 20 and the display controller 40 will be described. Here, the control of the touch panel 10 and the display controller 40 is controlling the touch panel 10 and the display screen 30 through the touch panel controller 20 and the display controller 40 . Before describing the control method of the control unit 50 , some terminologies are defined for convenience of explanation, and the method will be described using some defined terminologies. Examples of referenced items may be found in the figures. First, an array position 70 is a partitioned area to which a character is assigned in a character input mode. Then, an expansion event is an input command for selecting one of array positions 70 . In addition, a selection position 90 is an area on the touch screen, where a character assigned to the selected array position 70 is rearranged when the expansion event is inputted. Then, a selection event is an event of selecting a character by selecting one of selection positions 90 . At this time, the character selected and inputted by the selection event is referred to as an input character. First, in the character input mode, the control unit 50 divides the touch screen into a plurality of array positions 70 . Then, one or more characters are assigned to each of the array positions 70 . At this time, the array positions 70 may be arranged in a rectangular form of n×m or in a square form of n×n. Then, if an expansion event is sensed from one of the array positions 70 , the control unit 50 rearranges the characters assigned to the sensed array position 70 , from which the expansion event is sensed, on the selection positions 90 . At this time, the expansion event is generated when the user touches a corresponding area. In the meantime, upon observing a response state of the controller according to the user's touch input, if the touch input is normally made within an area, the character within the area is recognized to be inputted without a problem. However, if two adjacent array positions are touched (when a border line is touched), first, 1) it may be determined that any touch is not made. Alternatively, 2) the touched areas are compared, and an array position which is comparatively broader among the two touched array positions may be determined as being selected. Alternatively, 3) a message for requesting to confirm which of the two array positions is the selected array position may be displayed to the user. Then, the selection positions 90 are set as many as the characters assigned to the array position 70 selected by the expansion event. The selection positions 90 may be set randomly or with a specific rule. Specific examples of the rule for setting the selection positions 90 will be described. The selection positions 90 may be formed to expand in directions including one or more of the up, down, left, and right sides from the point where the expansion event is generated; in directions including one or more of the up, down, and left sides from the point where the expansion event is generated; or in directions including one or more of the up, left, and right sides from the point where the expansion event is generated. Alternatively, the selection positions 90 may be formed to expand in directions including one or more of the up and left sides from the point where the expansion event is generated. If the selection positions 90 are formed to expand in four directions of up, down, left, and right sides, there is an advantage in that the number of the selection positions 90 that can be arranged on the touch screen is increased. Then, if the selection positions 90 are formed to expand in two directions of up and left sides, there is an advantage in that the screen can be prevented from being shielded with the user's hand when the user touches the touch screen. It is apparent that this is for general right-handed users, and a direction to the right can be set instead of a direction to the left for left-handed users. However, in this case, there is a disadvantage in that the number of selection positions 90 that can be arranged is small. Accordingly, a method into which the aforementioned methods are combined may be used in consideration of the number of characters to be arranged, and the second and third methods are examples of the combined method. Then, if a selection event is generated from the touch panel 10 , the control unit 50 recognizes a character assigned to the selection position 90 where the selection event is generated as the input character and then processes the input. At this time, if the selection event is generated from an area out of the selection positions 90 , the control unit 50 recognizes the selection event as a command for canceling the input character and then cancels the input of the character. In the meantime, if the input of the character is completed or cancelled, the control unit 50 restores the touch screen to a waiting state of an initial character input mode. Here, the input event may be generated by a touch release of the user or by touching the touch panel 10 by the user. That is, the selection positions 90 are set by an expansion event generated by touching the array position 70 , and the selection event may be generated by releasing the touch after selecting one of the selection positions 90 by dragging the touch while the touch is maintained. Alternatively, the expansion event and the selection event may be generated by separate touches. In the meantime, the control unit 50 may be connected to the storage unit 60 for storing information on settings of the array positions 70 and the selection positions 90 and information on settings of expansion events and selection events. The storage unit 60 stores forms of the array positions 70 differently set by the type of characters, such as English characters, Korean characters, numerals, and the like, as well as assigned characters, display information, and the like. Then, the storage unit stores an execution command corresponding to an expansion event for each of the array positions 70 when the expansion event is inputted. In addition, the storage unit also stores information on the form of each selection position 90 and characters arranged on the selection position. The storage unit also stores an execution command corresponding to a selection event for each of the selection position 90 . Hereinafter, the operation of the touch screen device according to the present invention will be described in detail through the method of inputting a character. FIG. 2 is a flowchart illustrating a method of inputting a character in the touch screen device according to the specific embodiment of the present invention. As shown in the figure, the method of inputting a character according to a specific embodiment of the present invention first determines whether an expansion event is sensed by a user. The expansion event is generated by a user's touch as described above (step S 10 ). The present invention, which relates to a method of inputting a character on a touch screen, will be described basically assuming that the touch screen device is in a character input mode. At this time, the touch screen is in a character input waiting state, and the array positions 70 are set as described above. Next, the control unit 50 searches for execution information corresponding to the position where the expansion event is generated (step S 120 ). At this time, the execution information can be searched from the information stored in the storage unit 60 . The execution information includes all of setting information on the manner of arranging the selection positions 90 in correspondence with the expansion event and on characters to be assigned to each of the arranged selection positions 90 together with the manner of assigning the characters to the selection positions. Then, the touch panel 10 and the display are set again based on the searched execution information (step S 130 ). That is, the selection positions 90 are arranged on the touch screen, and corresponding characters are assigned. Thereafter, it is determined whether a selection event is inputted by the user (step S 140 ). The selection event may be a touch or a touch release of the user as described above. After the selection event is sensed, the input position of the selection event is determined (step S 150 ). At this time, it is determined whether the input position of the selection event is within the selection positions 90 . If the input position of the selection event is within the selection positions 90 , a character set to the position where the selection event is generated is recognized as an input character, and the character is inputted (step S 170 ). If the input character is inputted or the selection event is generated out of the selection positions 90 , display settings of the touch panel 10 and the display screen 30 are restored to the settings of the character input waiting state (step S 180 ). At this time, the restoration means returning the settings to the settings of the initial character input waiting state. Thereafter, it is determined whether the character input mode is released, and execution of the present invention is terminated if the character input mode is released, whereas the touch screen device waits for input of a new character if the character input mode is continued (step S 190 ). Here, the method of combining inputted characters and constructing a syllable, a word, or the like is the same as a known prior art. Hereinafter, examples of the present invention, in which the specific embodiment of the present invention is practically employed and operates on a touch screen, will be described in detail with reference to the accompanying drawings. FIGS. 3 a to 3 d are exemplary views showing operating states of a first application example of the present invention. FIG. 3 a is a view showing the array positions 70 of the first application example. Korean letters are inputted in the first application example, and the array positions 70 are formed in a 3×3 matrix. At this time, the array positions (AP) 70 are respectively expressed as AP (1, 1) to AP (3, 3) for convenience of explanation. In the array positions 70 , three or less letters are assigned to AP(1, 1), four or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(1, 3), four or less letters are assigned to AP(2, 1), five or less letters are assigned to AP(2, 2), four or less letters are assigned to AP(2, 3), three or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and three or less letters are assigned to AP(3, 3). Then, Korean consonants and vowels are sequentially assigned to the array positions 70 . In other embodiments, other non-English symbols (e.g., Arabic, Chinese, Kangi, etc.) may be used. Thus, a person conversant with these non-English alphabets may practice the invention in the alphabet of their choice. Upon describing an example of arranging the Korean letters, as shown in FIG. 3 a , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). At this time, although there are a variety of methods for displaying the letters, a representative letter among the assigned letters may be displayed in a large size, and the other letters may be arranged in a small size, as shown in the figure. At this time, if one of the array positions 70 is touched, selection positions 90 are set in response to the touch. The selection positions 90 are formed to expand in the directions including one or more of the up, down, left and right sides from the position where the expansion event is generated. Upon describing the expansions one by one, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the down and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the down, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the down and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up, down and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). For example, if is touched as shown in FIG. 3 b , five selection positions 90 are set by expanding to the up, down, left, and right sides from as shown in FIG. 3 c , and and are respectively assigned to the selection positions. Thereafter, while being touched on , a stylus pen 80 is dragged to the position of . Then, if the stylus pen 80 releases the touch at the position of (a selection event is generated), is inputted as shown in FIG. 3 d . A finger or another device may be used in place of the stylus pen 80 . At this time, it is apparent that if the stylus pen 80 releases the touch out of the selection positions 90 (at the shaded area), the input of the letter is cancelled, and the touch screen device is transferred to the initial waiting mode ( FIG. 3 a ). In addition, the selection event may be generated by separate touches as described above. FIGS. 4 a to 4 b are exemplary views showing operating states of a second application example of the present invention. FIG. 4 a is a view showing the array positions 70 of the second application example. Numerals are inputted in the second application example, and the array positions 70 are formed in a 2×2 matrix. In the array positions 70 , three or less characters are assigned to AP(1, 1), three or less characters are assigned to AP(1, 2), three or less characters are assigned to AP(2, 1), and three or less characters are assigned to AP(2, 2). Then, as shown in FIG. 4 a , in the array positions 70 , numerals 1 , 2 , and 3 are assigned to AP(1, 1); numerals 4 , 5 , and 6 are assigned to AP(1, 2); numerals 7 , 8 , and 9 are assigned to AP(2, 1); and numeral 0 is assigned to AP(2, 2). At this time, the arrangement of the selection positions 90 is set in the same manner as the first application example. Then, if “11” is selected among the array positions 70 , selection positions are set as shown in FIG. 4 b. Then, a selection event is generated, and a character is inputted in the same manner as described above. FIGS. 5 a to 5 d are exemplary views showing operating states of a third application example of the present invention. FIG. 5 a is a view showing the array positions 70 of the third application example. English letters are inputted in the third application example, and the array positions 70 are formed in a 3×3 matrix. At this time, in the array positions 70 , two or less letters are assigned to AP(l, 1), three or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(T, 3), three or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), four or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), three or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). English letters are arranged in the sequence of the QWERTY array, wherein the sequence of the QWERTY array means the sequence of letters arranged on a keyboard. In the array positions 70 , Q and W are assigned to AP(1, 1); E, R and T are assigned to AP(1, 2); Y, U and I are assigned to AP(1, 3); 0, P and A are assigned to AP(2, 1); S, D, F and G are assigned to AP(2, 2); H, J, K and L are assigned to AP(2, 3); Z and X are assigned to AP(3, 1); C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). At this time, if one of the array positions 70 is touched, selection positions 90 are set in response to the touch. The selection positions 90 are formed to expand in one or more directions including the up, down and left sides from the position where the expansion event is generated. Upon describing the expansions one by one, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the down side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and down sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left and down sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and down sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). For example, if “E” is touched as shown in FIG. 5 b , four selection positions 90 are set by expanding to the left, right and down sides from “E” as shown in FIG. 5 e , and E, R, Y and T are respectively assigned to the selection positions. Thereafter, while being touched on “E”, the stylus pen 80 is dragged to the position of “T”. Then, if the stylus pen 80 releases the touch at the position of “T” (a selection event is generated), “T” is inputted as shown in FIG. 5 d. At this time, it is apparent that if the stylus pen 80 releases the touch out of the selection positions 90 , the input of the letter is cancelled, and the touch screen device is transferred to the initial waiting mode, which is the same as described above. In addition, the selection event may be generated by separate touches as described above. FIG. 6 is an exemplary view showing an operating state of a fourth application example of the present invention. Korean letters are inputted in the fourth application example in the same manner as the third application example, and Korean consonants and vowels are sequentially assigned. In the array positions 70 , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). FIG. 7 is an exemplary view showing an operating state of a fifth application example of the present invention. At this time, the fifth application example is formed in a 3×3 matrix, and in the array positions 70 , two or less letters are assigned to AP(1, 1), three or less letters are assigned to AP(1, 2), two or less letters are assigned to AP(1, 3), three or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), three or less letters are assigned to AP(2, 3), three or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). Upon describing further specifically, in the array positions 70 , Q and W are assigned to AP(1, 1); E, R and T are assigned to AP(1, 2); Y and U are assigned to AP(1, 3); I, O and P are assigned to AP(2, 1); A, S, D and F are assigned to AP(2, 2); G, H and J are assigned to AP(2, 3); K, L and Z are assigned to AP(3, 1); X, C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). At this time, although it is not shown in the figure, the selection positions 90 are formed to expand in one or more directions including the up, left and right sides from the position where the expansion event is generated. Upon describing further specifically, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the right side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). In the meantime, FIG. 8 is an exemplary view showing an operating state of a sixth application example of the present invention, wherein the sixth application example is an example where Korean letters are assigned in the same manner as the fifth application example. In the sixth application examples in the array positions 70 , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). FIGS. 9 a to 9 b are exemplary views showing operating states of a seventh application example of the present invention. English letters are arranged in the seventh application example, and the array positions 70 are formed in a 3×3 matrix, in which three or less letters are assigned to AP(1, 1), four or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(1, 3), two or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), three or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), three or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). In the array positions 70 , Q, W and E are assigned to AP(1, 1); R, T, Y and U are assigned to AP(1, 2); I, O and P are assigned to AP(1, 3); A and S are assigned to AP(2, 1); D, F, G and H are assigned to AP(2, 2); J, K and L are assigned to AP(2, 3); Z and X are assigned to AP(3, 1); C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). In the meantime, in the seventh application example, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the up and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the up and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up side therefrom if the expansion event is generated at AP(3, 3). For example, if “R” is touched among the array positions 70 as shown in FIG. 9 b , selection positions 90 are set to the up, left and right sides from “R”, and T, Y and U are respectively assigned to the up, left and right sides. Then, the selection event and the method of inputting a character are the same as described above. FIG. 10 is an exemplary view showing an operating state of an eighth application example of the present invention. In the eighth application example, the array positions 70 are formed in a 3×3 matrix, in which one character is assigned to AP(1, 1), two or less letters are assigned to AP(1, 2), two or less letters are assigned to AP(1, 3), two or less letters are assigned to AP(2, 1), three or less letters are assigned to AP(2, 2), two or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and three or less letters are assigned to AP(3, 3). At this time, the input characters are Korean letters, and Korean consonants and vowels are sequentially assigned to the array positions 70 . Then, in the array positions 70 , an “Add a stroke” button is assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). The “add a stroke” button allows a user to add a stroke symbol as a displayed symbol. Other symbols may be used as an added symbol. Although the selection positions 90 are intended to expand to the up and left sides from the selected array position 70 in the eighth application example, four letters are assigned to AP(3, 2) in order to set an array for convenience of users, and selection positions 90 are set to the up, left and right sides only from the selected array position. It is apparent that the position of the selection position 90 to which four letters are assigned may be differently set. Accordingly, in the eighth application example, the selection position 90 is the position of AP(1, 1) if the expansion event is generated at AP(1, 1); and the selection positions 90 are formed at the position of AP(1, 2) and to expand to the left side therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the left side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the left side therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left, and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). In the specific embodiment of the invention described above, it has been described that expansion directions and the number of the selection positions are predetermined, and accordingly, the number of characters assigned to each of the array positions and the forms of the array positions are determined. However, according to another aspect of the present invention, the touch screen is partitioned into array positions of a matrix form, and one or more characters are assigned to each of the partitioned array positions. At this time, the characters are arranged so that relatively large-sized one of the characters is arranged at the center of the partitioned array position, and the other characters are arranged at one or more positions of the up, down, left and right sides centering on the large-sized character. In addition, expansion of the array position depends on the directions and the number of the assigned characters. That is, the expansion is performed from the position of the character arranged at the center toward the directions where the other characters are arranged, and the other characters is respectively assigned to the expanding selection positions and displayed on the selection position. At this time, it is apparent that the characters may be displayed in the same size. The touch panel of the present invention may be included in a wireless communication device (e.g., cell phone) or a personal data assistant (PDA) configured to communicate with another device via a network (e.g., a CDMA, Bluetooth or other wireless network). Various embodiments described herein may be implemented in a computer-readable medium using, for example, computer software, hardware, or some combination thereof. For a hardware implementation, the embodiments described herein may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a selective combination thereof. For a software implementation, the embodiments described herein may be implemented with separate software modules, such as procedures and functions, each of which perform one or more of the functions and operations described herein. The software codes can be implemented with a software application written in any suitable programming language and may be stored in memory, and executed by a controller or processor. The scope of the present invention is not limited to the embodiments described above but is defined by the appended claims. It will be apparent that those skilled in the art can make various modifications and changes thereto within the scope of the invention defined by the claims.

A device, computer program product and method of inputting a character in a touch screen device, in which a touch area is partitioned into a plurality of array positions, and one or more letters are assigned to each of the partitioned array positions. The method comprises the steps of: partitioning a touch area of the touch panel into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; sensing an expansion event of selecting one among the array positions; dividing the touch area into a plurality of selection positions and assigning the characters assigned to the array position selected by the expansion event to the respective selection positions; sensing a selection event of selecting one among the selection positions; and recognizing the character assigned to the selection position selected by the selection event as an input character.

RELATED APPLICATIONS [0001] The present application claims the benefit of U.S. Provisional Patent Application S. No. 60 / 313 , 035 , filed on Aug. 16, 2001 titled “A METHOD FOR CONTROLLING IP APPLICATIONS DURING NETWORK CHANGES THAT RESULT IN RESOURCE SHORTAGES” which is hereby expressly incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to communications session and resource management and, more particularly to methods and apparatus for enabling a mobile node to maintain a communications session despite a decrease in resources, e.g., temporary reduction or loss of bandwidth, used to support the communications session. BACKGROUND OF THE INVENTION [0003] Many user applications require a minimum amount of resources, e.g., communications bandwidth, to be useful. One example is traditional voice telephony that below either a target minimum bandwidth or above a maximum delay becomes unusable. During call set-up in traditional fixed telecom networks, a signaling channel first checks that sufficient resources exist between the caller and callee before admitting the call and ringing the callee in the case of voice. If there is insufficient resource then the call is refused with a network busy signal. Once admitted, calls are usually dropped by the network only if equipment fails or due to pre-emption mechanisms such as emergency over-rides. This model has continued into much of the traditional wireless industry where the resources are checked and then only dropped under network control as before. A new source of network failures though in wireless networks is that the hand-off between cells can result in a dynamic step-change in network conditions (new cell being fully occupied) that can cause the call to be dropped. [0004] In existing cellular systems the media flow (e.g. voice and/or audio) and call control channel are tightly coupled resulting in both the call signaling and call media forcibly being dropped at the same time. This prevents the signaling channel from being used to advise the mobile node of the resource problem and give the MN options as to how things should proceed. In next generation IP data applications, the session control signaling, e.g., session signaling which may be implemented using, e.g., Session Initiation Protocol-“SIP” and media planes used to implement data transfer and data application signal using, e.g., Realtime Transfer Protocol-“RTP”, are designed to be distinct and separable. This allows, in some IP based communications systems, session control signaling and data signaling to be controlled independently. [0005] In IP based applications, multiple user of an IP device may interact as a group, e.g., as part of a group game session. Dropping group members due to the temporary loss of bandwidth by an individual member can result in an inconvenient and un-enjoyable experience for the remaining group members. The sudden loss of a player may leave the other players without notice as to the dropped player's absence. Furthermore, the need for a dropped player to establish a new communications session in order to rejoin the group can result in relatively lengthy delays even after bandwidth has been restored to the dropped member. It would be far more desirable if a group member, e.g., player, subject to a sudden decrease in bandwidth could notify the other group members of a temporary absence and simply halt data communications without terminating the control portion of the group communications session. Thus, the other group members would be aware of the temporary absence of the group member subject to temporary bandwidth limitations and the group member can reestablish the data portion of the connection as soon as bandwidth is restored without having to establish an entirely new communications session. [0006] In some cases, sudden decreases in bandwidth may be due to re-allocation of bandwidth in a cell in which a mobile node is operating or the previous allocation of bandwidth to other mobile communications users in a cell into which a mobile node is traveling. When confronted which such bandwidth problems, which would normally result in a connection being dropped, it would be nice to give the user who is about to have a connection dropped the opportunity to upgrade the user's priority, e.g., by paying a premium, to maintain an existing communications session. In this manner, a user could prevent the loss of the connection by selecting, e.g., to pay a premium to have the connection maintained. Unfortunatley, existing communications systems do not offer a mobile node user this opportunity. [0007] In view of the above discussion, it is apparent that there is a need for methods and apparatus that would allow a communication session to be maintained even when changes in conditions, e.g., due to a mobile device's poor location or signal interference, result in insufficient resources to continue the data portion of the communications session. In addition, there is a need for providing users of mobile devices an opportunity upgrade their relative priority in terms of resource allocation before dropping a connection due to a resource request from a mobile device having a higher priority or because of the previous allocation of the required resources to another device. SUMMARY OF THE INVENTION [0008] The present invention relates to communications session and resource management and, more particularly to methods and apparatus for enabling a mobile node to maintain a communications session despite a decrease, e.g., temporary reduction or loss of bandwidth, used to support the communications session Control signaling often requires far less bandwidth than data transmission. In addition, in some system implementations, control signals used to support a communications session are transmitted on different channels than the channels used to transmit data, e.g., voice, text, game information, etc., as part of a communications session. Accordingly, even when there is insufficient resources to maintain the data portion of a communications session, it is possible to continue the control signaling and thus the communications session, e.g., at a reduced data rate or without the ability to transfer data for a period of time. When the bandwidth required to transfer data becomes available, the data portion of the communications session is restored to normal without the need to re-establish the session. This is in sharp contrast to having to close the session and later restart the session when resources are once more available, as done in the prior art systems. [0009] Prior to dropping a connection, or placing a session into a hold or other state requiring reduced bandwidth, in accordance with one feature of the present invention a mobile node user is provided an option to upgrade the user's resource allocation priority. By selecting the upgrade option the user is provided with the resources, e.g., bandwidth, required to maintain the session and the communications network operator is provided the opportunity to generate revenue by charging a priority upgrade service charge or other type of fee. [0010] Combining session and resource tracking is used in accordance with the invention in a mobile node (MN) and/or basestation in a dynamic network resource environment to control reactions to resource shortages. The session that is to experience a resource shortage is either detected by the MN, or communicated to the MN where session signaling is used to modify the session according to MN and basestation policy/configuration. The basestation can alternatively modify the session itself with all the session peers, on behalf of the MN. The specific new reaction to resource shortages, in accordance with the invention, is to place the session on hold thereby freeing network resources to be used by other nodes. However, as part of the session hold operation, the session state is maintained in the peers of the node subject to the resource shortage, and placed in a hold state where some form of local (to the MN) hold action can be performed for the user such as playing a tone, showing an advert, undertaking a local only game play phase etc. This is often preferable to dropping the session, as is generally the case in dynamic environments. This is particularly the case when the period of resource loss is likely to be short and the session modifications required to transition the session back into an on-state will require less overhead than restarting the session. [0011] In accordance with one feature of the invention, before having resources removed, the basestation can provide the MN with an opportunity to upgrade the priority of its resource request compared to the resource allocation priority of other users in the same cell. In such embodiments a resource auction is conducted to decide which MN actually loses its resources. [0012] While applicable to communications involving various types of data, e.g., voice, text, video, messaging, collaborative distributed applications such as game information, etc., the benefits of the present invention will be explained in various examples in the current application using a voice communications session, e.g., a telephone call, as an example. [0013] Typically, in accordance with the invention, a communications session, e.g., IP telephone call, will be set-up with a minimum resource requirement, below which the session will be ineffective (e.g., (codec) coder/decoder bandwidth requirement). In the case of an IP telephone call communication session, this information would typically be communicated using SIP preconditions and installed using ReSerVation Protocol (RSVP) or similar signaling or preconfigured admission control techniques. During or following call set-up in a cell, a session may fail due to insufficient instantaneous resources although those resources might be available very shortly due to a cell change or the action of other MNs in the cell. In addition, during hand-off into a congested cell, there may well be insufficient resource of the required type to admit the call/session into this cell. A number of existing processes can, and in various embodiments are, undertaken in accordance with the invention, for the MN and its various active sessions subject to sudden resource limitations. [0014] For example, the cell (Quality of Service) QoS control can try to rebalance the existing resources in the cell being entered to release sufficient resources for the new MN using the well-known techniques of pre-emption or borrowing, or the affected sessions of the MN can be dropped at the cell base station. [0015] In addition, according to this invention, if the basestation can maintain session or resource signaling independently of the media stream, and either the MN or the basestation can detect media resource shortages, then in the latter case the basestation can send a message to the MN indicting the media flows or resource requests that cannot be admitted at the new cell, or in the former case, the MN can detect this itself. Note that in either case this detection can also be done within a cell during a session when experiencing resource problems due to varying radio link conditions. The Receiving MN can then create a session signaling or resource message and send it to the other end of the affected sessions to inform them of the resource problem. Note that the basestation can alternatively send this message itself if it has end-to-end session knowledge of all participants and the session descriptions. Both ends are now aware of the problem and can then act on this knowledge to modify the session or resources. A number of alternatives are possible. [0016] The MN communications application, e.g., voice application, in the congested cell can signal the other end (e.g. the voice application on the other end of a call) to put the new or ongoing call on hold, advising the other end that it is due to a temporary resource problem in an reason code. Once the resources become available, communications sessions, e.g., calls on ‘resource hold’ get access to the available bandwidth. The call is then taken off-hold by the call's participants when the network signals that the resources are available and have been allocated to the node on hold. This is better than losing the call, as in existing systems, because the MN does not immediately redial (creating wasteful signaling) and instead the call will be automatically re-connected at the earliest opportunity. During the break both ends can, and in some embodiments do, exchange messages to be played, e.g., using reduced bandwidth signaling such as text messaging. In other embodiments the messages are signaled by the local BS to both ends and/or locally stored messages are played at the direction of the BS or MN. [0017] As an alternative to the above described resource shortage handling technique, the two application endpoints, e.g., MNs, can renegotiate the session description to be used during resource problems or this information can be exchanged when the original call was being set-up during session description negotiation. The session description would describe how to react to resource failure and can include: drop to text chat, drop to a lower codec fidelity or bit rate, play a message, etc. [0018] Alternatively, the reaction to insufficient resource could be to divert the session to a media recorder. In such an embodiment the unaffected application endpoint leaves a message which the affected user can listen to automatically when the resource becomes available and maybe then decide whether or not to call the unaffected user back. [0019] Alternatively, the call can, and in various embodiments is, redirected to a third person (e.g. a manager's secretary)/another team member, or to another terminal for the affected user such as a fixed phone near the MN's current location. The new call location could be communicated to the affected user via the still functional signaling plane. [0020] Alternatively, in various embodiments the payer for the call (normally the caller) or the affected user (additional payer for the local resource) is given the chance to increase the pre-emption level (resource priority) of the media flow, with an associated increase in ‘call’ cost, to enable the call to pre-empt an existing call and use its resource. In this case the message to the caller should include advice on the minimum required pre-emption level and the associated cost. In parallel, in some embodiments the caller on the identified call whose resources are to be removed (call to be pre-empted) is involved, e.g., notified of the impending interruption of service, so that an instantaneous ‘bidding war’, with a single bid per end-point, can be undertaken as to who gets the resource. Alternatively, such a bidding war can be avoided by a predetermined pre-emption ordering according to service level agreements (e.g., Gold users win over Silver users). [0021] In addition to the session/resource signaling responses it can be beneficial to put a rate-limit on the number of renegotiations in a fixed period to avoid responding too quickly to resource changes. In accordance with one feature of the invention this is achieved by adding hysterisis to the session or resource transition, and by setting a minimum reconfiguration time for each session. This increases in importance as the rate of cell change increases (small cells, fast MNs) to the extent that the signaling round trips are a significant fraction of the cell transition time. In effect, the slower the cell change, the more opportunity there is for session renegotiation whilst faster transition times increase the importance and utility of the temporary call hold feature of the present invention. [0022] Various features of the present invention such as a session holdmessage are particularly well suited to group communications sessions, e.g., multi-participant game communications sessions, where it is useful to convey temporary absence information to other group members. The signaled absence may be due, e.g., to being placed into a hold state due to resource shortages. In response to the absence message, the game application being executed by the group may take appropriate action to protect a players position in the game until such time as the player's bandwidth and connection are restored to normal. [0023] Numerous additional features, benefits, applications and embodiments of the present invention are described in the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWINGS [0024] [0024]FIG. 1 illustrates an exemplary communications system implemented in accordance with the present invention. [0025] [0025]FIG. 2 is a block diagram of an exemplary base station that may be used in the communications system of FIG. 1. [0026] [0026]FIG. 3 is a block diagram of an exemplary mobile node that may be used in the communications system of FIG. 1. [0027] [0027]FIG. 4 is a flow diagram illustrating the steps of an exemplary routine that can be used by a basestation to control session hold transitions for mobile nodes in accordance with the present invention. [0028] [0028]FIG. 5 is a flow diagram illustrating the steps of an exemplary routine that may be used to control resource re-allocation which can be used in conjunction with the method of FIG. 4. [0029] [0029]FIG. 6 is a flow diagram illustrating the steps of an exemplary routine that may be used by a basestation to control resources while allowing session hold transitions to be managed by the mobile nodes. [0030] [0030]FIG. 7 is a flow diagram illustrating the steps of an exemplary routine that may be used with the method of FIG. 6 to control resource re-allocation. [0031] [0031]FIG. 8 is a flow diagram illustrating the steps of an exemplary routine that may be used by a mobile node to control the transitioning into a session hold state in response to the occurrence of any one of a plurality of possible trigger events. [0032] [0032]FIG. 9 is a flow diagram illustrating the steps of an exemplary routine that may be used by a mobile node to the transitioning from a session hold state into a session on state in response to any one of a plurality of possible trigger events. DETAILED DESCRIPTION [0033] The present invention relates to communications session and resource management and, more particularly to methods and apparatus for enabling a mobile node to maintain a communications session despite a decrease in resources, e.g., temporary reduction or loss of bandwidth, used to support the communications session. [0034] Various aspects of the present invention are directed to novel methods, apparatus and data structures for enabling a mobile node to roam in a foreign network, with multiple basestation handoffs, while permitting the basestation and mobile node to collaborate to enable the mobile node and its session peers to adapt to resource shortages, either as a result of hand-offs or due to changing channel, e.g., radio channel, conditions. This is achieved by placing particular sessions into a hold state in accordance with the invention as necessitated by resource shortages. The following description is presented to enable one skilled in the art to make and use the invention, and is provided in the context of particular applications and their requirements. Various modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles set forth below may be applied to other embodiments and applications. Thus, the present invention is not intended to be limited to the embodiments shown and the inventor regards his invention as the following disclosed methods, apparatus and data structures and any other patentable subject matter and embodiments made obvious by the text of this application. [0035] Various terms used in the present application will now be explained so that they can be properly interpreted in the description which follows. [0036] Mobile Node: A host or router that can change its point of attachment from one network or sub-network to another. [0037] Mobile nodes may have some or all of the following attributes. A mobile node may change its location without changing its IP address; it may continue to communicate with other Internet nodes at any location using its (constant or persistent) IP address, assuming link-layer connectivity to a point of attachment is available. In various embodiments a mobile node is given a long-term (or persistent) (e.g., IP) address on a home network. This home address may be administered in the same way as a “permanent” IP address is provided to a stationary host. When away from its home network, a “care-of address” is associated with the mobile node and reflects the mobile node's current point of attachment. The mobile node normally uses its home address as the source address of all IP datagrams that it sends. [0038] Basestation: A node that serves as a network attachment point for one or more mobile nodes. [0039] Cell: The area of wireless coverage resulting from radio propagation and system limits that extends out from a radio antenna on a basestation. [0040] Session: A communication relationship that has a session description, which is negotiated and agreed between one or more session peers. The session description typically includes the time, duration and media types (voice/video codecs etc) for the session. [0041] Session Peer: A peer with which a network node, e.g., a mobile node, has a negotiated session. Session peers can be mobile or stationary. [0042] Link: A facility or medium over which nodes can communicate at the link layer. A link underlies the network layer. [0043] Link-Layer Address: An address used to identify an endpoint of some communication over a physical link. Typically, the Link-Layer address is an interface's Media Access Control (MAC) address. [0044] Node: A network element that serves as host or a forwarding device. A router is an example of one type of node. [0045] [0045]FIG. 1 illustrates an exemplary communications system 100 implemented in accordance with the methods and apparatus of the present invention. The system 100 includes first and second cells 10 , 10 ′ and a router 17 . The router 17 may be coupled to, e.g., the Internet. As shown, the cell 10 comprises a basestation 12 and a plurality of mobile nodes 14 , 16 . The base station 12 manages mobile nodes (MNs) 14 , 16 whilst in said cell, specifically providing bi-directional radio communications links 13 , 15 between the basestation and each mobile node. The basestation dynamically adjusts the bandwidth of the radio links 13 , 15 to share the bandwidth between all mobile nodes in the cell 10 as a function of the mobile nodes resource requirements and, in some embodiments, resource allocation priority. Mobile node resource requirements are known as a result of resource and/or session signaling from the mobile node 14 , 16 to the basestation 12 , and/or from mobile node specific configuration known to the basestation 12 independent of communications with the mobile nodes 14 , 16 . Cellular networks are typically comprised of a multitude of such cells. In regard to FIG. 1, the second cell 10 ′ is another cell which is the same as or similar to cell 10 . Elements of the second cell are denoted using a ′ to distinguish them from like numbered elements of the first cell. For example the base station in the second cell 10 ′ is indicated using reference number 12 ′. [0046] In the FIG. 1 example, mobile node 1 , 14 appears in both the first and second cells. While this may occur in cases where cells overlap, in the FIG. 1 example, the presence of the first mobile node 14 in the second cell 10 ′ occurs as the result of movement of the mobile node 14 from the first cell 10 to the second cell 10 ′ as represented by arrow 20 . Thus, in the FIG. 1 example, mobile node 14 is present in second cell 10 ′ at a point in time subsequent to the time it is in the first cell 10 . [0047] The base stations 12 , 12 ′, of the first and second cells 10 , 10 ′, are interconnected by network nodes such as IP router 17 which are coupled to the base stations by communications links. In the FIG. 1 example, fixed communication links 18 , 19 interconnect the router 17 and the basestation 12 , 12 ′. This allows the base stations 12 , 12 ′, and mobile nodes connected thereto, to interact with one another by way of communications links 18 , 19 and router 17 . [0048] Communications resources, e.g., bandwidth, available to a mobile node 14 may vary as a function of a variety of factors including demands of other nodes in a cell 10 , 10 ′, resource demands of nodes entering and/or leaving the cell, and the quality of the radio link with the base station 12 or 12 ′ servicing the mobile node. [0049] When a mobile node (MN) 14 moves geographically, the radio propagation between it and nearby basestations (BS) 12 , 12 ′ varies. As a result of changes in radio communication due to movement, when moving into the second cell 10 ′ from the first cell 10 , the preferred BS changes from 12 to 12 ′. In order to allow communication through the preferred base station a hand-off will occur from the current base station to the new preferred base station. Thus, when a mobile node moves from the first cell 10 to the second cell 10 ′ a handoff will occur. As a result the mobile node, e.g., node 14 , entering the second cell 10 ′ will begin being served by BS 12 ′. This hand-off causes the resource and session information, sometime called “state” or “state information”, known in BS 12 to be transferred to BS 12 ′. As a result of the handoff, the resource demands in cell 10 are reduced while the demand for resources in cell 10 ′ increases due to the movement of the MN into the cell 10 ′. [0050] As the MN 14 moves within the new cell 10 ′ the maximum potential radio link capacity in either direction between MN 14 and BS 12 ′ will vary as a function of the mobile node's, 14 , distance from the base station 12 ′. Changes in the maximum potential radio link capacity can affect the resources available to the MN 14 . Hand-offs for other MNs, e.g., 16 , into the same cell 10 ′ can place additional demands on the resources in the cell 10 ′. The basestation 12 ′ is used to manage resources, and resource allocation requests, as mismatches occur between the total available resources in cell 10 ′ and the sum of the resource demands from MNs in the cell 10 ′. This management may result in the basestation requiring a node with allocated resources to discontinue, e.g., relinquish, some of the utilized resources before the mobile node completes an ongoing communications session. While in known systems this would normally result in a communication session being dropped, in accordance with the present invention a communications session may be placed into a hold state as will be discussed further below. [0051] [0051]FIG. 2 is a block diagram of an exemplary BS 12 that may be used in the communications system of FIG. 1 to permit a roaming mobile node to effectively manage sessions during resource shortages. As shown, the exemplary BS 12 includes a receiver circuit 202 , transmitter circuit 204 , processor 206 , memory 210 and a network interface 208 coupled together by a bus 207 . The receiver circuit 202 is coupled to an antenna 203 for receiving signals from mobile nodes. The transmitter circuit 204 is coupled to a transmitter antenna 205 which can be used to broadcast signals to mobile nodes. The network interface 208 is used to couple the base station 12 to one or more network elements, e.g., router 17 and/or the Internet. In this manner, the base station 12 can serve as a communications element between mobile nodes serviced by the base station 12 and other network elements. [0052] Operation of the base station 12 is controlled by the processor 206 under direction of one or more routines stored in the memory 210 . Memory 210 includes communications routines 223 , data 220 , session management routine 222 , resource reallocation routine 225 , session signaling subroutine 224 , resource signaling subroutine 218 , messages 215 , and active user information 212 . Communications routines 223 , include various communications applications which may be used to provide particular services, e.g., IP telephony services or interactive gaming, to one or more mobile node users. Data 220 includes data to be transmitted to, or received from, one or more mobile nodes. Data 220 may include, e.g., voice data, E-mail messages, video images, game data, etc. Session management routine 222 is to oversee various communications sessions which may be supported by the base station 12 at any given time. Each mobile node in the cell serviced by the base station 12 may have any number of active communications sessions going on at any given time. Session management routine 222 is responsible, at least partially, for resolving conflicting resource requests that may be made by the various mobile nodes in a cell. Resource reallocation routine 225 , is used by the base station 12 to address resource allocation issues, specifically when there are insufficient resources available to satisfy the resource requests made by the various mobile nodes being serviced by the base station 12 . Session signaling subroutine 224 is responsible for controlling session signaling, e.g., SIP signaling, which is supported by the base station 12 . Resource signaling subroutine 218 is responsible for controlling resource signaling, e.g., RSVP signaling, which is supported by the base station 12 . Messages 215 may be stored messages sent to notify communications session participants of the temporary absence of a communications session participant and/or to notify the session participants that a communications session participant has been put on hold. Messages 215 may also be stored messages sent to notify communications session participants of the temporary absence or return of a session resource. Active user information 212 includes information for each active user and/or mobile node serviced by the base station 12 . For each mobile node and/or user it includes a set of state information 213 , 213 ′. The state information 213 , 213 ′ includes, e.g., a list of communications sessions in which the node and/or user are participating, the communications resources used by each listed communications session, and whether the session and/or resource is in an active, e.g., session on state, or a hold state as supported in accordance with the present invention. [0053] In accordance with the present invention, resource shortages are handled by base station 12 under the direction of session management and/or resource allocation routines 222 , 225 potentially in conjunction with the MN 14 , based on the relative importance of user sessions known from user data or via negotiation with MNs. Various exemplary session management and resource allocation routines which may be used as the base station routines 222 , 225 will be discussed below. [0054] [0054]FIG. 3 is a block diagram of an exemplary mobile node (MN) 14 that may be used as one of the mobile nodes 14 , 16 of the communications system shown in FIG. 1 along with the the exemplary base station (BS) of FIG. 2. When used in combination with the base station of FIG. 2 in accordance with the present invention, mobile node 14 can support the maintenance of communications sessions during resource shortages, e.g., in a session hold state. [0055] The exemplary MN 14 includes a receiver circuit 302 , transmitter circuit 304 , processor 306 , memory 310 coupled together by a bus 307 . The receiver circuit 302 is coupled to an antenna 303 for receiving signals from one or more basestations 12 , 12 ′. The transmitter circuit 304 is coupled to a transmitter antenna 305 which can be used to broadcast signals to basestations 12 , 12 ′. The mobile node 14 can interact with mobile nodes and other network elements by establishing communications sessions through a base station 12 , 12 ′. [0056] Operation of the mobile node 14 is controlled by the processor 306 under direction of one or more routines stored in the memory 310 . Memory 310 includes communications routines 323 , data 320 , mobile node processing routine 322 , resource reallocation routine 325 , session signaling subroutine 324 , resource signaling subroutine 318 , messages 315 , and information 312 . Communications routines 323 , include various communications applications which may be used to provide particular services, e.g., IP telephony, E-mail, video, games, etc. to a user of the mobile node 14 . Data 320 includes data to be transmitted to, or received from a base station 12 , 12 ′. Data 320 may include, e.g., voice data, E-mail messages, video images, game data, etc. Mobile node processing routine 322 is used to oversee various communications sessions which may be supported by the base station 12 at any given time, to detect and to respond to various trigger events. In response to a trigger event, such as the receiving a particular message or detecting a resource shortage, the processing routine 322 can control the mobile node to transition a communications session between a session on state and a session hold state. It can also control a communications session to transition from a session hold state to a session on state, e.g., when an event such as the allocation of resources needed to restore a communications session to an on state is detected. Each mobile node 14 may have any number of active communications sessions going on at any given time. Resource reallocation routine 325 is used, in some embodiments, by mobile node 14 to address resource allocation issues when there are insufficient resources available to satisfy the resource requirements of the various communication sessions the mobile node 14 is involved in. Session signaling subroutine 324 is responsible for controlling session signaling, e.g., SIP signaling, which is supported by the mobile node 14 . Resource signaling subroutine 318 is responsible for controlling resource signaling, e.g., SIP preconditions or RSVP signaling, which is supported by the mobile node 14 . Messages 315 may be stored messages sent to notify communications session participants of the impending temporary absence of the mobile node from an on going communications session. This may include indicating that the mobile node 14 is being put on hold for a particular communications session. Information 312 includes information about the ongoing communications sessions supported by the device. It may list such sessions on a per user basis where the device can be used by multiple users. For each communications session, the information 312 includes resource and status information, e.g., the communications used and/or required for the session and whether the communications session is in a session on or a session hold state. An exemplary mobile node processing routine which may be used as the routine 322 will be discussed in detail below. [0057] [0057]FIG. 4 is a flow diagram illustrating the steps of an exemplary base station session management routine 400 that can be used as the session management routine 222 of exemplary basestation 12 . The routine 400 starts in step 402 when the routine is executed by the base station's processor 206 , e.g., after the base station 12 is powered up. As indicated by input block 405 , the main acts of the method 400 are performed in response to trigger events 405 , which correspond to the receipt of messages or the detection of particular conditions. Trigger events are detected in step 410 and cause processing associated with the trigger event to proceed to step 415 . Monitoring is performed in step 410 on a continuous basis with each detected trigger event resulting in separate processing, e.g., by steps 415 etc sequence. Trigger events 405 include, for example, session request messages and session release messages. Such messages may be generated either by MNs 14 , 16 in the cell or by the BS 12 in response to session state transitions within the BS 12 due to hand-off activity such as existing sessions leaving or arriving into the cell 10 with MNs 14 . In step 410 , a monitoring process looks for changes in the set of sessions employed by the plurality of MNs in the cell, along with the resources associated with those sessions. In response to detection of a session message, operation proceeds to step 415 . In step 415 , a test is conducted to determine if additional resources have been requested or existing resources released, e.g., whether a session request or release message was received. [0058] If additional resources have been requested, operation proceeds from step 415 to step 420 . In step 420 the total amount of resources, including the new request, required for ongoing sessions at the BS 12 is compared to the total resources available in the cell 10 , to see if the new resource request can be granted in step 420 . This can simply be a comparison between the amount of free resource in the cell and the size in terms of resources of the additional session request. Note that a session request includes a change in the session description of an existing session that increases the required resources for that session. Thus, in step 420 the BS 12 decides whether or not there are sufficient resources, e.g., bandwidth, available to satisfy the request. If sufficient resources are available to satisfy the required operation proceeds to step 425 wherein the BS 12 grants the requested resource(s) to the requesting session. Step 425 leads to block 428 wherein the BS 12 allows a new session to be conducted using the granted resource or modifies an existing session to employ the new granted resources for the communication session. [0059] If, in step 420 the BS 12 determines that there are insufficient resources available to satisfy the received resource request, operation proceeds from step 420 to step 430 . In step 430 a comparison between the priority of the requesting session is made to the priority of existing sessions to which the requested resource has been allocated. If in step 430 it is determined that the requesting session does not have higher priority, than an existing session which is using the requested resource, operation proceeds to step 439 . In step 439 , the requesting session is marked as a session hold candidate. Operation proceeds from step 439 to step 440 . [0060] If in step 430 it was determined that the requesting session has a higher priority than a session to which the requested resource is already allocated, the resource will be reassigned to the requesting session. As part of the resource reallocation process, in step 435 , processing goes to the start of a resource re-allocation routine, e.g., the exemplary resource re-allocation routine 500 shown in FIG. 5 (XX 500 was not marked in FIG. 5 so I have updated). The resource re-allocation routine determines from which ongoing session the requested resource is to be reallocated. The existing session from which the resource is to be taken is identified and marked by the resource re-allocation routine as a session hold candidate. Once processing by the re-allocation routine is completed, i.e., a session is identified and marked as a session hold candidate, operation returns to the main processing routine 400 and continues from step 440 . [0061] In step 440 a test is made against the user/device/session data 213 , to see if the device and session corresponding to the session marked as a hold candidate, supports a session hold state, whereby the marked session and the session participants can be put on hold temporarily until resources become available. If the device or session participants do not support a hold state, meaning the session hold candidate will have to be terminated to refuse the session request, or to permit the reallocation of requested resources, then operation proceeds from step 440 to step 445 where a signal is sent to the participants in the session hold candidate cancelling the session and the corresponding resource request (I have modified the text in 445 accordingly). Operation proceeds from step 445 to Stop step 470 wherein processing in response to the received session request is halted. [0062] Referring once again to step 440 , if it was determined that the device and session corresponding to the session hold candidate did in fact support a session hold state, operation would proceed to step 428 via steps 455 and steps 460 . In step 455 the BS 12 signals the session peers to put the session hold candidate into session hold, and optionally includes a reason code to explain why this is happening, and a hold action instruction to be undertaken by the session software at the session peers during the hold period. Examples of such actions include the playing a tone, displaying a message to the screen, or in an interactive game invoking game play local to the node (game player and gaming server) that does not disadvantage the session peers in session hold compared to other session at the game server in the same game. Then, in step 460 , the held session is placed into a hold queue 219 with, e.g., session priority and time stamp information. Thus, the held session is put into a queue of held sessions at that BS 12 with a priority and locally generated timestamp. If the session request is from a held session that just transferred into this cell as part of a hand-off, then the priority and timestamp of that held session will not be updated at block 460 , but will be installed as is into the hold queue of this cell. This is so that handed off sessions do not lose their global place in the session hold queue at a particular cell, during a cell change, and requires a degree of time synchronization between basestations as is common in exemplary implementations. Accordingly, as the mobile node 14 passes from cell 10 to cell 10 ′ the hold queue 119 information corresponding to sessions being maintained by the mobile node 14 is passed along with other state information from BS 10 to BS 10 ′. As a result, the hold queue 219 may include hold information transferred from another cell as part of a handoff operation. [0063] Operation proceeds from step 460 to step 428 wherein the BS 12 allows the communication session to which the resources were allocated to be conducted using the allocated resources. [0064] The request message processing branch of the routine 400 has been described in detail. Processing of resource release messages will now be discussed. If in step 415 , it is determined that a resource release message was received, operation proceeds from step 415 to step 469 . The resource release message may be a result of a MN 14 and its sessions leaving the cell, the cessation or renegotiation for lower resources for a particular active session, or new resources becoming available in the cell 10 for other reasons such as capacity increases. In step 469 , a check is made to see if any sessions are presently in session hold and hence awaiting resources. If no sessions are in hold then processing of the received release message stops in stop step 465 but monitoring for resource messages at block 410 is allowed to continue. If in step 469 it is determined that there are sessions in hold then operation proceeds to step 470 . In step 470 , the available resources are allocated to held sessions in the queue, with the highest priority sessions being served first, and the length of time in session hold, determined from the global timestamp, being used to order allocations within the same priority level. Note that if the resources are insufficient for higher priority session to be taken out of session hold then a lower priority session with smaller resource requirements can still be allocated the resource to ensure maximum use of resources is made. Other well-known algorithms are also applicable for ordering the sessions in the hold queue, and for holding back partial resources for high priority sessions with large resource requirements, in preference to allocating such resources to lower priority sessions [0065] From allocation step 470 , operation proceeds to step 475 . In step 475 , a determination is made as to whether the released resources were allocated to a session in hold state. If the freed resources were insufficient to enable any session to be brought out of session hold, then the released resources are simply left spare at the input to step 475 and operation will proceed to step 485 . In step 485 the unused resources are made available for use in servicing future resource requests, or borrowed by elastic applications with resources allocated that are less than the peak resources possible for that application, or cam be consumed by best effort traffic for which no resource signaling is conducted. In contrast if in step 470 a session in hold has been granted sufficient resources then operation would proceed via step 475 to step 480 . In step 480 the basestation 12 signals the session peers to transition the session to which the resources were allocated from hold into an active state and then allows the session to use those resources in step 428 for purposes of a communication session. [0066] The exemplary resource re-allocation routine 500 , shown in FIG. 5, may be used as the BS resource reallocation routine 225 shown in FIG. 2. It may be used in conjunction with routine 400 . The resource re-allocation routine starts in step 502 , e.g., in response to yes at block 430 and activation of step 435 of the routine 400 in FIG. 4. [0067] Resource reallocation routine 500 is used to redistribute resources as a function of a priority level associated with each session that is using or requesting resources. In accordance with the invention, before being denied the use of its resources needed for an identified communication session of lower priority, an associated identified user and/or device may be presented with the opportunity to upgrade the priority associated with that particular identified communications session. [0068] The routine 500 proceeds from start step 502 to step 505 where an existing session, having the requested resources, in the cell 10 with lowest priority is identified by the BS 12 . This session is henceforth called the identified session. In step 510 a test on the identified session data is undertaken to see if the mobile node 14 in the cell 10 corresponding to the identified session, i.e., is a member of the identified session, supports a dynamic priority upgrade option. In accordance with the invention, the dynamic priority upgrade option allows users corresponding to an identified session to dynamically increase the session's priority in an attempt to avoid resource reallocation to the requesting session, and having the identified session dropped or put on hold. The dynamic priority upgrade option may be presented to the mobile node user as part of a bidding war for the resource which occurs with other sessions whose individual resource is sufficient to satisfy the resource request. Note that whilst the exemplary routine in FIGS. 4 and 5 covers the case of a one to one comparison between sessions, it will be obvious to someone skilled in the art that a suitably important requesting session with large resource requirements could result in resources being taken from more than one existing session of lower priority, resulting in a multitude of identified sessions. The requesting session may be included in the bidding processes and considered among the devices from which the requested resource may be taken. In this manner, if the requesting session's priority is exceed as the result of bidding by all the active devices to which the requested resource has already been allocated, the requesting session may be selected as the session to be put into a hold state. In step 510 , if the identified session does not support dynamic priority option then operation proceeds directly to step 569 which will be discussed below. [0069] If, in step 510 , it is determined that the mobile node associated with the identified session supports the dynamic priority upgrade option, then a test at step 520 is executed to ensure that the number of upgrades in this pass of the routine has not exceeded some limit. If a limit has been exceeded then the routine settles on the present identified session with the lowest priority and proceeds to step 580 . If the limit has not been exceeded then another upgrade is allowed and a priority upgrade message is sent to the present identified session user in the cell, e.g., the BS 12 sends the mobile node 14 associated with the identified session a signal indicating that the mobile node should present the user of the mobile node 14 , with an upgrade option signal. This may be, e.g., a visible indicator, e.g., a light or text message, presenting the user of the mobile node 14 with a chance to select an upgrade in priority. Thus, the upgrade option message can be presented to the user on a display which is part of the MN 14 . Alternatively, the upgrade option signal can be processed by or interact with policy state/user agent processes, e.g., routines, in the MN 14 that automatically control such bidding for priority upgrades, e.g., in accordance with preprogrammed user selections. Such automated control may be based, at least in part, on the increase in priority required to maintain the session and the associated financial cost of increasing session priority to that level at the time the upgrade option signal is received. [0070] In response to the upgrade option signal a mobile node 14 responds to the BS 12 with a signal indicating whether or not the upgrade has been selected, e.g., manually by the user of the mobile node 14 or automatically by the MN 14 . The response message is received by the BS 12 from the MN 14 . The response message is tested in step 540 . If the upgrade option has been refused then the identified session and user is will be left unchanged and processing will proceed from step 540 to step 569 . However, if the upgrade option has been accepted then processing passes from step 540 to step 550 where the user session state 212 is updated with the new priority for the session. Then, in step 560 the number of upgrades in this pass of the routine is incremented for the identified user, and for all users so that a limit on the number of bids per user, the signaling rate and latency can be applied to the process of selecting the final identified session. The routine 500 finally passes back to step 505 where the lowest priority session with sufficient resource for the requesting session user is once again identified, taking into consideration the upgrade in priority, for the next loop of the routine. Eventually the processing will proceed to step 569 with a final identified session. [0071] In step 569 session resources are reallocated from the identified device to the requesting device. In this manner, resource reallocation occurs asynchronously from session management, e.g., placing the session from which the resources were reallocated into a hold state or terminating the session. This is consistent with the normal case of session signaling for a specific MN lagging cell resource changes, e.g., unpredictable changes due to radio environment, changes in number of active sessions for the MNs already in a cell, changes in number of active sessions as a result of hand-off of MNs. [0072] From step 569 , operation proceeds to step 570 wherein the BS 12 transmits a session signal to the requesting MN 14 and its session peers granting the requested session resources. Then, in step 580 , the identified session is marked as a session hold candidate. From step 580 processing returns to the routine which called the resource reallocation routine 500 via return step 590 . In the case of a go to operation invoked by step 435 of FIG. 4, operation will be returned to step 440 of routine 400 which then used the session marked as a session hold candidate as part of further processing. [0073] Note that an alternative exemplary method of signaling and receiving bids is to broadcast the requesting session priority out to all session users in the cell and to then collect bids from all users that wish to make a bid that will increase their present session priority, from a level that is lower than the priority of the requesting user. The basestation then selects the lowest resultant session as a session hold candidate. This minimizes the bandwidth and latency of the bidding process. [0074] [0074]FIG. 6 shows a flowchart for an alternative basestation routine 600 , that employs an alternative a re-allocation routine shown in the flowchart of FIG. 7. In the FIG. 6 embodiment, the basestation 12 identifies a session and corresponding mobile device from which the requested resources are to be reallocated, in the case where there are insufficient resources, to satisfy a request having a higher priority than the session from which the resources are to be reallocated. In the FIG. 6 embodiment the base station notifies the corresponding mobile node 14 , from which the resources are to be taken, that the resources are unavailable and the mobile node 14 is given the opportunity to signal that the session using the resource is to be placed into a hold state, the session resources reduced down (not discussed further as this can be treated like a new session to the resource system), or terminated. In such an implementation, the basestation 12 does not have to keep track of a mobile node's ability to support a session hold state leaving the decision to drop a session or place a session into a hold state in response to resource shortages. In such an implementation, the dropping or placing of a session into a hold state is under the control of the mobile node 14 , which serves as the end node for the session subject to the resource shortage. [0075] Many of the steps of the FIG. 6 basestation routine 600 are the same as the steps of the previously described routine 400 shown in FIG. 4. For the purposes of brevity such steps are identified in FIG. 6 using the same reference numbers as used in FIG. 4. Such steps will not be described again here. The steps of the basestation routine 600 which differ from the routine 400 are identified using reference numbers in the 600 's range. The routine 600 starts at step 602 but, in contrast to the FIG. 4 implementation, the basestation 12 is interested in resource request/release messages that serve as trigger events rather than session release/request messages because in the FIG. 6 embodiment session management is left primarily to the session users, e.g., users of nodes 14 . The resource messages 605 might come directly from user resource messages, e.g., RSVP messages, or can instead be derived by the BS 12 from received session messages, e.g., SIP messages. In step 610 the resource messages 605 are monitored. For each received resource message processing proceeds to step 615 . In step 615 messages that affect present resource allocations are tested to see if they are a request or a release message. [0076] If the message is a resource request then steps 420 , 425 , 428 , and 430 are performed as in the case of the FIG. 4 embodiment. Note that steps 425 and 430 use information identifying the session associated with a resource request and related priority information. This information is kept in the basestation 12 user session information 222 and is available for use on an as needed basis. With this information, in step 430 the priority of the resource request can be determined. If there is no existing session with the requested resources that has a lower priority, operation will proceed from step 430 to step 640 via step 639 . In step 639 the requesting device is marked as an identified device for subsequent processing and the requested resource is marked as unavailable. [0077] If an existing session with lower priority exists, and is using the requested resources, operation will proceed from step 430 to step 640 via step 635 . Step 635 is a GOTO step which involves a jump to the alternate resource re-allocation routine 700 shown in FIG. 7. [0078] [0078]FIG. 7 shows the alternate resource re-allocation routine with the modified steps being identified with numbers in the 700 's. The routine 700 is similar to the routine 500 with the exception of steps 730 , 770 and 780 . As in the case of the routine 500 , the routine 700 seeks to determine, e.g., identify, a session and corresponding device whose resources can be given to the requesting session, whilst giving the session user at a MN 14 in the cell 10 an option to defend its resources by upgrading the priority of its session and hence the priority of its resource requests in the basestation 12 . The differences in the FIGS. 5 and 7 embodiments are generally restricted to the signaling plane. In the FIG. 7 embodiment a resource priority upgrade option message, rather than a session message is sent to the local MN in step 730 . In addition, in step 770 , a resource grant signal is sent to the device associated with a resource request as opposed to a session resource grant signal being transmitted. Finally, at block 780 it is the resource rather than the session that is marked as unavailable for the identified communications session, and it is therefore the resource request, i.e., the previously granted resource request that was canceled as a result of resource reallocation, that is therefore a candidate to be queued at the BS 12 . In step 590 the routine 700 returns to FIG. 6 where step 640 is executed next. [0079] As a result of processing in either step 635 or step 639 , an identified resource has been marked as unavailable and hence at block 640 a resource unavailable message, with a resource id identifying the specific resource and its relationship to a session at MN 14 , is sent to the identified device, e.g., MN 14 , in the cell 10 . This will cause the MN 14 to react to the resource change by noting the loss of resource, determining the associated session, and then modifying the associated session using session signaling, e.g., SIP. In step 645 the fact that a resource has become unavailable for a session, e.g., the identified session, as a result of a denial of the resource request or reallocation of the resource, is recorded in the hold queue 219 maintained in the basestation's memory 210 . This may be done by adding an appropriate resource request to the hold queue 219 with, e.g., a designated priority, a timestamp, the resource id and the associated session identifier. As in the previous example, the removal of resources from a session may occur asynchronously from changes in the session state. Thus, the loss of resources due2 to resource re-allocation will normally occur before the session state is placed into a hold state or the corresponding session from which the resources were take is terminated. A mobile node discovering the loss of resources may signal to the BS 12 , in accordance with the invention, whether the session from which the resources were taken should be placed in a hold state or terminated. With the placing of the resource request in the hold queue 219 , the associated session in the user session state 213 is marked as short of resources and will be converted in to a session hold state or terminated upon the MN 14 indicating the desired treatment. Following placement of the information in the hold queue 219 , processing the resource request message stops in step 450 . However, monitoring for additional resource messages continues on an ongoing basis in step 610 . [0080] If a resource release message is detected in step 610 , instead of a resource request message, processing proceeds from step 610 to step 460 by way of step 615 . As in the FIG. 4 example, in step 460 the BS 12 checks to see if there are any sessions on hold as a result of denial of previous resource requests or the reallocation of resources from existing communications sessions. This is accomplished by checking the contents of hold queue 219 . Steps 465 , 470 and 475 are performed, with step 475 establishing if the freed resources are suitable, e.g., sufficient, for a current session (resource) on hold. If they are not, then the released resources are added to a free resource stack, which includes resources which can be utilized by existing and potential future sessions. If the resources are suitable, e.g., sufficient, for a session on hold, then at step 475 operation proceeds to step 680 where a resource available message is sent to the MN 14 that is a local member of the session to which the freed resources are being allocated. Processing then proceeds to step 428 where the communications session to which resources were allocated, can use the allocated resources for a communications session, e.g., allowing a communication session previously on hold to transition to an on state. Note that the resource available, e.g., resource grant, message could be refused by the MN 14 with a resource or session message due to it no longer wishing to pursue a session, e.g., because it choose to terminate a session as opposed to place it on hold. [0081] The method shown in FIG. 6, enables the MN 14 in the cell 10 where the BS routine 600 is executed, to be informed of the available/unavailable resources for the user sessions at the mobiles 14 , 16 in the cell 10 , and hence allow the MN 14 or 16 to locally react by sending session signals, e.g., SIP signals, in response to the resource changes. The MN 14 can then either change the session resource requirements (including putting the affected session on hold), borrow resources from another session that that MN 14 is involved in, or cancel the affected session altogether. In accordance with the present invention, the MN 14 issues session signals indicating its decision on how to handle an affected session to the peers and/or base station 12 . This mobile node based approach to session management is an alternative to the base station approach to session management described with regard to FIGS. 4 and 5 wherein session signals used to control the termination or placing of sessions into a hold state are generated and transmitted by the basestation 12 . The basestation based session management method shown in FIGS. 4 and 5 minimizes the amount of signaling between the MN 14 and its peers, but increases the amount of session knowledge needed at the basestation and ultimately removes or reduces the power from the MN 14 to manage its own sessions as it sees fit. This model is appropriate for simple, dumb mobile nodes 14 running simple sessions, or sessions that the basestation 12 will ultimately have to control. The methods illustrated in FIGS. 6 and 7 in contrast to the FIGS. 4 and 5 methods, minimize the basestation session knowledge requirements but increases the amount of signaling which is performed by the MNs 14 , 16 . However, the benefit of such signaling is that MN 14 is in control of what it wishes for its communications sessions. This is more like the Internet model which assumes intelligent hosts, and is appropriate in applications where the basestation 12 can yield session control to the mobile nodes 14 , 16 . [0082] Having described the basestation processing for resource and session on hold management we now move on to the mobile node view of these interactions, which are described in the flowcharts shown in FIGS. 8 and 9. [0083] For a mobile node 14 to be able to roam freely, it should be able to deal with basestations 12 , which implement either the method of FIGS. 4 and 5 or the alternative method of FIGS. 7 and 8. This has the advantage of allowing a mobile node 14 to interact with multiple basestations 12 , 12 ′ as it moves around or to deal with cases where a single session involves base stations 12 , 12 ′ which support different techniques, e.g., the FIG. 4 or FIG. 6 techniques of handling session and resource control. [0084] Exemplary mobile node processing routine 800 , comprising first and second parts, 800 a and 800 b , is shown in FIGS. 8 and 9. The routine 800 may be used as the mobile node processing routine 322 of the mobile node 14 . [0085] [0085]FIG. 8 illustrates a first portion 800 a of the mobile node processing routine 800 . Portion 800 a handles the processing of trigger events that have the potential to cause a transition of a MN communications session from an “on” state into a session “hold” state. FIG. 9 illustrates the second portion 800 b of the mobile node processing routine 800 . The second portion 800 b handles the processing of trigger events that have the potential of allowing a transition of a MN session from a “hold” state to a “session on” state. A start step 802 of routine 800 is divided into parts 802 a shown in FIG. 8 and start step 802 b in FIG. 9 for purposes of illustration. However, both parts 802 a and 802 b represent part of the same step 802 which involves execution of the routine 800 by the mobile node 14 . Similarly trigger event detection step 810 is shown as two separate parts 810 a and 810 b but may be part of a single trigger event detection step. The processing performed following step 810 will depend on the type of trigger event that is detected. For purposes of illustration, FIG. 8 deals with trigger events that may cause a mobile node communications session to transition into a hold state while FIG. 9 deals with trigger events that may cause a mobile node communications session to transition from a hold state to an on state. [0086] Referring to FIG. 8, the MN processing commences at block 800 a , in step 810 a any one of four types of trigger events may be detected. The first trigger event is an upgrade option message that could either be a session or resource message, and which was issued by a BS 12 while executing a resource reallocation routine, e.g., as part of step 530 , 730 . This causes processing to pass to step 815 where the upgrade option is presented to a user of the MN 14 or to a user agent process, e.g., automated MN routine. Then in step 820 , in accordance with the present invention, a user/user agent upgrade decision is received and in step 825 the received decision is returned, e.g., transmitted, to the basestation 12 as a session or resource upgrade reply message. In stop step 827 processing corresponding to the detected upgrade option message is halted however, step 810 continues to monitor for trigger events which may trigger additional processing by the routine 800 . [0087] The second type of trigger event that may be detected in step 810 a is a session hold signal received from a basestation 12 or from a session peer, e.g., MN 14 or 16 , that has itself decided to put a session on hold. This causes the processing to proceed from step 810 a to step 880 where the session application implements the session hold action for that session which is either negotiated during session set-up, configured in the application or signaled, e.g., specified, in the detected session hold message. Processing then proceeds to step 885 where the MN 14 waits for a resource change for the session that has been put on hold. Monitoring in step 810 a continues in an attempt to detect additional trigger events thought the processing of a hold signal. [0088] The third trigger event that maybe detected in step 810 a is an internal resource unavailable message from a MN networking stack included in the MN 14 that indicates that the MN 14 is not getting sufficient resources for the MN's active sessions and hence below the resources previously promised by the basestation 12 . This trigger therefore implies a resource shortage (unavailability) at the basestation 12 . Detection of an explicit resource unavailable message received by the MN 14 from a basestation 12 will also result in operation proceeding from step 810 a to step 830 . This represents the fourth and final trigger event that may be detected in step 810 a . Hence either of the last two triggers will cause processing to pass from block 810 a to block 830 . The MN communication sessions affected by the detected trigger are determined, e.g., identified, in step 830 . Operation then proceeds to step 835 . [0089] In step 835 , the MN session state information 312 is interrogated to see if the session signaling, the session peers and the application associated with the affected session(s), identified in step 830 , support session hold. If session hold is not supported then each affected session is cleared using session signaling with peers 14 , 16 and the basestation 12 , as appropriate to the local basestation 12 processing, e.g., in accordance with the method of FIGS. 6 and 7. Note that the basestation 12 will see the session signaling messages and deduce that the affected session has been cancelled and that the associated resources have been released. Processing proceeds from step 890 to step 895 wherein processing of the detected trigger event stops. [0090] If, however, in step 835 the it is determined that the affected application does support session hold then operation proceeds from step 835 to step 840 . In step 840 the MN 14 determines whether the affected session is a unicast or a multicast session. If it is a multicast session in step 850 a multicast session hold message is sent to the multicast session peers. However, if the affected session is a unicast session, operation proceeds instead to step 860 wherein one or more unicast session hold messages are sent to the unicast session peers. Note that a basestation 12 that initiates session hold messages should also be able to send both multicast and unicast session hold messages. The session hold reason in either case (unicast or multicast) should contain a reason code as well as an action code, so that each peer knows why the session is to go into session hold. This enables the peer to decide if it wishes to stay in the session waiting for resource to return, or to save resources at its basestation 12 by canceling its leg of the session with the MN 12 . Whether a multicast or unicast session hold message is sent, a response will be received back by the MN 14 indicating that the session hold was either accepted or rejected. If accepted then at step 880 the application and the application peers put the session into hold and implement a session hold action, e.g., an action communicated in the hold message, such as playing a tone. Then, operation proceeds to step 885 , wherein the MN 14 and its peers again wait for a resource change so that the session now in the hold state can be restored to an active, e.g., “on” state. [0091] Note that while at step 835 the test is simply shown as whether the affected MN application supports session hold, the MN 14 could still choose to cancel an affected session rather than go into hold. This would cause the MN 14 to move to step 890 , cancel the session. Monitoring for trigger events would continue in step 810 a despite cancellation of the affected session. Note also that one session end-point puts the session into session hold and out of session on, with a reason code to indicate the reason for this such as resource unavailable, and all peers implement the action code associated with that transition and reason. [0092] Referring to FIG. 9, the MN processing commences at block 800 b , where in step 810 b any one of three types of trigger events may be detected. The first trigger event that may be detected in step 810 b is a session on signal (session out of hold/active) received from the basestation or a session peer. This causes the processing to proceed from step 810 b to step 975 where the MN 14 sends a response accepting the session on message and associated reason/action, to the issuing peer/BS, and then passes the action code to step 980 , where the application implements the session on action. This could be, for example, to stop playing the tone and start sending/receiving media in the session. The processing then moves to the stop at step 995 . Processing of other trigger events continues at step 810 b throughout the processing of each detected trigger event and despite stop step 995 being encountered. [0093] The next potential trigger that may be detected in step 810 b is a resource available message, from the MN 14 itself, and generated from its internal networking stack having detected that additional resources are now available. An equivalent trigger is the resource available message received from the local basestation which also signals the return of resources to the MN 14 . In either case, operation proceeds from step 810 b to step 920 where the affected session is determined either as a result of an explicit resource id in either received or detected resource message, which has a known local mapping to sessions, or as a result of the MN 14 prioritizing its sessions access to shared resources, using the session priority and timestamp state information that was similarly employed by the basestation in FIGS. 4, 5, 6 and 7 . At step 930 , the selected session is checked to ensure it is still in hold and if it is not, and has already been cancelled, then the processing moves to step 990 where the selected session maybe restarted before we move to step 995 . If instead, the session is held at step 930 then we again check to determine if it is a multicast or unicast session in step 940 , so that the MN 14 can send the correct type of session on message to its session peers, with reason and action code, using step 950 or step 960 . At step 970 the MN 14 receives the session hold response and passes the action code to the application so that at step 980 the application implements the session on action, before processing of the particular detected event stops in step 995 . Therefore one session end-point puts the session out of session hold and into session on, with a reason code to indicate the reason for this such as resource now available, and all peers implement the action code associated with that transition and reason. [0094] In summary, the combination of resource and session messages, plus the relationship between those messages and the associated session state being maintained in the basestations 12 , 12 ′ and the MNs 14 , 16 , enables the basestations 12 , 12 ′ and the MNs 14 , 16 to collaborate to enable sessions to be put into and out of session hold in the presence of resource shortages. The type of application processing whilst in session hold is dependent on both local application policy, session negotiated actions as well as action and reason codes specifically communicated in the session or resource messages that cause the session hold transition. The MN 14 while offered the option of going into session hold can instead cancel the session, or negotiate the session resource requirements lower to fit into remaining resources, or by rebalancing resources from other active sessions. When session hold is signaled by the basestation 12 , the flexibility of these choices at the MN 14 is reduced or lost but the complexity of managing such choices is moved to the basestation 12 . [0095] As can be appreciated from the foregoing, the present invention permits a mobile host, e.g. mobile node 14 , to maintain session state with its session peers whilst the resources for the session are temporarily lost. The session response to a resource shortage can be signaled either by the basestation 12 of the affected mobile node 14 , or by the mobile node 14 itself. In addition, resource shortages can be detected both by the MN 14 and by the basestation 12 , and in the basestation 12 case a signaling exchange can be initiated with affected MNs 14 , 16 to enable an auction of the available resource to be undertaken so the least important session from the users perspective is eventually deprived of resource. The MN 14 or basestation 12 can then respond to resource availability by allowing the session to once again access resources and continue with the session. During resource unavailability, affected sessions are put on hold and the session endpoints given an action to perform such as playing a tome or displaying a message. [0096] The techniques of the present invention can be applied to a wide range of IP based mobile communications applications including E-mail, voice communications, and mobile game applications. Consider application of the invention to a game were a number of players are in a game with multiple players in the same cell. The game server multicasts out game play changes to the players and receives individual player actions via unicast from each player. [0097] If a MN 14 loses uplink resources then the MN 14 can signal to the game server, e.g., basestation 12 in the case of this example, its absence and the game server will freeze the players activity in the game in such a way that the player is not harmed, e.g., the player goes invisible and/or is moved randomly by server so that return spot is unknown, protected from weapons, power stops waning etc. Meanwhile the game server 12 informs all other players of the status change through the multicast game play information, potentially periodically flashing the invisible user as it randomly moves the absent player through the game topology. [0098] When the MN 14 returns, e.g., transitions from session hold to session on, the server 12 puts the player back in a safe spot in the game. If the MN 14 does not return then the absent status times out and the player is moved into a saved state. Meanwhile, the MN 14 can still see others progress in the game. [0099] The MN 14 game software can include a special button that enables the MN 14 to increase its resource priority in the cell 10 which the MN 14 , e.g., incurring a higher price charge for services. It is pp to the MN 14 whether it uses the priority upgrade feature but when enabled it is applied for a fixed period of time, a bit like gaining more weapons in a game because better scheduling means lower latency and an advantage with respect to other players. [0100] If the game play from the central server 12 is lost then the game instructions in the MN 14 become useless because the MN 14 cannot see the effects of its actions on the game play. Therefore, both uplink and downlink are lost together for the various players in the affected cell 10 and they go into the absent state by the basestation 12 sending the required session message stating the affected users. The basestation 12 also multicasts a single message to the MNs 14 , 16 to indicate that they are in absent state. As they independently change cells so they independently can rejoin the game. If the players in the cell 10 press the improved resource button then they contribute to the resource flow being resurrected and share the cost for the upgrade in service priority. [0101] The response to the absent message might include a trigger for the MN 14 to go into a local game play mode where the user can change configurations as part of the game (change car, weapons, pick a return spot etc) so that when gameplay returns the user has not be wasting time, twiddling thumbs and the new configuration can be sent to the server 12 . If only the uplink is lost then the MN 14 can still play within the static environment of the game by deciding where they will return and with what weapons etc so that when the uplink returns they can rejoin very quickly in a very active state. [0102] In addition, it is possible to implement a very low bitrate gameplay channel still being available so that the user has some high-level sense of what is happening in the game even when full participation is not possible due to communications resource limitations. [0103] The multi-user game example is just one exemplary application in which the methods and apparatus of the present invention can be used.

This invention describes how combined session and resource tracking in a mobile node (MN) and/or basestation in a dynamic network resource environment can be used to control reactions to resource shortages. The session that is to experience a resource shortage is detected either by the MN, or communicated to the MN where session signaling is used to modify the session according to MN and basestation policy/configuration. The basestation can alternatively modify the session itself with all the session peers, on behalf of the MN. The specific new reaction to resource shortages that is then enabled is to place the session on hold such that the resources are freed, but so that the session state is maintained in the peers. This is preferable to dropping the session, as is generally the case in dynamic environments, if the likely period of resource loss is short and the session modifications require less overhead than restarting the session when the resources return after dropping the session. In addition, before having resources removed, the basestation can provide the MN with an opportunity to upgrade the priority of its resource request compared to other users in the cell, so that a resource auction is conducted to decide which MN actually loses its resources.

CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 09/378,124, filed Aug. 19, 1999, now U.S. Pat. No. 6,325,146 which claims the benefit of the filing date of provisional application serial No. 60/127,106, filed Mar. 31, 1999, such prior applications being incorporated by reference herein in their entirety. BACKGROUND OF THE INVENTION The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a method of performing a downhole test of a subterranean formation. In a typical well test known as a drill stem test, a drill string is installed in a well with specialized drill stem test equipment interconnected in the drill string. The purpose of the test is generally to evaluate the potential profitability of completing a particular formation or other zone of interest, and thereby producing hydrocarbons from the formation. Of course, if it is desired to inject fluid into the formation, then the purpose of the test may be to determine the feasibility of such an injection program. In a typical drill stem test, fluids are flowed from the formation, through the drill string and to the earth's surface at various flow rates, and the drill string may be closed to flow therethrough at least once during the test. Unfortunately, the formation fluids have in the past been exhausted to the atmosphere during the test, or otherwise discharged to the environment, many times with hydrocarbons therein being burned off in a flare. It will be readily appreciated that this procedure presents not only environmental hazards, but safety hazards as well. Therefore, it would be very advantageous to provide a method whereby a formation may be tested, without discharging hydrocarbons or other formation fluids to the environment, or without flowing the formation fluids to the earth's surface. It would also be advantageous to provide apparatus for use in performing the method. SUMMARY OF THE INVENTION In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method is provided in which a formation test is performed downhole, without flowing formation fluids to the earth's surface, or without discharging the fluids to the environment. Also provided are associated apparatus for use in performing the method. In one aspect of the present invention, a method includes steps wherein a formation is perforated, and fluids from the formation are flowed into a large surge chamber associated with a tubular string installed in the well. Of course, if the well is uncased, the perforation step is unnecessary. The surge chamber may be a portion of the tubular string. Valves are provided above and below the surge chamber, so that the formation fluids may be flowed, pumped or reinjected back into the formation after the test, or the fluids may be circulated (or reverse circulated) to the earth's surface for analysis. In another aspect of the present invention, a method includes steps to wherein fluids from a first formation are flowed into a tubular string installed in the well, and the fluids are then disposed of by injecting the fluids into a second formation. The disposal operation may be performed by alternately applying fluid pressure to the tubular string, by operating a pump in the tubular string, by taking advantage of a pressure differential between the formations, or by other means. A sample of the formation fluid may conveniently be brought to the earth's surface for analysis by utilizing apparatus provided by the present invention. In yet another aspect of the present invention, a method includes steps wherein fluids are flowed from a first formation and into a second formation utilizing an apparatus which may be conveyed into a tubular string positioned in the well. The apparatus may include a pump which may be driven by fluid flow through a fluid conduit, such as coiled tubing, attached to the apparatus. The apparatus may also include sample chambers therein for retrieving samples of the formation fluids. In each of the above methods, the apparatus associated therewith may include various fluid property sensors, fluid and solid identification sensors, flow control devices, instrumentation, data communication devices, samplers, etc., for use in analyzing the test progress, for analyzing the fluids and/or solid matter flowed from the formation, for retrieval of stored test data, for real time analysis and/or transmission of test data, etc. These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a well wherein a first method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 2 is a schematic cross-sectional view of a well wherein a second method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 3 is an enlarged scale schematic cross-sectional view of a device which may be used in the second method; FIG. 4 is a schematic cross-sectional view of a well wherein a third method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 5 is an enlarged scale schematic cross-sectional view of a device which may be used in the third method; and FIG. 6 is a schematic cross-sectional view of a well wherein a fourth method and apparatus embodying principles of the present invention are utilized for testing a formation. DETAILED DESCRIPTION Representatively illustrated in FIG. 1 is a method 10 which embodies principles of the present invention. In the following description of the method 10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., without departing from the principles of the present invention. In the method 10 as representatively depicted in FIG. 1, a wellbore 12 has been drilled intersecting a formation or zone of interest 14 , and the wellbore has been lined with casing 16 and cement 17 . In the further description of the method 10 below, the wellbore 12 is referred to as the, interior of the casing 16 , but it is to be clearly understood that, with appropriate modification in a manner well understood by those skilled in the art, a method incorporating principles of the present invention may be performed in an uncased wellbore, and in that situation the wellbore would more appropriately refer to the uncased bore of the well. A tubular string 18 is conveyed into the wellbore 12 . The string 18 may consist mainly of drill pipe, or other segmented tubular members, or it may be substantially unsegmented, such as coiled tubing. At a lower end of the string 18 , a formation test assembly 20 is interconnected in the string. The assembly 20 includes the following items of equipment, in order beginning at the bottom of the assembly as representatively depicted in FIG. 1 : one or more generally tubular waste chambers 22 , an optional packer 24 , one or more perforating guns 26 , a firing head 28 , a circulating valve 30 , a packer 32 , a circulating valve 34 , a gauge carrier 36 with associated gauges 38 , a tester valve 40 , a tubular surge chamber 42 , a tester valve 44 , a data access sub 46 , a safety circulation valve 48 , and a slip joint 50 . Note that several of these listed items of equipment are optional in the method 10 , other items of equipment may be substituted for some of the listed items of equipment, and/or additional items of equipment may be utilized in the method and, therefore, the assembly depicted in FIG. 1 is to be considered as merely representative of an assembly which may be used in a method incorporating principles of the present invention, and not as an assembly which must necessarily be used in such method. The waste chambers 22 may be comprised of hollow tubular members, for example, empty perforating guns (i.e., with no perforating charges therein). The waste chambers 22 are used in the method 10 to collect waste from the wellbore 12 immediately after the perforating gun 26 is fired to perforate the formation 14 . This waste may include perforating debris, wellbore fluids, formation fluids, formation sand, etc. Additionally, the pressure reduction in the wellbore 12 created when the waste chambers 22 are opened to the wellbore may assist in cleaning perforations 52 created by the perforating gun 26 , thereby enhancing fluid flow from the formation 14 during the test. In general, the waste chambers 22 are utilized to collect waste from the wellbore 12 and perforations 52 prior to performing the actual formation test, but other purposes may be served by the waste chambers, such as drawing unwanted fluids out of the formation 14 , for example, fluids injected therein during the well drilling process. The packer 24 may be used to straddle the formation 14 if another formation therebelow is open to the wellbore 12 , a large rathole exists below the formation, or if it is desired to inject fluids flowed from the formation 14 into another fluid disposal formation as described in more detail below. The packer 24 is shown unset in FIG. 1 as an indication that its use is not necessary in the method 10 , but it could be included in the string 18 , if desired. The perforating gun 26 and associated firing head 28 may be any conventional means of forming an opening from the wellbore 12 to the formation 14 . Of course, as described above, the well may be uncased at its intersection with the formation 14 . Alternatively, the formation 14 may be perforated before the assembly 20 is conveyed into the well, the formation may be perforated by conveying a perforating gun through the assembly after the assembly is conveyed into the well, etc. The circulating valve 30 is used to selectively permit fluid communication between the wellbore 12 and the interior of the assembly 20 below the packer 32 , so that formation fluids may be drawn into the interior of the assembly above the packer. The circulating valve 30 may include openable ports 54 for permitting fluid flow therethrough after the perforating gun 26 has fired and waste has been collected in the waste chambers 22 . The packer 32 isolates an annulus 56 above the packer formed between the string 18 and the wellbore 12 from the wellbore below the packer. As depicted in FIG. 1, the packer 32 is set in the wellbore 12 when the perforating gun 26 is positioned opposite the formation 14 , and before the gun is fired. The circulating valve 34 may be interconnected above the packer 32 to permit circulation of fluid through the assembly 20 above the packer, if desired. The gauge carrier 36 and associated gauges 38 are used to collect test data, such as pressure, temperature, etc., during the formation test. It is to be clearly understood that the gauge carrier 36 is merely representative of a variety of means which may be used to collect such data For example, pressure and/or temperature gauges may be included in the surge chamber 42 and/or the waste chambers 22 . Additionally, note that the gauges 38 may acquire data from the interior of the assembly 20 and/or from the annulus 56 above and/or below the packer 32 . Preferably, one or more of the gauges 38 , or otherwise positioned gauges, records fluid pressure and temperature in the annulus 56 below the packer 32 , and between the packers 24 , 32 if the packer 24 is used, substantially continuously during the formation test. The tester valve 40 selectively permits fluid flow axially therethrough and/or laterally through a sidewall thereof. For example, the tester valve 40 may be an Omni™ valve, available from Halliburton Energy Services, Inc., in which case the valve may include a sliding sleeve valve 58 and closeable circulating ports 60 . The valve 58 selectively permits and prevents fluid flow axially through the assembly 20 , and the ports 60 selectively permit and prevent fluid communication between the interior of the surge chamber 42 and the annulus 56 . Other valves, and other types of valves, may be used in place of the representatively illustrated valve 40 , without departing from the principles of the present invention. The surge chamber 42 comprises one or more generally hollow tubular members, and may consist mainly of sections of drill pipe, or other conventional tubular goods, or may be purpose-built for use in the method 10 . It is contemplated that the interior of the surge chamber 42 may have a relatively large volume, such as approximately 20 barrels, so that, during the formation test, a substantial volume of fluid may be flowed from the formation 14 into the chamber, a sufficiently low initial drawdown pressure may be achieved during the test, etc. When conveyed into the well, the interior of the surge chamber 42 may be at atmospheric pressure, or it may be at another pressure, if desired. One or more sensors, such as sensor 62 , may be included with the chamber 42 , in order to acquire data, such as fluid property data (e.g., pressure, temperature, resistivity, viscosity, density, flow rate, etc.) and/or fluid identification data (e.g., by using nuclear magnetic resonance sensors available from Numar, Inc.). The sensor 62 may be in data communication with the data access sub 46 , or another remote location, by any data transmission means, for example, a line 64 extending external or internal relative to the assembly 20 , acoustic data transmission, electromagnetic data transmission, optical data transmission, etc. The valve 44 may be similar to the valve 40 described above, or it may be another type of valve. As representatively depicted in FIG. 1, the valve 44 includes a ball valve 66 and closeable circulating ports 68 . The ball valve 66 selectively permits and prevents fluid flow axially through the assembly 20 , and the ports 68 selectively permit and prevent fluid communication between the interior of the assembly 20 above the surge chamber 42 and the annulus 56 . Other valves, and other types of valves, may be used in place of the representatively illustrated valve 44 , without departing from the principles of the present invention. The data access sub 46 is representatively depicted as being of the type wherein such access is provided by conveying a wireline tool 70 therein in order to acquire the data transmitted from the sensor 62 . For example, the data access sub 46 may be a conventional wet connect sub. Such data access may be utilized to retrieve stored data and/or to provide real time access to data during the formation test. Note that a variety of other means may be utilized for accessing data acquired downhole in the method 10 , for example, the data may be transmitted directly to a remote location, other types of tools and data access subs may be utilized, etc. The safety circulation valve 48 may be similar to the valves 40 , 44 described above in that it may selectively permit and prevent fluid flow axially therethrough and through a sidewall thereof. However, preferably the valve 48 is of the type which is used only when a well control emergency occurs. In that instance, a ball valve 72 thereof (which is shown in its typical open position in FIG. 1) would be closed to prevent any possibility of formation fluids flowing further to the earth's surface, and circulation ports 74 would be opened to permit kill weight fluid to be circulated through the string 18 . The slip joint 50 is utilized in the method 10 to aid in positioning the assembly 20 in the well. For example, if the string 18 is to be landed in a subsea wellhead, the slip joint 50 may be useful in spacing out the assembly 20 relative to the formation 14 prior to setting the packer 32 . In the method 10 , the perforating guns 26 are positioned opposite the formation 14 and the packer 32 is set. If it is desired to isolate the formation 14 from the wellbore 12 below the formation, the optional packer 24 may be included in the string 18 and set so that the packers 32 , 24 straddle the formation. The formation 14 is perforated by firing the gun 26 , and the waste chambers 22 are immediately and automatically opened to the wellbore 12 upon such gun firing. For example, the waste chambers 22 may be in fluid communication with the interior of the perforating gun 26 , so that when the gun is fired, flow paths are provided by the detonated perforating charges through the gun sidewall. Of course, other means of providing such fluid communication may be provided, such as by a pressure operated device, a detonation operated device, etc., without departing from the principles of the present invention. At this point, the ports 54 may or may not be open, as desired, but preferably the ports are open when the gun 26 is fired. If not previously opened, the ports 54 are opened after the gun 26 is fired. This permits flow of fluids from the formation 14 into the interior of the assembly 20 above the packer 32 . When it is desired to perform the formation test, the tester valve 40 is opened by opening the valve 58 , thereby permitting the formation fluids to flow into the surge chamber 42 and achieving a drawdown on the formation 14 . The gauges 38 and sensor 62 acquire data indicative of the test, which, as described above, may be retrieved later or evaluated simultaneously with performance of the test. One or more conventional fluid samplers 76 may be positioned within, or otherwise in communication with, the chamber 42 for collection of one or more samples of the formation fluid. One or more of the fluid samplers 76 may also be positioned within, or otherwise in communication with, the waste chambers 22 . After the test, the valve 66 is opened and the ports 60 are opened, and the formation fluids in the surge chamber 42 are reverse circulated out of the chamber. Other circulation paths, such as the circulating valve 34 , may also be used. Alternatively, fluid pressure may be applied to the string 18 at the earth's surface before unsetting the packer 32 , and with valves 58 , 66 open, to flow the formation fluids back into the formation 14 . As another alternative, the assembly 20 may be repositioned in the well, so that the packers 24 , 32 straddle another formation intersected by the well, and the formation fluids may be flowed into this other formation. Thus, it is not necessary in the method 10 for formation fluids to be conveyed to the earth's surface unless desired, such as in the sampler 76 , or by reverse circulating the formation fluids to the earth's surface. Referring additionally now to FIG. 2, another method 80 embodying principles of the present invention is representatively depicted. In the method 80 , formation fluids are transferred from a formation 82 from which they originate, into another formation 84 for disposal, without it being necessary to flow the fluids to the earth's surface during a formation test, although the fluids may be conveyed to the earth's surface if desired. As depicted in FIG. 2, the disposal formation 84 is located uphole from the tested formation 82 , but it is to be clearly understood that these relative positionings could be reversed with appropriate changes to the apparatus and method described below, without departing from the principles of the present invention. A formation test assembly 86 is conveyed into the well interconnected in a tubular string 87 at a lower end thereof. The assembly 86 includes the following, listed beginning at the bottom of the assembly: the waste chambers 22 , the packer 24 , the gun 26 , the firing head 28 , the circulating valve 30 , the packer 32 , the circulating valve 34 , the gauge carrier 36 , a variable or fixed choke 88 , a check valve 90 , the tester valve 40 , a packer 92 , an optional pump 94 , a disposal sub 96 , a packer 98 , a circulating valve 100 , the data access sub 46 , and the tester valve 44 . Note that several of these listed items of equipment are optional in the method 80 , other items of equipment may be substituted for some of the listed items of equipment, and/or additional items of equipment may be utilized in the method and, therefore, the assembly 86 depicted in FIG. 2 is to be considered as merely representative of an assembly which may be used in a method incorporating principles of the present invention, and not as an assembly which must necessarily be used in such method. For example, the valve 40 , check valve 90 and choke 88 are shown as examples of flow control devices which may be installed in the assembly 86 between the formations 82 , 84 , and other flow control devices, or other types of flow control devices, may be utilized in the method 80 , in keeping with the principles of the present invention. As another example, the pump 94 may be used, if desired, to pump fluid from the test formation 82 , through the assembly 86 and into the disposal formation 84 , but use of the pump 94 is not necessary in the method 80 . Additionally, many of the items of equipment in the assembly 86 are shown as being the same as respective items of equipment used in the method 10 described above, but this is not necessarily the case. When the assembly 86 is conveyed into the well, the disposal formation 84 may have already been perforated, or the formation may be perforated by providing one or more additional perforating guns in the assembly, if desired. For example, additional perforating guns could be provided below the waste chambers 22 in the assembly 86 . The assembly 86 is positioned in the well with the gun 26 opposite the test formation 82 , the packers 24 , 32 , 92 , 98 are set, the circulating valve 30 is opened, if desired, if not already open, and the gun 26 is fired to perforate the formation. At this point, with the test formation 82 perforated, waste is immediately received into the waste chambers 22 as described above for the method 10 . The circulating valve 30 is opened, if not done previously, and the test formation is thereby placed in fluid communication with the interior of the assembly 86 . Preferably, when the assembly 86 is positioned in the well as shown in FIG. 2, a relatively low density fluid (liquid, gas (including air, at atmospheric or greater or lower pressure) and/or combinations of liquids and gases, etc.) is contained in the string 87 above the upper valve 44 . This creates a low hydrostatic pressure in the string 87 relative to fluid pressure in the test formation 82 , which pressure differential is used to draw fluids from the test formation into the assembly 86 as described more fully below. Note that the fluid preferably has a density which will create a pressure differential from the formation 82 to the interior of the assembly at the ports 54 when the valves 58 , 66 are open. However, it is to be clearly understood that other methods and means of drawing formation fluids into the assembly 86 may be utilized, without departing from the principles of the present invention. For example, the low density fluid could be circulated into the string 87 after positioning it in the well by opening the ports 68 , nitrogen could be used to displace fluid out of the string, a pump 94 could be used to pump fluid from the test formation 82 into the string, a difference in formation pressure between the two formations 82 , 84 could be used to induce flow from the higher pressure formation to the lower pressure formation, etc. After perforating the test formation 82 , fluids are flowed into the assembly 86 via the circulation valve 30 as described above, by opening the valves 58 , 66 . Preferably, a sufficiently large volume of fluid is initially flowed out of the test formation 82 , so that undesired fluids, such as drilling fluid, etc., in the formation are withdrawn from the formation. When one or more sensors, such as a resistivity or other fluid property or fluid identification sensor 102 , indicates that representative desired formation fluid is flowing into the assembly 86 , the lower valve 58 is closed. Note that the sensor 102 may be of the type which is utilized to indicate the presence and/or identity of solid matter in the formation fluid flowed into the assembly 86 . Pressure may then be applied to the string 87 at the earth's surface to flow the undesired fluid out through check valves 104 and into the disposal formation 84 . The lower valve 58 may then be opened again to flow further fluid from the test formation 82 into the assembly 86 . This process may be repeated as many times as desired to flow substantially any volume of fluid from the formation 82 into the assembly 86 , and then into the disposal formation 84 . Data acquired by the gauges 38 and/or sensors 102 while fluid is flowing from the formation 82 through the assembly 86 (when the valves 58 , 66 are open), and while the formation 82 is shut in (when the valve 58 is closed) may be analyzed after or during the test to determine characteristics of the formation 82 . Of course, gauges and sensors of any type may be positioned in other portions of the assembly 86 , such as in the waste chambers 22 , between the valves 58 , 66 , etc. For example, pressure and temperature sensors and/or gauges may be positioned between the valves 58 , 66 , which would enable the acquisition of data useful for injection testing of the disposal zone 84 , during the time the lower valve 58 is closed and fluid is flowed from the assembly 86 outward into the formation 84 . It will be readily appreciated that, in this fluid flowing process as described above, the valve 58 is used to permit flow upwardly therethrough, and then the valve is closed when pressure is applied to the string 87 to dispose of the fluid. Thus, the valve 58 could be replaced by the check valve 90 , or the check valve may be supplied in addition to the valve as depicted in FIG. 2 . If a difference in formation pressure between the formations 82 , 84 is used to flow fluid from the formation 82 into the assembly 86 , then a variable choke 88 may be used to regulate this fluid flow. Of course, the variable choke 88 could be provided in addition to other flow control devices, such as the valve 58 and check valve 90 , without departing from the principles of the present invention. If a pump 94 is used to draw fluid into the assembly 86 , no flow control devices may be needed between the disposal formation 84 and the test formation 82 , the same or similar flow control devices depicted in FIG. 2 may be used, or other flow control devices may be used. Note that, to dispose of fluid drawn into the assembly 86 , the pump 94 is operated with the valve 66 closed. In a similar manner, the check valves 104 of the disposal sub 96 may be replaced with other flow control devices, other types of flow control devices, etc. To provide separation between the low density fluid in the string 87 and the fluid drawn into the assembly 86 from the test formation 82 , a fluid separation device or plug 106 which may be reciprocated within the assembly 86 may be used. The plug 106 would also aid in preventing any gas in the fluid drawn into the assembly 86 from being transmitted to the earth's surface. An acceptable plug for this application is the Omega™ plug available from Halliburton Energy Services, Inc. Additionally, the plug 106 may have a fluid sampler 108 attached thereto, which may be activated to take a sample of the formation fluid drawn into the assembly 86 when desired. For example, when the sensor 102 indicates that the desired representative formation fluid has been flowed into the assembly 86 , the plug 106 may be deployed with the sampler 108 attached thereto in order to obtain a sample of the formation fluid. The plug 106 may then be reverse circulated to the earth's surface by opening the circulation valve 100 . Of course, in that situation, the plug 106 should be retained uphole from the valve 100 . A nipple, no-go 110 , or other engagement device may be provided to prevent the plug 106 from displacing downhole past the disposal sub 96 . When applying pressure to the string 87 to flow the fluid in the assembly 86 outward into the disposal formation 84 , such engagement between the plug 106 and the device 110 may be used to provide a positive indication at the earth's surface that the pumping operation is completed. Additionally, a no-go or other displacement limiting device could be used to prevent the plug 106 from circulating above the upper valve 44 to thereby provide a type of downhole safety valve, if desired. The sampler 108 could be configured to take a sample of the fluid in the assembly 86 when the plug 106 engages the device 110 . Note, also, that use of the device 110 is not necessary, since it may be desired to take a sample with the sampler 108 of fluid in the assembly 86 below the disposal sub 96 , etc. The sampler could alternatively be configured to take a sample after a predetermined time period, in response to pressure applied thereto (such as hydrostatic pressure), etc. An additional one of the plug 106 may be deployed in order to capture a sample of the fluid in the assembly 86 between the plugs, and then convey this sample to the surface, with the sample still retained between the plugs. This may be accomplished by use of a plug deployment sub, such as that representatively depicted in FIG. 3 . Thus, after fluid from the formation 82 is drawn into the assembly 86 , the second plug 106 is deployed, thereby capturing a sample of the fluid between the two plugs. The sample may then be circulated to the earth's surface between the two plugs 106 by, for example, opening the circulating valve 100 and reverse circulating the sample and plugs uphole through the string 87 . Referring additionally now to FIG. 3, a fluid separation device or plug deployment sub 112 embodying principles of the present invention is representatively depicted. A plug 106 is releasably secured in a housing 114 of the sub 112 by positioning it between two radially reduced restrictions 116 . If the plug 106 is an Omega™ plug, it is somewhat flexible and can be made to squeeze through either of the restrictions 116 if a sufficient pressure differential is applied across the plug. Of course, either of the restrictions could be made sufficiently small to prevent passage of the plug 106 therethrough, if desired. For example, if it is desired to permit the plug 106 to displace upwardly through the assembly 86 above the sub 112 , but not to displace downwardly past the sub 112 , then the lower restriction 116 may be made sufficiently small, or otherwise configured, to prevent passage of the plug therethrough. A bypass passage 118 formed in a sidewall of the housing 114 permits fluid flow therethrough from above, to below, the plug 106 , when a valve 120 is open. Thus, when fluid is being drawn into the assembly 86 in the method 80 , the sub 112 , even though the plug 106 may remain stationary with respect to the housing 114 , does not effectively prevent fluid flow through the assembly. However, when the valve 120 is closed, a pressure differential may be created across the plug 106 , permitting the plug to be deployed for reciprocal movement in the string 87 . The sub 112 may be interconnected in the assembly 86 , for example, below the upper valve 66 and below the plug 106 shown in FIG. 2 . If a pump, such as pump 94 is used to draw fluid from the formation 82 into the assembly 86 , then use of the low density fluid in the string 87 is unnecessary. With the upper valve 66 closed and the lower valve 58 open, the pump 94 may be operated to flow fluid from the formation 82 into the assembly 86 , and outward through the disposal sub 96 into the disposal formation 84 . The pump 94 may be any conventional pump, such as an electrically operated pump, a fluid operated pump, etc. Referring additionally now to FIG. 4, another method 130 of performing a formation test embodying principles of the present invention is representatively depicted. The method 130 is described herein as being used in a “rigless” scenario, i.e., in which a drilling rig is not present at the time the actual test is performed, but it is to be clearly understood that such is not necessary in keeping with the principles of the present invention. Note that the method 80 could also be performed rigless, if a downhole pump is utilized in that method. Additionally, although the method 130 is depicted as being performed in a subsea well, a method incorporating principles of the present invention may be performed on land as well. In the method 130 , a tubular string 132 is positioned in the well, preferably after a test formation 134 and a disposal formation 136 have been perforated. However, it is to be understood that the formations 134 , 136 could be perforated when or after the string 132 is conveyed into the well. For example, the string 132 could include perforating guns, etc., to perforate one or both of the formations 134 , 136 when the string is conveyed into the well. The string 132 is preferably constructed mainly of a composite material, or another easily milled/drilled material. In this manner, the string 132 may be milled/drilled away after completion of the test, if desired, without the need of using a drilling or workover rig to pull the string. For example, a coiled tubing rig could be utilized, equipped with a drill motor, for disposing of the string 132 . When initially run into the well, the string 132 may be conveyed therein using a rig, but the rig could then be moved away, thereby providing substantial cost savings to the well operator. In any event, the string 132 is positioned in the well and, for example, landed in a subsea wellhead 138 . The string 132 includes packers 140 , 142 , 144 . Another packer may be provided if it is desired to straddle the test formation 134 , as the test formation 82 is straddled by the packers 24 , 32 shown in FIG. 2 . The string 132 further includes ports 146 , 148 , 150 spaced as shown in FIG. 4, i.e., ports 146 positioned below the packer 140 , ports 148 between the packers 142 , 144 , and ports 150 above the packer 144 . Additionally the string 132 includes seal bores 152 , 154 , 156 , 158 and a latching profile 160 therein for engagement with a tester tool 162 as described more fully below. The tester tool 162 is preferably conveyed into the string 132 via coiled tubing 164 of the type which has an electrical conductor 165 therein, or another line associated therewith, which may be used for delivery of electrical power, data transmission, etc., between the tool 162 and a remote location, such as a service vessel 166 . The tester tool 162 could alternatively be conveyed on wireline or electric line. Note that other methods of data transmission, such as acoustic, electromagnetic, fiber optic etc. may be utilized in the method 130 , without departing from the principles of the present invention. A return flow line 168 is interconnected between the vessel 166 and an annulus 170 formed between the string 132 and the wellbore 12 above the upper packer 144 . This annulus 170 is in fluid communication with the ports 150 and permits return circulation of fluid flowed to the tool 162 via the coiled tubing 164 for purposes described more fully below. The ports 146 are in fluid communication with the test formation 134 and, via the interior of the string 132 , with the lower end of the tool 162 . As described below, the tool 162 is used to pump fluid from the formation 134 , via the ports 146 , and out into the disposal formation 136 via the ports 148 . Referring additionally now to FIG. 5, the tester tool 162 is schematically and representatively depicted engaged within the string 132 , but apart from the remainder of the well as shown in FIG. 4 for illustrative clarity. Seals 172 , 174 , 176 , 178 sealingly engage bores 152 , 154 , 156 , 158 , respectively. In this manner, a flow passage 180 near the lower end of the tool 162 is in fluid communication with the interior of the string 132 below the ports 148 , but the passage is isolated from the ports 148 and the remainder of the string above the seal bore 152 ; a passage 182 is placed in fluid communication with the ports 148 between the seal bores 152 , 154 and, thereby, with the disposal formation 136 ; and a passage 184 is placed in fluid communication with the ports 150 between the seal bores 156 , 158 and, thereby, with the annulus 170 . An upper passage 186 is in fluid communication with the interior of the coiled tubing 164 . Fluid is pumped down the coiled tubing 164 and into the tool 162 via the passage 186 , where it enters a fluid motor or mud motor 188 . The motor 188 is used to drive a pump 190 . However, the pump 190 could be an electrically-operated pump, in which case the coiled tubing 164 could be a wireline and the passages 186 , 184 , seals 176 , 178 , seal bores 156 , 158 , and ports 150 would be unnecessary. The pump 190 draws fluid into the tool 162 via the passage 180 , and discharges it from the tool via the passage 182 . The fluid used to drive the motor 188 is discharged via the passage 184 , enters the annulus, and is returned via the line 168 . Interconnected in the passage 180 are a valve 192 , a fluid property sensor 194 , a variable choke 196 , a valve 198 , and a fluid identification sensor 200 . The fluid property sensor 194 may be a pressure, temperature, resistivity, density, flow rate, etc. sensor, or any other type of sensor, or combination of sensors, and may be similar to any of the sensors described above. The fluid identification sensor 200 may be a nuclear magnetic resonance sensor, an acoustic sand probe, or any other type of sensor, or combination of sensors. Preferably, the sensor 194 -is used to obtain data regarding physical properties of the fluid entering the tool 162 , and the sensor 200 is used to identify the fluid itself, or any solids, such as sand, carried therewith. For example, if the pump 190 is operated to produce a high rate of flow from the formation 134 , and the sensor 200 indicates that this high rate of flow results in an undesirably large amount of sand production from the formation, the operator will know to produce the formation at a lower flow rate. By pumping at different rates, the operator can determine at what fluid velocity sand is produced, etc. The sensor 200 may also enable the operator to tailor a gravel pack completion to the grain size of the sand identified by the sensor during the test. The flow controls 192 , 196 , 198 are merely representative of flow controls which may be provided with the tool 162 . These are preferably electrically operated by means of the electrical line 165 associated with the coiled tubing 164 as described above, although they may be otherwise operated, without departing from the principles of the present invention. After exiting the pump 190 , fluid from the formation 134 is discharged into the passage 182 . The passage 182 has valves 202 , 204 , 206 , sensor 208 , and sample chambers 210 , 212 associated therewith. The sensor 208 may be of the same type as the sensor 194 , and is used to monitor the properties, such as pressure, of the fluid being injected into the disposal formation 136 . Each sample chamber has a valve 214 , 216 for interconnecting the chamber to the passage 182 and thereby receiving a sample therein. Each sample chamber may also have another valve 218 , 220 (shown in dashed lines in FIG. 5) for discharge of fluid from the sample chamber into the passage 182 . Each of the valves 202 , 204 , 206 , 214 , 216 , 218 , 220 may be electrically operated via the coiled tubing 164 electrical line as described above. The sensors 194 , 200 , 208 may be interconnected to the line 165 for transmission of data to a remote location. Of course, other means of transmitting this data, such as acoustic, electromagnetic, etc., may be used in addition, or in the alternative. Data may also be stored in the tool 162 for later retrieval with the tool. To perform a test, the valves 192 , 198 , 204 , 206 are opened and the pump 190 is operated by flowing fluid through the passages 184 , 186 via the coiled tubing 164 . Fluid from the formation 134 is, thus, drawn into the passage 180 and discharged through the passage 182 into the disposal formation 136 as described above. When one or more of the sensors 194 , 200 indicate that desired representative formation fluid is flowing through the tool 162 , one or both of the samplers 210 , 212 is opened via one or more of the valves 214 , 216 , 218 , 220 to collect a sample of the formation fluid. The valve 206 may then be closed, so that the fluid sample may be pressurized to the formation 134 pressure in the samplers 210 , 212 before closing the valves 214 , 216 , 218 , 220 . One or more electrical heaters 222 may be used to keep a collected sample at a desired reservoir temperature as the tool 162 is retrieved from the well after the test. Note that the pump 190 could be operated in reverse to perform an injection test on the formation 134 . A microfracture test could also be performed in this manner to collect data regarding hydraulic fracturing pressures, etc. Another formation test could be performed after the microfracture test to evaluate the results of the microfracture operation. As another alternative, a chamber of stimulation fluid, such as acid, could be carried with the tool 162 and pumped into the formation 134 by the pump 190 . Then, another formation test could be performed to evaluate the results of the stimulation operation. Note that fluid could also be pumped directly from the passage 186 to the passage 180 using a suitable bypass passage 224 and valve 226 to directly pump stimulation fluids into the formation 134 , if desired. The valve 202 is used to flush the passage 182 with fluid from the passage 186 , if desired. To do this, the valves 202 , 204 , 206 are opened and fluid is circulated from the passage 186 , through the passage 182 , and out into the wellbore 12 via the port 148 . Referring additionally now to FIG. 6, another method 240 embodying principles of the present invention is representatively illustrated. The method 240 is similar in many respects to the method 130 described above, and elements shown in FIG. 6 which are similar to those previously described are indicated using the same reference numbers. In the method 240 , a tester tool 242 is conveyed into the wellbore 12 on coiled tubing 164 after the formations 134 , 136 have been perforated, if necessary. Of course, other means of conveying the tool 242 into the well may be used, and the formations 134 , 136 may be perforated after conveyance of the tool into the well, without departing from the principles of the present invention. The tool 242 differs from the tool 162 described above and shown in FIGS. 4 & 5 in part in that the tool 242 carries packers 244 , 246 , 248 thereon, and so there is no need to separately install the tubing string 132 in the well as in the method 130 . Thus, the method 240 may be performed without the need of a rig to install the tubing string 132 . However, it is to be clearly understood that a rig may be used in a method incorporating principles of the present invention. As shown in FIG. 6, the tool 242 has been conveyed into the well, positioned opposite the formations 134 , 136 , and the packers 244 , 246 , 248 have been set. The upper packers 244 , 246 are set straddling the disposal formation 136 . The passage 182 exits the tool 242 between the upper packers 244 , 246 , and so the passage is in fluid communication with the formation 136 . The packer 248 is set above the test formation 134 . The passage 180 exits the tool 242 below the packer 248 , and the passage is in fluid communication with the formation 134 . A sump packer 250 is shown set in the well below the formation 134 , so that the packers 248 , 250 straddle the formation 134 and isolate it from the remainder of the well, but it is to be clearly understood that use of the packer 250 is not necessary in the method 240 . Operation of the tool 242 is similar to the operation of the tool 162 as described above. Fluid is circulated through the coiled tubing string 164 to cause the motor 188 to drive the pump 190 . In this manner, fluid from the formation 134 is drawn into the tool 242 via the passage 180 and discharged into the disposal formation 136 via the passage 182 . Of course, fluid may also be injected into the formation 134 as described above for the method 130 , the pump 190 may be electrically operated (e.g., using the line 165 or a wireline on which the tool is conveyed), etc. Since a rig is not required in the method 240 , the method may be performed without a rig present, or while a rig is being otherwise utilized. For example, in FIG. 6, the method 240 is shown being performed from a drill ship 252 which has a drilling rig 254 mounted thereon. The rig 254 is being utilized to drill another wellbore via a riser 256 interconnected to a template 258 on to the seabed, while the testing operation of the method 240 is being performed in the adjacent wellbore 12 . In this manner, the well operator realizes significant cost and time benefits, since the testing and drilling operations may be performed simultaneously from the same vessel 252 . Data generated by the sensors 194 , 200 , 208 may be stored in the tool 242 for later retrieval with the tool, or the data may be transmitted to a remote location, such as the earth's surface, via the line 165 or other data transmission means. For example, electromagnetic, acoustic, or other data communication technology may be utilized to transmit the sensor 194 , 200 , 208 data in real time. Of course, a person skilled in the art would, upon a careful reading of the above description of representative embodiments of the present invention, readily appreciate that modifications, additions, substitutions, deletions and other changes may be made to these embodiments, and such changes are contemplated by the principles of the present invention. For example, although the methods 10 , 80 , 130 , 240 are described above as being performed in cased wellbores, they may also be performed in uncased wellbores, or uncased portions of wellbores, by exchanging the described packers, tester valves, etc. for their open hole equivalents. The foregoing detailed description is to be clearly understood as being given by way of illustration and example only.

Methods and apparatus are provided which permit well testing operations to be performed downhole in a subterranean well. In various described methods, fluids flowed from a formation during a test may be disposed of downhole by injecting the fluids into the formation from which they were produced, or by injecting the fluids into another formation. In several of the embodiments of the invention, apparatus utilized in the methods permit convenient retrieval of samples of the formation fluids and provide enhanced data acquisition for monitoring of the test and for evaluation of the formation fluids.

[0001] This application claims priority to Provisional Application 61/926,574 filed Jan. 13, 2014, the content of which is incorporated by reference. BACKGROUND [0002] The classical definition of degrees of freedom (DoF) deals with the degree of a communication channel or multiple communication channels at the limit of high SNR. This can be interpreted as the number of independent streams that can be sent in each communication channel at high SNR regime. [0003] Consider a point to point channel between a transmitter and a receiver both equipped with multiple antennas. It is well known that for independent Gaussian channel model between each pair of transmit and receive antennas the capacity of the corresponding multiple antenna input and multiple antenna output (MIMO) channel scales with the minimum of the number of antennas at the transmitter (N T ) and the receiver (N R ) at the limit of high SNR. The degrees of the freedom of the channel is then defined as the quantity min(N T ,N R ). The concept of degree of freedom may also be interpreted as the possibility or measure of the number of independent streams that can be transmitted simultaneously in the channel. It is immediate to see the usefulness of extending this concept in multiuser networks where we are interested to understand the number of simultaneous streams that can be transmitted between different transmit and receiver subset of the nodes in the network. For example, degrees of freedom in a three user interference channel with N antennas at each node is defined similarly as the scaling of the channel capacity between each pair of the users as a function of log(SNR). The same concept may be extended to define the three tuple d=(d 1 ,d 2 ,d 3 ) that can be achieved simultaneously, where d i denotes the scaling of the channel capacity between the i th transmitter and receiver pair. While there may be multiple choices of d achievable in this network the region of all such d defines the available degrees of freedom region. SUMMARY [0004] In one aspect, systems and methods are disclosed to operate a communication network by dividing signal dimensions at a receiver into interference and intended signal dimensions; applying transmit precoding to mitigate interference by overlapping the interference from a plurality of transmitters into the interference dimension at thea receiver; and applying a receiver filter to cancel out the interference dimension at the receiver and recover the signal in the intended signal dimension. [0005] In another aspect, systems and methods are disclosed to operate a communication network by grouping communication channels into interfering networks and intended data networks; determining degrees of freedom (DoF) per communication node where at a transmitting node the DoF is the number of independent dimensions for the transmission and at each receiver node the DoF is the number of independent dimensions for receiving data signals; separately dealing with interference in the network from communication in the intended data network through successive application of interference removal over partial interference network, and performing interference alignment in a cellular network and minimizing interference in single or multiple cells. [0006] Advantages of the system may include one or more of the following. The system solves interference alignment issue which has particular importance in the context of cellular networks and the system can address interference in single or multiple cells especially when full duplex radios are possible to use. The use of full duplex in cellular systems can be done by characterizing the gain of using full duplex access point versus using half duplex access point. By exchanging HD APs to FD Aps, a doubling of the spectral efficiency is possible in single cell or 2-cell network with full cooperation between their access points. As we discussed the scalability of throughput in a wireless systems with multiple cells requires tight coordination between the access point. However, recent work have shown that global coordination and information exchange is not in fact necessary due to the fact that the interference is usually strong in a local vicinity and would not spread in the network globally. Therefore huge complexity and overhead of the global information exchange and the exhaustive burden of implementing a tight coordination between all access points can be replaced by coordination between neighboring cells that is much more manageable. We note that similar local coordination might be enough for the purpose of interference alignment particularly when full duplex access points are deployed. BRIEF DESCRIPTION OF THE DRAWINGS [0007] FIGS. 1A-1B show an exemplary Full Bipartite Interference Channel (FBIN): FIG. 1A shows FBIN(4,4) while FIG. 1B shows FBIN(4,3). [0008] FIG. 2 shows an example of a communication network divided into an interference network overlayed with a desired communication network comprising of a MAC, a BC, and a single link. [0009] FIGS. 3A-3B show an exemplary Single Cell Channel with FBIN and a desired network with a MAC and a BC. DESCRIPTION [0010] We introduce the concept of DoF per communication node where at a transmitting node the DoF is the number of independent dimensions that can be used for the transmission and at each receiver node the DoF is the number of independent dimensions that can be used for receiving data signals. In general the communication channels or link in a network can be divided into two sets: the interfering channels and the intended channels; hence, the network may be considered as an overlay of two networks, respectively: the interfering network and intended data network. While in the classical form DoF is essentially a function of interfering network and is independent of the intended data network (as long as the networks are generic), the definition of DoF has been done for the channels in the intended data network. We illustrate a new interpretation of DoF that depends only on the interfering network and can be formalized in full generality based on degrees of freedom per nodes of the network. While the classical DoF has been studied only in the context of interference and X-channels, the per node DoF concept generalized the idea to other possible network. The system can express a set of new results on DoF for different networks and also make a connection to the classical definition of DoF defined in interference and X-channels. [0011] Although the definition of DoF in general is a function of the actual channel gains, it is almost universally treated under generic or randomly generated channel conditions. As we discussed earlier, we do not consider symbol or channel extension, hence, we only consider space domain treatment of the signal where the channel coefficients are fixed. In practical scenarios, it means that we consider a fixed precoder at the transmitter and receive filters per block or multiple block of transmission within the channel coherence time where the channel coefficients are approximately constant. Consider an interference channel with K transmitting nodes indexed by 1 , 2 , and 3 and the corresponding receiving nodes denoted by 4 , 5 , and 6 , respectively. The degrees of freedom corresponds to the rank of semi-orthogonal precoding matrices V i and receive filters U 1 such that the following condition holds [0000] U j H ji V i =0 ∀( i−j )≠0(mod 3)  (1) [0000] U j H ji V i =d i ∀( i−j )=0(mod 3)  (2) [0012] where U j is a d j ×N j matrix, V i is a N i ×d i matrix and N i is the number of antennas at the node i. It is not hard to see that if the channel matrices H ji are generic satisfying the first set of conditions (1) is enough and the second conditions (2) are satisfied automatically. [0013] This example reveals an important concept that the DoF in such a network is just a function of the interference network which is defined as a subset of the original network in which only the interfering links are present. In other word the desired communication or data intended network that consist of the channels over which the actual communication and signal transmission takes place (H i+3,i in the above example) does not play a direct role in the calculation of the DoF region in the network. This means that if we replace the data intended network with another network consisting of six links with the component channels H i+6,i the same DoF region is available if N i+6 ≧N i . This observation can help us decouple the problem of finding the DoF region in a network based on considering a network as an overlay of two networks defined by ‘interference network’ and ‘data intended network’ into two parts. First, we find the DoF region in the interference network and then abstract the interference network by a network with potentially less number of antennas defined by the degrees of freedom in this network and ignoring the interference network in the second step. In the second step, the channel coefficients of the data intended network are adjusted based on the precoders and receiving filters obtained in the first step which leaves us with a network without any interference but with lower dimensions. [0014] The definition of DoF in the interference network would change and depends on more parameters, in particular, each node may be denoted with a DoF per node and that defines the number of virtual antennas at this node. In a transmitting node the dimension of the precoder obtained as a solution to a given achievable DoF in the interference network defines its per node DoF and similarly at the receiving node the dimension of the receive filter does the same. Obviously, the classical definition of DoF per link in the network is still a function of the communication network as well. For example in the same 3-user interference channel we can consider a communication network that is defined as a multiple access channel from the transmitting nodes 1 , 2 , and 3 to a receiving node 7 denoted by the component channels H 7i ,i=1, 2, 3 and a broadcast channel from a single point 8 to the receiving nodes 4 , 5 , and 6 denoted by the component channels H i8 ,i=4, 5, 6. Clearly in this network the total DoF is a function of the number of antennas at the nodes 7 and 8 as well. Nonetheless, the treatment of the problem as two overlay networks of ‘interference’ and ‘desired’ network allows us to decouple the problem and also interpret the solution more easily. Also, it is possible to consider more general cases of the data intended network as illustrated in the above example which is beyond the classical form of definition of DoF that is generally considered in the context of classical interference channel and X-channels. [0015] Degrees of Freedom per Node (DoF) is defined next. We formally define DoF per node in a communication network. Consider a network of L nodes equipped with N i , i=1, 2, . . . , L antennas that are either a transmitting node or a receiving node. The communication channel defined as an oriented graph of edges E on the set of nodes where the component channel between different nodes is assumed to be a Gaussian channel denoted by the channel coefficients matrix H ji with complex entries from the transmitting node i to the receiving node j. A component channel does not exist in the graph if its channel matrix is zero. The receive signal at a receiving node j is defined as [0000] y j = ∑ i ∈ τ   H ji  x i + z j , ∀ j ∈ R ( 3 ) [0016] where T is the set of transmitting node indices, R is the set of receiving node indices, y j is the received signal at the receiving node j, x i is the transmitting signal at the transmitting node i, and z i is the Gaussian noise at the receiver of node j. [0017] The set of component channels are divided into two sets: a set D consisting of the data intended (or desired) communication link and its complement set I, (I∪D=E and I∩D=◯), that consist of the link that their output only causes interference at the receiving node and their corresponding signal does not carry any intended data to this node. [0018] We say a vector of d =(d 1 , . . . , d L ) DoF per node for the nodes 1 , . . . , L is achievable if and only if there exist a set of transmit precoders V i of size N i ×d i for the nodes iεT and a set of receive filters U j of size d j ×N j for the receiving nodes jεR such that U j H ji V i =0 simultaneously. Please note that by definition a precoder and a receive filter is a full rank semi-orthogonal matrices. [0019] The above definition of per node DoF is equivalent to the following: Let the interference network defined by the graph (T∪R, I) is amended with L links from the set E′ one connected from each transmitting node iεT to a new node in T′ and one link connected from a node in a set of new nodes R′ to a different receiving node in R where the number of antennas of the new nodes are the same as the nodes that they are connected to. We say a vector of d =(d 1 , . . . , d L ) DoF per node for the nodes 1 , . . . , L is achievable if and only if there exist a coding scheme to which achieves the capacity scaling of d i log(SNR)+o(log(SNR)) simultaneously at the limit of high SNR for all the links in E′ for the generic choice of all channels where channel extension is not allowed. [0020] The above definition clarifies that once a vector of DOF per node d is achievable it is possible to remove the interference network from the original network and replace the number of antennas at each node to d i instead of N i and update the component channel coefficients by right and left multiplication with the corresponding precoder and receive filter of transmit and receive nodes of this component channel, respectively. this change would not affect the DoF in the reminder of the network that is defined as the desired network. We point out that our analysis is solely with respect to the DoF in the network and such reduction may affect the actual capacity region of the channel differently. In particular, even different solutions for the precoders and receiver filters that correspond to the same DoF per node may also affect the desired network in such a way that the achievable capacity or throughput in the desired network is different. Nonetheless, in terms of high SNR analysis the reduction obtained by the notion of DoF per node and removal of the corresponding interference network does not change the capacity scaling. [0021] FIGS. 1A-1B show a Full Bipartite Interference Channel (FBIN): (a) FBIN(4,4) (b) FBIN(4,3). One may choose to apply the concept of DoF per node in a partial manner. Consider the problem of calculating an achievable DoF per node in an interference network defined as FBIN(4,4), depicted in FIG. 1( a ), with N=4 antennas at each node, where FBIN(L, K) denotes a full bipartite interference network from a set of L transmitting nodes to a set of K receiving nodes with LK component channels between each pair of transmitting and receiving nodes. One may consider this network as the overlay of an interference network defined as a part of FBIN(4,4) consisting of two FBIN(2,2), one defined from the first two transmitting nodes to the first two receiving nodes, and the other defined from the last two transmitting point to the last two receiving points, with a desired network defined by the complement of this network. We can easily deduce that DoF per node of 2 is achievable for all nodes. Hence, we can remove the interference network and consider the network with only two antennas at each node and update the component channels respectively. Please note that for the generic choice of channel conditions, the channels remain generic with this update process. Now we have a network that consist of exactly two FBIN(2,2), one defined from the first two transmitting nodes to the last two receiving nodes and one from the last two transmitting points to the first two receiving nodes. Hence, it is immediate that DoF per node of one is achievable for all the nodes in this network which means that the same DoF per node is achievable for the original FBIN(4,4). Please note that although it is convenient and in some cases useful to partially or successively apply the tools of calculating DoF per node and reducing the problem dimension gradually, the partial application of DoF may result in the loss in finding the DoF for the original network. For example, in FBIN(4,4) with only N=3 antennas at each node DoF per node of 1 is achievable and with N=4 higher DOF per node is achievable. For example, it can be shown that DoF per node of 2 for two transmitting nodes and DoF per node of 1 for all other nodes are achievable for FBIN(4,4) with N=4 antennas per node. A more interesting result is that in FBIN(4,4) with N=3 antennas per node DoF per node of 1 is achievable. We consider the orientation for the edges of the network which goes from the first two transmitter with precoders V 1 , V 2 to the first two receiver with receive filters U 1 , U 2 . Then a reciprocal channel that goes from the first two receiving nodes with the precoders U 1 , U 2 (receive filters in the original direction) to the last two transmitting nodes with the receive filters V 3 , V 4 (that are the precoders in the original directions). Next, the channel from the last two transmitting nodes with precoders V 3 , V 4 to the last two receiving nodes with the receive filters U 3 ,U 4 and finally the reciprocal channel from the last two receiving nodes with precoders U 3 ,U 4 to the first two transmitting nodes with precoders V 1 , V 2 . Then, 1. U j =H ji V i ×H j2 V 2 , if 1≦j≦2; 2. U j =H ji V 3 ×H j4 V 4 , if 3≦j≦4; 3. V i =H 1i *U 1 ×H 2i *U 2 , if 3≦i≦4; 4. V i =H 3i *U 3 ×H 4i *U 4 , if 1≦i≦2. [0026] where ‘x’ is the standard curl operation between two vectors and H* denotes the channel reciprocal to channel H. For example the conditions (i) states that the space represented by U j is a one dimensional space that is orthogonal to the two dimensional space defined by the vectors H ji V 1 and H j2 V 2 , etc. [0027] Putting together, we get 1. V i =H 1i *(H 11 V 1 ×H 12 V 2 )×H 2i *(H 21 V 1 ×H 22 V 2 ), if 3≦i≦4; 2. V i =H 3i *(H 33 V 3 ×H 34 V 4 )×H 4i *(H 43 V 3 ×H 44 V 4 ), if 1≦i≦2. [0030] We can simplify this further and get an equation only involving V 1 and V 2 which can be directly solved. Then, we find U 1 , U 2 from (i), V 3 , V 4 from (iii), and finally U 3 , U 4 from (ii). This is a direct construction of one dimensional precoders and receive filters that satisfy the interference alignment condition and shows per node DoF 1 is achievable for all nodes. [0031] Next, a Symmetric Interference Network with Asymmetric DOF is detailed. Let us consider a 3-user interference channel with T={1,2,3}, R={4,5,6} where the node i intends to communicate with the node i+3, i.e., D={(1,4), (2,5), (3,6)} and the number of antennas at all nodes is N=3. It is known that the DoF equal to 1 for all three links in D is achievable. Here we argue that one can achieve total DoF of 4 over all three links. let us consider the partial interference network defined by I′={(1,5), (1,6), (2,6), (3,5)}⊂I=T×R−D. We argue that the vector d =(2,2,2,3,1,1) DoF per node is achievable in this interference network. Consider an arbitrary precoder V 1 of size 3×2 which defines a two dimensional space as an input to either of the channels from node 1 to nodes 5 and 6 . Since N=3 at each of the nodes 5 and 6 there is at least one vector (channels are generic) that is orthogonal to the received signal from node 1 based on which We define the receive filters U 5 and U 6 as a 1×3 dimensional vector. Now consider the input to the node 2 that lies in a 3 dimensional space. This input should avoid generating an output at the node 6 that corresponds to the vector defined by U 6 . So for generic choices of the channels there is a two dimensional space defined for example by the basis corresponding to the columns of V 2 that does not produce any vector corresponding to U 6 at the node 6 . Similar arguments holds for the node 3 by considering the only interfering link out of this node that goes to node 5 . [0032] Next, we can consider the rest of the interfering network by omitting the links I and replacing the number of antennas at the nodes 1 , 2 , . . . 6 by the corresponding DoF per nodes, i.e., 2, 2, 2, 3, 1, 1, respectively. We note that the interfering network in this case consists of only two links I″=I−I′={(2,4), (3,4)}. Considering the fact that the modified number of antennas at the node 2 , 3 , and 4 , are equal to 2, 2, and 3, it is simple to see that DoF per node of 1, 1, and 2 is achievable. This completes the proof of showing that DoF per node of (2,1,1,2,1,1) is achievable. [0033] Considering the desired network defined by the edges in D, it can be deduced that the DoF for each link is the minimum of per node DoF of the nodes at the two ends of this link which means for the first link DoF is equal to 2 and for the other two links the DoF is equal to one for the total of 4 DoF for all three communication links in this network. [0034] It is also possible to show a vector of (2,2,2,1,1,1) DoF per node is achievable which is an asymmetric in terms of the total transmit and receive degrees of freedom in the network. Hence, considering the desired network to be defined by the set of edges in D defined above the DoF per communication link remains to be one for all the three links. However, considering a different desired network defined by D, ={(1,7),(2,7),(3,7),(8,4),(8,5),(8,6)} with node 8 as transmitter and node 7 as receiver overlayed on top of the same interference network I it is easy to see that total DoF for the entire communication links in the network is equal to 6 in the uplink channel from nodes 1 , 2 , and 3 to node 7 and it is equal to 3 for the downlink channel from node 8 to node 4 , 5 , and 6 for the total of 9 DoF. [0035] Next an Asymmetric Interference network is discussed. Here we consider an asymmetric interference network with three transmitters T={1,2,3} and four receivers R={4,5,6,6} and all the interchannels between every transmitter to the receiver. This channel is reciprocal to the channel depicted in FIG. 1( b ). We assume that all nodes have 3 antennas. Here, we only focus on the interference network without a particular desired network and we would like to find an achievable DoF per node for this interference network. first let us define a partial interference network that consist of the edges between the first 6 nodes of the network and does not include the edges r={(1,7), (2,7), (3,7)}. It was seen that DoF per nodes of (2,2,2,1,1,1) is available for the nodes 1 to 6 and since node 7 is an isolated node in this partial interference network without connection to any other node it is immediate that the vector of achievable DoF per node in the partial interference network is (2,2,2,1,1,1,3). Now, by reducing the interference network to a network with (2,2,2,1,1,1,3) antennas per nodes 1 to 7 and with the edges defined by I′ we can see that the problem reduces to finding DoF per node in a multiple access network with three transmitting nodes with two antenna each to a single destination with 3 antennas which is very simple to see that DoF of one per communication node is possible. Hence DoF of 1 for the original network with three transmit and four receive antennas with channels connecting every pair of transmit and receive nodes is achievable. [0036] The Interference Network can be Overlayed with MAC and BC. FIG. 2 shows an example of a communication network divided into an interference network overlayed with a desired communication network comprising of a MAC, a BC, and a single link. Consider a communication network depicted in FIG. 2 consisting of 4 transmitting nodes labeled as 1 , 3 , 5 , and 7 communicating with 4 receiving nodes labeled as 2 , 4 , 6 , and 8 that are located in a area and border of a disk. The communication channel between a pair of transmitter and receiver is assumed to be independent fading (satisfying generic channel condition) with the average channel gain based on the distance between the node. The nodes consider to be out of the interference range if the distance between the nodes is larger than, e.g., ¾ of the diameter of the disk. Hence, for the network topology depicted in FIG. 2 the nodes 4 , 6 , and 8 are out of the range to receive an interference from the nodes 7 , 3 , and 5 , respectively. We define the desired communication network as a combination of (i) a broadcast channel (BC) from node 1 to nodes 4 and 6 , (ii) a multiple access channel (MAC) from the nodes 5 and 7 to node 2 , and (iii) a single link channel from node 3 to node 8 . The communication received from a transmitting link in all other links beside the ones in the desired communication network is considered to be interference and the corresponding link define the interference network that consist of the links (1,2), (3,2), (3,4), (5,4), (5,6), (7,6), (7,8), and (1,8). Assume that each nodes has 4 antennas. The nodes can achieve DoF per node of 2 in this interference network. The solution can be obtained as follows. The precoders V 1 , V 3 , V 5 , V 7 must satisfy the following equations where [0000] s _ _ [0000] means that the vector spaces defined by the column of the matrices in the left and right of this operator have to be the same (have same span). [0000] H 21  V 1 S = H 23  V 3 ( 4 ) H 43  V 3 S = H 45  V 5 ( 5 ) H 65  V 5 S = H 67  V 7 ( 6 ) H 87  V 7 S = H 81  V 1 ( 7 ) [0037] Hence, it is enough to have [0000] V 1 S = H 21 - 1  H 23  H 43 - 1  H 45  H 65 - 1  H 67  H 87 - 1  H 81  V 1 = H c  V 1 ( 8 ) [0038] which means that the columns of V 1 should be the eigenvectors of the matrix H c . Hence, we can simply pick any two eigenvectors of the matrix H c to form the precoding matrix V 1 . The precoders V 3 , V 5 , and V 7 are then obtained successively based on the above equations. Finding the receive filters are also very easy once the transmit precoders are fixed. The above construction does not limits the number of eigenvectors that can be picked, however, the space of the receive filters would decrease as we increase the size of the space of the precoders. For example by picking 3 eigenvectors to form V 1 , the other precoder also would be equivalent to a 3-dimensional subspace which then limits each of the receive filter to lie in a 1-dimensional space which translates to the achievable vector of DoF per node (3,1,3,1,3,1,3,1). [0039] Having DoF per node of 2 for all nodes, we can now eliminate the interference network and focus on the desired communication network. For example an interesting observation here could be the fact that in the MAC channel part of this network, no more than two streams can be decoded, but it is possible to use precoders at the transmitting nodes to optimize the rate. We note that the design of the precoders depends on the updated channels from the nodes 5 and 7 to node 2 which is composed of two 2×2 channels. [0040] A Full Bipartite Interference Network (FBIN) is detailed next. In this section we address an example of interference networks that is practically useful in cellular networks where FD access points are employed. Recent results on the development of the practical techniques to enable full duplex shows that the use of single band full duplex communication systems in order to potentially double the spectral efficiency is one of the major research topics in the future of our wireless communications. Although several implementation of the single link full duplex (FD) systems has been reported in the past few years one of the major limiting factor in the deployment and further development of these systems has been identified as the limitation of having mixture of uplink and downlink users in a single cell that are working in the same band. In particular even though a well designed and sophisticated approach can be used at the basestations or access points (APs), an uplink user generates an interference in nearby downlink clients that are working in the same band. Hence, until the problem of uplink interference on downlink users is not properly addressed, the potential doubling of spectral efficiency is not possible in multi-user systems and particularly in single cell wireless communication systems. [0041] As a part of our contribution, we use concept of ‘DoF per communication node’ to provide results on single cell equipped with full duplex access points. In contrast to the prior results on limited performance of using FD in single cell, we provide a very optimistic results that shows the doubling of spectral efficiency is still possible by using FD access points in comparison to half duplex (HD) access points with proper design of interference alignment scheme. We further show that a simple selection of four users, two in the uplink and two in the downlink, may suffice to achieve the full potential of the full duplex system. This simple example has a very important practical consideration in which the overhead of implementing the interference alignment and calculation of precoders and receiver filters is considered. It goes without saying that increasing the number of channels that need to be estimated and fed back as well as the forward signaling of the precoders and receive filters within the coherence time of the channel could be a very important practical consideration and hence limiting the number of users required to theoretically attain the full benefit of a FD AP is an important factor. [0042] Interference alignment in FBIN is handled next. FIG. 3 shows a Single Cell Channel: consists of FBIN and a desired network comprising of a MAC and a BC. For practical reason, we focus on the interference alignment in space domain where the channel coefficients are fixed. We consider a fixed precoder per block or multiple block of transmission within the channel coherence time where the channel coefficients are approximately constant. As shown in FIG. 3( a ), we consider a FBIN(L,K) with L transmitting nodes labeled as (i,t)εT, i=1, . . . , L and K receiving nodes labeled as (j,r)εR where subindexes t and r denote the transmitting and receiving nodes, respectively. we consider transmit precoding matrix V i , i=1, 2, . . . , L at each transmission node and a receiver filter or a receive precoding matrix U j , j=1, 2, . . . , K at each receiving node. The transmit precoding matrices V i are of dimension N t,i ×d t,i where d t,i ≦N t,i and receive filters U 1 are of dimension d r,j ×N r,j where d r,j ≦N r,j . The alignment conditions are given by [0000] U i H ij V j =0 ∀ i= 1,2, . . . , L , and j= 1,2, . . . , K   (9) [0043] where H ji εI denotes the component channels of the interference network from node i to node j. We note that the alignment conditions may be written in terms of rows of U i =[u i 1 u i 2 . . . u i d r,i ] T and the columns of V j =[v i 1 v i 2 . . . v i d r,i ]. This means that all vectors u i a and v j b for a given i and j and for all indices a and b satisfy similar equations [0000] u i a H ij v j b =0  (10) [0044] This condition reveals two necessary conditions immediately. First, the degrees of freedom of a receiving node j that is the number of independent vectors v j b , cannot be more than the dimension of the vector space that contains this vector, hence d t,j ≦Nt,j. Similarly, for u i a we have d r,i ≦Nr,i that is the second necessary condition. There are two more conditions that can be deduced from (10). The third necessary condition is given by d r,i +d t,j ≦max N r,i ,N t,j . This is true due to the fact that if N r,i ≦N t,j for a given i and j all vectors H ij v j b have to be linearly independent since H ij is generic and furthermore they are orthogonal to all u i a which means that the total number of such vectors are less than the dimension of the vector u i a that is N r,i . [0045] The fourth necessary condition may be obtained by counting the number of scalar variables and scalar equations or constraint that the variable have to satisfy. The intuition obtained from the linear algebra is that a system of linear equation most likely does not have a solution if the number of variables are less than the number of constraint is the coefficients of the equations are generic. Although the formulation based on the DoF per node is slightly different, this counting argument for DoF in classical interference channel has been presented by several prior work and has been shown to be a necessary condition. The number of variables in a subset of equations S between the transmit and receiving node pair j) is given by Σ l:(i,j)εs d t,i (N t,l −d t,i )+Σ j:(i,j)εs d t,i (N r,i −d r,i ) where [0000] S ⊂ M ={( i,j ),1≦ i≦L, 1≦ j≦K}   (11) [0046] On the other hand, the number of scalar equation in the same set S is given by Σ i,j:(i,j)εs d t,i d r,j . Therefore the fourth necessary condition is given by [0000] ∑ i : ( i , j ) ∈ S   d t , i  ( N t , i - d t , i ) + ∑ j : ( i , j ) ∈ S   d r , i  ( N r , i - d r , i ) ≥ ∑ i , j : ( i , j ) ∈ S   d t , i  d r , j   ∀ S ⊆ M ( 12 ) [0047] The DoF per node for FBIN is discussed next. Let us consider a single cell wireless communication network with an access point (AP) indexed as node 0 and collection of L uplink and K downlink users where the desired network consists of (i) a multiple access channel from all uplink nodes to the AP and (ii) a broadcast channel from the AP to all downlink nodes. The interference network consists of all the channels between the uplink and downlink users that can be modeled as a FBIN(L, K). [0048] First, we note that in this model with a FD AP with N transmit and N receive RF chains the total DoF is given by [0000] DoF FD = min ( N , ∑ i = 1 L   d t , i ) + min ( N , ∑ i = 1 K   d r , i ) ( 13 ) [0049] where and d t,i , i=1, . . . , K, and d r,i , i=1, . . . , K are the per node DoF at the transmitting and receiving nodes, respectively. The proof relies on the fact that (i) by removing the FBIN and replacing the number of antennas at each node with its per node DoF we are only left with the desired network that consists of two separate MAC and BC, and (2) the DoF for a MAC or BC is the minimum of the number of antennas at the AP and the sum of DoF of its users. On the other hand if the AP is only HD with N antennas, then the total DoF can be found for either uplink (UL) or downlink (DL) as [0000] DoF HD , UL = min ( N , ∑ i = 1 L   d t , i ) , ( 14 ) DoF HD , DL = min ( N , ∑ i = 1 K   d r , i ) , ( 15 ) [0050] respectively. [0051] second, we show that in a FBIN(2,2) channel ( FIG. 3( b )) with N antenna at each node DoF per node equal to d,d≦N for all uplink users and N−d for all downlink users is simultaneously achievable. Let V 1 and V 2 be the transmit precoder of size N×d and U 1 and U 2 be the receive filters of size N×(N−d). The following has to be satisfied. [0000] U i H ij V j =0 ∀ i= 1,2, and j= 1,2  (16) [0052] We select V 1 and V 2 such that [0000] ( H 11  V 1 ) S = H 12  V 2 [0000] in order to align the interferences of both transmitting nodes into the same space of size N×d dimensions at the receiving node (l,r). Such selection is easy as for any choice of the precoding matrix V 1 , the precoding matrix V 2 can be obtained by choosing V 2 =H 12 −1 H 11 V 1 where for random matrices H ij this can be done with probability 1. In order to align the interferences of both transmitter to the receiving node 2 , we must have H 21 V 1 S =H 22 V 2 , hence it is enough to have V 1 S =H 21 −1 H 22 H 12 −1 H 11 V 1 ). This means that can be composed of any d eigenvectors of the matrix H 21 −1 H 22 H 12 −1 H 11 and V 2 =H 12 −1 H 11 V 1 . Under these conditions the space of signals at both receiving nodes is limited to a d dimensions and hence there exist N−d orthogonal dimensions at each receiving nodes which is used to construct N×(N−d) dimensional receive filters U 1 and U 2 . [0053] While the above argument shows that the total sum of per node DoF in a FBIN(2,2) with N antennas at each node can be equal to 2N the following argument shows that in fact this is the maximum value that this sum can take. Let d t,i and d r,i , i=1,2 denote the degrees of freedom of transmitting nodes and receiving nodes, respectively. Using the counting argument (??), we have [0000] ∑ i = 1 2   d t , i  ( N - d t , i ) + d r , i  ( N - d r , i ) ≥ ∑ i = 1 2   ∑ i = 1 2   d t , i  d r , j ( 17 ) [0054] Rearranging the above inequality, the following should hold [0000] ( d t , 1 + d t , 2 + d r , 1 + d r , 2 )  N ≥ ∑ i = 1 2   d t , i 2 + ∑ i = 1 2   d r , i 2 + ∑ i = 1 2   ∑ i = 1 2   d t , i  d r , j ( 18 ) ≥ ∑ i = 1 2   d t , i 2 + ∑ i = 1 2   d r , i 2 + ∑ i = 1 2   ∑ i = 1 2   d t , i  d r , j - ( d t , 1 - d t , 2 ) 2 - ( d r , 1 - d r , 2 ) 2 ( 19 )  ≥ 1 2  ( d t , 1 + d t , 2 + d r , 1 + d r , 2 ) 2 ( 20 ) [0055] Hence, we have [0000] ( d t,1 +d t,2 +d r,1 +d r,2 )≦2 N   (21) [0056] Comparing a the total number of streams that can be simultaneously transmitted in a single cell with FD versus HD AP, one can conclude that it is possible to achieve twice the number of streams with FD AP for a total of 2N streams versus only N streams with HD AP (when N is an even number). Furthermore, to achieve this spectral efficiency gain it is enough to select only two uplink and two downlink users. This is a very optimistic results which shows that using an interference alignment can restore the promised doubling gain of using FD versus HD radios in a multi-user communication systems such as a single cell wireless systems. [0057] The maximum sum of the per node DOF in a FBIN(K, K) channel with a symmetric d DoF per node and N antenna at each node is [0000] 2  K  ⌊ 2  N K + 2 ⌋ . [0000] We use the counting argument that is a necessary condition. We have [0000] 2  N K + 2 [0058] we have 2K nodes each with degrees of freedom less than or equal to [0000] 2  N K + 2 [0000] that will add up to [0000] 2  K  ⌊ 2  N K + 2 ⌋ . [0000] This means that for large enough K this total sum tends to 4N. Although the construction of a solution to achieve this bound is beyond the scope of this paper, this bound is in fact achievable. The implication of this result is as follows. Consider two adjacent cells where the access points have complete cooperation (e.g. using joint transmission in practical systems that are enabled with cooperative multipoint transmission (CoMP)). The two APs have complete cooperation hence there is no interference between them and furthermore they can use network MIMO which means they can be viewed as a virtual AP with 2N antennas. The uplink users may generate interference to the downlink users in their own cell as well as the adjacent cells. Considering the set of all uplink users and downlink users, the interference network is a FBIN in which total sum of 4N per node DoF is achievable. Hence two FD APs can simultaneously serve 4N streams while replacing them with two HD APs we can only serve 2N streams. Of course this result is asymptotic and requires large number of users to be selected that are properly split between the cells as well as uplink and downlink. Nonetheless, it is very interesting to observe that even in multi-cell systems (2-cells) the promised doubling of the spectral efficiency might still be achievable, at least in theory. Since this topic is out of the scope of this paper we do not make further discussion and just point out that this scaling will slow down for larger number of cells and would not remain as a factor of two when the number of cells are more than two. [0059] In sum, the system handles degrees of freedom (DoF) in the network. Classically DoF is defined for collection of independent links in the network. In contrast we introduce DoF per nodes. Furthermore, we introduce the technique of dividing a network into an interference network and a desired communication network, where the former consists of the links over which the actual data transmission is performed and the latter consists of the link that do not carry information and only cause interference to their corresponding receivers. We tied back our definition of per node DoF to the classical concept of DoF and further showed its usefulness in several new areas and problems, including simpler interpretation of DoF, separation of dealing with interference in the network from communication in the desired network, successive application of interference removal by applying the technique over partial interference network, and considering several new scenarios of interference alignment problem particularly in the form of full bipartite interference network. [0060] The problem of interference alignment in FBIN has particular importance in the context of cellular networks and dealing with interference in single or multiple cells especially when full duplex radios are possible to use. As we discussed the scalability of throughput in a wireless systems with multiple cells requires tight coordination between the access point. However, recent work have shown that global coordination and information exchange is not in fact necessary due to the fact that the interference is usually strong in a local vicinity and would not spread in the network globally. Therefore huge complexity and overhead of the global information exchange and the exhaustive burden of implementing a tight coordination between all access points can be replaced by coordination between neighboring cells that is much more manageable. We note that similar local coordination might be enough for the purpose of interference alignment particularly when full duplex access points are deployed. [0061] The use of full duplex in cellular systems can be done by characterizing the gain of using full duplex access point versus using half duplex access point. By exchanging HD APs to FD Aps, a doubling of the spectral efficiency is possible in single cell or 2-cell network with full cooperation between their access points. [0062] The invention may be implemented in hardware, firmware or software, or a combination of the three. Preferably the invention is implemented in a computer program executed on a programmable computer having a processor, a data storage system, volatile and non-volatile memory and/or storage elements, at least one input device and at least one output device. [0063] Each computer program is tangibly stored in a machine-readable storage media or device (e.g., program memory or magnetic disk) readable by a general or special purpose programmable computer, for configuring and controlling operation of a computer when the storage media or device is read by the computer to perform the procedures described herein. The inventive system may also be considered to be embodied in a computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein. [0064] The invention has been described herein in considerable detail in order to comply with the patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself.

Systems and methods are disclosed to operate a communication network by dividing signal dimensions at a receiver into interference and intended signal dimensions; applying transmit precoding to mitigate interference by overlapping the interference from a plurality of transmitters into the interference dimension at thea receiver; and applying a receiver filter to cancel out the interference dimension at the receiver and recover the signal in the intended signal dimension.

This application is a division of U.S. patent application Ser. No. 08/282,964, filed Jul. 29, 1994 which is in turn a division of U.S. patent application Ser. No. 08/015,083 filed Feb. 8, 1993, now U.S. Pat. No. 5,362,720 which is in turn a continuation of U.S. patent application Ser. No. 07/724,532 filed Jun. 28, 1991, now abandoned. BACKGROUND OF THE INVENTION This invention relates to a method for treating or preventing breast and endometrial cancer, bone loss, and for treating endometriosis in susceptible warm-blooded animals including humans involving administration of a compound possessing androgenic activity, and to kits containing active ingredients to be used in the therapy. Various investigators have been studying hormonal therapy for breast and endometrial cancer as well as for the prevention and treatment of bone loss and for treatment of endometriosis. The main approaches for the treatment of already developed breast cancer are related to the inhibition of estrogen action and/or formation. The role of estrogens in promoting the growth of estrogen-sensitive breast cancer is well recognized (Lippman, Semin. Oncol. 10 (suppl. 4): 11-19, 1983; Sledge and McGuire, Cancer Res. 38:61-75, 1984; Wittliff, Cancer 53:630-643, 1984; Poulin and Labrie, Cancer Res. 46:4933-4937, 1986). Estrogens are also known to promote the proliferation of normal endometrium. Chronic exposure to estrogens unopposed by progesterone can lead to the development of endometrial hyperplasia which predisposes to endometrial carcinoma (Lucas, Obstet. Gynecol. Surv. 29:507-528, 1974). The incidence of endometrial cancer increases after menopause, especially in women receiving estrogen therapy without simultaneous treatment with progestins (Smith et al., N. Engl. J. Med. 293:1164-1167, 1975; Mack et al., N. Engl. J. Med. 294:1262-1267, 1976). Various investigators have been studying hormone-dependent breast and endometrial cancer. A known form of endocrine therapy in premenopausal women is castration most commonly performed by surgery or irradiation, two procedures giving irreversible castration. Recently, a reversible form of castration has been achieved by utilizing Luteinizing Hormone-Releasing Hormone Agonists (LHRH agonists) which, following inhibition of secretion of bioactive Luteinizing Hormone (LH) by the pituitary gland, decrease serum estrogens to castrated levels (Nicholson et al., Brit. J. Cancer 39:268-273, 1979). Several studies show that treatment of premenopausal breast cancer patients with LHRH agonists induces responses comparable to those achieved with other forms of castration (Klijn et al., J. Steroid Biochem. 20:1381, 1984; Manni et al., Endocr. Rev. 7:89-94, 1986). Beneficial effects of treatment with LHRH agonists have also been observed in postmenopausal women (Nicholson et al., J. Steroid Biochem. 23:843-848, 1985). U.S. Pat. No. 4,071,622 relates to the use of certain LHRH agonists against DMBA-induced mammary carcinoma in rats. U.S. Pat. No. 4,775,660 relates to the treatment of female breast cancer by use of a combination therapy comprising administering an antiandrogen and an antiestrogen to a female after the hormone output of her ovaries has been blocked by chemical or surgical means. U.S. Pat. No. 4,775,661 relates to the treatment of female breast cancer by use of a therapy comprising administering to a female, after the hormone output of her ovaries has been blocked by chemical or surgical means, an antiandrogen and optionally certain inhibitors of sex steroid biosynthesis. U.S. Pat. No. 4,760,053 describes a treatment of selected sex steroid dependent cancers which includes various specified combinations of compounds selected from LHRH agonists, antiandrogens, antiestrogens and certain inhibitors of sex steroid biosynthesis. In U.S. Pat. No. 4,472,382 relates to treatment of prostatic adenocarcinoma, benign prostatic hypertrophy and hormone-dependent mammary tumors with specified pharmaceuticals or combinations. Various LHRH agonists and antiandrogens are discussed. International Patent Application PCT/W086/01105, discloses a method of treating sex steroid dependent cancers in warm-blooded animals which comprises administering specific pharmaceuticals and combinations. Antiandrogens, antiestrogens, certain inhibitors of sex steroid biosynthesis and blocking of hormonal output are discussed. The inventor's co-pending U.S. patent application No. 07/321926 filed Mar. 10, 1989, relates to a method of treatment of breast and endometrial cancer in susceptible warm-blooded animals which may include inhibition of ovarian hormonal secretion by surgical means (ovariectomy) or chemical means (use of an LHRH agonist, e.g. [D-Trp 6 , des-Gly-NH 2 10 ]LHRH ethylamide, or antagonists) as part of a combination therapy. Antiestrogens, androgens, progestins, inhibitors of sex steroid formation (especially of 17β-hydroxysteroid dehydrogenase- or aromatase-catalyzed production of sex steroids), inhibitors of prolactin secretion and of growth hormone secretion and ACTH secretion are discussed. Androgen receptors have been shown to be present in normal (Witliff, In: Bush, H. (Ed.), Methods in Cancer Res., Vol. 11, Acad. Press, New York, 1975, pp. 298-304; Allegra et al., Cancer Res. 39:1447-1454, 1979) and neoplastic (Allegra et al., Cancer Res. 39:1147-1454, 1979; Engelsman et al., Brit. J. Cancer 30:177-181, 1975; Moss et al., J. Ster. Biochem. 6:743-749, 1975; Miller et al., Eur. J. Cancer Clin. Oncol. 2:539-542, 1985; Lippman et al., Cancer 38:868-874, 1976; Allegra et al., Cancer Res. 39:1447-1454, 1979; Miller et al., Eur. J. Clin. Oncol. 21:539-542, 1985; Lea et al., Cancer Res. 49:7162-7167, 1989) as well as in several established breast cancer cell lines (Lippman et al., Cancer Res. 36:4610-4618, 1976; Horwitz et al., Cancer Res. 38:2434-2439, 1978; Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988). Androgen receptors are also present in dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in the rat (Asselin et al., Cancer Res. 40:1612-1622, 1980). Androgen receptors have also been described in human endometrium (MacLaughlin and Richardson, J. Steroid Biochem. 10:371-377, 1979; Muechler and Kohler, Gynecol. Invest. 8:104, 1988). The growth inhibitory effects of the androgen methyltrienolone (R1881), on endometrial carcinoma in vitro have been described (Centola, Cancer Res. 45:6264-6267, 1985). Recent reports have indicated that androgen receptors may add to the selective power of estrogen receptors or even supplant estrogen receptors as best predicting response to endocrine therapy (Teulings et al., Cancer Res. 40:2557-2561, 1980; Bryan et al., Cancer 54:2436-2440, 1984). The first androgen successfully used in the treatment of advanced breast cancer is testosterone propionate (Nathanson, Rec. Prog. Horm. Res. 1:261-291, 1947). Many studies subsequently confirmed the beneficial effect of androgens on breast cancer (Alan and Herrman, Ann. Surg. 123:1023-1035; Adair, Surg. Gynecol. Obstet. 84:719-722, 1947; Adair et al., JAMA 140:1193-2000, 1949). These initial results stimulated cooperative studies on the effect of testosterone propionate and DES which were both found to be effective in producing objective remissions. (Subcommittee on Steroid and Cancer of the Committee on Research of the Council on Pharmacy and Chemistry of the Am. Med. Association followed by the Cooperative Breast Cancer Group under the Cancer Chemotherapy National Service Center of the NCI who found that testosterone propionate improved remission rate and duration, quality of life and survival (Cooperative Breast Cancer Group, JAMA 188, 1069-1072, 1964)). A response rate of 48% (13 of 27 patients) was observed in postmenopausal women who received the long-acting androgen methonolone enanthate (Kennedy et al., Cancer 21:197-201, 1967). The median duration of survival was four times longer in the responders as compared to the non-responder group (27 versus 7.5 months). A large number of studies have demonstrated that androgens induce remission in 20 to 40% of women with metastatic breast cancer (Kennedy, Hormone Therapy in Cancer. Geriatrics 25:106-112, 1970; Goldenberg et al., JAMA 223:1267-1268, 1973). A response rate of 39% with an average duration of 11 months has recently been observed in a group of 33 postmenopausal women who previously failed or did not respond to Tamoxifen (Manni et al., Cancer 48:2507-2509, 1981) upon treatment with Fluoxymesterone (Halostatin) (10 mg, b.i.d.). Of these women, 17 had also undergone hypophysectomy. There was no difference in the response rate to Fluoxymesterone in patients who had previously responded to Tamoxifen and in those who had failed. Of the 17 patients who had failed to both Tamoxifen and hypophysectomy, 7 responded to Fluoxymesterone for an average duration of 10 months. Among these, two had not responded to either Tamoxifen or hypophysectomy. The combination Fluoxymesterone and Tamoxifen has been shown to be superior to Tamoxifen alone. In fact, complete responses (CR) were seen only in the combination arm while 32% showed partial response (PR) in the combination arm versus only 15% in the monotherapy arm. In addition, there were only 25% of non-responders in the combination therapy arm versus 50% in the patients who received TAM alone (Tormey et al., Ann. Int. Med. 98:139-144, 1983). Moreover, the median time from onset of therapy to treatment failure was longer with Fluoxymesterone+Tamoxifen (180 days) compared to the Tamoxifen arm alone (64 days). There was a tendency for improved survival in the combination therapy arm (380 versus 330 days). The independent beneficial effect of an androgen combined with an antiestrogen is suggested by the report that patients who did not respond to Tamoxifen could respond to Fluoxymesterone and vice versa. Moreover, patients treated with Tamoxifen and crossing over to Fluoxymesterone survived longer that those treated with the reverse regimen (Tormey et al., Ann. Int. Med. 98:139-144, 1983). Since testosterone propionate had beneficial effects in both pre- and post-menopausal women (Adair et al., J. Am. Med. Ass. 15:1193-1200, 1949), it indicates that in addition to inhibiting gonadotropin secretion, the androgen exerts a direct inhibitory effect on cancer growth. Recent in vitro studies describe the relative antiproliferative activities of an androgen on the growth of the estrogen-sensitive human mammary carcinoma cell line ZR-75-1 (Poulin et al. "Androgens inhibit basal and estrogen-induced cell proliferation in the ZR-75-1 human breast cancer cell line", Breast Cancer Res. Treatm. 12:213-225, 1989). As mentioned above, Poulin et al. (Breast Cancer Res. Treatm. 12:213-225, 1989) have found that the growth of ZR-75-1 human breast carcinoma cells is inhibited by androgens, the inhibitory effect of androgens being additive to that of an antiestrogen. The inhibitory effect of androgens on the growth of human breast carcinoma cells ZR-75-1 has also been observed in vivo in nude mice (Dauvois and Labrie, Cancer Res. 51:3131-3151, 1991). As a possible mechanism of androgen action in breast cancer, it has recently been shown that androgens strongly suppress estrogen (ER) and progesterone (PgR) receptor contents in ZR-75-1 human breast cancer cells as measured by radioligand binding and anti-ER monodonal antibodies. Similar inhibitory effects were observed on the levels of ER mRNA measured by ribonuclease protection assay. The androgenic effect is measured at subnanomolar concentrations of the non-aromatizable androgen 5-α-dihydrotestosterone, regardless of the presence of estrogens, and is competitively reversed by the antiandrogen hydroxyflutamide (Poulin et al., Endocrinology 125:392-399, 1989). Such data on estrogen receptor expression provide an explanation for at least part of the antiestrogenic effects of androgens on breast cancer cell growth and moreover suggest that the specific inhibitory effects of androgen therapy could be additive to the standard treatment limited to blockade of estrogens by antiestrogens. Dauvois et al. (Breast Cancer Res. Treatm. 14:299-306, 1989) have shown that constant release of the androgen 5α-dihydrotestosterone (DHT) in ovariectomized rats bearing DMBA-induced mammary carcinoma caused a marked inhibition of tumor growth induced by 17β-estradiol (E 2 ). That DHT acts through interaction with the androgen receptor is supported by the finding that simultaneous treatment with the antiandrogen Flutamide completely prevented DHT action. Particularly illustrative of the potent inhibitory effect of the androgen DHT on tumor growth are the decrease by DHT of the number of progressing tumors from 69.2% to 29.2% in E 2 -treated animals and the increase by the androgen of the number of complete responses (disappearance of palpable tumors) from 11.5% to 33.3% in the same groups of animals. The number of new tumors appearing during the 28-day observation period in E 2 -treated animals decreased from 1.5±0.3 to 0.7±0.2 per rat during treatment with the androgen DHT, an effect which was also reversed by the antiandrogen Flutamide. Such data demonstrate, for the first time, that androgens are potent inhibitors of DMBA-induced mammary carcinoma growth by an action independent from inhibition of gonadotropin secretion and suggest an action exerted directly at the tumor level, thus further supporting the in vitro data obtained with human ZR-75-1 breast cancer cells (Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988). The natural androgens testosterone (TESTO) and dihydrotestosterone (DHT) are formed from conversion of androstenedione into TESTO by 17β-hydroxysteroid dehydrogenase and then TESTO into DHT by the action of the enzyme 5α-reductase. The adrenal precursor 5-androst-5-ene-3β,17β-diol can also be converted into TESTO by action of the enzyme 3β-hydroxysteroid dehydrogenase/Δ 5 Δ 4 isomerase (3β-HSD). Since the natural androgens TESTO and DHT have strong masculinizing effects, numerous derivatives of TESTO as well as progesterone have been synthesized in order to obtain useful compounds having fewer undesirable masculinizing side effects (body hair growth, loss of scalp hair, acne, seborrhea and loud voice). Medroxyprogesterone acetate (MPA) is one of the most widely used compounds in the endocrine therapy of advanced breast cancer in women (Mattsson, Breast Cancer Res. Treatm. 3:231-235, 1983; Blumenschein, Semin. Oncol. 10:7-10, 1983; Hortobagyi et al., Breast Cancer Res. Treatm. 5:321-326, 1985; Haller and Glick, Semin. Oncol. 13:2-8, 1986; Horwitz, J. Steroid Biochem. 27:447-457, 1987). The overall clinical response rate of high doses of this synthetic progestin averages 40% in unselected breast cancer patients (Horwitz, J. Steroid Biochem. 27:447-457, 1987), an efficacy comparable to that of the non-steroidal antiestrogen tamoxifen (Lippman, Semin. Oncol. 10 (Suppl.): 11-19, 1983). Its more general use, however, is for breast cancer relapsing after other endocrine therapeutic modalities. The maximal inhibitory action of medroxyprogesterone acetate (MPA) on human breast cancer cell growth in vitro may be achieved at concentration as low as 1 nM while an approximately 1000-fold higher dose is often required for glucocorticoid action (Poulin et al., Breast Cancer Res. Treatm. 13:161-172, 1989). Until recently, the mechanisms underlying the antitumor activity of MPA were poorly understood and have been attributed to interaction with the progesterone receptor. This steroid, however, presents a high affinity for progesterone (PgR) as well as for androgen (AR) and glucocorticoid receptors (GR) in various animal tissues (Perez-Palacios et al., J. Steroid Biochem. 19:1729-1735, 1983; Janne and Bardin, Pharmacol. Rev. 36:35S-42S, 1984; Pridjian et al., J. Steroid Biochem. 26:313-319, 1987; Ojasso et al., J. Steroid Biochem. 27:255-269, 1987) as well as in human mammary tumors (Young et al., Am. J. Obstet. Gynecol. 137:284-292, 1980), a property shared with other synthetic progesterone derivatives (Bullock et al., Endocrinology 103:1768-1782, 1978; Janne and Bardin, Pharmacol. Rev. 36:35S-42S, 1984; Ojasso et al., J. Steroid Biochem. 27:255-269, 1987). It is known that in addition to progesterone receptors (PgR), most synthetic progestational agents bind with significant affinity to androgen (AR) as well as glucocorticoid (GR) receptors, and induce biological actions specifically determined by these individual receptor systems (Labrie et al., Fertil. Steril. 28:1104-1112, 1977; Engel et al., Cancer Res. 38:3352-3364, 1978; Raynaud et al., In: Mechanisms of Steroid Action (G. P. Lewis, M. Grisburg, eds), MacMiland Press, London, pp. 145-158, 1981; Rochefort and Chalbos, Mol. Cell. Endocrinol. 36:3-10, 1984; J anne and Bardin, Pharmacol. Rev. 36:35S-42S, 1984; Poyet and Labrie, Mol. Cell. Endocrinol. 42:283-288, 1985; Poulin et al., Breast Cancer Res. Treatm. 13:161-172, 1989). Accordingly, several side effects other than progestational have been noted in patients treated with MPA. The most easily explained adverse side effects of MPA are related to its glucocorticoid-like action with Cushingoid syndrome, euphoria and subjective pain relief (Mattsson, Breast Cancer Res. Treatm. 3:231-235, 1983; Blossey et al., Cancer 54:1208-1215, 1984; Hortobagyi et al., Breast Cancer Res. Treatm. 5:321-326, 1985; Van Veelen et al., Cancer Chemother. Pharmacol. 15:167-170, 1985). Suppression of adrenal function by MPA is believed to be caused both by an inhibitory action on ACTH secretion at the pituitary level and by direct inhibition of steroidogenesis at the adrenal level (Blossey et al., Cancer 54:1208-1215, 1984; Van Veelen et al., Cancer Chemother. Pharmacol. 15:167-170, 1985; Van Veelen et al., Cancer Treat. Rep. 69:977-983, 1985). Despite its high affinity for AR, MPA seldom causes significant virilizing symptoms (acne, hirsutism, etc.) (Hailer and Glick, Semin. Oncol. 13:2-8, 1986). Moreover, its inhibitory effect on gonadotropin secretion is clearly exerted through its direct interaction with pituitary AR in the rat (Labrie et al., Fertil. Steril. 28:1104-1112, 1977; Perez-Palacios et al., J. Steroid Biochem. 19:1729-1735, 1983) and human (Perez-Palacios et al., J. Steroid Biochem. 15:125-130, 1981). In addition, MPA exhibits androgenic activity in the mouse kidney (J anne and Bardin, Pharmacol. Rev. 36:35S-42S, 1980) and in the rat ventral prostate (Labrie, C. et al., J. Steroid Biochem. 28:379-384, 1987; Labrie C. et al., Mol. Cell. Endocrinol. 68:169-179, 1990). Poulin et al. "Androgen and glucocorticoid receptor-mediated inhibition of cell proliferation by medroxyprogesterone acetate in ZR-75-1 human breast cancer cells", Breast Cancer Res. Treatm. 13:161-172, 1989) have recently found that the inhibitory effect of medroxyprogesterone acetate (MPA) on the growth of the human ZR-75-1 breast cancer cells is mainly due to the androgenic properties of the compound. The androgenic properties of MPA have been demonstrated in other systems (Labrie C. et al., J. Steroid Biochem. 28:379-384, 1987; Luthy et al., J. Steroid Biochem. 31:845-852, 1988; Plante et al., J. Steroid Biochem. 31:61-64, 1988; Labrie C. et al., Mol. Cell. Endocrinol. 58:169-179, 1990). Other synthetic progestins have also been shown to possess, in addition to their progesterone-like activity, various degrees of androgenic activity (Labrie et al., Fertil. Steril. 31:29-34, 1979; Poyet and Labrie, The Prostate 9:237-246, 1986; Labrie C. et al., J. Steroid Biochem. 28:379-384, 1987; Luthy et al., J. Steroid Biochem. 31:845-852, 1988; Plante et al., J. Steroid Biochem. 31:61-64, 1989). High dose MPA as first treatment of breast cancer has shown similar effects as Tamoxifen (Van Veelen et al., Cancer 58:7-13, 1986). High dose progestins, especially medroxyprogesterone acetate and megestrol acetate have also been successfully used for the treatment of endometrial cancer (Tatman et al., Eur. J. Cancer Clin. Oncol. 25:1619-1621, 1989; Podratz et al., Obstet. Gynecol. 66:106-110, 1985; Ehrlich et al., Am. J. Obstet. Gynecol. 158:797-807, 1988). High dose MPA is being used with a success similar to that of Tamoxifen for the treatment of endometrial carcinoma (Rendina et al., Europ. J. Obstet. Gynecol. Reprod. Biol. 17:285-291, 1984). In a randomized clinical trial, high dose MPA administered for 6 months has been shown to induce resolution of the disease in 50% of the patients and a partial resolution in 13% of subjects compared to 12% and 6%, respectively, in patients who received placebo (Telimaa et al., Gynecol. Endocrinol. 1:13, 1987). The androgen methyltestosterone has been shown to relieve the symptoms of endometriosis (Hamblen, South Med. J. 50:743, 1987; Preston, Obstet, Gynecol. 2:152, 1965). Androgenic and masculinizing side effects (sometimes irreversible) are however important with potent androgenic compounds such as testosterone. In analogy with the androgen-induced decrease in estrogen receptors in human breast cancer ZR-75-1 cells (Poulin et al., Endocrinology 125:392-399, 1989), oral administration of MPA to women during the follicular phase caused a decrease in the level of estrogen binding in the endometrium (Tseng and Gurpide, J. Clin. Endocrinol. Metab. 41, 402-404, 1975). Studies in animals have shown that androgen deficiency leads to osteopenia while testosterone administration increases the overall quantity of bone (Silberberg and Silberberg, 1971; see Finkelstein et al., Ann. Int. Med. 106:354-361, 1987). Orchiectomy in rats can cause osteoporosis detectable within 2 months (Winks and Felts, Calcif. Tissue Res. 32:77-82, 1980; Verhas et al., Calif. Tissue Res. 39:74-77, 1986). While hirsute oligomenorrheic and amenorrheic women having low circulating E 2 levels would be expected to have reduced bone mass, these women with high androgen (but low estrogen) levels are at reduced risk of developing osteoporosis (Dixon et al., Clinical Endocrinology 30:271-277, 1989). Adrenal androgen levels have been found to be reduced in osteoporosis (Nordin et al., J. Clin. Endocr. Metab. 60:651, 1985). Moreover, elevated androgens in postmenopausal women have been shown to protect against accelerated bone loss (Deutsch et al., Int. J. Gynecol. Obstet. 25:217-222, 1987; Aloia et al., Arch. Int. Med. 143:1700-1704, 1983). In agreement with such a role of androgens, urinary levels of androgen metabolites are lower in postmenopausal symptomatic menopausis than in matched controls and a significant decrease in conjugated dehydroepiandrosterone (DHEA) was found in the plasma of osteoporotic patients (Hollo and Feher, Acta Med. Hung. 20:133, 1964; Urist and Vincent, J. Clin. Orthop. 18:199, 1961; Hollo et al., Acta Med. Hung. 27:155, 1970). It has even been suggested that postmenopausal osteoporosis results from both hypoestrogenism and hypoandrogenism (Hollo et al., Lancet:. 1357, 1976). As a mechanism for the above-suggested role of both estrogens and androgens in osteoporosis, the presence of estrogen (Komm et al., Science 241:81-84, 1988; Eriksen et al., Science 241:84-86, 1988) as well as androgen (Colvard et al., Proc. Natl. Acad. Sci. 86:854-857, 1989) receptors in osteoblasts could explain increased bone resorption observed after estrogen and androgen depletion. In boys, during normal puberty, an increase in serum testosterone levels procedes an increase in alkaline phosphate activity (marker of osteoblastic activity) which itself precedes increased bone density (Krabbe et al., Arch. Dis. Child. 54:950-953, 1979; Krabbe et al., Arch. Pediat. Scand. 73:750-755, 1984; Riis et al., Calif. Tissue Res. 37:213-217, 1985). While, in women, there is a rapid bone loss starting at menopause, bone loss in males can be recognized at about 65 years of age (Riggs et al., J. Clin. Invest. 67:328-335, 1987). A significant bone loss is seen in men at about 80 years of age, with the accompanying occurrence of hip, spine and wrist fractures. Several studies indicate that osteoporosis is a clinical manifestation of androgen deficiency in men (Baran et al., Calcif. Tissue Res. 26:103-106, 1978; Odell and Swerdloff, West. J. Med. 124:446-475, 1976; Smith and Walker, Calif. Tissue Res. 22 (Suppl.):22,5-228, 1976). Although less frequent than in women osteoporosis can cause significant morbidity in men (Seeman et al., Am. J. Med. 75:977-983, 1983). In fact, androgen deficiency is a major risk for spinal compression in men (Seeman et al., Am. J. Med. 75:977-983, 1983). Decreased radial and spinal bone density accompanies hypogonadism associated with hyperprolactinemia (Greespan et al., Ann. Int. Med. 104:777-782, 1986) or anaorexia nervosa (Rigotti et al., JAMA 256:385-288, 1986). However, in these cases, the role of hyperprolactinemia and loss in body weight is uncertain. Hypogonadism in the male is a well-recognized cause of osteoporotic fracture (Albright and Reinfenstein, 1948; Saville, Clin. End. Metab. 2:177-185, 1973). Bone density is in fact reduced in both primary and secondary hypogonadism (Velentzas and Karras. Nouv. Presse Medicale 10:2520, 1981). Severe osteopenia as revealed by decreased cortical and trabecular bone density was reported in 23 hypogonadotropic hypogonadal men (Finkelstein et al., Ann. Int. Med. 106:354-361, 1987; Foresta et al., Horm. Metab. Res. 15:56-57, 1983). Osteopenia has also been reported in men with Klinefelter's syndrome (Foresta et al., Horm. Metab. Res. 15:206-207, 1983; Foresta et al., Horm. Metab. Res. 15:56-57, 1983; Smith and Walker, Calif. Tissue Res. 22:225-228, 1977). Androgenic-reversible decreased sensitivity to calcitonin has been described in rats after castration (Ogata et al., Endocrinology 87:421, 1970; Hollo et al., Lancet 1:1205, 1971; Hollo et al., Lancet 1:1357, 1976). In addition, serum calcitonin has been found to be reduced in hypogonadal men (Foresta et al., Horm. Metab. Res. 15:206-207, 1983) and testosterone therapy in castrated rats increases the hypocalcemic effect of caldtonin (McDermatt and Kidd, End. Rev. 8:377-390, 1987). Albright and Ruferstein (1948) originally suggested that androgens increase the synthesis of bone matrix. Androgens have also been shown to increase osteoid synthesis and mineralization in chicken (Puche and Rosmano, Calif. Tissue Res. 4:39-47, 1969). Androgen therapy in hypogonadal men increases skeletal growth and maturation (Webster and Hogkins, Proc. Soc. Exp. Biol. Med. 45:72-75, 1940). In addition, testosterone therapy in man has been shown to cause positive nitrogen, calcium and phosphate balance (Albright, F., Reifeinstein, E. C. In: The parathyroid glands and metabolic bone disease. Williams and Williams Co.: Baltimore, pp. 145-204, 1948). As studied by bone histomorphometry, testosterone therapy in hypogonadal males resulted in increases in relative osteoid volume, total osteoid surface, linear extend of bone formation and bone mineralization (Barau et al., Calcif. Tissue Res. 26:103-106, 1978). Treatment with testosterone has been shown to increase osteoid surfaces and beam width with unchanged or reduced oppositional rates, thus indicating and increase in total bone mineralization rate (Peacock et al., Bone 7:261-268, 1986). There was also a decrease in plasma phosphate probably due to an effect on renal tubular reabsorption of phosphates (Selby et al., Clin. Sci. 69:265-271, 1985). Cortical bone density increases in hyperprolactinemic men with hypogonadism when testicular function is normalized (Greenspan et al., Ann. Int. Med. 104:777-782, 1986; Greenspan et al., Ann. Int. Med. 110:526-531, 1989). Testosterone therapy increases bone formation in men with primary hypogonadism (Baron et al., Calcif. Tissue Res. 26:103-106, 1978; Francis et al., Bone 7:261-268, 1986). In 21 hypogonadal men with isolated GnRH deficiency, normalization of serum testosterone for more than 12 months increased bone density (Kinkelstein et al., J. Clin. Endocr. Metab. 69:776-783, 1989). In men with already fused epiphyses, however, there was a significant increase in cortical bone density while no significant change was observed on trabecular bone density, thus supporting previous suggestions of variable sensitivity of cortical and trabecular bone to steroid therapy. Previous studies with anabolic steroids in small numbers of patients have suggested positive effects on bone (Lafferty et al., Ann. J. Med. 36:514-528, 1964; Riggs et al., J. Clin. Invest. 51:2659-2663, 1972; Harrison et al., Metabolism 20:1107-1118, 1971). More recently, using total body caldum measurements by neutron activation as parameter, the anabolic steroid methandrostenolone has shown positive and relatively long-term (24-26 months) effects in a double-blind study in postmenopausal osteoporosis (Chessnut et al., Metabolism 26:267-277, 1977; Aloia et al., Metabolism 30:1076-1079, 1981). The anabolic steroid nandrolone decanoate reduced bone resorption in osteoporotic women (Dequeker and Geusens, Acta Endocrinol. 271 (Suppl.):45-52, 1985) in agreement with the results observed during estrogen therapy (Dequeker and Ferin, 1976, see Dequeker and Geusens). Such data confirm experimental data in rabbits and dogs when nandrolone decanoate reduced bone resorption (Ohem et al., Curr. Med. Res. Opin. 6:606-613, 1980). Moreover, in osteoporotic women (Dequeker and Geusens, Acta Endocrinol. (Suppl.) 271:45-52, 1985) the anabolic steroid not only reduced bone loss but also increased bone mass. Vitamin D treatment, on the other hand, only reduced bone resorption. Therapy of postmenopausal women with nandrolone increased cortical bone mineral content (Clin. Orthop. 225:273-277). Androgenic side effects, however, were recorded in 50% of patients. Such data are of interest since while most therapies are limited to an arrest of bone loss, an increased in bone mass was found with the use of the anabolic steroid nandrolone. A similar stimulation of bone formation by androgens has been suggested in a hypogonadal male (Baran et al., Calcif. Tissue Res. 26:103, 1978). The problem with regimens which inhibit bone resorption with calcium, calcitriol or hormones is that they almost certainly lead to suppression of bone formation (Need et al., Mineral. Electrolyte Metabolism 11:35, 1985). Although, Albright and Reiferestein (1948) (See Need, Clin. Orthop. 225:273, 1987) suggested that osteoporosis is related to decreased bone formation and will respond to testosterone therapy, the virilizing effects of androgens have made them unsuitable for the treatment of postmenopausal women. Anabolic steroids, compounds having fewer virilizing effects, were subsequently developed. Although, minimal effects have been reported by some (Wilson and Griffin, Metabolism 28:1278, 1980) more positive results have been reported (Chessnut et al., Metabolism 32:571-580, 1983; Chessnut et al., Metabolism 26:267, 1988; Dequeker and Geusens, Acta Endocrinol. (Suppl. 110) 271:452, 1985). A randomized study in postmenopausal women has been shown an increase in total bone mass during treatment with the anabolic steroid stanazolol although side effects were recorded in the majority of patients (Chessnut et al., Metabolism 32:571-580, 1983). As mentioned above, the doses of "progestins" (for example medroxyprogesterone acetate) used for the standard therapy of breast cancer are accompanied by undesirable important side effects (especially those related to interaction of the steroid with the glucocorticoid receptor, especially Cushingoid syndrome, euphoria) (Mattsson, Breast Cancer Res. Treatm. 3:231-235, 1983; Blossey et al., Cancer 54:1208-1215, 1984; Hortobagyi et al., Breast Cancer Res. Treatm. 5:321-326, 1985; Von Veelen et al., Cancer Chemother. Pharmacol. 15:167-170, 1985). The term "progestin" refers to derivatives of progesterone and testosterone. Such progestins have, at times, been synthesized with the aim of developing compounds acting as analogs of progesterone on the progesterone receptors, especially for the control of fertility. With the availability of new and more precise tests, however, it became evident that such compounds, originally made to interact exclusively with the progesterone receptor, do also interact, frequently with high affinity, with the androgen receptor (Labrie et al., Fertil. Steril. 28:1104-1112, 1977; Labrie et al., Fertil. Steril. 31:29-34, 1979; Labrie, C. et al., J. Steroid Biochem. 28:379-384, 1987; Labrie C. et al., Mol. Cell. EndocrinoL 68:169-179, 1990). Sometimes, the androgenic activity of these compounds, especially at low concentrations, becomes more important than the true progestin activity. This is the case, for example, for medroxyprogesterone acetate (Poulin et al., Breast Cancer Res. Treatm. 13:161-172, 1989). A problem with prior-art treatments of breast and endometrial cancer with synthetic progestins is the side effects observed with such treatments. The blockade of estrogens, another common treatment for breast cancer, would have undesirable deleterious effects on bone mass in women. Similarly, blockade of estrogens, a common treatment for endometriosis, has similar undesirable deleterious effects on bone mass in women. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for prevention and treatment of breast cancer, endometrial cancer, osteoporosis and endometriosis, while substantially avoiding undesirable side effects. It is another object of the invention to provide a method for prevention of cancer having more specific effectiveness in delaying tumor growth. It is another object of the invention to provide a method for prevention of breast and endometrial cancer having significantly reduced frequency of unwanted side effects. It is another object of the invention to provide a method for prevention of bone loss in men and women having a reduced frequency of unwanted side effects. It is another object of the invention to provide a method for prevention of bone loss in women where estrogen formation and/or action is blocked in order to treat various estrogen-sensitive diseases, including cancer. It is another object of the invention to provide a method for prevention of bone loss in women already exposed to low estrogens following menopause. It is a further object of the invention to provide kits and pharmaceutical compositions for use in the methods described herein. These and other objects are achieved by practicing the methods disclosed herein and/or by utilizing the pharmaceutical compositions and kits disclosed herein. In one embodiment, a method is provided for activating androgen receptors in a warm blooded animal, including a human, comprising administering to said animal at least one androgenic steroid having a Ki value of less than 2×10 -8 M for the androgen receptor, an androgen receptor-mediated inhibitory effect on the growth of human breast cancer ZR-75-1 cells which reaches half-maximal value at a concentration below 3.0 nanomoles per liter, and no visible masculinizing activity at blood serum concentrations below 50 nM, wherein every such androgenic steroid is administered at a dosage sufficiently low to maintain a cumulative serum concentration below 50 nanomoles per liter. The methods of said androgenic steroid described herein are particularly useful for the treatment of human breast or endometrial cancer, osteoporosis or endometriosis. It is believed that the methods are also suitable for all purposes which are enhanced by administering androgens or otherwise activating androgen receptors. Both treatment and prevention of the diseases and disorders discussed herein are contemplated within the scope of the invention. It is believed that the methods of the invention are suitable for both prophylactic and therapeutic use. The compounds utilized have the special property of possessing potent androgenic activity at low blood concentration (e.g. less than 50 nM) while exhibiting very little glucocorticoid receptor activity at those concentrations. They are also characterized by the absence of physical masculinizing activity in females at the concentration range at which they are used. This is to be distinguished from natural androgens produced in gonadal or peripheral tissues such as testosterone and dihydrotestosterone which exhibit considerable masculinizing activity even at low blood concentrations. Synthetic progestins, e.g. progesterone derivatives are useful for this invention, as are some anabolic steroids. The androgens of the invention on average do not cause physically detectable increase in masculinizing effects such as increased hair growth in females, acne, seborrhea or hair loss. These masculinizing effects have been quantified in the literature. See, for example, Ferriman and Gallwey, J. P. Clin. Endocrinol. Metab. 21:1440-1447, 1961 (regarding hair growth); Cremoncini et al., Acta. Eur. Fertil. 7:248-314, 1976 (acne, seborrhea and hair loss). See also Cusan et al., J. Am. Acad. Dermatol. 23:462-469, 1990. Tables 1 and 2 below set forth a quantification. TABLE 1______________________________________Definition of hair grading at each of 11 sites(Grade 0 at all sites indicates absence of terminal hair)Site Grade Definition______________________________________ 1. Upper lip 1 A few hairs at outer margin 2 A small moustache at outer margin 3 A moustache extending halfway from outer margin 4 A moustache extending to mid-line 2. Chin 1 A few scattered hairs 2 Scattered hairs with small concentrations 3 & 4 Complete cover, light and heavy 3. Chest 1 Circumareolar hairs 2 With mid-line hair in addition 3 Fusion of these areas, with three- quarter cover 4 Complete cover 4. Upper back 1 A few scattered hairs 2 Rather more, still scattered 3 & 4 Complete cover, light and heavy 5. Lower back 1 A sacral tuft of hair 2 With some lateral extension 3 Three-quarter cover 4 Complete cover 6. Upper abdomen 1 A few mid-line hairs 2 Rather more, still mid-line 3 & 4 Half and full cover 7. Lower 1 A few mid-line hairs abdomen 2 A mid-line streak of hair 3 A mid-line band of hair 4. An inverted V-shaped growth 8. Arm 1 Sparse growth affecting not more than a quarter of the limb surface 2 More than this; cover still incomplete 3 & 4 Complete cover, light and heavy 9. Forearm 1,2,3,4 Complete cover of dorsal surface; 2 grades of light and 2 of heavy growth10. Thigh 1,2,3,4 As for arm11. Leg 1,2,3,4 As for arm______________________________________ TABLE 2______________________________________Grading of Acne, Seborrhea and Hair Loss______________________________________ Acne1. Isolated pustules, up to 10 in number2. More than 10 isolated pustules3. Clusters of pustules4. Confluent pustules Seborrhea1. Mild2. Moderate3. Severe Hair Loss1. Mild2. Obvious thinning3. Very obvious thinning4. Baldness______________________________________ Preferred compounds for use in the invention include synthetic progestins, anabolic steroids and other steroidal compounds having a Ki value of less than 2×10 -8 M for the androgen receptor, an androgen receptor-mediated inhibitory effect on the growth of human breast cancer ZR-75-1 cells reaching half-maximal value at a concentration below 3.0 nanomoles per liter, and lacking the masculinizing activity discussed above. Preferred androgens of the invention would cause no significant increase in the average masculinizing effect (e.g. a significant increase in any of the numerical grades set forth in Tables 1 or 2 above) observed in females following treatment for three months with blood concentrations of the androgen maintained at the top of the claimed concentration range (e.g. 50 nanomoles per liter). For most female patients for whom no masculinizing effects were visible prior to treatment, or a total score of 10 or less for all 11 sites indicated in Table 1 prior to treatment, the same score would normally be maintained during treatment in accordance with the present invention. That is, there would be no visible masculinizing effects after three months of treatment. For female patients displaying some masculinizing effects prior to treatment, it would be expected that those effects would not be increased by treatment. To determine whether the Ki values are below 2×10 -8 M, Ki values may be determined by the following method for measuring the affinity of various compounds for the androgen receptor. Preparation of prostatic tissue Ventral prostates are from Sprague-Dawley rats (Crl:CD(SD)Br) (obtained from Charles River, St-Constant, Qu ebec) weighing 200-250 g and castrated 24 h before sacrifice. Immediately after removal, prostates are kept on ice and used for the androgen binding assays. Preparation of cytosol Prostatic tissues are finely minced with scissors (fresh tissue) or pulverized with a Thermovac system (frozen tissue) before homogenization in buffer A (Tris, 0.025M; monothioglycerol, 20 mM; glycerol, 10% (v/v); EDTA, 1.5 mM and sodium molybdate, 10 mM, pH 7.4) in a 1:5 ratio (w/v) using a Polytron PT-10 homogenizer. These and all the following procedures are performed at 0°-4° C. The homogenate is centrifuged at 105000×g for 1 h in order to obtain the cytosolic fraction in the supernatant. Cytosolic androgen receptor assay Aliquots of 100 μl are incubated at 0°-4° C. for 18 h with 100 μl of 3 nM [ 3 H]T or [ 3 H] R1881 in the presence or absence of increasing concentrations of the non-labeled androgenic compound to be tested. At the end of the incubation, free and bound T or R1881 are separated by the addition of 200 μl dextran-coated charcoal (1% charcoal, 0.1% dextran T-70, 0.1% gelatin, 1.5 mM EDTA and 50 mM Tris (pH 7.4)) for 15 min before centrifugation at 2300×g for another 15 min at 0°-4° C. Aliquots (350 μl) of the supernatant are transferred to scintillation vials with 10 ml of an aqueous counting solution (Formula 963, New England Nuclear) before counting in a Beckman LS 330 counter (30% efficiency for tritium). Ki calculation Apparent inhibition constant "Ki" values are calculated according to the equation Ki=IC 50 /(1+S/K) (Cheng and Prusoff, Biochem. Pharmacol. 22:3099-3108, 1973). In this equation, S represents the concentration of [ 3 H]T or [ 3 H]R1881, K is the dissociation constant (K D ) of T or R1881 and IC 50 is the concentration of unlabeled compounds giving a 50% inhibition of T or R1881 binding. For numerous compounds, Ki values are reported in the literature. See, for example, Ojasso et al., J. Ster. Biochem. 27:255-269, 1987; Asselin et al., Cancer Res. 40:1612-1622, 1980; Toth and Zakar J. Steroid Biochem. 17:653-660, 1982. A method giving similar results is described in Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988. In order to determine the concentration at which a given compound reaches half-maximal androgen receptor-mediated inhibitory effect on the growth of human breast cancer ZR-75-1 cells, the following technique is utilized as described in detail in Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988. Maintenance of stock cultures The ZR-75-1 human breast cancer cell line can be obtained from the American Type Culture Collection (Rockville, Md.). The cells are routinely cultured in phenol red-free RPMI 1640 medium supplemented with 10 nM E 2 , 15 mM Hepes, 2 mM L-glutamine, 1 mM sodium pyruvate, 100 IU penicillin per ml, 100 μg streptomycin sulfate per ml, and 10% (v/v) fetal bovine serum (FBS), in a water-saturated atmosphere of 95% air:5% CO 2 at 37° C. Stock cultures in their logarithmic growth phase are harvested with 0.05% trypsin/0.02% EDTA (w/v) in Hanks' balanced salts solution and resuspended in E 2 - and phenol red-free RPMI 1640 medium containing 5% (v/v) dextran-coated charcoal (DCC)-treated FBS and 500 ng of bovine insulin per ml, but otherwise supplemented as described above for maintenance of stock cultures. Cells were plated in 24-well Linbro culture plates (Flow Laboratories) at a final density of 0.5-4.0×10 4 cells/well. Fourty-eight hours after plating, fresh SD medium containing the appropriate concentrations of steroids are added. The final concentration of ethanol used for the addition of test substances does not exceed 0.12% (v/v) and has no significant effect on cell growth and morphology. The incubation media are replaced every other day and cells are harvested by trypsinization after 12 days of treatment, unless otherwise indicated. Cell number can be determined with a Coulter Counter. Calculations and statistical analyses Apparent IC 50 values are calculated using an iterative least squares regression (Rodbard, Endocrinology 94:1427-1437, 1974), while apparent inhibition constants (Ki values) are calculated according to Cheng and Prusoff (Biochem. Pharmacol. 22:3099-3108, 1973). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a comparative graph over time of the number of tumors observed in a group of rats protected by a method in accordance with the invention following administration of dimethylbenz(a)anthracene (DMBA) versus an unprotected control group. FIG. 2 is a comparative graph of estradiol-stimulated growth of tumors in ovariectomized rats treated in accordance with the invention versus an untreated control group. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A better understanding of the multiple endocrine activity of synthetic progestins is required not only for their more rational use in the prevention and therapy of breast and endometrial cancers as well as endometriois and bone loss but also to avoid side effects caused by interaction with steroid receptors unnecessary for the desired beneficial effect. Precise analysis of the biological actions of synthetic "progestins" having affinity for many steroidal receptors would ideally require the selection of in vitro models possessing functional receptors for all major classes of steroids. For this purpose, we have chosen the ZR-75-1 human breast cancer cell line, which possesses functional receptors for estrogens, androgens, progesterone and glucocorticoids (Vignon et al., J. Clin. Endocrinol. Metab. 56:1124-1130, 1983) in order to compare the relative contribution of the different steroid receptor systems in the control of cell proliferation by synthetic progestins. While estrogens are strongly mitogenic in ZR-75-1 cells (Poulin and Labrie, Cancer Res. 46:4933-4937, 1986) and specifically regulate the expression and/or the secretion of several proteins (Dickson and Lippman, Endocr. Rev. 8:29-43, 1987), androgens (Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988), glucocorticoids (Hatton, A. C., Labrie, F., unpublished results) as well as progestins (Poulin et al., Breast Cancer Res. Treatm. 13:161-172, 1989) inhibit their proliferation through specific interactions with their respective receptors. Many progestins have been used in the treatment of breast cancer, including MPA (Blossey et al., Cancer 54:1208-1215, 1984; Hortobayyi et al., Breast Cancer Res. Treatm. 5:321-326, 1985), MGA (Johnson et al., Semin. Oncol. 13 (Suppl.):15-19, 1986; Tchekmedyan et al., Semin. Oncol. 13 (Suppl.):20-25, 1986) and norethindrone (Clavel et al., Eur. J. Cancer Clin. Oncol. 18:821-826, 1982; Earl et al., Clin. Oncol. 10:103-109, 1984). Using the in vitro system of human breast cancer ZR-75-1 cells, I have found that the synthetic progestins or anabolic steroids, Nor-testosterone, R1881, dromostanolone, fluoxymesterone, ethisterone, methandrostanolone, oxandrolone, danazol, stanozolol, calusterone, oxymetholone, cyproterone acetate, chlormadinone acetate and norgestrel, possess androgenic activity at low concentrations. In addition to inhibition of cell growth, the secretion of two glycoproteins, namely gross cystic disease fluid protein-15 (GCDFP-15) and GCDFP-24 is markedly stimulated by androgens (Simard et al., Mol. Endocrinol. 3:694-702, 1989; Simard et al., Endocrinology 126:3223-3231, 1990). Measurements of GCDFP-25 or GCDFP-24 secretion can thus be used as sensitive parameter or marker of androgen action in these cells. In fact, changes in GCDFP-15 and GCDFP-24 secretion are opposite to the changes in cell growth under all experimental conditions examined. All the synthetic progestins or anabolic steroids that I have studied exhibit androgenic activity on ZR-75-1 breast cancer growth and secretion of GCDFP-15 and GCDFP-24. Identification of the receptors (estrogen, androgen, progesterone and glucocorticoid) responsible for the action of the compounds is essential in order to assess the potential actions (including adverse effects) of such compounds. It is thus especially important to assess the specific interaction at low concentrations with the androgen receptor since such low concentrations do not interact with the glucocorticoid receptor, thus avoiding or minimizing secondary side effects. One method for inhibiting growth of breast and endometrial cells is activation of the androgen receptor with an effective compound having an affinity for the receptor site such that is binds to the androgen receptor at low concentrations while not significantly activating other classes of steroid receptors linked to potential side effects. It is important to select compounds having maximal affinity for the androgen receptor which have minimal or no virilizing effects in women. In order to minimize interaction of such compounds with the glucocorticoid and estrogen receptors, it is important to use low dose of the compounds. It is also important to choose steroids having androgenic activity at low concentrations which are not metabolized into estrogens under in vivo conditions which, at the low concentrations used, will not lead to significant activation of receptors other than the androgen receptors. My research has shown that the compounds used in the invention, particularly anabolic steroids and synthetic progestins, vary markedly, over different concentrations, in their ability to activate different classes of steroidal receptors. Hence, by carefully controlling concentration, it is possible to selectively cause activation of desired receptors while not causing significant activation of undesired receptors. For example, at the low concentrations specified herein, MPA can be utilized to desirably activate androgen receptors while substantially avoiding side effects associated with glucocorticoid activation which have plagued prior art treatments. Thus, this invention provides a novel method for prevention and therapy of breast and endometrial cancer as well as other diseases responsive to activation of the androgen receptor, e.g. bone loss and endometriosis. In this invention, the amount of the androgenic compounds administered is much lower than previously used in art for the treatment of breast and endometrial cancer. MONITORING BLOOD CONCENTRATION OF ANDROGENS OF THE INVENTION To help in determining the potential effects of the treatment, blood concentrations of the compound can be measured. For example, measurements of plasma medroxyprogesterone acetate (MPA) levels can be made by radioimmunoassay following extraction as follows: Antibody preparation Antibody 144A was raised in rabbits against 17-hydroxyprogesterone-3-0-carboxymethyloxime-BSA. The labeled steroid used in the radioimmunoassay (RIA) was methyl-17α-hydroxyprogesterone acetate, 6α-[1,2- 3 H(N)]- obtained from NEN (CAT NO:NET 480) while the reference preparation was medroxyprogesterone acetate (MPA) obtained from Steraloids. The assay buffer used was 0.1% gelatin in 0.1M sodium phosphate, 0.15M sodium chloride, 0.1% sodium azide, pH 7.2. The extraction solvent mixture was ethyl ether-acetone (9:1, v:v) [EEA] while the LH-20 chromatography solvent mixture was iso-octane:toluene:methanol (90:5:5;v:v:v) [IOTH]. Extraction procedure One ml of plasma was extracted twice with 5 ml of EEA. The extracts were evaporated to dryness with nitrogen and the remaining residue was dissolved in one ml of IOTH. The extracts were then subjected to LH-20 chromatography on 10×30 cm columns (Corning CAT NO:05 722A) filled with 2 g of LH-20 (Pharmacia). The gel was washed with 30 ml of IOTH before addition of one ml of sample and elution with IOTH. The first 6 ml were discarded. The following 10, 16.5 and 27.5 ml of eluent were fraction I (progesterone), II (MPA) and Ill (17-LH-progesterone), respectively. Fraction II was evaporated to dryness and reconstituted in 1.5 ml of assay buffer. Radioimmunoassay To each 12×75 mm borosilicate test tube was added:0.2 ml containing 25,000 DPM of tritiated steroid, 0.5 ml of reference preparation ranging from 5 to 5000 pg/tube or 0.5 ml of extracted sample fraction II, 0.2 ml of antiserum 144A diluted 1/5000 or 0.2 ml of assay buffer to account for non specific binding. The tubes were then incubated overnight at 4° C. Then, 0.2 ml 2% charcoal Norit-A, 0.2% Dextran T-70 diluted in water was added. The tubes were then shaken gently and, after 10 min, they were centrifuged at 2000×g for 10 min. The supernatant was mixed with 8 ml of Formula-989 (NEN:NEF-989) and the radioactivity was counted in a β-counter. The lower and upper limits of detection of MPA are 10 and 10000 pg/ml, respectively, while the slope (LOGIT-LOG) is -2.2 and the ED 50 value is 315 pg/ml. Non-specific and net binding are 1.5 and 45%, respectively. Antibody 144A is highly specific for MPA since cross-reactivity with progesterone, 20α-OH-Prog, pregnenolone, 17-OH-pregnenolone, DHT, androstenedione, testosterone, 3α-diol, estrone, estradiol and cortisol is less than 0.1%. Calculations and statistics RIA data were analyzed using a program based on model II of Roadbard and Lewald (In:2nd Karolinska Symposium, Geneva, 1970, pp. 79-103). Plasma MPA levels are usually shown as the means ±SEM (standard error of the mean) of duplicate measurements of individual samples. Statistical significance is measured according to the multiple-range test of Duncan-Kramer (Kramer, C. Y., Biometrics 12:307-310, 1956). A test compounds relative effect on various receptors To assist in determining the activity of the potential compounds on the various steroid receptors, androgen, glucocorticoid, progesterone and estrogen-receptor-mediated activities of synthetic progestins and anabolic steroids can be measured in ZR-75-1 human breast cancer cells using cell growth as well as GCDFP-15 and GCDFP-24 release as parameters of response (Poulin and Labrie, Cancer Res. 46:4933-4937, 1986; Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988; Poulin et al., Breast Cancer Res. Treatm. 13:161-172, 1989; Poulin et al., Breast Cancer Res. Treatm. 13:265-276, 1989; Simard et al., Mol. Endocrinol. 3:694-702, 1989; Simard et al., Endocrinology 126:3223-3231, 1990). The following properties permit measurement of progesterone receptor (PgR) activity:1) the addition of insulin completely reverses the inhibition due to the interaction of the progestin R5020 with the PgR in ZR-75-1 cells; and 2) the antiproliferative effect of R5020 is observed only under E 1 -stimulated conditions. These two characteristics of ZR-75-1 cell growth permit study of the extent to which a tested compound's effects on ZR-75-1 cells are attributated to its interaction with PgR by evaluating the effect of insulin and/or estrogen addition on the growth response measured at the end of a 15-day incubation of ZR-75-1 cells with the test compounds. The contribution of the estrogen receptor (ER), on the other hand, can be directly measured by incubating ZR-75-1 cells in the presence or absence of estrogen in the medium. In order to analyze the interactions of synthetic progestins or anabolic steroids with the androgen receptor (AR) and glucocorticoid receptor (GR) in their inhibitory action on cell growth, one takes advantage of the additivity of the anti-proliferative effects of androgens and glucocorticoids in this cell line (Poulin et al., Breast Cancer Res. Treatm. 12:213-225, 1988; Hatton and Labrie, F., unpublished data). Thus, one can saturate AR with 5α-dihydrotestosterone (DHT) and then measure the effect on cell proliferation resulting from the addition of a putative glucocorticoid. On the other hand, the effect of a putative androgen can similarly be measured following saturation of GR by dexamethasone (DEX). The specificity of the growth-inhibitory activity thus observed with the test compound can also be further assessed by its reversibility using the appropriate antagonist (i.e. antiglucocorticoid or antiandrogen). Thus, in the presence of excess androgen (1 μM DHT) in the presence of E 2 and insulin, glucocorticoid effects can be assessed with precision and with no interference by the other receptors. The same applies to study of the role of AR when the cells are incubated in the presence of excess glucocorticoid (3 μM DEX), in the presence of E 2 and insulin. As demonstrated by detailed kinetic studies, 1 μM DHT and 3 μM DEX exert maximal inhibitory effects on the AR and GR, respectively. In addition, the possible antagonistic activities of "progestins" mediated through the AR and GR can be determined by saturating both receptor systems with DHT and DEX with one ligand being in far greater excess than the other in order to allow reversal through a single chosen receptor at a time. All experiments are performed with ZR-75-1 cells grown in E 2 -supplemented media containing insulin in order to prevent the PgR-mediated effect of "progestins" on cell growth. Using the foregoing techniques, I have found that numerous androgenic compounds which also activate other receptors (e.g. glucocorticoid or progesterone receptors) vary in their relative effects on different receptors as a function of concentration. By staying within concentration ranges defined herein, compounds of the invention may beneficially affect androgen receptors without substantial undesirable effects on other receptors. Selection of patients who may benefit from the method's described herein The appearance of breast cancer is usually detected by self breast examination and/or mammography. Endometrial cancer, on the other hand, is usually diagnosed by endometrial biopsy. Both cancers can be diagnosed and evaluated by standard physical methods well known to those skilled in the art, e.g. bone scan, chest X-Ray, skeletal survey, ultrasonography of the liver and liver scan (if needed), CAT scan, MRI and physical examination. Endometriosis can be diagnosed following pains or symptoms assodated with menstruations in women while definitive diagnosis can be obtained by laparascopy and, sometimes, biopsy. Bone density, on the other hand, can be measured by standard methods well known to those skilled in the art, e.g. QDR (Quantitative Digital Radiography), dual photon absorptiometry and computerized tomography. Plasma and urinary calcium and phosphate levels, plasma alkaline phosphatase, calcitonin and parathormone concentrations, as well as urinary hydroxyproline and caldum/creatinine ratios. Breast or endometrial cancer, osteoporosis or otherwise insufficient bone mass, and other diseases treatable by activating androgen receptor may be treated in accordance with the present invention or prophylactically prevented in accordance herewith. Typically suitable androgenic compounds include 6-alpha-methyl,17-alpha-acetoxy progesterone or medroxyprogesterone acetate available, for example, from Upjohn and Farmitalia Carlo Erba, S.p.A. under the trade names Provera, DepoProvera or Farlutal, and the acronym MPA. Other suitable androgenic compounds include those described in Labtie et al. (Fertil. Steril. 31:29-34, 1979) as well as anabolic steroids or progestins (Raynaud and Ojasso, In: Innovative Approaches in Drug Research, Elsevier Sci. Publishers, Amsterdam, pp. 47-72, 1986; Sandberg and Kirdoni, Pharmac. Ther. 36:263-307, 1988; and Vincens, Simard and De Ligni eres, Les Androg enes. In: Pharmacologie Clinique, Base de Thr eapeutique, 2i eme Edition, Expansion Scientifique (Paris), pp. 2139-2158, 1988), as well as Calusterone (7β,17α-dimethyltestosterone), anabolic steroids (Lain, Am. J. Sports Medicine 12, 31-38, 1984; Hilf, R., Anabolic-androgenic steroids and experimental tumors. In: (Kochachian, C. D., eds.), Handbook of Experimental Pharmacology, vol. 43, Anabolic-Androgenic Steroids, Springer-Verlag, Berlin, 725 pp, 1976), fluoxymesterone (9α-fluoro-11β-hydroxy-17α-methyltestosterone), testosterone 17β-cypionate, 17α-methyltestosterone, Pantestone (testosterone undecanoate), Δ 1 -testololactone and Andractim. Other typical suitable androgenic compounds are cyproterone acetate (Androcur) available from Shering AG, 6-alpha-methyl, 17-alpha-acetoxy progesterone or medroxyprogesterone acetate (MPA) available from, among others, Upjohn and Farmitalia, Calbo ERba, Gestodene available from Shering, megestrol acetate (17α-acetoxy-6-methyl-pregna-4,6-diene-3,20-dione) available from Mead Johnson & Co., Evanswille, Ind., under the trade name of Megace. Other synthetic progestins include Levonorgestrel, Norgestimate, desogestrel, 3-ketodesogestrel, norethindrone, norethisterone, 13α-ethyl-17-hydroxy-18,19-dinor-17β-pregna-4,9,11-triene-20-yn-3-one (R2323, gestrinone), demegestone, norgestrienone, gastrinone and others described in Raynaud and Ojasso, J. Steroid Biochem. 25:811-833, 1986; Raynaud et al., J. Steroid Biochem. 25:811-833, 1986; Raynaud et al., J. Steroid Biochem. 12:143-157, 1980; Raynaud, Ojasoo and Labrie, Steroid Hormones, Agonists and Antagonists, In: Mechanisms of Steroid Action (G. P. Lewis and M. Ginsburg, eds), McMillan Press, London pp. 145-158 (1981). Any other progestin derivative having the above-described characteristics could also be useful for the invention. The androgenic compound is preferably administered as a pharmaceutical composition via topical, parenteral or oral means. The compound can be administered parenterally, i.e. intramuscularly or subcutaneously by injection of infusion by nasal drops, by suppository, or where applicable intravaginally or transdermally using a gel, a patch or other suitable means. The androgenic compound may also be microencapsulated in or attached to a biocompatible, biodegradable polymer, e.g. poly(d1,1-lactide-co-glycolide) and subcutaneously or intramuscularly injected by a technique called subcutaneous or intramuscular depot to provide continuous, slow release of the compound over a period of 30 days or longer. In addition to the oral route, a preferred route of administration of the compound is subcutaneous depot injection. DepoProvera can be released at a relatively constant rate for approximately 3 months after intramuscular administration of an aqueous suppression. The amount of each compound administered is determined by the attending clinician taking into consideration the patient's condition and age, the potency of each component and other factors. In the prevention of breast and endometrial cancer, as well as bone loss, according to this invention, the following dosage ranges are suitable. The androgenic composition is preferably administered in a daily dosage which delivers less than 25 mg of active androgenic steroid per 50 kg of body weight. A dosage of 1-10 mg per 50 kg of body weight, especially 3-7 mg (e.g. 5 mg) is preferred. The dosage selected preferably maintains serum concentration below 50 nanomoles per liter, preferably between 1.0 nanomoles per liter and 10, 15 or 25 nanomoles per liter depending on patient's response. The dosage needed to maintain these levels may vary, from patient to patient. It is advisable for the attending clinicial to monitor levels by the techniques described herein and optimize dosage accordingly. For prophylactic purposes, administration of the androgen is preferably started in the perimenopausal period for the prevention of breast and endometrial cancer and bone loss in normal women. The androgen may be associated with an accepted dose of an estrogen used to prevent other signs and symptoms of menopause. In women, when estrogen formation and/or action has been blocked for treatment of endometriosis, leiomyomata, breast cancer, uterine cancer, ovarian cancer or other estrogen-sensitive disease, administration of the androgen can be started at any time, preferably at the same time as blockade of estrogens. The androgen for intramuscular or subcutaneous depot injection may be microencapsulated in a biocompatible, biodegradable polymer, e.g., poly(d,1-lactide-co-glycolide) by, among other techniques, a phase separation process or formed into a pellet or rod. The microspheres may then be suspended in a carrier to provide an injectable preparation or the depot may be injected in the form of a pellet or rod. See also European patent application EPA No. 58,481 published Aug. 25, 1982 for solid compositions for subdermal injection or implantation or liquid formulations for intramuscular or subcutaneous injections containing biocompatible, biodegradable polymers such as lactide-glycolide copolymer and active compounds. These formulations permit controlled release of the compound. The androgens useful in the present invention can be typically formulated with conventional pharmaceutical excipients, e.g., spray dried lactose and magnesium stearate into tablets or capsules for oral administration. The active substance can be worked into tablets or dragee cores by being mixed with solid, pulverulent carrier substances, such as sodium citrate, calcium carbonate or dicalcium phosphate, and binders such as polyvinyl pyrrolidone, gelatin or cellulose derivatives, possibly by adding also lubricants such as magnesium stearate, sodium lauryl sulfate, "Carbowax" or polyethylene glycol. Of course, taste-improving substances can be added in the case of oral administration forms. As further forms, one can use plug capsules, e.g., of hard gelatin, as well as closed soft-gelatin capsules comprising a softener or plasticizer, e.g. glycerine. The plus capsules contain the active substance preferably in the form of granulate, e.g., in mixture with fillers, such as lactose, saccharose, mannitol, starches, such as potato starch or amylopectin, cellulose derivatives or highly dispersed silicic acids. In soft-gelatin capsules, the active substance is preferably dissolved or suspended in suitable liquids, such as vegetable oils or liquid polyethylene glycols. In place of oral administration, the active compound may be administered parenterally. In such case, one can use a solution of the active substance, e.g., in sesame oil or olive oil. The active substance can be microencapsulated in or attached to a biocompatible, biodegradable polymer, e.g. poly(d,1-lactide-co-glycolide) and subcutaneously or intramuscularly injected by a technique called subcutaneous or intramuscular depot to provide continuous slow release of the compound(s) for a period of 2 weeks or longer. The invention also includes kits or single packages containing the pharmaceutical composition active ingredients or means for administering the same for use in the prevention and treatment of breast and endometrial cancer as well as bone loss and treatment of endometriosis as discussed above. The kits or packages may also contain instructions on how to use the pharmaceutical compositions in accordance with the present invention. Following the above therapy using the described regimen, tumor growth of breast and endometrial cancer as well as bone loss and endometriosis can be relieved while minimizing adverse side effects. The use of the described regimen can also prevent appearance of the same diseases. EXAMPLE 1 Prevention of Mammary Carcinoma Induced by Dimethylbenz(a)anthracene (DMBA) in the Rat, By Low Dose Medroxrogesterone Acetete ("MPA") To illustrate the efficacy of the present invention in reducing the incidence of mammary carcinoma, FIG. 1 illustrates the effect of a single subcutaneous injection of Depo-Provera (Medroxyprogesterone Acetate (MPA) (30 mg)) one week before inducing carcinoma with dimethylbenz(a)anthracene. FIG. 1 shows the period from 30 to 85 days following administration of DMBA. One curve in FIG. 1 shows the average number of tumors per animal in the group protected by Depo-Provera while the other curve shows the average number of tumors per animal in the unprotected group. It is estimated that the 30 mg. injection of Depo-Provera would release approximately 0.17 mg. of active medroxyprogesterone acetate per day over a six-month period. As may be seen by comparing the two graphs in FIG. 1, the Depo-Provera-treated group showed much greater resistance to the development of tumors than did the unprotected group. After 85 days an average of 1.89 tumors per rat was observed in the unprotected group, while only 0.30 tumor per rat was observed in the Depo-Provera protected group. Tumor number and size measured with calipers were determined weekly. EXAMPLE 2 Treatment of Mammary Carcinoma Induced By Dimethylbenz(a)anthracene In the Rat, By Low Dose Medroxyprogesterone Acetate FIG. 2 illustrates the inhibition of mammary carcinoma growth which may be achieved in accordance with the methods of the invention. Tumors were induced in ovariectomized rats using dimethylbenz(a)anthracene. Estradiol was used to stimulate growth in both a treatment and control group of rats. Each animal in the treatment group received a single subcutaneous administration of 30 mg of Depo-Provera (which is estimated to release approximately 0.17 mg. per day of active medroxyprogesterone acetate for a period of about six months). This figure illustrates the average estradiol-stimulated change in total tumor area in each group following treatment. As may be seen in FIG. 2, the group treated with Depo-Provera exhibited significantly less tumor growth than the untreated group. The terms and descriptions used herein are preferred embodiments set forth by way of illustration only, and are not intended as limitations on the many variations which those of skill in the art will recognize to be possible in practicing the present invention as defined by patent claims based thereon.

A method of treatment or prevention of breast and endometrial cancer, osteoporosis and endometriosis in susceptible warm-blooded animals comprising administering a low dose of a progestin or other steroid derivative having androgenic activity and low masculinizing activity. Pharmaceutical compositions useful for such treatment and pharmaceutical kits containing such compositions are disclosed. An in vitro assay permitting specific measurements of androgenic activity of potentially useful compounds is also disclosed.

This application claims priority to U.S. Provisional patent application Ser. No. 60/052,443, of Roos et al.; filed Jul. 14, 1997, for COMMON AIR INTERFACE, incorporated herein by reference. This patent document relates to a common air interface described in a series of patent documents filed concurrently herewith. Related patent documents are: U.S. patent application Ser. No. 09/115,098, filed Jul. 13, 1998, of Joshi et al.; for SYSTEM AND METHOD FOR IMPLEMENTING TERMINAL TO TERMINAL CONNECTIONS VIA A GEOSYNCHRONOUS EARTH ORBIT SATELLITE, now U.S. Pat. No. 6,278,876; U.S. patent application Ser. No. 09/115,097, filed Jul. 13, 1998, of Roos, et al.; for MOBILE SATELLITE SYSTEM HAVING AN IMPROVED SIGNALING CHANNEL, U.S. patent application Ser. No. 09/115,096; filed Jul. 13, 1998, of Noerpel, et al.; for SPOT BEAM SELECTION IN A MOBILE SATELLITE COMMUNICATION SYSTEM, now U.S. Pat. No. 6,233,451; U.S. patent application Ser. No. 09/115,101, filed Jul. 13, 1998, of Noerpel, et al.; for PAGING RECEPTION ASSURANCE IN A MULTIPLY REGISTERED WIRELESS TRANSCEIVER, now U.S. Pat. No. 6,282,178; U.S. patent application Ser. No. 09/115,095, filed Jul. 13, 1998, of Joshi, et al.; for IMMEDIATE CHANNEL ASSIGNMENT IN A WIRELESS SYSTEM, U.S. patent application Ser. No. 09/115,099, filed Jul. 13, 1998, of Joshi, et al.; for ERROR AND FLOW CONTROL IN A SATELLITE COMMUNICATIONS SYSTEM, now U.S. Pat. No. 6,289,482; U.S. patent application Ser. No. 09/115,100, filed Jul. 13, 1998, of Roos, et al.; for SYNCHRONIZATION OF A MOBILE SATELLITE SYSTEM WITH SATELLITE SWITCHING, all of which are incorporated herein by reference. BACKGROUND OF THE INVENTION The present invention relates to cellular and satellite communications. More particularly, the invention relates to a method and a system for providing signaling bursts for maintaining communications channel transmissions during periods of voice inactivity during ongoing voice communications between a transmitter and a receiver in a time division multiple access (TDMA) mobile satellite communication system. A mobile satellite communication system such as the Geosynchronous Earth Orbit Mobile (GEM) network discussed herein, typically includes one or more satellites, at least one fixed ground terminal such as a gateway system (GS) and several mobile access terminals (ATs). The access terminals typically communicate with the public switched telephone network (PSTN) or other mobile terminals via an air communication interface between the satellite and the gateway. Using the mobile access terminals, the satellite system provides a variety of telephony services. Satellite telephony systems as described herein share call processing information with terrestrial systems such as the GSM cellular system to allow compatibility between the satellite, cellular, and the public switch telephone network services. The terrestrial standards such as GSM may not apply directly to the mobile satellite communication system, more particularly the satellite air interface poses physical constraints not accounted for in the GSM architecture. A number of communication systems utilizing satellites and small mobile terminals provide voice and other information communication. In all such systems, the bandwidth and satellite power associated with the communication links may be expensive and wasteful of limited resources. In addition, the mobile access terminals such as hand-held terminals (HHTs), which are often small, hand-held devices, are constrained by power consumption and related battery life concerns. In maintaining an active voice communications channel, however, information must be transmitted on a regular basis for synchronization between the satellite and the access terminal, e.g., for timing, frequency, and power parameters. During voice communications, periods of voice inactivity may occur approximately half of the time. Therefore, appropriate design of burst formats, combined with voice activity detection, may provide significant power reduction. A number of specific concerns are associated with the form of information communications necessary for maintaining a communications channel, including power control information transfer requirements, power level consistency in the presence of highly variable power amplifiers, background noise level and characteristic communication, support for frequency and timing parameter tracking, timeliness of information delivery, and robust communications. Thus, there exists a need for a method and a system for performing Keep-Alive Burst (KAB) communications during periods of voice inactivity to maintain the integrity of the voice communication transmissions over a communications channel, and provide acceptable performance with a minimum amount of power being used by the satellite and access terminal systems. SUMMARY OF THE INVENTION In the following description, a satellite communications system is described. As will be appreciated by a skilled artist, however, the teachings of the present invention apply to many communications systems, not just satellite-based systems. Thus, references herein to satellite systems should be understood as being directed to specific embodiments, as opposed to the invention generally. Accordingly, the present invention, in particular embodiments, addresses a key opportunity for power savings at both the satellite and the access terminals to limit transmission of significant power to those times when voice communications is active. During periods of silence, which typically occur about sixty percent of the time, much less power may be transmitted. Nonetheless, for a variety of reasons discussed herein, some power continues to be required for transmissions during periods of voice inactivity in the form of bursts that are transmitted during such periods to maintain the integrity of the communications channel. Information transmitted during voice inactivity by such keep-alive bursts (KABs) may be categorized into two types of information, namely, explicit digital information and information implicit in the waveforms transmitted. By adopting a burst format which accounts for the necessary explicit and implicit information required for transmission during keep-alive bursts, a combination of various features in terms of power modulation in burst format results in reduced power and delay, and improves performance when compared with conventional techniques. Briefly summarized, the present invention relates a system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for storing of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver. It will be understood that both the foregoing and general description in the following detailed description are exemplary and intended to provide further explanation of the invention as claimed. The accompanying drawings provide an understanding of the invention as described in the preferred embodiments to illustrate the invention and serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a mobile satellite communication system in accordance with the present invention; FIG. 2 is a block diagram of a preferred embodiment of a mobile access terminal for use in the mobile satellite communication system of FIG. 1; FIG. 3 shows a keep-alive burst (KAB) structure timing diagram; FIG. 4 illustrates KAB transmission allocation positions in active communications traffic; FIG. 5 shows symbol position usage at the beginning of the KAB bursts; FIG. 6 shows the power distribution for the keep-alive bursts at the beginning of each burst; FIG. 7 is a table illustrating symbol utilization in the middle of channel TCH 2 ; FIG. 8 is a power distribution graph showing the power use per symbol position in channel TCH 2 ; FIG. 9 is a flowchart illustrating the determination of keep-alive burst positions; FIG. 10 is a flowchart illustrating the operation of keep-alive burst transmissions; and FIG. 11 is a flowchart illustrating the receive operation associated with the keep-alive burst transmissions of FIG. 10 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings and particularly to FIG. 1, a preferred embodiment of a mobile satellite communication system 10 is illustrated. The mobile communication system 10 , herein a Geosynchronous Earth Orbit Mobile satellite system (GEM) includes several mobile access terminals 12 and one or more satellites 14 . One or more gateway stations 16 (GS) are coupled to public switch telephone networks 18 (PSTN). The access terminal 12 is typically a hand-held telephone or vehicle-mounted telephone, but, as described in the present embodiment, the access terminal 12 may provide operation both as a GEM access terminal and as an GSM cellular telephone. While being used with the satellite communication systems described herein, the access terminal 12 communicates over an L-band frequency with a particular spot beam 20 with the satellite 14 . Each spot beam 20 is associated with a predetermined geographic region. The terrestrial gateway 16 communicates with the satellite 14 over a Ku-band frequency. The satellite 14 includes transponders for translating between the L-band spot beam 20 signals used by the access terminals 12 and the Ku-band 22 signals used by the gateway 16 . The gateway 16 interfaces with the terrestrial telephony carrier, such as PSTN 18 , and may also interface with a conventional cellular network such as GSM. Accordingly, users may place telephone calls using the access terminal 12 to either land line or cellular telephone users. As illustrated in FIG. 1, a plurality of gateways 16 may be employed, each providing similar functions and being employed to access, for example, respective public switched telephone networks 18 . The satellite 14 provides L-band-to-L-band bent pipe single hop communications, as well as satellite switched communications to support communications between the users of the access terminals 12 . At satellite 14 , the L-band 20 uplink and downlink are transmitted via multiple L-band spot beams 20 . Subscribers to the system 10 have unique telephone numbers allowing them to receive telephone calls when they are registered to receive pages from either the GEM or the GSM cellular network. Registration is automatic when the access terminal 12 is turned on, such that a registration procedure locates the access terminal 12 within a particular spot beam coverage area. In addition to originating calls, the access terminals 12 can receive calls from any terrestrial facility by connecting the call through the gateway station 16 , at which the gateway 16 determines the location of the access terminal 12 and sends a paging message to the access terminal 12 to announce the incoming call. The system 10 uses a low rate encoded or ciphered voice transmission. In the described embodiments, the access terminals 12 are provided with dual mode operation allowing for voice communications either via satellite or via the local cellular system, e.g., GEM and GSM as discussed herein. The gateway 16 provides for user mobility as users travel with the access terminal 12 from spot beam to spot beam. Additionally, the communication channels carried via the satellite 14 provides space segment resources used for control functions, i.e., one or more channels in each L-band spot beam 20 are control channels, e.g., the gateway 16 may place a forward control signal in each L-band spot beam 20 to allow synchronization of the access terminals 12 and to carry network control information from the gateway 16 to the access terminals 12 . The forward control channels allow the access terminals 12 to acquire a satellite carrier and identify the L-band spot beam 20 and gateway station 16 which originates the signal. The gateway 16 uses the forward control channel to page access terminals 12 using unique addresses to announce mobile terminated calls. Each L-band spot beam 20 preferably contains a return direction signaling channel that access terminals 12 use to initiate and register calls with the gateway 16 . During a call, in-band low data rate control channels are preferably available between the access terminals 12 and the gateway 16 for call supervision, power control, and to initiate call termination. For example, during burst communication between the access terminal 12 and the satellite 14 , a threshold signal may be established relating to the strength of the transmitted burst for setting a power control bit based on a comparison of received signal strength with threshold values. In addition to such information being transmitted during active voice communications, certain information must also be transmitted during voice inactivity by keep-alive bursts (KABs) which can be categorized as one of two types, namely, explicit digital information, and implicit information in the waveforms transmitted. Explicit digital information provided by the keep-alive bursts include a description of the background sounds present at the transmitter's microphone, and commands and status messages associated with power control. Information implicit in the waveforms transmitted include the power level of the signal, the signal quality as perceived by the receiver, and information used in tracking both carrier frequency offset and symbol timing error for synchronization between the transmitter and receiver. The system 10 contains considerable operational flexibility both from the standpoint of network features and mobile terminal capabilities. The gateway 16 is a conventional gateway as understood in the art, which includes a mobile switching center (MSC), base station controllers (BSCs), base transceiver stations (BTS), and radio frequency units. As is understood by those skilled in the art, the MSC allows communications with the public switch telephone network or other mobile switching centers. The MSC is connected preferably with an A-interface such as a standard E 1 or E 3 line with the BSC. The BSC is then connected through a communications channel such as a T 1 line to one or more BTSs which may communicate via radio frequency (RF) communications to the access terminal 12 . Telephony communications may be originated with the access terminal 12 by transmitting initialization data to the satellite 14 of the space segment over a control channel which then communicates down to the gateway 16 . The control channel is transmitted over a time slot within a frequency assigned to the spot beam 20 having a coverage area surrounding the access terminal 12 . At the gateway 16 , the call is transmitted via a radio frequency channel to the BTS assigned to the spot beam 20 servicing the access terminal 12 . From the BTS the call is routed to the BSC and then to the MSC, from which the call is routed to either the PSTN or another MSC. Thereafter, a communications channel is established through the entire gateway 16 and a subscriber using the access terminal 12 may communicate over the established communications channel. Calls may also originate from either the PSTN or a GSM cellular network by entering the gateway 16 at the MSC which routes information to the BSC for paging the access terminal 12 via the appropriate BTS. After the access terminal 12 responds to the page from the BTS, a communications channel is then established. The access terminal 12 as shown in FIG. 2 includes a satellite module 40 , a satellite antenna 42 , a cellular module 44 , and a user interface module 46 . The satellite module 40 is coupled to the user interface module 46 , the cellular module 44 , and the satellite antenna 42 . Preferably, the satellite antenna 42 is a physically small antenna, such as a helix type antenna. The satellite module 40 includes a modem and TDMA unit 48 , an RF coder and decoder (codec) 50 , a burst transmitter 52 , a receiver 54 , and a transmit or receive (T/R) switch 56 . In the preferred embodiment, the modem 48 is connected to the RF codec 50 , and the RF codec 50 is connected to the burst transmitter 52 and to the receiver 54 . The T/R switch 56 is connected to the burst transmitter 52 , the receiver 54 , and the satellite antenna 42 . Within the satellite module 40 , the modem 48 converts speech or data samples to and from channel symbols using quadrature phase shift key modulation (QPSK). QPSK is preferably performed digitally by an application-specific integrated circuit or alternatively on a commercial available digital signal processor. The RF codec 50 converts channel symbols from the modem 48 into baseband I and Q signals that are transmitted to the burst transmitter 52 . In the receive direction, the RF codec 50 processes an IF signal 53 from the receiver 54 for input to the modem 48 . The burst transmitter 52 converts the I and Q signals from the RF codec 50 up to a desired frequency, preferably an L-band frequency, for transmission by the first antenna 42 . The receiver 54 converts a received L-band signal from the first antenna 42 into the IF signal 53 sent to the RF codec 50 . The T/R switch 56 allows the access terminal 12 to either transmit data or receive data. The access terminal 12 also includes a synthesizer 58 that provides a fixed local oscillator (LO) signal for the RF codec 50 . The synthesizer 58 includes a variable local oscillator for channel tuning within the satellite module 40 and generates data clock signals for the modem 48 . Both the fixed local oscillator and the variable local oscillator within the synthesizer 58 may be adjusted based on commands from either the gateway 16 or from another access terminal 12 . In the preferred embodiment, the synthesizer 58 is connected to the receiver 54 and to the cellular module 44 . The user interface module 46 includes an audio and codec unit 59 , a voice processing unit 60 , a controller 62 , an input/output (I/O) interface 64 , and a memory 66 . Preferably, each element within the user interface module 46 communicates with the other user interface elements. The voice processing unit 60 includes a voice transcoder that performs source coding to compress the digital 64 Kb/s PCM signal. Specifically, an encoder running on a programmable digital signal processor, such as a low delay CELP encoder, compresses the 64 Kb/s PCM signal into approximately a 3.6 Kb/s encoded signal. Alternatively, the encoder may be a multiband excited (MBE) type 3.6 Kb/s encoder that is well known to those skilled in the art. The controller 62 preferably provides a multitasking firmware environment for monitoring and controlling the mobile terminal hardware. The controller 62 may occupy the same processor as the voice transcoder or may optionally be disposed on a separate processor. Preferably, the controller 62 includes an I/O interface 64 that provides a communication interface with a user. The I/O interface 64 includes a keypad for data entry such as a phone number, a display, a data port for digital communication such as a facsimile transmission, and a smart card interface as specified for GSM. The cellular module 44 allows the access terminal 12 to communicate with a cellular system over a second antenna 61 . The second antenna is a linearly polarized whip meeting cellular system standards and the cellular module 44 uses standard components, such as a GSM chip set, known to those skilled in the art. Preferably, the access terminal 12 operates in a first mode where the access terminal 12 functions as a conventional cellular phone. In a second mode, the access terminal 12 preferably operates so that the access terminal 12 communicates with the satellite 14 . A battery 68 is provided for portable operation of the access terminal 12 . The preferred access terminal 12 has many advantages. For example, the access terminal 12 provides dual-mode operation, either cellular or satellite. Also, the access terminal 12 is mobile and provides high quality digital voice. Further, the access terminal 12 allows for paging and messaging, transmission at a 2400 or 4800 bps data rate via the data port, and provides a convenient cellular-like interface. Also, the access terminal 12 may transmit on a single channel using a single time slot within a carrier signal allowing many other access terminals 12 to transmit over the same carrier. Thus, the access terminal 12 efficiently transmits over L-band spot beam 20 frequency resources. The following description relates the requirements to individual design aspects of the keep-alive bursts. Note that the specific implementation defined centers around a framing design with the following features. Note that this burst arrangement is similar to that used in the Geosynchronous Earth Orbit Mobile system, but that the durations etc. have been selected to simplify the explanation while retaining the essential issues (i.e., active voice is transmitted in “traffic” bursts.) Traffic bursts are transmitted once every 40 mS and are 5 mS in duration. This 5 mS period is referred to as a slot, and the 40 mS period is a frame. Traffic bursts are transmitted using Coherent-QPSK modulation. One hundred symbols are transmitted in each traffic burst, with additional time within the 5 mS slot duration for waveform ramping, and guard time. FIG. 3 shows a KAB structure timing diagram having content and structure simultaneously satisfying the requirements for voice communications, as set forth in the following table. Requirement Implementation Approach Data transmission for voice 100 bps, requiring 4 bits per frame background sounds Data transmission for power 100 bps, requiring 4 bits perframe control Insensitivity to poor calibration Transmission of KAB's occurs at the of the linearity of power same power level as the traffic. That amplifiers is, power savings arise due to a reduction in the duration of trans- missions, not instantaneous power. Bursts must be very short. Synchronization or training infor- mation cannot be lengthy. The key implication of this is that coherent modulation cannot be supported (efficiently). Equal or better communications Differential Binary Phase Shift Keying performance (Bit Error Rates) (DBPSK) provides suitable perfor- than that achieved with traffic. mance. Approximately 2.5 dB is lost in performance, while 3 dB is gained in Energy-per-Bit. Hence, a slight performance improvement (˜0.5 dB) arises. Support for tracking of Carrier Short bursts provide very weak refer- Frequency Offset by the ences for frequency estimation. receiver. Hence, KAB's consist of two short bursts, separated in time to ensure good frequency estimation without ambiguity. Transmission of the two short bursts must be coherently related. Support for tracking of Symbol Timing estimation is relatively easy Timing by the receiver (compared with frequency). Ongoing transmission of short bursts is sufficient. Minimal delay in transmission of Transmit data once every frame. power control information. The contents of the keep-alive bursts include: 1. 4 bits (symbols) of power control information; 2. 4 bits of background noise information; and 3. 2 differential reference symbols (one per burst), generating a total of 10 transmitted symbols, spread equally over the two bursts. The separation between the bursts should be about half the length of the traffic bursts. Selection of this time depends on the following factors: Longer burst separations improve the accuracy of frequency error estimates; and shorter burst separations ensure that probability of ambiguity in the estimate of the phase difference between the two bursts is reduced. For example, with a 100 Hz error, and 2.5 mS between bursts, a phase change of 90° will occur between the bursts. Assuming that the phase relationship between the transmitted differential reference symbols is known, and that the Signal-to-Noise Ratio is reasonable, the 90° phase change is unlikely to get mistaken for the −270° phase change that would accompany a −300 Hz frequency error. The burst separation should permit location of the bursts to enable even distribution of power in time, as viewed by the satellite. The “Adjustable Time Offset” is randomly assigned to each terminal, such that the keep-alive bursts are approximately evenly spread in time when the cumulative power reaches the satellite. If the keep-alive bursts are fixed in time, then all carriers transmitting keep-alive bursts during a particular time slot will always be transmitting during the same instant and during that instant the power required of the satellite transponder will be higher than desired because every single carrier (both those transmitting voice bursts and those transmitting KABs) will be on simultaneously. There may be no benefit from the voice deactivation during that instant. Therefore, the KABs are distributed over time so that not every carrier transmitting KABs will transmit simultaneously. The randomly-assigned “Adjustable Time Offset” remains fixed during a call. Over all terminals, the offset is uniformly distributed between about 0 and 45 symbol periods. For this example, five periods would be an appropriate quantization of this setting. In some specific applications (differing number of bits in the keep-alive burst or different number of bits in the traffic burst), the numbers of bits do not divide evenly. For example, if the number of traffic bits were 99 instead of 100 in the previous example, there would be seven unique potential locations for the KABs (with Adjustable Time Offsets of 0, 5, 10, 15, 20, 25, 30, 35, and 40 bits; the offset of 45 bits would not allow the second KAB to fit within the traffic burst allocation). In this case, there will be 4 bits in the middle and at the end of the traffic burst allocation which will not have anything transmitted. Therefore, it is desired that the method used for distributing the KABs accommodate these possibilities. Some useful ways are: 1. Use Adjustable Time Offset values of 0, 1, 2, . . . , 44. This solution evenly distributes the KAB energy throughout the assigned time slots throughout the system, except that the first and last 4 bit frames have increasing/decreasing amounts of power (since there are five ways to assign the KAB offsets in the middle but only one way to assign them at the beginning and end). 2. Distribute the extra bits between the bursts as in these possible Adjustable Time Offsets as illustrated in FIG. 4, wherein the X's indicate possible locations of KAB burst energy, i.e., each X represents one bit. This distribution is even more uniformly spread than for option 1 above. Locations 0-3 are occupied {fraction (9/10)}th of the time; location 4 100% of the time, locations 5 through 8 {fraction (9/10)}ths of the time, etc. 3. Many other arrangements may be made that provide even more uniform distributions, such as distributing the 4 extra bits in all combinations of 1, 2, 3, and 4 extra bits in a row, scattered among the bursts. 4. The preceding approaches can use known, but varying, time offsets. For example, a pseudo-random sequence could be applied. The position of the transmission of the first KAB is derived from a 16 bit pseudo-random number. The eight least significant digits of the frame number (FN) of the original RACH transmitted by the AT 12 comprise the eight most significant bits of this pseudo-random number and eight least significant digits of either the telephone number called for mobile originated calls or the TMSI (IMSI) for all other cases (call termination, registration, detach, etc . . . ) include the eight least significant bits of this pseudo-random number. The resulting 16 bit number modulo 35 and modulo 54 points to the start of the transmission of the first KAB respectively for TCH 2 and TCH 3 . For TCH 4 , TCH 6 and TCH 9 the pointer is derived using the 16 bit number respectively modulo 70 , 108 , and 162 . The first KAB pointer is returned by the gateway in the Immediate Assignment Message. The pointer to the second KAB is implemented by the gateway and the AT 12 according to the traffic channel size. The pointer to the first KAB and the separation are selected to optimize toward a uniform power distribution per symbol position over time. Excluding duplication, each symbol slot except for the first and the last 4 next to the guard times, may be selected 5 times. FIG. 5 depicts the usage for the beginning of the burst. This is the same at the end. The keep-alive burst symbol position usage described herein provides a power distribution over time as illustrated in FIG. 6 . The power distribution is typically flat over the traffic time slots except for the symbol slot at the center. In the middle, the separation from the first pointer to the last pointer is illustrated in FIG. 7, which shows symbol utilization in the middle of channel TCH 2 . Thus, an elevated power usage over time is shown for the symbol position employed in the power distribution as illustrated in FIG. 8 . The same type of situation does not occur for channel TCH 3 . The derivatives have multiple power distribution symbol bumps in the half boundaries of the basic traffic channels (TCH 2 and TCH 3 ). FIG. 9 is a flow chart illustrating the determination of keep-alive burst positions during the course of voice communications over a traffic channel, and particularly the positioning of keep-alive bursts during periods of voice inactivity. Initially, the user initiates the call via access terminal 12 by transmitting a random access channel request (RACH) at step 100 . In the terminal to terminal call, the immediate assignment procedure provides that the access terminal 12 which originates the call, sends a channel request on the RACH with the called party number and GPS position. The access terminal 12 then waits for immediate assignment on the access grant channel (AGCH) of the corresponding, control channel (CCCH). Thus, at the same time, the gateway station 16 assigns the keep-alive burst position to the access terminal 12 via the AGCH at step 102 . The access terminal 12 and the gateway station 16 calculate the keep-alive burst positions, herein at least two keep-alive burst positions (SKAB 1 and SKAB 2 ) at step 104 . Thereafter, at step 106 the access terminal 12 uses the calculated keep-alive burst positions, SKAB 1 and SKAB 2 , to determine when to transmit keep alive bursts. At the same time, the gateway station 16 looks for the keep-alive bursts (KABs) at the calculated position. The same calculated positions are used in the opposite direction as well. With reference to FIG. 10, the transmit operation used by the access terminal 12 is illustrated as a program flow chart, wherein step 108 is used to wait for the beginning of a transmit time slot in the described time division multiplex access telephony system. Step 110 then determines whether voice communications is active or inactive. During periods of voice inactivity, step 112 is indicated from step 110 , step 112 causing the access terminal 12 to wait for SKAB 1 . Step 114 then transmits a keep-alive burst, and step 116 waits for the symbol indicating SKAB 2 . Step 118 is then used to transmit the second keep-alive burst, and program flow returns from step 120 to wait for the next frame, and returns the transmit operation to step 108 . Alternatively, if voice communications is active in the time slot, step 110 identifies voice activity and step 122 is used to transmit the voice burst, after which the access terminal 12 waits for the next frame at step 120 and waits for the beginning of the transmit's time slot at step 108 . The above-described transmit operation is illustrated for two keep-alive burst positions during periods of voice inactivity, as shown in FIG. 3 . The gateway station 16 performs a keep-alive burst receive operation as illustrated in the program flow chart of FIG. 11, wherein the gateway station 16 waits for the beginning of a receive time slot at step 124 . At step 126 , the gateway station 16 samples and stores the signal contained in the entire time slot received. The operation performed at step 128 determines if there exists a voice burst, a keep-alive burst, or other in the received time slots. Where a voice burst was received at step 128 , step 130 then demodulates the voice transmission, and the gateway station 16 waits for the next frame at step 134 , from which program flow returns to wait for the beginning of the receive time slot at step 124 . Where a keep-alive burst was received at step 128 , step 132 demodulates the keep-alive burst beginning at positions SKAB 1 and SKAB 2 , and upon completion of the keep-alive burst demodulation, program flow returns via step 134 . If nothing has been received in the receive time slots, a step 128 does not demodulate transmissions, but rather returns to wait for the next frame at step 134 , returning program flow as described above to wait for the beginning of the received time slot at step 124 . It should be appreciated that a wide range of changes and modifications may be made to the preferred embodiments as described herein. Thus, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that the following claims, including all equivalents, are intended to define the scope of the invention.

A system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for destroying of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver.

FIELD OF THE INVENTION [0001] The present invention regards a therapy for renal diseases and the ensuing alterations of the renal function, in particular, even though not exclusively, of the renal diseases which develop in diabetic patients or who have been subjected to a chemotherapy antitumor treatment using a platinum derivative. BACKGROUND OF THE INVENTION [0002] The chronic renal disease and renal failure which derives therefrom are extremely frequent diseases even though under-diagnosed; actually, it is estimated that 17% of the adult population is affected by this disease. [0003] The most frequent renal disease is characterised by damaged renal glomerula. [0004] Renal diseases may be congenital or acquired; in particular the acquired ones may have various etiology: immunologic like the Goodpasture's syndrome, lupus nephritis and immunoglobulin A nephropathy. In the case of the immunologically mediated renal disease, the cause lies in the presence of a strong antigenic stimulus which triggers an immune reaction; dysmetabolic and in particular diabetic nephropathy, one of the most common causes of chronic renal disease. The prevalence is of 20-30% in patients suffering from type 1 diabetes and about 10% of the cases in patients suffering from type 2 diabetes. This is an insidious disease in that it is characterised by a particularly slow occurrence (up to 20-30 years from the occurrence of diabetes) and it is practically asymptomatic over a long period of time; it initially occurs through a microalbuminuria (an amount of albumin in the urine comprised between 30 and 300 mg/l) which slowly develops into macroalbuminuria indicating a manifest nephropathy (an amount of albumin in the urine exceeding 300 mg/l, up to reaching values of 3 g within 24 hours); hemodynamic, due to arterial hypertension. An alteration in the pressure mechanisms of the renal blood flow leads, over time, to a reduction of the renal filtering capacity; ischemic. Renal ischemia is the most frequent pathogenic event involved in acute renal disease and in the ensuing tubular necrosis, both in native and transplanted kidneys; toxic. Most of the clinically important drugs (cytotoxic agents, chemotherapy agents, nonsteroidal anti-inflammatory drugs, corticosteroid therapies, etc) and various chemical products (such as radiologic contrast media, solvents, etc) produce nephrotoxicities capable of very frequently causing inflammation at the renal parenchymal level and functional insufficiency both transitory and chronic. [0010] Even in veterinary medicine, renal diseases bound to develop into chronic renal disease constitute an important clinical category, representing the second cause of death in dogs, after diseases of tumour origin, and the first cause of death of the aged cats. From an etiologic point of view, the causes that determine the loss, progressive and irreversible, of the functionality of the nephrons in small animals were precisely classified in (Squires et al, 1998) in: Degenerative: chronic interstitial nephritis; renal infarction Autoimmune: Anti-GEM glomerulonephritis Metabolic: diabetes; hyperthyroidism (cats); hypercalcemia Neoplastic: renal lymphomas and carcinomas Idiopathic: amyloidosis; idiopathic glomerulonephritis Infective: bacterial pyelonephritis; Lyme nephropathy (Borreliosis) Immune-mediated: immune-complex glomerulonephritis Toxic: nephrotoxic drugs (e.g. cisplatin, aminoglycosides, NSAIDs) Traumatic: rupture of bladder and urethra. [0020] In any case, regardless of the etiology, in all acquired renal diseases, both in humans and animals, there is an activation of the inflammatory processes primarily aimed at countering the harmful events but which may become the cause of renal glomerulosclerosis and of tubulointerstitial fibrosis capable of determining the development of chronic renal disease up to the pre-End stage (pre-End Stage Renal Disease) wherein most of the nephrons are destroyed. One of the two main objectives of nephrology is, first and foremost, that of understanding the mechanism which regulates the passage from an acute renal damage to the chronic fibrotic renal disease given that, once the fibrogenesis has started it might be very difficult, currently, to intervene on the fibrotic process; in any case, the objective of stopping or at least slowing the progression of the chronic renal disease remains extremely important considering that such disease also constitutes an important risk factor for cardiovascular diseases. Regarding this, currently there are several studies aimed at accurately understanding the most significant mechanisms of occurrence, with the aim of preventing the phenomena that determines the irreversibility of the disease. Among these phenomena, the most significant one is that which induces tubulointerstitial fibrosis considered the main cause of the chronic renal disease; fibrosis causes an excessive accumulation of extracellular type, mainly made up collagen, and it is usually accompanied by a progressive loss of renal function when the normal tissue is replaced by a cicatricial tissue. One of the most currently studied phenomena is constituted by processes of controlling the genesis of mio-fibroblasts and by the role played by these cells in the formation of the fibrotic cicatricial tissue. In particular such studies try to understand the reason why a reparative phenomenon usually provided for by the tissue, like the renal one, continuously subjected to an extensive amount of novae, may at one point determine an excessive increase of the extracellular matrix and thus a tubulointerstitial fibrosis. Particular attention is currently paid to the genesis of mio-fibroblasts both starting from tubular-epithelial cells and from endothelial cells through a process of phenotypic transformation from epithelial to mesenchymal, potently stimulated by the TGF-1β (Transforming Growth Factor). Actually, the TGF-1βexpression constantly increases in the renal tubular epithelium during an active process of fibrogenesis. In animal models of renal damage, the dose in the renal tubular epithelium of the TGF-1β is considered an interesting indication of the state of activation of fibrogenesis and, hence the state of functional alteration induced by the renal disease. [0021] Regardless of the extensive new information regarding the pathogenic mechanisms involved in the development of renal diseases, satisfactory therapeutic solutions for controlling these conditions are yet to be discovered. [0022] Palmitoylethanolamide (PEA) is the parent of a family of N-acyl amides called Aliamides: a class of endogenous lipid molecules capable of normalizing the activity of immune cells through a local antagonist mechanism. The analgesic effects, instead, are related to a normalisation of the controlled release of trophic factors like NGF which, if present in excess in the tissues, make the neuronal structures hypersensitive and hyperexcitable, with the occurrence of hyperalgesia and allodynia. From a clinical point of view, the oral uptake of products containing PEA is capable of improving the neuropathic symptomotology related to the peripheral neuropathy also promoting the functional recovery of the motor conduction velocity. PEA, at experimental level, is also efficient in dysmetabolic neuropathies, in particular administration thereof to animals made diabetic with streptozotocin eliminates allodynia and induces a partial recovery of the body weight and an increase of the insulin blood levels. These animals also reveal low over-production of blood free radicals and the levels of NGF in the sciatic nerve. [0023] Analogously to the PEA, given N-acyl amides, generally formed from monoethanolamine and dicarboxylic fatty acids, saturated and unsaturated, per se non-physiologic but equally capable of forming, during catabolism, substances physiologically present in the organism of mammals, thus not determining accumulation and/or toxicity of any kind, proved capable of determining pharmacological effects similar to the parent PEA. SUMMARY OF THE INVENTION [0024] Now, we have surprisingly discovered that some molecules belonging to the class of the amides between an amino alcohol and a mono- or dicarboxylic acid are active in the treatment of renal diseases. In particular, it was observed that palmitoylethanolamide (PEA) and diethanolamide of fumaric acid, a monounsaturated dicarboxylic fatty acid normally present in the organism of mammals, revealed a considerable activity with respect to said diseases. [0025] Thus, a first object of the present invention is constituted by a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine, or mixtures thereof, for use in the treatment of renal diseases, in particular but not exclusively renal diseases caused by dysmetabolic diseases or by toxic agents. [0026] A further object of the present invention is represented by palmitoylethanolamide (PEA) for use in the treatment of renal diseases, wherein PEA is preferably in micronized form or in ultra-micronized form. [0027] A further object of the present invention is constituted by PEA for use in the treatment of renal diseases, wherein said PEA is administered orally. [0028] A further object of the present invention is constituted by diethanolamide of fumaric acid for use in the treatment of renal diseases, in aqueous solution. DETAILED DESCRIPTION OF THE INVENTION [0029] The present invention is based on the surprising discovery that the exogenous administration of a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine and in particular oral administration of Palmitoylethanolamide preferably in micronized form (PEAm) or in ultra-micronized form (PEAum) and/or of diethanolamide of fumaric acid, administered preferably in solubilised form in suitable aqueous media, is capable of substantially improving the renal function in a mammal affected by the renal disease, with particular reference to diabetic nephropathy and nephropathy from antitumor agents. The present inventors also discovered that the improvement of the renal function is associated to a lower expression of the TGF-1β considered a considerable indication of the fibrogenesis in progress. The improvement of the renal function is also confirmed in patients affected by inflammatory nephropathy and diabetic nephropathy. [0030] In an embodiment of the invention, said C12-C20 monocarboxylic acid, saturated or monounsaturated, is selected from among palmitic acid, stearic acid and oleic acid. [0031] In an embodiment of the invention, said C4-C14 dicarboxylic acid, saturated or monounsaturated, is selected from among fumaric acid, azelaic acid and trans-traumatic acid. [0032] Palmitoylethanolamide is a commercial product, which can be prepared through conventional methods, well known to a man skilled in the art, such as those that provide for the reaction between ethanolamine or serine, possibly in protected form, and said mono- or dicarboxylic acid in suitable conditions of condensation, which may also provide for the use of condensing agents. [0033] The term “PEA in micronized form” or “PEAm” is used to indicate palmitoylethanolamide in which at least 94% or at least 95% or about 96% of the particles has a dimension smaller than 10 microns and preferably at least 77% or at least 78% or about 80% of the particles has a dimension smaller than 6 microns. PEAm may be prepared according to the disclosure of the European patent n° EP 1 207 870 B1. [0034] The term “PEA in ultra-micronized form” or “PEAum” is used to indicate palmitoylethanolamide in which at least 97% or at least 98% or at least 99% or about 99.9% of the particles has dimensions smaller than 6 microns and preferably at least 57% or at least 58% or at least 59% or about 59.6% of the particles has dimensions smaller than 2 microns. PEAum may be prepared according to the disclosure of the patent application n° PCT/IT2009/000399. [0035] Diethanolamide of fumaric acid may be prepared by synthesis according to the disclosure of Example 10 of U.S. Pat. No. 5,618,842. [0036] Thus, the present invention regards a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine, or mixtures thereof, for use in the treatment of renal diseases, in particular but not exclusively renal diseases caused by dysmetabolic diseases or by toxic agents. [0037] In an embodiment said mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated is PEA or diethanolamide of fumaric acid. [0038] In an embodiment, PEA is used in micronized form (PEAm). [0039] In a different embodiment, PEA is used in ultra-micronized form (PEAum), alone or mixed with PEAm. [0040] In an embodiment, diethanolamide of fumaric acid is used in solubilised form in a suitable aqueous solvent. [0041] Pharmacological Activity of the Compounds of the Invention [0042] Occurrence of Renal Damage after Administration of Streptozootocin to Mice [0043] The model of streptozootocin in mice represents a classic and known model of hyperglycemia capable of inducing a progressive renal damage into the animal leading to the renal disease with clear alterations of the characteristic parameters. [0044] The model applied is as follows: male mice C57BL6/J were kept under standard conditions of care. Diabetes was induced into 8-weeks old mice and with an average weight of about 22 g by means of an intraperitoneal injection of streptozotocin in citrate buffer (55 mg/Kg of weight/day) for 5 consecutive days. The control animals were treated in the same conditions using the citrate buffer alone. [0045] Treatments were administered orally, by means of a tube, using both micronized Palmitoylethanolamide—PEAm (10.0 mg/Kg) suspended in a carrier and ultra-micronized palmitoylethanolamide PEAum (10.0 mg/Kg) suspended in a carrier; the results were compared with control animals treated with the carrier alone. A 0.5% carboxymethyl cellulose was used as a carrier. [0046] Diethanolamide of fumaric acid was administered in sterile aqueous saline solution by intraperitoneal injection (10.0 mg/Kg); the results were compared with the animals treated with sterile saline solution alone. [0047] Administration of the carrier and of the two different suspensions containing palmitoylethanolamide or of the injection solution containing diethanolamide of fumaric acid, were performed once per day starting from the day of the last administration of Streptozotocin. Prior to sacrifice, the blood was collected from the saphenous vein using a micro syringe to determining, through conventional methods, the levels of glycemia, glycated haemoglobin and creatinine of the serum. [0048] The evaluation of TGF-1β on the renal tissue was administered through the following method: [0000] small pieces of the renal cortex, carefully separated and weighed, were homogenised in Tris-HCl 10 mM buffer at 7.4 pH containing 2M of NaCl, 1 mM PMSF (phenylmethylsulfonyl fluoride, as a protease inhibitor), 1 mM EDTA and 0.01% of Tween 80. The samples were centrifuged at 19,000 rpm for 30 minutes and the supernatant was collected, measured and preserved at −80° C. The evaluation of the TGF-1β was made using the ELISA commercial kit (Quantikine Kit™, Res & Diagn Systems, Minneapolis, USA) and the value expressed in pg/mg of total proteins. The concentration of total proteins was measured using the Bio-Rad commercial test (Hercules, Calif., USA). [0049] The obtained results were gathered in Table 1. [0000] TABLE 1 Diabetic Diabetic animals Diabetic animals treated treated animals Diabetic by i.p. orally Diabetic treated with animals injection with Non- with the animals ultra treated by i.p. diethanolamide diabetic carrier treated with micronized injection with of fumaric acid animals alone micronized PEA - saline solubilised in Examined (10 (10 PEA - PEAm PEAum solution alone saline solution parameter animals) animals) (10 animals) (10 animals) (10 animals) (10 animals) Body weight (g) 27.82 ± 1.18  25.12 ± 1.10 26.52 ± 1.08 26.12 ± 1.21 24.43 ± 1.15 26.22 ± 1.02 Glycemia 122.2 ± 5.62  408.45 ± 33.12 386.12 ± 36.76 380.34 ± 34.16 406.32 ± 33.44 386.19 ± 33.98 (mg/dl) Glycated 4.89 ± 0.05 12.80 ± 0.44 11.32 ± 0.38 11.01 ± 0.18 13.41 ± 0.63 12.12 ± 0.26 haemoglobin % Kidney 6.65 ± 0.04  8.65 ± 0.85  7.85 ± 0.44  7.15 ± 0.38  9.00 ± 0.56  7.02 ± 0.46 weight/body weight Amount of 33.7 340.5 289.4 151.5 315.05 135.7 albumin (26.2-41.5) (182.2-630.3) (166.4-480.6) (71.3-283.8) (201.3-582.4) (94.6-171.4) excreted with urine (18 hrs prior to sacrifice) Concentration of 0.21 ± 0.01  1.11 ± 0.02  0.81 ± 0.01  0.44 ± 0.01  1.51 ± 0.08  0.51 ± 0.03 creatinine in the serum (mg/dl) Level of TGF-1β 7.5 ± 0.8 24.2 ± 5.8 15.0 ± 3.0 10.3 ± 2.5 25.3 ± 4.6 11.7 ± 3.2 (pg/mg) [0050] Occurrence of Renal Damage after Administration of Cisplatin to Mice [0051] Cisplatin, a known and widely used chemotherapy agent, notoriously produces a serious renal damage in 50% of the patients subjected to treatment. Experimentally an animal model is used in mice, in which Cisplatin induces serious nephrotoxicity with ensuing renal disease. The model applied is as follows: male mice C57BL6/J were kept under standard conditions of care. Nephrotoxicity was induced into 8-weeks old mice and with an average weight of about 23 g, by means of an intraperitoneal injection of Cisplatin dihydrochloride in saline solution (20 mg/Kg in one administration). The control animals were treated in the same conditions using the saline solution alone. The animals were sacrificed 72 hrs after treatment with Cisplatin. [0052] 6 treatments were administered orally, one each 12 hrs by means of a tube, using both micronized palmitoylethanolamide—PEAm (10.0 mg/Kg) suspended in a carrier and ultra-micronized palmitoylethanolamide—PEAum (10.0 mg/Kg) suspended in a carrier; the first treatment was carried out 12 hours prior to the administration of the Cisplatin. The results were compared with control animals treated with the carrier alone. A 0.5% carboxymethyl cellulose solution was used as the carrier. [0053] Diethanolamide of fumaric acid was administered in sterile aqueous saline solution by intraperitoneal injection (10.0 mg/Kg) with posology analogous to that of PEA; the results were compared with animals treated with sterile saline solution alone. [0054] Prior to sacrifice, the blood was collected from the saphenous vein using a micro syringe to measure, through conventional methods, the levels of creatinine of the serum. [0055] The level of TGF-1β on the renal tissue was measured through the following method: small pieces of the renal cortex, carefully separated and weighed, were homogenised in Tris-HCl 10 mM buffer at a 7.4 pH containing 2M of NaCl, 1 mM PMSF (phenylmethylsulfonyl fluoride, as a protease inhibitor), 1 mM EDTA and 0.01% of Tween 80. The samples were centrifuged at 19,000 rpm for 30 minutes and the supernatant was collected, measured and preserved at −80° C. The amount of the TGF-1β was measured using the ELISA commercial kit (Quantikine Kit™, Res & Diagn Systems, Minneapolis, USA) and the value expressed in pg/mg of total proteins. The concentration of total proteins was measured using the Bio-Rad commercial test (Hercules, Calif., USA). [0056] The obtained results were gathered in Table 2. [0000] TABLE 2 Animals Animals Animals with with with cisplatin Animals Cisplatin cisplatin treated by i.p. with Animals treated with treated by injection with Cisplatin with Cisplatin ultra i.p. injection diethanolamide Control treated with treated with micronized with saline of fumaric acid animals the carrier micronized PEA - solution solubilised in Examined (10 alone PEA - PEAm PEAum alone saline solution parameter animals) (10 animals) (10 animals) (10 animals) (10 animals) (10 animals) Body weight (g) 26.12 ± 1.11  23.10 ± 1.22  23.58 ± 1.13  24.55 ± 1.09  24.22 ± 1.45  24.15 ± 1.12  Kidney weight/body 6.44 ± 0.03 7.22 ± 0.80 7.85 ± 0.34 6.89 ± 0.42 8.15 ± 0.46 6.58 ± 0.26 weight Amount of albumin 37.4 363.75 270.90 175.9 351.57 181.4 excreted with urine (18 hrs (31.7-44.6) (282.8-735.9) (206.9-405.8) (91.7-260.8) (258.1-623.4) (96.3-225.6) prior to sacrifice) Concentration of 0.22 ± 0.01 1.26 ± 0.05 0.92 ± 0.03 0.48 ± 0.02 1.36 ± 0.02 0.83 ± 0.06 creatinine in the serum (mg/dl) Dose of TGF-1β 8.2 ± 0.7 25.3 ± 6.0  15.8 ± 3.5  9.4 ± 3.2 22.1 ± 4.3  9.1 ± 2.8 (pg/mg) [0057] Effect of Ultra-Micronized Palmitoylethanolamide PEAum in Nephropathic Patients [0058] Palmitoylethanolamide was administered to patients in form of tablets each containing 600 mg of active ingredient in ultra-micronized form; 2 tablets per day (one every 12 hours, after meals) were administered to patients for 60 consecutive days). [0059] Determination of the GRF (Glomerular Filtration Rate) by the creatinine endogenous marker was carried out according to the US National Renal Foundation criteria (K/DOQI clinical practice guidelines for chronic kidney disease, 2002), using the Cockcroft-Gault equation (Cockcroft D. W. et al, 1976). [0060] The results were indicated in Table 3. [0000] TABLE 3 GFR Glomerulal Filtration Rate (Creatinine Glycemia under fasting Clearance) abbr Age Gender Diagnosis T 0 T 60 T 0 T 60 Paz- S.G. 65 F Chronic Inflammatory N.D. N.D. 26.4 44.6 01 nephropathy Paz- S.C. 71 M Chronic Inflammatory N.D. N.D. 21.4 35.2 02 nephropathy Paz- F.S. 62 F Chronic Inflammatory N.D. N.D. 20.7 36.1 03 nephropathy Paz- M.R. 61 M Diabetic nephropathy 210 mg/dl 110 mg/dl 18.9 41.4 04 (Diabetes type 2) compensated compensated with 10 U. with 12 U. ready insulin retard insulin Paz- B.V. 77 F Diabetic nephropathy 240 mg/dl 230 mg/dl 22.4 35.6 05 (Diabetes type 2) compensated compensated with 10 U. with 10 U. ready insulin ready insulin Paz- N.C. 69 F Diabetic nephropathy 280 mg/dl 210 mg/dl 21.8 39.8 06 (Diabetes 2) compensated compensated with 10 U. with 10 U. ready insulin + ready insulin + 20 U. retard 20 U. retard insulin insulin [0061] The results indicated above clearly show that PEA, in particular when administered orally in micronized or ultra-micronized form, may be successfully used in the treatment of renal diseases in a mammal. Also diethanolamide of fumaric acid revealed to be active through intra-peritoneal injection. [0062] The compounds of the invention may thus be used, both for humans and veterinary purposes, in the treatment of renal diseases. [0063] Such diseases are preferably selected from among: Diabetic nephropathy Nephroangiosclerosis Pyelonephrite Polycystic kidney disease (polycystic kidney) Alport syndrome Lesch-Nyham syndrome Goodpasture's syndrome Lupus nephritis Immunoglobulin A nephropathy Tubular necrosis Glomerulonephritis Urethral stenosis Iatrogenous nephropathies (from NSAIDs, from cytotoxic drugs, from Lithium, from antibiotics, from Cyclosporine, etc) Nephropathies from therapeutic radiations Nephropathies of the aged. [0079] The compounds of the invention may thus be formulated for oral, buccal, parenteral, rectal or transdermal administration. [0080] PEA may be preferably formulated for oral administration. [0081] Diethanolamide of fumaric acid may be preferably formulated for oral or injection administration considering the high solubility of such synthetic molecule in water. [0082] For oral administration, the pharmaceutical compositions may be provided, for example, in form of tablets or capsules prepared conventionally with pharmaceutically acceptable excipients such as binding agents (for example pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); bulking agents (such as for example lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (for example magnesium stearate, talc or silica); disintegrants (for example potato starch or sodium starch glycolate); or inhibitor agents (for example lauryl sodium sulfate). The tablets may be coated by means well known in the art. The liquid preparations for oral administration may be, for example, in form of solutions, syrups or suspensions or they may be in form of lyophilised products to be reconstituted, prior to use, with water or other suitable carriers. Such liquid preparations may be prepared through conventional methods with pharmaceutically acceptable additives such as suspension agents (for example sorbitol syrup, cellulose derivatives or edible hydrogenated fats); emulsifying agents (for example lecithin or acacia); non-aqueous carriers (for example almond oil, oily esters, ethylic alcohol or fractionated vegetable oils); and preservatives (for example methyl- or propyl-p-hydroxybenzoates or sorbic acid). The preparation may also suitably contain aromas, colouring agents and sweeteners. [0083] The preparations for oral administration may be formulated suitably to allow the controlled release of the active ingredient. [0084] For buccal administration, the compositions may be in form of tablets formulated conventionally, suitable for absorption at the buccal mucosa level. Typical buccal formulations are tablets for sublingual administration. [0085] The compounds of the invention may be formulated for parenteral administration by injection. The formulations for the injection may be in form of one dose for example in a vial, with an added preservative. The compositions may be in such form as suspensions, solutions or emulsions in oily or aqueous carriers and they may contain formulary agents such as suspension, stabilising and/or dispersion agents. Alternatively, the active ingredient may be in form of powder to be reconstituted, prior to use, with a suitable carrier, for example with sterile water. [0086] Diethanolamide of fumaric acid may be easily formulated in sterile and non-pyrogenic aqueous solutions according to conventional literature of the pharmaceutical industry. [0087] According to the present invention, the compounds of the invention may also be formulated according to rectal compositions such as suppositories or retention enema, for example containing the basic components of common suppositories such as cocoa butter or other glycerides. [0088] In addition to the compositions described previously, the compounds of the invention may also be formulated as deposit preparations. Such long-term formulations may be administered by implantation (for example subcutaneous, transcutaneous or intramuscular) or by intramuscular injection. Thus, for example, the compounds of the invention may be formulated with appropriate polymer or hydrophobic materials (for example in form of an emulsion in a suitable oil) or ionic exchange resins. [0089] According to the present invention the dosage of a compound of the invention, or of mixtures thereof, proposed for administration to a man (with a body weight of about 70 Kg) ranges from 1 mg to 2 g and, preferably from 100 mg to 1 g of the active ingredient per dose unit. The dose unit may be administered, for example, from 1 to 4 times per day. The dosage shall be determined by the selected method of administration. It should be considered that frequent variations of the dose might be required depending on the age and the weight of the patient and also on the seriousness of the clinical condition to be treated. Lastly, the exact dose and method of administration shall be at the discretion of the doctor or veterinarian in question. [0090] The pharmaceutical compositions of the invention may be prepared using conventional methods, such as those described in Remington's Pharmaceutical Sciences Handbook, Mack Pub. Co., N.Y., USA, 17th edition, 1985. [0091] Following are non-exhaustive examples of pharmaceutical compositions according to the invention. Examples of Formulations Example 1 [0092] Each tablet contains: [0000] PEAm mg 300.00 Microcrystalline cellulose mg 78.47 Sodium croscarmellose mg 45.00 Polyvinylpyrrolidone mg 10.00 Stearate magnesium mg 4.00 Polysorbate 80 mg 2.00 Example 2 [0093] Each tablet contains: [0000] PEAum mg 300.00 Microcrystalline cellulose mg 78.47 Sodium croscarmellose mg 45.00 Polyvinylpyrrolidone mg 10.00 Stearate magnesium mg 4.00 Polysorbate 80 mg 2.00 Example 3 [0094] Each tablet contains: [0000] PEAum mg 600.00 Microcrystalline cellulose mg 156.94 Sodium croscarmellose mg 90.00 Polyvinylpyrrolidone mg 20.00 Stearate magnesium mg 8.00 Polysorbate 80 mg 4.00 Example 4 [0095] Each tablet contains: [0000] Diethanolamide of fumaric acid mg 400.00 Microcrystalline cellulose mg 100.00 Sodium croscarmellose mg 80.00 Polyvinylpyrrolidone mg 15.00 Stearate magnesium mg 7.00 Polysorbate 80 mg 6.00 Example 5 [0096] A 5 g dose of oral-dissolvable microgranules, for pediatric use, contains: [0000] PEAum mg 50.00 Non-cariogenic sugar mg 200.00 Pharmaceutically acceptable excipients q.s. to g 5.00 Example 6 [0097] A 5 ml dose of sterile suspension, for pediatric use, contains: [0000] PEAum mg 80.00 Carboxymethyl cellulose mg 25.00 Bi-distilled water q.s. to ml 5.00 Example 7 [0098] A 5 g dose of oral-dissolvable microgranules, contains: [0000] PEAum mg 600.00 Non-cariogenic sugar mg 200.00 Pharmaceutically acceptable excipients q.s. to g 5.00 Example 8 [0099] Each sterile single dose 5 ml two-layer container, contains: [0100] In the aqueous gel: [0000] Hyaluronic acid sodium salt mg 80.00 Bi-distilled water q.s. to ml 2.50 [0101] In the oily gel: [0000] PEAum mg 600.00 Monostearate glyceryl (Geleol) mg 40.00 vegetable oil q.s. to ml 2.50 Example 9 [0102] Each soft gelatin capsule, for veterinarian use (dog and cat), contains: [0000] PEAum mg 100.00 Pharmaceutically acceptable oily excipients mg 300.00 Example 10 [0103] A 2 ml glass vial contains: [0000] Diethanolamide of fumaric acid mg 100.00 Sterile saline solution q.s. to ml 2.0 Example 11 [0104] A 4 ml lyophilized glass vial contains: [0000] Diethanolamide of fumaric acid mg 200.00 Glycocol mg 85.00 [0105] A 4 ml solvent vial contains: [0000] Sterile saline solution ml 4.0 ml

A therapy for renal diseases, in particular renal diseases which develop in diabetic patients or patients who have been subjected to a treatment with an antitumor chemotherapy such as a platinum derivative and more generally cytotoxic drugs at renal level for treating of neoplastic diseases. More particularly, the present invention relates to palmitoylethanolamide and diethanolamide of fumaric acid for use in the treatment of renal diseases, in particular those caused by dysmetabolic diseases or by toxic or chemotherapy agents, such as platinum derivatives. Palmitoylethanolamide is used preferably in micronized or ultra-micronized form. Diethanolamide of fumaric acid is used preferably in aqueous solution.

BACKGROUND OF THE INVENTION THIS invention relates to a floodlight radar system for detecting and locating moving targets in three dimensions. When a radar system with the capability to rapidly detect and locate fast-moving targets in three dimensions anywhere in the search volume is required, a floodlight radar is an appropriate choice. Without scanning its beam (either mechanically or electronically), a floodlight radar transmitter continuously illuminates the full search volume by means of a single wide beam antenna. Detection and location of targets in three dimensions is accomplished by appropriately processing the signals received with multiple receive antennas. Floodlight radars, as described by W Wirth, Radar techniques using array antennas, IEE, 2001, pp. 419-447, have a long legacy. The first operational air-warning system, the Chain Home network built in Britain before the second world war, was a pulsed floodlight system described in British patent GB 593 017 of R Watt. The floodlight principle is also known under other names, such as Array Signal Processing (ASP)—see A. Rudge, K. Milne, A. Olver, and P. Knight, Eds., The Handbook of Antenna Design, Volume 2, Peter Peregrinus, London, U.K., 1983, pp. 330-456. In a floodlight radar, the transmitter “floods” the search volume with electromagnetic waves radiated from the transmit antenna. This is in contrast to a scanned radar, where an antenna directs a scanned pencil or fan beam to one or more small parts of the search volume at any one instant. The floodlight radar therefore simultaneously illuminates all targets in the scan volume at all times. The radiation patterns of the individual antennas of the multiple-channel receiver also cover the complete search volume. The antenna system is often referred to as a staring array. These characteristics of a floodlight radar are the keys to the rapid detection of fast-moving targets anywhere in the search volume. The receive antennas can either be arranged as a densely or sparsely packed phased array forming multiple simultaneous beams, as described by F. Athley, C. Engdahl, and P. Sunnergren, “On radar detection and direction finding using sparse arrays,” Aerospace and Electronic Systems, IEEE Transactions on, vol. 43, no. 4, pp. 1319-1333, October 2007, or as a sparsely packed interferometer array. The vertical and horizontal dimensions of the array determine the accuracy with which elevation and azimuth angles of arrival can be estimated. The densely packed array has the advantage that simultaneous beams covering the full search volume can be formed by means of ASP, with each beam providing a high antenna gain on receive. It is, however, a complex and costly system. A radar with a square array with dimensions of 5 wavelengths on a side covering a search volume of a quarter hemisphere will typically use a 64 channel receiver and a 64 channel signal processor. The sparsely packed array has the advantage that simultaneous beams covering the full search volume can be formed by means of ASP, with each beam providing a high antenna gain on receive, but has the disadvantage that grating lobes are also formed. Various techniques have been devised to identify and eliminate returns from targets in grating lobes as described in U.S. Pat. No. 7,692,575 of Nishimura. The sparse interferometer receive array does not form beams. It has the advantage of a lower hardware count for a given accuracy of location, but suffers the disadvantage of angular ambiguities, where targets at different locations can produce similar antenna responses. It requires special measures to resolve these ambiguities, one of which is to use overlapping high gain antennas, but this severely limits the search volume. The sparse array with wide-beam radiators has much lower directivity than the densely packed array. To overcome the disadvantage of low gain, the transmitter power must be increased with respect to that needed for a densely packed receive array. Conventional single-frequency direction-finder technology to resolve angular ambiguities is well-known, but requires at least five antennas arranged in two dimensions to resolve angular ambiguities in azimuth and elevation. See E. Jacobs and E. Ralston, “Ambiguity resolution in interferometry,” Aerospace and Electronic Systems, IEEE Transactions on, vol. AES-17, pp. 766-780, 1981. It is an object of the invention to provide a floodlight radar system that overcomes at least some of the above mentioned problems and is suitable for detecting and locating moving targets in three dimensions. SUMMARY OF THE INVENTION According to the invention there is provided a floodlight radar system including: a transmitter arranged to generate output waveforms at first and second centre frequencies; at least one transmit antenna configured to illuminate a search volume constantly at the first and second centre frequencies; a sparse array of receive antennas arranged in a common plane and configured to monitor the search volume constantly; a receive circuit arranged to extract target position information from return signals received by each antenna; and a signal processor circuit arranged to resolve ambiguities in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences at the first and second frequencies, to calculate azimuth, elevation, range and velocity of a target identified in the search volume. The sparse array of receive antennas preferably comprises at least one set of three receive antennas. The sparse array of receive antennas may comprise two sets of three receive antennas, one set for each centre frequency. The three receive antennas may be arranged at the vertices of an equilateral triangle. The spacing between adjacent antennas may be indicated by the expression s=kλ, where s is the spacing, λ is the wavelength at the operating frequency of the antennas and k is a value larger than 1. Preferably, k has a value of approximately between 1 and 5. In one example embodiment, k may have a value of approximately 5. In another example embodiment, k may have a value of approximately 2.5. In yet a further example embodiment, k may have a value of 3. The transmitter may be arranged to produce a modulated continuous waveform or alternatively to produce a pulsed waveform. Preferably, the transmitter is arranged to produce a continuous wave waveform. The transmitter may be arranged to generate output waveforms at the first and second centre frequencies alternately. Instead, the transmitter may be arranged to generate output waveforms at the first and second centre frequencies simultaneously. In the first case, each receive antenna may have a single receive channel capable of processing return signals at one or both centre frequencies alternately. In the latter case, each receive antenna may have an associated pair of receive channels for the processing of return signals at the first and second centre frequencies simultaneously. Alternatively, when using separate receive arrays for each frequency, each receive antenna may have a single receive channel for the processing of return signals at either the first or second centre frequency. The signal processor is preferably arranged to sample the return signals from each antenna at each of the two frequencies in the time domain. In the case of a pulse modulated waveform, each sample, after pulse compression if required, represents a range bin. In the case of a continuous wave waveform, the signal processor preferably calculates the discrete Fourier spectrum of the signal, where each discrete component of the transform represents a range bin. The signal processor may calculate discrete Doppler spectra for each range bin from a large number of observations. The signal processor is preferably arranged to detect targets by comparing the Doppler spectra for each range bin to the noise in the spectra when no target is present. The signal processor may be arranged to accurately interpolate the range of the target by comparing amplitude returns from the target in adjacent range bins. The signal processor may be arranged to accurately interpolate the radial velocity of the target by comparing amplitude returns from the target in adjacent Doppler bins. Each detected target is preferably associated with a track according to its range and velocity information. The signal processor is preferably arranged to compare the phase returns of each detected target from each of the antennas. The respective phase differences are used to determine the angular location of each target in azimuth and elevation. The signal processor is preferably arranged to resolve angular ambiguities resulting from the wide antenna spacing by comparing the phase differences between measurements of the same target at the two centre frequencies. The signal processor may be arranged to use redundant information gained from the receiver channels to estimate and indicate the quality of the angular measurement. The signal processor may be arranged to distinguish between inbound, outbound and other ambiguous velocities by comparing the Doppler spectra of the target at the two centre frequencies. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the configuration of a sparse receive array, consisting of three widely spaced antennas, forming part of a floodlight radar system according to the invention; FIG. 2 is a partially cut away pictorial view of a typical antenna element used in the receive array and as a transmit antenna, which will provide coverage over more than an eighth of a hemisphere; FIG. 3 is a schematic diagram which illustrates the principle by which the Direction of Arrival of an incoming plane wave signal is determined along one axis of the antenna array; FIG. 4 is a schematic diagram showing how the target position is arrived at by using a DOA measurement along one axis of the antenna array; FIG. 5 is a schematic diagram showing how the 3D target position is arrived at by using DOA measurements along the three axes of the antenna array; FIG. 6 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with multiplexed receive channels; FIG. 7 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with simultaneous receive channels; FIG. 8 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with separate receive antenna arrays having separate receive channels; FIG. 9 is a block diagram of a signal processor used in conjunction with the transceiver of FIGS. 7 and 8 ; FIG. 10 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a radar that determines the trajectories of targets such as cricket balls and projectiles; FIG. 11 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a gap-filler radar in a wind-farm; and FIG. 12 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a sensor for an armoured vehicle protection system. DESCRIPTION OF EMBODIMENTS The system described herein is a unique floodlight radar with a sparse interferometer receive array using only three receive antennas, that resolves target angular ambiguities in a spherical coordinate system by means of frequency diversity. The receive antennas are arranged in two dimensions and ambiguity resolution is typically accomplished by taking measurements at two frequencies. The radar also assesses the quality of its measurements and identifies suspect measurements that were degraded due to noise or propagation anomalies such as multipath. The Receive Array and the Principle of Ambiguity Resolution The receive array of the radar system described herein is at the core of the system concept and is shown schematically in FIG. 1 , where a receive antenna 10 , 12 , 14 is placed at each vertex or corner of an equilateral triangle. This is not the only possible arrangement of the antennas. They could, for instance, also be arranged at the vertices or corners of a right-angled triangle or, in general, at the corners of an irregular triangle. The antennas are spaced several wavelengths apart, at a spacing s=kλ. Preferably, k is greater than 1 and most preferably falls in the range 4 to 7. A typical spacing for the equilateral arrangement is five wavelengths, or s=5λ (i.e. a value of k of approximately 5). The three receive antennas for each centre frequency are preferably identical, a typical implementation of one such antenna being shown in FIG. 2 . The illustrated antenna has a central circular waveguide feed 16 and a dielectric lens 18 , with a peripheral isolation choke 20 . A fourth similar antenna is used as a transmit antenna. This could either be a separate antenna or one of the receive antennas could double for this purpose. An array as shown in FIG. 1 can be used to determine the direction of arrival (DOA) of an incoming signal, according to the principle shown in FIG. 3 . Let a plane wave varying sinusoidally with time and emanating from a source far away from the antenna array impinge upon the array from a direction θ with respect to a line perpendicular to the line connecting the phase centres of two identical antennas. Depending on the magnitude of the angle θ, there will be a path length difference kλsin(θ) from the source to the 2 nd antenna 12 with respect to the path length from the source to the 1 st antenna 10 . The instantaneous phase angle of the electric field vector is a function of time and distance travelled according to the equation E ⁡ ( t , ς ) = E ⁡ ( ς ) ⁢ cos ⁡ ( ϕ ⁡ ( t , ζ ) ) = E ⁡ ( ζ ) ⁢ cos ⁡ ( ω ⁢ ⁢ t - 2 ⁢ π ⁢ λ ⁢ ζ + ϕ 0 ) . In this equation, ζ is the distance travelled in the direction of propagation, E(ζ) is the peak magnitude of the electrical field vector, ω=2πf is the frequency in radians/second for a wave oscillating with a frequency f Hz, λ is the wavelength of the wave, given by λ = 2 ⁢ π ⁢ ⁢ c ω = c f where c is the velocity of propagation and φ 0 is the instantaneous phase angle at time t=0 and position ζ=0. There will consequently at any given instant be a difference in the phase angles of the signals emanating from the two antennas, given by Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 = ϕ 1 ⁡ ( t , ζ 1 ) - ϕ 2 ⁡ ( t , ζ 2 ) = 2 ⁢ π λ ⁢ ( ζ 2 - ζ 1 ) = 2 ⁢ k ⁢ ⁢ π ⁢ ⁢ sin ⁡ ( θ ) , where subscript 1 refers to the 1 st antenna 10 and subscript 2 refers to the 2 nd antenna 12 . It is convenient to substitute a new variable u for the function sin(θ), so that Δφ u12 =2kπu. The variable u has a range [−1≦u≦1]. All angles are measured modulo 2π, in the range [−π<φ≦π]. Therefore, if k>0.5, Δφ u12 can fall outside the measurable range and wraps back to a measured phase difference Δφ m12 =Δφ u12 −2 πp, where p is, in general, an unknown positive or negative integer. As a consequence, the determination of u and eventually θ from a measurement Δφ m12 is ambiguous. For the sparse array considered here, with k of the order of 5, Δφ m12 can wrap up to four times when [ - π 2 < θ < π 2 ] . The true phase difference must therefore be written as Δφ u12 =2 kπu=Δφ m12 +2 πp, where p is unknown. For k=5, p takes on integer values in the range [−2≦p≦2]. For an unambiguous determination of the arrival angle θ, some means must be found to determine p. In the radar system described here, p is determined by repeating the phase difference measurement at a second frequency. See M. Skolnik, “Resolution of angular ambiguities in radar array antennas with widely-spaced elements and grating lobes,” Antennas and Propagation, IRE Transactions on, vol. 10, no. 3, pp. 351-352, May 1962. The author describes the use of measurements at two frequencies to identify and eliminate echoes from targets in grating lobes of a scanning radar with a sparse array antenna. This in effect changes the electrical antenna spacing. With subscripts a and b referring to frequency a and frequency b, we have k a λ a =k b λ b =s Δφ u12a =2 πk a u=Δφ m12a +2 πp a Δφ u12b =2 πk b u=Δφ m12b +2 πp b Taking the difference of the phase angles yields Δ ⁢ ⁢ ϕ 12 ab = Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 a - Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 b = 2 ⁢ π ⁡ ( k a - k b ) ⁢ u , ⁢ where k a - k b = s λ a - s λ b = s c ⁢ ( f a - f b ) . We note that if | k a −k b |≦½, then [−π≦Δφ 12ab ≦π]. Consequently, if | k a −k b |≦½, φ 12 ab cannot wrap and a determination of u from Δφ 12 ab is unambiguous. (Note that, if the coverage of the antenna is smaller than [ - π 2 < θ < π 2 ] , the range of u decreases and the spacing between the antennas can be increased without introducing ambiguity.) In practice, the determination of u from Δφ 12 ab is not very accurate and also quite noisy. Our approach is therefore to determine a coarse estimate of u from Δφ u12 ab , and then to use this coarse estimate to find an estimate for the correct values of integers p a and p b . We then use these estimates of p a and p b to find a more accurate value of u using Δφ 12 a and Δφ 12 b . Effects such as noise, multipath and interference generally affect the phase angles of the two frequencies in ways that do not follow the defined relationship. This results in the values of u calculated with the two frequencies to differ. When an incorrect value is found for p a and/or p b , the difference between the two values of u can become large. This difference is used as the axis angle input for the confidence parameter that is described below. Note that this difference is calculated for each of the three axes. 3D Target Location We determine the 3-dimensional target location with reference to a coordinate system centred on the antenna array with the x-y axes in the plane of the array, as shown in FIG. 1 . The z-axis is perpendicular to the array in the direction of radiation. To locate a target in three dimensions with the array, first consider the determination of target position from a measurement taken from two antennas. The line connecting the antennas, called an array axis, is inclined at an angle γ to the x axis. The target is detected at range R with its DOA θ determined with respect to the plane perpendicular to the array axis, as shown in FIG. 4 . The target must lie on a circle on the surface of the right circular cone with aperture (π−2θ) with its apex at the centre of the array, at a distance R from the apex. We note that the target must also lie somewhere on the hemisphere with radius R. The intersection of the cone and hemisphere is a semicircle, the plane of which is perpendicular to the array axis and therefore also to the plane of the array. The semicircle intersects the plane of the array at the points (x 1 , y 1 ) and (x 2 , y 2 ), given by x 1 = ⁢ R ⁢ ⁢ cos ⁡ ( γ + θ - π 2 ) = ⁢ R ⁢ ⁢ sin ⁡ ( γ + θ ) y 1 = - R ⁢ ⁢ cos ⁡ ( γ + θ ) ⁢ ⁢ x 2 = - R ⁢ ⁢ sin ⁡ ( γ - θ ) ⁢ ⁢ y 2 = R ⁢ ⁢ cos ⁡ ( γ - θ ) . Solving for the equation of the line connecting (x 1 , y 1 ) and (x 2 , y 2 ), we find that the (x,y) coordinates of the target must lie on the line x = - tan ⁡ ( γ ) ⁢ y + R ⁢ ⁢ sin ⁡ ( θ ) cos ⁡ ( γ ) Two further estimates of location lines in the x-y plane are obtained from measurements along the other two axes of the array, as shown in FIG. 5 . For the specific antenna arrangement of FIG. 1 , where the antennas are placed at the corners of an equilateral triangle, we have the following equations for the three location lines given by the DOA angle θ 12 determined from the signal phase differences from the 1 st antenna 10 with respect to the 2 nd antenna 12 (γ=60°), θ 32 from the 3 rd antenna 14 with respect to the 2 nd antenna 12 (γ=0) and θ 13 from the 1 st antenna 10 with respect to the 3 rd antenna 14 (γ=120°): x=− √{square root over (3)} y+ 2 R sin(θ 12 ) x=R sin(θ 32 ) x= √{square root over (3)} y+ 2 R sin(θ 13 ). Three equations (as represented by the three location lines) are therefore available to solve only two unknowns (x and y), resulting in an overdetermined system. Under ideal conditions, the three lines cross in a single point. In practice, factors such as interference, multipath or noise can cause the system to become inconsistent and the lines then define a triangular area 22 , called a cocked hat, within which the target is assumed to be located. After solving for the three corners of the cocked hat, various possibilities must be evaluated. For instance, two of the lines may be correctly resolved, in which case one of the corners of the cocked hat is the best estimate of the position. The history of previous measurements (i.e. an established track) may be used to identify such a solution. If no other information is available to identify the best solution, the centroid of the triangle may be used as the best estimate of target position. The centroid lies at x c = 2 ⁢ ⁢ sin ⁡ ( θ 32 ) + sin ⁡ ( θ 12 ) - sin ⁡ ( θ 13 ) 3 ⁢ R y c = sin ⁡ ( θ 13 ) + sin ⁡ ( θ 12 ) 3 ⁢ ⁢ R . The solution for the centroid in terms of the variables u ij =sin(θ ij ) is given by x c = 2 ⁢ u 32 + u 12 - u 13 3 ⁢ R y c = u 13 + u 12 3 ⁢ R . With the (x, y) coordinates of the target determined, the z-coordinate is found from the relationship between the coordinate positions and the range, R 2 =x 2 +y 2 +z 2 , as z c =√{square root over ( R 2 −x c 2 −y c 2 )} The size of the cocked hat is a useful indicator of the reliability of the measurement and serves as the 3D angle input to the confidence parameter, described in the next section. The side of the cocked hat normalized to unity range is given by s = 2 3 ⁢  u 13 + u 32 - u 12  . The proportionality constant is not of importance, so that the parameter Rel_size=| u 13 +u 32 −u 12 | is used as an indicator of the size of the cocked hat. The Confidence Parameter The quantity u for a specific antenna axis is calculated from the phase difference for each frequency (e.g. Δφ 12a and Δφ 12b ), using the estimates for p a and p b . u a = Δ ⁢ ⁢ ϕ m ⁢ ⁢ 12 ⁢ a 2 ⁢ π ⁢ ⁢ k a + p a k a u b = Δ ⁢ ⁢ ϕ m ⁢ ⁢ 12 ⁢ b 2 ⁢ π ⁢ ⁢ k b + p b k b Small errors ε 12a and ε 12b in the phase difference measurements Δφ m12a and Δφ m12b will cause errors ɛ 12 ⁢ a 2 ⁢ π ⁢ ⁢ k a ⁢ ⁢ and ⁢ ⁢ ɛ 12 ⁢ b 2 ⁢ π ⁢ ⁢ k b ⁢ in the calculated values for u. The resultant error in u with typical values for k a and k b is generally within the accuracy limits of the system. A phase difference error large enough to cause the integers (p a or p b ) to be incorrectly resolved will, however, result in a discrete and significant error in the calculated value of u. This allows for binary indicators to be set up for monitoring the reliability of the angle extraction. The confidence calculation is based on four inputs: three axis angle inputs (differences in calculated values of u) as well as a 3D angle input given by the relative size of the cocked hat. Four binary indicator outputs can then be calculated: the three axis angle confidence indicators and the 3D angle confidence indicator. These four outputs can then be suitably combined to arrive at a single confidence parameter. Three Axis Angle Confidence Indicators The large, discrete difference between u a and u b can be used as a binary indication of whether an integer p a or p b has been estimated incorrectly. This indicator is available for each of the three antenna axes. It may occasionally happen that the phase difference errors on the two frequencies are such that u a and u b remain in agreement, e.g. when both p a and p b are estimated incorrectly, in which case an error will not be indicated. Single 3D Angle Confidence Indicator An incorrect estimation of p a or p b that causes u to be incorrectly calculated on an axis will shift the location line associated with that axes. This will increase the size of the cocked hat by a discrete amount, which can again be used as a binary indication of a suspect angle extraction. Usage The confidence indicators are used as inputs to the tracking algorithm and are also made available to the user of the system. Example of a System Embodiment The Transceiver Three block diagrams showing the implementation of an FMCW radar transceiver of a rapid location 3D radar system according to an example embodiment of the present invention are shown in FIGS. 6 , 7 and 8 . The principle of ambiguity resolution is equally applicable to a coherent pulsed radar system implementation. FIG. 6 shows a multiplexed system with low hardware count, where the waveform generator generates alternating bursts at the frequencies f 1 and f 2 . FIG. 7 shows an implementation with a six channel receiver and a shared receive antenna array, where the bursts at frequencies f 1 and f 2 are transmitted simultaneously. FIG. 8 shows an implementation with a six channel receiver fed by six receive antennas where the bursts at frequencies f 1 and f 2 are transmitted simultaneously. The implementations in FIGS. 7 and 8 are the preferred implementations if rapid detection of the target is a high priority. The less expensive implementation in FIG. 6 is suitable for applications where the rapid detection of a target is not such a high priority. The implementation in FIG. 8 has the advantage that the receive antennas may be separately optimised for each frequency, and that the losses associated with the diplexers are eliminated. The principle of operation of the three systems is the same. With reference to FIG. 7 , a waveform generator 24 generates two chirped up sweep FMCW signals simultaneously, starting at 9.1 and 10.1 GHz respectively, each with a sweep rate of 3.125 THz/s and a sweep repetition frequency of 49.135 kHz. The effective sweep bandwidth is 51.2 MHz and the range resolution of the radar is 2.93 m. The signals are amplified to a level of 1 W by means of power amplifiers 26 and 28 . Two directional couplers 30 and 32 tap off local oscillator signals for the IQ down-converters in the receiver channels. The signals from the two power amplifiers are combined in a diplexer 34 and fed to the transmit antenna 36 , which is a 17 dB gain pyramidal horn with a horizontal and vertical 3 dB beamwidths of 25°. The echoes from the target are picked up by a receive array which consists of three horn antennas 38 , 40 and 42 which are identical to the transmit antenna 36 , arranged on the corners of an equilateral triangle with a horizontal base, and with an inter-antenna spacing of 192 mm, or 6.5λ at 10.1 GHz. The array can be tilted with its plane out of the vertical. The signals from the antennas are fed through PIN diode limiters 44 to the receivers where the two channels are separated with a diplexer filter 46 . The signal at f 1 is fed to a low noise amplifier 48 and IQ down-converter 52 . The LO signal for the down-converter is a sample of the transmit signal for that channel, so that the intermediate frequency output signal from the down-converter is around zero frequency and known as a zero-frequency IF (ZIF). The IF signal is amplified by a low noise amplifier 56 and passed through a polyphase filter 60 that selects the lower sideband. A sensitivity-frequency control (SFC) and amplifier-filter circuit 64 , that shapes the frequency response of the receive channel so as to reduce the sensitivity of the radar for close-by targets which produce low-frequency responses, amplifies the signal and low-pass filters it to band-limit the signal to less than 7.8 MHz. Finally, the band-limited is passed through an analogue to digital converter (ADC) 68 and the resulting digital signal is fed to the signal processor (see FIG. 9 ). The f 2 signal from the diplexer is fed through an identical receiver channel 50 , 54 , 58 , 62 , 66 and 70 but fed with an LO signal at f 2 . A further two identical pairs of receiver channels down-convert the signals from the antennas 40 and 42 to produce six IF output signals in total. The Signal Processor A functional block diagram of the signal processor is shown in FIG. 9 . The six IF signals from the three receiver channels are fed in at the top of the block diagram, to respective ADCs 72 . 1 , 72 . 2 , 72 . 3 and 74 . 1 , 74 . 2 , 74 . 3 where they are sampled. (The same ADCs are also shown in FIGS. 7 and 8 ). The respective samples are fed to an FFT process 76 . 1 , 76 . 2 , 76 . 3 and 78 . 1 , 78 . 2 , 78 . 3 to produce the 256 sample range FFT. The positive 128 bins of the range FFTs are fed to a second FFT process 80 . 1 , 80 . 2 , 80 . 3 and 82 . 1 , 82 . 2 , 82 . 3 to produce Doppler spectra for each of the 128 range bins and for each of the six channels. The output of these processes are a set of range-Doppler maps of complex numbers, of which the phase and magnitude values are calculated at 84 . 1 , 84 . 2 , 84 . 3 and 86 . 1 , 86 . 2 and 86 . 3 . Detections are registered separately for each of the two frequencies by summing the magnitudes of the three range-Doppler maps for each antenna at each frequency, at 88 and 90 , and taking the logarithm of the result at 92 and 94 . This signal is then passed through a slow and a fast integrator 96 , 98 and 100 , 102 after which the slow signal is subtracted from the fast signal using a comparator 104 and 106 and passed to a threshold detector 108 and 110 , and a binary integrator 112 , to make an m out of n detection decision. A specific target will produce different Doppler spectra at the two frequencies. The relationship between the Doppler spectra at the two frequencies is known and is consequently used to resolve velocity ambiguities and to distinguish between inbound and outbound targets. The information is then passed to a track manager 114 which rejects sporadic detections and establishes tracks on detections with compatible velocity and range sequences. Once a track is established, the phase differences between signals from the different antennas for that target are extracted at 116 from the range-Doppler maps for frequencies f 1 and f 2 , and passed through smoothing filters to the ambiguity resolver which identifies the correct angle of arrival. Finally, azimuth and elevation angles, range, velocity, time-stamp, signal to clutter ratio and confidence parameter output is produced for each tracked target. TYPICAL APPLICATIONS The radar system described here has many potential applications. A first application is as a short range radar that can accurately measure the trajectories of objects such as cricket balls, projectiles, missiles and rockets, as shown in FIG. 10 . The radar is located in a compact housing 118 which contains the antennas 36 , 38 , 40 and 42 and the associated electronics. The radar can conveniently be supported on a tripod 120 or other portable support structure, or could be mounted to a pole or other fixed structure. Since the direction in which a cricket ball is going to be hit is unknown, the search volume can be set to include the full volume above a cricket field where a ball is likely to travel. The radar can locate the cricket ball within a few milliseconds after being hit. The radar location can then be used to direct a video camera at the ball for live TV coverage of the event, and also accurately report the speed with which the ball is travelling and also predict the point where the ball will hit the ground. A similar application would be to track projectiles at a test firing range or to track and determine the origin of small arms fire during peace-keeping operations. With its ability to accurately determine the location of objects in space, a radar according to this invention is also excellently suited as a radar sensor to enable precision guidance of manned and unmanned aerial vehicles during take-off and landing. Another application is as a “gap-filler” radar, e.g. in a wind-farm, as shown in FIG. 11 . Wind-farms present a hazard to air traffic control, as standard ATC radars cannot detect aircraft overflying wind farms reliably because of the limited observation time each time the antenna scans across the wind farm. The gap-filler radar, on the other hand, observes the turbine blades continuously and can distinguish between aircraft targets and turbine blades. In FIG. 11 , a wind farm 122 has several wind turbines 124 . A gap filler radar 126 according to the invention is located centrally in the wind farm, facing upwardly. The cylindrical coverage diagram of the radar is indicated by the numeral 128 . The gap filler radar detects and reports aircraft overflying the wind farm to the ATC radar which is adversely affected by the wind-farm. With its ability to rapidly detect and locate an incoming target, a radar according to the invention is excellently suited as a radar sensor for an armoured vehicle protection system, as shown in FIG. 12 . The radar sensor unit 130 is mounted on the side of an armoured vehicle 132 . On detection of an incoming projectile 134 , such as a rocket propelled grenade, the location and trajectory of the projectile is sent to a countermeasures system 136 which directs a counter-projectile at the incoming grenade to destroy it before it reaches the armoured vehicle. In summary, the above described floodlight radar system is able rapidly to detect and locate multiple fast moving targets in three dimensions. The radar continuously surveys a quarter hemisphere of space, and 3D target position is determined by a sparse interferometer array consisting of only three receive antennas arranged in two dimensions. Once a track is established, target angular ambiguities associated with sparse direction finding arrays are resolved by employing a frequency diversity waveform scheme. The radar generates a confidence parameter which flags unreliable measurements when multipath propagation or noise degrades the accuracy of a measurement.

A floodlight radar system includes a transmitter arranged to generate output waveforms at first and second centre frequencies, and at least one transmit antenna configured to illuminate a search volume constantly at the first and second centre frequencies. A sparse array of receive antennas is arranged in a common plane and configured to monitor the search volume constantly. The system includes a receive circuit arranged to extract target position information from return signals received by each antenna, and a signal processor circuit which is arranged to resolve ambiguity in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences at the first and second frequencies, to calculate azimuth, elevation, range and velocity of a target identified in the search volume. The system is able to rapidly detect and locate multiple fast moving targets in three dimensions.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority to U.S. Provisional Application No. 60/261,654, filed Jan. 13, 2001, the disclosure of which is incorporated herein by reference in its entirety. STATEMENT OF GOVERNMENT SUPPORT [0002] This invention was made with government support under grant number K08 AI01728-01 and U0I-A133383 from the National Institutes of Health. The United States government may have certain rights in this invention. FIELD OF THE INVENTION [0003] This invention relates to the treatment of bovine viral diarrhea virus (BVDV) and hepatitis C virus (HCV) infections. BACKGROUND OF THE INVENTION [0004] Bovine viral diarrhea virus (BVDV) is an enveloped, single-stranded, positive sense RNA virus in the genus Pestivirus and the family Flaviviridae. Based on the presence or absence of visible cytopathic effect when susceptible cell monolayers are infected, two pathogenic biotypes of BVDV, referred to as cytopathic and noncytopathic, have been identified. Perdrizet J A in: B. P. Smith (ed), Large Animal Internal Medicine, First Edition (Mosby Press, St Louis, 731-737 (1990)). A differentiation is also made between biotypes of BVDV (referred to as biotypes I and II) based on certain viral RNA sequences in the 5′ untranslated region of the genome. Pellerin C, et al., Virology 203, 260-268 (1994); J. F. Ridpath et al., Virology 205, 66-74 (1994). [0005] BVDV may cause acute infection in cattle, resulting in bovine respiratory disease, diarrhea and severe reproductive losses. Clinical symptoms of acute BVDV infection may range from the almost undetectable to the severe. Infection of pregnant cows and heifers may result in breeding problems (e.g., irregular heats), abortion, premature births or the birth of weak or stunted calves. In some cases, temporary damage to an animal's immune system may occur even when the clinical symptoms are not apparent. In addition to the illness caused by the virus itself, infected animals are more susceptible and are more likely to suffer from other diseases, such as pneumonia. [0006] In addition to causing acute disease, BVDV may also establish persistent infections. Potgieter, Vet. Clin. North Am. Food Anim. Pract 11, 501-520 (1995). Persistent BVDV infections are generally established via in utero infection of a developing fetus with a noncytopathic BVDV. The resulting animals are born immunotolerant of the particular BVDV by which they are infected, and may continually shed virus throughout their life span. While some persistently infected animals exhibit congenital malformations due to BVDV infection, many animals persistently infected with BVDV appear clinically normal. Baker, Rev. Sci. Tech 9, 25-41 (1990); Bielefeldt-Ohmann, Vet. Clin. North Am. Food Anim. Pract 11, 447-476 (1995). Persistently infected animals are thought to be the major disseminators of BVDV in the cattle population. [0007] There are more than 140 vaccines against BVDV commercially available in the United States. Bolin, Am J. Vet Res. 46, 2476-2470 (1995). Unfortunately, vaccination does not provide complete protection against BVDV infection, as some vaccinated cattle still become infected with the virus. At present, there is no known cure for BVDV infection. Accordingly, a need exists for an effective treatment for BVDV infection. [0008] In vitro production of embryos has become a useful therapy for increasing reproductive performance of animals and for treating infertility of both animals and humans. In vitro production of bovine embryos could permit the humane, world-wide transfer of genetic material among cattle while limiting the transmission of many pathogens. However, in vitro-produced bovine embryos are potential vectors for transmission of BVDV. B. Avery et al., Vet Rec 132, 660 (1993); A. Bielanski et al., Theriogenology 46, 1467-1476 (1996); T. Tsuboi et al., Vet Microbiol 49, 127-134 (1996); O. Zurovac et al., Theriogenology 41, 841-853 (1994). BVDV can be introduced into the embryo production system in association with gametes, serum, somatic cells, cumulus oocyte complexes (COCs), and result in contaminated in vitro fertilized (IVF) embryos or cell lines. K. V. Brock et al., J Vet Diagn Invest 3, 99-100 (1991); C. R. Rossi et al., Am J Vet Res 41, 1680-1681 (1980); P. J. Booth et al., J Reprod Fert Abstr Ser Suppl 9, 28 (1992); M. D. Fray et al., Vet Pathol 35, 253-259 (1998); R. Harasawa et al., Microbiol Immunol 39, 979-985 (1995); T. Shin et al., Theriogenology 53, 243 (2000). Association of noncytopathic BVDV with transferred IVF embryos may cause infection of embryo recipients, early embryonic death, abortion or birth of persistently infected offspring. [0009] An analogous hazard exists in human in vitro embryo production. Viral transmission to human embryos and embryo recipients by means of contaminated embryo culture media has been reported. Addition of an anti-viral agent to the culture medium surrounding in vitro-produced embryos could prevent or reduce transmission of virus to the embryo or embryo recipient. P. M. Grosheide et al., Vaccine 9, 682-687 (1991); W. G. Quint et al., J Clin Microbiol 32, 1099-1100 (1994); H. C. van Os et al., Am J Obstet Gynecol 165, 152-159 (1991). Accordingly, an antiviral agent that could be added to both animal and human in vitro embryo production systems may have important applications. [0010] The organization of the portion of the BVDV genome that encodes the proteins used in viral replication is very similar to that of human hepatitis C virus (HCV), another flavivirus. S. W. Behrens et al., J Virol 72, 2364-2372 (1998). It is believed that more than 80% of the individuals infected with HCV will eventually develop a chronic form of the disease. As the disease develops, the liver of the infected subject is progressively damaged, with the symptoms generally being commensurate with cirrhosis and liver failure (e.g. jaundice, abdominal swelling, and finally, coma). The cycle of disease from infection to significant liver damage can take 20 years or more. Liver failure due to HCV is the presently the leading cause of liver transplants in the United States. It is suspected that there are, at present, more than 5 million people in the United States that are infected with HCV, and perhaps as many as 200 million around the world, making HCV infection a significant public health threat. [0011] The development of a vaccine for HCV infection is uncertain, due in part to the high mutation rate of the virus. Recombinant interferon alpha-2b (INTRON A®/Schering) has proved effective in some cases of chronic hepatitis C. However, it has been reported that relapse occurs in at least half the responders after the interferon alpha-2b treatment is discontinued. Additionally, interferon alpha-2b may exacerbate hepatocyte injury caused by autoimmune chronic active hepatitis. J. Y. N. Lau et al., Br Med J. 306, 469-470 (1993). The nucleotide analog ribavirin (VIRAZOLE®/ICN Pharmaceuticals) has been shown to reduce concentrations of hepatitis C viral RNA in an infected subject, although at a slower rate than interferon alpha-2b. As with BVDV infection, a need exists for an effective treatment for HCV infection. SUMMARY OF THE INVENTION [0012] In view of the foregoing, one aspect of the invention relates to novel compounds that are useful in treating members of the Flaviviridae family of viruses, such as bovine viral diarrhea virus (BVDV) infection and hepatitis C virus (HCV) infection. Compounds of the present invention will have a structure according to Formulas (I)-(VI), as follows: [0013] wherein: [0014] X 1 and X 3 are each independently selected from the group consisting of O, S and NR 9 , wherein R 9 is H or alkyl; [0015] X 2 and X 4 are each independently CH or N; [0016] A is selected from the group consisting of H, alkyl, aryl, [0017] R 1 , R 2 , R 3 , R 4 and R 5 are each independently selected from the group consisting of H, alkyl, alkoxy, amidine, halide, alkylhalide, nitro and amino groups; [0018] R 6 is H, alkyl or aryl; and [0019] R 7 and R 8 are each independently selected from the group consisting of H and alkyl. [0020] Additional aspects of the invention include pharmaceutical compositions comprising a compound having a structure according to Formulas (I)-(VI), or a pharmaceutical salt thereof (i.e., an “active compound”), in a pharmaceutically acceptable carrier. Pharmaceutical compositions of the present invention are useful in the treatment of bovine viral disease virus (BVDV) infection and hepatitis C virus (HCV) infection. [0021] Certain aspects of the invention relate to methods of treating bovine viral disease virus (BVDV) infection in a subject in need of such treatment. The method comprises administering to the subject a compound according to Formulas (I) through (VI), or a pharmaceutically acceptable salt thereof, in an amount effective to treat bovine viral disease virus (BVDV) infection. [0022] Other aspects of the invention relate to methods of treating hepatitis C virus (HCV) infection in a subject in need of such treatment. The method comprises administering to the subject a compound according to Formulas (I) through (VI), or a pharmaceutically acceptable salt thereof, in an amount effective to treat hepatitis C virus (HCV) infection. [0023] A further aspect of the present invention is the use of the active compounds described herein for the manufacture of a medicament for the treatment of bovine viral disease virus (BVDV) infection in a subject in need of such treatment. [0024] Still another aspect of the present invention is the use of the active compounds described herein for the manufacture of a medicament for the treatment of treating hepatitis C virus (HCV) infection in a subject in need of such treatment. [0025] The foregoing and other aspects of the present invention are explained in detail in the specification set forth below. BRIEF DESCRIPTION OF THE DRAWINGS [0026] FIG. 1 illustrates four chemical schemes useful in the synthesis of compounds of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0027] The present invention now will be described more fully hereinafter with reference to the accompanying specification and drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. [0028] The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a”, “an” and “the” 0 are intended to include the plural forms as well, unless the context clearly indicates otherwise. [0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. [0030] With respect to the compounds of the Formulas (I) through (VI), as used herein, the term “alkyl” refers to C1-10 inclusive, linear, branched, or cyclic, saturated or unsaturated (i.e., alkenyl and alkynyl) hydrocarbon chains, including for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, octenyl, butadienyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, and allenyl groups. The term “alkyl” specifically includes cycloakyl hydrocarbon chains, which as used herein refers to C3 to C6 cyclic alkyl, such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. In the present invention preferred alkyls are the lower alkyls. The term “lower alkyl” refers to C1 to C4 linear or branched alkyl, such as methyl, ethyl, propyl, butyl, isopropyl, sec-butyl, and tert-butyl. [0031] The term “alkyl” also encompasses substituted alkyls, which include aminoalkyls, hydroalkyls, oxygen-substituted alkyls (i.e., alkoxy groups), and halogen-substituted alkyls (i.e., alkyl halides, polyhaloalkyls). The term “aminoalkyl,” as used herein, refers to C1 to C4 linear or branched amino-substituted alkyl, wherein the term “amino” refers to the group NR′R″, arid wherein R′ and R″ are independently selected from H or lower alkyl as defined above, i.e., —NH 2 , —NHCH 3 , —N(CH 3 )2, etc. The term “hydroxyalkyl” as used herein refers to C1 to C4 linear or branched hydroxy-substituted alkyl, i.e., —CH 2 OH, —(CH 2 ) 2 OH, etc. The term “alkoxy” as used herein refers to C1 to C4 oxygen-substituted alkyl, i.e., —OCH 3 . The term “loweralkoxy,” as used herein, refers to C1 to C4 linear or branched alkoxy, such as methoxy, ethoxy, propyloxy, butyloxy, isopropyloxy, and t-butyloxy. [0032] The terms “halo” and “halide” have their conventional meaning and refer to fluoro, chloro, bromo, and iodo groups. Preferred halo groups include chloro groups, and preferred alkyl halides of the present invention include CF 3 . “Nitro” groups, as used herein, have the structure —NO 2 . [0033] The term “aryl” as used herein refers to C3 to C10 cyclic aromatic groups such as phenyl, naphthyl, and the like, and specifically includes substituted aryl groups including but not limited to tolyl, substituted phenyl, and substituted naphthyl. Aryl groups may be substituted with halo, amino, nitro, and the like. Heterocyclic aromatic rings and polycyclic aromatic groups are also included in this definition of “aryl.” Specific examples of aryl groups encompassed by the present invention include but are not limited to cyclopentadienyl, phenyl, furan, thiophene, pyrrole, pyran, pyridine, imidazole, isothiazole, isoxazole, pyrazole, pyrazine, pyrimidine, and the like. [0034] The compounds of the present invention are also useful in the form of their pharmaceutically acceptable salt forms. Such salts may include, but are not limited to, the gluconate, lactate, acetate, tartarate, citrate, phosphate, borate, nitrate, sulfate, hydrobromide and hydrochloric salts of the compounds. Compounds of Formulas (I)-(VI) and their pharmaceutically acceptable salts are referred to herein as “active compounds” or “active agents.” [0035] The compounds represented by the Formulas (I) through (VI) may be formed by synthesis procedures that are described in the Examples below, as well as by certain methods known in the art. Some of these known methods are set forth below in the Examples by description or by reference (the disclosures of which are all incorporated herein by reference in their entirety). [0036] Examples of compounds useful in the present invention are set forth in Table 1, below. In Table 1, the A groups are as follows: TABLE 1 Selected Compounds Of The Present Invention Compound Name Formula A X1 X2 X3 X4 R1 R2 R3 R4 R6 R7 R8 DB 456 I A3 O C NH N NH2 H H H — H H DB 457 I A3 O C NH N NO2 H H H — H H DB 458 I A1 O C NH N NO2 H H H alkyl — — DB 459 I A1 O C NH N NH2 H H H alkyl — — DB 606 V A3 O C — — OCH3 H H H H H H DB 619 VI A1 NH C — — H H H — H — — DB 673 VI A2 O C — — H H H — H — — DB 680 VI A2 O C — — CH 3 H CH 3 — H — — DB 686 VI A2 S C — — H H H — H — — DB 687 VI A2 S N — — H H H — H — — DB 700 VI A2 O C — — H H H — H — — DB 701 VI A2 O C — — CF3 H CF3 — H — — DB 705 VI A2 O C — — H H H — H — — DB 708 VI A2 O C — — Cl H Cl — H — — DB 711 VI A2 O C — — OCH 3 H OCH 3 — H — — DB 752 VI A2 S C — — CH 3 H CH 3 — H — — DB 771 II A2 O C NH N H H H — H — — DB 772 II A3 O C NH N H H H — — H H [0037] Formulas of the compounds set forth above are as follows: [0038] As noted above, the compounds, methods and compositions of the present invention are useful for treating bovine viral diarrhea virus (BVDV) infections and hepatitis C virus (HCV) infections. The term bovine viral diarrhea virus infection means any infection (e.g., acute, latent or persistent) caused by a virus classified as a bovine viral disease virus (BVDV). As set forth above, BVDV is an enveloped, single-stranded, positive sense RNA virus in the genus Pestivirus and the family Flaviviridae. The term bovine viral disease virus (BVDV), as used herein, encompasses all BVDV strains and all serotypes and variants thereof, including live, attenuated, killed or otherwise inactivated forms. The term BVDV specifically includes cytopathic and noncytopathic strains, and strains of both biotype I and biotype II. The term “hepatitis C virus (HCV) infection” includes any infections caused by the hepatitis C virus (HCV), which includes all strains, serotypes and variants of HCV. [0039] In one embodiment of the invention, a subject is administered a therapeutically-effective amount of the compound of formulas (I) through (VI), or a pharmaceutically acceptable salt thereof. A “therapeutically-effective” amount as used herein is an amount of a compound of formulas (I) through (VI) that is sufficient to alleviate (e.g., mitigate, decrease, reduce) at least one of the symptoms associated with BVDV or HCV infection. It is not necessary that the administration of the compound eliminate the symptoms of BVDV or HCV, as long as the benefits of administration of compound outweigh the detriments. Likewise, the terms “treat” and “treating” in reference to BVDV or HCV, as used herein, are not intended to mean that the avian subject is necessarily cured of BVDV or HCV, or that all clinical signs thereof are eliminated, only that some alleviation or improvement in the condition of the subject is effected by administration of the compound of Formulas (I) through (VI). [0040] Suitable subjects of the present invention include humans and animals. When the subject is an animal, mammals are preferred, with livestock (e.g., cattle, pigs, sheep, horses) and primates (e.g., monkeys, apes) being particularly preferred. In embodiments of the present invention where BVD are treated, bovine subjects (e.g., cows, bulls, calves) are preferred. In embodiments of the present invention where HCV infections are treated, humans are the preferred subjects. Subjects may be adult, adolescent, juvenile, infant, or neonatal. In one embodiment of the invention, the subject is a live embryo, and may be in utero or in vitro (in the case of an embryo being maintained for in vitro fertilization). [0041] Subjects may be administered the compounds and compositions of the present invention by any suitable means. Exemplary means are oral administration (e.g., in the form of a liquid or solid), intramuscular injection, subcutaneous injection, and intravenous injection. Pharmaceutical formulations of the present invention comprise active compounds of the invention in a pharmaceutically acceptable carrier. Suitable pharmaceutical formulations include those suitable for inhalation, oral, rectal, topical, (including buccal, sublingual, dermal, vaginal and intraocular), parenteral (including subcutaneous, intradermal, intramuscular, intravenous and intraarticular) and transdermal administration. The most suitable route of administration in any given case may depend upon the anatomic location of the condition being treated in the subject, the nature and severity of the condition being treated, and the particular active compound which is being used. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art. [0042] In methods of the present invention where treatment is carried out during an in vitro fertilization (IVF) procedure, the compounds may be administered to the embryo by adding the active compound, in a suitable concentration, to the medium in which the embryo is being obtained. [0043] In the manufacture of a medicament according to the invention (the “formulation”), active compounds or the pharmaceutically acceptable salts thereof (the “active compounds”) are typically admixed with, inter alia, an acceptable carrier. The carrier must, of course, be acceptable in the sense of being compatible with any other ingredients in the formulation and must not be deleterious to the patient. The carrier may be a solid or a liquid, or both, and is preferably formulated with the compound as a unit-dose formulation, for example, a tablet, which may contain from 0.5% to 99% by weight of the active compound. One or more active compounds may be incorporated in the formulations of the invention, which formulations may be prepared by any of the well known techniques of pharmacy consisting essentially of admixing the components, optionally including one or more accessory therapeutic ingredients. [0044] Formulations suitable for oral administration may be presented in discrete units, such as capsules, cachets, lozenges, or tablets, each containing a predetermined amount of the active compound; as a powder or granules; as a solution or a suspension in an aqueous or non-aqueous liquid; or as an oil-in-water or water-in-oil emulsion. Such formulations may be prepared by any suitable method of pharmacy which includes the step of bringing into association the active compound and a suitable carrier (which may contain one or more accessory ingredients as noted above). In general, the formulations of the invention are prepared by uniformly and intimately admixing the active compound with a liquid or finely divided solid carrier, or both, and then, if necessary, shaping the resulting mixture. For example, a tablet may be prepared by compressing or molding a powder or granules containing the active compound, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the compound in a free-flowing form, such as a powder or granules optionally mixed with a binder, lubricant, inert diluent, and/or surface active/dispersing agent(s). Molded tablets may be made by molding, in a suitable machine, the powdered compound moistened with an inert liquid binder. Formulations for oral administration may optionally include enteric coatings known in the art to prevent degradation of the formulation in the stomach and provide release of the drug in the small intestine. [0045] Formulations of the present invention suitable for parenteral administration comprise sterile aqueous and non-aqueous injection solutions of the active compound, which preparations are preferably isotonic with the blood of the intended recipient. These preparations may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient. Aqueous and non-aqueous sterile suspensions may include suspending agents and thickening agents. The formulations may be presented in unit\dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, saline or water-for-injection immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described. For example, in one aspect of the present invention, there is provided an injectable, stable, sterile composition comprising a compound of Formula (I)-Formula (VI), or a salt thereof, in a unit dosage form in a sealed container. The compound or salt is provided in the form of a lyophilizate which is capable of being reconstituted with a suitable pharmaceutically acceptable carrier to form a liquid composition suitable for injection thereof into a subject. The unit dosage form typically comprises from about 10 mg to about 10 grams of the compound or salt. When the compound or salt is substantially water-insoluble, a sufficient amount of emulsifying agent which is physiologically acceptable may be employed in sufficient quantity to emulsify the compound or salt in an aqueous carrier. [0046] Further, the present invention provides liposomal formulations of the compounds disclosed herein and salts thereof. The technology for forming liposomal suspensions is well known in the art. When the compound or salt thereof is an aqueous-soluble salt, using conventional liposome technology, the same may be incorporated into lipid vesicles. In such an instance, due to the water solubility of the compound or salt, the compound or salt will be substantially entrained within the hydrophilic center or core of the liposomes. The lipid layer employed may be of any conventional composition and may either contain cholesterol or may be cholesterol-free. When the compound or salt of interest is water-insoluble, again employing conventional liposome formation technology, the salt may be substantially entrained within the hydrophobic lipid bilayer which forms the structure of the liposome. In either instance, the liposomes which are produced may be reduced in size, as through the use of standard sonication and homogenization techniques. [0047] Of course, the liposomal formulations containing the pharmaceutically active compounds identified with the methods described herein may be lyophilized to produce a lyophilizate which may be reconstituted with a pharmaceutically acceptable carrier, such as water, to regenerate a liposomal suspension. [0048] In addition to the active compounds, the pharmaceutical formulations may contain other additives, such as pH-adjusting additives. In particular, useful pH-adjusting agents include acids, such as hydrochloric acid, bases or buffers, such as sodium lactate, sodium acetate, sodium phosphate, sodium citrate, sodium borate, or sodium gluconate. Further, the compositions may contain microbial preservatives. Useful microbial preservatives include methylparaben, propylparaben, and benzyl alcohol. The microbial preservative is typically employed when the formulation is placed in a vial designed for multidose use. Of course, as indicated, the pharmaceutical formulations of the present invention may be lyophilized using techniques well known in the art. [0049] Pharmaceutical formulations of the present invention may comprise compounds of the present invention in lyophilized form. Alternatively, pharmaceutical formulations of the present invention may comprise compounds of the present invention in a pharmaceutically acceptable carrier. Such pharmaceutical formulations are generally made by admixing the compounds described herein with a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are preferably liquid, particularly aqueous, carriers, the selection of which are known in the art. For the purpose of preparing such formulations, the compound may be mixed in a buffered saline (e.g., pH 6 to 8) or conventional culture media. The formulation may be stored in a sterile glass container sealed with a rubber stopper through which liquids may be injected and formulation withdrawn by syringe. [0050] With respect to all the methods described herein, a therapeutically effective dosage of any specific compound, the use of which is in the scope of present invention, may vary somewhat from compound to compound and subject to subject, and will depend upon the condition of the subject and the route of delivery. A dosage from about 1 mg/kg to about 15 mg/kg of subject body weight, or about 20 mg/kg of subject body weight, or even about 25 mg/kg of subject body weight may be employed for intravenous injection or oral administration. [0051] The concentration of the compound of the present invention or a pharmaceutically acceptable salt thereof in a formulation of the present invention may be determined by the skilled artisan and will vary according to certain conditions, including the characteristics of subject being treated (e.g., species, age, weight), the severity and type of the infecting virus or the strain that the subject is being vaccinated against, the dosage form being used, and the like. [0052] The compounds of the present invention may be administered in conjunction with other antiviral compounds, as may be determined by the skilled artisan. [0053] The present invention is explained in greater detail in the Examples which follow. These examples are intended as illustrative of the invention, and are not to be taken as limiting thereof. EXAMPLES 1-12 Synthesis of Inventive Compounds [0054] In the following Examples, compound numbers (compounds 2, 5, 5a, etc.) refer to compounds with structures that are set forth in FIG. 1 . EXAMPLE 1 [0055] General Methodology: Chemical Synthesis and Analysis [0056] Melting points were determined with a MEL-TEMP® 3.0 capillary melting point apparatus and are uncorrected. 1 H nuclear magnetic resonance spectra were recorded on a Varian Unity+300 or a Varian VRX 400 instrument, with peak assignments relative to residual DMSO (2.49 ppm) or CHCl 3 (7.24 ppm). Mass spectra were recorded on a VG Instruments 70-SE spectrometer at the Georgia Institute of Technology, Atlanta, Ga. Elemental analyses were performed by Atlantic Microlab, Norcross, Ga. All final compounds were dried in vacuo (oil pump) at 50-60° C. for at least 36 hours before elemental analysis. Unless otherwise stated, all reagent chemicals and solvents (including anhydrous solvents) were purchased from Aldrich Chemical Co., Fisher Scientific, or Lancaster Synthesis and used as received. Acetonitrile (CaH 2 ), triethylamine (CaH 2 ), and ethanol (Mg/I 2 ) were distilled from the indicated drying agent. 2,6-Dimethyl-4-nitrobromobenzene and S-(2-Naphthylmethyl)thioacetimidate were prepared according to the literature. See B. M. Wepster, Rec. Trav. Chim. 73, 809-818 (1954); D. N. Kravtsov, J. Organometal. Chem. 36, 227-237 (1972); B. G. Shearer et al., Tetrahedron Lett. 38, 179-182 (1997). EXAMPLE 2 Preparation of 2,5-bis(4-nitrophenyl)furans [0057] The following representative procedures are variations of a general procedure previously described in A. Kumar et al., Heterocyclic Comm. 5, 301-304 (1999). [0058] 2,5-Bis(2-methyl-4-nitrophenyl)furan (Compound 2b). To a solution of 2-bromo-5-nitrotoluene (4.32 g, 20 mmol) and tetrakis(triphenylphospine)palladium (0) (0.40 g) in anhydrous 1,4-dioxane (50 ml) was added 2,5-bis(tri-n-butylstannyl)furan (6.46 g, 10 mmol) and the mixture was heated overnight under nitrogen at 95-100° C. The resulting orange suspension was diluted with hexanes (15 ml), cooled to room-temperature, and filtered to give, after rinsing with hexanes, an orange solid (3.10 g), mp 241-243° C. The product was recrystallized from DMF (100 ml) to give a bright orange fluffy solid (2.87 g, 85%), mp 242-243° C. 1 H NMR (DMSO-d 6 ): 2.69 (s, 6H), 7.31 (s, 2H), 8.12 (m, 4H), 8.23 (s, 2H). Anal. Calcd. for C 18 H 14 N 2 O 5 (338.31): C, H, N. [0059] 2,5-Bis(4-nitrophenyl)furan (Compound 2a). Yield: 88%; orange fluffy solid; mp 269-270° C. (not recrystallized), lit. mp 270-272° C., Ling, C. et al., J. Am. Chem. Soc. 1994, 116, 8784-8792. [0060] 2,5-Bis(2-methoxy-4-nitrophenyl)furan (Compound 2c). Yield: 77%; bright orange granular solid; mp 308-310° C. (DMF). 1 H NMR (DMSO-d 6 ): 4.10 (s, 6H), 7.37 (s, 2H), 7.90 (s, 2H), 7.94 (d, 2H), 8.22 (d, 2H). Anal. Calcd. for C 18 H 14 N 2 O 7 .0.1H 2 O (372.11): C, H, N. [0061] 2,5-Bis(2-chloro-4-nitrophenyl)furan (Compound 2d). Yield: 71%; fluffy orange solid; mp 247-247.5° C. (DMF/MeOH). 1 H NMR (DMSO-d 6 ): 7.70 (s, 2H), 8.29 (dd, J=8.8, 2.2 Hz, 2H), 8.36 (d, J=8.8 Hz, 2H), 8.43 (d, J=2.2 Hz, 2H). Anal. Calcd. for C 16 H 8 Cl 2 N 2 O 5 (379.15): C, H, N. [0062] 2,5-Bis(4-nitro-2-trifluoromethylphenyl)furan (Compound 2e). Yield:. 74%; fluffy golden needles; mp 158.5-159° C. (EtOH). 1 H NMR (DMSO-d 6 ): 7.38 (s, 2H), 8.24 (d, J=8.7 Hz, 2H), 8.57 (d, J=2.4 Hz, 2H), 8.62 (dd, J=8.6, 2.4 Hz, 2H). Anal. Calcd. for C 18 H 8 F 6 N 2 O 5 (446.26): C, H, N. [0063] 2,5-Bis(2,6-dimethyl-4-nitrophenyl)furan (Compound 2f). Yield: 65%; yellow needles; mp 156.5-157.5° C. (DMF/EtOH/H 2 O). 1 H NMR (DMSO-d 6 ): 2.34 (s, 12H), 6.85 (s, 2H), 8.04 (s, 4H). Anal. Calcd. for C 20 H 18 N 2 O 5 (366.36): C, H, N. EXAMPLE 3 Preparation of 2,5-bis(4-aminophenyl)furans [0064] The following procedures are representative. [0065] 2,5-Bis(4-amino-2-methylphenyl)furan (Compound 3b). To a suspension of the bis-nitro derivative 2b (2.87 g) in EtOAc (90 ml) and dry EtOH (10 ml) was added Pd/C (10%) (0.40 g) and the mixture was hydrogenerated on a Parr apparatus at an initial pressure of ˜50 psi. After the uptake of hydrogen subsided (generally 3-6 hours), the resulting solution was filtered over Celite and the pale yellow to colorless filtrate was concentrated in vacuo to near dryness to give, after dilution with hexanes, the pure diamine as a pale yellow/green solid (2.17 g, 91%), mp 174-176° C., which required no purification. 1 H NMR (DMSO-d 6 ): 2.33 (s, 6H), 5.15 (br s, 4H), 6.42 (s, 2H), 6.46 (m, 4H), 7.35 (d, 2H). MS (EI): m/z 278 (M + ). [0066] 2,5-Bis(4-aminophenyl)furan (Compound 3a). Yield: 94%; pale green/tan solid; mp 218-221° C., lit 46 mp 213-216° C. MS (EI): m/z 250 (M + ). [0067] 2,5-Bis(4-amino-2-methoxyphenyl)furan (Compound 3c). The original oil was reconcentrated with benzene to give a yellow/tan solid which was triturated with ether. Yield: 79%; mp 201-202.5° C. 1 H NMR (DMSO-d 6 ): 3.80 (s, 6H), 5.25 (br s, 4H), 6.24 (dd, J=8.3, 2.0 Hz, 2H), 6.30 (d, J=1.9 Hz 2H), 6.56 (s, 2H), 7.48 (d, J=8.4 Hz, 2H). MS (EI): m/z 310 (M + ). [0068] 2,5-Bis(4-amino-2-trifluoromethylphenyl)furan (Compound 3e). Original red oil crystallized from EtOAc/hexanes in two crops as a red/orange solid. Combined yield: 81%; mp (first/major crop) 89.5-91° C.; mp (second crop) 91.5-92° C. 1 H NMR (DMSO-d 6 ): 5.79 (br s, 4H), 6.52 (s, 2H), 6.82 (dd, J=8.4, 2.4 Hz, 2H), 6.98 (d, J=2.2 Hz, 2H), 7.43 (d, J=8.4 Hz, 2H). MS (EI): m/z 386 (M + ). [0069] 2,5-Bis(4-amino-2,6-dimethylphenyl)furan (Compound 3f). Yield: 99%; white fluffy solid; mp 144.5-146° C. 1 H NMR (DMSO-d 6 ): 2.01 (s, 6H), 5.06 (br s, 4H), 6.24 (s, 2H), 6.29 (s, 4H). MS (EI): m/z 306 (M + ). [0070] 2,5-Bis(4-amino-2-chlorophenyl)furan (Compound 3d). To a suspension of the corresponding bis-nitro derivative 2d (1.22 g, 3.2 mmol) in dry EtOH (100 ml) and DMSO (20 ml) was added SnCl 2 .2H 2 O (5.80 g, 25.7 mmol) and the mixture was heated under nitrogen at 80° C. After 4-5 hours, TLC showed that starting material had been consumed, and thus the mixture was cooled, neutralized with NaOH (aq), and extracted with EtOAc. The extract was washed with water, brine, then dried (Na 2 SO 4 ) and concentrated. The resulting oil was crystallized from benzene/hexane with partial concentration to give a light brown solid (0.74 g, 71%), mp 191.5-193° C. Catalytic hydrogenation was not explored. 1 H NMR (DMSO-d 6 ): 5.60 (br s, 4H), 6.61 (dd, J=8.6, 2.2 Hz, 2H), 6.68 (d, J=2.2 Hz 2H), 6.82 (s, 2H), 7.56 (d, J=8.6 Hz, 2H). MS (EI): m/z 318 (M + ). EXAMPLE 4 Preparation of 2,5-bis(4-N,N′-di-BOC-guanidinophenyl)furan derivatives [0071] The following procedures are representative. [0072] 2,5-Bis(4-N,N′-di-BOC guanidinophenyl)furan (Compound 4a). To a room-temperature solution of 2,5-bis(4-aminophenl)furan (0.626 g, 2.5 mmol) and 1,3-bis(tert-butoxycarbonyl)-2-methyl-2-thiopseudourea (1.56 g, 5.3 mmol) in anhydrous DMF was added triethylamine (1.59 g, 15.7 mmol) followed by mercury(II) chloride (1.57 g, 5.8 mmol) and the resulting suspension was stirred at room-temperature for 22 hours. After diluting with CH 2 Cl 2 and sodium carbonate solution, the suspension was filtered over Celite and the filtrate was washed well with water (3×) and finally with brine. After drying (Na 2 SO 4 ), the solvent was removed in vacuo and the residue was diluted with MeOH to give the BOC-protected bis-guanidine as a pale yellow solid. The collected product was purified by reprecipitation from CH 2 Cl 2 /MeOH to give a fluffy yellow solid (1.25 g, 68%), mp>400° C. dec. 1 H NMR (CDCl 3 ): 1.50 and 1.53 (2s, 36H), 6.65 (s, 2H), 7.66 (s, 8H), 10.38 (br s, 2H), 11.61 (br s,2H). [0073] 2,5-Bis(2-methyl-4-N,N′-di-BOCguanidinophenyl)furan (Compound 4b). Yellow solid, mp>250° C. dec. Yield: 62%. 1 H NMR (CDCl 3 ): 1.51 and 1.52 (2s, 36H), 2.53 (s, 6H), 6.60 (s, 2H), 7.40 (s, 2H), 7.62 (d, 2H), 7.74 (d, 2H), 10.34 (s, 2H), 11.62 (br s, 2H). [0074] 2,5-Bis(2-methoxy-4-N,N′-di-BOCguanidinophenyl)furan (Compound 4c). Yellow solid, mp>300° C. dec. Yield: 79%. 1 H NMR (CDCl 3 ): 1.50 and 1.53 (2s, 36H), 3.95 (s, 6H), 6.95 (s, 2H), 7.13 (d, 2H), 7.59 (s, 2H), 7.86 (d, 2H), 10.36 (s, 2H), 11.55 (br s, 2H). [0075] 2,5-Bis(2-chloro-4-N,N′-di-BOCguanidinophenyl)furan (Compound 4d). Pale yellow/tan solid, mp>400° C. dec. Yield: 63%. 1 H NMR (CDCl 3 ): 1.52 (s, 36H), 7.17 (s, 2H), 7.63 (dd, 2H), 7.79 (d, 2H), 7.38 (d,2H), 10.43 (s, 2H), 11.59 (br s, 2H). [0076] 2,5-Bis(2-trifluoromethyl-4-N,N′-di-BOC guanidinophenyl)furan (Compound 4e). Bright orange solid. Yield: 88%. 1 H NMR (CDCl 3 ): 1.51 and 1.53 (2s, 36H), 6.77 (s, 2H), 7.82 (d, 2H), 7.94 (s, 2H), 8.00 (d, 2H), 10.52 (s, 2H), 11.59 (br s, 2H). [0077] 2,5-Bis(2,6-dimethyl-4-N,N′-di-BOC guanidinophenyl)furan (Compound 4f). Pale yellow/off-white solid, mp>300° C. dec. Yield: 89%. 1 H NMR (CDCl 3 ): 1.51 and 1.53 (2s, 36H), 2.23 (s, 12H), 6.31 (s, 2H), 7.33 (s, 4H), 10.27 (s, 2H), 11.63 (br s, 2H). EXAMPLE 5 Deprotection: of N,N′-di-BOC guanidines [0078] The following procedures are representative, and are further illustrated in FIG. 1 . [0079] 2,5-Bis(4-guanidinophenyl)furan dihydrochloride (Compound 5a). A solution of the corresponding N,N′-di-BOCguanidine (1.19 g, 1.62 mmol) in CH 2 Cl 2 (15 ml) was diluted with dry EtOH (10 ml) and saturated at ice-water bath temperature with anhydrous HCl. The solution was then stirred at room-temperature for 2-3 days (drying tube), with the product slowly precipitating (shorter reaction times generally gave incomplete deprotection). The resulting suspension was concentrated to near dryness, with the solid then taken up in hot EtOH. After filtering to clarify, the solution was concentrated to near dryness to give a suspension, which was diluted with ether and collected to yield, after drying in vacuo at 50-60° C. for 2 days, the bis-guanidine dihydrochloride as an off-white/tan solid (0.66 g, quantitative), mp>300° C. dec. 1 H NMR (DMSO-d 6 ): 7.12 (s, 2H), 7.31 (d, 4H), 7.58 (br s, 8H), 7.86 (d, 4H), 10.09 (br s, 2H). MS (FAB, thioglycerol): m/z 335.3 (MH + , 100). Anal. Calcd. for C 18 H 18 N 6 O.2HCl.0.25EtOH (407.30): C, H, N. [0080] 2,5-Bis(4-guanidino-2-methylphenyl)furan dihydrochloride (Compound 5b). Tan solid, mp 265-271° C. dec. 1 H NMR (DMSO-d 6 ): 2.53 (s, 6H), 6.93 (s, 2H), 7.17 (m, 4H), 7.56 (br s, 8H), 7.82 (d, 2H), 10.06 (br s, 2H). MS (FAB, thioglycerol): m/z 363.3 (MH + , 100). Anal. Calcd. for C 20 H 22 N 6 O.2HCl.1.5H 2 O.0.66EtOH (496.93): C, H, N. [0081] 2,5-Bis(4-guanidino-2-methoxyphenyl)furan dihydrochloride (Compound 5c). Light brown solid. 1 H NMR (DMSO-d 6 ): 3.95 (s, 6H), 6.92 (dd, 2H), 6.99 (d, 2H), 7.02 (s, 2H), 7.58 (br s, 8H), 7.95 (d, 2H), 10.08 (br s, 2H). MS (EI): m/z 352 (M + -NH 2 CN, 38.0), 310 (100), 267 (38.9), 251 (8.8), 155 (18.7). Anal. Calcd. for C 20 H 22 N 6 O 3 .2HCl.1.0H 2 O.0.33EtOH (500.57): C, H, N. [0082] 2,5-Bis(2-chloro-4-guanidinophenyl)furan dihydrochloride (Compound 5d). Tan solid, mp 300-304° C. dec. 1 H NMR (DMSO-d 6 ): 7.31 (s, 2H), 7.33 (d, 2H), 7.47 (s, 2H), 7.72 (br s, 8H), 8.04 (d, 2H). MS (DCI, ammonia): m/z 365, 363, 361 (MH + —NH 2 CN, 8, 52, 78), 323, 321, 319 (11, 66, 100). Anal. Calcd. for C 18 H 16 Cl 2 N 6 O.2HCl.0.5H 2 O (485.21): C, H, N, Cl. [0083] 2,5-Bis(4-guanidine-2-trifluoromethylphenyl)furan dihydrochloride (Compound 5e). Orange/red solid. 1 H NMR (DMSO-d 6 ): 6.99 (s, 2H), 7.63 (d, 2H), 7.69 (s, 2H), 7.79 (br s, 8H), 7.91 (d, 2H), 10.37 (br s, 2H). MS (CI, isobutane): m/z 471 (MH + , 14), 429 (100), 387 (19). Anal. Calcd. for C 20 H 16 F 6 N 6 O.2HCl.0.67H 2 O.0.67EtOH (586.24): C, H, N. [0084] 2,5-Bis(4-guanidino-2,6-dimethylphenyl)furan dihydrochloride (Compound 5f). Off-white solid. 1 H NMR (DMSO-d 6 ): 2.20 (s, 12H), 6.56 (s, 2H), 7.01 (s, 4H), 7.57 (br s, 8H), 10.09 (br s, 2H). MS (FAB, thioglycerol): m/z 391.2 (MH + , 100). Anal. Calcd. for C 22 H 26 N 6 O.2HCl.0.5H 2 O (472.41): C, H, N. EXAMPLE 6 Preparation of 2-[5(6)-Amidino-2-benzimidazoyl]-5-(4-nitrophenyl)furan [0085] A mixture of 5-(4-nitrophenyl)furfural (0.651 g, 0.003 mol), 4-amidino-1,2-phenylenediamine (0.614 g, 0.003 mol) and 1,4-benzoquinone (0.324 g, 0.003 mol) in 40 ml of ethanol (under nitrogen) was heated at reflux for 8 h. The volume of the reaction mixture was reduced to 20 ml under reduced pressure, cooled and the resultant solid was collected by filtration. The solid was washed with cold ethanol and ether. The product was dried to yield the mono hydrochloride salt 0.8 g (70%). The mono salt (0.65 g) was dissolved in 120 ml of ethanol and acidified with HCl-saturated ethanol and after standing overnight in a refrigerator the resultant solid was filtered, washed with ether and dried for 24 h in a vacuum oven at 70° C. to yield 0.6 g (85%) mp 300° C. 1 H NMR (DMSO-d 6 ): 9.3 (br s, 2H), 9.09 (br s, 2H), 8.33 (d, J=7.6 Hz, 2H), 8.20 (d, J=7.6 Hz 2H), 8.19 (s,1H), 7.79 (d, J=8.4 Hz, 1H), 7.73 (d, J=8.4 Hz, 1H),7.56 (d, J=3.6 Hz, 1H), 7.51 (d, J=3.6 Hz 1H). 13 C NMR (DMSO-d 6 ): 165.9, 152.6, 146.4, 145.4, 145.3, 141.6, 138.7, 134.7, 124.6, 124.0, 122.1, 121.5, 116.0, 114.6, 114.0, 111.9. FABMS m/e 348(M + +1). Anal. Calcd for C 18 H 13 N 5 O 3 .2HCl.: C, 51.44; H, 3.59; N, 16.66. Found: C, 51.24; H, 4.03; N, 16.92. EXAMPLE 7 Preparation of 2-[5(6)-amidino-2-benzimidazoyl]-5-(4-aminophenyl)furan [0086] The above nitro analog (0.5 g, 0.0013 mol) and 0.3 g of 10% Pd/C in 130 ml of methanol was subjected to hydrogenation at 50 psi for 4 h. The catalyst was removed by filtration over filteraid and the solvent was removed under reduced pressure. The solid was taken up in methanolic HCl, warmed on a water bath for 0.5 h and the solvent was removed under reduced pressure. The residue was treated with ether and the solid was collected by filtration and dried under vacuum at 75° C. for 12 h to yield 0.44 g (73%) mp>360° C. 1 H NMR (DMSO-d 6 /D 2 O): 8.07 (d, J=1.6 Hz, 1H), 7.74(d, J=8.4 Hz, 2H), 7.66 (dd, J=1.6 and 8.4 Hz 2H), 7.39 (d, J=3.6 Hz, 1H), 6.91 (d, J=3.6 Hz, 1H),6.89 (d, J=8.4 Hz, 2H), 13 C NMR (DMSO-d 6 /D 2 O): 166.2, 156.7, 145.8, 142.0, 141.0, 138.1, 126.2, 123.2, 122.3, 119.2, 116.6, 116.0, 115.1, 107.5. FABMS m/e 318(M + +1). Anal. Calcd. for C 18 H 15 N 5 O.3HCl.2H 2 O: C, 43.59; H, 6.09; N, 16.92. Found: C, 43.71, H, 6.01, N, 16.81. EXAMPLE 8 Preparation of 2-[5(6)-{2-imidazolinyl}-2-benzimidazoyl]-5-(4-nitrophenyl)furan [0087] A mixture of 5-(4-nitrophenyl)furfural (0.434 g, 0.002 mol), 4-(2-imidazolinyl)-1,2-phenylenediamine hydrochloride hydrate (0.461 g, 0.002 mol) and 1,4-benzoquinone (0.216 g, 0.002 mol) in 40 ml of ethanol (under nitrogen) was heated at reflux for 8 h. The volume of the reaction mixture was reduced to 20 ml under reduced pressure, cooled and the resultant solid was collected by filtration. The solid was washed with cold ethanol and ether. The product was dried to yield 0.52 g (63%). The compound was dissolved in 200 ml of ethanol and acidified with HCl-saturated ethanol and was stirred at room temperature for 3 h. The mixture was cooled on ice and the solid was filtered, washed with ether and dried for 24 h in a vacuum oven at 75° C. to yield 0.51 g (90%) mp>300° C. 1 H NMR (DMSO-d 6 /D 2 0): 8.31 (d, J=8.4 Hz, 2H), 8.30 (s, 1H), 8.15 (d, J=8.4 Hz, 2H), 7.81 (s, 2H), 7.52 (d, J=4.0 Hz, 1H), 7.46 (d, J=4.0 Hz, 1H), 4.03 (s,4H). 13 C NMR (DMSO-d 6 /D 2 0): 165.6, 153.1, 146.8, 145.7, 145.2, 134.7, 124.9, 124.2, 122.8, 116.9, 115.8, 115.1, 115.0, 112.1, 105.6, 104.7, 44.2. FABMS m/e 374 (M + +1). Anal. Calcd for C 20 H 15 N 5 O 3 .2HCl: C, 53.82; H, 3.88, N, 15.69. Found: C, 53.94; H, 3.93; N, 15.84. EXAMPLE 9 Preparation of 2-[5(6)-{2-imidazolinyl}-2-benzimidazoyl]-5-(4-aminophenyl)furan [0088] The mono hydrochloride salt of the above nitro analog (0.5 g, 0.0013 mol) and 0.2 g of 10% Pd/C in 130 ml of methanol was subjected to hydrogenation at 50 psi for 4 h. The catalyst was removed by filtration over filteraid, washed with warm methanol. The solvent volume was reduced to approximately half under reduced pressure. The flask containing the solution was placed in an ice bath and saturated with HCl gas. The mixture was stirred at room temperature for 4 h and treated with dry ether and the solid was collected by filtration. The solid was dried under vacuum at 75° C. for 24 h to yield 0.55 g (86%) mp>300° C. 1 H NMR (DMSO-d 6 /D 2 0): 8.24 (d, J=1.2 Hz 1H), 7.88 (d, J=8.0 Hz, 2H), 7.80 (s, 2H), 7.51(d, J=3.6 Hz, 1H), 7.21 (d, J=8.4 Hz, 2H),7.10 (dd, J=1.2,3.6 Hz, 1H), 4.0 (s,4H). 13 C NMR (DMSO-d 6 /D 2 0): 165.8, 156.4, 145.8, 142.0, 140.9, 137.9, 126.2, 123.7, 121.0, 117.0, 116.8, 115.3, 108.5, 44.6. FABMS m/e 344(M + +1). Anal. Calcd for C 20 H 17 N 5 O.3HCl 2 .1H 2l O: C, 48.96; H, 4.97; N, 14.27. Found: C, 48.58; H, 4.32; N, 14.27. EXAMPLE 10 Preparation of 2-[5(6)-{N-isopropylamidino}-2-benzimidazoyl]-5-(4-nitrophenyl)furan [0089] A mixture of 5-(4-nitrophenyl)furfural (0.434 g, 0.002 mol), 4-N-isopropylamidino-1,2-phenylenediamine hydrochloride hydrate (0.493 g, 0.002 mol) and 1,4-benzoquinone (0.216 g, 0.002 mol) in 40 ml of ethanol (under nitrogen) was heated at reflux for 6 h. The volume of the reaction mixture was reduced to about 15 ml under reduced pressure, the mixture was cooled and the resultant solid was collected by filtration to yield the mono hydrochloride salt 0.66 g (80%). The mono salt was dissolved in 100 ml of ethanol and acidified with HCl-saturated ethanol and after cooling in an ice bath the resultant solid was filtered, washed with ether and dried for 24 h in a vacuum oven at 75° C. to yield 0.7 g (91%) mp>300° C. 1 H NMR (DMSO-d 6 /D 2 0): 8.26 (d, J=8.8 Hz, 2H), 8.11 (d, J=8.8 Hz 2H), 8.01 (d, J=1.2 Hz, 1H), 7.77 (d, J=8.8 Hz, 1H), 7.59 (dd, J=1.2, 8.8 Hz, 1H),7.50(d, J=7.6 Hz, 1H), 7.42 (d, J=7.6 Hz 1H),4.04 (septet, J=6.8 Hz,1H), 1.3(d, J=6.8 Hz,6H). 13 C NMR (DMSO-d 6 ): 162.7, 153.8, 147.2, 145.2, 144.8, 140.7, 138.2, 135.2, 125.4, 124.7, 124.0, 123.5, 116.3, 115.9, 115.3, 112.6, 45.6, 21.4. FABMS m/e 376(M + +1). Anal. Calcd for C 21 H 19 N 5 O 3 .2HCl.2.0H 2 O: C, 49.71; H, 5.16; N. 13.80. Found: C, 49.65; H, 5.11; N, 13.50. EXAMPLE 11 2-[5(6)-N-isopropylamidino-2-benzimidazoyl]-5-(4-aminophenyl)furan [0090] The mono hydrochloride salt of the above nitro analog (0.411 g, 0.001 mol) and 0.3 g of 10% Pd/C in 120 ml of methanol was subjected to hydrogenation at 50 psi for 4 h. The catalyst was removed by filtration over filteraid, washed with warn methanol. The solvent volume was reduced to approximately half under reduced pressure. The flask containing the solution was placed in an ice bath and saturated with HCl gas. The mixture was stirred at room temperature for 4 h and treated with dry ether and the solid was collected by filtration. The solid was dried under vacuum at 80° C. for 24 h to yield 0.41 g (87%) mp>300° C. 1 H NMR (DMSO-d 6 /D 2 0): 8.04 (d, J=1.6 Hz, 1H), 7.91 (d, J=8.4 Hz 2H), 7.80 (d, J=8.4 Hz 1H), 7.64 (dd, J=1.6,8.4 Hz, 1H), 7.60 (d, J=4.0 Hz, 1H),7.24(d, J=8.4 Hz, 2H), 7.14 (d, J=4.0 Hz 1H),4.05 (septet, J=6.4 Hz,1H), 1.3(d, J=6.4 Hz,6H). 13 C NMR (DMSO-d 6 ): 162.4, 156.8, 144.4, 140.9, 138.8, 137.6, 135.0, 126.3, 125.4, 124.6, 124.1, 121.1, 118.0, 115.6, 114.9, 108.6, 45.6, 21.3. FABMS m/e 360(M + +1). Anal. Calcd for C 21 H 21 N 5 O 3 .3HCl: C, 53.80; H, 5.15; N, 14.93. Found: C, 54.22; H, 4.75; N, 15.05. EXAMPLE 12 2,5-Bis(2-Benzimidazolyl-4-cyanophenyl)furan [0091] A mixture of 5-[4-cyanophenyl]-2-furancarboxaldehyde (1.97, 0.01 mol), 1,2-phenylenediamine (1.06 g, 0.01 mol) and 1,4-benzoquinone (1.08 g, 0.01 mol) in 50 ml dry ethanol was heated at reflux (under nitrogen) for 8 h. The reaction mixture was cooled and diluted with ether and filtered. The solid was collected and stirred with 1:3 mixture of EtOH and ether for 20 min and the yellow brown solid was filtered, washed with ether and dried in vacuum at 70° C. for 12 h. which yielded 1.96 g (69%), mp 227-8° C. dec, 1 H-NMR(DMSO-d6): 8.06 (d, 2H, J=8.8 Hz), 7.91(d, 2H,J=8.8 Hz), 7.60 (dd, 2H, J=3.2 Hz, J=6.4 Hz), 7.38 (d, 1H, J=3.6 Hz), 7.32(d, 1H, J=3.6 Hz), 7.23 (dd, 2H, J=3.2 Hz, J=6.4 Hz). 13 C-NMR(DMSO-d6): 152.1, 146.0, 142.7, 138.7, 133.2, 132.6, 124.1, 122.3, 118.4, 114.9, 112.5, 111.1, 109.8, MS: m/e 285 (M + ). Anal. calcd. for: C18H11N3O: C, 75.79; H, 3.86; N, 14.73. Found: C, 75.88; H, 3.77; N, 14.55. 2,5-Bis[2-Benzimidazolyl-4-(amidino)phenyl]furan dihydrochloride [0092] The above cyano compound (2.85 g, 0.01 mol) in 60 ml ethanol was saturated with dry HCl gas at 0-5° C. The reaction mixture was stirred at room temperature for 12 days (monitored by IR and TLC). The mixture was diluted with ether and the yellow imidate ester hydrochloride was filtered, washed with ether and dried under vacuum for 6 h 3.73 g (92%). The solid was used in next step without further purification. A suspension of the imidate ester hydrochloride (0.808 g, 0.002 mol) in 35 ml ethanol was saturated with ammonia gas at 0-5° C. and stirred for 24 h at room temperature. The solvent was reduced to one-third under reduced pressure, diluted with ether and filtered. The yellow solid was resuspended in 10 ml ethanol and treated with 4 ml saturated ethanolic HCl and stirred at 35° C. for 2 h. The solvent was removed under vacuum and the residue triturated with ether, filtered, washed with ether and dried under vacuum at 45° C. for 24 h to yield 0.61 g (81%). yellow solid mp>280° C. dec. 1 H-NMR(DMSO-d6/D2): 8.15(d, 2H, J=8.7 Hz), 7.93 (d, 2H, J=8.7 Hz), 7.78 (d, 1H, J=3.6 Hz), 7.75 (dd, 2H, J=3 Hz, J=6.3 Hz), 7.50 (d, 1H, J=3.6 Hz), 7.49 (dd, 1H, J=3 Hz, J=6.3 Hz). 13 C-NMR(DMSO-d6): 165.0, 155.9, 139.8, 139.7, 133.4, 132.4, 129.3, 127.8, 126.3, 125.2, 119.5, 114.3, 112.0. FABMS: m/e 303 (M + +1). Anal. calcd. for: C18H14N4O.2HCl: C,57.61; H,4.29; N, 14.93. Found; C, 57.45; H, 4.46; N, 14.64. 2,5-Bis[2-Benzimidazolyl4-(2-imidazolino)phenyl]furan dihydrochloride [0093] A mixture of the imidate ester hydrochloride (0.808 g, 0.002 mol) from above, ethylenediamine (0.12 g, 0.002 mol) in 20 ml of dry ethanol was heated at reflux for 12 h. The solvent volume was reduced to 8 ml under reduced pressure and diluted with ether. The resultant solid was filtered and dried. This solid was dissolved in 35 mL hot ethanol and saturated with HCl gas at room temperature. The mixture was stirred at 50° C. for 2 h and concentrated under reduced pressure and 30 ml dry ether was added. The precipitated yellow salt was filtered, washed with ether and dried under vacuum at 70° C. for 24 h to yield 0.69 g (84%) yellow solid mp>300° C. dec. 1 H-NMR(DMSO-d6/D2): 8.06(d, 2H, J=8.7 Hz), 7.91 (d, 2H, J=8.7 Hz), 7.71 (dd, 2H, J=3 Hz, J=6 Hz), 7.64 (d, 1H, J=3.9 Hz), 7.47(dd, 1H, J=3 Hz, J=6.3 Hz), 7.44 (d, 1H, J=3.9 Hz), 3.94 (s, 4H). 13 C-NMR(DMSO-d6): 164.6, 155.7, 140.3, 140.1, 133.9, 132.9, 129.7, 126.7, 125.4, 122.1, 119.2, 114.6, 112.5, 44.8, FABMS: m/e 303 (M++1). Anal. calcd for: C20H16N4O.2HCl.0.5H2O: C,58.54; H,4.67; N, 13.65. Found; C, 58.54; H, 4.67; N, 13.66. EXAMPLES 13-24 [0094] Anti-BVDV Properties of Inventive Compounds EXAMPLE 13 [0095] Screening of Antiviral Compounds for Anti-BVDV Activity [0096] 2.0 cm 2 wells in a 24-well plate were seeded with 50 μl of medium from 12 ml of MEM-eq (minimum essential medium (MEM) with Earle's salts supplemented with 10% (v/v) equine serum, sodium bicarbonate (0.75 mg/ml), L-glutamine (0.29 mg/ml), penicillin G (100 U/ml), streptomycin (100 μg/ml), and amphotericin B (0.25 μg/ml)), which was derived by trypsinization of a confluent monolayer of Madin Darby Bovine Kidney (MDBK) cells in a 25 cm 2 flask. Cells were incubated at 38.5° C. with 5% CO 2 for 24 hours. The average number of cells per well was determined and later used to calculate appropriate multiplicities of infection (MOI) of BVDV virus. [0097] Cells were inoculated with BVDV in medium containing test antiviral compounds (12.5 μM, 200 μL total volume), as follows: [0098] two wells had no BVDV, and no antiviral compound [0099] one well had BVDV at 0.05 MOI, and no antiviral compound [0100] one well had BVDV at 1.0 MOI, and no antiviral compound [0101] ten wells had BVDV at 0.05 MOI, and 12.5 μM of antiviral compound [0102] ten wells had BVDV at 1.0 MOI, and 12.5 μM of antiviral compound. [0103] The inoculated cells incubated for one hour at 38.5° C. with 5% CO 2 in humidified air. The medium was removed from the wells, and the cells washed one time with Ca 2+ and Mg 2+ -free PBS comprising antiviral compound (12.5 μM) (cells in the wells not initially treated with antiviral compounds were washed without antiviral compound). One ml of MEM-eq comprising antiviral compound (12.5 μM) was added to wells initially treated with antiviral compound; those not treated with antiviral compound initially did not receive antiviral compound at this step. Three days post-inoculation, medium was removed and stored at −20° C. for assay. One ml of fresh medium containing 200 μL total (12.5 μM) antiviral compound was is added to wells initially treated with antiviral compound; those not treated with antiviral compound initially did not receive antiviral compound at this step. Seven days post-inoculation, medium was removed and stored at −80° C. for serial dilution & assay. [0104] The MDBK cells were resuspended in MEM-eq with no antiviral compound. Uterine tubal cells (UTC) were freeze-thawed and stored at −80° C. for analysis. UTC lysates were serially diluted with medium from Day 7 and assayed by immunoperoxidase for the presence of BVDV. EXAMPLE 14 [0105] Immunoperoxidase Monolayer Assay for BVDV [0106] All samples were assayed for BVDV using the immunoperoxidase monolayer assay as described in A. Afshar et al., Can J Vet Res; 55:91-93 (1991). Samples were assayed in triplicate by adding 50 μL of MEM-eq containing approximately 2.5×10 MDBK cells to 50-μL of each sample supplemented with 50 μL of fresh MEM-eq in a 96-well culture plate. Plates were incubated for 72 h at 38.5° C. in a humidified atmosphere of 5% CO2 and air before the immunoperoxidase labeling technique was performed as follows: [0107] After fixation, potentially infected cells were incubated with monoclonal antibodies D89 (M. L. Vickers et al., J Vet Diagn Invest 2, 300-302 (1990); Xue W et al., J Clin Microbiol 28, 1688-1693 (1990)) specific for E2/gp53, a major envelope glycoprotein of BVDV (Xue W et al., Vet Microbiol 57, 105-118 (1997)) and 20.10.6 specific for NS3-p80, a conserved nonstructural protein (W. V. Corapi et al., Am J Vet Res 51, 1388-1394 (1990)). After washing with PBS and Tween 20 to remove unbound antibodies, peroxidase-conjugated rabbit anti-mouse IgG (Jackson Immuno Research Lab, West Grove, Pa.) was added. After a short incubation period, unbound peroxidase-conjugated antibody was removed by washing with PBS and Tween 20. Finally, the enzyme substrate, aminoethyl carbazole (Zymed Laboratories, Inc., South San Francisco, Calif.), which produces a reddish-brown color when oxidized by horseradish peroxidase, was added. Color change was visualized under light microscopy and compared to known positive and negative controls on each plate. EXAMPLE 15 [0108] Tissue Culture Passage [0109] All samples other than stock virus aliquots were also passaged in tissue culture to optimize isolation of BVDV. Upon initial thawing, 200 μL of each sample was inoculated onto a 2 cm 2 well seeded 24 h previously with MDBK cells. Passages were incubated 5 days (d) at 38.5° C. in an atmosphere of 5% CO 2 and humidified air. Passages were frozen at −80° C. for storage. Tissue culture passage samples were thawed and assayed by virus isolation if isolation of BVDV was unsuccessful from the original sample. Samples were reported to be free of BVDV by virus isolation only if virus was not detected after each of two serial passages. EXAMPLE 16 [0110] Reverse Transcription Nested Polymerase Chain Reaction Assay (RT-nPCR) [0111] A reverse transcription nested polymerase chain reaction assay for detecting BVDV was performed on all samples other than stock virus aliquots. Upon initial thawing, RNA was isolated from samples using the QIAamp® viral RNA mini kit (Qiagen, Valencia, Calif.) according to the manufacturer's instructions. RNA samples were stored at −80° C. until RT-nPCR was performed. [0112] All steps of complementary DNA production (cDNA) and amplification were carried out in a single closed-tube reaction using a modification of the protocol of McGoldrick et al. (see Duffell S J et al., Vet Rec 1985;117:240-245; Givens M D, et al., Theriogenology 2000;54:1093-1107; Lang-Ree J R, et al., Vet Rec 1994;135:412-413). In the first step, 5 μL of trehalose (22% w/v stock; Sigma, St Louis, Mo., cat #T5251) was used to store and maintain the following mixture in the lid of a 200-μL, thin-walled tube: 0.4 μL of each inner primer BVD 180 and HCV 368 (50 μM), 1 μL of dNTPs (10 mM) and 0.25 μL of Taq Polymerase (1.25 U, Promega, Madison, Wis.). The tubes were left to dry for 2 h at room temperature prior to storage. [0113] In the second step, the initial reverse transcription polymerase chain reaction was performed in the bottom of the tubes containing the dried trehalose mixture within the lid. Two μL of RNA were added through the overlaid mineral oil (50 μL) to the initial reaction volume (48 μL) containing the following reagents (Promega): 5 μL 10× buffer, 8 μL of MgCl2 (25 mM), 2 μL of dNTPs (10 mM), 1 μL of each outer primer BVD 100 and HCV 368 (5 μM), 1 μL of Triton X-100 (100% stock), 0.25 μL of dithiothreitol (100 mM), 0.25 μL (10 U) RNAsin, 0.5 μL (2.5 U) of Taq polymerase, and 0.5 μL (100 U) of MMLV (Moloney Murine Leukemia Virus) reverse transcriptase. The tubes were then subjected to the following cycle parameters: 37° C. for 45 min, 95° C. for 5 min and then 20 cycles at 94° C. for 1 min, 55° C. for 1 min and 72° C. for 1 min. [0114] A final elongation step of 72° C. for 10 min completed the initial amplification reaction. In the third step, the tubes were inverted several times to mix the samples in the lid and in the base to initiate the nested polymerase chain reaction (nPCR). The tubes were then centrifuged at 14,000×g for 12 sec before returning to the thermocycler for nPCR, using 30 cycles of 94° C. for 1 min, 55° C. for 1 min and 72° C. for 45 sec. A final elongation step of 72° C. for 10 min completed the amplification process prior to maintaining the reactions at 4° C. Five microliter aliquots of PCR products were separated by 1.5% agarose gel electrophoresis. The agarose gels contained 0.5 μg/ml ethidium bromide to allow visualization of RT-nPCR products using an ultraviolet transilluminator. [0115] The outer primers, BVD 100 (5′-GGCTAGCCATGCCCTTAG-3′) (SEQ ID NO. 1) and HCV 368 (5′-CCATGTGCCATGTACAG-3′) (SEQ ID NO. 2) amplified a 290 base pair sequence of the 5′ untranslated region of the viral genome. The inner primers, BVD 180 (5′-CCTGAGTACAGGGDAGT CGTCA-3′) (SEQ ID NO. 3) and HCV 368 amplified a 213 base pair sequence within the first amplicon. The novel BVD 180 primer was degenerate at the 14th base (D=G+A+T) to accommodate differences within the 5′ untranslated sequences of virus strains used in this research as determined by automated dye terminator nucleotide sequencing (Nucleic Acid Resource Facility, Auburn University, Ala.) of the initial PCR products from viral stocks. EXAMPLE 17 [0116] Oocyte Collection and Maturation [0117] Cow ovaries were collected at an abattoir in Omaha, Neb., and placed in PBS for transport to a nearby laboratory. The contents of 1- to 10-mm follicles were aspirated at a vacuum rate of 21.5 ml/min and poured onto a 70 μm filter. Cellular components of the pooled follicular aspirate were rinsed with TL-HEPES and searched for oocytes surrounded by multiple layers of dense cumulus cells. Useable cumulus oocyte complexes (COCs) were washed two additional times in TL-HEPES, then placed in 7.5 ml of maturation media that had previously equilibrated at 38.5° C. in an atmosphere of 5% CO 2 and humidified air. The maturation media was then sealed and maintained at 38.5° C. for 20 to 22 h while being transported to the experimental laboratory. EXAMPLE 18 [0118] Media for in vitro Fertilization/Embryo Assays [0119] Oocytes were matured in cell culture medium 199 (CCM 199) with Earle's salts (GIBCO-BRL, Grand Island, N.Y., USA) supplemented with 10% (v/v) heat-inactivated fetal bovine serum (FBS; HyClone Lab., Inc., Logan, Utah, USA), sodium pyruvate (11 μg/ml), bovine FSH (0.01 U/ml), bovine LH (0.01 U/ml), penicillin (100 U/ml) and streptomycin (100 μg/ml). [0120] Matured oocytes were fertilized in CR2 medium (C. F. Rosenkrans et al., Theriogenology 35, 266 (1991)) supplemented with BSA (6 mg/ml), heparin (10 μg/ml), penicillamine (0.3 μg/ml), hypotaurine (0.2 μg/ml), penicillin (100 U/ml) and streptomycin (100 μg/ml). [0121] The first three days (d) of in vitro culture (IVC) was in CR2 medium supplemented with BSA (6 mg/ml), penicillin (100 U/ml) and streptomycin (100 μg/ml). The last four d of IVC was in CR2 medium supplemented with 10% (v/v) FBS, penicillin (100 U/ml) and streptomycin (100 μg/ml). EXAMPLE 19 [0122] Exposure to Bovine Viral Diarrhea Virus (BVDV) [0123] After in vitro maturation (IVM), COCs were washed 5 times in 3 ml of MEM-eq. After washing, COCs were exposed to a noncytopathic strain of BVDV in 3 ml of MEM-eq or maintained separately as negative controls in BVDV-free MEM-eq. Exposed and unexposed COCs were incubated for 1 h at 38.5° C. in an atmosphere of 5% CO2 and humidified air, and then washed 3 times in 3 ml of TL-HEPES before addition to IVF drops. [0124] The noncytopathic strains of BVDV used in this research included 2 diverse Genotype I strains (SD-1 and NY-1) and 2 diverse Genotype II strains (CD-87 and PA-131). Givens M D et al., Theriogenology 2000;54:1093-1107. All stocks were propagated in BVDV-free MDBK cells cultured in MEM-eq. Virus was harvested by freezing and thawing and was'stored in cryovials at −80° C. until needed. EXAMPLE 20 [0125] In vitro Fertilization [0126] Matured COCs were placed in 42-μL drops of fertilization medium under mineral oil. Cryopreserved bovine semen from a single collection was used for fertilization. This semen was confirmed to be free of BVDV by virus isolation and RT-nPCR. After PERCOLL®-gradient (45 to 90%) separation, 1.5×10 5 spermatozoa were added to each fertilization drop, which was incubated for approximately 18 h at 38.5° C. in a humidified atmosphere of 5% CO 2 and air. EXAMPLE 21 [0127] In vitro Culture [0128] After the IVF period, presumptive zygotes were removed, washed 4 times in TL-Hepes, equilibrated in IVC medium with BSA, and placed with cumulus cells still attached in 30-μl drops (10 to 12 per drop) of the IVC medium with BSA under mineral oil. The IVC plates were incubated for 3 d at 38.5° C. in a humidified atmosphere of 5% CO 2 and air. After the first 3 d in IVC, embryos were washed 3 times in TL-Hepes, and most of the cumulus cells were removed by gentle aspiration in and out of a sterile pipette. The nearly nude embryos were examined for cleavage, and those at the 5-cell stage or greater were washed 1 more time in IVC medium and placed with pieces of detached cumulus in 60-μl drops (20 to 25 per drop) of the IVC medium with 10% (v/v) FBS under mineral oil. These developed embryos were incubated an additional 4 d. After the final 4 d in IVC, embryos were transferred into 3 ml of MEM-eq, separated from cumulus cells, and development to the morula or blastocyst stage was noted. EXAMPLE 22 [0129] Washing and Trypsin Treatment of Embryos [0130] Washing and trypsin treatment of Day 7 embryos conformed to procedures recommended by the International Embryo Transfer Society for treatment of in vivo-derived bovine embryos. (Stringfellow D A, et al., Manual of the International Embryo Transfer Society Third Edition., Savoy Ill.: International Embryo Transfer Society, 1998;79-84). Degenerate and developed Day 7 embryos were washed 12 times in 1 ml of MEM-eq in 2-cm2 wells. [0131] For trypsin treatment, twelve 3-ml washes in 35-mm Petri dishes were used. The first 5 and last 5 washes were PBS supplemented with 0.4% BSA, penicillin (100 U/ml) and streptomycin (100 μg/ml). The 6th and 7th washes were trypsin diluted 1:250 in 3 ml of Hank's balanced salt solution without Ca 2+ and Mg 2+ . Embryos were treated in trypsin for approximately 90 sec (45 sec/wash) before proceeding through the last 5 washes. EXAMPLE 23 [0132] Samples Assayed for BVDV [0133] During each of 12 research replicates (3 replicates with 4 diverse strains of BVDV), 140 to 180 COCs were exposed to virus while 50 to 80 COCs were maintained as negative controls. For each replicate, samples were obtained from exposed and unexposed cultures to be assayed for BVDV. All samples other than stock virus aliquots were assayed for BVDV using virus isolation with (a) immunoperoxidase assay for viral detection, (b) tissue culture passage prior to virus isolation to optimize viral detection, and (c) RT-nPCR. Samples included: [0134] Stock virus aliquots. The viral aliquot to which the COCs were exposed was serially diluted and assayed by virus isolation using immunoperoxidase assay. [0135] Day 3 cumulus cells. On Day 3 of IVC, some detached cumulus cells were removed from the 3rd wash of TL-Hepes, transferred into 3 ml of MEM-eq, and then placed in 500 μL of MEM-eq within a cryovial. Cells were lysed by freezing at −80° C. and thawing to release any intracellular virus prior to assay for BVDV. [0136] Day 7 cumulus cells. On Day 7 of IVC, cumulus cells from exposed and unexposed cultures were transferred from the 3 ml of MEM-eq into 500 μL of MEM-eq within a cryovial. Cells were lysed by freezing at −80° C. and thawing to release any intracellular virus prior to assay for BVDV. [0137] Day 7 individual embryos. If sufficient numbers of BVDV-exposed M/B developed by Day 7 of each research replicate, a group of 10 M/B was washed as previously described and a group of 10 M/B was trypsin-treated as previously described. Virus-exposed, washed M/B were individually placed into 500 μL of MEM-eq (4 to 5 per replicate) or were individually cryopreserved and thawed before placement in MEM-eq (4 to 5 per replicate). Virus-exposed, trypsin-treated M/B were individually placed into 500 μL of MEM-eq (3 to 5 per replicate) or were individually cryopreserved and thawed before placement in MEM-eq (4 to 5 per replicate). All samples were sonicated before viral assay. [0138] If sufficient numbers of non-exposed M/B developed by Day 7 of each replicate, a group of 10 M/B was washed as previously described. Non-exposed, washed M/B were individually placed directly into 500 μL of MEM-eq (5 per replicate) or were individually cryopreserved and thawed before placement in MEM-eq (5 per replicate). Samples were sonicated before viral assay. EXAMPLE 24 [0139] Statistical Analysis and Results [0140] The tissue culture infective dose 50% (TCID 50 )/ml of the exposure aliquot was determined by the method of Reed and Muench (L. J. Reed and H. Muench, Am J Hygiene 27, 493-497 (1938). Results of viral detection assays were compared using a Pearson Chi-square test statistic (J. Sall and A. Lehman, JMP Start Statistics (Duxbury Press, Belmont, Calif. (1996), 195-211). [0141] Table 2 sets forth the results of the analysis of in vitro culture media and cell lysates that have been treated with the indicated antiviral compound for the indicated time at a concentration of 12.5 μM, after exposure to BVDV at a MOI of 0.05 (see Example 12). TABLE 2 Day 3 Media Day 7 Media Day 7 Cell Lysates Antiviral drug TCID 50 /mL % Control TCID 50 /mL % Control TCID 50 /mL % Control No antiviral 2.00E+05 5.20E+05 2.00E+06 DB619 3.50E+02 0.18% 2.00E+05 38.46% 1.10E+06 55.00% DB673 1.00E+02 0.05% 6.20E+03  1.19% 3.50E+04  1.75% [0142] Table 3 sets forth the results of the analysis of in vitro culture media and cell lysates that have been treated with the indicated antiviral compound for the indicated time at a concentration of 12.5 μM, after exposure to BVDV at a MOI of 1.0 (see Example 12). TABLE 3 Day 3 Media Day 7 Media Day 7 Cell Lysates Antiviral drug TCID 50 /mL % Control TCID 50 /mL % Control TCID 50 /mL % Control No antiviral 3.50E+05 3.50E+04 6.20E+05 DB619 6.20E+04 17.71% 3.50E+04 100.00% 3.50E+05 56.45% DB673 3.50E+02  0.10% 2.00E+05 571.43% 2.70E+05 43.55% [0143] Table 4, below sets forth the results of the analysis of Day 3 in vitro culture media and Day 3 cell lysate that has been treated with the indicated antiviral compound at a concentration of 12.5 μM, after exposure to BVDV at a MOI of 0.5 (see Example 12). TABLE 4 Day 3 Media Day 3 Cell Lysates Antiviral drug TCID 50 /mL % Control TCID 50 /mL % Control No antiviral 3.50E+06 6.20E+06 DB 457 1.00E+02 0.0029% 3.50E+02 0.0056% DB 458 Negative Negative DB 459 Negative 1.00E+02 0.0016% DB 606 Negative Negative DB 680 Negative Negative DB 701 6.20E+03 0.1771% 3.50E+04 0.5645% DB 705 Negative Negative DB 708 Negative Negative DB 711 2.40E+05 6.8571% 2.00E+07 322.5806%  DB 752 Negative 6.20E+02  0.01% [0144] Table 5 sets forth the results of the analysis of Day 3 cell lysates that have been treated with the indicated antiviral compound for three days at the indicated concentration, after exposure to BVDV at a MOI of 0.05. TABLE 5 Day 3 Media Day 3 Cell Lysates Antiviral drug TCID 50 /mL % Control TCID 50 /mL % Control No antiviral 2.00E+06 3.50E+05 DB 456 25 μm 3.50E+03  0.1750% 2.00E+03 0.5714% DB 456 12 μm 6.20E+02  0.0310% 3.50E+03 1.0000% DB 456 6 μm 3.50E+04  1.7500% 3.50E+04 10.0000% DB 456 3 μm 3.50E+05 17.5000% 6.20E+05 177.1429% DB 456 1.5 μm 5.10E+05 25.5000% 3.50E+06 1000.0000% DB 456 0.7 μm 6.30E+05 31.5000% 3.50E+06 1000.0000% DB 456 0.4 μm 6.30E+05 31.5000% 3.50E+06 1000.0000% DB 456 0.2 μm 6.30E+05 31.5000% 3.50E+05 100.0000% [0145] In the specification, and examples there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purposes of limitation, the scope of the invention being set forth in the following claims.

The present invention relates to novel compounds and methods that are useful in treating members of the Flaviviridae family of viruses. Compounds of the present invention will have a structure according to Formulas (I)-(VI) as recited throughout the application.

FIELD OF THE INVENTION The present invention is directed generally to traffic simulation in telecommunications networks and specifically to traffic simulation in asynchronous transfer mode networks. BACKGROUND OF THE INVENTION The current public switched telephone network (PSTN) was implemented as a highly reliable, robust, and efficient system for transporting voice traffic. The PSTN has now been burdened with additional types of traffic for which the PSTN was not designed to transport (e.g., Internet, file transfer, video, fax, etc.). The current narrowband synchronous transfer mode (STM) telephony system will have to be replaced by or evolve into a broadband network to preserve the integrity of the system and accommodate the new services. The asynchronous transfer mode (ATM) protocol has been selected as the core switching protocol for emerging broadband networks. ATM is an elegant protocol that has the desirable ability to multiplex voice, video, and data and to transmit information on the same communications channel at very high speeds. As used herein, ATM refers to a connection-oriented protocol in which bandwidth is allocated when the originating end user requests a connection. This allows ATM to efficiently support a network's aggregate demand by allocating bandwidth on demand based on immediate user need. Problems have been encountered in modeling traffic on an ATM network, which has complicated the design and analysis of ATM networks. For a network to be properly sized and provisioned, the design engineer must thoroughly understand the traffic load and the behavior of that traffic load over time. Traditionally, STM networks were based on the Poisson model. Random number generators were used to produce streams of numbers, representative of real network interarrival times, and which are based on the Poisson model. However, this model is unable to accurately characterize the “bursty” nature of ATM network traffic. Burstiness is present in a traffic process if the arrival points appear to form visual clusters; that is, the packets have runs of several short interarrival times (i.e., the time interval between the receipt of successive packets at a specified destination from a specific source) followed by a relatively long one. As will be appreciated, voice and video packets in ATM networks are typically given a higher priority than data packets in routing or switching the packets for processing. Accordingly, data packets can have significantly longer packet interarrival times than voice or video packets. Other models have been considered in modeling ATM traffic using random number generators, including the Markov Modulated model, the Transform Expand Sample model, the Autoregressive model, the Fluid model, and the Self-similar model. Although these models have been found to have varying degrees of success for modeling Ethernet traffic (which, like ATM networks, uses a packet-based protocol), they have been largely unsuccessful in characterizing the bursty nature of ATM traffic. The failure of these models is in part due to the differences between ATM networks and other type of packet networks. For example, ATM is a connection-oriented protocol with a fixed length packet size. This contrasts with Ethernet which is a connectionless protocol with variable length packet size. Variable packet sizes give rise to a Gaussian (normal) or exponential probilistic distribution of packet interarrival times. SUMMARY OF THE INVENTION These and other needs are addressed by the methods and systems of the present invention. The present invention is premised on the recognitions (a) that interarrival times of packets in ATM networks can have a lognormal probabilistic distribution; (b) that delayed packets on an ATM network can follow a normal probabilistic distribution; and (c) that packet interarrival times in an ATM network corresponding to data packets alone or to data packets and voice and/or video packets typically have bimodal probabilistic distributions. In one configuration, a probabilistic distribution(s) is defined by a normal or self-similar (Gaussian) model and the other probabilistic distribution(s) is defined by a lognormal model. As used herein, a “network” refers to an architecture having two or more computers (e.g., each of which includes a processor and memory) connected by one or more communication paths (e.g., a local area network (LAN) or wide area network (WAN)). In a typical ATM network, short packet interarrival times (i.e., less than a selected value) define a lognormal probabilistic distribution while long packet interarrival times (i.e., more than a selected value) define a normal probabilistic distribution. In a first embodiment of the present invention, a method for modeling or predicting the performance of (or simulating the traffic in) an ATM network is provided. The ATM network will transport or has transported a stream of packets. The method includes the step of generating (e.g., randomly or psuedorandomly) an at least substantially lognormally distributed set of packet interarrival times corresponding to the plurality of packets. By using lognormal number generators, the methodology of the present invention accurately considers the effect of ATM switch characteristics on traffic behavior. The simulated traffic generated by the algorithm compares closely with traffic on an actual ATM network. For this reason, the algorithm has applications in the areas of ATM switch design, ATM traffic simulation tools, and ATM network design and optimization (particularly the derivation of trunking tables, which are used to size and provision switch trunks). In one configuration, the packet stream also includes a second plurality of packets having normally distributed packet interarrival times. In that event, the method would further include generating (e.g., randomly or pseudorandomly) a normally distributed set of packet interarrival times. In another configuration, the method further includes the steps of (i) multiplying (a) a percentage of the packet stream that corresponds to the plurality of packets and (b) the number of packets in the packet stream to provide the number of packets in the plurality of packets and (ii) multiplying (a) a percentage of the packet stream that corresponds to the second plurality of packets and (b) the number of packets in the packet stream to provide the number of packets in the second plurality of packets. This is a typical step used in modeling an existing or planned ATM network. The total number of packets in the packet stream during a selected time interval can be selected using any technique for characterizing traffic in a communications network, such as busy hour, busy day, busy month, peak call rate, committed burst size, and the like. The number generators can be any algorithm providing output defined by the desired probabilistic distribution (e.g., normal or lognormal probabilistic distributions). In one configuration, the number of generators are random or pseudorandom number generators. In one configuration, the number generators require input such as the number of packets in the plurality of packets (or sample size or vector length) and a mean and a variance of a lognormal distribution characterizing (or believed to characterize) packet interarrival times of the plurality of packets (for the lognormal random number generator) or the number of packets in the second plurality of packets (or second sample size) and a mean and a variance of a normal distribution characterizing (or believed to characterize) packet interarrival times of the packets in the second plurality of packets (for the normal random number generator). As will be appreciated, other techniques may be used to generate lognormal or normal distributions of packet interarrival times including artificially constructed ATM packets (comprising a series of ones and zeros, 58 bytes in length) which have lognormal and normal time interval distributions between packets. In another configuration, the second plurality of packets has a bimodal distribution. This is a common occurrence when voice and/or video packets arrive at different times such that the data packets have a wide range of packet interarrival times. In this configuration, (a) a lognormal fraction of packets in the second plurality of packets having at least substantially lognormally distributed packet interarrival times and (b) a normal fraction of packets in the second plurality of packets having at least substantially normally distributed packet interarrival times are determined. The generating step for the packets in the second plurality of packets is applied to the number of packets in the normal fraction of packets. For the number of packets in the lognormal fraction of packets, the step of generating an at least substantially lognormally distributed set of packet interarrival times such as by using a lognormal random or pseudorandom number generator is provided. In yet another embodiment, a system for characterizing traffic on an ATM network is provided. The system includes lognormal number generating means for generating a plurality of at least substantially lognormally distributed values corresponding to the plurality of packets. In yet a further embodiment, a system for characterizing traffic on an ATM network is provided that includes: (i) a lognormal number generator for generating a plurality of at least substantially lognormally distributed values corresponding to the first plurality of packets; and (ii) a normal number generator for generating a plurality of at least substantially normally distributed values corresponding to the second plurality of packets; and (iii) a combiner, in communication with the lognormal number generator and the normal number generator, for combining the plurality of lognormally distributed values and the plurality of normally distributed values to provide an aggregate stream of values. In yet another embodiment, a method for modeling or predicting packet interarrival times on an ATM network is provided. The method includes the steps of: (i) providing (a) a number of packets in a first portion of a plurality of packets that will be transported or have been transported on an ATM network, the packets in the first portion containing at least one of voice and video information and (b) a number of packets in a second portion of the plurality of packets, the packets in the second portion containing information other than the at least one of voice and video information; (ii) generating with a lognormal number generator a plurality of packet interarrival times values corresponding to at least some of the packets in the first portion; and (iii) generating with a normal number generator a plurality of packet interarrival times corresponding to at least some of the packets in the second portion. The summation or combination of the output of the two types of number generators provides a synthetic traffic stream that closely resembles the actual behavior of the modeled ATM system. The foregoing description of the various embodiments of the present invention is intended to be neither complete nor exhaustive. Those of ordinary skill in the art will appreciate that numerous other embodiments can be envisioned using one or more of the components set forth above. For example, a variety of systems can be envisioned for performing the method steps noted above. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram of an ATM switching architecture; FIG. 2 is a flow diagram of a modeling architecture according to an embodiment of the present invention; FIG. 3 is a flow schematic of software according to another embodiment of the present invention; FIGS. 4A and 4B are plots of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for an ATM network; FIG. 5 is a plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for synthetic data for an ATM network; FIG. 6 is a plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for an ATM network; and FIG. 7 is another plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for synthetic data for an ATM network. DETAILED DESCRIPTION Referring to FIG. 1 , a typical ATM switching architecture is depicted. The ATM switch 10 includes a switch buffer 14 and switch controller 18 . Although an ATM cell or packet in the traffic 22 entering the switch 10 contain bits for discard priority, it is preferable to slow the traffic 22 down rather than degrade the level of service by discarding packets. Flow-control mechanisms in the switch controller 18 limit the arrival rate when the distination buffers become full. In other words, packets which arrive after the buffer is full must wait until buffer space is made available by departing packets. The overflow traffic can thus result in a virtual overflow buffer 26 whose size depends on the transmission speed and buffer size of the switch. As cells are drained away from the buffer 14 , cells waiting in the virtual overflow buffer 26 are admitted to the buffer 14 . A very desirable feature of ATM switches is that they are priority-based and policy-based. Priority-based refers to an ATM switch's capability to assign an admission and transmission priority to an ATM cell based on the type of information it caries (voice, video, or data). Policy-based refers to an ATM switch's capability to assign admission and transmission priority to an ATM cell based on both the type of information it is carrying and the time of day. For example, voice usually has a higher priority than data. However, a switch administrator might want to give data the highest priority for certain hours of the day for example, late at night. Thus, an ATM based network gives network administrators much control over shaping the characteristics of traffic on their networks. Packets passing through the switch can have a broad range of packet interarrival times at their respective destinations. Because voice and video packets have higher admission priority to the switch buffer 14 and much higher sensitivity to delay, packets containing such information typically have short packet interarrival times. In contrast, packets containing information other than voice or video have a lower admission priority to the buffer 14 and will typically have a wide range of packet interarrival times ranging from short interarrival times to long interarrival times, depending on the volume of higher priority packets received by the switch. The broad range of packet interarrival times defines a bimodal probabilistic distribution. The packets having shorter interarrival times define a substantially lognormal probabilistic distribution while those having longer interarrival times define a substantially normal or self-similar probabilistic distribution. As will be appreciated, a lognormal distribution is a continuous distribution of a random variable whose logarithm is normally distributed. It typically resembles a positively or negatively skewed curve. The typical probability density function of a random variable X having Λ(μδ 2) is: P ⁡ ( x ) = { x ≥ 0 1 2 ⁢ πσ ⁢ ⅇ - ( x - μ ) 2 / 2 ⁢ σ 2 x ≤ 0 where, μ is the mean δ the standard deviation and δ 2 the variance. A typical probability density function for a normal or Gaussian distribution is: P ⁡ ( x ) = { - ∞ ≤ x ≥ ∞ 1 2 ⁢ πσ ⁢ ⅇ - ( x - μ ) 2 / 2 ⁢ σ 2 where X is a random variable, μ is the mean, δ the standard deviation, and δ 2 the variance. Referring to FIG. 2 , an architecture for modeling or simulating packet interarrival times in an ATM switch is illustrated. The architecture 50 includes inputs 54 and 58 , normal number generator 62 for generating an at least substantially normally distributed set of interarrival times, lognormal number generator 66 for generating an at least substantially lognormally distributed set of interarrival times, and combiner 70 . Input 54 inputs the number of packets (in the packet stream 22 passing through the ATM switch) having normally distributed packet interarrival times and the mean and variance of the corresponding normal distribution into the normal number generator 62 . Input 58 inputs the number of packets (in the packet stream 22 passing through the ATM switch) having lognormally distributed packet interarrival times and the mean and variance of the corresponding lognormal distribution into the lognormal number generator 66 . Although any random or pseudorandom number generator that produces values having the desired probabilistic distribution can be used for the number generator, preferred random or pseudorandom generators are the MATLAB™ lognormal and normal random or pseudorandom number generator programs distributed by The MathWorks, Inc. The combiner 70 combines the outputs 74 and 78 from the generators 62 , 66 , respectively, to form a synthetic traffic stream 82 . The synthetic traffic stream 82 replicates the distribution of packet interarrival times resulting from the ATM switch 10 and the mixture of packet types in the traffic 22 entering the switch 10 . FIG. 3 is a flow schematic of an embodiment of a method for operating the architecture of FIG. 2 . In box 100 , the user must determine the traffic mixture. In a typical ATM network, the traffic 22 is characterized or defined in terms of the share or percentage of the packets in the traffic 22 entering the switch that contain voice information, that contain video information, and/or that contain data (information other than voice and/or video information). With this mixture, the number of packets containing each type of information, namely voice, video, and data, can be determined by multiplying the percentages by the total number of packets passing through or routed by the switch during a selected time interval. In some applications, a volumetric range of packets in each category (voice, video, and data) will be determined. In some applications, packets (such as those containing data) will have interarrival times characterized by a bimodal distribution; that is, some of the packets will have interarrival times that are distributed normally and other of the packets will have interarrival times that are distributed lognormally. In such applications, the numbers of packets in each category must be determined. This can be done by assigning a percentage or range of percentages to the portion of the packets having normally distributed interarrival times and/or lognormally distributed interarrival times. These percentages or ranges of percentages can then be multiplied by the total number of packets passing through or routed by the switch in a specified time interval to yield the number of packets in each category (i.e., having normally or lognormally distributed interarrival times). In box 104 , the pertinent input parameters are input into the normal number generator 62 and lognormal number generator 66 . For the normal number generator 62 , the input variables are the mean and variance of the normal distribution of the data packet interarrival times (that are distributed normally) and the total number of data packets of this type passing through the switch during the selected time interval. For the lognormal number generator 66 , the input variables are the mean and variance of the lognormal distribution of the data packet interarrival times (that are distributed lognormally) and the total number of data packets of this type passing through the switch during the selected time interval. In boxes 108 and 112 , number generators each generate and output values that can be a serial stream of packet interarrival times and/or a series of sets of values, e.g., a packet interarrival time and the number of packets corresponding to the packet interarrival time. The total number of values generated by each generator is typically equivalent to the number of data packets having normally distributed interarrival times (for the normal number generator) and to the number of data packets having lognormally distributed interarrival times (for the lognormal number generator). The outputted values from each number generator are combined in a summing step 116 to form a composite traffic stream of data packet interarrival times. In box 120 , parameters are inputted into a lognormal number generator 66 (which may be the same or different from the generator 66 operated in box 108 ) in relation to the packets containing voice and/or video information. The inputted variables include the total number of packets containing voice and/or video information that are routed by the switch during the selected time interval and the mean and variance of the lognormal distribution of the voice and/or video packet interarrival times. In certain applications, the lognormal distributions of voice packets on the one hand and video packets on the other are different. In such situations, separate lognormal number generators 66 can be used to handle the differing input parameters (i.e, the differing numbers of voice and video packets, the differing means and variances of the two distributions, and the like). In box 124 , a stream of values are generated by the lognormal number generator. As noted, the values can be a serial stream of packet interarrival times and/or a series of sets of values, namely a packet interarrival time and the number of packets corresponding to the packet interarrival time. The number of values outputted by the number generator 66 is typically the same as the total number of voice and/or video packets routed by the ATM switch during the selected time interval. In box 128 , the composite traffic stream of data packet interarrival times (from box 116 ) and the stream of voice and video packet interarrival times (from box 124 ) are combined to produce a synthetic traffic stream 132 . The synthetic traffic stream 132 can be used to design the various components of the ATM network. For example, the traffic stream 132 can be used to determine the required number of buffers and/or buffer capacity, the desired transmission speed of packets, peak delay of traffic stream and optimum traffic mix (e.g., voice, video or data) of an ATM traffic channel. EXPERIMENTAL FIGS. 4A and B present actual data taken from an ATM network. The network was serviced by a Fujitsu FETEX-150™ multi-service switching platform providing ATM switching services in the network. The host ATM was implemented using self-routing modules in a multi-stage network. It provided switching functions and served as the center for call processing and operations, administration, maintenance, and provisioning. Two broadband remote switching units in the network contained the customer interfaces and performed line concentration functions. Three customer sites were connected to the ATM network in a physical star configuration via Synchronous Optical NETwork (SONET) fiber links operating at 622.08 Mb/s (OC-12 rate). Forty-one files were obtained, fifteen of which were corrupted and unusable. The data was collected during eight data collection sessions on four different days over a four month period. Busy hour sampling was performed because packet interarrival processes were non-stationary. The data files were uncompressed and processed with a statistical analysis program. The statistical analysis program provided a file with the number of data cells, data bursts, interarrival cells, and interarrival bursts in the data. The file also contained the traffic data stream itself represented as a column of integers. The traffic data stream from each file was separated into three files: (i) the complete traffic data stream, (ii) the data cell traffic stream, and (iii) the interarrival cell stream. The data files were input into MATLAB™ for analysis. The individual files within a session were analyzed individually and then concatenated and analyzed collectively. Since the results from the eighth session were representative of the entire body of data and since this was one of the larger data sets, the results from this session will be discussed below. FIGS. 4A and B are histograms of the interarrival times for this session. As can be seen from FIGS. 4A and B, the histogram appears as a mixture of two distributions: a large lognormal distribution 150 for packet interarrival times of about 0.3×10 −4 seconds or less and a much smaller normal distribution 154 for packet interarrival times exceeding about 0.3×10 −4 seconds. The much smaller normal distribution 154 caused by the switch input buffer filling up. These delayed packets form queues which are similar in length and distribution to Ethernet packets (which have normally distributed packet interarrival times). The majority of the interarrival times were very short in length, with the mean interarrival time being approximately 0.3×10 −4 seconds. Model fitting was performed to characterize the curve defining the data in FIG. 4B . The following model was developed: F(x)=Ψ·Λ(μ a .δ 2 1 ,)+(1−Ψ)·N(μ 2 ,δ 2 2 ) where the mixing parameter, Ψ, is about 0.97, μ 1 , the mean of the lognormal distribution 150 , is about −12.0156, δ 1 2 , the variance of the lognormal distribution 150 , is about 1.3850. μ 2 , the mean of the normal distribution 154 , is about 6.1293×10 −5 , and δ 2 2 the variance of the normal distribution 154 , is about 1.6464×10 −5 . Using the means and variances of the model and the sample size of FIGS. 4A and 4B , the data in FIG. 5 was generated using lognormal and normal random number generators in MATLAB™. A comparison of FIGS. 4A and 5 demonstrates the close correlation between the actual and synthetic data. Of course, a simple moment matching model will not perform well in capturing the burst pattern characteristics of the data. An algorithm which synthesizes the buffering and transmission characteristics of the sending and receiving mechanisms would produce burst patterns similar to those of real traffic. In the model, the mixture parameter, Ψ, is dependent on (i) the speed at which traffic enters and leaves the switch, (ii) the priority of the traffic, and (iii) the size of the switch input buffers. As the transmission speed and/or buffer size increases, the parameter Ψ tends to 1 and the traffic distribution tends to total lognormality. Another ATM local area network was designed and built for the purpose of investigating the architecture and management algorithms appropriate to the local area. The network architecture is a manageable network, i.e., both the network resources and resource demands made by traffic are identifiable and quantifiable. An ATM camera was set up to transmit 25 frames per second, JPEG compressed, 24 bits per pixel color video from a regular television transmission. The ATM camera transmitted cells to a network port controller which performed the traffic measurements, and from there to a Sun Sparc 10 workstation which displayed the video. The traffic trace is the first 1000000 cells of transmission, which included both action scenes (an explosion) and relatively static portions when credits were rolling on the screen. FIG. 6 is a histogram plot of the camera data. The histogram of traffic interarrival times is heavy tailed and contains a relatively small normal distribution 160 after main lognormal distributions 170 a–c . The peak in the tail 160 is around 0.225 msec, which is nearly four times the magnitude of the peak in the tail 154 of FIG. 4A (around 0.06 msec). The input buffers of the ATM switches in both requirements were 128k bytes. The higher egress speed of the architecture in the first experiment allowed the buffers to clear faster, which resulted in less cell delay and a lighter tail distribution. Model fitting was performed to characterize the curve defining the data in FIG. 6 . The following model was developed for the curve which had three lognormal distributions 170 a–c and one normal distribution 160 : F ( x )=(0.20 Ψ)·Λ(μ 1 ,δ 2 1 )+(0.20 Ψ)˜Λ 2 (μ 2 .δ 2 2 )+(0.60 Ψ)˜Λ 3 (μ 3 ,δ 2 3 )+(1−Ψ)· N (μ 4 ,δ 2 4 ) where the mixing parameter, Ψ, is about 0.98, μ 1 , the mean of the first lognormal distribution 170 a , is about −11.5784, δ 1 2 , the variance of the first lognormal distribution 170 a , is about 0.5194, μ 2 , the mean of the second lognormal distribution 170 b , is about −10.3165, δ 2 2 , the variance of the second lognormal distribution 170 b , is about 0.1997, μ 3 , the mean of the third lognormal distribution 170 c , is about −9.3908, δ 3 2 , the variance of the third lognormal distribution 170 c , is about 0.3095, μ 4 , the mean of the normal distribution 160 , is about 2.2546×10 −4 , and δ 4 2 , the variance of the normal distribution 160 , is about 2.1980×10 −5 . The first and second lognormal distributions 170 a and b were each deemed to be 20% of the total lognormal distribution 170 a–c , and the third lognormal distribution 170 c was deemed to be 60% of the total lognormal distribution 170 a–c. FIG. 7 is a histogram generated with the MATLAB™ lognormal and normal random number generators using the means and variances in the model and the sample size in FIG. 6 . As in the case of FIGS. 4A and B and 5 , the computer generated data in FIG. 7 closely correlates with the actual data in FIG. 6 . The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. By way of example, the architecture of FIG. 2 could have a number of lognormal and/or normal random number generators operating in parallel on differing portions of the packet stream. This may be the case for data, voice, and video packets or different lognormal distributions within a packet type or among packet types such as those in FIG. 6 . Alternatively, the lognormally distributed interarrival times for voice, video and data packets can be replicated using a single lognormal random number generator. The embodiments described herein above are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

The present invention is directed to a traffic simulation algorithm for an asynchronous transfer mode communications (ATM) network. The algorithm recognizes that packets in ATM networks can have interarrival times that are lognormally distributed or lognormally and normally distributed. Lognormal and, in some cases, normal random number generators are used to generate packet interarrival times of a synthetic traffic stream.

This invention was made with support under contract N00014-90-C-2060 awarded by the Naval Research Laboratory. The United States Government has certain rights in this invention. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved electron gun, and more particularly, to an advanced center post (ACP) gun for producing a hollow electron beam having either a small orbit or a large orbit. 2. Description of Related Art It is well known in the art to utilize a linear beam device within a traveling wave tube (TWT), klystron, magnetron or other microwave device. In a linear beam device, an electron beam originating from an electron gun is caused to propagate through a tunnel or a drift tube generally containing an RF interaction structure. At the end of its travel, the electron beam is deposited within a collector or beam dump which effectively captures the spent electron beam. The beam is generally focused by magnetic or electrostatic fields in the interaction structure of the device in order for it to be effectively transported from the electron gun to the collector without loss to the interaction structure. An RF wave can be made to propagate through cavities within the interaction structure and interact with the electron beam which gives up energy to the propagating wave. Thus, the microwave device may be used an amplifier for increasing the power of a microwave signal. The electron gun which forms the electron beam typically comprises a cathode and an anode. The cathode includes an internal heater which raises the temperature of the cathode surface to a level sufficient for thermionic electron emission to occur. When the potential of the anode is positive with respect to the cathode, electrons are drawn from the cathode surface and moved towards the anode. The geometry of the cathode and anode provide an electrostatic field shape which defines the electron flow pattern. The electronic flow then passes from the electron gun structure to the interaction region of the microwave device. An electron gun of this type is known as a Pierce gun. In one particular type of Pierce gun, a hollow electron beam is formed. By varying the axial magnetic field, the electrons in the hollow beam can be made to orbit some of the magnetic flux lines. As the magnetic field is increased, a significant fraction of the axial energy of the electron beam is converted to motion transverse to the beam axis. This gyrating beam is used in several microwave devices which convert the transverse energy of the beam into RF energy. Examples of these devices are the peniotron, gyrotron, gyroBWO, gyroTWT, etc. A prior art gyrotron is shown in FIG. 1. The cathode of a hollow beam gun is generally annular so that it emits a circular beam of electrons 18, as shown in FIG. 2a. The hollow beam can be characterized as either a large orbit beam in which the electrons 44 spiral about a guiding center of the beam near the axis of the microwave device in a circular path 42, or a small orbit beam in which the electrons orbit around individual flux lines of the guiding magnetic field in the interaction region. The rotation of the electrons in a large orbit beam is induced by a magnetic field reversal at the front end of the interaction region. The large and small orbit beams are shown graphically at FIGS. 2a and 3, respectively. One class of devices utilize large orbit beams for production of a microwave output through a process known as cyclotron resonance maser (CRM) interaction. Maser is an acronym for microwave amplification using stimulated emission of radiation. CRM interaction devices extract rotational energy from the beam in radial cavities disposed within the interaction region. The electrons 44 orbit about the guiding center at a rate known as the cyclotron frequency Ω c . The space charge forces within the gyrating electron beam result in azimuthal bunching 46 of the orbiting electrons, shown graphically in FIG. 2b. If the frequency of the propagating RF wave is slightly greater than the cyclotron frequency, the electron bunches fall back into a decelerating field and transfer their energy to that field. Interaction can also take place at harmonics of the cyclotron frequency. In this case, multiple bunches are formed equally spaced about the cyclotron orbit. Both the efficiency and stability of CRM devices and peniotrons are strongly dependant on the ratio of transverse velocity to axial velocity of the beam, known as α. In these devices, the α value is usually between 1 and 2. Increasing αwill raise the efficiency of these devices until the device becomes unstable. In order to obtain maximum efficiency of energy transfer to the RF wave, uniform transverse and axial velocity of the orbiting electrons is desired. In practice, such velocity uniformity is difficult to achieve. A standard magnetron injection gun (MIG) has a conical cathode which produces a small orbit beam that is constrained to move axially by the applied magnetic field. In the standard MIG gun, magnetic flux threads the cathode in order to control the beam radius and improve beam stability. However, this type of MIG gun is impractical for producing a large orbit beam since the variation in flux across the cathode surface translates to variation in angular velocity after the magnetic field reversal. Other electron gun designs utilize a shielded cathode with a center post to reduce or eliminate the magnetic field at the cathode and decreases the transverse velocity spread. However, the beam radius of these guns is typically limited to the cathode radius, and can not be readily adjusted to accommodate very short wavelength RF signals, such as in the millimeter wavelength range. Thus, these shielded cathode designs have not been successfully applied in forming large orbit axis encircled beams in these applications. SUMMARY OF THE INVENTION Accordingly, a principal object of this invention is to provide an electron gun capable of producing a hollow electron beam which can form either a large electron orbit or a small electron orbit. An additional object of this invention is to provide an advanced center post electron gun which produces an axis encircling electron beam for CRM interaction wherein the beam has reduced axial and transverse velocity variation over that of a conventional axis encircling beam. Yet another object of this invention is to provide an electron gun which produces an axis encircling large orbit beam in which the beam radius α and rotational frequency can be independently varied. In accomplishing these and other objects, there is provided an electron gun having an annular shaped cathode, a control electrode adjacent the cathode, and an annular anode disposed a fixed distance from the cathode and having an opening therethrough. A center post is disposed axially within a center region of the cathode and the control electrode along a center line of the electron gun and interaction region of a microwave device. The anode is shaped in conjunction with the center post to control position of equipotential lines of an electric field provided in an inter-electrode space between the cathode and the anode so that an electron beam emitted by the cathode converges at the opening in the anode. The control electrode provides electrostatic focusing of the beam to further control the beam convergence. In particular, the control electrode further comprises an inner and an outer beam control electrode spaced a fixed distance from the cathode. A bias voltage is provided between the outer and inner beam control electrodes, to deflect the electron beam relative to the center line and to determine the convergence point of the beam. In one embodiment of the invention, a magnetic field reversal is applied after the convergence point of the electron beam. A triple polepiece structure is provided to perform the magnetic field reversal. The polepieces have tapered ends which minimize the axial length in which there is an absence of magnetic field. Once it passes the field reversal point, a portion of the axial velocity of the electron beam is converted to angular velocity, resulting in a rotation of the beam at the cyclotron frequency ω c . The guiding center for this rotation is at or near the beam axis. In an additional embodiment of the invention, the center post has a liquid cooled core. Spiralling coolant channels extend axially through the center post beneath the outer surface of the center post. A coolant exhaust channel extends through the center of the center post. A coolant fluid entering the center post flows through the radial coolant channels, and then is exhausted through the central channel. The coolant maintains the center post at a constant temperature, which prevents deformation of the center post surface. A more complete understanding of the electron gun of the present invention will be afforded to those skilled in the art as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will be first described briefly. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic side view of a prior art hollow beam gyrotron having a cathode assembly, an interaction area, and a collector; FIG. 2a is a sectional view of a gyrating electron beam; FIG. 2b is a view as in FIG. 2a showing azimuthal electron bunching due to a transverse electric field; FIG. 3 shows a normal small orbit gyrotron beam; FIG. 4 is a side sectional view of a gyrotron electron gun of the present invention; FIG. 5 is an enlarged side view of the electron gun showing the equipotential lines between the cathode and anode; FIG. 6a shows a prior art triple polepiece magnetic field reversal configuration; FIG. 6b is a graph showing the reversal of magnetic flux density through the triple polepiece of FIG. 6a; FIG. 6c is a graph showing the behavior of an electron beam passing through the field reversal element of FIG. 6a; FIG. 7 is a detailed side view of a preferred embodiment of the gyrotron electron gun of the present invention; and FIG. 8 is an enlarged side view as in FIG. 7. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention represents a significant improvement over the prior art gyrotron electron guns, in that it permits a single gun to produce either a small orbit or a large orbit electron beam. Moreover, a large orbit beam produced with this gyrotron gun experiences dramatically reduced axial and transverse velocity spreads over the prior art devices, which significantly increases the efficiency of CRM interaction. Referring first to FIG. 1, a diagram of a prior art gyrotron assembly 10 is shown. An electron gun assembly 12 has a thermionic emitting cathode 14 with an emitting surface 16 that emits a circular electron beam 18. The beam 18 passes from the electron gun assembly 12 into an interaction structure 20 through a centrally disposed interaction region 25 of the structure. A magnetic field reversal occurs at an initial portion 26 of the interaction structure 20, which imparts an angular velocity on the electron beam, resulting in the beam spiraling as shown at 22. An RF signal is introduced into the interaction structure 20 through one or more couplers 24. The RF signal interacts with the spiraling beam and energy from the beam transfers to the moving wave. At the end of the interaction structure 20, the spent electron beam exits the interaction structure through the second aperture 28 and is gathered in the collector 30. Before exiting the interaction structure 20, the spiraling beam 22 passes a second magnetic field reversal, which linearizes the beam. The now linear beam enters the collector 30 and is rapidly decelerated by numerous stages of depression electrodes 32. Each of the stages of depression electrodes 32 have increasingly negative voltages applied to rapidly decelerate the electrons of the linearized beam, so that only a small portion of the electrons reach the back wall 34 of the collector 30. By dispersing the electrons in this manner, the electrons do not focus on any one individual point in the collector, which would generate excess heat that can overstress or cause damage to the collector structure. In the absence of the first field reversal, the individual electrons of the beam 18 would produce the small orbit beam 48 shown in FIG. 3. Rather than gyrating about the centerline of the beam, the individual electrons would gyrate around the magnetic field lines within the interaction region 25. The radius of the orbit path around the magnetic field lines is known as the Larmor radius of the beam. In a small orbit beam, the Larmor radius is relatively small relative to the guiding center of the beam. However, in a large orbit beam the Larmor radius is roughly equivalent to the radius relative to the guiding center of the beam. Referring now to FIGS. 4 and 5 there is shown an electron gun 50 of the present invention. The gun has an outer support structure 51 and a backwall 55. The structure 51 is generally cylindrical in shape, as are a majority of the components of the electron gun. Due to this cylindrical geometry, the side view of FIG. 4 shows the symmetry of the gun. Thus, it should be apparent that like elements from the upper and lower portions of the figure are counterparts of the same component. An internal cylindrical structure 57 supports the gun assembly as will be described below. Insulating support cylinders 52 and 53 are disposed concentric within the outer structure 51 and inner cylinder 57. The support cylinders 52 and 53 electrically insulate the various components of the gun and provide structural support for the cathode components. A cathode support ring 54 is secured to an end of the insulating support cylinder 53. The support ring 54 and support cylinder 53 can be secured together by brazing or other known joining technique. The support ring 54 is annular in shape and extends inwardly relative to the support cylinder 53. A cathode assembly 56 is secured to an inner diameter portion of the cathode support ring 54. The cathode assembly 56 has an inner core 58 with a heater filament 62 disposed below an external emitting surface 64. The emitting surface 64 has a generally concave annular shape. A highly negative voltage of approximately -5 kilovolts is applied to the cathode emitting surface 64. The internal heater filament 62 increases the temperature of the surface to produce thermionic emission of electrons from the surface. At an outside diameter and inside diameter of the emitting surface 64, outer and inner focus electrodes 65 and 66 are disposed, respectively. The focus electrodes 65 and 66 are electrically connected to the emitting surface 64, and contribute to shaping the electric field as will be further described below. In the preferred embodiment, the focus electrodes 65 and 66 form a 62.5° angle with the emitting surface 64. The focus electrodes 65 and 66 ensure that the electron beam remains uniform as it exits the cathode. Adjacent to the cathode emitting surface 64, outer and inner beam control electrodes 67 and 68 are provided. The inner beam control electrode 68 extends from a support cylinder 74 having a lower flange which mounts to an insulator ring 76 secured to a rear portion of the cathode assembly 56. The outer beam control electrode 67 extends from a support cone 72 which attaches to the insulating support cylinders 52 and 53. The support cone 72 has an annular ring portion 73 which is sandwiched between the support cylinders 52 and 53. The ring portion 73 secures to the support cylinders 52 and 53 by known joining technique, such as by brazing. A bias voltage of approximately 100 volts may be applied between the inner and outer beam control electrodes 67 and 68, as will be further described below. An anode 80 is disposed a fixed distance from the cathode and the beam control electrodes 67 and 68. The anode 80 has an external surface 82 having a generally angled portion which contributes to shaping the electric field. The angle formed between the anode surface 82 and the cathode emitting surface 64 is roughly equal to the angle formed between the emitting surface and the center post 84. The anode 80 is maintained at ground potential, and thus is highly positive with respect to the cathode. Typically, the anode 80 is made of copper material. The center post 84 is disposed along a centerline of the electron gun 50, and is concentric with the cathode assembly 56. The center post 84 has a rounded cap 86 which extends into the first aperture 26 leading to the interaction region 100. The center post 84 is rigidly secured to the back wall 55 of the electron gun by a support cone 94. It is critical that the center post 84 be as stiff as possible, since any deformation of the center post would alter the electric and magnetic fields and consequently the electron beam. With the negative voltage applied to the cathode, an electric field is formed between the cathode surface 64, the anode 80, and the center post 84. Since the cathode surface 64 is highly negative with respect to the anode 80 and center post 84, a beam of electrons 18 are drawn from the emitting surface 64. The electron beam 18 and the equipotential lines 124 of the electric field are shown graphically in FIG. 5. The equipotential lines 124 fall along the outer surface of the center post 84. Since the center post 84 carries the magnetic flux enclosed by the beam, no magnetic field variation occurs across the cathode surface. The cathode 56 and control electrodes 67 and 68 are enclosed within the iron cylinder 57 and backwall 55 such that the cathode region is magnetic field free. All the magnetic flux that would normally be present within the cathode diameter is carried by the center post 84. The electron beam 18 follows a path which is generally perpendicular to the equipotential lines. Thus, it should be apparent that the direction of the beam can be controlled by selecting the angle of the anode surface 82 relative to the position of the center post 84 to control the shape of the equipotential lines. A beam control voltage is provided between the cathode surface 64 and the beam control electrodes 67 and 68. This beam control voltage is up to 4,000 volts, and provides electrostatic focusing of the beam 18. The shape of the beam control electrodes 67 and 68 produces a compound electrostatic lens which causes beam divergence 120 at the entrance of the lens and beam convergence at the exit 70. This has the effect of increasing the annular width of the beam and extends the "throw" of the beam. The throw of the beam is the distance from the cathode emitting surface 64 to the plane where the annular width of the beam is at its minimum value. This minimum annular width plane is positioned at the center of the magnetic field reversal described below, in order to achieve minimum velocity spread in the beam. The electrostatic lens effect is shown graphically in FIG. 5. Between the inner and outer beam control electrodes 67 and 68, a small bias voltage is applied to deflect the beam trajectories slightly in order to optimize the entrance angle into the magnetic field reversal. This voltage is nominally less than one percent of the cathode to anode voltage. Thus, varying the shape, control voltage and bias voltage of the beam control electrodes 67 and 68 each contributes to altering the orbit radius of the beam, and its velocity and guiding center spread. Once the circular beam reaches the interaction region 100, it remains focused at the minimum orbit radius by the magnetic field disposed within the interaction region. The individual electrons of the beam would tend to gyrate around the magnetic field lines, producing a small orbit beam. However, if it is desired to produce a large orbit beam, a larger portion of the electron's axial velocity must be converted to a transverse or angular velocity. To accomplish this, a magnetic field reversal is provided. As known in the art, a magnetic field reversal would impart an azimuthal force on the moving electrons. The field reversal can be accomplished by simply reversing the polarity of the magnetic field B o within the interaction region forming a boundary in which the field changes from +B o to -B o . However, it has been found that an abrupt change in field causes ripples or scalloping of the beam downstream from the field reversal point. The scalloping causes inefficient CRM interaction and should be avoided. To minimize this scalloping, a triple polepiece magnetic field reversal element is applied. An example of a triple polepiece element is shown in FIG. 6a. The element comprises outer polepieces 132 and 133, a first inner polepiece 134, a second inner polepiece 136, and a third inner polepiece 138. Outer magnets 142 and 143 are provided between the outer polepiece 132 and first inner polepiece 134, and the outer polepiece 133 and third polepiece 138, respectively. Inner magnets 144 and 145 are disposed between the first and second inner polepieces 134 and 136 and the second and third inner polepieces 136 and 138, respectively. As shown in FIG. 6a, the polarity of the outer magnet 142 and inner magnet 144, are equivalent, as are the outer magnet 143 and inner magnet 145. These magnets can be either permanent magnets or solenoid coils. The arrangement results in the change in magnetic flux density Z shown in FIG. 6b. There is an abrupt change in the magnetic field, from +B o to -B o , during which there is a point of zero magnetic flux Z o . FIG. 6c shows the behavior of the electron beam 18 passing through the reversal point at Z o . At the first portion of the beam, the beam rotation Θ is equal to zero. After the field reversal, the rotation of the beam Θ is equal to the cyclotron frequency ω c . The triple polepiece magnetic field reversal is applied in the present invention to initiate gyration of the hollow electron beam 18. To further minimize the scalloping of the beam, and to produce a more uniform axial and transverse velocity, the polepieces are tapered to minimize the axial length of the zero magnetic field region. Referring to FIG. 4, a first polepiece 102 is disposed at the beginning of the interaction region 100 and has the anode 80 secured thereto. A first magnet 104 is disposed adjacent the first polepiece 102 and adjoins a second polepiece 106. Similarly, a second magnet 112 is disposed alongside the second polepiece 106 and a third polepiece 114. Both the second and third polepieces 106 and 114 have tapered surfaces 108 and 116, respectively. The tapered surfaces 108 and 116 are generally convergent, and result in end points 110 and 118, respectively. It has been found that these tapered polepieces effectively reduce the axial length of the zero magnetic field region, and further minimize deformation of the gyrating beam 18 after the field reversal point. The preferred embodiment of an advanced center post gun 150 of the present invention which takes advantage of the inventive concepts discussed above, is shown in FIGS. 7 and 8. The gun has an outer support structure 151 and a back wall 155. An insulating support cylinder 152 is disposed concentric within the outer structure 151 and provides structural support to the cathode assembly 156. The cathode assembly 156 has a heater filament 162 disposed below the emitting surface 164. The emitting surface 164 has a generally annular conic shape. Outer and inner focus electrodes 165 and 166, respectively, are disposed adjacent the emitting surface 164. Outer and inner beam control electrodes 167 and 168 are provided adjacent the cathode emitting surface 164. The outer and inner beam control electrodes 167 and 168 are physically supported by the insulating support cylinder 152. To provide electrical connection to the cathode emitting surface 164, the heater filament 162, and the inner and outer control electrodes 167 and 168, a plurality of electrical feedthroughs 170 1 and 170 2 are provided. Each feedthrough is formed of an electrically insulative and thermally conductive material, such as ceramic. The feedthroughs 170 have a central conductive core 172 which provides electrical conduction from outside the gun 150 to within the gun. The internal portion of the feedthrough has a plurality of thermally radiating fins 174. An extension rod 176 carrying a wire 178 extends from the core 172 to a depth equivalent with the component to which the electrical connection is desired. In FIG. 7, a first feedthrough 170 1 is shown providing an electrical connection to the cathode heater 162, and a second feedthrough 170 2 is shown providing a connection to the inner control electrode 167. Although not shown in the figure, it should be understood that a third feedthrough provides an electrical connection to the cathode emitting surface 164, and a fourth feedthrough provides an electrical connection to the outer control electrode 168. An anode 180 is shown disposed adjacent to the cathode assembly 156 and control electrodes 167 and 168. As described above, an angle formed by the anode surface 182 is selected so that the electron beam roughly bisects the angle between the anode surface 182 and the center post 184. FIG. 7 shows an estimated convergence point within the interaction region 200 of the gyrotron. The triple polepiece field reversal element is also shown, with a center polepiece 206 having a tapered end 208, and an outer polepiece 214 with a tapered end 216. The tapered ends 208 and 216 converge towards each other. In the preferred embodiment, the field reversal point approximately coincides with that of the beam convergence point. Also included in FIG. 7 is an ion pump 190. As known in the art, the generation of an electron beam often results in the development of undesired ions within the gun structure 151. The ion buildup can be detrimental to the operation of the gun. Accordingly, the pump 190 removes ions from within the gun structure 151 and maintains a near vacuum environment. As described above, it is necessary to maintain the center post 184 at a near uniform temperature so as to avoid deformation of the center post surface. To accomplish this, a coolant fluid radiates from intake 193 into the center post 184 and through spiral channels 192 disposed below the surface of the center post as shown in FIG. 8. The coolant fluid then exhausts through center drain 188 to exhaust line 195. The center post 184 is rigidly secured to the back wall 155 by the use of a support cone 194. Having thus described a preferred embodiment of an advanced center post gun, it should now be apparent to those skilled in the art that the aforestated objects and advantages for the within system have been achieved. Although the present invention has been described in connection with the preferred embodiment, it is evident that numerous alternatives, modifications, variations, and uses will be apparent to those skilled in the art in light of the foregoing description. For example, alternative materials, joining techniques, voltages, and spacing can be selected to vary the operating characteristics of an electron gun as contemplated by the invention.

An advanced center post (ACP) gun is provided which is capable of producing either a large orbit or small orbit electron beam. The gun comprises an annular shaped cathode, a control electrode adjacent the cathode, and an annular anode having an opening therethrough. A center post is disposed axially within the center region of the cathode and the control electrode along a center line of the electron gun and interaction region of a microwave device. The anode is shaped in conjunction with the center post to control position of equipotential lines of an electric field provided in an inter-electrode space between the cathode and the anode so that an electron beam emitted by the cathode converges at the anode opening. The control electrode provides electrostatic focusing of the beam to further control the beam convergence. Multiple polepieces provide accurate control of the magnetic field in the interaction region to shape the beam and control the orbit size and velocity spread.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to drain valves and drain valve systems for use in water supply systems requiring periodic purging of the water supply systems. 2. Description of Prior Art Generally underground watering systems with drain valves that automatically drain the water from underground water supply pipes to prevent freezing and rupture of the water supply pipes are well known in the art. My U.S. Pat. No. 3,779,276 shows one such drain valve. The drain valve includes a resilient valve member which prevents water from escaping from the underground water system under high water pressures but opens as the water pressure decreases to permit the water in the underground water lines to drain into the surrounding soil. My U.S. Pat. No. 4,890,640 shows another type of drain valve having a nonextrudable sealing member. This valve is well-suited in locations where pressure surges occur in the water supply line, since the drain valve contains a valve member that is nonextrudable in relation to the discharge opening. Consequently, the drain valve continues to function normally even though high-pressure surges occur which could normally blow out other valve members. The present invention comprises an improvement over U.S. Pat. No. 3,779,276 by providing a family of drain valves which can be made to operate under different pressures by changing the internal valve member of the drain valve. One feature of the invention is a drainage system that conserves water by retaining a portion of the water in the underground water lines. A further feature of the invention is a field modifiable drain valve which can be set to operate under various field conditions. Still another feature of the invention is a water drainage system having at least two drain valves responsive to different operating pressures to accommodate the different water pressures at different locations in the watering system. BRIEF SUMMARY OF THE INVENTION Briefly, the present invention includes a drain valve modifiable for use under different water pressures by merely changing the material of valve member within the drain valve. The drain valves that respond to local water pressure conditions ensures proper functioning of the drain valve in response to the local water pressure. In addition in one embodiment the drain valves include an extended screened inlet port that project into the water supply line to prevent complete drainage of the irrigation system and thus conserve water from one watering cycle to the next. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a partial schematic view of a house with an irrigation system located around the house; FIG. 2 is a sectional view of one embodiment of my invention in the drain mode; FIG. 3 shows an sectional view of an alternate embodiment of my invention in the drain mode; FIG. 4 is a top view taken along lines 4--4 of FIG. 3; FIG. 5 is a partial sectional view of an alternate embodiment of my drain valve; FIG. 6 shows an insert from my drain valve to control the outlet drain area; FIG. 7 shows an alternate embodiment of my invention for use in large-volume water systems; FIG. 8 shows a partial cutaway view of a water conservation system; FIG. 9 shows a drain valve with an extended screened inlet port for use in a water conservation irrigation system; and FIG. 10 shows the valve member or resilient plug used in the drain valve. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 reference numeral 10 generally identifies a lawn surrounding a house 11. Connected to the water supply of house 11 is an underground irrigation system 12 having a plurality of sprinkler heads identified by reference numeral 20. The sprinkler heads are known in the art and comprise a general circular member with a plurality of holes to discharge water to the lawn area surrounding the sprinkler head. Irrigation system 12 generally comprises three different pressure regions a high-pressure region, an intermediate-pressure region and a low-pressure region. In general the water pressure in the water lines decreases as the water flows through the water lines and is diverted from the water lines to irrigate the lawn. Typically one may have a water pressure of 120 psi at the inlet to the irrigation system and only 10 to 15 psi at remote portions of the irrigation system. House 11 includes a high pressure water supply 21 which directs high pressure water to a vacuum breaker valve 22. Water from vacuum breaker valve 22 flows into primary high pressure water supply pipes 23 and 24. Water supply pipe 23 directs high pressure water to three remotely controlled electric solenoid valves 31, 32, 33 and 34. Similarly, water pipe 24 directs high pressure water to three remotely controlled electric solenoid valves 34, 35 and 36. Connected to water supply lines 23 and 24 are three high pressure drain valves identified by reference number 30H. High pressure drain valves 30H are located in a portion of the water supply line closest to the source that generally contains the highest water pressure in the irrigation system. Connected to solenoid valve 35 is a secondary water line 40 that contains a number of sprinkler heads 20 and four underground drain valves 30M. The secondary waterline contains intermediate water pressures that are generally less than the water pressure in primary water lines 23 and 24. Reference numerals 38, 39, 40, 41 and 42 identify similar secondary water lines wherein the water pressure is generally less than the water pressure in water lines 23 and 24. Connected to solenoid valve 34 is a tertiary low pressure drip irrigation system having a first pipe line 48 and a second pipe line 49. Typically drip irrigation systems contain restrictions to reduce the water pressure to permit slow irrigation of area such as shrubs or bushes around the house. While a drip irrigation system can be used to irrigate selected areas one can also use sprinkler heads that operate with low water pressures. In general, the water pressure in tertiary lines 48 and 49 is considered low relative to the water pressure in the primary and the secondary water lines. Connected to the low pressure tertiary lines 48 and 49 are three low pressure drain valves 30L that permits one to drain water from the low-pressure underground lines 38 and 49. The irrigation system shown in FIG. 1 comprises three zones of different water pressure: a primary high pressure zone proximate to the water supply, a secondary intermediate-pressure zone extending outward from the primary high pressure zone and a third low-pressure zone. The pressure in each zone is an inherent function of the line loses as water flows through the lines as well as an effect of continually diverting water from the water lines. Also if the irrigation system is located on a hill the variation in the location of the water lines can produce pressure differences in the water lines. One of the difficulties with complicated underground watering systems is that if the variation in water pressure within the water lines is extreme one set of drain valves may not properly work with the underground water system. For example, the water line pressure in the underground water line systems 23 and 24 may be 120 psi, the water line pressure in the secondary lines may be 60 psi, and the water pressure in the tertiary lines may have water pressure of 10 to 15 psi. To have an underground water system that closes the drain valves as the water pressure increases and opens the drain valves as the water pressure decreases one should match the drain valve operating pressures to the local water pressures in the underground water system. The present invention provides drain valves for use in each of the three or more pressure zones of the irrigation system of FIG. 1. FIG. 2 illustrates a preferred embodiment of drain valve 30 that operates under different line pressures. Drain valve 30 includes a housing 61 having a drain pad 62 located beneath housing 61. Drain pad 62 disperses water from the water line to the surrounding subsoil. Located in the upper portion of housing 61 is a resilient plug 64 forming a resilient two-way valve member which has a top conical portion 69 that seals against an annular seat 63a on one end of top member 63. Located on the opposite end of member 64 is a lower sealing surface 64a that seals against a seat 70 having a plurality of discharge openings 65 located therein. Resilient plug 64 is shown in greater detail in FIG. 10. Resilient plug 64 includes resilient nipples 52, neck 60, and retaining end 64b which has an end surface 64a that abuts against support surface 70, resilient plug 64 and the resilient nipples 52 are known in the art and do not constitute a novel part of this invention. Other types of resilient plugs or valve members suitable for use in my invention are shown in U.S. Pat. No. 4,890,640. Extending from surface 70 and into region 66 are a plurality of drain openings 65 which permit water to flow around member 64 when it is in the relaxed condition as shown in FIG. 2. In general, member 64 comprises a resilient material such as rubber, flexible PVC or santoprene or the like. The inherent resiliency of the material forming member 64 permits member 64 to move in response to the water pressure in the drain valve. That is, under high-water pressure at the inlet 63b, member 64 seals the drain openings 65 thereby preventing water from draining into the soil surrounding drain valve 30. When the pressure is removed from the water line, the resiliency of member 64 causes member 64 to move upward to the position shown and allow water to drain around member 64 and into the subsoil surrounding drain pad 62. In the preferred embodiment member 64 is made of a material that is about the same spedific gravity as the fluid being directed through valve 30. If member 64 floats then any fluid attempting to flow back into the water lines will be sealed off from the drain lines by member 64 seating and sealing against upper seat 63a. One feature of the present invention is the creation of a family of drain valves that can open and close under different water pressures to permit the irrigation installer to match the operating pressures of the drain valve to the local pressures in the water lines. For example, adding additional sprinklers in a specific zone can create a different operating pressure in that zone. By matching the operating pressures of the drain valve to the local water pressures the installer insures that the system operates properly. For example, in a typical system that has an extended irrigation system the pressure at the end of the water line may never get above 10 psi. If the water pressure never gets above 10 psi one should have a drain valve that closes at less than 10 psi. Yet the primary pressure zone of the irrigation systems may require a drain valve that closes at 40 psi. Obviously, a drain valve that closes at 40 psi would not be useable in the portion of the system where the pressure does not exceed 10 psi. In order to have the drain valves close as the water begins to flow through the pipes the drain valves in the secondary and tertiary zones should have drain valves that are more sensitive to lower closing pressures. A method for installing drain valves in an irrigation system having zones of high and low pressure includes the step of determining the primary high pressure region and the secondary low pressure region of the irrigation system. A user then attaches a drain valve responsive to high pressure to the high pressure region of the irrigation system. In order to permit the installer to readily identify where the drain valve is to be located a visual indication such as a colored drain valve housing allow an installer to quickly identify that the drain valve should be located in said high pressure region. The user then attaches a different drain valve responsive to low pressure to the low pressure region of the irrigation system. In order to permit the installer to readily identify where the low pressure drain valve is to be located a visual indication such as a different colored drain valve housing allow an installer to quickly identify that the drain valve should be located in the low pressure region. While only two pressure regions are described it is apparent that if desired one can break the irrigation pressure zones into multiple zones of different pressures and use multiple drain valves. For example, four differently colored drain valves each responsive to five different pressures can be used in an irrigation system. One may use an orange drain valve for the main high pressure line, a green drain valve for a lower pressure lateral line, a yellow drain valve for placing next to solenoid valves of the irrigation system, and a blue valve to place under sprinkler heads in the irrigation. With the drains continuing visual indicators such as colored housing it permits the installer to quickly install the drains in their proper location. The present invention provides for modification of known drain valves to create a family of identical appearing drain valves that are only distinguishable by visual indicators incorporated into the drain valve. That is, drain valves 30 substantially identical except for resilient plug or member 64. I have found that I can create a family of drain valves for use through the watering system by only changing the durometer of member 64. By changing the durometer or the hardness of member 64 I have been able to create a family of drain valves to operate under different pressures. The below-listed table indicates the average operating pressures and average durometers of resilient plug 64 for identical drain valve housings. ______________________________________ OPENINGVALVE CLOSING PRESSURES PRESSURESDURO- 70% 90% 100% 10% 100%METER CLOSED CLOSED CLOSED OPEN OPEN______________________________________40 3 psi 5.5 psi 5 psi 3 psi50 6.5 psi 10 psi 11 psi 10 psi 4.75 psi60 8 psi 11 psi 16 psi 14.5 psi 6 psi70 9 psi 20 psi 15 psi 7 psi80 17 psi 40 psi 30 psi 11 psi______________________________________ The table shows that if drain valve 30 is fitted with a sealing member 64 having a durometer of 40 the drain valve is approximately 90 percent closed at about 3 psi and is 100 percent closed at about 5.5 psi. When the same drain valve 30 is fitted with a sealing member having a durometer of approximately 80 the drain valves is approximately 70 percent closed at 17 psi and is 100 percent closed at 40 psi. Consequently, the changing of the durometer of sealing member 64 changes the operable range of closing pressure of the drain valve. In addition to changing the closing pressure, the pressures at which the valve opens to drain water into the surrounding subsoil also changes with a change in the durometer of sealing member 64. Note if drain valve 30 had a two way sealing member 64 with a durometer of 40 the drain valve starts to open when the pressure decreases to approximately 5 psi and is fully open when the pressure is less than approximately 3 psi. Similarly, when drain valve 30 has a sealing member of a durometer of approximately 80, the drain valve begins to open as the pressure decreases to approximately 30 psi and is fully open when the pressure decreases to approximately 11 psi. The above table showing opening and closing pressures are approximate average values of pressures and are provided as guidance to show the relative difference of operating pressures one can produce a family of valves by only changing the durometer of the resilient sealing member 64. Consequently, one can use the identical housing for each drain valve and install the proper sealing member 64 to produce a drain valve that operates properly in the normal pressure ranges. Referring to FIG. 3 reference numeral 70 shows an alternate embodiment of a drain valve that is similar to drain valve 30, except instead of having a drain pad, it includes a lower housing 71 with threads 72 for attachment to a sump line. Since use of drain valve 70 with a sump may now require the drain valve to prevent backflow drain valve 70 contains a one-way valve that does not prevent back flow. FIG. 4 shows a top view of drain valve 70, showing drain opening 65 spaced in top member 78. Illustrated by dotted lines is the normal position of the exterior cylindrical portion of sealing member 64. Reference numeral 79 indicates the cylindrical side wall of the drain valve that confines member 64 from lateral movement. Note, in any lateral position of valve member 64 the exterior cylindrical surface of member 64 are over drain openings 65. That is drain holes 65 are spaced sufficiently inward from the exterior so that a portion of resilient valve member 64 always covers the openings regardless of the lateral position of valve member 64. FIG. 5 shows an alternate embodiment of the invention which includes a valve housing 90 having a resilient sealing member 64 therein. Housing 90 has a member 91 extending across valve housing 90 with an opening 92 having an insert 93 fitted therein. The purpose of insert 93 is to reduce the diameter of the drain passage of an existing drain valve. Insert 93 is shown in greater detail in FIG. 6 and comprises a first cylindrical section 94 and a second cylindrical head section 95. Extending completely through both cylindrical head sections is an opening 92. Insert 93 permits a user to adjust the size of the drain holes in the valve by merely inserting one or more inserts into the drain valve. That is, member 93 may be made from a polymer plastic and can be fastened into an opening 92 in drain valve 90 with a solvent cement or the like. Thus an operator can adjust the size of the drain passage by merely placing an insert into the housing 90. If desired the operator can place the insert 93 in from the top to allow a field user to change the drain passage area. Referring to FIG. 7 reference number 100 generally identifies an alternate embodiment of my drain valves for use in areas where large volumes of water may be drained or discharged from a water line. Drain valve 100 includes a drain pad 101, a housing 102, a lower multiple seat 103, having a plurality of drain passage openings 104, 105, 106 and 107. Located directly above opening 104 is a first resilient valve member 110. Located directly above opening 105 is a second resilient valve member 111, located above opening 106 is a third valve member 112 and located above opening 107 is a fourth valve member 113. Extending across the top of housing 102 is a top seat 120 which has a set of openings 121, 122, 123 and 124. The resilient valve members 110, 111, 112 and 113 are identical in size and shape and operate in the same manner as the resilient valve member of FIG. 2. However, instead of having only one resilient member in the housing, the present invention has multiple resilient valve members. A feature of the embodiment shown in FIG. 7 is that the valve can be made tuned more precisely for high and low pressure openings and closings where large volumes of water are discharged. For example, if one wants a drain valve to begin closing at a low pressure so the water pressure can begin to build up in the system one or more of the resilient valve members can be made of sufficient durometer to open and close with pressures as low as 3 to 5 psi while the remaining resilient valve members can be made of different material that allows the valve 100 close at pressures of 17 to 40 psi. Consequently, by using resilient valve members of different hardness one can produce a sequencing effect where drain passages continue to close as the pressure increases or the drain passages begin to open as the pressure decreases. FIGS. 8 and 9 show an alternate embodiment of my system for conservation of water in the drain lines. One of the problems with irrigation, particularly in climates with limited water supplies, is that the water should not be unnecessarily wasted. Since the underground water lines contain substantial amounts of water, it would be desirable if some of the water could be retained in the water lines, yet one does not want to retain sufficient water in the lines so that if freezing occurs, the underground lines rupture and break. For example a 3/4 inch irrigation system may require any where from 10 to 20 gallons of water to fill the underground water lines. If only half of the water was drained from the underground irrigation lines each time the lawn was irrigated there would be a saving of 5 to 10 gallons of water each time the irrigation system is used. The present invention provides an underground drain valve 130. Drain valve 130 is identical to drain valve 30 except drain valve 130 has an upwardly extending neck 131 with an inlet port having a series of openings 132 to permit water to enter drain valve 130. To illustrate how drain valve 130 operates to conserve water and yet prevent freezing, refer to FIG. 8. A first drain valve 130 and a second drain valve 130 are attached to opposite ends of an underground water line 141 having a spray head 142. Underground water line 141 could be a portion of any the underground lines shown in FIG. 1. The water level in the line 141 is indicated by reference numeral 143. Note that the water drains to the top surface of each drain valve inlet port 132 and remains in the underground line 141 since the water can not flow upward and through the openings 132. Thus by controlling the height H that the extension 131 extends into the underground water system, one can generally control the amount of water left in the water line. Preferably, one would leave about one-half of the water in the line using underground drain valves 130. A further feature of having a screen located over the inlet to the drain valve that is spaced sufficiently far into the water supply pipe so that the water flowing past the screen produces a cleaning action on the screen to remove particles deposited on the screen. While my drain valve is shown in use for underground watering systems my drain valve can also be used as a flush valve at the end of an underground watering system. Other applications of my drain valve are as a boat drain valve, an air compressor drain valve, an overhead fire sprinkler drain, or as a drain valve for a heating and cooling condensers.

A drain valve modifiable for use under different water pressures by merely changing the material of valve member within the drain valve. The drain valves are used in a fluid system to produce a fluid system that respond to local water pressure conditions. In one embodiment the drain valves include an extended inlet port that project into the water supply line to prevent complete drainage of the irrigation system and thus conserve water from one watering cycle to the next. Another embodiment of the drain valve includes multiple resilient members for sequence action in opening and closing of the drain valve. Still another embodiment permits a user to change the size of the drain passage by placing an insert in the drain passage of the drain valve.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND [0003] 1. Field of the Disclosure [0004] The present disclosure relates generally to the shale shaker screens used to filter solids out of drilling mud. [0005] 2. Description of Related Art [0006] When drilling a well (e.g., for oil or gas), a drill bit is attached to the end of a drill string and drills a hole through the subsurface to access the oil or gas reservoir. Drilling fluid is used during drilling operations. Drilling fluid comprises, for example, a finely ground clay base material to which various chemicals and water are added to form a viscous fluid designed to meet specific physical properties appropriate for the subsurface conditions anticipated. This drilling fluid is pumped down the hollow drill pipe, through the drill bit and returned to the surface in the annular space between the drill pipe and the well bore. [0007] The drilling fluid serves three main purposes. First, it aids in cooling the drill bit and thereby increasing its useful life. Second, the mud flushes the cuttings or “solids” from the well bore and returns them to the surface for processing by a solid control system. Third, the mud leaves a thin layer of the finely ground clay base material along the well bore walls which helps prevent caving in of the well bore wall. [0008] Although often referred to simply as “mud,” the drilling fluid is a complex composition which must be carefully engineered and tailored to each individual well and drilling operation. The drilling fluid is costly and, thus, is cleaned and reused in a closed loop system in which a solids control system and a shaker play important roles. [0009] A shaker, often referred to as a “shale shaker,” is part of a solids control system used in oil and gas drilling operations to separate the solid material (“solids”), removed from the well bore by the drilling operation, from the drilling mud. For the drilling fluid to be used and reused, it must be processed after returning from the well bore to remove the aforementioned solids and maintain its proper density, often expressed as pounds per gallon or “mud weight”, i.e., 10 lb./gal. mud or “10 lb. mud”. The first step in processing the returned drilling fluid is to pass it through a shaker. The returned drilling fluid from the flow line flows into a possum belly, a container mounted at one end of the shaker, and then flows over one or more screens. A shaker includes a support frame on which the shaker screen is mounted. One or more motors in the shaker causes the screen assemblies to vibrate or oscillate, depending on the type of motors utilized. The vibrating action of the screens over which the mud passes removes larger particle size solids (e.g., in the 200 to 700 micron size range) while allowing the drilling fluid and smaller particle size solids to pass through the screen. Solids, which are discarded from the top of the shaker screen, discharge into a pit or onto a conveyor for further treatment or disposal and the underflow drilling fluid flows into the tank below. [0010] A common means to secure the screen in the shaker is through the use of a wedge block. A wedge block is typically inserted between the screen and a bracket located along the inside walls of the shaker. The wedge block is pushed further back under or into the bracket, in turn pushing the wedge downward onto the screen and onto the shaker. Two wedges are typically used per screen, but other combinations of wedges may be utilized. [0011] A common means to seal the screen in the shaker is through the use of gaskets secured to the shaker at the screen interface. The gasket is typically secured to the shaker with various fasteners that wear out due to contact with the drilling fluid and solids. Thus, maintenance is required to replace worn gaskets and/or fasteners. Replacing the gaskets is time- and labor-intensive—the shaker must be taken offline, the wedge blocks removed, the screens removed, the fasteners ground off, the old gasket material removed, and the new gaskets installed with new fasteners, and then the screens and wedge blocks reinstalled. [0012] Accordingly, there remains a need in the art for a shaker screen and sealing gasket capable of easy and efficient replacement, while retaining the necessary securing and sealing properties within a shaker device. SUMMARY OF THE PRESENT DISCLOSURE [0013] The embodiments described herein are generally directed to a means for securing and sealing a shaker screen in a shaker device. [0014] In an embodiment, an assembly for securing and sealing a shaker screen in a shaker device comprises a shaker screen with tapered side members on which an elastomeric or plyable gasket is adhered. The assembly also comprises a support frame with angular channels that sealingly mate with the gaskets on the side members of the screens. The assembly further comprises a central, angular, bar anchor affixed to the shaker in between each group (upper and lower) of two shaker screens; the central, angular, bar anchor comprises an angular channel on each side, each of which retains a side member of a shaker screen. In addition, the assembly comprises a wedge block retention bracket affixed to the shaker side walls above each shaker screen. Moreover, the wedge block is insertable between the wedge block retention brackets and the shaker screens, providing forces both down onto the screen side member and laterally onto the tapered screen side member, which further presses the screen side member with a gasket into the angular channel of the central, angular, bar anchor, creating a seal. [0015] Thus, embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments, and by referring to the accompanying drawings. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the embodiments described herein. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0016] For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein: [0017] FIG. 1 is a perspective view of an embodiment of a shaker made in accordance with the principles described herein. [0018] FIG. 2A is a top view of an embodiment of a shaker screen made in accordance with the principles described herein. [0019] FIG. 2B is a side view of the screen shown in FIG. 2A . [0020] FIG. 2C is a perspective view of a portion of the screen shown in FIG. 2B . [0021] FIG. 3A shows a lateral cross-sectional view of the screen shown in FIG. 2A . [0022] FIG. 3B illustrates a perspective view of the screen shown in FIG. 3A . [0023] FIG. 4A is a view of the front face of an embodiment of a wedge block made in accordance with the principles described herein. [0024] FIG. 4B is a side view of the wedge block shown in FIG. 4A . [0025] FIG. 4C is a perspective view of an embodiment of a wedge block installed in a shaker in accordance with the principles described herein. [0026] FIG. 5A is a perspective view of an embodiment of a shaker support frame in accordance with the principles described herein. [0027] FIG. 5B shows a lateral cross-sectional view of a portion of the support frame shown in FIG. 5A . [0028] FIG. 6A is a perspective view of an embodiment of a central, angular, bar anchor in a shaker in accordance with the principles described herein. [0029] FIG. 6B is a partial schematic view showing an embodiment of a screen being installed in a shaker in accordance with the principles described herein. [0030] FIG. 6C is a partial schematic view showing an embodiment of a screen installed in a shaker in accordance with the principles described herein. [0031] FIG. 7 is a perspective view of an embodiment of a shaker made in accordance with the principles described herein. NOTATION AND NOMENCLATURE [0032] Certain terms are used throughout the following description and claim to refer to particular system components. This document does not intend to distinguish between components that differ in name but not function. Moreover, the drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. [0033] In the following discussion and in the claims, the term “comprises” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0034] FIG. 1 depicts a shaker 500 in accordance with various embodiments. In the example of FIG. 1 , a plurality (e.g. 4) of shaker screens 100 is secured to the shaker 500 using both a central, angular, bar anchor 530 (anchor) and a wedge block 200 with a wedge block retention bracket 540 . In other embodiments, only a single screen may be used. Though all four screens 100 and both anchors 530 , 535 are visible, only one of the four wedge block retention brackets 540 and one of the four wedge blocks 200 are visible in the perspective view of FIG. 1 . It should be appreciated that there are four wedge block retention brackets 540 , each with a wedge block 200 , in the illustrative shaker 500 shown in FIG. 1 . The shaker 500 also comprises a gumbo tray 520 and a possum belly 510 . [0035] FIG. 2A illustrates a top view of a shaker screen frame 100 . In a preferred embodiment, the screen frame 100 comprises side members 105 , 110 and a plurality of cross members 115 that extend between and are secured to side members 105 . The screen frame can further comprise a plurality of mesh screens (not shown) disposed on the cross members 115 . The type and size of mesh screen (not shown) installed on the screen frame 100 can vary and does not affect the principles relied on herein; thus, shaker screen frame 100 will hereinafter be referred to simply as shaker screen 100 or screen 100 . The cross members 115 preferably comprise square tubular members typically with smaller dimensions than the side members 105 , 110 . The side members 105 , 110 are comprised of tubular members that are tapered at the sides (as will be discussed below in greater detail). Welds may be used to secure each end of side members 105 to each end of side members 110 ; welds also secure each end of the cross members 115 to the side members 105 . The tapered configuration of the side members 105 , 110 eliminates shearing weld stress on the screen 100 during shaker 500 operation. In other embodiments (not specifically illustrated) the quantity of cross members 115 may be increased or decreased from that shown in FIG. 2A . [0036] Referring now to FIGS. 2B and 2C , FIG. 2B illustrates a side view of the screen 100 shown in FIG. 2A and FIG. 2C depicts a perspective view of a portion of the screen 100 shown in FIG. 2B . In an embodiment, the screen 100 further comprises an elastomeric gasket 120 that surrounds the outermost edge 130 of all exterior sides (indicated by dashed lines in FIG. 2B ) of the screen 100 and a portion of the side members 105 , 110 . The gasket 120 can be of varying thicknesses and widths and can cover equal or non-equal portions above and below the outermost edge 130 of side members 105 , 110 . For example, the seal may be ½″ wide with a total thickness of 1/16″ and cover ¼″ above and below the outermost edge 130 . For ease of illustration of the screen 100 geometry, the gasket 120 is only depicted in FIGS. 2B and 2C ; however, the gasket 120 can be assumed to be present but not shown in the remaining illustrated embodiments of the present disclosure. [0037] As previously discussed, the side members 105 , 110 are comprised of tubular members that are tapered at the sides, rather than square as with conventional screens. Tapered sides provide the screen 100 described herein with various benefits as explained below. The geometry of the tapered side members 105 , 110 can be more easily understood when viewing the side members 105 , 110 in cross section. FIG. 3A illustrates a lateral cross-sectional view along line 125 of FIG. 2A and FIG. 3B depicts a perspective view of same. Each side member 105 further comprises a tubular member having an inner edge 140 and outer edge 130 , a central axis 150 that runs longitudinally through the center of side member 105 and a horizontal plane 155 , which intersects the central axis 150 , the inner edge 140 , and the outer edge 130 of each side member 105 . Thus, in the cross sectional view, the side members 105 appear tapered at the outermost edge 130 and innermost edge 140 . The taper angle 160 is measured from the horizontal plane 155 to an outer planar surface of side member 105 such that the apex is outer edge 130 . It can be appreciated that a similar cross section 126 , depicted in FIG. 2A , of side members 110 would yield a substantially similar cross-sectional view as that of cross section 125 . Though not shown, the elastomeric gasket 120 would surround the outermost edge 130 of all side members 105 , 110 . [0038] As shown in FIGS. 4A and 4B , wedge block 200 comprises a front face 220 , back face 221 , top end 211 , bottom end 213 , first side 230 , second side 231 , and a central axis 250 that runs longitudinally through and halfway between the first side 230 and second side 231 and halfway between the front face 220 and back face 221 . Wedge block 200 also includes a bottom end 213 made up of two planar surfaces 214 , 216 , which are tapered and intersect to form bottom edge 218 —bottom edge 218 is off center from the central axis 250 such that the bottom edge 218 is located closer to the back face 221 than to the front face 220 as can more easily be seen in FIG. 4B . Wedge block 200 is also provided with a top end 211 that is tapered from the first side 230 and second side 231 toward the central axis 250 . [0039] In an embodiment, the wedge block 200 further comprises a plurality of notches or cutouts including a notch 260 in the top end 211 such that the center of the cut out 260 aligns with the central axis 250 and the notch 260 extends from the front face 220 through the back face 221 . In different embodiments (not specifically illustrated), the cut out 260 at the top end 211 may be off center from the central axis 250 . In an embodiment, the wedge block comprises a notch 225 disposed on both the front face 220 and on the top end 211 , extending from the first side 230 through the second side 231 . Notch 225 also follows the same tapered configuration as the top end 211 , which is tapered from the first side 230 and second side 231 toward the central axis 250 . In the embodiment shown, each wedge block 200 is symmetrical along the central axis 250 , thus, allowing one wedge block 200 to be used with any screen 100 , regardless of the screen's location. [0040] Referring to FIG. 5A , an interface between screens 100 and the shaker 500 comprises a support frame 525 . The support frame 525 includes a plurality of angled support members 548 , 549 that sealingly contact the gasket 120 on side members 105 , 110 of the screen 100 . Referring now to FIG. 5B , which illustrates a lateral cross-sectional view of a portion of the support frame 525 along line 534 shown in FIG. 5A ; a partial outline of a side member 105 of screen 100 (without gasket material) is shown in a substantially installed position merely to provide context. In an embodiment, angle 533 is measured from the top surface 538 to the base 539 of support member 548 . The angle 533 of the support frame members 548 , 549 is substantially the same as the taper angle 160 of side members 105 , 110 as shown in FIG. 3A . In some embodiments, the angle 533 of the support frame members 548 , 549 may be 45 degrees, but can be a different angle in other embodiments. For example, the angle 533 of the support frame members 548 , 549 may be less than 45 degrees. In other implementations, the angle 533 of the support frame members 548 , 549 is greater than 45 degrees. [0041] The screen 100 and wedge block 200 interface with various components of the shaker device 500 , which will be discussed herein in more detail. Referring back to FIG. 1 , a shaker interface with screens 100 comprises a plurality of central, angular, bar anchors 530 , 535 (anchor)—a lower anchor 530 and an upper anchor 535 . Anchors 530 , 535 are disposed axial to the central axis 550 and substantially in the center of shaker 500 such that a screen 100 may fit between the anchor and each side wall 545 of the shaker 500 . Referring to FIG. 6A , anchor 530 further comprises angular channels 531 , 532 that are diametrically opposed to one another. In an embodiment, each angular channel 531 , 532 sealingly retains one side member 105 of each screen 100 . Though only the lower anchor 530 is visible in FIG. 6A , it should be appreciated that the upper anchor 535 , shown in FIG. 1 , comprises angular channels 536 , 537 and operates in substantially the same way as lower anchor 530 . [0042] Referring back to FIGS. 1 and 4C , a shaker interface with screens 100 comprises a plurality of wedge block retention brackets 540 , each configured to retain a wedge block 200 against a screen 100 . Each wedge block retention bracket 540 comprises an elongated substantially “L” shaped member disposed radially from the central axis 550 and attachably connected to the shaker side wall 545 above each shaker screen 100 . A wedge block 200 is insertable between the wedge block retention brackets 540 and the shaker screens 100 such that the back face 221 of the wedge block is flush against the shaker wall 545 and the bottom end 213 interfaces with the screen side member 105 . Though only one of the four wedge block retention brackets 540 and one of the four wedge blocks 200 are visible in the perspective view of FIG. 1 , it should be appreciated that there are four wedge block retention brackets 540 , each with a wedge block 200 , disposed radially from the central axis 550 on the shaker side wall 545 above each shaker screen 100 . Conventional shakers typically require the use of two wedge blocks per screen; the present disclosure uses half as many wedge blocks; thus, greatly reducing installation time. [0043] Further, in an embodiment, each wedge block 200 is symmetrical along the central axis 250 (see FIG. 4A ), thus, allowing one wedge block 200 configuration to be used with any screen 100 —the wedge block 200 is simply oriented such that the back face 221 of the wedge block 200 is always flush against the shaker wall 545 while the top end 211 interfaces with the wedge block retention bracket 540 (see FIGS. 4A and 4C ). Thus, in some embodiments, first side 230 will be inserted under a wedge block retention bracket 540 and in other embodiments, second side 231 will be inserted under a wedge block retention bracket 540 . [0044] Referring to FIG. 1 , before a shaker 500 can be used to remove solids from waste drilling fluids, shaker screens 100 must be installed in shaker 500 . Referring now to FIG. 6A , in an embodiment, a screen 100 is installed into the shaker 500 , by first placing a side member 105 into an angular channel 531 , 532 , 536 , 537 of an anchor 530 , 535 . The mesh layers (not shown) should be facing upward when the screen 100 is installed in shaker 500 . Once the side member 105 is placed in angular channel 531 , 532 , 536 , 537 (see FIG. 6B ), the screen is essentially self-seating—the screen 100 pivots along angular channel 531 , 532 , 536 , 537 and can be released to drop in place (the motion of the screen 10 generally follows arrow 600 ) because the angles 533 of the support frame angular members 548 , 549 form an inverted pyramidal shape (i.e. a funnel) configured to align with the taper angle 160 of the screen side members 105 , 110 . Once a screen 100 is seated in the support frame (see FIGS. 6C and 4C ), a wedge block 200 is inserted between the wedge block retention bracket 540 and the shaker screen 100 such that the back face 221 of the wedge block is flush against the shaker wall 545 . A hammer or other suitable tool is then used to pound the wedge block further under the wedge block retention bracket 540 . [0045] As previously described, certain embodiments disclosed herein comprise a gasket 120 fitted on the outer edge 130 of the screen 100 (see FIG. 2B ). The application of a gasket 120 on the screen 100 itself removes the need to install gasket material on the support frame of the shaker 500 with the use of bolts or screws. Further, whenever a screen 100 is replaced due to normal wear and tear of the mesh layers (not shown), a new gasket 120 is automatically installed. Thus, replacing gasket material no longer requires the grinding of bolts and screws, reducing down time of the shaker 500 . [0046] As previously described, in an embodiment, the bottom edge 218 of the wedge block 200 is tapered (see FIG. 4B ), which provides a force both downward onto the screen side member 105 , but also laterally onto the tapered screen side member 105 . This lateral force further presses the side member 105 with an elastomeric gasket 120 into the angular channel 531 , 532 , 536 , 537 of the central, angular, bar anchor 530 , 535 , forming a substantially fluid tight seal. [0047] Referring to FIG. 7 , in an embodiment, the gumbo tray 520 may be rotated up along central axis 555 and into the cavity of the possum belly 510 to allow for easier access to the upper screens 100 for installation or removal.

A shaker screen comprises a frame that has a plurality of opposing sides. The shaker screen also comprises a screen assembly attached to the frame. In addition, each side of the shaker screen comprises a tubular member having an inner edge, an outer edge, and defining a central axis. Further, a horizontal plane intersects the central axis, the outer edge, and the inner edge of each side.

REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Application Ser. No. 60/520,213, filed Nov. 14, 2003, the disclosure of which is hereby incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention relates to integrated circuit devices and methods of operating same, and more particularly to integrated circuit devices that utilize scan chains to facilitate device testing. BACKGROUND OF THE INVENTION [0003] Scan design test techniques are frequently used to facilitate testing of complicated integrated circuit devices. A variety of these techniques are disclosed in U.S. Pat. Nos. 6,453,456 and 6,490,702. In particular, FIG. 10 of the '702 patent discloses a scan chain circuit 110 that purports to solve a latch adjacency problem when testing for delay faults within an integrated circuit. This scan chain circuit 110 includes a plurality of shift register latches 30 that operate as stages within the scan chain circuit 110. One shift register latch is illustrated as including a master latch 32 a and a slave latch 34 a . The output of the slave latch 34 a is provided to a first input of a combinational logic device 122. This combinational logic device 122 is illustrated as a two-input AND gate. The output of the slave latch 34 a is also provided to a first input of a multiplexer 112 a , which is responsive to a select signal SEL. A second inverted input 116 of the multiplexer 112 a also receives the output of the slave latch 34 a . The output of the multiplexer 112 a is provided to an input of a next shift register latch within the scan chain circuit 110. This next shift register latch is illustrated as including a master latch 32 b and a slave latch 34 b . The output of the slave latch 34 b is provided to a second input of the combinational logic device 122. This combinational logic device 122 is illustrated as undergoing a conventional delay fault test by having one input of the device 122 switch low-to-high while the other input of the device 122 is held high. The timing of this low-to-high switching of the one input of the device 122 is synchronized with a leading edge of the next clock pulse (not shown). To facilitate this delay fault test, the second inverted input 116 of the multiplexer 112 a is selected (i.e., SEL=0) so that the output of the next shift register latch (i.e., output of the slave latch 34 b ) is held at a logic 1 level when the next clock pulse is received. [0004] Accordingly, based on the illustrated configuration of the shift register latches 30 within the scan chain circuit 110, a value of the select signal SEL can be used to control whether the multiplexers 112 a -112 c operate to pass a true or complementary version of the output of a respective slave latch 34 a -34 c to the next shift register latch within the scan chain circuit 110. Nonetheless, even if the output of the slave latch 34 a can be controlled to switch states (i.e., switch 0→1 or 1→0) in response to the clock pulse (not shown), an output of the next shift register latch within the scan chain circuit 110 (i.e., the output of the slave latch 34 b ) will nonetheless be a function of a value of the output of the preceding slave latch 34 a during the delay fault test operation. This functional dependency between the output of one shift register latch and the output of a preceding shift register latch during the fault test operation can limit the effectiveness of the scan chain circuit 110 when testing for other more complicated types of delay faults within an integrated circuit device. SUMMARY OF THE INVENTION [0005] Embodiments of the present invention include an integrated circuit device that utilizes a scan chain register to support efficient reliability testing of internal circuitry that is not readily accessible from the I/O pins of the device. This reliability testing includes the performance of, among other things, delay fault and stuck-at fault testing of elements within the internal circuitry. According to some of these embodiments, an integrated circuit device is provided with a scan chain register having a plurality of scan chain latch units therein that support a toggle mode of operation. The scan chain register is provided with serial and parallel input ports and serial and parallel output ports. Each of the plurality of scan chain latch units includes a latch element and additional circuit elements that are configured to selectively establish at least one feedback path in the respective latch unit. This feedback path can operate to pass an inversion of a signal at an output of the latch to an input of the latch when the corresponding scan chain latch unit is enabled to support the toggle mode of operation. Accordingly, if the output of the latch is set to a logic 1 level, then a toggle operation will cause the output of the latch to automatically switch to a logic 0 level and vice versa. Because of the presence of a respective feedback path within each scan chain latch unit, the toggle operation at the output of a scan chain latch unit will be independent of the value of any other output of any other scan chain latch unit within the scan chain. [0006] According to additional embodiments of the present invention, a scan chain latch unit includes a latch and a pair of multiplexers that route data through the latch unit. The latch may constitute a flip-flop device that is synchronized to a clock signal, such as a positive edge triggered D-type flip-flop. In particular, a first multiplexer is provided having first and second data inputs and a select terminal that is responsive to a toggle signal. A second multiplexer is provided having a first data input electrically coupled to an output of the first multiplexer, a second data input configured as a parallel input port of the scan chain latch unit, a select terminal responsive to a scan enable signal (SE i ) and an output electrically coupled to an input of the latch. The scan chain latch unit further includes an inverter having an input electrically coupled to a true output of the latch and an output electrically coupled to the second data input of the first multiplexer. Accordingly, through proper control of the select terminals of the first and second multiplexers, a signal generated at an output of the inverter can be passed to the input of the latch and then loaded into the latch upon performance of the toggle operation. In the event the latch includes true and complementary outputs, then the complementary output may be fed back directly to the second data input of the first multiplexer and the inverter may be eliminated. [0007] Further embodiments of the present invention include a sequential scan chain register having a serial input port, a serial output port and a plurality of parallel output ports. The sequential scan chain register is configured to generate at least a first portion of a serially scanned-in test vector at a plurality of immediately adjacent ones of the parallel output ports during a preload time interval that spans multiple consecutive cycles of a clock signal. This register is further configured to respond to a launch edge of the clock signal and an active toggle signal by toggling each and every one of the bits in the first portion of the serially scanned-in vector regardless of a value of the serially scanned-in vector. [0008] According to still further embodiments of the present invention, a scan chain latch unit is configured to support a toggle mode of operation that establishes a next output state (NS) of the scan chain latch unit as an invert of a current output state (CS) of the scan chain latch unit, while blocking data at serial and parallel inputs of the scan chain latch unit from influencing a value of the next output state. The scan chain latch unit is further configured to support a freeze mode of operation that establishes a next output state of the scan chain latch unit as equivalent to a current output state of the scan chain latch unit. This mode of operation also blocks data at the serial and parallel inputs of the scan chain latch unit from influencing a value of the next output state. In these embodiments, the scan chain latch unit may include a four input multiplexer that is responsive to a pair of select signals. The scan chain latch unit may also generate a true output state (Q) that is fed back to a first data input of the four input multiplexer and a complementary output state (QB) that is fed back to a second data input of the four input multiplexer. The four input multiplexer may include first and second totem pole arrangements of PMOS and NMOS transistors having commonly connected outputs. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1A is an electrical schematic of a scan chain latch unit according to an embodiment of the present invention. [0010] FIG. 1B is a timing diagram that illustrates operation of the scan chain latch unit of FIG. 1A . [0011] FIG. 1C is an electrical schematic of a scan enable signal SE i generator according to an embodiment of the present invention. [0012] FIG. 1D is an electrical schematic of a circuit that is configured to generate scan enable and toggle signals, which are received by the scan chain latch unit of FIG. 1A . [0013] FIG. 2A is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0014] FIG. 2B is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0015] FIG. 2C is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0016] FIG. 2D is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0017] FIG. 3A is a block diagram of a scan chain latch unit according to an embodiment of the present invention. [0018] FIG. 3B is an electrical schematic of an embodiment of the scan chain latch unit of FIG. 3A . [0019] FIG. 3C is an electrical schematic of an embodiment of the scan chain latch unit of FIG. 3A . [0020] FIG. 3D is an electrical schematic of an embodiment of the scan chain latch unit of FIG. 3A . [0021] FIG. 3E is an electrical schematic of an alternative embodiment of the scan chain latch unit of FIG. 3C . [0022] FIG. 3F is an electrical schematic of an alternative embodiment of the scan chain latch unit of FIG. 3D . [0023] FIG. 4A is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0024] FIG. 4B is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. [0025] FIG. 4C is an electrical schematic of a portion of a scan chain register according to an embodiment of the present invention. DESCRIPTION OF PREFERRED EMBODIMENTS [0026] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. The suffix B or prefix symbol “/” to a signal name may denote a complementary data or information signal or an active low control signal, for example. [0027] Referring now to FIG. 1A , a scan chain latch unit 10 according to an embodiment of the present invention is illustrated as including first and second multiplexers M 1 and M 2 , a latch L 1 and an inverter I 1 . The latch L 1 is shown as a D-type flip-flop having an input D and a “true” output Q that is fed back to an input of the inverter I 1 . The latch L 1 is synchronized to a clock signal CLK. As described more fully hereinbelow with respect to FIG. 2B , the latch L 1 may also be configured as a flip-flop having true and complementary outputs Q and QB and the inverter I 1 may be eliminated. Other types of latches may also be used. The scan chain latch unit 10 has a number of ports. These ports include a serial input port SI, a serial output port SO, a parallel input port DI and a parallel output port DO. The first multiplexer M 1 has a select terminal that is responsive to a toggle signal TOG and the second multiplexer M 2 has a select terminal that is responsive to a scan enable signal SE i . When the toggle signal TOG is set to a logic 0 level (i.e., low state) and the scan enable signal SE i is set to a logic 1 level (i.e., high state), serial input data can be passed from the serial input port SI to the input D of the latch L 1 and then transferred to the output Q of the latch L 1 in-sync with a rising edge of the clock signal CLK. Alternatively, when the scan enable signal SE i is set to a logic 0 level, parallel input data can be passed from the parallel input port DI to the input D of the latch L 1 . Finally, in preparation of a toggle operation, both the toggle signal TOG and the scan enable signal SE i can be set to logic 1 levels to thereby connect an output of the inverter I 1 to the input D of the latch L 1 . In this manner, an inversion of the output Q of the latch L 1 can be passed to the input D of the latch L 1 . Stated alternatively, setting both the toggle signal TOG and the scan enable signal SE i to logic 1 levels will operate to establish an active feedback path that passes an inversion of a signal from the output Q of the latch L 1 to the input D of the latch L 1 . Then, upon receipt of a leading “launch” edge of the clock signal CLK, the output Q of the latch will undergo a toggle operation (i.e., switch high-to-low or low-to-high). [0028] The timing diagram of FIG. 1B also illustrates operation of the scan chain latch unit 10 of FIG. 1A . In FIG. 1B , the clock signal CLK is shown as having an initial leading edge that operates to synchronize the loading of data from the serial input port SI to the serial output port SO. This leading edge is received while the toggle signal TOG is held at a logic 0 level and the scan enable signal SE i is held at a logic 1 level. These settings establish a data path that extends from the serial input port SI to the input D of the latch L 1 , via the first and second multiplexers M 1 and M 2 . After this initial loading operation, the toggle signal TOG is switched low-to-high and the scan enable pad signal SE pad is switched high-to-low in advance of the next leading edge of the clock signal CLK, which is referred to herein as the launch edge of the clock signal CLK. The timing of when the toggle signal TOG switches low-to-high is somewhat flexible because it is only necessary that the low-to-high transition of TOG occur after the serial data has been loaded (i.e., after the initial leading edge of the clock signal CLK has been received) and before the launch edge of the clock signal CLK is received. As illustrated by the scan enable signal generator 12 of FIG. 1C , which includes a latch L 2 , a NOR gate NR 1 and an inverter I 2 , switching the scan enable pad signal SE pad high-to-low in advance of the launch edge of the clock signal CLK will cause the scan enable signal SE i to switch high-to-low in-sync with the launch edge of the clock signal CLK. When this occurs, a data path between the parallel data input DI of the scan chain latch unit 10 and the data input D of the latch L 1 will be enabled. The signal generator 12 of FIG. 1C has the advantage of being responsive to the scan enable pad signal SE pad , which, as illustrated by FIG. 1B , has more relaxed timing requirements and can be more easily distributed within a chip (with the scan enable signal SE i being separated for each block within the chip). [0029] Upon receipt of the launch edge of the clock signal CLK, the true output Q of the latch L 1 will undergo a toggle operation by switching from a previously loaded high state to a low state. The toggle operation is made automatic because both the toggle signal TOG and the scan enable signal SE i are high at the moment the launch edge of the clock signal CLK is received, which means the feedback path between the output of the inverter I 1 and the input D of the latch L 1 is enabled pending receipt of the launch edge. Following this, the scan enable signal SE i switches high-to-low to thereby enable the true output Q of the latch L 1 to switch to the current value of the parallel data input DI upon receipt of the next leading edge of the clock signal CLK that follows the launch edge. After this next leading edge, the scan enable pad signal SE pad switches low-to-high and the scan enable signal SE i follows in-sync with the rising edge of the scan enable pad signal SE pad signal, as illustrated by FIG. 1C . Setting the scan enable signal SE i high while the toggle signal TOG remains low will operate to connect the serial input port SI to the data input D of the latch L 1 . The data at the serial input port SI will then be passed to the true output Q of the latch L 1 in-sync with the next leading edge of the clock signal CLK, which is shown as the final leading edge illustrated by FIG. 1B . [0030] Control of the generation of the toggle signal TOG in FIG. 1B may be independent of the scan enable pad SE pad signal in some embodiments of the present invention. In particular, separate bond pads may be provided on an integrated circuit substrate and these bond pads may be electrically coupled to separate pins of an integrated circuit package that is configured to receive the scan enable pad SE pad signal and the toggle signal TOG, respectively. However, in other embodiments, the toggle signal TOG may be generated by an alternative scan enable signal generator 12 ′, which is illustrated by FIG. 1D . In particular, the toggle signal TOG may be generated at the output of an inverter I 3 , which receives the scan enable pad signal SE pad as an input signal. Thus, in the timing diagram of FIG. 1B , the timing of the toggle signal TOG may be modified so that it is set high when the scan enable pad signal SE pad switches low and set low when the scan enable pad signal SE pad switches high. [0031] FIG. 2A illustrates a scan chain register 20 according to an embodiment of the present invention. This scan chain register 20 is illustrated as including a plurality (i.e., n+1) of the scan chain latch units 10 illustrated by FIG. 1A . These scan chain latch units are shown by the reference numerals 10 a - 10 c . The first scan chain latch unit 10 a includes first and second multiplexers M 1 a , M 2 a , a D-type latch L 1 a and an inverter I 1 a . The second scan chain latch unit 10 b includes first and second multiplexers M 1 b , M 2 b , a D-type latch L 1 b and an inverter I 1 b . The last scan chain latch unit 10 c within the scan chain register 20 includes first and second multiplexers M 1 c , M 2 c , a D-type latch L 1 c and an inverter I 1 c . The scan chain register 20 is provided with a serial input port SI, a serial output port SO, a parallel input port DI 0 -DIn and a parallel output port DO 0 -DOn. By setting the toggle signal TOG high and the scan enable signal SE i high, a toggle operation can be performed in-sync with a launch edge of the clock signal CLK. This toggle operation will cause all of the data signals at the parallel output port DO 0 -DOn to be inverted to thereby facilitate a scan test operation. Moreover, this toggle operation will not be functionally dependent on the values of any of the data signals at the parallel output port DO 0 -DOn. Accordingly, if a scanned-in test vector equivalent to DO 0 -DOn=101100 . . . 1 is loaded into the scan chain register 20 in a serial fashion (i.e., in-sync with a plurality of consecutive leading edges of the clock signal CLK), then the receipt of the launch edge of the clock signal CLK will cause each bit of this test vector to become inverted (i.e., DO 0 -DOn=010011 . . . 0). [0032] Referring now to FIG. 2B , an alternative scan chain register 20 ′ is illustrated. This scan chain register 20 ′ is similar to the scan chain register 20 of FIG. 2A , however, the scan chain latch units 10 a ′- 10 c ′ have been modified to include latches L 3 a , L 3 b and L 3 c , respectively. These latches L 3 a , L 3 b and L 3 c have true and complementary outputs Q and /Q. These complementary outputs /Q are fed back to corresponding inputs of the first multiplexers M 1 a , M 1 b and M 1 c , as illustrated. The use of complementary outputs /Q with each latch L 3 a , L 3 b and L 3 c eliminates the requirement of using inverters within the feedback paths of the scan chain latch units. The scan chain register 20 ″ of FIG. 2C is illustrated as including one (or more) conventional scan chain latch unit 14 b within the chain, which is not configured to perform a toggle operation as described herein. Thus, it is not necessary that every scan chain latch unit within a scan chain register 20 ″ be configured to perform a toggle operation as described above with respect to FIGS. 1A-1B . The scan chain register 20 ′″ of FIG. 2D is illustrated as including three different configurations of scan chain latch units. The use of different scan chain latch units supports reduction in hardware (e.g., transistor count) and optimization for each configuration of combinational logic connected to the parallel data outputs DO 0 -DOn. The scan chain latch units 10 a and 14 b are similar to those illustrated by FIG. 2 C, however, the scan chain latch unit 14 c is illustrated as being responsive to the scan enable pad signal SE pad . Based on the timing diagram of FIG. 1B , upon receipt of the launch edge of the clock signal CLK, the next state (NS) of the output of the scan chain latch unit 14 c will be equivalent to the value of the data at the parallel input port DIn. [0033] As illustrated by FIGS. 3A-3B , alternative embodiments of a scan chain latch unit 30 may be configured to support a toggle mode of operation and a freeze mode of operation. The toggle and freeze modes, which are synchronized with the clock signal CLK, may utilize a pair of feedback paths that are each selectively enabled to pass data to support a respective one of the toggle and freeze modes. Other embodiments of the scan chain latch unit 30 that do not utilize feedback paths to support the toggle and freeze modes may also be implemented. In the toggle mode of operation, the next output state (NS) of the scan chain latch unit 30 equals an opposite of the current output state (CS) of the scan chain latch unit 30 (i.e., NS=/CS, where “/” designates an inversion operation). The scan chain latch unit 30 is similar to the scan chain latch unit 10 of FIG. 1A , however, the two select signals (TOG and SE i ) in FIG. 1A have been replaced by a pair of select signals SA and SB. This pair of select signals SA and SB enables selection between as many as four modes of operation. In addition to the toggle and freeze modes, two additional modes of operation include: (i) a “scan-in” mode whereby the next state of the latch unit 30 is equivalent to the data at the serial input port (SI) of the latch unit 30 when a next leading edge of the clock signal CLK is received and (ii) a “data-in” mode whereby the next state of the latch unit 30 is equivalent to the data at the parallel data input port (DI) of the latch unit 30 when a next leading edge of the clock signal CLK is received. The four possible combinations of the select signals SA and SB are illustrated more fully by TABLE 1. With these select signals, as many as four states may be established at an output of a scan chain latch unit 30 in-sync with the clock signal CLK. TABLE 1 SA SB OUTPUT OF SCAN CHAIN LATCH UNIT 30 0 0 NS = DI; NORMAL LOGIC OPERATION 0 1 NS = Q; FREEZE MODE FOR SPEED TEST 1 0 NS = QB; TOGGLE MODE FOR SPEED TEST 1 1 NS = SI; SCAN-IN MODE FOR SCAN CHAIN SHIFTING [0034] FIG. 3B illustrates a detailed electrical schematic of one embodiment of the scan chain latch unit 30 of FIG. 3A . This electrical schematic includes two totem pole arrangements of PMOS and NMOS transistors having commonly connected outputs, which are provided as an input to a first transmission gate TG 1 . The first totem pole arrangement of transistors includes PMOS transistors P 1 -P 4 and NMOS transistors N 1 -N 4 , connected as illustrated. The second totem pole arrangement of transistors includes PMOS transistors P 5 -P 8 and NMOS transistors N 5 -N 8 . These two totem pole arrangements of transistors operate as a 4-input multiplexer that is responsive to the two select signals SA and SB. The four data inputs of the multiplexer include the serial input port (SI), the data input port (DI), a first feedback path, which electrically connects a complementary output (QB) of a latch unit to gate terminals of PMOS transistor P 3 and NMOS transistor N 3 , and a second feedback path, which electrically connects a true out (Q) of the latch unit to gate terminals of PMOS transistor P 7 and NMOS transistor N 7 . Inverters I 2 and I 3 are also provided for inverting the select signals SA and SB. The latch unit is illustrated as including a first latch, which is synchronized with a clock signal CLK, and a second latch connected to an output of the first latch. This first latch includes a first pair of inverters connected in antiparallel (L 4 ), first and second transmission gates TG 1 and TG 2 , which are synchronized with the clock signal CLK, and an inverter I 5 which generates a complement of the clock signal CLK. The second latch includes a second pair of inverters connected in antiparallel (L 5 ) and an output inverter I 4 . The second latch is configured to generate the true output signal Q and the complementary output signal QB. [0035] Based on the illustrated configuration of the scan chain latch unit 30 of FIG. 3B , setting the select signals SA and SB to a value of “00” will operate to turn on NMOS transistors N 1 and N 4 and PMOS transistors P 1 and P 4 . When this occurs, the value of the data at the data input port DI will operate to pull the output of the first totem pole arrangement high when DI=0 or low when DI=1. In contrast, setting the select signals SA and SB to a value of “11” will operate to turn on NMOS transistors N 5 and N 8 and PMOS transistors P 5 and P 8 . When this occurs, the value of the data at the serial input port SI will operate to pull the output of the first totem pole arrangement high when SI=0 or low when SI=1. Setting the select signals SA and SB to a value of “01” will operate to turn on NMOS transistors N 4 and N 5 and PMOS transistors P 1 and P 8 . When this occurs, the value of the feedback signal line Q will operate to pull the output of the first totem pole arrangement high when Q=0 and PMOS transistor P 7 is “on” or low when Q=1 and NMOS transistor N 7 is “on”. Finally, setting the select signals SA and SB to a value of “10” will operate to turn on NMOS transistors N 1 and N 8 and PMOS transistors P 4 and P 5 . When this occurs, the value of the feedback signal line QB will operate to pull the output of the first totem pole arrangement high when QB=0 and PMOS transistor P 3 is “on” or low when QB=1 and NMOS transistor N 3 is “on”. [0036] When the clock signal CLK is low (CLK=0), the output of the 4-input multiplexer is passed to an input of the first latch while the output of the first latch remains in a high impedance state by virtue of the fact that the second transmission gate TG 2 is “off”. When the clock signal CLK switches high (e.g., when a “launch” edge of the clock signal CLK occurs), the first transmission gate TG 1 is turned off, the second transmission gate TG 2 is turned on and the data at the output of the first pair of inverters L 4 is passed to an input of the second pair of inverters L 5 and the next state values of Q and QB are established. These values Q and QB are fed back to inputs of the 4-input multiplexer. [0037] The scan chain latch unit 30 ′ of FIG. 3C represents an alternative scan chain latch unit embodiment that utilizes a single feedback path from the true output Q and a feed-forward path from the data input port DI. As illustrated by TABLE 2, this scan chain latch unit 30 ′ supports a freeze mode of operation but not a toggle mode of operation. A more preferred embodiment of the scan chain latch unit 30 ′ of FIG. 3C is illustrated by the scan chain latch unit 30 ′″ of FIG. 3E , which has a reduced transistor count. The scan chain latch unit 30 ″ of FIG. 3D represents yet another scan chain latch unit embodiment that utilizes a single feedback path from the complementary output QB and a feed-forward path from the data input port DI. As illustrated by TABLE 2, this scan chain latch unit 30 ″ supports a toggle mode of operation but not a freeze mode of operation. A more preferred embodiment of the scan chain latch unit 30 ″ of FIG. 3D is illustrated by the scan chain latch unit 30 ″″ of FIG. 3F , which has a reduced transistor count. TABLE 2 OUTPUT OF LATCH OUTPUT OF LATCH UNIT 30″ SA SB UNIT 30′ and 30′″ and 30″″ 0 0 NS = DI; NORMAL NS = DI; NORMAL OPERATION OPERATION 0 1 NS = Q; FREEZE MODE NS = QB; TOGGLE MODE 1 0 NS = DI; NORMAL NS = DI; NORMAL OPERATION OPERATION 1 1 NS = SI; SCAN-IN MODE NS = SI; SCAN-IN MODE [0038] As illustrated by FIG. 4A , a scan chain register 40 according to another embodiment of the present invention includes a plurality of scan chain latch units 30 a - 30 n , which are illustrated in greater detail by FIGS. 3A-3B . This scan chain register 40 supports the four modes of operation illustrated by TABLE 1, with the SA and SB select terminals of the illustrated units 30 a - 30 n being connected to select lines SA and SB, respectively. Based on this configuration of the select lines and terminals, each of the scan chain latch units 30 a - 30 n will operate in the same mode of operation at all times. In contrast, the segment of a scan chain register 40 ′ illustrated by FIG. 4B demonstrates how a first select terminal SA of one scan chain latch unit 30 e may be connected to a second select terminal SB of another scan chain latch unit 30 f by a first select line S 1 . Similarly, the first select terminal SB of the scan chain latch unit 30 e may be connected to a second select terminal SA of the scan chain latch unit 30 f by a second select line S 2 . Based on this illustrated configuration, disposing the scan chain latch unit 30 e in a toggle mode of operation by setting S 1 , S 2 equal to 10 will operate to dispose the scan chain latch unit 30 f in a freeze mode of operation. Likewise, disposing the scan chain latch unit 30 e in a freeze mode of operation by setting S 1 , S 2 equal to 01 will operate to dispose the scan chain latch unit 30 f in a toggle mode of operation. [0039] This configuration of the scan chain latch units 30 e and 30 f enables at-speed testing of combinational logic devices. For example, all of the possible speed paths that can be tested in the two-input NAND gate ND 1 illustrated by FIG. 4B may be tested at-speed using the four test sequences illustrated by TABLE 3. The four test sequences also demonstrate the independence of the next states (NS) on the data values established at the serial input ports (SI) and the data input ports (DI) of the illustrated scan chain latch units 30 e and 30 f . TABLE 3 Z falling Z rising CS NS CS CS NS X 1  1  0  1  0 1 (NS = CS) (NS = /CS) (NS = CS) (NS = /CS) Y 1  0  1  0  1 1 (NS = /CS) (NS = CS) (NS = /CS) (NS = CS) S1 S2 01 10 01 10 [0040] In the event the 2-input NAND gate ND 1 of FIG. 4B is replaced by a 2-input XOR gate, then TABLE 4 illustrates the eight test sequences that may be required to test the 2-input XOR gate, with each sequence being independent of the data values established at the serial input ports (SI) and the data input ports (DI) of the illustrated scan chain latch units 30 e and 30 f . TABLE 4 Z rising Z falling CS NS CS NS CS NS CS NS X 0 0 1 1 0 1 0 0 1 1 0 1 Y 0 1 0 1 1 0 1 0 1 0 0 1 S1 S2 01 10 10 01 01 10 10 01 [0041] Increased controllability may also be achieved for more complex applications by inserting one or more dummy flip-flops into a scan chain register. As illustrated by FIG. 4C , a scan chain register 40 ″ may include a plurality of scan chain latch units 30 g - 30 i and at least one dummy flip-flop 32 , which is illustrated as a D-type flip-flop. Each of these latch units 30 g - 30 i may be configured as illustrated by FIGS. 3B-3F , however, other configurations of the latch units (not shown herein) may also be possible. Moreover, the latch units 30 g - 30 i need not be equivalent. The inputs (SA 1 , SB 1 ), (SA 2 , SB 2 ) and (SA 3 , SB 3 ) to each of the scan chain latch units 30 g - 30 i may be connected to respective pairs of terminals or may be connected in different ways to a single pair of input terminals (e.g., S 1 and S 2 ) to achieve desired functions for each of the latch units. The inclusion of this dummy flip-flop 32 (and others at strategic locations within the scan chain register 40 ″) may enable the at-speed testing of complex logic 34 with 100 percent controllability of the third input to the complex logic 34 (i.e., the last input of the complex logic 34 that is connected to output of scan chain latch unit 30 i ), albeit using a somewhat longer scan chain register 40 ″. The inclusion of one or more dummy flip-flops can enable all speed paths within the complex logic 34 to be checked using a smaller number of test vectors. As illustrated, the dummy flip-flop 32 may be programmed to store a desired next state for the following scan chain latch unit 30 i when the corresponding select signals SA 3 and SB 3 are set to a predetermined value. This value may equal a 11 value (i.e., SA 3 =SB 3 =1) in the event the latch unit 30 i is configured to operate in accordance with TABLES 1-2, however, alternative configurations of the latch unit 30 i (not shown herein) may also be utilized to achieve the desired operation. [0042] In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

An integrated circuit device utilizes a serial scan chain register to support efficient reliability testing of internal circuitry that is not readily accessible from the I/O pins of the device. This reliability testing includes the performance of, among other things, delay fault and stuck-at fault testing of elements within the internal circuitry. The scan chain register has scan chain latch units that support a toggle mode of operation. The scan chain register is provided with serial and parallel input ports and serial and parallel output ports. Each of the plurality of scan chain latch units includes a latch element and additional circuit elements that are configured to selectively establish a feedback path in the respective latch unit. This feedback path operates to pass an inversion of a signal at an output of the latch to an input of the latch when the corresponding scan chain latch unit is enabled to support a toggle mode of operation. Thus, if the output of the latch is set to a logic 1 level, then a toggle operation will cause the output of the latch to switch to a logic 0 level and vice versa. Because of the presence of a respective feedback path within each scan chain latch unit, the toggle operation at the output of a scan chain latch unit will be independent of the value of any other output of other scan chain latch units within the scan chain.

FIELD OF THE INVENTION The invention pertains to the field of using computational methods in predictive chemistry. More particularly, the invention utilizes a neural network with associated algorithmic functions, and the quantum mechanical properties of the molecules investigated or portions of those molecules, to optimize the prediction of bioactivity or the mode of chemotherapeutic action for molecules of interest. BACKGROUND OF THE INVENTION The role of medicinal chemist has not been altered in several decades. Their efforts to identify chemotherapeutic compounds, and thereafter devise more potent variations to them for medicinal use has long been one involving the arduous task of testing one compound at a time to determine individual bioactivity. This slow throughput system is made even more costly by the fact that historically over 10,000 compounds must be individually tested and evaluated for every one that actually reaches market as a therapeutic agent, as discussed in SCRIP, World Pharmaceutical News, Jan. 9, 1996, (PJB Publications). These facts have driven many scientists and pharmaceutical houses to shift their research from traditional drug discovery (e.g. individual evaluation) towards the development of high throughput systems (HTP) or computational methods that will bring to bear increasingly powerfull computer technology for the drug discovery process. To date none of these systems have been proven to significantly shorten discovery and optimization time for the development of chemotherapeutic agents. The first attempts to develop computational methods to predict the inhibitory potency of a given molecule prior to synthesis have been broadly termed quantitative structure activity relationship (QSAR) studies. These techniques require the user to define a functional relationship between a specific molecular property and a given molecular action. In the QSAR approach, or any approach where an individual is responsible for adjusting a mathematical model, the investigator must use variations in the structure of a molecule as the motivation for changing the value of coefficients in the computer model. For a chemical reaction as complex as an enzymatically mediated transformation of reactants to product, often an important part of therapeutic or medicinal activity, it is not possible to predict a priori all the effects a change to a substrate molecule will have on enzymatic action. This fact has made the QSAR approach to drug discovery exceptionally impracticable and inefficient. Accordingly, a need exists to optimize the prediction of bioactivity in chemical compounds such that the discovery and development of therapeutically valuable compounds is made more rapid and efficient. SUMMARY OF THE INVENTION Briefly stated, the invention described herein provides a neural network approach to the prediction of chemical activity in at least one molecule of interest. The example provided herein demonstrates how this methodology is useful in the prediction of bioactivity for a molecule capable of acting as an enzymatic inhibitor. This same methodology is also applicable to a variety of compounds of interest using the same training protocols and the same quantum mechanical properties of given molecules, or portions thereof discussed herein. The neural network provided herein is comprised of an input layer having at least one neuron where input data is sent and then given a vector value, a hidden layer having at least one neuron such that when data is received from the input layer that vector data is multiplied by a set weight and thereafter generates a weight matrix having the dimensions n by m where n is the length of an input vector and m is the number of hidden layer neurons available, and an output layer consisting of at least one neuron where the weight matrix data is sent before it is then sent to a transfer function. The transfer function is a non-linear equation that is capable of taking any value generated by the output layer and returning a number between −1 and 1. Feed-forward neural networks with back-propagation of error, of the type disclosed herein (see pages 7-10), are trained to recognize the quantum mechanical electrostatic potential and geometry at the entire van der Waals surface of a group of training molecules and to predict the strength of interactions, or free energy of binding, between an enzyme and novel inhibitors of that enzyme. More generally, the input for the functions of the neural network are the quantum mechanical electrostatic potentials of various molecules of interest. The predictive value of the system is gained through the use of a “training” process for the neural network using the known physicochemical properties of at least one training molecule, such as Inosine-Uridine Preferring Nucleoside Hydrolase (IU-NH). IU-NH is a nucleoside hydrolase from first isolated from the organism Crithidia fasciculata . The neural network is given input generated from the known electrostatic potential surfaces of the known molecules and attempts to predict the free energy of binding for that training set of molecules. When the neural network is able to accurately predict the free energy of binding of the training set of molecules, then the same neural network can be used with high accuracy to determine the free energy of binding, and hence the chemical characteristics, of unknown molecules. Among the novel aspects of the present invention is the utilization in the current invention of the quantum mechanical electrostatic potential of the molecule of interest at the van der Waals surface of that molecule as the physicochemical descriptor. The entire surface for each molecule, represented by a discrete collection of points, serves as the input to the neural network. In this way the invention utilizes quantum mechanical means to describe the molecular activity of a compound of interest. With improved knowledge of molecular activity the method described herein provides for enhancing the predictive value of neural networks with regard to phyisicochemical properties of compounds of interest either with regard to therapeutic compounds or compounds that would have other commercial or scientific value. The neural networks provided herein are useful in modeling chemical interactions that are non-covalent in nature. That is, as long as a reaction is mediated by electrostatic forces, including Van der Waals forces, the neural networks provided herein, and the associated algorithms, are accurate predictors of chemical activity and interaction. In this way they will save time and money in drug discovery and chemical evaluation processes. Specifically, with regard to enzymatic action, the neural networks herein described are able to determine chemical configurations that will optimize known chemotherapeutics and allow the discovery of new compounds that need to have specific binding characteristics or activity. These new compounds can be developed by modeling the quantum characteristics of specific molecular moieties with a trained neural or double neural network. According to an exemplary embodiment of the invention, a computational method has been developed to predict the free energy of binding for inhibitor or untested enzyme molecules. Other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawing(s) will be provided by the Patent and Trademark Office upon request and payment of the necessary fee. FIG. 1 shows a neural network with a back-propagation of error function, with an input layer i through n, a hidden layer j through m, and output layer p. The biases B are added to the hidden and output layers. FIG. 2 shows a double neural network comprised of a coupled inner and outer neural network. FIG. 3 a shows surface point comparisons of the geometry of unaltered input molecules 4 and 2 . FIG. 3 b shows surface point comparisons of the geometry of unaltered input molecule 4 and an idealized molecule 4 . FIG. 3 c shows surface point comparisons of the geometry of unaltered input molecule 2 and idealized molecule 2 . FIG. 4 shows a two dimensional representations of the molecules used in an exemplary study described herein. FIGS. 5 a and 5 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 4 , FIG. 5 a , with the double neural network idealized form of input molecule 4 , FIG. 5 c. FIGS. 5 b and 5 d show a surface point comparison of the geometry of unaltered input molecule number 4 , FIG. 5 b , with double neural network idealized form of input molecule number 4 , FIG. 5 d. FIGS. 6 a and 6 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 9 , FIG. 6 a , with the double neural network idealized form of input molecule number 9 , FIG. 6 c. FIGS. 6 b and 6 d show a surface point comparison of the geometry of the unaltered molecule number 9 , FIG. 6 b , with the double neural network idealized form of input molecule number 9 , FIG. 6 d. FIGS. 7 a and 7 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 14 , FIG. 7 a , with the double neural network idealized form of molecule number 14 , FIG. 7 c. FIGS. 7 b and 7 d show a surface point comparison of the geometry of unaltered input molecule number 14 , FIG. 7 b , with the double neural network idealized form of molecule number 14 , FIG. 7 d. FIGS. 8 a and 8 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 1 , FIG. 8 a , with the double neural network idealized form of molecule number 1 , FIG. 8 c. FIGS. 8 b and 8 d show a surface point comparison of the geometry of unaltered input molecule number 1 , FIG. 8 b , with the double neural network idealized form of molecule number 1 , FIG. 8 d. FIGS. 9 a and 9 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 12 , FIG. 9 a , with the double neural network idealized form of molecule number 12 , FIG. 9 c. FIGS. 9 b and 9 d show a surface point comparison of the geometry of unaltered input molecule number 12 , FIG. 9 b , with the double neural network idealized form of molecule number 12 , FIG. 9 d. FIGS. 10 a and 10 c show a surface point comparison of the electrostatic potential of unaltered input molecule number 15 , FIG. 10 a , with the double neural network idealized form of molecule number 15 , FIG. 10 c. FIGS. 10 b and 10 d show a surface point comparison of the geometry of unaltered input molecule number 15 , FIG. 10 b , with the double neural network idealized form of molecule number 15 , FIG. 10 d. DESCRIPTION OF THE PREFERRED EMBODIMENT The following abbreviations have designated meanings in the specification: Abbreviation Key High Throughput System: (HTP) Inosine-Uridine Preferring Nucleoside Hydrolase: (IU-NH) Quantitative Structure Activity Relationship (QSAR) p-aminophenyliminoribitol (pAPIR) Neural Networks The present invention discloses a neural network for improving the identification of chemically useful compounds without having to test each investigated compound individually. As is known in the art, a computational neural network is a computer algorithm which, during its training process, can learn features of input patterns and associate these with an output. Neural networks learn to approximate the function defined by the input/output pairs. The function is rarely, if ever specified by the user. After the learning phase, a well-trained network should be able to predict an output for a pattern not in the training set. In the context of the present invention, the neural net is trained with a set of molecules which can act as inhibitors for a given enzyme until the neural network can associate with every quantum mechanical description of the molecules in this set, a free energy of binding (which is the output). The network is then used to predict the free energy of binding for unknown molecules. Known computational neural networks are composed of many simple units operating in parallel. These units and the aspects of their interaction are inspired by biological nervous systems. The network's function is largely determined by the interactions between units. An artificial neural network consists of a number of “neurons” or “hidden units” that receive data from the outside, process the data, and output a signal. A “neuron” is essentially a regression equation with a non-linear output. When more than one neuron is used, non-linear models can be fitted. Networks learn by adjusting the values of the connections between elements (Fausett, L. FUNDAMENTALS OF THE NEURAL NETWORKS; Prentice Hall: New Jersey, 1994). The neural network presented by this invention is a feed-forward model with the back-propagation of error. This type of art recognized neural network learns with momentum. A back propagation neural network has three layers: an input layer, a hidden layer, and an output layer. The input layer is where the input data is sent. The link between the layers of the network is one of multiplication by a weight matrix, where every entry in the input vector is multiplied by a weight and sent to every hidden layer neuron, so that the hidden layer weight matrix has the dimensions n by m, where n is the length of the input vector and m is the number of hidden layer neurons. A bias is added to the hidden and output layer neurons. The hidden layer then functions to scale all the arguments before they are input into the transfer function. Each neuron has one bias. The function of the bias is to adjust the influence of neurons with greater and lesser roles in the model that the neural network is learning how to model. Neural Network Formulas Referring to the schematic in FIG. 1, the input layer 110 is represented by the boxes at the top-left of the figure. The weights 120 are represented by the lines connecting the layers: w ij is the weight between the i th neuron of the input layer and j th neuron of the hidden layer 130 and w jk is the weight between the j th neuron of the hidden layer 130 and the k th neuron of the output layer 190 . In FIG. 1 the output layer 190 has, as an exemplary example, only one neuron 191 because the target pattern is a single number, the binding energy (represented as “B p2 ”). The hidden layer 130 input from pattern number 1 for neuron 140 j, is h I j , and is calculated: h j 1  ( 1 ) = b j + ∑ i = 1 n     x i o  ( 1 ) × w ij Formula [1] where x o i is the output from the i th input neuron, w ij is the element of the weight matrix connecting input from neuron i with hidden layer neuron j and b j is the bias 150 on the hidden layer neuron j. This vector h I j is sent through a transfer function, ƒ. This function is non-linear and usually sigmoidal, taking any value and returning a number between −1 and 1, see page 4, (Fausett, L. FUNDAMENTALS OF THE NEURAL NETWORKS; Prentice Hall: New Jersey, 1994). A typical example is: f  ( h j 1 ) = 2 1 + e - h j 1 - 1 ≡ h j o Formula [2] The hidden layer output, h o j is then sent to the output layer 190 . The output layer input o i k is calculated for the k th output neuron o k 1 = b k + ∑ j = 1 m     h j o  w jk Formula [3] where w jk is the weight matrix element connecting hidden layer neuron j with output layer neuron k. The output layer output, o o k , is calculated with a similar transfer function as the one given above: g  ( o k 1 ) = γ 1 + e ( - o k 1 ) - η ≡ o k o Formula [4] where γ i is the range of the binding energies of the molecules used in the study and η i is the minimum number of all the binding energies. The minimum and maximum values are decreased and increased 10% to give the neural network the ability to predict numbers larger and small than those in the training set: min new =min old −abs (min old x .1),  Formula[5] max new =max old +abs (max old x .1)  Formula[6] The calculation of an output concludes the feed forward phase of training. The weights and biases are initialized with random numbers, during the first iterations the output of the network will be random numbers. Back propagation of error is used in conjunction with learning rules to increase the accuracy of predictions. The difference between o o k and the target value for input pattern number 1, t k , determines the sign of the corrections to the weights and biases. The size of the correction is determined by the first derivative of the transfer function. The relative change in weights and biases are proportional to a quantity δ k : δ k =( t k −o O k ) g′ ( o l k )  Formula[7] where g′ is the first derivative of equation 4. The corrections to the weights and biases are calculated: Δ w jk =αδ k h j o   Formula[8] Δ b k =αδ k   Formula[9] The corrections are moderated by α, the learning rate, this number ranges from zero to one exclusive of the end points. α functions to prevent the network from training to be biased to the last pattern of the iteration. The network's error should preferably be minimized with respect to all the patterns in the training set. The same learning rule is applied to the hidden layer weight matrix and biases. In most adaptive systems, learning is facilitated with the introduction of noise. In neural networks this procedure is called learning with momentum. The correction to the weights of the output layer at iteration number τ is a function of the correction of the previous iteration, τ−1, and μ, the momentum constant; Δ w jk ( τ )=αδ k h j o +μΔw jk ( τ −1)  Formula [10] Δ b k ( τ )=αδ k +μΔb k ( τ −1)  Formula [11] The same procedure is applied to the hidden layer weights and biases. The correction terms are added to the weights and biases concluding the back-propagation phase of the iteration. The network can train for hundreds to millions of iterations depending on the complexity of the function defined by the input/output pairs. This type of back-propagation is a generalization of the known Widrow-Hoff learning rule applied to multiple-layer networks and nonlinear differentiable transfer functions (Rumelhart, D. E.; Hinton, G. E.; Williams, R., J. Parallel Distributed Processing , Vol. 1; MIT Press: Massachusetts, 1986). Input vectors and the corresponding output vectors are used to train until the network can approximate a function. The strength of a back-propagation neural network is its ability to form internal representations through the use of a hidden layer of neurons. For example, the “exclusive or” problem demonstrates the ability of neural networks, with hidden layers, to form internal representations and to solve complex problems. Suppose four input patterns [(0,1) (0,0) (1,0) (1,1)] with output targets [1, 0, 1, 0], respectively are used. A perceptron or other single layer system would be unable to simulate the function described by these four input/output pairs. The only way to solve this problem is to learn that the two types of inputs work together to affect the output. In this case the least similar inputs cause the same output, and the more similar inputs have different outputs (Rumelhart, D. E.; Hinton, G. E.; Williams, R., J. Parallel Distributed Processing , Vol. 1; MIT Press: Massachusetts, 1986). The ability required to solve the aforementioned exemplary problem is not unlike that required to find the best inhibitor when it does not share all the same quantum features of the transition state. It is this inherent ability of neural networks to solve complex puzzles that makes them well conditioned for the task of simulating biological molecular recognition for a variety of molecule families including hydrolases, proteases, polymerases, transcriptases, phosphatases, and kinases. Each input neuron is given information (electrostatic potential or geometry) about the nearest point on the surface of the inhibitor. In this design each input neuron may be imagined to be at a fixed point on the sphere around the inhibitors, judging each inhibitor in the same way the enzyme active site would. Training a neural network requires variation of four adjustable parameters; number of hidden layer neurons, the learning rate, momentum constant and number of training iterations. One way to tell that a network is well trained is to minimize the training set prediction error. This can be calculated by taking the difference between the target i value for a molecule (experimentally determined binding energy), and the number the neural network predicted for that pattern i , and summing the absolute value of this number for all the molecules in the training set. As training progresses the training set prediction error will decrease. Minimizing training set error is not without negative consequence; over-training occurs when the network trains for too many iterations, has too many hidden layer neurons, has too large of a learning rate or too small of a momentum constant. One way to tell that a neural network has not been over-trained is to have it make a prediction for a pattern not in the training set. That is, see if the network can generalize from the information contained in the input/output pairs of the training set and apply that information to a molecule it has not trained with. In accommodation of this fact a training set of molecules is used as an “adjuster” molecule. This molecule is left out of the training set during training and used to check if the neural network was over-trained. The procedure is to train the neural network until the prediction set error has decreased until it plateau's. At this point the training procedure is ended and the resulting neural network is tested with the previously unused adjuster molecule or molecules. Preferably, if the neural network predicts the adjuster molecules binding energy within 5%, that neural network's construction is saved, if the prediction is more than 5% off, a new construction is chosen. This procedure is repeated until a construction is found that allows the neural network to predict the adjuster molecule's binding energy within 5%. This is done for all of the molecules in the training set, and the most common neural network construction is chosen as the final construction. The final construction for this system is 5 hidden layer neurons, ten thousand iterations, learning rate equals 0.1 and the momentum term equals 0.9. Quantum chemical data can also be input to train a neural network. As part of an exemplary description of a use of the present invention, quantum descriptions of molecules were created in the following way: First the molecular structures are energy minimized using semi-empirical methods. Molecules with many degrees of freedom, are configured such that they all have their flexible regions in the same relative position. Then the wave function for the molecule is calculated with an available software program Gaussian 94 (Gaussian 94, Revision C.2; Gaussian, Inc., Pittsburgh, Pa., 1995). Preferably, a variety of basis tests are used to insure converged results. From the wave function, the electrostatic potential is calculated at all points around and within the molecule. The electron density, the square of the wave function, is also calculated at all points around and within the molecule. With these two pieces of information the electrostatic potential at the van der Waals surface can be generated. Such information sheds light on the kinds of interactions a given molecule can have with the active site (Horenstein, B. A.; Schramm, V. L. Electronic nature of the transition state for nucleoside hydrolase—A blueprint for inhibitor design, Biochemistry 1993, 32, 7089-7097). Regions with electrostatic potentials close to zero are likely to be capable of van der Waals interactions, regions with a partial positive or negative charge can serve as hydrogen bond donor or acceptor sites, and regions with even greater positive or negative potentials may be involved in coulombic interactions. The electrostatic potential also conveys information concerning the likelihood that a particular region can undergo electrophilic or nucleophilic attack. Since molecules described by quantum mechanics have a finite electron density in all space, a reasonable cutoff is required to define a molecular geometry. One choice is the van der Waals surface, within which 95% of the electron density is found. One can closely approximate the van der Waals surface by finding all points around a molecule where the electron density is close to 0.002 ±δ electrons/bohr (Wagener, M.; Sadowski, J.; Gasteiger, J., Autocorrelation of molecular surface properties for modeling corticasteriod binding globulin and cytosolic Ah receptor activity by neural networks, J. Am. Chem. Soc. 1995, 117, 7769-7775). In this formula δ is the acceptance tolerance, δ is adjusted so that about 15 points per atom are accepted, creating a fairly uniform molecular surface, as shown previously (Bagdassarian, C. K.; Braunheim, B. B.; Schramm, V. L.; Schwartz, S. D., Quantitative measures of molecular similarity: methods to analyze transition-state analogues for enzymatic reactions. Int. J. Quantum Chem., Quant. Biol. Symp. 1996, 23,73-80)(Hammond, D. J.; Gutteridge, W. E.; Purine and Pyrimidine Metabolism in the Trypanosomatide, Molecular and Biochemical Parasitology , 1984, 13, 243-261). The information about a given molecular surface is thus described by a matrix with dimensions of 4×n where n is the number of points for the molecule, and the row vector of length 4 contains the x,y and z-coordinates of a given point and the electrostatic potential at that point. To preserve the geometric and electrostatic integrity of the training molecules, a collapse onto a lower dimensional surface is preferably avoided. The molecules are preferably oriented using common atoms and rotation matrices. Three atomic positions that all the molecules share are chosen and named a,b and c;−a is then translated to the origin, and this translation is performed on b and c and all the surface points. The basis set is rotated such that b is on the positive x axis. Then the basis set is rotated such that c is in the positive x, z plane. Inputs to a neural network must be in the form of a vector not a matrix. In an exemplary utilization of the present invention, the aforementioned transformation, the electrostatic potential of the different molecular surfaces was mapped onto a common surface; a sphere with a larger radius than the largest molecule in the study. The nearest neighbor for each point on the sphere is found on the surface of the molecule. The sphere is larger than the molecules so all mapping is outward. The electrostatic potential of this molecular point is then given the x, y and z coordinates of its nearest neighbor on the sphere. This mapping insures that similar parts of the molecules occupy a similar position in the input vector. The input to the neural network is a vector of these mapped electrostatic potentials and the distance the points were mapped from the molecular surface to the sphere. The information in the second half of the input vector are scalars that relate the distance, in Å (angstroms), between a point on the sphere and the nearest neighbor point on the molecule's surface. This portion of the input is designed to inform the neural network about the relative shapes and sizes of the molecular surfaces. In the limit term of the algorithms, with an infinite number of points, all mappings are normal to the inhibitor's surface, and the mapping distances will be as small as possible. To approach this limit a ten fold excess of points was selected to describe the molecules. The molecule's surfaces are described by 150 points per atom. The reference sphere that the points are mapped onto is described by a smaller number of points, 15 times the average number of atoms in the molecules of the study. As a result of mapping to the reference sphere all molecules are described by the smaller number of points. Double Neural Networks It is known in the art that neural networks can be used to predict how well molecules will function as inhibitors before experimental tests are done (Braunheim, B. B.; Schwartz, S. D. Computational Methods for Transition State and Inhibitor Recognition. Methods in Enzymology (In press); (Braunheim, B. B.; Schwartz, S. D.; Schramm, V. L. The Use of Quantum Neural Networks in a Blind Prediction of Unknown Binding Free Energies of Inhibitors to IU-Nucleoside Hydrolase, J. Am. Chem. Soc ., (Submitted)). The present invention, however, presents methods that can be used to design inhibitors that are more potent than those in the training set. Specifically, a double neural network has been devised whose function is to optimize the characteristics of molecules needed for bioactivity. A standard neural network, shown in FIG. 1, and whose function is determined by equations 1 through 10, is used to learn the rules of binding to the enzyme. Once a neural network has been trained to recognize what features of inhibitors are necessary to bind to the enzyme, this network is preferably integrated into another neural network to form a double neural network. The goal of this construction is to use these learned binding rules to discern how to create a quantum object which binds more strongly than any yet presented to the neural network. The trained and fixed network is called the inner network 210 and the other part is called the outer network 220 , as seen in FIG. 2 . The double network preferably has five layers and it is preferred that only the weights and biases between the first two layers 250 and 260 , respectively, are allowed to vary during training. That is, during the training of the double network, the outer network's weights and biases, 250 and 260 , respectively, are responsible for minimizing prediction set error. The inputs to the double network are preferably the same as the ones used to train the inner network, and input into first input layer 290 . The outer network's output layer 230 is the input layer to the inner network, therefore the output of the outer network is the input to the inner network. The inner network's output values 240 are the same as those used before, the difference being that they have been decreased by least 1ΔG/RT. Preferably, they are decreased 3ΔG/RT. That is, they are the binding energies of slightly better inhibitors. To reduce the error of the inner network the outer network must output altered descriptions of the input molecule, but altered in a way such that it describes an inhibitor with a greater affinity for the enzyme. The outer network becomes an inhibitor “improver” because the inner network's fixed weights and biases contain the rules for binding to the enzyme. In order to compensate for the altered binding energies the outer network must output altered versions of the input molecules that would bind to the enzyme with greater affinity. The inputs to the double neural network contain both electrostatic potential and geometrical information. During the training of the double neural network both of these descriptors are preferably allowed to vary. The range of the output functions of the output layer of the outer network 230 had to be modified in a similar way as that seen in formula 4 above, δ i (x)=(γ i /l+e (−x) )−η i   Formula [12] Where γ i is the range of the numbers at position i in the input patterns and η i is the minimum number at position i in the input patterns. Preferably, the double neural network trains for many iterations in the same fashion as mentioned before, the only difference being that there is no established rule which defines the correct training parameters. When the inner network was trained the optimum number of hidden layer neurons, training iterations, learning rate and momentum term could be found through trial and error by testing if the network could make a prediction for a molecule not in the training set. The competency of the outer network cannot be tested independent of the inner network. This being the case the endpoint for training of the double network is preferably chosen as the minimum number of iterations and hidden layer neurons that were needed to minimize training error such that more iterations and hidden layer neurons did not decrease the error significantly. One skilled in the art will recognize that the preferable parameters discussed herein are matters of design choice, and can be varied based upon the preferences and experience of the user. The preferred construction for the double network was 5 hidden layer neurons (in the outer network) and 1 million training iterations. Preferably, the learning rate and momentum term were the same values used to train the inner network. After the double neural network is trained, improved versions of the molecular descriptions are output. These improved versions of input molecules are then transformed back into three dimensional representations of molecules. With the molecules in this format it is possible to identify the molecular features that the neural network found could be altered to result in improved binding characteristics, or in other desirable characteristics dependent upon the intent of the user. To test the double neural network concept, typically an enzyme with known binding or other characteristics is employed in the neural networks herein disclosed such that the molecule is optimized for improved chemical characteristics. The enzyme chosen was nucleoside hydrolase. Use of Neural Networks in Biology Neural networks have previously been used in the art in the task of simulating biological molecular recognition, Gasteiger et. al. have used Kohonen self-organizing networks to preserve the maximum topological information of a molecule when mapping its three-dimensional surface onto a plane (Gasteiger, J.; Li, X.; Rudolph, C.; Sadowski, J.; Zupan, J., Representation of molecular electrostatic potentials by topological feature maps. J. Am. Chem. Soc . 1994,116, 4608-4620). Wagener et. al. have used auto-correlation vectors to describe different molecules. In that work (Wagener, M.; Sadowski, J.; Gasteiger, J. Autocorrelation of molecular surface properties for modeling corticasteriod binding globulin and cytosolic Ah receptor activity by neural networks. J. Am. Chem. Soc . 1995, 117, 7769-7775), the molecular electrostatic potential at the molecular surface was collapsed onto 12 auto-correlation coefficients. Neural networks were used by Weinstein et. al., to predict the mode of action of different chemical compounds (Weinstein, J. N.; Kohn, K. W.; Grever, M. R.; Viswanadhan, V. N.; Rubinstein, L. V.; Monks, A. P.; Scudiero, D. A.; Welch, L.; Koutsoukos, A. D.; Chiausa, A. J.; Paull, K. D. Neural computing in cancer drug development: predicting mechanism of activity, Science 1992, 258, 447-451 ). The effectiveness of these chemical compounds on different malignant tissues served as one type of descriptor for future neural network methodologies. The predictive target for the neural network employed by Weinstein et al., was the mode of action of the chemical compounds tested (e.g. alkylating agent, topoisomerase I inhibitor, etc.). Tetko et. al., used a similar autocorrelation vectors approach (Tetko, I. V.; Tanchuk, V. Y.; Chentsova, N. P.; Antonenko, S. V.; Poda, G. I; Kukhar, V. P.; Luik, A. I. HIV- 1 reverse transcriptase inhibitor design using artificial neural networks. J. Med. Chem . 1994, 37, 2520-2526). So et al., used neural networks to learn and to predict biological activity from QSAR descriptions of molecular structure (Fausett, L. FUNDAMENTALS OF THE NEURAL NETWORKS; Prentice Hall: New Jersey, 1994). Neural networks were used by Thompson et. al. to predict the amino acid sequence that the HIV-1 protease would bind most tightly, and this information was used to design HIV protease inhibitors (Thompson, T. B.; Chou, K. -C.; Zheng, C. Neural network predictions of the HIV-1 protease cleavage sites. J. Theor Biol ., 1995, 177, 369-379). As is known in the art, Neural networks are multi-dimensional non-linear function approximators. However, neural networks can also be used as a decision making algorithm because they require no assumptions about the function they are learning to approximate. This aspect of neural networks is important because it has been assumed in the prior art that the interactions between a chemical or enzymatic inhibitor and the active site of the molecule inhibited are determined by many aspects of the inhibitor and it would be impossible for an individual to a priori predict them all. In this sense the Schrodinger equation creates a complex, nonlinear relationship between a fixed enzyme active site and variable enzymatic inhibitors. However, as disclosed herein, this non-linear relation is what neural networks can be used to discover and in this way can be manipulated to simulate or predict biological activity. The neural network learns to approximate a function that is defined by the input/output pairs. In the current invention the input is preferably a quantum mechanical description of a molecule and the output is the binding energy of that molecule with the enzyme. After the neural network is “trained” with the quantum features of an appropriate set of molecules, of known bioactivity, this network construct has then “learned” the rules relating quantum descriptions to chemical recognition for that type of compound. The current inventions presents the way in which a neural network and/or a double neural network can be created which uses these rules to generate features that optimize bioactivity. The next section of the specification provides a generalization of the neural network concept to the “double neural network” of the current invention in which one neural network is trained to recognize binding features and a second coupled network optimizes these features. The next section of the specification contains application of the concepts to a specific multi-substrate enzyme IU nucleoside hydrolase. EXAMPLE 1 Nucleoside Hydrolase Protozoan parasites lack de novo purine biosynthetic pathways, and rely on the ability to salvage nucleosides from the blood of their host for RNA and DNA synthesis (Hammond, D. J.; Gutteridge, W. E., Purine and Pyrimidine Metabolism in the trypanosomatide, Molecular and Biochemical Parasitology , 1984, 13, 243-261). The inosine-uridine preferring nucleoside hydrolase (IU-NH) from Crithidia fasciculata is unique and has not been found in mammals (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex, Biochemistry, 1998, May). This enzyme catalyzes the N-ribosyl hydrolysis of all naturally occurring RNA purines and pyrimidines (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex, Biochemistry, 1998, May). The active site of the enzyme has two binding regions, one region binds ribose and the other binds the base. The inosine transition state requires ΔΔG=17.7 kcal/mol activation energy, 13.1 kcals/mol are used in activation of the ribosyl group, and only 4.6 kcals/mol are used for activation of the hypoxanthine leaving group (Parkin, D. W.; Limberg, G.; Tyler, P. C.; Fumeau, R. H.; Chen, X. Y.; Schramm,V. L. Isozyme—specific transition state inhibitors for the trypanosomal nucleoside hydrolase. Biochemistry , 1997, 36(12), 3528-3419). Analogues that resemble the inosine transition state both geometrically and electronically have proven to be powerful competitive inhibitors of this enzyme and could be used as anti-trypanosomal drugs (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). The transition state for these reactions feature an oxocarbenium-ion achieved by the polarization of the C4′ oxygen C1′ carbon bond of ribose. The C4′ oxygen is in proximity to a negatively charged carboxyl group from Glutamate 166 during transition state stabilization (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). This creates a partial double bond between the C4′ oxygen and the C1′ carbon causing the oxygen to have a partial positive charge and the carbon to have a partial negative charge. Nucleoside analogues with iminoribitol groups have a secondary amine in place of the C4′ oxygen of ribose and have proven to be effective inhibitors of IU-NH. IU-NH acts on all naturally occurring nucleosides (with C2′ hydroxyl groups), the lack of specificity for the leaving groups results from the small number of amino acids in this region to form specific interactions; Tyrosine 229, Histidine 82 and Histidine 241 (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). The only crystal structure data available concerning the configuration of bound inhibitors was generated from a study of the enzyme bound to p-aminophenyliminoribitol (pAPIR). As seen in FIGS. 7 a - 7 d , the Tyrosine 229 relocates during binding and moves above the phenyl ring of pAPIR. The side chain hydroxyl group of Tyrosine 229 is directed toward the cavity that would contain the six member ring of a purine, were it bound (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). Histidine 82 is 3.6 Å(angstroms) from the phenyl ring of pAPIR, and in the proper position for positive charge-π interactions to occur (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). Histidine 241 has been shown to be involved in leaving-group activation in the hydrolysis of inosine, presumably as the proton donor in the creation of hypoxanthine (Degano, M.; Almo, S. C.; Sacchettini, J. C.; Schramm V. L. Trypanosomal nucleoside hydrolase, a novel mechanism from the structure of a transition state complex Biochemistry, 1998, May). The molecules used in the study are fixed such that their structures are consistent for all molecules. In the experiments it was assumed that the enzyme will bind all molecules in a similar low energy conformation. In the present invention this approach has been developed through experimentation on flexible linear chain inhibitors such as the arginine analogues for nitric oxide synthase. The double neural network of the current invention need not know the configuration as long as the conformation of all molecules that are presented to the neural network are consistent. The known crystal structure of the inhibitor p-aminophenyliminoribitol bound to IU-nucleoside hydrolase was used as the model chemical conformation. The inosine transition state structure is stabilized by a negatively charged carboxyl group within the active site 3.6 Å from the C4′ oxygen (Horenstein, B. A.; Parkin, D. W.; Estupinan, B.; Schramm, V. L. Transition-state analysis of nucleoside hydrolase from Crithidia fasciculata. Biochemistry , 1991, 30,10788-1079520). In order to simulate this aspect of the active site, a negatively charged fluoride ion (at the same relative position of the nearest oxygen of the carboxyl group) was included in the calculations of the electrostatic potential at the van der Waals surface. To underscore the complexity of an investigation of this enzyme the different nature of transition state structures for the two different kinds of substrates was examined, purines and pyrimidines. Inosine's transition state is the only one for which there is a determined structure. The transition state structure for inosine is created by polarization of the ribosyl group across the C4′ oxygen C1′ bond, and protonation of N7 of the purine group. This protonation would be impossible when dealing with the pyrimidine uridine, as there is no place for this group to receive a proton (the electrons of N3 are involved in the ring conjugation). Therefore it is clear that these two types of substrates have quite different transition state structures, and that the rules of tight binding pyrimidine analogues is quite different from those of binding purines. For pyrimidines analogues, the binding energy tends to decrease with increasingly electron withdrawing substitutions. The opposite trend is seen with purine analogues. Any mathematical model of the binding preferences of this enzyme would have to take into account these contradictory trends with the different kinds of substrates. The prior art has determined that with this enzyme system a neural network could make accurate predictions for both purine and pyrimidine analogues when trained with purine and pyrimidine analogues (Braunheim, B. B.; Schwartz, S. D. Computational Methods for Transition State and Inhibitor Recognition. Methods in Enzymology. In press); (Braunheim, B. B.; Schwartz, S. D.; Schramm, V. L. The Use of Quantum Neural Networks in a Blind Prediction of Unknown Binding Free Energies of Inhibitors to IU-Nucleoside Hydrolase. J. Am. Chem. Soc. Submitted). However, with the double neural network of the current invention, there is an added level of complexity, because the inner neural network must teach the outer network during training. That is, when the outer neural network improves the molecular descriptions, it is necessary for purines to be improved in different way than pyrimidines. However, with the use of the double neural network, predictions concerning bioactivity are significantly more precise and effective than previously seen in the art. Surface Analysis of Tested Molecules Because chemical reactivity is controlled by quantum mechanical properties, it was determined that a method could be developed to train neural networks with ab initio quantum chemical data. This method of the current invention has proven itself to be highly accurate in the prediction of binding strengths of diverse inhibitors to a variety of enzymatic systems. The current invention describes a new methodology which optimizes these quantum features to predict and then produce substances of therapeutic value, or commercial value, either through the development of de novo compounds or by providing a molecular structure useful in the search of existing chemical databases. FIGS. 3 a - 3 c , show coincidentally oriented points on the surfaces of some of the molecules used in the study before and after their geometries were modified by the double neural network of the current invention. In FIG. 3 a a purine and a pyrimidine analogue are shown oriented for maximum geometric coincidence, the input molecules are numbers 2 and 4 in FIG. 4 . As seen in FIGS. 3 b and 3 c , the optimized versions of the input descriptions of molecules, are compared to their unaltered input descriptions. The neural networks developed herein have the capacity to rearrange the geometry of the inhibitors enough so that if a purine was input into the outer network it could output a pyrimidine to the inner network. In FIGS. 3 b and 3 c the outer neural network was not found to average the geometric descriptions for the two kinds of inhibitors. This is an important result because from the trends within the molecules of the study that purines bind more tightly as the electron withdrawing tendencies of substituents are increased and the opposite is true for pyrimidines. That is, the enzyme must deal with the two kinds of substrates and inhibitors in different ways, and it is important that the neural network deal with them in different ways as well. It has been determined that the neural network developed herein can learn the different binding rules for the different kinds of inhibitors. The important finding with the double neural network is that it when it is utilized the inner network is able to teach the outer network about the different binding rules as they apply to structurally different molecules. This evidence comes from the fact that purine and pyrimidine geometric characteristics were not averaged. Idealized Molecules Examination of the idealized molecules, their electrostatic potential and geometry, shows that the double neural network changed purines in different ways than it did for pyrimidines. The purine analogues 4 , 9 , and 14 were improved by the double neural network in similar ways. The lower right hand side of the surface points shown in FIGS. 5 a and 5 c show that the neural network improved molecule 4 by making that region more positive. The molecule's entire surface appears to be more positive (red points have a partial positive charge and blue have a partial negative charge), this is consistent with the other improved purines, see FIGS. 6 and 7. This is not surprising, the transition state for inosine is positively charged, it stands to reason that the neural network improve purines by making them look more like the tightest binding purine. In FIG. 7 molecule 14 is shown before and after its description was idealized. Molecule 14 is larger than the other purine analogues, the double neural network improved its description such that it geometrically more resembles the other purines. In order for the double neural network to do this it must have learned that purines analogues that more closely resemble the typical purine form function better. In addition, the double neural network operated on this purine analogue in a different way than it did for any of the other purine analogues. The double neural network of the current invention developed a set of operations that minimized part of the molecule's surface that were applied exclusively to molecule 14 . FIGS. 8 through 10 show that the double neural network idealized pyrimidines by making the lower part of the base more negative. An aromatic ring can be made to be more electron rich by a variety of substituents (Br, OH, NH 2 ) these groups themselves vary greatly in their electrostatic potential, notice how the neural network consistently made the lower portion of the ring more electron rich while the upper part of the ring (where the substituent groups were) is comprised of both positive and negative points. That is, the neural network learned from the molecules in the training set that the top part of the phenyl ring can vary greatly in electrostatic potential, but the electron richness of the mid and lower part of the phenyl ring determines binding strength. Design of Inhibitors and Chemotherapeutic Compounds With the effectiveness of the double neural network method provided above, the automation of inhibitor design, rapid drug discovery and/or optimization, and the construction of an apparatus to complete this work becomes possible. The final step of this method is going from the electrostatic potential at the van der Waals surface points to a description of the molecule of interest's atomic coordinates and atom type. This problem involves an increase in complexity going from the input to the output, and is solved by improving the ability of the inner and outer neural network to work together. Optimizing the Network Function The inner network was trained within its adjusted co-efficients it contains the rules for binding to the enzyme. Molecular descriptions, in this format can be input to this network and a prediction of binding energy will be output. To show the complexity of the function contained within the trained neural network a random number generator was used to provide output numbers, within the ranges of the molecular descriptions, and see if the function contained within the trained neural network could be optimized randomly. This approach was unsuccessful presumably because there are 400 descriptors in the molecular descriptions used, adjusting them randomly would take an almost infinite amount of time if an exhaustive search is required. Therefore it was determined that a smart search was necessary, that is, the search for every one of the 400 descriptors must be guided toward the optimum value. One problem with this is there is no way to know what the optimum value of the descriptors is until the patterns are presented to the trained neural network and an output is generated and even then, this output will not be able to determine which numbers in the input acted to increase and decrease the output. Typically, the only place in a neural network where the values of an input are judged for the degree to which they optimize any function is inside the network. The error term and corrections of the hidden layer are: δ j = f  ( h j 1 )  ∑ k = l m     δ k  w jk Formula [13]  Δ w ij =αδ j x i   Formula[14] Δ b j =αδ j   Formula[15] Equation 13 shows how the error term for the hidden layer, δ j , is a function of both the input to the hidden layer and the error of the output layer. Equations 14 and 15 show how the error term of the hidden layer is preferably used to calculate the correction terms for the input layer so in the next iteration, the error term will be smaller. This sequence shown in equations 13 through 15 shows how the total error of the network is used to adjust the weights and biases of layers separated from the output layer. The neural network is, in fact, optimizing the input to the hidden layer in spite of the fact that there is no preset optimum of what the hidden layer input should be. This ability of the learning rules to find a multi-dimensional optimum is exactly what is exploited in the double neural network of the current invention. The “teaching” of the outer network by the inner network occurs because the input layer's error term of the inner network is optimizing the weights and biases of the output layer of the outer network. The reason why quantum features optimization occurs is because the weights and biases of the inner network are fixed and because the true binding energies have been increased slightly. With these configurations the training rules for the double neural network of the current invention were forced to find the multi-dimensional optimum for the output of the outer network's output layer, which is based on minimizing the error of the input layer of the inner network. Preferably, the only way to do this is to output a molecular description that has a slightly larger binding energy than the one input to the outer network. In satisfying these requirements the outer network of the current double neural network becomes a molecular features “optimizer” based on the rules contained within the inner network. Methods For Generating Input From Quantum Chemical data A second method can be used to transform the three dimensional surfaces of molecules into a common set of points on a sphere that can then be modeled by the neural networks provided for herein. This transformation works in a similar way as the one layered out above, the first step of this algorithm is to find the angle between the vector defined by line between a point on the sphere and the origin, with the line that connects the origin with every point on the molecular surface. The computer being used is utilized to search through this collection of angles and find five points with the smallest angle. These points are closest to the line that connects the origin and the point of the sphere's surface. From these five points one point that is selected, this point is the one closest to the point of the sphere's surface. Its electrostatic potential is the first number of the input vector. The distance between them is the second number in the input vector. Five points are used in this method, those with the smallest angle, to find the one point closest to the point of the surface of the sphere (e.g. the smallest distance). The reason for this is that sometimes molecular surfaces are bent or sterically hindered and it is difficult to determine the surface facing away from the center of the molecule. With this method it is possible to determine that the part of the molecular surface with which the molecule of interest interacts is the outermost part of the molecular surface. In this way it is possible to insure that the double neural network of the current invention “sees” the most physically relevant part of the molecule as its input. Thus, it can be appreciated that a computational method and an apparatus therefore have been presented which will facilitate the discovery of novel bioactive and/or therapeutic molecules, these methods rely on the use of a neural network to recognize and predict binding affinity Accordingly, it is to be understood that the embodiments of the invention herein providing for a more efficient mode of drug discovery and modification are merely illustrative of the application of the principles of the invention. It will be evident from the foregoing description that changes in the form, methods of use, and applications of the elements of the neural network system and associated algorithms disclosed may be resorted to without departing from the spirit of the invention, or the scope of the appended claims.

A computational method for the discovery and design of therapeutically valuable bioactive compounds is presented. The method employed has successfully analyzed enzymatic inhibitors for their chemical properties through the use of a neural network and associated algorithms. This method is an improvement over the current methods of drug discovery which often employs a random search through a large library of synthesized chemical compounds or biological samples for bioactivity related to a specific therapeutic use. This time-consuming process is the most expensive portion of current drug discovery methods. The development of computational methods for the prediction of specific molecular activity will facilitate the design of novel chemotherapeutics or other chemically useful compounds. The novel neural network provided in the current invention is “trained” with the bioactivity of known compounds and then used to predict the bioactivity of unknown compounds.

FIELD OF THE INVENTION This invention relates to “active implantable medical devices” as defined by the Jun. 20, 1990 directive 90/385/CEE of the Council of the European Communities. BACKGROUND OF THE INVENTION The above-identified definition includes in particular devices that monitor cardiac activity and generate impulses of stimulation, resynchronization, defibrillation, and/or cardioversion in the event the device detects a disorder in heart rate. It also includes, for example, neurological devices, pumps for distribution of medical substances, cochlear implants, and implanted biological sensors, as well as devices for measurement of pH or bio-impedance (such as trans-pulmonary impedance or intracardiac impedance measurements). With such devices, it is possible to operate a data exchange with a “programmer,” which is an external instrument that can be used to check the parameter settings of the devices, to read information recorded by the devices, to register information with the devices, and to update the internal control software of the devices. This data exchange is carried out by telemetry, i.e., by a technique of remote transmission of information, without galvanic contact. Until now, telemetry has primarily been carried out by magnetic coupling between coils in the implanted device and the programmer, which is a technique known as “process by induction.” This technique has certain disadvantages, however, because of the low range of an inductive coupling, which necessitates placing a “telemetry head” containing a coil in the vicinity of the implantation site of the active implantable medical device. Implementation of a different nongalvanic coupling technique has been proposed, using the two components of an electromagnetic wave produced by emitting/receiving circuits operating in the field of radio frequencies (RF), typically at frequencies around a few hundred MHz. This technique, known as RF telemetry, makes it possible to program or interrogate implants at distances greater than 3 meters, and thus carry out information exchanges without having to use a telemetry head, and even without intervention of an external operator. U.S. Patent Application Publication Nos. US2003/0114897 and US2003/0149459 describe implants and programmers equipped with such RF telemetry circuits. These RF circuits require, however, a current supply that is greater than what is necessary for the other circuits of the implant (e.g., the stimulation and detection circuits). For example, the current consumption of an RF circuit can exceed 3 mA during emission phases. In the case of defibrillators, taking into account the significant amount of current required by circuits used to apply shock therapy, the batteries used have low internal resistance and can supply without difficulty currents of about a few mA. On the other hand, pacemakers and similar devices, such as multisite or resynchronization devices, are generally supplied by small-size lithium-iodine batteries (or their equivalent), taking into account the low operating current required by the stimulation and detection circuits. These batteries have an internal resistance of about 100 Ω at the beginning of their life, which can increase to 1 kΩ, 2 kΩ, or more as the battery discharges. This internal resistance is not a problem for circuits with low consumption, but can prevent one from being able to provide RF circuits with the required level of current. A first solution is to use a different type of battery, for example, a reduced size lithium-manganese (LiMnO 2 ) weldable button battery with low impedance. There are such batteries whose characteristics are: diameter 12.2 mm, height 1.4 mm, capacity 27 mA/h, nominal voltage 3 V, self-discharge maximum 1% per annum, and which can provide currents of several mA. The current of RF circuits is exclusively provided by the button battery. When the button battery can no longer provide the current, the lithium battery of the pacemaker can provide a low current of 10 μA, which allows the transmitter-receiver to work in pulsated mode. The peak current is provided by a capacitor belonging to a supply circuit controlling the voltage of the battery. OBJECTS AND SUMMARY OF THE INVENTION The present invention provides a novel solution to the above-identified problem, which does not require recourse to an additional battery, due to a circuit making it possible to provide to an RF telemetry circuit incorporated in an implant the high current necessary for operation. For this purpose, the device of the invention, which includes a principal circuit, an auxiliary RF telemetry circuit, and a supply battery for the principal and auxiliary circuits, comprises, between the supply battery and the auxiliary circuit, a regulating circuit including an accumulator of electric power, coupled with the auxiliary circuit to deliver a current ready to feed this auxiliary circuit, and a load circuit coupled with the supply battery to maintain this accumulator with a predetermined level of load. The accumulator can be a rechargeable battery or a condenser. When the voltage corresponding to the predetermined level of load is higher than the voltage delivered by the supply battery, the load circuit includes a voltage multiplying stage. Advantageously, the load circuit is a circuit with intermittent and cyclic operation. The cyclic report/ratio can be a variable report/ratio function of the internal resistance of the supply battery, with the relative duration of the feeding cycles of the regulating circuit decreasing when the aforementioned resistance or level of load increases. The load circuit can stop the load of the accumulator when the terminal voltage level of the accumulator reaches a predetermined upper limit, when the charging current of the accumulator reaches a predetermined lower limit, or after completion of a given maximum duration. BRIEF DESCRIPTION OF THE DRAWINGS One now will describe an example of implementation of the device of the present invention, by reference to the annexed drawings, wherein the same numerical references indicate identical elements from one figure to another and: FIG. 1 is a simplified circuit diagram of the various elements constituting the feeding circuit of the invention; FIG. 2 shows details of the voltage multiplier of the circuit of FIG. 1 ; and FIGS. 3 and 4 show the charge and discharge configurations of the voltage multiplier of FIG. 2 according to the commutation states of the various switches. DETAILED DESCRIPTION OF THE INVENTION One now will describe an embodiment of the device of the invention, which can in particular be applied to the active implantable medical devices marketed by ELA Medical, Montrouge, France, such as the Symphony and Rhapsody-branded devices. These are devices with a programmable microprocessor comprising circuits to receive, format, and treat electric signals collected by implanted electrodes, and to deliver stimulation impulses to those electrodes. Adaptation of these devices to the implementation of the functions of the present invention is deemed to be within the ability of persons of ordinary skill in the art, and will not be described in detail (with regard to its software aspects, the invention can be implemented by suitable programming of the operating software of the pacemaker). In FIG. 1 , reference 10 indicates generally the RF telemetry circuits, which require a relatively high supply current (several mA), in particular during emission phases of the modulated signal. To deliver such a supply current, the invention proposes supplying these RF circuits starting from an accumulator 12 , itself charged by the supply battery 14 of the implanted device by means of a regulating circuit 16 . The supply battery 14 also supplies other circuits of the device (e.g., the detection and stimulation circuits). Accumulator 12 can be an accumulator of the lithium-ion type, of which there are models of reduced size having characteristics compatible with the supply requirements for RF circuits in implanted devices, typically: capacity 10 mA/h, internal resistance 25 Ω uninterrupted and 8 Ω into alternate, self-discharge maximum of 15% per annum, and rechargeable 250 times with a maximum loss of capacity of 14%. Such accumulators are in particular manufactured by the company Quallion LLC, Sylmar, Calif., USA. Alternatively, the lithium-ion accumulator can be replaced by a condenser of very strong rated capacity, typically about 1 Farad. The lithium-ion accumulators present a nominal voltage of 4 V at full load, which can then decrease to a value of about 3 V. Because the lithium-iodine batteries used in cardiac pacemakers have a nominal voltage of about 2.8 V, this voltage is insufficient to charge the accumulator 12 and it is therefore necessary to use an intermediate stage voltage multiplier 18 , making it possible to deliver to the accumulator a charging voltage of 2.8V×1.5=4.2 V. This voltage multiplier 18 is connected to the supply battery 14 by a switch 20 and to the accumulator 12 by a switch 22 . Its operation, and thus the load of the accumulator 12 , is controlled by a control circuit 24 , which includes a load checking circuit 26 whose entry is connected to a reference voltage standard V ref and to the point between voltage divider resistors 28 , 30 , which gives an indication of the terminal voltage of accumulator 12 and is brought into service by closing switch 32 . The internal structure of the voltage multiplier 18 is illustrated in FIG. 2 . It includes an entry 34 connected via switch 20 to the supply battery 14 , making it possible to charge a first condenser 36 by closing a switch 38 . This same entry also makes it possible to charge two condensers 40 , 42 assembled in series, by closing a switch 44 . In addition, a switch 46 makes it possible to connect the point between condensers 40 , 42 to the point between condenser 36 and switch 38 . Lastly, a switch 48 makes it possible to short-circuit the circuit formed by condensers 40 and 42 . In the initial phase, corresponding to the configuration of FIG. 3 , switches 20 , 38 , and 44 are closed, while switches 22 , 46 , and 48 are open. Condenser 36 is thus charged with the voltage of the battery (2.8 V) and condensers 40 and 42 are each charged with half of this voltage (1.4 V). In the subsequent phase, switches 20 , 38 , and 44 are opened, while switches 22 , 46 , and 48 are closed. Condensers 40 and 42 are then in parallel, and the voltage on their terminals (1.4 V) is added to the boundaries of condenser 36 (2.8 V), thus giving an exit voltage of 2.8+1.4=4.2 V. This voltage of 4.2 V produced by the voltage multiplier 18 is used to charge accumulator 12 , with a charging current which can vary from 2 to 0.1 mA, for example, according to changes in the internal resistance of the battery 14 . Advantageously, this load of the accumulator 12 is operated in an intermittent and cyclic way, for example, with a 25% load during a cycle of 1 second, the remaining 75% being devoted to the supply of the other circuits (e.g. the detection and stimulation circuits) of the device. Advantageously, the cyclic report/ratio (25% in the example above) is a variable report/ratio, a function of the internal resistance of the supply battery 14 (the duration of the phases of load becoming shorter when internal resistance increases) and/or of the load level of accumulator 12 (the duration of the cycles of load decreasing as the accumulator 12 approaches its level of maximum loading). The load of the accumulator 12 continues thus until reaching a predetermined level, for example, when the load checking circuit 26 detects that the terminal voltage of the accumulator has reached 4 V. The load checking circuit 26 then operates to suspend the load until the terminal voltage of the accumulator 12 has fallen below a given threshold due to energy consumption by the RF circuits. The load also can be stopped according to other criteria, for example, when the charging current reaches a low limit because of accumulator 12 , or at the end of a given maximum duration, for example, at the end of 100 hours for 10 mA of charging current. RF circuits 10 , supplied with the energy stored in accumulator 12 , could be fed satisfactorily with a relatively significant output current, for example from 3 to 20 mA. To take into account the difference between the terminal voltage of the accumulator (about 3 to 4 V according to the level of load) and the level of nominal voltage required for the supply of RF components (typically between 1.8 and 3 V), use of an adapted regulator is envisaged, for example, a linear or self-inductive regulator, to generate the supply voltage wanted with a suitable capacity while running. One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments which are presented for purposes of illustration and not of limitation.

An active implantable medical device having an RF telemetry circuit. The device is in particular a stimulation, resynchronization, defibrillation and/or cardioversion device. It includes a principal circuit, an RF telemetry auxiliary circuit and a supply battery for the principal and auxiliary circuits. It is envisaged to have between the supply battery and the auxiliary circuit a regulating circuit including an accumulator of electric power coupled with the auxiliary circuit to deliver a current ready to feed the auxiliary circuit, and a load circuit coupled with the supply battery to maintain the accumulator on a predetermined level of load.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Application No. 62/049,651 filed on Sep. 12, 2014, and U.S. Provisional Application No. 62/128,296, filed Mar. 4, 2015, and is a continuation-in-part of U.S. application Ser. No. 14/217,058, filed Mar. 17, 2014, which claims the benefit of priority to U.S. Provisional Application No. 61/790,771 filed on Mar. 15, 2013, the disclosures of which are incorporated by reference herein. BACKGROUND OF THE INVENTION The first portion of the background is most closely related to a single element preturbine oxidation catalyst element for EMD turbocharged engines using twisted exhaust runners. Oxidation catalysts (OC) are used to reduce the emissions of unburned hydrocarbons (HC), carbon monoxide (CO) and certain types of particulate matter (PM). Of the aftertreatment systems used on lean burn engines, this is the simplest system as it is completely passive and practically maintenance free. In the art these are also commonly referred to as diesel oxidizing catalysts (DOC). When dealing with both diesel engines and gas engines the shortened term oxidation catalyst (OC) is the more appropriate term. A very common use of an OC has been in the aftertreatment of diesel truck engines where the OC is placed downstream of the turbocharger, and upstream of the diesel particulate filter (DPF). Because locomotives have become so tightly packaged, there is minimal room for a downstream OC in the locomotive application. A solution to this called a V-Cat has been patented and developed by Miratech. With a V-Cat system the OC is built into the exhaust manifolds on the engine upstream of the turbocharger, hence a pre turbine OC. For packaging reasons, this system had a single OC substrate for each cylinder. ASME Paper JRCICE2007-40060 titled ‘Exhaust Emissions From a 2,850 kW EMD SD60M Locomotive Equipped With a Diesel Oxidation Catalyst’ describes the application and testing of prototype V-Cat system on a 16 cylinder EMD engine in an SD60M locomotive. The primary parameter that determines the emissions reduction efficiency of an OC is its temperature. Results of the V-Cat testing in the ASME paper indicate the CO reduction efficiency reaches 90% at around 200 C, the peak HC reduction efficiency is approximately 50% at 320 C. Not only does the preturbine placement of this OC system on the turbocharged EMD engine offer a solution to the packaging problem, preturbine placement of the OC has several other benefits. As the efficiency of the OC is affected by temperature, its pre turbine placement will substantially increase its overall operating temperature. Notch 4 has a temperature drop across the turbo of 41 C. Notch 4 is when the preturbine temperature finally reaches 310 C where the OC starts to reduce HC at 50% efficiency. If the OC were downstream of the turbo in this case, it would be operating at the mid 40% range. At notch 8, the temperature difference across the turbo is 137 C. These increases in preturbine temperature will be even more important in the future when methane becomes a regulated emission. Typical OC systems do not efficiently remove methane until 400 C. With a preturbine OC system this would start at notch 4, with a downstream OC this may not start until notch 7. When hydrocarbon emissions are regulated for natural gas engines, they regulate only non-methane hydrocarbons. In natural gas engines the methane component of total HC is typically close to 90%. Although methane is not a criteria pollutant with direct human health risks, air agencies are paying more attention to methane emissions as a potent greenhouse gas with regulations for it pending in the near future. One interesting finding in the ASME report is that the preturbine OC actually increased the turbo inlet temperature and overall engine efficiency because of the energy released when it oxidized the CO, HC and PM matter. This led to an actual increase of engine thermal efficiency at some points even though the additional back pressure of the OC would typically cause a decrease in efficiency due to reduced airflow. Another advantage of a preturbine OC over a downstream OC is the effect of the OC system back pressure. Downstream of the turbo, whatever back pressure the OC causes would be multiplied by the pressure ratio of the turbo turbine. So if the OC caused a pressure drop of 1.1 kPa and the turbo had a pressure ratio of 2.7, the back pressure increase in the exhaust manifold would be 2.9 kPa. In the case of the preturbine DOC, the OC pressure drop is not multiplied. As noted, the V-Cat system tested in the ASME paper had a single OC substrate per cylinder. This system is now in production and sold exclusively by EMD the manufacturer of the EMD engines. Because of the way the exhaust manifold segments are tightly packaged across the top of the engine and there is only a short 4 inch length of common exhaust plenum before the turbo charger inlet plumbing, there was no easy way to package a single large substrate that all of the exhaust would flow through equally. The solution was to have a single OC substrate for each cylinder and therefore each cylinder would experience the same pressure drop and the engine would run smoothly. If a single large substrate was attempted and each cylinder was affected differently, performance would suffer as some cylinders would get more intake air than others. In the report the pressure drop was measured across one substrate with the engine running, the measured pressure drop was 1.1 kPa. While accurately measured, this pressure drop is not representative of the instantaneous pressure drop that affects the scavenging of the cylinder and how much intake air is brought into the cylinder. Because the exhaust valves are open substantially and flowing exhaust for less than a ⅓ of the crank rotation, it is likely that this measured average pressure is actually ⅓ of what would be allowed with a single substrate for all of the cylinders when the exhaust pulses are all combined together into one average exhaust manifold mass flow. Early versions of this single substrate per cylinder OC system suffered substrate failures that were attributed to the pulsing effect of the exhaust gases flowing rapidly through the substrate for only ⅓ of the crank rotation. This resulted in the substrates breaking up into small pieces and flowing through the exhaust manifold towards the turbo inlet. Fortunately the EMD engine has a built in debris screen installed in front of the turbo inlet to prevent material such as this from damaging the turbine blades. Later designs of the preturbine OC system overcame this problem by adding additional material and substrate supports to enhance the durability of the substrates. While the existing preturbine OC solution for the EMD engine solves the packaging problem, it would be preferable if a more economical and simpler single substrate solution could be found that did not have to replace every one of the existing exhaust manifolds. The second portion of the background is most closely related to adjustable inlet guide vanes for improved emissions in EMD locomotives. Two aftertreatment systems have been developed and tested for emissions reductions in EMD powered locomotives, and both test programs noted a spike in particulate matter (PM) emissions for notch 6 engine loading. Miratech has developed and patented a preturbine diesel oxidizing catalyst (DOC) system call the V-Cat, testing results were published in ASME Paper JRCICE2007-40060 titled ‘Exhaust Emissions From a 2,850 kW EMD SD60M Locomotive Equipped With a Diesel Oxidation Catalyst’. This system was focused on reducing PM emission and from Notch 3 to Notch 8, the system efficiency averaged over 55% except for Notch 6 where the reduction plummeted to approximately ½ that value at 27%. Overall this system reduced PM by 52%. Engine, Fuel and Emissions Engineering has trademarked its Compact SCR and the final report documenting its system on a Metrolink passenger locomotive is available on their website at www.efee.com. Unlike the preturbine V-Cat system, the Compact SCR system was located downstream of the engine turbocharger exhaust outlet and its primary function was to reduce oxides of nitrogen (NOx). It has a secondary function of reducing PM and was capable of reducing PM by 61% on the locomotive duty cycle. The testing with the Compact SCR resulted in a similar PM emissions spike at Notch 6 as seen in the V-Cat DOC testing. Further the NOx reduction efficiency of the Compact SCR system at throttle setting of idle through Notch 2 were very low. The notch 6 increase in PM emissions and the low load reduction in NOx reduction efficiency are due to two different characteristics of the EMD 2 stroke locomotive engine. The notch 6 PM increase is due the engine air fuel ratio starting to be less lean than optimum which decreases combustion efficiency of the diesel spray and increases soot which is a major part of diesel PM. On the other hand the low load reduction in SCR efficiency is because the engine air fuel ratio is becoming too lean and the exhaust temperature is very low. These varied air fuel ratios are a function of the design of the turbocharged EMD 2 stroke engine. The EMD system has a unique combination supercharger and turbocharger. It is driven by the engine geartrain through a one way clutch up until the point that there is enough exhaust energy to drive the turbocharger faster than the gear train. The point where the turbo spools up is typically notch 7 and that is where the boost builds up and the engine runs a leaner air fuel ratio that produces less PM. At very low loads the engine is also at low RPM, but at these lower speeds the intake ports are open for a longer time giving the reduced boost pressure more time to drive fresh air into the cylinder. Also at these lower loads the engine actually needs less air because it is making less power and consuming less fuel. This causes the engine to take in even more air than is needed and this excess air in the combustion chamber lowers the exhaust temperature. At idle this problem is at its worst as the low RPM allows a long time for scavenging and the minimal engine fuel consumption further drives down the exhaust temperature. From a peak exhaust temperature over 500 C at notch 8, the exhaust temperature is just over 110 C at idle and 160 C at Notch 1 . Energy Conversion Inc. (ECI) in Tacoma, Wash. has had to overcome an additional problem in its conversion of these EMD 2 stroke engines to natural gas. In order to prevent detonation at high loads with natural gas, it was required to lower the compression ratio of the engine. Lowering the compression ratio at idle exacerbated the low RPM combustion temperature issue and in order to get lower emissions at idle, ECI incorporated a bank idling system where it only injected fuel into the cylinders on one side of the engine. This allowed each cylinder to operate with twice the amount of fuel and generate twice the amount of power. Every two minutes the engine would swap banks and run on the other half of the engine. In addition to the bank idling technique, ECI devised an inlet throttle system to restrict the amount of air that the engine took in at idle to further increase the combustion temperature and increase the exhaust gas temperatures. This system had a set of rotating vanes pointing inward from a ring. This ring would be in front of the turbocharger compressor and had an open and closed setting. In the open setting the vanes would turn so that they were lined up in the direction of airflow and offered minimal resistance to the airflow. In the closed position an air actuator would rotate the vanes almost 90 degrees until the vanes touched and closed off the air passage except for the small round opening left over at the tips of the vanes. This inlet restriction system developed by ECI is similar to variable angle inlet guide vanes used on some gas turbine engines and large stationary compressor equipment. When the guide vanes are in the neutral position they have no effect on the compressor upstream of them. When the guide vane are rotated from the neutral position they will add swirl to the flow, this swirl will have a different effect on airflow through the compressor depending on whether the swirl is turning the airflow with or against the rotation direction of the compressor impeller. If the flow is swirling in the direction of the centrifugal impeller rotation then the amount of pressure rise across the impellor will decrease as the impellor will not be able to put as much work or energy into the flow. This would tend to decrease the amount of mass flow across the compressor and the boost pressure leaving it. If the inlet guide vanes were turned in the opposite direction, the resulting airflow swirl would turn the air against the impeller rotation. This would increase the amount of work or energy that the impellor will impart into the airflow increasing the pressure rise. If the centrifugal impellor was part of a turbocharger, this increase in pressure rise would result in slowing down the impeller and turbine. This could be a form of limited waste gating for limiting or reducing the turbocharger shaft speed. In addition to the lower compression ratio causing lower combustion temperatures at lower loads, the ECI natural gas conversion systems changed the airflow configuration of the engine enough that the stock EMD turbocharger could overspeed at notch 8. In order to control overspeed ECI added a waste gate system to bypass some of the high temp exhaust gasses and reduce turbine speeds. Another system implemented by ECI in its conversion system is improved aftercooling of the intake air to reduce detonation at high loads. At low loads this improved intake air cooling would exacerbate the low combustion temperature issues at lower throttle settings. The solution was to revert the aftercooling system back to the original system for notches 3 down to idle where heated engine coolant is used to warm up the intake air. This required adding an actuated coolant control valve and some plumbing to control whether heated or cooled water was flowing to the liquid cooled aftercoolers. What would be beneficial in these applications would be an airflow control system that reduced the excessively lean low load mixtures, increased boost and airflow at notch 6 , and limited turbine speed in dual fuel engines at notch 8 . The third portion of the background is most closely related to a sonic and dual stage gas inlet valve. In the case of the ECI conversions systems for 2 stroke locomotive engines, a system called low pressure direct injection (LPDI) is used where the natural gas is injected directly into the cylinder during the compression stroke. What this leads to is a mixing challenge where the air and fuel have limited time to mix as the piston rises up to top dead center right before ignition. This mixing challenge is why SwRI on their single cylinder development EMD 710 engine decided to do premixing of the air and fuel even though it would not be practical on an ‘in service’ engine as too much unburned fuel would blow through the cylinder into the exhaust while scavenging. The in cylinder mixing issue can make prechamber operation difficult if a rich pocket of air and gas gets pushed into the prechamber which already has excess fuel in it. In this instance the prechamber will misfire and there will be no combustion for that stroke. For this reason ECI installed ‘jet caps’ on the first iteration spark ignited prechamber (SIP) system on the Napa Valley Wine train. The jet cap is an additional cap fixed over the end of the main Gas inlet valve (GIV). The GIV had a poppet valve at the end that controlled the flow of fuel gas into the combustion chamber. With the ‘jet cap’ in place, after the gas flowed thru the GIV body and past the poppet valve, it then had to flow through a small orifice at the end of the ‘jet cap’. This addressed several issues, all the gas was converged into one flow stream that now had higher velocity and was pointed away from the prechamber. Another difference between the ECI kit and the system tested at SwRI is that the ECI system has to operate at very high Lambdas. Lambda is the ratio of the actual air/fuel ratio divided by the stoichiometric air/fuel ratio. Typical 4 stroke diesel engines operate at Lambdas around 1.9 at low load to 1.4 at full power. The SwRI single cylinder development engine didn't have to operate below 50% power. At low loads, an EMD 2 stroke locomotive operates at Lambda's above 3 and at idle the Lambda can exceed 4. At these very high lambdas it would require a larger prechamber that will produce fewer NOx emissions and have a lower thermal efficiency. A solution to the very high Lambda value is to restrict inlet flow with a throttling system at low loads. This will allow operating the engine all the way from idle to full load with smaller volume prechambers that put out less NOx emissions and operate at higher thermal efficiency. In a uniflow 2 stroke engine, scavenging is a process of blowing inlet air over the top of the piston at bottom dead center. This entering intake air pushes the spent combustion gasses out through the open exhaust ports at the top of the cylinder. The amount of in cylinder air motion and mixing as the piston rises in the compression stroke is proportional to how much velocity the inlet air carried in with it due to excess intake air box pressure. When the inlet is throttled to help reduce the low load air fuel Lambda, a large portion of this mixing energy is lost. It is possible to reduce the inlet air box pressure to a low enough value that not enough inlet air enters to thoroughly scavenge the cylinder and some amount of exhaust gas will remain in the cylinder when the exhaust valves close. This effect can be desirable or have negative effects. This left over combustion gas is much hotter and less dense than the incoming air, so the resulting in cylinder air mass will now be lower and the average in cylinder temperature will be hotter at the beginning of the compression stroke. This has the double effect of both lowering the Lambda for easier combustion with less ignition energy using a smaller prechamber, and also faster and more efficient combustion because the compressed air fuel mixture is already much hotter at ignition. This is referred to as internal exhaust gas recirculation (EGR) where exhaust gas is purposely left behind to achieve these effects. In a uniflow 2 stroke, the downside of this is much less air velocity at intake port closing. This lowered in cylinder velocity and mixing energy reduces the amount of air and fuel mixing when the natural gas is injected at low loads. A supersonic injector for gaseous fuel engines as described in U.S. Pat. No. 6,708,905 would be a solution that offers improved mixing and a bonus of lower temperature gas when injected. This particular device has two drawbacks. First it has many machined parts with complicated features that will be costly. Second, the design has a built in cavity where residual natural gas will be compressed into and remain unburned during the combustion event. Most of the compressed gas in this cavity will become methane exhaust emissions. This release of unburned methane is both a pollution emissions problem and an energy efficiency problem. What is desired is an economical and practical way to achieve the benefits of a high velocity and focused sonic injection nozzle without the added cavity for residual unburned methane, better mixing in the combustion chamber of a natural gas engine with direct gas injection which would allow operating a uniflow 2 cycle engine to be throttled past the point that internal EGR effects are improving combustion. The fourth portion of this background is most closely related to prechamber cooling sleeves. Prechamber ignition systems are used to ignite air fuel mixtures that are too lean for a spark plug to ignite. The type of prechamber discussed here is a small prechamber at less than 5% of the combustion chamber clearance volume. Combustion inside of the prechamber will be easier to start and burn much more rapidly because the air fuel mixture is hotter and typically richer than the air fuel mixture in the main combustion chamber. The cooling of a prechamber is one of the challenges, and the most challenging part of the prechamber to cool is the nozzle or tip area. This is because there is combustion happening on both sides of it. With insufficient cooling it has been documented that overheating prechambers will often melt the tip of the prechamber. Sometime before the tip actually melts, it will cause preignition which will limit how much power the engine can produce or cause the engine to run improperly during some conditions. An improved prechamber would be a design that has better cooling for the prechamber body, prechamber tip and nozzle area while also being more economical to make. The fifth portion of this background is most closely related prechamber cylinder deactivation on spark ignited prechamber EMD engines. Both the roots blown and turbocharged EMD engines would be good candidates for cylinder deactivation. Currently ECI used skip firing in their Spark Ignited Prechamber systems to improve combustion at very low loads where the engine operates very lean. In skip fire, the engine controller will skip actuating the main injector for a certain cylinder. This will cause the other cylinders to have to operate at a higher power to make up the lost power from the deactivated cylinders. When operating at higher power the other cylinders will need more fuel to generate it and this increase in fuel to those cylinders is what decreases how lean those cylinders are before ignition which generates higher heat release rates making the combustion events more consistent, and efficient. The control system has a strategy to alternate the deactivated cylinders to prevent any one cylinder from becoming significantly cooler than the others and also to prevent lube oil build up in that cylinder. To keep the system simple, only the main gas injector is turned off for the cylinders that are skipped. All of the engine prechambers are still fed natural gas and the spark plugs are still fired. In the case where the prechamber supply pressure can be held constant over the entire engine operating range, the prechamber fuel supply system consists of only a single mechanical pressure regulator with a fixed setting. Because the prechamber is still fed fuel, but the main chamber is not, there is no guarantee that the mixture in the prechamber is being burned when a cylinder is deactivated, even when the spark plug is still being fired. A portion of the fuel burned in the prechamber during normal combustion was not injected by the prechamber fuel system, but was brought in from the main chamber. When the cylinder is deactivated the air pushed into the prechamber by the piston will not have any fuel so the overall mixture in the prechamber may be too lean for the spark to burn. This is greatly dependent on engine speed and load while being skip fired. Because skip fire happens at low load it's likely that the extended time the system gets to fill the prechamber offsets this deactivated cylinder issue, but at the same time the operating cylinders are running richer and having the deactivated cylinders prechambers rich enough to fire may make the activated prechambers too rich causing misfires or combustion instability. With these issues in mind, prechambers that are fed fuel in deactivated cylinders are likely to generate more NOx or HC or both. The generation of Non-Methane HC emissions is especially problematic as after the spark plug initiates combustion in the prechamber some unburned natural gas is pushed out of the prechamber into the main chamber before it is burned inside the prechamber. The sixth portion of this background is most closely related to continuous water injection for ECI converted engines. Water injection has been used in engines to reduce engine knock at higher power levels as far back as World War 2. It was commonly used to allow aircraft engines to generate extra power during takeoff and other possible events that needed the most power possible. It has also seen some use in racing applications, typically in sprint type racing where the time duration of full power and water injection use is limited, thus avoiding a bulky and heavy water storage system. There are several issues that make water injection not worth the effort of implementation in most mobile applications; one is the volume and weight of the consumable water and second is the need to refill the container that would store it. Once these issues are overcome, then there is the environmental issue of keeping the stored onboard water from freezing when the vehicle is not in operation. Another issue is the challenge of corrosion to the hardware that would be used to inject it, especially if the injector is designed to open and close rapidly for each cylinders combustion cycle. Finally is the corrosion issue as related to any other parts. If after shut down an injector would leak water into the engine cylinder during engine storage, that cylinder will have internal corrosion and suffer significant maintenance issues. Several Papers have indicated that direct injection of water into the engine cylinder has several advantages in addition to reducing engine knocking SAE paper 2009-01-1925 Effect of In Cylinder Water Injection Strategies on Performance and Emissions of a Hydrogen Fueled Direct Injection Engine is one good example. In this paper it is indicated that water injection both lowered NOx emissions and increased the indicated thermal efficiency when the water injection happened during the compression stroke. This effect was much less when the water was injected during the intake stroke on the four stroke engine tested. When converting a diesel engine over to operate on natural gas, the compression ratio is typically reduced. If it wasn't reduced the engine may be limited to only generation of 60% of its original diesel operation rated power. The addition of water injection could allow the retention of higher compression ratios. BRIEF SUMMARY OF THE INVENTION The first portion of the summary is most closely related to a single element preturbine oxidation catalyst element for EMD turbocharged engines using twisted exhaust runners. With one revised exhaust manifold segment there is a way to use a single OC substrate without significantly affecting the exhaust flow of the cylinder closest to the turbocharger. This single substrate would replace the debris screen at the inlet to the turbo. This substrate would be installed in the last exhaust manifold segment before the turbo. Room for the substrate would be created by modifying the exhaust manifold runners for the last two cylinders. The typical exhaust runners are a 9″×4″ rectangular tube. The 9 inch dimension on the runner is along the axial flow path of the exhaust manifold segment. By having the rectangular tube transition from a 9″×4″ shape to a 4″×9″ shape as it meets the exhaust manifold segment, it will free up approximately 5″ of axial length for a 5 ″ long OC substrate. This single substrate system will save the cost of making 3 extra exhaust manifold segments and 15 extra OC substrates. By averaging the exhaust pulses all together in one flow, it minimizes the pulsing effect on the substrate and the substrate experiences relatively consistent and smooth exhaust flow. By replacing the original debris screen it removes the effect of the pressure drop of the screen which helps to offset the pressure drop of the OC substrate on engine performance. The holes in the OC substrate will be smaller than the holes in the original debris screen so it will be more effective at stopping smaller bits of debris from damaging the turbine blades and reducing the turbo performance. The long OC substrate in front of the turbo converging duct acts as a flow straightener removing any swirl in the flow that may have been caused by the exhaust runner pulses entering the exhaust manifold close to the turbo inlet. The second portion of the summary is most closely related to adjustable inlet guide vanes for improved emissions in EMD locomotives. With minor development and the addition of a modulated position actuator, the ECI inlet throttle system could be used to variably reduce the airflow in the EMD engine in very small increments. If the modulated position actuator had more than 90 degrees of travel it could also be used to increase boost at notch 6 and decrease turbine speed at notch 8. The beneficial effects of restricted airflow at idle has been demonstrated with the inlet throttle restrictor fully closed in previous ECI natural gas conversions. In notches 2 and 3 where the engine loading is getting higher and detonation is not a threat it is beneficial to have higher intake air temperature so that the natural gas will combust easier. Current ECI dual fuel systems do not consume natural gas in notches 1 or 2 , and at notch 3 natural gas substitution is limited to 65% because the combination of very lean mixtures and low compression make it difficult to ignite the natural gas. Because of the way 2 stroke engines scavenge, it would be possible with a variable inlet guide vane system to drop the intake air pressure and flow enough that all of the burned exhaust gases were not pushed out by the incoming intake air. This is referred to as internal exhaust gas recirculation (EGR) and has several benefits when used at low loads. Because the left behind exhaust gases are much hotter than the incoming intake air, the in cylinder temperatures of the mixed intake and EGR gases will be higher. Also because the EGR gases were hotter, they would be less dense. As the cylinder pressure when the intake ports and exhaust valves are closed will be almost the same, this hotter less dense mixture will have less mass. This will make the air fuel ratio less lean. The combination of a less lean mixture that is also hotter at the start of ignition will improve the combustibility of the natural gas and will increase the amount of gas at notch 3 that can replace diesel fuel, and will also allow the substituting of some natural gas for diesel fuel at notches 2 and 1 , possibly even at idle. If the system is effective enough it could eliminate the need for the coolant diverter valve used to help preheat the intake air. This variable inlet restriction would also be a benefit to a diesel fueled EMD engine that is using a Compact SCR system, as it can drive the exhaust temperature up at idle, and notches 1 through 3 where the Compact SCR system was not functioning or was less than 30% efficient. These increases in combustion efficiencies at low loads due to the less lean mixtures and potential internal EGR will not only reduce emissions, they will increase thermal efficiency at these low loads. The third portion of the summary is most closely related to a sonic and dual stage gas inlet valve. What is proposed here is a gas inlet valve (GIV) that utilizes the valve head and valve seat at a narrower angle than 120 degrees on the prior art GIV to accelerate the incoming natural gas flow and direct it further away from cylinder walls. This configuration has several advantages. First it merely requires a change in operating pressure and revised machining on two components to gain this effect. Second, as the gas exits from an annulus instead of a hole, the gas exits as a cone formed from a sheet of gas with both an inner surface and outer surface. This surface is where the mixing happens and this design will have over twice the surface area for entraining the surrounding air. Third, as the nozzle is formed by the movement of the poppet valve from the seat, the stoke can be adjusted to different sonic throat areas. Allowing longer valve opening times at higher pressures and lower flows. This design completely eliminates the issue of residual unburned gaseous fuel remaining inside of a cavity in the GIV or Jet Cap after combustion. These sonic GIV units can operate with any gaseous fuel including propane and hydrogen. The fourth portion of this summary is most closely related to prechamber cooling sleeves. Proposed is a two piece prechamber body and nozzle design that enhances the cooling of the prechamber by incorporating a separate cooling sleeve to insure that an adequate amount of cooling fluid makes it to the bottom of the prechamber, and then evenly flows around the periphery of the prechamber to a point past the top of the inner prechamber combustion chamber wall. The fifth portion of this summary is most closely related to an OPOC variable compression ratio mechanism While the OPOC engine being developed by ECO Motors is not an EMD 2 Stroke engine as currently used in locomotives. It does offer interesting possibilities as a power plant for genset type locomotives or as a Head End Power generator engine for passenger locomotives. The value of the OPOC's low weight and volume compared to its power output are even higher for these application when there is an effort to operate the locomotive on an alternate fuel. A typical diesel engine design converted to natural gas will need to be scaled up 30% bigger in size to make the same power. Because of the unique nature of the OPOC engine design, it is possible to incorporate an infinitely adjustable variable compression ratio (VCR) using an outer wrist pin with an offset inner wrist pin bore. A sliding spline fit is used to control the rotation of the outer wrist pin, because this is a two stroke engine, the piston will always be under compression when operating so that all of the VCR component slop should be taken up. The only wear items would be the parts of the sliding spline and they are replaceable without having to remove the piston. The sixth portion of this summary is most closely related to group cylinder deactivation on prechamber ignited EMD engines. Proposed is the deactivating of groups of cylinder in the EMD engine by not firing the main GIV injector and also by interrupting the flow of fuel to the prechambers. The configuration of the EMD and its firing order make this a reasonable prospect. In another embodiment, the simple control valve that turns on and off the supplemental fuel to the groups of prechambers could be replaced by an advanced prechamber fuel pressure control module (PPCM) which would offer other engine operating advantages. Proposed is an integrated pressure supply module using two or more PMW valves to control the prechamber pressure supply. This would be a single module that only needed a low voltage power source and the operating pressure command. It would then read the operating pressure of its own gas rail pressure sensor and control the valves. At higher flows with multiple valves, one or more of the valves could be left open full time and then one or two of the other valves manipulated in a PWM fashion. This ability to leave a valve open full time minimizes the wear on the valve and extends its service life. With multiple valves the job of operating in PWM mode can be alternated between valves to equalize valve life. On an engine platform like a locomotive where steady state loads are common, this alternating the duty cycle of valves allows the PPCM to also check the valves against each other. This allows determining if one valve of the set is malfunctioning, and if the PPCM has an extra valve capacity it could send a warning fault code that it needs service in the future while still functioning. When used for cylinder deactivation on an EMD engine, comparing the operation of each PPCM to each other to maintain the same prechamber rail supply pressure would be a good way to detect prechamber check valve issues. If one PPCM indicated a higher or lower duty cycle or flow, then that would indicate something was wrong in the group of prechambers belonging to that PPCM. Many issues could cause this fault, a disconnected prechamber feed line, a stuck prechamber check ball, a leaking prechamber ball and seat or a clogged prechamber body feed hole are some possibilities. Now that prechamber fuel supply can be varied and banks of prechambers are being turned on and off with some form of cylinder deactivation, it will be beneficial to vary the prechamber fuel supply pressure when turning on the prechambers. When a bank of prechambers is turned back on, they will have cooled down from operating temperature and will have trouble firing a leaner mixture. At this point the PPCM should be commanded to operate at a slightly higher pressure temporarily so that the mixture is closer to stoichiometric and will be ignited by the spark plug easier and burn quicker. Once the prechamber is hot, the PPCM can be instructed to lower the supply pressure so the prechambers run leaner and produce less NOx. The seventh portion of this summary is most closely related to continuous water injection for ECI converted EMD engines. If it were possible to directly inject water into an Energy Conversions Inc (ECI) converted EMD engine, it may be possible to make enough power with the stock piston compression ratio that a piston change can be avoided during conversion. This saves a significant amount of labor and cost, plus has the benefit of higher efficiency and/or lower NOx emissions. Effective direct injection of water into an ECI converted EMD 2-stroke engine could be accomplished by injecting the water into the body of the hydraulically actuated natural Gas Inlet Valve (GIV). This will mix it with the fast moving natural gas that is then injected into the engine cylinder during the compression stroke. This allows direct injection of the water without having to create a new custom cylinder head with an additional passage for an additional injector with access to the combustion chamber. This is most applicable to engines using Low Pressure Direct Injection Systems (LPDI) where the natural gas is injected into the engine during the compression stroke at only a few hundred psi, whereas High Pressure Direct Injection (HPDI) operates its injectors at pressures above 4000 psi and would be a challenge to combine the water with the gas and also only open for a few degrees of crank rotation. Unlike 4 stroke engines, the airflow is only at a high velocity as it goes though the liner ports. In a typical port injected engine, the water can be sprayed into the air in the inlet port which is only momentarily stationary and will then all be at a high velocity as it is inducted into the engine cylinder. In the uniflow 2 stroke airbox the airflow for the most part travels slowly up until it radially approaches the liner ports at which point it will achieve its highest velocity. This is because the air in a 4 stroke engine goes through a nearly constant cross section intake runner up to the combustion chamber, where as a uniflow 2 stroke engine has a larger plenum of intake air around the liner that only speeds up as the flow streams merge on their way to a liner port. While fumigating a 4 cycle engine intake runner can be effective, this makes fumigating the airbox area of a uniflow 2 stroke with atomized water challenging without risk of water separating out and causing puddles. Unlike on road truck diesel engines and automobiles that attempt to operate at high loads at as low an RPM as possible. In a locomotive operating cycle the engines speed or RPM will increase as load is increased. Because the water is only needed at higher RPM, it may be possible to use a Continuous Injection System (CIS) to inject the water into the GIV. At higher RPM the GIV may spend up to 35% of its time open and flowing gas. Intuitively it would seem that pulsing of the water would be needed, but similar to early versions of port fuel injection, the water mist in the GIV could be sprayed continuously. In the case of port fuel injection, air would be flowing by the injectors less than 25% of the time and it would not be flowing fast. In the case of the 2 stroke GIV system, the GIV could be open longer and the natural gas and atomized water mixture would be flowing at sonic speed. This eliminates the cost and complexity of having a high speed on-off water injector at each cylinder. It also reduces the needed water line size to each injector as the fluid flows continuously instead of only 25% or less of the time. The ECI conversion system combined with CIS water injection has another water injection system benefit. Because the ECI conversion system regulated the main natural gas supply to 110 psi, and then reduces it to actual GIV operating pressure using the Gas Flow Control Valve (GFCV), it would be possible to purge the water injection system of all water after engine shutdown by taking main pressure 110 psi natural gas and purging the water injection system with it. By doing this at a higher RPM, but lower load, the GFCV will be operating the GIV's at much lower pressure and the incoming natural gas will force the water through the system after a certain amount of time. In order for this to work, the areas that need to be cleared of water need to flow downhill to the water injection nozzle at the GIV. If this purge gas were to be fed to the water injection through a specific fixed orifice it would be possible to sense when the water lines and injector nozzles were clear of water by sensing the pressure drop in the water injection manifold. As natural gas will flow much more quickly through the water injection nozzles than the actual water would, once the system is free of water, the pressure in the water injection manifold will drop. Further by monitoring this pressure, system health and clogged nozzles can be detected. Both by the rate of manifold pressure drop and how much it dropped. The eighth portion of this summary is most closely related to groupings and configurations of prechamber orifices for turbulent jet ignition (TJI). In order to adequately capture the effect of TJI, the orifice has to be small enough to quench the burning air and fuel mixture as it exits the prechamber passing thought the orifices. In order to do this, orifices as small as 0.050 inch diameter may be needed. As the size of the orifice gets smaller, the prechamber jets will penetrate less distance into the combustion chamber and have a reduced effect in two ways. First the ignition will happen closer to the center of the combustion chamber reducing the effectiveness of the multiple ignition points to decrease the total burn duration. The second negative effect of the smaller orifice jet is that there will be less accumulated partially burned air and fuel in the pockets that are formed by the small jets. These pockets of combustion radicals may end up being dilute enough or in a small enough local quantity to not ignite consistently or ignite with enough energy to initiate rapid combustion of the lean air fuel mixture around the pocket. Proposed is to have groups of a higher number of smaller nozzles configured so that two or more nozzles converge in the combustion chamber. This will help over come the penetration and concentration issues with smaller nozzles while keeping the delayed combustion benefits of the smaller nozzle quenching effects on delayed combustion for more rapid heat release rates. In another embodiment all or some of the prechamber jets can be offset from the prechamber axis to generate swirl in the prechamber combustion chamber. With the spark plug typically on one side of the prechamber and the supplemental fuel injected on the opposite side, the mixture in the prechamber combustion chamber may remain significantly stratified if the air and fuel mixture from the main chamber is injected straight up into the chamber. In the worst case, this stratification of the charge can lead to possible misfires at certain engine loads. Charge stratification will also result in slower and inconsistent heat release in the prechamber. In one embodiment, a prechamber assembly includes a cylinder head including a coolant cavity, a prechamber body located within the cylinder head, the prechamber body including a nozzle, and an annular sleeve radially surrounding a portion of the prechamber body. The sleeve includes a plurality of coolant inlet holes. A portion of the prechamber body is radially spaced from the sleeve to form a coolant sleeve annulus extending along a length of the prechamber body above the coolant inlet holes. The coolant cavity and the coolant sleeve annulus are in fluid communication through the plurality of coolant inlet holes. In a further embodiment, the sleeve further includes a plurality of coolant outlet holes, and the plurality of coolant inlet holes is positioned towards the end of the coolant sleeve annulus closest to the nozzle. In another embodiment, the coolant outlet holes are in fluid communication with a coolant return cavity. In other embodiments, the prechamber assembly includes a coolant comprising water. In another embodiment, the prechamber body includes a feed groove distal from the nozzle and in fluid communication with the cooling cavity, and the coolant cavity spans from the feed groove to the plurality of coolant inlet holes. In a still further embodiment, the prechamber assembly further includes a coolant comprising engine oil. In some embodiments, the sleeve and the nozzle are integral. In a further embodiment, a prechamber assembly includes a cylinder head including a coolant cavity and a prechamber body located within the cylinder head. The prechamber body comprises a nozzle that includes a plurality of jets directing flow through the nozzle at an angle other than parallel or perpendicular relative to a longitudinal centerline axis of the nozzle. The plurality of jets are clustered in groups radially spaced apart from each other around the longitudinal centerline axis of the nozzle. In some embodiments, the groups of jets are equally spaced radially. In other embodiments, flow through the jets of each group of jets converges at a distance from the nozzle. In a still further embodiment, each group of jets comprises two jets. In another embodiment, the nozzle further includes a centerline jet aligned along the centerline axis. In further embodiments, the nozzle further includes a centerline group of jets aligned approximately parallel to the centerline axis, wherein flow through the centerline group of jets converges at a distance from the nozzle. In a still further embodiment, a prechamber assembly includes a cylinder head including a coolant cavity; and a prechamber body located within the cylinder head, the prechamber body including a nozzle. The nozzle includes a plurality of jets, each jet aligned along a respective axis that is offset from a centerline axis of the nozzle such that the jet axes do not intersect the centerline axis. In some embodiments, the nozzle includes a mixing area, and wherein each jet axis of the plurality of jets is offset an equal distance from the centerline axis such that flow through the plurality of jets causes a rotating flow about the centerline axis in the mixing area of the nozzle. DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a typical 16 cylinder EMD turbocharged engine as used in locomotives. FIG. 2 is a side view of the same engine in FIG. 1 except that the exhaust system has been revised to accommodate a single substrate OC system. FIG. 2A is an isometric view of a prior art exhaust runner. FIG. 2B is an isometric view of an embodiment of an exhaust runner of the engine of FIG. 2 . FIG. 2C is an isometric view of an embodiment of an OC substrate of the engine of FIG. 2 . FIG. 3 is a side view of the prior art Miratech preturbine V-Cat system. FIG. 4 is a side view of an EMD 16 cylinder illustrating the location of the Variable Inlet Guide Vane Unit. FIG. 5 is an isometric view of the turbocharger and the Variable Inlet Guide Vane Unit with its blades closed. FIG. 6 is an isometric view of a prior art Variable Inlet Guide Vane Unit with the blades partially open. FIG. 7 is an isometric view of an ECI manufactured gas inlet valve (GIV). FIG. 8 is cross section view of a conventional poppet valve in the open position of a prior art GIV. FIG. 9 is a cross section view of the revised poppet valve and valve seat insert to achieve sonic gas injection flow. FIG. 10A is a cross section view illustrating a dual stage hydraulic valve assembly in the closed state. FIG. 10B is a cross section view illustrating a dual stage hydraulic valve assembly in the fully open state. FIG. 10C is a cross section view illustrating a dual stage hydraulic valve assembly in the partially open state. FIG. 11 is a cross section view of an EMD cylinder head with a prechamber installed. FIG. 12A is an enlarged view of the prechamber body of the EMD cylinder head of FIG. 11 . FIG. 12B is an enlarged, fragmentary view of the prechamber body of FIG. 12A . FIG. 13A is a Section View of a truck engine cylinder head with a prechamber assembly installed. FIG. 13B is an enlarged view of the XXX of the truck engine cylinder head of FIG. 13A . FIG. 14 is an exploded view of an OPOC engine Variable Compression Ratio system. FIG. 15A is a table illustrating the firing order variations for a 12 cylinder EMD 2-stroke engine. FIG. 15B is a table illustrating the firing order variations for a 16 cylinder EMD 2-stroke engine. FIG. 16A is a section view of a prechamber nozzle with grouped and offset TJI jets. FIG. 16B is an isometric view of a prechamber nozzle with a single axial TJI jet. FIGS. 17-22C illustrate additional views of nozzles including TJI jets. DETAILED DESCRIPTION To facilitate an understanding of the present disclosure, a number of terms and phrases are defined below: Gaseous Fuel: The predominant gaseous fuel used in internal combustion engines is natural gas consisting mostly of methane, but with minor modifications these engines could consume any gaseous fuel including but not limited to propane, natural gas and hydrogen. In this document the term natural gas and gaseous fuel are used interchangeably. Hydrocarbon (HC): Emissions resulting from incomplete combustion. Main Charge: The air fuel mixture in the main combustion chamber space between the piston top and the cylinder head. If an opposed piston engine, this would be the space between the opposed piston faces. Particulate Matter (PM): Particulate matter is a criteria pollution emitted from many sources. In this document we will commonly refer to it simply as PM. It could include both diesel soot PM that is considered toxic in California or the type of PM created by the consumption and combustion of lube oil from an engine. While still considered PM as a criteria emission, the PM from lube oil consumption is considered less toxic than diesel soot. The first portion of the detailed description is most closely related to a single element preturbine oxidation catalyst element for EMD turbocharged engines using twisted exhaust runners. FIG. 1 is a side view of a typical 16 cylinder EMD turbocharged engine as used in locomotive and marine applications. In this prior art configuration Engine 2 has an exhaust system along the top of it. The exhaust system is composed of three exhaust collector segments 4 and one turbocharger adapter exhaust collector segment 8 that collect the exhaust gases from the 16 engine cylinders into one combined exhaust mass flow. Each one of these exhaust collector segments connects to 4 of the engines 16 cylinders, with exhaust gases flowing from an individual engine cylinder to an exhaust collector segment through an exhaust runner 6 . The standard exhaust runner 6 is a 4 inch by 9 inch rectangular tube as illustrated in FIG. 2A . The longer 9 inch dimension is shown along FIG. 1 as going left to right and the four inch dimension is normal to FIG. 1 . The exhaust gasses flow in a direction from the bottom of the Figure through an exhaust runner 6 up into an exhaust collector segment. Each exhaust collector segment has two pairs of exhaust runners 6 , only one is visible as the second exhaust runner 6 of each pair is directly behind the first exhaust runner 6 . In some version of the EMD engines, the pairs of exhaust runners 6 are combined together into one larger runner. Sometimes this larger runner would have a shared wall in between, keeping the exhaust gases from the two cylinders separate until they mixed with the combined exhaust flow in the exhaust collector segments. In other cases this was missing or removed and the exhaust gases from the pair of engine cylinders would mix in the combined exhaust runner 6 volume before mixing with the combined exhaust flow in the exhaust collector segments. This would appear the same in FIG. 1 and functionally does not affect this description of the prior art. The three exhaust collector segments 4 and one turbocharger adapter exhaust collector segment 8 are connected to each other by flexible bellows 5 at three places. The now combined exhaust gasses flow from the turbocharger adapter exhaust collector segment 8 thru debris screen housing 10 and small flexible bellows 12 into the turbocharger inlet 14 . As the combined exhaust mass flows through the debris screen housing 10 , it must pass through debris screen 16 . Debris screen 16 is a metal plate installed in debris screen housing 10 with a large number of small holes that will allow the exhaust gases to flow through it, but will block any small solid parts from traveling with the exhaust gases into the turbocharger and damaging the turbine blades. This debris screen 16 does cause a small pressure drop in the exhaust system which reduces engine performance and efficiency, but it prevents damage to the turbocharger assembly in the case of a component failure elsewhere in the engine. This is a valuable trade off as the turbocharger is one of the most expensive parts of the engine. FIG. 2 is a side view of the same engine in FIG. 1 with a revised exhaust system to include a single substrate OC system. Engine 2 ′ has similar components in its exhaust system upstream of turbocharger adapter exhaust collector segment 8 ′ and downstream of debris screen housing 10 ′. The primary difference is the deletion of the debris screen 16 and the addition of the OC substrate 18 into modified turbocharger adapter exhaust collector segment 8 ′. Turbocharger adapter exhaust collector segment 8 ′ has been modified to allow the OC substrate 18 as shown in FIG. 2C to slide into it. The primary modification to make this possible is the reshaping of exhaust runner 6 ′. Where exhaust runner 6 had a consistent 9 inch by 4 inch rectangular shape along its path as shown in FIG. 2A , the cross section of exhaust runner 6 ′ will change along its length as shown in FIG. 2B . It will start with the same 9 inch by 4 inch shape at the engine cylinder port, but as it travels towards the turbocharger adapter exhaust collector segment 8 ′ its shape will transform as depicted in FIGS. 2 and 2C . The goal is to have a similar cross section area along the exhaust flow path of exhaust runner 6 ′, but have the length and width dimension transition from 9 inches by 4 inches at a runner first end 6 ′- a to something close to 4 inches by 9 inches at a runner second end 6 ′- b . This will allow the creation of a cylindrical pocket that allows OC substrate 18 to slide in. The pocket does not need to be cylindrical, but the changing cross section of the exhaust runners 6 ′ is what allows a single OC substrate 18 to fit between the exhaust runner 6 ′ and the small flexible bellows 12 . Referring to FIG. 2C , the OC substrate 18 is likely to be a round metallic substrate approximately 18″ in diameter and 5″ thick. These sizes and substrate material composition will vary depending on system design. OC substrate 18 may slide all the way into either turbocharger adapter exhaust collector segment 8 ′ or into debris screen housing 10 ′, but is most likely to protrude partially into each. Other shapes of substrate and pockets to fit it in may not be cylindrical, but may be oval or rectangular. In this embodiment it is designed that the OC substrate 18 slides into a pocket created in turbocharger adapter exhaust collector segment 8 ′ and is retained in that pocket by debris screen housing 10 ′. In another embodiment, turbocharger adapter exhaust collector segment 8 ′ and debris screen housing 10 ′ may be combined into one assembly with OC substrate 18 sliding into this assembly from direction normal or close to normal to the axis of exhaust gas flow. This would require some kind of cover plate to be used to cover the pocket opening similar to the cover plates used in the Miratech V-Cat design. FIG. 3 is a side view of the prior art V-Cat system 80 patented and manufactured by Miratech. The V-Cat system 80 comprises four exhaust collector segments 82 which replace the three exhaust collector segments 4 and one turbocharger adapter exhaust collector segment 8 from FIG. 1 . In each exhaust collector segment 82 are four individual OC substrates to service the exhaust gases of four engine cylinders. A pair of OC substrates is captured on each side of a exhaust collector segment 82 by a cover 84 . Each exhaust collector segment 82 has four exhaust runners 86 similar to the exhaust runners 6 in FIG. 8 and FIG. 9 . It is a cover similar to cover 84 that could be used to retain a single OC substrate 18 into a combined turbocharger adapter exhaust collector segment 8 ′ and debris screen housing 10 ′. The second portion of the detailed description is most closely related to adjustable inlet guide vanes for improved emissions in EMD locomotives. FIG. 4 is a side view of a 16 cylinder EMD engine 2 . Turbocharger 15 is mounted to engine 2 . Variable inlet guide vane unit 6 is mounted to the compressor inlet of turbocharger 4 . Even with as much value and performance that the variable inlet guide vane units adds, FIG. 4 illustrates what a small and easy to package system the variable inlet guide vane unit is. No parts on the engine need to be replaced, only the intake pipe bringing in outside air to the turbocharger compressor inlet. On the other hand this unit may allow the simplification and cost reduction of the ECI conversion kit by eliminating the waste gate assembly the aftercooler diverter valve and its extra plumbing. FIG. 5 is an isometric view of the engine turbocharger 24 and the variable inlet guide vane unit 26 . In this view the guide vanes 28 are in the fully closed position, this leaves a small flow area 30 formed by the blade tips. In the prior art version of this device the valve was either fully open or fully closed, manipulation of this state was done by actuator 32 . New embodiments of this system will have actuator 32 upgraded to have variable positions. In one embodiment a 90 degree variable position actuator may be used and the fully closed position will not have the guide vanes 28 rotated so far that they touch. This now allows the vanes when rotated 90 to have traveled past neutral and be positioned at an angle to cause increased boost at notch 6 or act as a waste gate limiting turbine rpm at notch 8 . A further embodiment will have an actuator like the Delphi Smart Remote Actuator that has 120 degrees of travel. With this variable actuator, the guide vanes 28 can be rotated fully closed and still have the range to rotate 30 degrees past neutral well into the range where notch 6 boost is increased. FIG. 6 is an isometric view of a prior art inlet guide vane unit 26 ′ with the guide vanes 28 ′ partially open. The third portion of the detailed description is most closely related to a sonic and dual stage gas inlet valve that could also be used for continuous water injection. FIG. 7 is an isometric view of a standard ECI GIV assembly 40 . It illustrates the relationship between the GIV body 41 the valve seat insert 42 and the poppet valve 43 . In this view the poppet valve is in the fully extended position. This particular valve assembly is designed to inject natural gas into and EMD 2 Stroke natural gas engine on the compression stroke. It is possible to use this direct injection valve design and any embodiment of the current invention in any reciprocating engine using any gaseous fuel. This GIV could also be used for direct and continuous water injection. Gaseous fuel is supplied to the GIV at natural gas inlet 46 , secondary inlet 47 is where a supplemental water injector could be located. The mixed gaseous fuel and water mist could then exit the GIV into the combustion chamber at natural gas exit 48 FIG. 8 is a cross section view of the prior art GIV assembly 40 from FIG. 7 . FIG. 8 illustrates the poppet valve 43 and valve seat insert 42 when the poppet valve is fully extended. This valve is typical in construction to the exhaust and intake valves in most reciprocating piston engines. The valve seat area 44 is around 0.065″ wide and the valve seat angle is 60 degrees from the valve axis. The intent of this valve system is specifically to allow the most airflow to pass through it with the minimal amount of pressure drop during the time is has available to be open. There is minimal consideration as to what the characteristics the exiting airflow has and the pressure drop across these valves is typically under 2:1 for conventional engine intake and exhaust valves and up to 4:1 for the GIV units used on turbocharged EMD engines with a natural gas feed pressure of 80 psi. FIG. 9 is a cross section of the new poppet valve 43 ′ and valve seat insert 42 ′ design. Just the modification of these two parts converts ECI's standard GIV into a version that creates a sonic cone of injected gaseous fuel. The view on the left shows the valve in the closed position. Significantly different from FIG. 8 is that the flow cone angle is 50 degrees instead of 120. The valve seat angle is actually 25 degrees from the axis of poppet valve 43 ′ instead of 60 degrees in the prior art design. The cone angle could be more or less than and 50 degrees. The narrower this angle is, the further into the cylinder bore that the gaseous fuel travels before it impinges on the cylinder wall for improved mixing. FIG. 10A is a cross section view of a hydraulic actuator for the GIV assembly 40 with two discrete open positions. This view illustrates the GIV assembly 40 in the closed position. In this view the plunger 51 is inside of the plunger body 50 , and it is the plunger 51 that the hydraulic fluid pushes down on to open up the poppet valve 43 . These two parts are consistent with the standard prior art version of GIV assembly 40 . What is added in this embodiment is the plunger follower 52 , the plunger stop body 55 and the movable plunger stop 54 . FIG. 10B the GIV assembly 40 is in the full open position. The plunger 51 was forced down by the hydraulic fluid until it contacted the movable plunger stop 54 . The movable plunger stop 54 is resting on the top surface of the plunger stop body 55 . When the plunger 51 started to move in the downward direction, it contacted, pushed down on and moved the plunger follower 52 . The plunger follower 52 was in contact with the top of the poppet valve 43 and pushed it down also. All three parts continued to move downward until the plunger motion 51 was stopped as it contacted the movable plunger stop 54 . FIG. 10C illustrates the GIV assembly 40 in the partially open position. To stop the poppet valve 43 in this position, pressurized hydraulic fluid is fed into the plunger stop hydraulic port 53 . This pressurizes the plunger stop hydraulic cavity 57 and this pressure forces the movable plunger stop 54 to move up until it contacts the bottom of the plunger body 50 . With the movable plunger stop 54 in this position, the plunger 51 now travels a shorter distance before contacting the movable plunger stop 54 which will now limit the poppet valve 43 opening to a reduced stroke in the partially open position. The movable plunger stop 54 is able to keep the plunger 51 from moving it down because it has more surface area exposed to the hydraulic fluid pressure in the plunger stop hydraulic cavity 57 . This system could be designed to have more than one movable stop by multiplying certain features in this design. The standard way to operate an ECI low pressure direct injection EMD conversion is to have the valves stay open for set amount of time for each piston stroke. This time period is set by the amount of time available at high RPM to inject gas after the intake ports are closed. After this time period is set, the engine load is controlled by adjusting the gas supply pressure to the injectors. As the load and RPM decreases and less fuel is required, the supply pressure is decreased. It would be possible to maintain a constant pressure and then reduce the injection time as fuel demand decreased, but that may decrease the amount of air and fuel mixing because the high velocity fuel gas was injected for a shorter period of time. On a fuel system using standard poppet valves that achieve sonic flow at the valve periphery this would be a measurable effect. This is the primary advantage of the GIV with multiple valve stroke settings. It reduces the total amount of injector feed pressure, instead of reducing the pressure for all 8 throttle notches in a locomotive. The pressure could be reduced incrementally for Notches 7 and 6 , and then Notch 5 will have the GIV assembly 40 operate at reduced poppet valve 43 lift and a slightly longer valve open time because the RPM is now lower. From this point both the valve open time and gas supply pressure will be reduced incrementally down to the minimum flow needed at idle. The goal is to have the GIV fuel gas feed pressure remain high enough that good mixing is maintained, but balance that with manipulation of the valve open time to maximize the amount of time the high velocity injected gas is mixing with the air in the combustion chamber. As an example, instead of having a constant 80 milliseconds of injection time starting at a pressure of 300 and dropping to 100 at notch 1, now the highest 3 throttle notches will have an 80 ms injection time and pressure will drop to 250 in notch 6. At throttle notch 5 the injection time is raised to 115 ms, the poppet valve 43 lift is 40% of full open and the injector feed pressure is raised back to 300. By notch 3 the injection time has be lowered back to 80 ms and pressure feed pressure has only been reduce down to 275. By throttle notch 1, the pressure has been further reduced to 220. By ending at a 220 psi supply pressure instead of 100 psi, the exit velocity of the gas leaving the GIV should still be sonic. If it had dropped down to 100 psi, it would likely have become subsonic in the GIV. An interesting further use of this concept would be in large ship engines. Both 2 stroke and 4 stroke engines that are diesel pilot ignited would benefit from added swirl in the combustion chamber. Any number of these GIV's could be placed offset from the engine cylinder axis and tilted at an angle to induce a swirl to the air in the combustion chamber. If more than one supersonic GIV is used, they should have a similar angle in reference to the engine cylinder axis so that they induce swirl in the same direction. This swirl of air around the engine cylinder axis in the combustion chamber improves the combustion of the diesel pilot helping to lower PM or NOx emissions. This is because the swirl improves the air utilization during mixing controlled combustion as the surface of the diesel fuel jet is in contact with more air molecules than it would be if the air was stationary. Another interesting possibility will be the incorporation of sonic flow GIV's with an opposed piston engine. If only one sonic GIV was used per cylinder there would be the risk of the gas flow impinging on the opposite cylinder wall. This may or may not have detrimental effects such as a colder spot at the cylinder wall with possible lubrication or thermal stress issues. If cylinder wall impingement is to be avoided or for improved mixing, two of these sonic GIV's could be placed directly opposite of each other across the combustion chamber, in this case the two cone shape flows would collide in the middle of the chamber causing a great amount of turbulence and entraining significantly more intake air in the cylinder before the cold gases reach the cylinder walls. The fourth portion of this detailed description is most closely related to prechamber cooling sleeves including single and double pass variations. FIG. 11 is a cross section of a cylinder head 58 illustrating the placement of the prechamber 59 in relation to the cylinder head 58 and the piston 70 ′. The o-ring 61 at the top creates a cavity between the prechamber 59 outer surface and the cylinder head 58 pocket wall, this cavity is sealed at the bottom where the lower tapered section of the prechamber 59 is forced against the bottom of the cylinder head 58 pocket. This seal at the bottom is designed to resisted blow by of combustion gasses when the engine is operating so it will not have an issue keeping the prechamber coolant out of the engine cylinder. At the top of the prechamber 59 is the cooling fluid inlet 60 . Pressurized Cooling fluid is injected here and an internal passage brings the cooling fluid to an exit port on the outer surface of the prechamber below the o-ring 61 . The prechamber cooling fluid can be many different fluids including water, but in this preferred embodiment it would be engine oil to eliminate the need for return plumbing to a separate cooling fluid reservoir. In this embodiment, the cooling fluid is injected into a feed groove 67 around the prechamber 59 . This feed groove 67 acts as a manifold and helps distribute the cooling fluid around the entire circumference of the prechamber body 59 before it starts to flow through the narrow cavity between the prechamber body 59 and cylinder head 58 wall. This is considered the first pass of the coolant in a double pass prechamber cooling system. In this prechamber embodiment is a diesel injector, this prechamber configuration uses a micropilot of diesel fuel to start ignition. This invention would work in a similar fashion with a spark plug ignited prechamber with or without additional fuel being added to the prechamber 59 . Another embodiment not depicted could replace the single feed groove 67 around the prechamber body 59 with a spiral groove. The upper portion of the prechamber body 59 has a thicker wall section and in this area of the prechamber body a spiral groove could be cut into the outer surface of the prechamber. Possibly 10 to 15 turns, it would appear similar to an acme square thread except the eternal thread feature would be thin compared to the size of the passage. This spiral passage would slow the cooling fluid down allowing it more time to absorb heat from the prechamber body. The spiral groove feature could also give the cooling fluid more than twice the surface area to transfer heat. FIG. 12A is a close up cross section of the lower half of the prechamber body 59 . FIG. 12B is a detail view of FIG. 12A . Clearly visible is the prechamber nozzle 68 that slides over the prechamber body 59 from the bottom. The prechamber nozzle 68 is designed to contact the prechamber body 59 at two points with press fit pilots. There is a press fit pilot at the top of the prechamber nozzle 68 ; this pilot is in a low stress area and only seals against the cooling fluid going from the coolant first pass straight to the coolant collection groove. This is also the area that the prechamber nozzle 68 and the prechamber body 59 could be optionally welded together. If the prechamber body 59 upper half was equipped with an optional spiral coolant groove it would end before the optional weld area. The second contact point between the prechamber nozzle 68 and the prechamber body 59 is the press fit at the bottom of the prechamber nozzle 68 . This press fit is important as it seals the prechamber combustion area from the coolant cavity around the prechamber 59 . The thermal expansion stress from the prechamber body 59 heating up and the forces of combustion both enhance the sealing capacity. With or without the optional spiral cooling groove, the coolant first pass 64 starts at the point the cooling fluid is first injected at feed groove 67 on the exterior of the prechamber 59 and continues down the length of the outer surface of both the prechamber body 59 and prechamber nozzle 68 . As the cooling fluid moves along the coolant first pass 64 , it will be simultaneously absorbing heat from the prechamber 59 and prechamber nozzle 68 and transferring that excess heat to the cylinder head 58 surface. Just before the contact point where the prechamber nozzle 68 seals to the cylinder head 58 , there is a ring of radial coolant inlet holes 66 . These radial coolant inlet holes 66 are at the end of the coolant first pass 64 and the start of the cooling sleeve annulus 65 . These radial coolant inlet holes 66 are equally spaced small holes around the prechamber nozzle 68 and the pressure drop that the cooling fluid experiences as it transitions these radial coolant inlet holes 66 equalizes the flow around the perimeter of the prechamber nozzle 68 . This encourages the flow before and after the radial coolant inlet holes 66 to be more evenly distributed even if the thickness of the first and second coolant passes may vary slightly due to machining tolerances of the prechamber 59 or the head 58 . Once the cooling fluid enters the cooling sleeve annulus 65 , it will flow upwards around the outside of the prechamber 59 and the inside surface of the prechamber nozzle 68 . This cooling fluid ends up collecting in coolant return groove 62 and exiting prechamber 59 through coolant exit port 63 . This cavity for cooling sleeve annulus 65 should be thinner than that of coolant first pass 64 so that the cooling fluid travels faster and picks up less heat. The goal is to absorb only the amount of heat required out of the prechamber 59 body, but not so much that it can over heat the cooling fluid or over cool the prechamber body. When the coolant fluid is oil, overheating will result in the oil coking in this area and the corresponding overheating and failure of the prechamber due to lack of cooling fluid. A slower velocity along the outside of the prechamber nozzle 68 in the coolant first pass 64 will allow the cooling fluid to absorb more heat from the prechamber nozzle 68 and transfer it to the cylinder head 59 wall. There are three general goals of prechamber cooling; keeping the spark plug from overheating, keeping the prechamber nozzle 68 from getting hot enough to cause pre-ignition, while keeping the prechamber 59 inner combustion chamber walls hot enough to insure easy and rapid combustion internally. The coolant first pass around the top of the prechamber 59 is the area that will control spark plug temperature. The optional spiral cooling groove could enhance that cooling if needed. Prechamber nozzle 68 will get cooling from both coolant passes and will transfer some heat to the cylinder head 58 at its contact point. The heat transfer between contacting metal surfaces can be an order of magnitude less than the heat transfer through conduction of the base metal. Although the prechamber nozzle 68 to cylinder head contact 58 point is a cooling path, it is likely that significantly more heat from the nozzle is conducted up through the nozzle and absorbed by the cooling fluid that passes by two surfaces on the nozzle. The prechamber 59 wall around the prechamber combustion chamber is left as thick as possible to reduce the heat conduction rate and it is only cooled by a single pass of the cooling fluid. By the time the coolant has gotten to the end of the second pass in a double pass cooling sleeve, it may have gotten too hot to be effective. This will cause the lower part of the prechamber to be cooled more effectively and the cooling fluid could actually be over heated by the time it reaches the end of the cooling sleeve annulus 65 . In another embodiment a second set second radial inlet coolant holes 65 would function as bypass coolant holes that could allow some coolant to bypass the bottom of the prechamber body and start further up the coolant sleeve annulus 65 . These holes would allow some coolant to travel an abbreviated distance through the coolant sleeve annulus 65 of the nozzle 68 , therefor increasing the total amount of coolant fluid mass and decreasing the average temperature of the coolant that is used in last sections of the cooling sleeve annulus 65 of the double pass system. This also would slightly raise the temperature of the material at the start of the second pass as there would be less coolant going by. In another embodiment, the addition bypass coolant holes can be at multiple axial distances from the first radial cooling inlet holes 66 for even more even distribution of coolant temperature along the cooling sleeve annulus. Although nozzle 68 in this embodiment is pictured with an integrated cooling sleeve, alternate embodiments could have the cooling sleeve manufactured as a separate part from nozzle 68 with minimal change in the performance of the prechamber cooling system. FIG. 13A is a preferred embodiment of a prechamber 59 ′ for installation into a Detroit Diesel Series 60 diesel truck cylinder head 58 ′ instead of an EMD locomotive engine. In cylinder head 58 ′ there is a coolant cavity 92 that contains jacket water coolant for cooling the cylinder head. Typically this coolant will be a mixture of glycol and water. There are also two fuel return cavities 91 that would have been used to supply and return fuel for the diesel fuel injectors. In this embodiment those diesel injectors have been replaced by prechamber 59 ′. In this embodiment, it will be jacket water coolant instead of oil that will be used to cool the prechambers, and this coolant will have to be captured and returned to the engine cooling system. In this embodiment fuel return cavities 91 are used for the collection and transfer of prechamber cooling fluid out of the engine back to the jacket water cooling radiator system. FIG. 13B is a detail view of FIG. 13A and illustrates a prechamber cooling system that has a separate nozzle 68 ′ and cooling sleeve 93 . In this case the coolant is in a single pass configuration starting from the coolant cavity 92 , flowing through the radial coolant inlet holes 66 ′, up through the coolant sleeve annulus 65 ′ and exiting the prechamber 59 ′ through radial coolant exit holes 94 into fuel return cavity 91 ′. The fifth portion of this detailed description is most closely related to a variable compression ratio mechanism for an OPOC engine. This variable compression ratio system would operate on the outer pistons in the OPOC design. FIG. 14 is an exploded view of the VCR system. The outer wrist pin 71 slides into the piston 70 . There is an offset hole in the outer wrist pin 71 that the inner wrist pin (not shown) would be captured by. It is by rotating this outer wrist pin 71 around the inner wrist pin that the compression ratio is varied. The outer wrist pin 71 has a set of teeth machined into it and these teeth match the teeth cut into the rack gear 72 . The rack gear is free to slide axially along a bored hole in the piston 70 , as the rack gear 72 moves relative to the piston 70 it rotates the outer wrist pin 71 adjusting the compression ratio. The rack gear 72 has a female threads cut into it and the rack gear threaded insert 73 has a matching male thread on its OD that interfaces with the rack gear 72 internal thread. The rack gear threaded insert 73 is axially restrained in the piston 70 between a boss inside and the threaded insert retainer 74 that bolts to the back of the piston. It is the rack gear threaded insert 73 that positions the rack gear 72 axially in the piston 70 to set the compression ratio. The VCR actuator 75 is attached to the engine end cover and is fixed in place relative to the reciprocating motion of piston 70 . It has a male splined shaft 76 that interfaces with the female internal splines inside the rack gear threaded insert 73 . As the piston reciprocates inside its cylinder, the rack gear threaded insert 73 slides back and forth over the VCR actuator male splined shaft 76 . It is the VRC actuator that sets the compression ratio in each cylinder. In this embodiment there is an actuator for each cylinder in the engine. It would be possible to belt drive multiple spline rod assemblies with one actuator. In this design both the VCR actuator 75 male splined shaft 76 and the rack gear threaded insert 73 can be replaced as service items without disassembling the engine. The sixth portion of this detailed description is most closely related to grouped cylinder deactivation on prechamber ignited EMD 2 stroke engines. FIG. 15A illustrates the firing order of a 12 cylinder EMD 2-stroke engine. The top table is for firing all of the cylinders, the lower table illustrates just one bank firing. In the lower table the engine is broken down into two half engine banks with a top half and bottom half with either half being able to be deactivated leaving behind the rest of the engine to operate on cylinder to cylinder engine timing as even as the full engine was operating. If the top half of the engine operated by itself the firing order would be 1, 7, 3, 9, 2, 8 with degrees between firings 45, 75, 45, 75, 45, 75. Additionally, 9 of the cylinders could be deactivated leaving three cylinders still firing with 120 degree spacing if the three firing cylinders were all from the same quadrant of the engine, either 1, 2, 3 or 4, 5, 6 or 7, 8, 9, or 10, 11, 12. FIG. 15B is a similar set of engine firing order tables, except for a 16 cylinder engine. In this case, when operating either the top half or bottom half of the engine, the cylinder firing spacing is an even 45 degrees. When only 4 cylinders in one quadrant are operated the cylinder spacing is still even at 90 degrees. By being able to operate only 25% of the engine or 50% of the engine cylinders, the engine can be tuned to operate at more optimum air fuel ratios all the way down to idle and the prechambers can be turned off in banks with a simple isolation valve for each group of cylinders. Programming the ECU to not fire the GIV's in the deactivated cylinders is only a matter of software changes. Turning off the prechamber fuel feed to the opposing banks requires some additional hardware, but that can be as simple as two or four electrically controlled valves, one for the fuel supply to each bank of prechambers. As more advanced systems are proposed to get even lower emissions from these conversion systems, it will be likely that the prechamber supply pressure will not be constant. When the increased complexity of prechamber fuel pressure control is added, that would be a good time to institute this additional layer of control and hardware needed to turn on and off different prechamber feeds. For simplicity of control or in early deactivation systems, all of the spark plugs can be fired, even those in deactivated cylinders. In more advanced systems it is likely that the spark plugs would not be fired when the cylinders are deactivated to extend the spark plug service lives. When turning on and off the prechamber fuel supply, it may be beneficial to turn the spark plugs on a few cycles early, and when turning off the prechamber fuel supply it would be beneficial to fire the spark plugs a few cycles later. FIGS. 16A, 17, 18A-18C, 19A-19C, 20, 21, and 22A-22B illustrate a new prechamber nozzle 69 ″ design that uses 6 radial located groups of three 0.050 TJI jets 96 to replace one set of 6 individual larger orifice jets. These three TJI jets 96 in each group converge together at a point some distance, possibly ¾ of an inch, away from the nozzle. This new concept is likely to have both the quenching effect and good combustion chamber penetration. Because the three jets converge they will penetrate further into the combustion chamber similar to a larger single jet. It is likely that the efficiency of the group of jets with regard to penetration would be slightly less than a single larger jet of either the same effective area or combined flow rate. This seeming negative could have a silver lining in that it has the needed penetration, all of the burning gases quenched and at the same time a more concentrated pocket of partially burned combustion radicals to stimulate very rapid combustion throughout the chamber once ignition is started. FIG. 16A the Nozzle 69 ″ is illustrated with groups of 3 TJI jets 96 converging into a combined jet. In practice good results could be attained with only two TJI jets 96 in each group or four or more if needed. The concept is to have as many orifice jets as needed converge into a single flow to achieve the required penetration and local combustion intensity. In another embodiment, it is proposed to have some or all of the TJI jets 96 be offset from the centerline axis of nozzle 69 ″. If a set of jets enters the nozzle throat with the same offset they will give the flow entering the prechamber through the nozzle throat 97 a rotational flow along with the axial flow component. This swirling effect will have multiple benefits. The first and most intuitive benefit of the swirling flow be improved mixing at the top of the prechamber combustion chamber reducing the stratification of the air and fuel around the spark plug. Another non-intuitive benefit of the swirling flow entering the prechamber combustion chamber will be the larger effective volume of the flow as it has an axial velocity component and a rotational velocity component. This will require an increase of the mixing throat 97 diameter to have the same effective pressure drop and flow accelerating capability as a smaller throat diameter with a purely axial flow. On the other hand, after combustion when the rotational flow component is much less, the pressure drop across the throat will be less insuring more pressure drop across the jet orifices and higher velocity, mass flow and penetration of the jets. Essentially the mixing throat 97 will now effectively be less restrictive in the most beneficial direction. A potential issue being explored with multiple small jets in a prechamber nozzle designed for Turbulent Jet ignition is that complete quenching of the burning gasses as they exit may sometimes cause a misfire. At high loads where the in cylinder main chamber temperatures are higher because the gasses have less time to transfer heat to the surrounding metal, the TJI prechambers may exhibit stable combustion. Proposed is to have TJI jets in both a smaller diameter and a larger diameter. FIG. 16B illustrates one embodiment with groups of smaller diameter TJI jets 96 around the nozzle and then one larger diameter axial TJI jet 98 in the center. In this case the intent is that the axial TJI jet 98 is large enough in diameter to start combustion on its own, and the smaller TJI jets 96 discharged quenched air and fuel forming areas of ready to burn pockets. When the main combustion event is initiated by the larger torch nozzles, these pockets will subsequently ignite providing more rapid heat release. Pure TJI with all quenched jets would offer even higher heat release rates by delaying combustion even further, but could suffer from misfire. This system would overcome some misfire potential at some difficult engine operating points such as very low power. Also in some engines pure TJI may have heat release rates that are too rapid. This system could be used to mitigate that giving some of the benefit of TJI without the excessive heat release rate. In another embodiment, is to the single axial TJI jet 98 is eliminated and one of the quenched TJI jets 96 in one or several of the radial groups has a larger diameter so as to lose the quenching effect and act as a torch jet. In another embodiment, the axial jet 98 could be replaced by a set of group of smaller diameter axial jets 98 similar to the radial groupings of TJI jets 96 . These axial jets 98 could remain parallel to each other in the axial direction of each be angled slightly off axis to converge. A second significant benefit of the axial jets 98 is to improve mixing internal to the prechamber. By adjusting the number and diameter of these axial jets 98 both the mixing benefit and the torch effect can be optimized. It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages.

A prechamber assembly includes a cylinder head including a coolant cavity, a prechamber body located within the cylinder head, the prechamber body including a nozzle, and an annular sleeve radially surrounding a portion of the prechamber body. The sleeve includes a plurality of coolant inlet holes. A portion of the prechamber body is radially spaced from the sleeve to form a coolant sleeve annulus extending along a length of the prechamber body above the coolant inlet holes. The coolant cavity and the coolant sleeve annulus are in fluid communication through the plurality of coolant inlet holes.

[0001] This non-provisional application claims the benefit of U.S. Provisional Application No. 60/357,850, entitled “Zooming Interfaces For Sensemaking, Visualization, and Navigation” which was filed on Feb. 21, 2002, and is hereby incorporated by reference in its entirety. RELATED APPLICATIONS [0002] The following related U.S. patent applications are hereby incorporated herein by reference in their entirety: [0003] U.S. patent application Ser. No. ______, Docket No. D/A1311, entitled “System and Method for Interaction of Graphical Objects on a Computer Controlled System”; [0004] U.S. patent application Ser. No. ______, Docket No. D/A1311Q, entitled “System and Method for Moving Graphical Objects on a Computer Controlled System”; [0005] U.S. patent application Ser. No. ______, Docket No. D/A1687, Attorney Docket No. 111743, entitled “Method and System for Incrementally Changing Text Representation”; [0006] U.S. patent application Ser. No. ______, Docket No. D/A1687Q, Attorney Docket No. 115122, entitled “Method and System for Incrementally Changing Text Representation”; [0007] U.S. patent application Ser. No. ______, Docket No. D/A1309, Attorney Docket No. 112463, entitled “Methods and Systems for Navigating a Workspace”; and [0008] U.S. patent application Ser. No. ______, Docket No. D/A1310, Attorney Docket No.112467, entitled “Methods and Systems for Indicating Invisible Contents of Workspace”. BACKGROUND OF THE INVENTION [0009] 1. Field of Invention [0010] This invention relates to methods and systems for interactive classification of object. [0011] 2. Description of Related Art [0012] “Sensemaking” is a process of gathering, understanding, and using information for a purpose. Sensemaking tasks often involve searching for relevant documents and then extracting and reformulating information so that the information can be better utilized. A sensemaker gathers information, identifies and extracts portions of the information, organizes such portions for efficient use, and ultimately incorporates the information in a work product with the required logical and rhetorical structure. [0013] A common part of many sensemaking tasks is organizing “factoids” or other units of information, or objects, into related groups. Objects may be any form, such as simple text or a list of items. The difficulty of organizing objects depends on several practical factors, including the number of objects to be organized and the efficiency of the operations for finding, reading and manipulating the objects. [0014] A key factor that influences the efficiency of an organizing task on a display, such as a computer display, is the size of a viewed space in a workspace. For a classification task on a display too small to show all of the objects, some objects are necessarily out of sight, so that a sensemaker must take additional steps and often use more time in locating and manipulating objects. In this case, search operations generally require not only scanning with the eyes, but also navigation with a pointer using panning, scrolling, and zooming. Such operations, which bring objects into the viewed space, significantly add to the time required in comparison with larger displays. The overhead of panning or scrolling can also adversely affect overall performance by distracting the sensemaker with extra steps and by requiring the sensemaker to remember things while navigating between objects. [0015] Estes teaches that there are two primary types of models used to explain human classification behavior: exemplar-based models and rule-based models (Estes, W. K. (1994) Classification and Cognition. New York: Oxford University Press, pp 33-87). These two models of classification also correspond well with how humans organize objects into groups using a workspace such as a computer display. [0016] In organizing objects into groups in a workspace, the rule-based classification tends to be formal. In this instance, a set of categories is determined, and explicit membership criteria are established for each of the categories by rules. To classify an object, a sensemaker checks the rules for each category and adds an object to whichever category the object satisfies the rules. Classifying an object amounts to adding the object to a “bucket” containing the objects that satisfy the membership criteria. [0017] Determining or defining a category requires upfront work. A sensemaker may have to assign or allocate a place for the new category, determine the membership criteria, add the object to the category, and write down the membership criteria in a title or other visible label. Once this is done, however, future assignments of objects to this category go faster because the sensemaker need only check the label and then “drop” appropriate objects into the category. [0018] With respect to computer systems, the membership criteria often take the form of a title or label on a window or folder. For example, e-mail systems, such as Eudora® and Microsoft® Outlook®, provide hierarchies of named mail folders for classifying messages. Storing an email message into an appropriate folder is an example of classifying an object. A key feature of interactive rule-based classification is that the decision about how to classify an object requires reading the membership criteria (in the form of titles or folder names), but generally does not require reading the previously classified objects (such as the email messages already in the folder). [0019] Organizing objects into groups in a workspace using exemplar-based classification, on the other hand, is more tentative and informal. To classify an object, one must compare the object with the examples in an informal category or cluster in order to determine whether the object fits. Classifying an object amounts to placing the object in or near a cluster of similar objects. [0020] Creating a cluster or implicit category requires less upfront work than creating a formal, or explicit category, but has greater overhead for future classifications. To set up a new cluster, a sensemaker simply places a new object in some uncrowded region of the workspace, possibly near other clusters or categories that seem somewhat related. No label or membership criteria are supplied. Future classifications are somewhat more tedious than in the case of explicit categories because the sensemaker needs to examine members of clusters in order to determine where to place new objects. Unless the sensemaker remembers tentative abstractions for a cluster, there is no shortcut for membership determination by checking a label or rule. [0021] In a workspace, exemplar-based classification amounts to visual clustering. There are no explicit titles or rules for membership in a cluster. The boundaries of the clusters can be somewhat more tentative and ambiguous, especially when two clusters are near each other. The decision about how to classify an object requires reading or scanning other objects to detect similarity, and then locating the new object near the other objects that the new object best matches. [0022] In interactive sensemaking workspaces, two types of overviews may be available: structural overviews that show a list of categories to which objects may be classified, and special overviews that show positional relationships of objects in the workspace. [0023] Structural overviews are well suited for rule-based classification where the formal categories correspond to labels in an outline. FIG. 1 is an example of structural overviews. An interface, such as a drag-and-drop interface, makes the process of adding objects to a category convenient. Structural overviews can incorporate nesting, yielding hierarchical trees of categories. [0024] However, structural overviews provide no support for exemplar-based classification because the structural overviews show the labels of formal categories, but nothing about the informal categories. [0025] Spatial overviews provide a rendering of the workspace. Such overviews can be allocated permanently or transiently at a portion of the display space, while most of the sensemaker's work is done in a focus of the workspace. Using such spatial overviews, formal categories and informal categories can be both shown at a reduced scale. [0026] However, because of the reduced scale, the sensemaker may have to zoom in the workspace in order or put a desired section of the workspace in focus, to recognize and understand the contents of objects for classification. [0027] [0027]FIG. 2 shows an example of a workspace, a viewed space, an overview and objects. In FIG. 2, a focus 100 includes objects 110 - 130 . An overview 140 provides a rendering of an entire workspace 150 . A frame 160 indicates a currently viewed space within the workspace 150 . An object may have one or more sub-objects within, which may form a multi-level object. A sensemaker can bring any part of the workspace into the viewed space by clicking or dragging on a region in the overview 140 or scrolling the viewed space. [0028] U.S. Pat. No. 6,243,093 to Czerwinski et al. discloses a system for spatially organizing stored web pages that automatically highlights similar web pages during organization and retrieval tasks. When the user drags or clicks on a web page, similarity metrics between the dragged or clicked web page and other stored web pages in a single-level spatial workspace are computed and web pages with such similarity are highlighted to the sensemaker. This system computes similarity metrics between items in a spatial workspace and displays this similarity to the user. However, this system does not indicate how objects are similar, but rather simply indicates numeric scores for the similarity. Similarly, this system does not use automatic similarity indicators for labeled hierarchical organizations rather than large single level spaces. [0029] Similar techniques have also been applied to information retrieval in large document collections, such as the Web. One such technique described by Hearst (Hearst, 1995, TileBars: Visualization of Term Distribution Information in Full Text Information Access, Proceedings of CHI '95. p. 59-66), called TileBars, creates simple colored rectangles to represent the pages in a set of documents. In this technique, the intensity of the fill color of these rectangles signifies the number of query matches on the specified page. A related technique by Woodruff et al. (Woodruff, Faulring, Rosenholtz, Morrison, & Pirolli, 2001, Using Thumbnails to Search the Web, Conference Proceedings of CHI 2001, Vol. 3, Issue 1, p. 198-205, 552) enhances standard web page thumbnails with enlarged text labels. These enlarged labels indicate the location and frequency of query terms, combining the benefits of traditional thumbnails with the benefits of simple text summaries. Nevertheless, both these techniques have been applied only to static one-dimensional documents. These techniques do not extend them to dynamic documents with multiple dimensions. SUMMARY OF THE INVENTION [0030] The interactive classification technique according to the invention facilitates classification of a new object added to a workspace. In a workspace for sensemaking, objects often include text segments. In addition, objects may be made multi-level, that is, objects may have sub-objects within. Sensemakers tend to use a mixture of rule-based and exemplar-based strategies for classification tasks when working in such a workspace. A mixture of strategies enables sensemakers to create tentative clusters when the sensemakers are not yet sure of the criteria, and to create efficient rule-based categories, as the criteria are determined or established. [0031] To increase the efficiency and ease of locating and understanding objects in a workspace, objects may be interactively classified and put together based on the objects' similarity. [0032] Therefore, an object of the invention is to provide methods and systems for interactive classification of objects. In various exemplary embodiments, the method includes receiving an instruction to place a new object into a workspace, determining a similarity of the new object to an existing object, category, or cluster, and providing a visual indication of the similar words in both the new object and an existing object, cluster, or category. The visual indication may also reflect the degree to which the new object is similar to the existing object, cluster, or category. The method may also provide an indication of a place for manual placement of the new object. The method may also include providing a view of a place with objects having the similarity. [0033] Therefore, the methods and systems according to this invention can facilitate classification of objects in a workspace and thus facilitate the sensemaker's understanding of the objects and the workspace. BRIEF DESCRIPTION OF THE DRAWINGS [0034] Various exemplary embodiments of the systems and methods according to this invention will be described in detail, with reference to the following figures, wherein: [0035] [0035]FIG. 1 is an exemplary structural overview; [0036] [0036]FIG. 2 is an exemplary workspace including a current view of objects and an overview; [0037] [0037]FIG. 3 shows a first exemplary embodiment according to this invention in which objects in a workspace are highlighted based on a similarity metric; [0038] [0038]FIG. 4 shows a second exemplary embodiment according to this invention in which terms are enlarged; [0039] [0039]FIG. 5 is an exemplary block diagram of an interactive classification system according to this invention; and [0040] [0040]FIGS. 6 and 7 show a flowchart illustrating an exemplary embodiment of a method of interactive classification according to this invention. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS [0041] Interactive classification methods according to this invention can provide a way to automatically classify and/or place a new object, or provide assistance for manual classification and/or placement of objects in a workspace, based on similarity of the objects. In various exemplary embodiments, the methods according to this invention facilitate interactive classification with improved performance, such as speed and/or ease. [0042] Various aspects of this present invention may be incorporated in a system, such as the systems disclosed in a co-pending, co-assigned U.S. patent application Ser. No. ______, Docket No. D/A1311, entitled “System and Method for Interaction of Graphical Objects on A Computer Controlled System,” which is incorporated herein by reference in its entirety. [0043] For interactive classification of an object, a similarity metric may be determined for identifying which objects are more similar, and a key element identifier may be used for determining which of various elements, such as words, in an object contributes most to the judgment of similarity. For example, similarity may be determined as follows. [0044] First, an object may be divided into elements, such as, individual words. Then, the words are reduced to the smallest form, or stems, so that variant forms of each individual word become identical. Stem or term frequencies in the object (“document”) and in the collection of objects (“corpus”) are then computed. A combined weight reflecting the relative frequencies of the terms in the document and corpus is computed using a term frequency inverse document frequency (TFIDF) or similar scheme. [0045] A similarity matcher may be used in conjunction with other parts of a sensemaking tool to give a sensemaker more useful feedback and to facilitate an interactive classification task. For example, related objects and groups in the workspace and overview may be highlighted when a new object is selected for classification. For example, as shown in FIG. 2, in an overview 200 , objects 210 that have a similarity with the new object are highlighted for an indication to the sensemaker. Such highlighting may draw the sensemaker's attention to the most likely classification opportunities, depending on the selectivity of the similarity computation. Alternatively or additionally, the system may automatically pan into a view that includes a best-matching object, cluster, or category for the new object. Further, a shortcut operation, such as a gesture or button on the object, may be provided that instructs the system to classify the object, without the sensemaker needing to perform a drag-and-drop operation. In many cases, combining such feedback with what the sensemaker already knows about the collection may be enough to facilitate complete classification. [0046] In addition to determining a similarity metric for individual objects, a similarity score for a group, such as a cluster or explicit category, may be determined. [0047] One approach is to take all of the objects in a group and treat the objects as if the objects constitute a single document. Assuming that the term frequencies are normalized for the document, this approach may essentially create an average document to which the unclassified object may be compared. [0048] Another approach is to take a score of the best matching object in a group as a representative of the group. This approach may tend to emphasize clusters where at least some of the objects have a very high similarity to the unclassified object. [0049] Another approach is to determine a weighted intermediate score between the average match and the best match for a group. For example, a composite score may be determined from the average similarity and the best similarity for the group. [0050] The methods for computing a similarity score for a group as described above may not take into account any explicit rules for formal categories. In classification tasks, the “rules” may be in the form of labels rather than executable rules. Various methods are contemplated for including the content of the label of a group in a similarity matching process, as further described below. [0051] One approach is to simply match the label, ignoring the content of the objects in the group. Another approach is to append one or more copies of the group label to the individual objects in order to enhance the contribution of the label terms in the computation of a similarity score for each object. This approach can be combined with the methods described above. [0052] In the case of informal categories, two exemplary approaches are computing similarities only for individual objects and computing aggregate similarities. The latter approach may require determining which objects are in a cluster. Two kinds of information may be used to in determining cluster membership: the coordinates of the objects in the workspace and the similarity of the objects. Such information may be combined in various ways. Once a cluster is identified, the aggregate scoring methods described above for groups may be used. [0053] One approach to displaying similarity information, either in an overview or in a detailed workspace, is to use a similarity metric to determine which regions to highlight. This approach may be similar to a technique disclosed in a copending, co-assigned U.S. patent application Ser. No. _______, Docket No. D/A1310, Attorney Docket No. 112467, entitled “Methods and System for Indicating Invisible Contents of Workspace”, incorporated herein by reference in its entirety. Various visual effects may be used to convey information, such as color and intensity. [0054] For example, only matches above a predetermined threshold may be included in the visual transfer functions using, for example, one form of highlighting to indicate matches for which there is a very high degree of similarity and another form of highlighting to indicate matches with a significant, but more moderate degree of similarity. [0055] An issue with just using similarity scores for classification is that the scores may be non-specific. An object about, for example, “driving tips” might match one group of objects on the basis of one criterion (e.g., “weather rules” or rules mentioning “fog”) and another group of objects on the basis of another criterion (e.g., “speed rules” or rules mentioning “speed”). If the similarity scores for the two groups are about equal, then highlighting by itself does not convey information for discriminating between the two groups. [0056] An alternative to simple highlighting based on the similarity score is to augment the display of matching objects with a specific indicator of the reason for the match, such as the particular elements that contribute most to the similarity score. In the above-described examples, the indicator may be, for example, temporarily superimposing the most important matching or similarity term(s) in a different color on each object or group. [0057] This approach of enhancing the display of similar objects and groups compensates to some degree for the inevitable irregularities in similarity matching scores and provides more specific signals to the sensemaker about which groups or objects are similar in ways that matter. As shown in FIG. 4, where more than one category is similar, specific terms 300 like “fog” and “speed” may be enlarged to convey more information to the sensemaker. Other indication of terms is contemplated as well, such as highlighting, flashing, and the like. [0058] When similarity signals are displayed, the indication should be clear as to which objects the similarity signals refer. One approach is to display similarity signals, such as similarity terms, within the bounds of the matched object. Another approach is to provide call-outs or labels on arrows that indicate that a similarity signal refers to a particular object. [0059] As new objects are classified, the similarity signals may need to be refreshed to make use of the information in the objects. That is, signals from a previous match may need to disappear. One approach is to make similarity signals transient so that the signals may stay in view only during a specific matching operation. Another approach is to make the signals slowly fade from the display, or to make the signals disappear in response to a sensemaker's request. It will be appreciated that many other approaches are possible. [0060] The strongest matches may not be close enough to be displayed simultaneously. The system may automatically bring into view the objects or groups with the greatest degree of match. Furthermore, the system may automatically pan, scroll, or zoom based on the similarity scores of the groups and/or objects. [0061] Should the sensemaker desire to return to the workspace in which the sensemaker was working before such panning, scrolling or zooming, controls enabling the sensemaker to go forward or backward, for example, by forward and backward buttons, may be provided to help the sensemaker tour the matching groups and/or objects. An example of a technique used to go forward or backward is described in a co-pending, co-assigned U.S. patent application Ser. No. ______, Docket No. D/A1309, Attorney Docket No. 112463, entitled “Method and System for Navigating A Workspace,” which is incorporated herein by reference in its entirety. [0062] Another approach is to use “pop-up signals” such that the similarity signal appears on the objects when an input is received. For example, as the sensemaker moves a cursor, a mouse pointer or the like over an overview or over the workspace, annotations about similarity may transiently appear. [0063] Moreover, when a new object to be classified has a degree of match with nested groups at several levels of a hierarchy, the signal may need to differentiate among the levels and may indicate the level where the similarity is the greatest. [0064] Similarity may be shown either to individual objects of a group or to a group as a whole. Generally, there may not be enough space to display both. The amount of space available can be used to govern the choice. When there is insufficient space to indicate the similarity to each of the separate objects in a group, the display may be limited to the similarity terms for the group as a whole. In the case of clusters, a determination of the elements that are in the cluster may be required. [0065] Drag-and-drop interfaces to an overview may speed up the classification of a new object. Using the drag-and-drop interfaces, when the user places a new object, the system may automatically indicate one or more positions to which the user may place the new object based on the similarity between the new object and the objects that already exist in the workspace. The description of how the drag-and-drop technique works is omitted here since any existing or hereafter developed drag-and-drop technique may be used. It should be understood that any other known or hereafter developed technique for introducing an object to the workspace may be used. [0066] [0066]FIG. 5 shows a block diagram of an interactive classification system 500 according to the invention. The interactive classification system 500 includes a controller 510 , a memory 520 , an input/output (I/O) interface 530 , a new object detection circuit 540 , a similarity signal determination circuit 550 , a cluster detecting circuit 560 , a representation circuit 570 , a placement assisting circuit 580 , and a visual effect circuit 590 , which are connected to each other via a communication link 600 . To the I/O interface 530 , a data sink 610 , a data source 620 and a user input device 630 are connected via communication links 611 , 621 and 631 , respectively. [0067] The controller 510 controls the general data flow between other components of the interactive classification system 500 . The memory 520 may serve as a buffer for information coming into or going out of the system 500 , may store any necessary programs and/or data for implementing the functions of the interactive classification system 500 , and/or may store data, such as history data of interactions, at various stages of processing. [0068] Alterable portions of the memory 520 may be, in various exemplary embodiments, implemented using static or dynamic RAM. However, the memory 520 can also be implemented using a floppy disk and disk drive, a writable or rewritable optical disk and disk drive, a hard drive, flash memory or the like. [0069] The I/O interface 530 provides a connection between the interactive classification system 500 and the data sink 610 , the data source 620 , and the user input device 630 , via the communication links 611 , 621 , and 631 , respectively. [0070] The new object detection circuit 540 receives an instruction from the user to place a new object. To provide the instruction, the user may use a drag-and-drop technique, for example, to place a new object. [0071] The similarity determination circuit 550 determines the similarity of a new object to the objects in the workspace. Such determination may be done by, for example, determining a similarity metric for identifying which object(s) is most similar and determining which of the elements (e.g., words) in the new object most contributed to the judgment of similarity. Such similarity metric may be calculated by breaking an object into elements, such as words, reducing the elements to stems, and computing term (stem) frequencies in the object and in the collection of objects. [0072] The cluster detecting circuit 560 determines a cluster or a group of objects in the workspace. Determination of a cluster or a group may be done by identifying coordinates of the objects in the workspace and/or the similarity of the cluster or the group. [0073] The similarity representation circuit 570 represents the indication of similarity of the new object to the existing objects by, for example, highlighting the most similar categories or objects. In addition, the similarity representation circuit 570 may transiently pop up a similarity signal based on an input from a user interface, such as moving a cursor onto an interface using a mouse or the like. The representation circuit 570 may also represent elements in objects that are most similar to the new object and refresh the similarity signal for previous matches by using, for example, fading operations. [0074] The placement assisting circuit 580 provides assistance to the sensemaker for placement of the new object, including, for example, highlighting a possible space for placement of the object based on the similarity metric or providing an arrow in the overview. [0075] The visual effect circuit 590 provides visual effects after placement of the new object. Such visual effects may include scrolling, panning, and/or zooming in the workspace. [0076] The data sink 610 can be any known or later-developed device that is capable of outputting or storing the processed media data generated using the systems and methods according to the invention, such as a display device, a printer, a copier or other image forming device, a facsimile device, a memory or the like. In the exemplary embodiments, the data sink 610 is assumed to be a display device, such as a computer monitor or the like, and is connected to the interactive classification system 500 over the communications link 611 . [0077] The data source 620 can be a locally or remotely located computer sharing data, a scanner, or any other known or later-developed device that is capable of generating electronic media, such as a document. The data source 620 may also be a data carrier, such as a magnetic storage disc, CD-ROM or the like. Similarly, the data source 620 can be any suitable device that stores and/or transmits electronic media data, such as a client or a server of a network, or the Internet, and especially the World Wide Web, and news groups. The data source 620 may also be any known or later developed device that broadcasts media data. [0078] The electronic media data of the data source 620 may be text, a scanned image of a physical document, media data created electronically using any software, such as word processing software, or media data created using any known or later developed programming language and/or computer software program, the contents of an application window on a sensemaker's desktop, e.g., the toolbars, windows decorations, a spreadsheet shown in a spreadsheet program, or any other known or later-developed data source. [0079] The user input device 630 may be any known or later-developed device that is capable of imputing data and/or control commands to the interactive classification system 500 via the communication link 631 . The user input device may include one or more of a keyboard, a mouse, a touch pen, a touch pad, a pointing device, or the like. [0080] The communication links 600 , 611 , 621 and 631 can each be any known or later-developed device or system for connecting between the controller 510 , the memory 520 , the I/O interface 530 , the new object detection circuit 540 , the similarity determination circuit 550 , the cluster detecting circuit 560 , and the representation circuit 570 , the placement assisting circuit 580 , and the visual effect circuit 590 , to the data sink 610 , the data source 620 , and the user input device 630 , respectively, to the interactive classification system 500 , including a direct cable connection, a connection over a wide area network or local area network, a connection over an intranet, a connection over the Internet, or a connection over any other distributed processing network system. Further, it should be appreciated that the communication links 600 , 611 , 621 and 631 can be, a wired wireless or optical connection to a network. The network can be a local area network, a wide area network, an intranet, the Internet, or any other known or later-developed other distributed processing and storage network. [0081] [0081]FIGS. 6 and 7 show a flowchart of an exemplary embodiment of a method of indicating objects according to the invention. [0082] The process starts at step S 1000 and continues to step S 1010 . In step S 1010 , a new object is introduced to an overview of a workspace, and the process continues to step S 1020 . In step S 1020 , a determination is made as to whether clusters should be determined. If so, the process continues to step S 1030 ; otherwise the process jumps to step S 1040 . [0083] In step S 1030 , clusters are determined, and the process continues to step S 1040 . In step S 1040 , similarity of the objects already existing in the work space is determined with respect to the new object. Then, the process continues to step S 1050 . [0084] In step S 1050 , a determination is made as to whether a threshold on the similarity should be used. If so, the process continues to step S 1060 ; otherwise, the process jumps to step S 1070 . In step S 1060 , the objects having similarity below the threshold are discarded, and the process continues to step S 1070 . [0085] In step S 1070 , a determination is made as to whether there are any objects with the similarity. If so, the process continues to step S 1080 ; otherwise, the process jumps to step S 1150 , at which the process ends. [0086] In step S 1080 , similarity indicators are displayed. The similarity indicators may include similarity metrics and highlighting terms used for determining the similarity, for example. In step S 1090 , a determination is made as to whether a shortcut should be displayed to assist classification of objects. If so, the process continues to step S 1100 ; otherwise, the process jumps to step S 1110 . [0087] In step S 1100 , the shortcut is displayed, and the process continues to step S 1110 . In step S 1110 , a determination is made as to whether a possible location(s) for placing of the new object should be indicated. If so, the process continues to step S 1120 ; otherwise, the process jumps to step S 1130 . [0088] In step S 1120 , a possible location(s) for placing of the new object is indicated, and the process continues to step S 1130 . In step S 1130 , a determination is made as to whether a viewed space should be moved to the similar object(s). If so, the process continues to step S 1140 ; otherwise the process jumps to step S 1150 . At step S 1140 , a viewed space is moved to the similar object(s). Then, the process continues to step S 1150 . The process ends at step S 1150 . [0089] It is apparent that these steps are described in above order for illustration purpose, and in various exemplary embodiments, the determination of similarity of objects, placement of the new object and the like described above, may be performed in different order and/or with additional or fewer steps. Furthermore, the invention is not limited to the above described methods and system. Those skilled in the art would understand that many different modifications are possible without departing from the scope of the invention. [0090] Additionally, those skilled in the art will recognize many applications for the present invention include, but not limited to, document display devices, such as browser devices, that display applications of a personal computer, handheld devices, and the like. In short, the invention has application to any known or later-developed systems and devices capable of interactively classifying objects in a workspace. [0091] In the exemplary embodiments outlined above, the interactive classification system 500 can be implemented using a programmed general-purpose computer. However, the interactive classification system 500 can also be implemented using a special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an ASIC or other integrated circuit, a digital signal processor, a hardware electronic or logic circuit, such as a discrete element circuit, a programmable logic device, such as PLD, PLA, FPGA or PAL, or the like. In general, any device, capable of implementing a finite state machine that is in turn capable of implementing the flowchart shown in FIGS. 8 - 10 can be used to implement the interactive classification system 500 . [0092] Each of the circuits or routines and elements of the various exemplary embodiments of the interactive classification system 500 outlined above can be implemented as portions of a suitable programmed general purpose computer. Alternatively, each of the circuits and elements of the various exemplary embodiments of the interactive classification system 500 outlined above can be implemented as physically distinct hardware circuits within an ASIC, or using FPGA, a PDL, a PLA or a PAL, or using discrete logic elements or discrete circuit elements. The particular form each of the circuits and elements of the various exemplary embodiments of the interactive classification system 500 outlined above will take is a design choice and will be obvious and predicable to those skilled in the art. [0093] Moreover, the exemplary embodiments of the interactive classification system 500 outlined above and/or each of the various circuits and elements discussed above can each be implemented as software routines, managers or objects executing on a programmed general purpose computer, a special purpose computer, a microprocessor or the like. In this case, the various exemplary embodiments of the interactive classification system 500 and/or each or the various circuits and elements discussed above can each be implemented as one or more routines embedded in the communication network, as a resource residing on a server, or the like. The various exemplary embodiments of the interactive classification system 500 and the various circuits and elements discussed above can also be implemented by physically incorporating the interactive classification system 500 into a software and/or hardware system, such as the hardware and software system of a web server or a client device. [0094] While this invention has been described in conjunction with the exemplary embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.

Methods and systems provide a computational assistance for interactive classification that compensates for the small size of computer screens and accelerates classification tasks. Similarity indicators reduce manual search by enabling information objects to “call out” automatically to encourage a sensemaker to place related items nearby. Similarity terms signal which groups or objects match and why they match. Using these techniques, an interactive classification tool can focus a sensemaker's attention, move things into view automatically, and provide shortcuts for automatic classification. These techniques speed up classification for rule-based classification, example-based classification, and mixed strategies and have the potential for application in a wide variety of sensemaking tools.

TECHNICAL FIELD [0001] This disclosure relates generally to signal acquisition systems and, more particularly, to a system, apparatus and method for reducing measurement errors due to, for example, probe tip loading of a device under test. BACKGROUND [0002] Typical probes used for signal acquisition and analysis devices such as oscilloscopes and the like have an impedance associated with them which varies with frequency. As the bandwidth of test and measurement instruments and probe system become wider the effects of probe tip loading of non-flat through responses becomes more significant than in past systems. [0003] U.S. Pat. No. 6,725,170 entitled “Smart probe apparatus and method for automatic self-adjustment of an oscilloscope's bandwidth” to Barton Hickman, owned by Tektronix, Inc. and incorporated herein by reference, discloses storing S-parameters of a probe so that equalization filters can be computed when a probe is connected to different input channels of different types of test and measurement instruments. These equalization filters, however, are designed for device under test (DUT) source impedance of 50 ohms. What is needed is an equalization filter that can be calculated using the nominal source impedance of the DUT. Using the prior methods, if the source impedance of the DUT is not 50 ohms, then the acquired waveform received via a probe loading such a circuit may not accurately represent the voltage of the circuit prior to the introduction of the probe. SUMMARY [0004] Certain embodiments of the disclosed technology include a test and measurement system including a test and measurement instrument, a probe connected to the test and measurement instrument, a device under test connected to the probe, at least one memory configured to store parameters for characterizing the probe, a user interface and a processor. The user interface is configured to receive a nominal source impedance of the device under test. The processor is configured to receive the parameters for characterizing the probe from the memory and the nominal source impedance of the device under test from the user interface and to calculate an equalization filter using the parameters for characterizing the probe and nominal source impedance. The equalization filter is adapted to compensate for loading of the device under test caused by a measurement of the device under test. [0005] Certain other embodiments of the disclosed technology include a method for calculating an equalization filter for use in a test and measurement system. The method includes receiving at a processor parameters for characterizing a probe of a test and measurement system, receiving at the processor via a user interface a nominal source impedance of a device under test, and computing an equalization filter adapted to compensate for loading of a device under test caused by measurement of the device under test based on the parameters for characterizing the probe and the nominal source impedance of the device under test. BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG. 1 illustrates an ideal input waveform and the output waveform using a DUT with a 50 ohm source impedance loading the tip of the probe. [0007] FIG. 2 illustrates the ideal input waveform of the FIG. 1 and output waveforms with varying DUT source impedance values. [0008] FIG. 3 illustrates a block diagram of a test and measurement system of the disclosed technology. [0009] FIG. 4 illustrates a user interface of the disclosed technology. [0010] FIG. 5 illustrates another user interface of the disclosed technology. [0011] FIG. 6 illustrates a variety of equalization filters calculated using the disclosed technology. [0012] FIG. 7 illustrates an ideal input waveform and various output waveforms using different equalization filters for various DUT source impedance. DETAILED DESCRIPTION [0013] In the drawings, which are not necessarily to scale, like or corresponding elements of the disclosed systems and methods are denoted by the same reference numerals. [0014] Traditional accessories for test and measurement instruments are designed so that an accessory's optimal frequency response occurs when the tip of the accessory is connected to a circuit under test in a DUT with a source impedance of 50 ohms. Accessories tend to load the circuit under test in the DUT, which then distorts the waveform read from the circuit in the DUT. Conventionally, an accessory will incorporate hardware equalization to correct an output wave-shape to look more like it did before the accessory loaded the circuit. An equalization filter is calculated and used to process the acquired samples from the DUT such that signal degradation or artifacts imparted to the waveform read from the circuit under test and in the DUT are compensated for within the system, effectively de-embedding the loading of the DUT by the probe tip. FIG. 1 shows an output 100 response of a test and measurement instrument using the conventional approach given an ideal input pulse 102 . As can be seen in FIG. 1 , the output 100 shows some distortion. [0015] A DUT source impedance, however, tends to fall in the range of 25 ohms to 100 ohms. The DUT source impedance tends to vary over that range even if the DUT is specified to have a source impedance of 50 ohms. FIG. 2 shows in the conventional method how the outputs vary from the ideal input 102 shown in FIG. 1 when the source impedance of the DUT is not 50 ohms. As can be seen in FIG. 2 , the errors in the output waveforms can be quite large. [0016] The errors seen in FIG. 2 can be reduced by allowing a user to specify the nominal source impedance of the DUT to calculate an equalization filter. [0017] As seen in FIG. 3 , the system includes a test and measurement instrument 300 and a probe 302 connected to a DUT 304 . The test and measurement instrument 300 , may be for example, an oscilloscope. The test and measurement instrument may also be any other test and measurement instrument, such as a spectrum analyzer, logic analyzer, etc. [0018] The probe 302 includes a memory 306 for storing the S-parameters of the probe. Alternatively, the T-parameters or some other form of parameters to characterize the probe may be stored in the memory 306 . The parameters are measured at the time of manufacturing the probe 302 and then stored in memory 306 . Alternatively, the parameters may be stored in a memory 308 of the test and measurement instrument 300 , or on an external storage device (not shown), the internet (not shown), etc. The parameters merely must be supplied to the processor 310 to calculate the equalization filter as will be discussed in more detail below. [0019] The test and measurement instrument 300 also includes a memory 308 , as discussed above. Memory 308 stores the S-parameters of the test and measurement instrument 300 that are measured at the time of manufacturing. Alternatively, T-parameters or other forms of parameters to characterize the scope may be used and stored in memory 308 . Along with memory 308 , the test and measurement instrument 300 includes a display 312 and a processor 310 . [0020] During operation, the test and measurement instrument 300 is connected to the DUT 304 through the probe 302 . The display 312 contains a user menu or user interface 400 as shown in FIG. 4 . The user menu 400 allows the user to specify the nominal source impedance of the DUT 402 . The user can specify either the real impedance or the complex impedance of the DUT at the menu 402 . The nominal source impedance is then used as part of the calculation for the equalization filter to obtain an ideal target response for the system. [0021] The user menu 400 also contains an option for the user to turn the probe equalization filter on or off 404 . A user may turn off the equalization filter if the results for a particular DUT are better without the filter. The user menu 400 also allows a user to select whether to use nominal equalization view 406 . The nominal equalization view shows the waveform as if the probe did not load the DUT circuit. The user can also select the option of using a probe load filter 408 in the user menu. The probe load filter shows the voltage at the probe tip with the probe loading the DUT circuit. [0022] The user menu 400 may also include a menu 500 to allow a user to load the S-parameters for the DUT test point, as shown in FIG. 5 . The equalization filter is then computed using both the nominal impedance of the DUT and the S-parameters for the DUT test point. [0023] When the user has entered all the desired information into the user menu 400 on display 312 , the information is sent to processor 312 in the test and measurement instrument 300 . Further, the S-parameters of the probe stored in the probe memory 306 are also sent to the processor 310 in the test and measurement instrument 300 . The processor then uses the S-parameters of the probe, the nominal impedance of the DUT provided by the user to compute an equalization filter to provide a more accurate view of the signal from the DUT. To provide an even more accurate view, the processor may also use the S-parameters of the test and measurement instrument 300 stored in the test and measurement memory 310 and the S-parameters of the DUT if the S-parameters of the DUT are loaded into the test and measurement instrument 300 by the user via menu 500 . [0024] FIG. 6 illustrates the various equalization filters created by the processor 310 for each of the various nominal source impedance values. As can be seen in FIG. 6 , the equalization filters are different for each of the nominal source impedance values, which helps create a more accurate view on the display to the user of the signal from the circuit under test in the DUT. [0025] FIG. 7 illustrates output waveforms with the equalization filter applied using nominal input impedance values inputted by the user. For example, FIG. 6 shows an input waveform 700 and the output waveforms 702 for multiple DUT source impedance values. As can be seen in FIG. 7 , for each of the DUT source impedance values, after applying an equalization filter calculated with the nominal DUT impedance input by the user, the output waveforms are nearly identical to the input waveform, unlike the output waveforms shown in FIG. 2 . [0026] The disclosed technology allows a user to control the equalization filter applied to the tip of a probe. The user can specify a DUT source reference impedance at the probe tip and then an equalization filter is computed by the test and measurement instrument based on the measured S-parameters read from the probe. To create an even more refined equalization filter, the S-parameters of the test and measurement instrument and/or the test point of the DUT may be used. Although S-parameters are described above for calculating the equalization filter, as will be readily understood by one skilled in the art, other parameters may be used that characterize the probe, oscilloscope and/or the DUT test point, such as T-parameters. [0027] Although the embodiments illustrated and described above show the disclosed technology being used in an oscilloscope, it will be appreciated that embodiments of the present invention may also be used advantageously in any kind of test and measurement instrument that displays frequency domain signals, such as a swept spectrum analyzer, a signal analyzer, a vector signal analyzer, a real-time spectrum analyzer, and the like. [0028] In various embodiments, components of the invention may be implemented in hardware, software, or a combination of the two, and may comprise a general purpose microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or the like. [0029] Having described and illustrated the principles of the disclosed technology in a preferred embodiment thereof, it should be apparent that the disclosed technology can be modified in arrangement and detail without departing from such principles. We claim all modifications and variations coming within the spirit and scope of the following claims.

A test and measurement system including a test and measurement instrument, a probe connected to the test and measurement instrument, a device under test connected to the probe, at least one memory configured to store parameters for characterizing the probe, a user interface and a processor. The user interface is configured to receive a nominal source impedance of the device under test. The processor is configured to receive the parameters for characterizing the probe from the memory and the nominal source impedance of the device under test from the user interface and to calculate an equalization filter using the parameters for characterizing the probe and nominal source impedance from the user interface.

RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. application Ser. No. 10/177,683, filed Jun. 21, 2002, now pending, which is hereby incorporated by reference herein in its entirety. FIELD OF THE INVENTION [0002] The present invention relates to hydroxamate derivatives of non-steroidal anti-inflammatory drugs (NSAIDs). Invention compounds have multiple uses, for example, as prodrugs of NSAIDs, dual inhibitors of cyclooxygenase (COX) and 5-lipoxygenase (5-LO), as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinase enzymes (MMP)), and the like. In another aspect, the present invention relates to formulations containing invention compounds and methods for use thereof. BACKGROUND OF THE INVENTION [0003] A. NSAIDs [0004] Despite the advent of modern pharmaceutical technology, many drugs still possess untoward toxicities which often limit the therapeutic potential thereof. For example, although n on- s teroid a nti- i nflammatory d rugs (NSAIDs) are a class of compounds which are widely used for the treatment of inflammation, pain and fever, NSAIDs (e.g., naproxen, aspirin, ibuprofen and ketoprofen) can cause gastrointestinal ulcers, a side-effect that remains the major limitation to the use of NSAIDs (see, for example, J. L. Wallace, in Gastroenterol. 112:1000-1016 (1997); A. H. Soll et al., in Ann Intern Med. 114:307-319 (1991); and J. Bjarnason et al., in Gastroenterol. 104:1832-1847 (1993)). [0005] There are two major ulcerogenic effects of NSAIDs: (1) irritant effects on the epithelium of the gastrointestinal tract and (2) suppression of gastrointestinal prostaglandin synthesis. In recent years, numerous strategies have been attempted to design and develop new NSAIDs that reduce the damage to the gastrointestinal tract. These efforts, however, have largely been unsuccessful. For example, enteric coating or slow-release formulations designed to reduce the topical irritant properties of NSAIDs have been shown to be ineffective in terms of reducing the incidence of clinically significant side effects, including perforation and bleeding (see, for example, D. Y. Graham et al., in Clin. Pharmacol. Ther. 38:65-70 (1985); and J. L. Carson, et al., in Arch. Intern. Med., 147:1054-1059 (1987)). [0006] It is well recognized that aspirin and other NSAIDs exert their pharmacological effects through the non-selective inhibition of cyclooxygenase (COX) enzymes, thereby blocking prostaglandin synthesis (see, for example, J. R. Van in Nature, 231:232-235 (1971)). There are two types of COX enzymes, namely COX-1 and COX-2. COX-1 is expressed constitutively in many tissues, including the stomach, kidney, and platelets, whereas COX-2 is expressed only at the site of inflammation (see, for example, S. Kargan et al. in Gastroenterol., 111:445-454 (1996)). The prostaglandins whose production is mediated by COX-1 are responsible for many of their physiological effects, including maintenance of gastric mucosal integrity. [0007] Many attempts have been made to develop NSAIDs that only inhibit COX-2, without impacting the activity of COX-1 (see, for example, J. A. Mitchell et al., in Proc. Natl. Acad. Sci. USA 90:11693-11697 (1993); and E. A. Meade et al., in J. Biol. Chem., 268:6610-6614 (1993)). There are several NSAIDs presently on the market (e.g., rofecoxib and celecoxib) that show marked selectivity for COX-2 (see, for example, E. A. Meade, supra.; K. Glaser et al., in Eur. J. Pharmacol. 281:107-1 11 (1995) and Kaplan-Machlis, B., and Klostermeyer, B S in Ann Pharmacother. 33:979-88, (1999)). These drugs appear to have reduced gastrointestinal toxicity relative to other NSAIDs on the market. [0008] On the basis of encouraging clinical as well as experimental data, the development of highly selective COX-2 inhibitors appears to be a sound strategy to develop a new generation of anti-inflammatory drugs. However, the physiological functions of COX-1 and COX-2 are not always well defined. Thus, there is a possibility that prostagladins produced as a result of COX-1 expression may also contribute to inflammation, pain and fever. On the other hand, prostagladins produced as a result of COX-2 expression have been shown to play important physiological functions, including the initiation and maintenance of labor and in the regulation of bone resorption (see, for example, D. M. Slater et al., in Am. J. Obstet. Gynecol., 172:77-82 (1995); and Y. Onoe et al., in J. Immunol. 156:758-764 (1996)), thus inhibition of this pathway may not always be beneficial. Considering these points, highly selective COX-2 inhibitors may produce additional side effects above and beyond those observed with standard NSAIDs, therefore such inhibitors may not be highly desirable. [0009] Indeed, recent studies with first generation COX-2 inhibitors reveal that arthritic patients treated with rofecoxib had a five-fold higher risk of heart attack, compared to patients treated with naproxen (Wall St. Jrnl, 5/1/10). Thus, like aspirin, naproxen appears to exert cardioprotective effects, while selective COX-2 inhibitors do not. The reason why selective COX-2 inhibitors appear to cause elevated risk of heart attack has been studied (see Y. Cheng et al., in Science 296(19): 539-541 (2002)). Because of this potentially serious side effect of selective COX-2 inhibitors, there is still a need in the art for new NSAIDs (or derivatives thereof) with reduced gastrointestinal (GI) side effects. [0010] B. Dual Inhibitors of Cyclooxygenase (COX) and 5-Lipoxygenase (5-LO) [0011] The enzyme 5-LO is an iron-containing dioxygenase (see M. Gibian et al., in Bio-Org. Chem. 1: 117 (1977)) that catalyzes the first step of the biochemical pathway to convert arachidonic acid to leukotrienes. Leukotrienes are important mediators in inflammatory diseases including asthma, arthritis, psoriasis and allergy (see P, Sirois in Adv. Lipid Res. 21:79 (1995)). Inhibition of 5-LO is an important avenue for therapeutic treatment of these diseases. [0012] Hydroxamates are well known to form strong complexes with transition metal ions including iron (see H. Kiehl in The Chemistry And Biochemistry Of Hydroxyamic Acids, Karger, Basel (1982)). Some hydroxamates have shown good inhibitory activity against 5-LO (See, for example, J. B. Summers et al., in J. Med. Chem. 33:992-998(1990); A. O. Stewart et al., in J. Med. Chem. 40: 1955-1968 (1997); and T. Kolasa et al., in J. Med. Chem. 40:819-824 (1997)). [0013] As described above, NSAIDs are relatively non-specific COX inhibitors that commonly cause adverse effects, especially, gastrointestinal ulceration. A compound which provides inhibitory activities against both COX and 5-LO may provide improved anti-inflammatory activity with reduced NSAID-related side effects. Indeed, several research groups have studied dual inhibitors containing an hydroxamic acid group in their molecules (see T. Hidaka et al.,in Jpn. L. Pharmacol, 36: 77-85 (1984); H. Ikuta et al., in J. Med. Chem. 30:1995-1998 (1987); S. Wong et al., in Agents Actions 37:90-98(1992); P. C. Unangst et al., in J. Med. Chem. 37: 322-328 (1994); R. Richard L. et al., in J. Med. Chem. 39:246-252 (1996); and M. Inagak et al., in J. Med. Chem. 43:2040-2048 (2000)). In those studies, the molecule as an intact entity is designed to provide inhibitory activity against both COX and 5-LO. In general, however, these approaches have not proven to be very effective. [0014] Accordingly, there remains a need in the art for compounds which are more effective for the treatment of various inflammatory diseases with reduced NSAID-related side effects. [0015] C. Anticancer Drugs [0016] From experimental models of carcinogenesis, it has become apparent that NSAIDs have cancer chemopreventive properties, although their application to human cancer and the extent of their benefits in the clinic is presently a matter of intensive investigation (see G. A. Piazza et al., in Cancer Research, 57: 2452-2459 (1997)). While the results have been explained by reference to different mechanisms, many experiments have shown that NSAIDs have the potential to induce apoptosis (see, for example, K. Lundholm et al., in Cancer Research 54:5602-5606(1994); B. M. Bayer et al., in Biochem. Pharma. 28:441-443(1979), and in The J. Pharma. And Experiment. Therapeutics 210:106 (1979); N. N. Mahmoud et al., in Carcinogenesis 19:876-91(1998); V. Hial et al., in The J . Pharma. And Experiment. Therapeutics 202:446-454 (1977); B. Bellosillo et al., in Blood 92: 1406-1414(1998); N. E. Hubbard et al., in Cancer letters 43:111-120(1988); L. Qiao et al., in Biochem. Pharma. 55:53-64(1998); and S. J. Shiff et al., in Experimental Cell Res. 222: 179-188(1996)). [0017] Matrix metalloproteinases (MMPs), also called matrixines, are a family of structurally related zinc-containing enzymes that mediate the breakdown of connective tissue and are therefore targets for therapeutic inhibitors in many inflammatory, malignant and degenerative diseases (see M. Whittaker et al., in Chem. Rev. 99: 2735-2776 (1999)). Consequently a considerable amount of effort has been invested in designing orally active MMP inhibitors with the expectation that such agents will be able to either halt or slow the progression of diseases such as osteoarthritis, tumor metastasis, and corneal ulceration ( see M. Cheng et al ., 43: 369-380 (2000)). Since hydroxamate can form strong complexes with transition state metal ions including zinc, the vast majority of MMP inhibitors incorporate an hydroxamate group as the zinc binding ligand (see M. Whittaker et al., in Chem. Rev. 99: 2735-2776 (1999); B. Barlaam et al., 42:4890-4908(1999)). [0018] Accordingly, incorporation of the hydroxamate functionality into pharmacologically active compounds may provide novel compounds with enhanced anti-cancer activity and/or a reduced side effect profile. SUMMARY OF THE INVENTION [0019] In accordance with the present invention, there are provided novel chemical entities which have multiple utilities, e.g., as prodrugs of NSAIDs; as dual inhibitors of cyclooxygenase (COX) and 5-lipoxygenase (5-LO); as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinases (MMPs); as anti-diabetic agents; and the like. Invention compounds comprise a non-steroidal anti-inflammatory agent (NSAID), covalently linked via a suitable linker, to a hydroxamate. Invention compounds are useful alone or in combination with one or more additional pharmacologically active agents, and can be used for a variety of applications, such as, for example, treating inflammation and inflammation-related conditions; enhancing anti-inflammatory activity of NSAIDs; reducing the side effects associated with administration of anti-inflammatory agents; as anticancer agents (through promoting apoptosis and/or inhibiting matrix metalloproteinases (MMPs)); as anti-diabetic agents; and the like. [0020] Invention compounds are conjugate compounds of NSAIDs and hydroxamates, covalently linked in such a way that they can be broken into two individual molecules in the circulation system to provide their own inhibitory activity against COX and 5-LO, respectively. [0021] The NSAID component of invention compounds is capable of inducing apoptosis and the hydroxamate component is capable of inhibiting MMP. The two components are simultaneously administered as they are covalently linked, which in due course produces the original two components upon exposure to enzyme(s) in the circulatory system. Upon cleavage, the individual components are capable of contributing their cancer preventive activity with reduced NSAID-related side effects. BRIEF DESCRIPTION OF THE FIGURES [0022] [0022]FIG. 1 illustrates the total length of intestinal ulcers measured for rats treated with vehicle, diclofenac or equimolar invention compound 54. [0023] [0023]FIG. 2 illustrates the total length of gastric lesion measured for rats treated with vehicle, diclofenac or equimolar invention compound 54. [0024] [0024]FIG. 3 illustrates the inhibition of paw volume increase in the uninjected feet of Lewis rats in which arthritis was induced by injection of adjuvant into the footpad. DETAILED DESCRIPTION OF THE INVENTION [0025] In accordance with the present invention, there are provided compounds having the structure: [0026] wherein: [0027] X is C(O), C(O)O, S(O), S(O) 2 , C(S), C(O)S, C(S)S, C(S)O, and the like; [0028] Y is O or S; [0029] R 1 and R 2 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, alkoxy, substituted alkoxy, aryloxy, substituted aryloxy, heterocyclic, or substituted heterocyclic; or R 1 and R 2 together with N and X can form a cyclic moiety; and [0030] D-C(O)— is derived from a non-steroidal anti-inflammatory drug (NSAID) bearing a free carboxyl group. [0031] In a presently preferred embodiment of the invention, X is C(O) or S(O) 2 and Y is O. [0032] In another presently preferred embodiment of the present invention, R 1 and R 2 are each independently alkyl, substituted alkyl, aryl, substituted aryl, alkoxy, or substituted alkoxy. Substituents on R 1 and/or R 2 , when optionally present, include optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted heterocyclic, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted aryloxy, optionally substituted alkoxy, thioalkyl, hydroxyl, mercapto, alkylthio, alkylthioalkyl, halogen, trihalomethyl, cyano, nitro, nitrone, —C(O)H, carboxyl, alkoxycarbonyl, carbamate, sulfonyl, alkylsulfonyl, alkylsulfonylalkyl, sulfinyl, alkylsulfinyl, alkylsulfinylalkyl, sulfonamide, sulfuryl, amino, alkylamino, arylamino, aminosulfonyl, alkylaminosulfonyl, dialkylaminosulfonyl, amido, acyl, oxyacyl, —SO 3 M wherein M is H + , Li + , Na + , K + , NH 4 +, , and the like, or —PO 3 M wherein M is H + , Li + , Na + , K + , NH 4 + , and the like; or —OC(S)NR 3 , —OC(O)NR 3 , —C(S)NR 3 , —NR 3 C(S)R 3 , —NR 3 C(S)NR 3 , —OC(S)NR 3 , —NR 3 C(S)OR 3 , —C(S)OR 3 , —OC(S)R 3 , —OC(S)OR 3 , and the like, wherein R 3 is independently any of the substituents contemplated for R 1 and R 2 as defined herein. [0033] NSAIDs contemplated for incorporation into invention compounds include aspirin (i.e., acetylsalicylic acid), diclofenac, naproxen, indomethacine, flubiprofen, sulindac, ibuprofen, benoxaprofen, benzofenac, bucloxic acid, butibufen, carprofen, cicloprofen, cinmetacin, clidenac, clopirac, etodolac, fenbufen, fenclofenac, fenclorac, fenoprofen, fentiazac, flunoxaprofen, furaprofen, furobufen, furafenac, ibufenac, indoprofen, isoxepac, ketoprofen, Ionazolac, metiazinic, mefenamic acid, meclofenmic acid, piromidic acid, salsalate, miroprofen, oxaprozin, oxepinac, pirprofen, pirozolac, protizinic acid, suprofen, tiaprofenic acid, tolmetin, zomepirac, and the like. Presently preferred NSAIDs contemplated for incorporation into invention compounds include acetylsalicylic acid, diclofenac, naproxen, indomethacine, flubiprofen, sulindac, ibuprofen, and the like. [0034] As employed herein, “hydrocarbyl” comprises any organic radical wherein the backbone thereof comprises carbon and hydrogen only. Thus, hydrocarbyl embraces alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, alkylaryl, arylalkyl, arylalkenyl, alkenylaryl, arylalkynyl, alkynylaryl, and the like. [0035] As employed herein, “substituted hydrocarbyl” comprises any of the above-referenced hydrocarbyl groups further bearing one or more substituents selected from hydroxy, alkoxy (of a lower alkyl group), mercapto (of a lower alkyl group), cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, aryloxy, substituted aryloxy, halogen, trifluoromethyl, cyano, nitro, nitrone, amino, amido, —C(O)H, acyl, oxyacyl, carboxyl, carbamate, dithiocarbamoyl, sulfonyl, sulfonamide, sulfuryl, and the like. [0036] As employed herein, “alkyl” refers to saturated straight or branched chain hydrocarbon radical having in the range of 1 up to about 20 carbon atoms. “Lower alkyl” refers to alkyl groups having in the range of 1 up to about 5 carbon atoms. “Substituted alkyl” refers to alkyl groups further bearing one or more substituents as set forth above. [0037] As employed herein, “alkoxy” refers to —O-alkyl groups having in the range of 2 up to 20 carbon atoms and “substituted alkoxy” refers to alkoxy groups further bearing one or more substituents as set forth above. [0038] As employed herein, “cycloalkyl” refers to a cyclic ring-containing groups containing in the range of about 3 up to about 8 carbon atoms, and “substituted cycloalkyl” refers to cycloalkyl groups further bearing one or more substituents as set forth above. [0039] As employed herein, “cycloalkylene” refers to divalent ring-containing groups containing in the range of about 3 up to about 8 carbon atoms, and “substituted cycloalkylene” refers to cycloalkylene groups further bearing one or more substituents as set forth above. [0040] As employed herein, “alkylene” refers to saturated, divalent straight or branched chain hydrocarbyl groups typically having in the range of about 2 up to about 12 carbon atoms, and “substituted alkylene” refers to alkylene groups further bearing one or more substituents as set forth above. [0041] As employed herein, “oxyalkylene” refers to saturated, divalent straight or branched chain oxygen-containing hydrocarbon radicals typically having in the range of about 2 up to about 12 carbon atoms, and “substituted oxyalkylene” refers to oxyalkylene groups further bearing one or many substituents as set forth above. [0042] As employed herein, “alkenyl” refers to straight or branched chain hydrocarbyl groups having at least one carbon-carbon double bond, and having in the range of about 2 up to 12 carbon atoms, and “substituted alkenyl” refers to alkenyl groups further bearing one or more substituents as set forth above. [0043] As employed herein, “cycloalkenyl” refers to cyclic ring-containing groups containing in the range of 3 up to 20 carbon atoms and having at least one carbon-carbon double bond, and “substituted cycloalkenyl” refers to cycloalkenyl groups further bearing one or more substitutents as set forth above. [0044] As employed herein, “alkenylene” refers to divalent straight or branched chain hydrocarbyl groups having at least one carbon-carbon double bond, and typically having in the range of about 1 up to 12 carbon atoms, and “substituted alkenylene” refers to alkenylene groups further bearing one or more substituents as set forth above. [0045] As employed herein, “alkenylene” refers to divalent straight or branched chain hydrocarbyl groups having at least one carbon-carbon double bond, and typically having in the range of about 2 up to 12 carbon atoms, and “substituted alkenylene” refers to alkenylene groups further bearing one or more substituents as set forth above. [0046] As employed herein, “alkynyl” refers to straight or branched chain hydrocarbyl groups having at least one carbon-carbon triple bond, and having in the range of about 2 up to 12 carbon atoms, and “substituted alkynyl” refers to alkynyl groups further bearing one or more substituents as set forth above. [0047] As employed herein, “aryl” refers to aromatic groups having in the range of 6 up to 14 carbon atoms and “substituted aryl” refers to aryl groups further bearing one or more substituents as set forth above. [0048] Aryloxy [0049] As employed herein, “aryloxy” refers to —O-aryl groups having in the range of 6 up to 14 carbon atoms and “substituted aryloxy” refers to aryloxy groups further bearing one or more substituents as set forth above. [0050] As employed herein, “heteroaryl” refers to aromatic groups having in the range of 4 up to about 13 carbon atoms, and at least one heteroatom selected from O, N, S, or the like; and “substituted heteroaryl” refers to heteroaryl groups further bearing one or more substituents as set forth above. [0051] As employed herein, “alkylaryl” refers to alkyl-substituted aryl groups and “substituted alkylaryl” refers to alkylaryl groups further bearing one or more substituents as set forth above. [0052] As employed herein, “arylalkyl” refers to aryl-substituted alkyl groups and “substituted arylalkyl” refers to arylalkyl groups further bearing one or more substituents as set forth above. [0053] As employed herein, “arylalkenyl” refers to aryl-substituted alkenyl groups and “substituted arylalkenyl” refers to arylalkenyl groups further bearing one or more substituents as set forth above. [0054] As employed herein, “alkenylaryl” refers to alkenyl-substituted aryl groups and “substituted alkenylaryl” refers to alkenylaryl groups further bearing one or more substituents as set forth above. [0055] As employed herein, “arylalkynyl” refers to aryl-substituted alkynyl groups and “substituted arylalkynyl” refers to arylalkynyl groups further bearing one or more substituents as set forth above. [0056] As employed herein, “alkynylaryl” refers to alkynyl-substituted aryl groups and “substituted alkynylaryl” refers to alkynylaryl groups further bearing one or more substituents as set forth above. [0057] As employed herein, “arylene” refers to divalent aromatic groups typically having in the range of 6 up to 14 carbon atoms and “substituted arylene” refers to arylene groups further bearing one or more substituents as set forth above. [0058] As employed herein, “aralkylene” refers to aryl-substituted divalent alkyl groups typically having in the range of about 7 up to 16 carbon atoms and “substituted aralkylene” refers to aralkylene groups further bearing one or more substituents as set forth above. [0059] As employed herein, “aralkylene” refers to aryl-substituted divalent alkyl groups typically having in the range of about 7 up to 16 carbon atoms and “substituted aralkylene” refers to aralkylene groups further bearing one or more substituents as set forth above. [0060] As employed herein, “aralkenylene” refers to aryl-substituted divalent alkenyl groups typically having in the range of about 8 up to 16 carbon atoms and “substituted aralkenylene” refers to aralkenylene groups further bearing one or more substituents as set forth above. [0061] As employed herein, “aralkynylene” refers to aryl-substituted divalent alkynyl groups typically having in the range of about 8 up to 16 carbon atoms and “substituted aralkynylene” refers to aralkynylene group further bearing one or more substituents as set forth above. [0062] As employed herein, “heterocyclic” refers to cyclic (i.e., ring-containing) groups containing one or more heteroatoms (e.g., N, O, S, or the like) as part of the ring structure, and having in the range of 3 up to 14 carbon atoms and “substituted heterocyclic” refers to heterocyclic groups further bearing one or more substituents as set forth above. [0063] As employed herein, “heterocycloalkylene” refers to divalent cyclic (i.e., ring-containing) groups containing one or more heteroatoms (e.g., N, O, S, or the like) as part of the ring structure, and having in the range of 3 up to 14 carbon atoms and “substituted heterocycloalkylene” refers to heterocycloalkylene groups further bearing one or more substituents as set forth above. [0064] As employed herein, “aroyl” refers to aryl-carbonyl species such as benzoyl and “substituted aroyl” refers to aroyl groups further bearing one or more substituents as set forth above. [0065] As employed herein, “acyl” refers to alkyl-carbonyl species. [0066] As employed herein, “halogen” refers to fluoride, chloride, bromide or iodide atoms. [0067] As employed herein, reference to “a carbamate group” embraces substituents of the structure —O—C(O)—NR 2 , wherein each R is independently H, alkyl, substituted alkyl, aryl or substituted aryl as set forth above. [0068] As employed herein, reference to “a dithiocarbamate group” embraces substituents of the structure —S—C(S)—NR 2 , wherein each R is independently H, alkyl, substituted alkyl, aryl or substituted aryl as set forth above. [0069] As employed herein, reference to “a sulfonamide group” embraces substituents of the structure —S(O) 2 —NH 2 . [0070] As employed herein, “sulfuryl” refers to substituents of the structure ═S(O) 2 . [0071] As employed herein, “amino” refers to the substituent —NH 2 . [0072] As employed herein, “monoalkylamino” refers to a substituent of the structure —NHR, wherein R is alkyl or substituted alkyl as set forth above. [0073] As employed herein, “dialkylamino” refers to a substituent of the structure —NR 2 , wherein each R is independently alkyl or substituted alkyl as set forth above. [0074] As employed herein, “alkoxycarbonyl” refers to —C(O)O-alkyl groups having in the range of 2 up to 20 carbon atoms and “substituted alkoxycarbonyl” refers to alkoxycarbonyl groups further bearing one or more substituents as set forth above. [0075] As employed herein, reference to “an amide group” embraces substituents of the structure —C(O)—NR 2 , wherein each R is independently H, alkyl, substituted alkyl, aryl or substituted aryl as set forth above. When each R is H, the substituent is also referred to as “carbamoyl” (i.e., a substituent having the structure —C(O)—NH 2 ). When only one of the R groups is H, the substituent is also referred to as “monoalkylcarbamoyl” (i.e., a substituent having the structure —C(O)—NHR, wherein R is alkyl or substituted alkyl as set forth above) or “arylcarbamoyl” (i.e., a substituent having the structure —C(O)—NH(aryl), wherein aryl is as defined above, including substituted aryl). When neither of the R groups are H, the substituent is also referred to as “di-alkylcarbamoyl” (i.e., a substituent having the structure —C(O)—NR 2 , wherein each R is independently alkyl or substituted alkyl as set forth above). [0076] As employed herein, “organosulfinyl” refers to substituents having the structure —S(O)-organo, wherein organo embraces alkyl-, alkoxy- and alkylamino-moieties, as well as substituted alkyl-, alkoxy- or alkylamino-moieties. [0077] As employed herein, “organosulfonyl” refers to substituents having the structure —S(O) 2 -organo, wherein organo embraces alkyl-, alkoxy- and alkylamino-moieties, as well as substituted alkyl-, alkoxy- or alkylamino-moieties. [0078] In accordance with another embodiment of the present invention, there are provided synthetic methods for the preparation of invention compounds. For example, invention compounds can be prepared as illustrated in SCHEME 1. [0079] Thus, an NSAID bearing a free carboxyl group (or a carboxy-substituted NSAID) can be contacted with an appropriately substituted hydroxamic acid in the presence or absence of a catalyst (e.g., dimethylaminopyridine (DMAP)), and a suitable coupling agent (e.g., 1,3-dicyclohexylcarbodiimide (DCC)) under conditions suitable to form invention compounds shown in SCHEME 1. [0080] Similarly, thiohydroxamate derivatives of NSAIDs can be prepared as illustrated in SCHEME 2. [0081] Thus an NSAID bearing a free carboxyl group (or a carboxy-substituted NSAID) can be contacted with an appropriately substituted thiohydroxamate in the presence or absence of a catalyst (e.g. DMAP) and a suitable coupling agent (e.g. DCC) under conditions suitable to for invention compounds as shown in SCHEME 2. [0082] Employing similar synthetic strategies, a variety of heterocycle-containing derivatives of NSAIDs can be prepared, as illustrated, for example, in SCHEMEs 3 and 4. [0083] In accordance with yet another embodiment of the present invention, there are provided formulations containing invention compounds as described herein, in a pharmaceutically acceptable carrier. Optionally, invention formulations further comprise one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. Exemplary pharmaceutically acceptable carriers include solids, solutions, emulsions, dispersions, micelles, liposomes, and the like. Optionally, the pharmaceutically acceptable carrier employed herein further comprises an enteric coating. [0084] Pharmaceutically acceptable carriers contemplated for use in the practice of the present invention are those which render invention compounds (and optionally one or more additional pharmacologically active agents which are also effective for the treatment of the target indication) amenable to oral delivery, transdernal delivery, intravenous delivery, intramuscular delivery, topical delivery, nasal delivery, and the like. [0085] Thus, formulations of the present invention can be used in the form of a solid, a solution, an emulsion, a dispersion, a micelle, a liposome, and the like, wherein the resulting formulation contains one or more of the compounds of the present invention, as an active ingredient, in admixture with an organic or inorganic carrier or excipient suitable for enterable or parenteral applications. The active ingredient(s) may be compounded, for example, with the usual non-toxic, pharmaceutically acceptable carriers for tablets, pellets, capsules, suppositories, solutions, emulsions, suspensions and any other suitable for use. The carriers which can be used include glucose, lactose, gum acacia, gelatin, manitol, starch paste, magnesium trisilicate, talc, corn starch, keratin, colloidal silica, potato starch, urea, medium chain length triglycerides, dextrans, and other carriers suitable for use in manufacturing preparations, in solid, semisolid, or liquid form. In addition auxiliary, stabilizing, thickening, and coloring agents and perfumes may be used. The active compound(s) is (are) included in the formulation in an amount sufficient to produce the desired effect upon the process or disease condition. [0086] Invention formulations containing the active ingredient(s) may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Formulations intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such formulations may contain one or more agents selected from the group consisting of a sweetening agent such as sucrose, lactose, or saccharin, flavoring agents such as peppermint, oil of wintergreen or cherry, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets containing the active ingredient(s) in admixture with non-toxic pharmaceutically acceptable excipients used may be, for example (1) inert diluents such as calcium carbonate, lactose, calcium phosphate or sodium phosphate; (2) granulating and disintegrating agents such corn starch, potato starch or alginic acid; (3) binding agents such as gum tragacanth, corn starch, gelatin or acacia, and (4) lubricating agents such as maganesium stearate, steric acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed. They may also be coated by such techniques as those described in U.S. Pat. Nos. 4,256,108; 4,160,452; and 4,265,874, to form osmotic therapeutic tablets for controlled release. [0087] In some cases, formulations contemplated for oral use may be in the form of hard gelatin capsules wherein the active ingredient is mixed with inert solid diluent(s), for example, calcium carbonate, calcium phosphate or kaolin. They may also be in the form of soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example, peanut oil, liquid paraffin, or olive oil. [0088] Invention formulations may be in the form of a sterile injectable suspension. This suspension may be formulated according to known methods using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example, as a solution in 1,3-butanediol. Sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono- or diglycerides, fatty acids, naturally occurring vegetable oils like sesame oil, coconut oil, peanut oil, cottonseed oil, etc., or synthetic fatty vehicles like ethyl oleate or the like. Buffers, preservatives, antioxidants, and the like can be incorporated as required. [0089] Invention formulations may also be administered in the form of suppositories for rectal administration of the drug. These formulations may be prepared by mixing the drug with a suitable non-irritating excipient, such as cocoa butter, synthetic glyceride esters of polyethylene glycols, which are solid at ordinary temperatures, but liquefy and/or dissolve in the rectal cavity to release the drug. Since individual subjects may present a wide variation in severity of symptoms and each drug has its unique therapeutic characteristics, the precise mode of administration and dosage employed for each subject is left to the discretion of the practitioner. [0090] Amounts effective for the particular therapeutic goal sought will, of course, depend on the severity of the condition being treated, the optional presence of one or more additional pharmacologically active agents which are also effective for the treatment of the target indication, the weight and general state of the subject, and the like. Various general considerations taken into account in determining the “effective amount” are known to those of skill in the art and are described, e.g., in Gilman et al., eds., Goodman And Gilman's: The Pharmacological Bases of Therapeutics, 8th ed., Pergamon Press, 1990; and Remington's Pharmaceutical Sciences, 17th ed., Mack Publishing Co., Easton, Pa., 1990, each of which is herein incorporated by reference. [0091] The term “effective amount” as applied to invention compounds, means the quantity necessary to effect the desired therapeutic result, for example, a level effective to treat, cure, or alleviate the symptoms of a disease state for which the therapeutic compound is being administered, or to establish homeostasis. Since individual subjects may present a wide variation in severity of symptoms and each drug or active agent has its unique therapeutic characteristics, the precise mode of administration, dosage employed and treatment protocol for each subject is left to the discretion of the practitioner. [0092] In accordance with still another embodiment of the present invention, there are provided methods for treating inflammation and inflammation-related conditions. Such methods comprise administering to a subject in need thereof an effective amount of at least one invention compound as described herein, optionally in conjunction with one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. [0093] Subjects contemplated for treatment in accordance with the present invention include mammals such as rodents, canines, felines, farm animals, primates, and the like, including humans. [0094] Inflammation-related conditions contemplated for treatment in accordance with the present invention include arthritis (e.g rheumatoid arthritis, gouty arthritis, osteoarthritis, juvenile arthritis, systemic lupus erythematosus, spondyloarthopathies, and the like), gastrointestinal conditions (e.g., inflammatory bowel disease, Crohn's disease, gastritis, irritable bowel syndrome, ulcerative colitis, and the like), headache (e.g., migraine), asthma, bronchitis, menstrual cramps, tendinitis, bursitis, and the like. [0095] As readily recognized by those of skill in the art, inflammation-related conditions are associated with a variety of conditions, such as, for example, vascular diseases, periarteritis nodosa, thyroidiris, aplastic anemia, Hodgkin's disease, sclerodoma, rheumatic fever, diabetes (e.g., type I, type II, etc.), myasthenia gravis, colorectal cancer, sarcoidosis, nephrotic syndrome, Behcet's syndrome, potymyositis, gingivitis, hypersensitivity, conjunctivitis, swelling occurring after injury, myocardial ischemia, and the like. [0096] As readily recognized by those of skill in the art, a large number of pharmacologically active agents have been developed for treatment of the above-described indications. In accordance with the present invention, the effectiveness of many of these agents can be enhanced by administration in conjunction with invention compounds. For example, when invention compounds are employed for the treatment of diabetes, invention compounds can be administered in conjunction with one or more anti-diabetic compounds, such as, for example, insulin, metformin, acarbose, sulfonylureas, thiazolidine diones (e.g., rosiglitazone, piglitazone, and the like), and the like. [0097] Similarly, invention compounds can be administered in conjunction with one or more anti-arthritic compounds, anti-asthmatic compounds, anti-neoplastic compounds, and the like. [0098] When invention compounds are employed in conjunction with one or more additional pharmacologically active agents, the relative amounts of each active agent can vary widely, as can readily be determined by one of skill in the art. Typically the ratio of invention compound(s) to additional pharmacologically active agent(s) will fall in the range of about 1:10 up to about 10:1 [0099] In accordance with a further embodiment of the present invention, there are provided methods for reducing side effects associated with anti-inflammatory agents. Such methods comprise employing, for example, an effective amount of an invention compound as described herein. [0100] In accordance with yet another embodiment of the present invention, there are provided methods for promoting apoptosis in a subject. Such methods comprise administering to the subject an effective amount of an invention compound as described herein, optionally in conjunction with one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. [0101] In accordance with a further embodiment of the present invention, there are provided methods of inhibiting the proliferation of a hyperproliferative mammalian cell in a subject in need thereof. Such methods comprise administering to the subject an effective amount of an invention compound as described herein, optionally in conjunction with one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. [0102] In accordance with a still further embodiment of the present invention, there are provided methods for the treatment of cancer and/or tumor diseases through both promoting apoptosis and inhibiting MMP enzymes. Such methods comprise administering to the subject an effective amount of an invention compound as described herein, optionally in conjunction with one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. [0103] In accordance with a still further embodiment of the present invention, there are provided methods for enhancing anti-inflammatory activity by the dual inhibition of cyclooxygenase and 5-lipoxygenase in a subject in need thereof. Such methods comprise administering to the subject an effective amount of an invention compound as described herein, optionally in conjunction with one or more additional pharmacologically active agents which are also effective for the treatment of the target indication. [0104] The invention will now be described in greater detail with reference to the following non-limiting examples. EXAMPLES [0105] The syntheses described in Examples 1-14 are illustrated in SCHEME 5. Example 1 [0106] Compound 13 (Scheme 5). A solution of diclofenac (1) (2.96 g, 10 mmol), acetohydroxamic acid ( 2 ) (0.75 g, 10 mmol), 4-dimethylaminopyridine (DMAP) (0.12 g, 1 mmol) and 1,3-dicyclohexylcarbodiimide (DCC, 2.16 g, 10 mmol) was stirred at 0° C. for 3.5 h. The reaction mixture was filtered and the solvent was evaporated. The residue was partially dissolved in ethyl acetate and filtered. The ethyl acetate solution was washed with 0.5 N HCl solution, Na 2 CO 3 solution and water. The organic solution was dried (Na 2 SO 4 ) and the solvent was evaporated. The residue was purified by column chromatography on a silica gel column using CH 2 Cl 2 and then 200:1 CH 2 Cl 2 /hexanes as eluents to give 0.39 g (11%) of compound 13 as a solid compound; 1 H NMR(CDCl 3 ) δ2.04 (s, 3H), 3.99 (s, 2H, 1H ex D 2 O), 6.55-6.57 (m, 2H), 6.97-7.00 (m, 2H), 7.13-7.16 (t, 1H), 7.26 (s, 1H), 7.32-7.34 (d, 2H), 9.35 (br, 1H, ex D 2 O); MS (ESI) m/z 353 (M) + . Example 2 [0107] Compound 14 (Scheme 5). Compound 14 was synthesized from diclofenac (2.96 g, 10 mmol), compound 3 (1.05 g, 10 mmol), DMAP (0.12 g, 1 mmol) and DCC (2.06 g, 10 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 1.17 g (31%) of compound 14 as a white solid. 1 H NMR (CDCl 3 ) δ1.24 (t, 3H), 3.97 (d, 2H), 4.22 (q, 2H), 6.55-6.58 (m, 2H, 1H, ex D 2 O), 6.98 (t, 2H), 7.15 (t, 1H), 7.27 (d, 1H), 7.33 (d, 2H), 8.13 (s, 1H, ex D 2 O); MS (ESI) m/z 384 (M+H) + . Example 3 [0108] Compound 15 (Scheme 5). Compound 15 was synthesized from diclofenac (1) (1.48 g, 5 mmol), compound 4 (0.68 g, 5 mmol), DMAP (0.12 g, 1 mmol) and DCC (1.03 g, 5 mmol) employing the procedure described in Example 1. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 1.3 g (65%) of compound 15 as a white solid. 1 H NMR (CDCl 3 ) δ4.08 (s, 2H), 6.58-6.59 (m, 2H, 1H, ex D 2 O), 6.97-7.02 (m, 2H), 7.16 (t, 1H), 7.30-7.33 (m , 2H), 7.46 (t, 2H), 7.57 (t, 1H), 7.81 (d, 1H), 9.4 (br, 1H, ex D 2 O); MS (ESI) m/z 437.7 (M+Na) + . Example 4 [0109] Compound 16 (Scheme 5). Compound 16 was synthesized from diclofenac (1) (1.48 g, 5 mmol), compound 5 (0.84 g, 5 mmol), DMAP (0.12 g, 1 mmol) and DCC (1.03 g, 5 mmol) employing the procedure described in Example 1. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 0.93 g (42%) of compound 16 as a white solid. 1 H NMR (CDCl 3 ) δ3.97 (s, 2H), 5.19 (s, 2H), 6.53 (br, 1H, ex D 2 O), 6.57 (d, 1H), 6.96-7.00 (m, 2H), 7.16 (t, IH), 7.24 (d, 1H), 7.32-7.36 (m, 7H), 8.13 (s, 1H); MS (ESI) m/z 445.3 (M) + . Example 5 [0110] Compound 17 (Scheme 5). Compound 17 was synthesized from diclofenac (1) (1.48 g, 5 mmol), compound 6 (1.04 g, 5 mmol), DMAP (0.12 g, 1 mmol) and DCC (1.03 g, 5 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 1.9 g (77%) of compound 17 as a white solid. 1 H NMR (CDCl 3 ) δ3.95 (s, 2H), 6.38 (br, 1H, ex D 2 O), 6.54 (d, 1H), 6.94-6.99 (m, 2H), 7.13 (t, 1H), 7.18-7.32 (m, 11H), 7.52 (d, 2H); MS (ESI) m/z 491.5 (M) + . Example 6 [0111] Compound 18 (Scheme 5). Compound 18 was synthesized from diclofenac (1) (1.48 g, 5 mmol), compound 7 (0.58 g, 5 mmol), DMAP (0.12 g, 1 mmol) and DCC (1.03 g, 5 mmol) employing the procedure described in Example 1. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 1.04 g (48%) of compound 18 as a white crystal. 1 H NMR (CDCl 3 )δ1.36 (s, 6H), 3.63 (s, 2H), 4.01 (s, 2H), 6.51 (s, 1H, ex D 2 O), 6.57 (d, 1H), 6.98 (t, 2H), 7.16 (t, 1H), 7.26-7.28 (m, 2H), 7.33 (d, 2H), 9.19 (s, 1H, ex D 2 O); MS (ESI) m/z 429 (M) + . Example 7 [0112] Compound 8 (Scheme 5). To a solution of propionic acid (0.37 g, 0.37 ml, 5 mmol) and DMF (0.2 ml) in CH 2 Cl 2 , was added slowly oxalyl chloride (1.32 g, 0.92 ml, 10.25 mmol) at room temperature. The resulting solution was stirred at room temperature for 30 min. In a separate flask, to a solution of methylhydroxyamine hydrochloride (1.67 g, 20 mmol) in a mixed solvent of THF (10 ml) and H 2 O (1.5 ml) was added triethylamine (TEA) (4.2 ml, 30 mmol) at 0° C. and stirred for 20 min. The propionic acid-oxalyl chloride solution prepared above was slowly dripped into the methylhydroxylamine solution. Stirring of the resulting solution was continued at room temperature for 1 hour. A solution of 2N HCl (100 ml) was added to the reaction mixture. The solution was extracted three times with CH 2 Cl 2 . The CH 2 Cl 2 solution was dried with sodium sulfate (Na 2 SO 4 ) and the solvent was evaporated to give 80 mg (16%) of compound 7 as an oil. 1 H NMR (CDCl 3 ) δ1.19 (t, 3H), 1.62 (br, 1H, ex D 2 O), 2.35 (q, 2H), 3.33 (s, 3H); MS (ESI) m/z 103 (M) + . [0113] Compound 19 (Scheme 5). Compound 19 was synthesized from diclofenac (1) (0.23 g, 0.8 mmol), compound 8 (0.08 g, 0.8 mmol), DCC (0.16 g, 0.8 mmol) and DMAP (0.06 g, 0.5 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 150 mg (30%) of compound 19 as a solid. 1 H NMR (CDCl 3 ) δ1.03 (t, 3H), 2.19 (q, 2H), 3.29 (s, 3H), 3.94 (s, 2H), 6.54 (br, 1H, ex D 2 O), 6.58 (d, 1H), 6.99-7.02 (m, 2H), 7.17 (t, 1H), 7.27 (s, 1H), 7.35 (d, 2H); MS (ESI) m/z 381.4 (M) + . Example 8 [0114] Compound 9 (Scheme 5). A mixture of isopropylhydroxylamine hydrochloride and K 2 CO 3 in acetonitrile was stirred at room temperature for 2 h. A solution of isobutyl chloride in a 20 ml of CH 3 CN was dropped into the above mixture at 0° C. and then stirred at room temperature for 4 days. Water was added and the mixture was extracted four times with CH 2 Cl 2 . The organic phase was washed with brine and dried (Na 2 SO 4 ) and the solvent was evaporated to give 0.36 g (50%) of compound 9 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ1.17 (d, 6H), 1.32 (d, 6H), 2,72 (m, 1H), 4.25 (m, 1H), 8.3 (br, 1H, ex D 2 O); MS (ESI) m/z 144.4 (M−1) + . [0115] Compound 20 (Scheme 5). Compound 20 was synthesized from diclofenac (1) (0.23 g, 0.8 mmol), compound 9 (0.12 g, 0.8 mmol), DCC (0.16 g, 0.8 mmol) and DMAP (0.06 g, 0.5 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.3 g (88%) of compound 20 as a solid. 1 H NMR (CDCl 3 ) δ1.02 (d, 6H), 1.11 (d, 6H), 2.42 (m, 1H), 3.98 (s, 2H), 4.7 (m, 1H), 6.55 (br, 1H, ex D 2 O), 6.58 (d, 1H), 6.97-7.39 (m, 6H); MS (ESI) m/z 423.5 (M) + . Example 9 [0116] Compound 10 (Scheme 5). Compound 10 was synthesized from propionic acid (0.74 g, 0.74 ml, 10 mmol), isopropylhydroxyamine hydrochloride (2.22 g, 20 mmol) and oxalyl chloride (0.92 ml, 1.32 g, 10.25 mmol) employing the procedure described in the first paragraph of Example 7. The reaction generated 0.3 g (23%) of compound 10 as an oil. 1 H NMR (CDCl 3 ) δ1.20 (m, 3H), 1.31 (m, 6H), 2.37 (q, 2H), 4.17 (m, 1H), 8.21 (br, 1H, ex D 2 O); MS (ESI) m/z 132.2 (M+1) + . [0117] Compound 21 (Scheme 5). Compound 21 was synthesized from diclofenac (0.67 g, 2.2 mmol), compound 10 (0.3 g, 2.2 mmol), DCC (0.47 g, 2.3 mmol) and DMAP (0.04 g, 0.3 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.7 g (78%) of compound 21 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ1.03 (t, 3H), 1.09 (d, 6H), 2.15 (q, 1H), 3.98 (s, 2H), 4.76 (br, 1H), 6.57 (br, 1H, ex D 2 O), 6.57 (d, 1H), 6.98-7.36 (m, 6H); MS (ESI) m/z 431.9 (M+H) + . Example 10 [0118] Compound 11 (Scheme 5). Compound 11 was synthesized from (methylthio)acetic acid (1.06 g, 10 mmol), methylhydroxylamine hydrochloride (3.34 g, 40 mmol), and oxalyl chloride (1.84 ml, 20.5 mmol) employing the procedure described in the first paragraph of Example 7. The reaction generated 0.85 g (63%) of compound 11 as an oil. The compound was used to synthesize compound 22 without further purification. [0119] Compound 22 (Scheme 5). Compound 22 was synthesized from diclofenac (1.84 g, 6.2 mmol), compound 11 (0.85 g, 6.2 mmol), DCC (1.36 g, 6.6 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 and CH 2 Cl 2 /CH 3 OH (100/1) as eluents to give 0.91 g (36%) of compound 22 as a solid compound. 1 H NMR (CDCl 3 ) δ2.11 (s, 3H), 3.12(s, 2H), 3.35 (s, 3H), 3.96 (s, 2H), 6.47 (br, 1H, ex D 2 O), 6.58 (d, 1H), 6.98-7.35 (m, 6H); MS (ESI) m/z 413.5 (M) + . Example 11 [0120] Compound 23 (Scheme 5). To a solution of compound 22 (0.98 g, 2.4 mmol) in 30 ml of acetone was added 3-chloroperoxybenzoic acid (m-CPBA) (1.03 g, 6 mmol) at 0° C. The resulting solution was stirred at 0° C. for 2 h. A solution of sodium bisulfite was added and stirred at 0° C. for 5 min. Water was added to the above solution and stirred for 2 hrs. The suspension was filtered and the solid was dissolved in CH 2 Cl 2 and purified by column chromatography on a silica gel column using CH 2 Cl 2 and CH 2 Cl 2 /MeOH (50/1) as eluents to give 0.59 g (55%) of compound 23 as a solid. 1 H NMR (CDCl 3 ) δ3.08 (s, 3H), 3.38 (s, 3H), 3.92 (s, 2H), 3.99 (s, 2H), 6.34 (br, 1H, ex D 2 O), 6.57 (d, 1H), 6.99-7.04 (q, 2H), 7.18 (t, 1H), 7.28 (d, 1H), 7.35 (d, 2H); MS (ESI) m/z 447.9 (M+H) + . Example 12 [0121] Compound 24 (Scheme 5). To a solution of compound 22 (0.49 g, 1.2 mmol) in 30 ml of acetone was added 3-chloroperoxybenzoic acid (m-CPBA) (0.25 g, 1.42 mmol) at 0° C. The resulting solution was stirred at 0° C. for 2 h. A solution of sodium bisulfite was added and stirred at 0° C. for 5 min. Water was added to the above solution and stirred for 10 min. The mixture was extracted three times with CH 2 Cl 2 . The combined organic solution was washed with brine and dried (Na 2 SO 4 ). The solvent was evaporated and the residue was purified by column chromatography on a silica gel column using CH 2 Cl 2 and CH 2 Cl 2 /MeOH (50/1) as eluents to give 0.42 g (84%) of compound 24 as an oil. 1 H NMR (CDCl 3 ) δ264 (s, 3H), 3.34 (s, 3H), 3.55 (m, 1H), 3.58 (m, 1H), 3.98 (s, 2H), 6.44 (br, 1H, ex D 2 O), 6.57 (d, 1H), 7.01 (m, 2H), 7.18 (t, 1H), 7.28 (d, 1H), 7.33 (d, 2H); MS (ESI) m/z 451.5 (M+Na) + . Example 13 [0122] Compound 12 (Scheme 5). Compound 12 was synthesized from benzylthioglycolic acid (1.82 g, 10 mmol), methylhydroxylamine hydrochloride (3.34 g, 40 mmol), oxalyl chloride (1.84 ml, 2.64 g, 20.5 mmol), TEA (8.4 ml, 6.06 g, 60 mmol) and DMF (0.4 ml, 10 mmol) employing the procedure described in the first paragraph of Example 7. The reaction generated 2.1 g (99%) of compound 12 as a pale yellow oil; The compound was used to make compound 25 without further characterization. [0123] Compound 25 (Scheme 5). Compound 25 was synthesized from diclofenac (1) (2.96 g, 10 mmol), compound 12 (2.1 g, 10 mmol), DCC (2.06 g, 10 mmol) and DMAP (0.02 g, 0.2 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 3.6 g (74%) of compound 25 as an oil; 1 H NMR (CDCl 3 ) δ3.05 (s, 2H), 3.34 (s, 3H), 3.74 (s, 2H), 3.91 (s, 2H), 6.48 (br, 1H, ex D 2 O), 6.57-7.50 (m, 12H); MS (ESI) m/z 489.5 (M) + . Example 14 [0124] Compound 26 (Scheme 5). Compound 26 was synthesized from compound 25 (0.97 g, 2 mmol) and m-CPBA (0.51 g, 2.1 mmol) employing the procedure set forth in Example 11. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 0.62 g (60%) of compound 26 as a white crystal; 1 H NMR (CDCl 3 ) δ3.39 (s, 3H), 3.71 (s, 2H), 3.95 (s, 2H), 4.48 (s, 2H), 6.31 (br, 1H, ex D 2 O), 6.56-7.59 (m, 12H); MS (ESI) m/z 522.4 (M+H) + . [0125] The syntheses described in Examples 15-28 are illustrated in SCHEME 6. Example 15 [0126] Compound 27 (Scheme 6). A solution of hydroxylamine hydrochloride (1.38 g, 20 mmol) and TEA (4.2 ml, 3.03 g, 30 mmol) in a mixed solvent of 40 ml of THF and 6 ml of H 2 O was stirred at 0° C. for 15 min. A solution of p-toluenesulfonyl chloride (0.95 g, 5 mmol) in 10 ml of THF was dripped into the above solution at 0° C. The resulting solution was stirred at 0° C. for 2.5 h. Water (400 ml) was added and the solution was extracted with ethyl acetate twice. The combined organic solution was washed with H 2 O three times and dried (Na 2 SO 4 ). The solvent was evaporated and the residue was dissolved in CH 2 Cl 2 and cooled down to −10° C. to give white crystalline solid. The compound was dried to give 0.28 g (30%) of compound 27 as a white solid. 1 H NMR (CDCl 3 ) δ2.46 (s, 3H), 6.07 (d, 1H, ex D 2 O), 6.65 (d, 1H, ex D 2 O), 7.36 (d, 2H), 7.84 (d, 2H); MS (ESI) m/z 186.3 (M−H) − . [0127] Compound 39 (Scheme 6). Compound 39 was synthesized from diclofenac (1) (0.44 g, 1.5 mmol), compound 27 (0.28 g, 1.5 mmol), DCC (0.31 g, 1.5 mmol) and DMAP (0.012 g, 0.1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.23 g (33%) of compound 39 as an pale yellow solid. 1 H NMR (CDCl 3 ) δ2.21(s, 3H), 3.77 (s, 2H), 6.17 (s, 1H, ex D 2 O), 6.49 (d, 1H), 6.06-7.01 (q, 2H), 7.10-7.18(m, 4H), 7.32 (d, 2H), 7.68 (d, 2H), 8.98 (s, 1H, ex D 2 O); MS (ESI) m/z 451.5 (M+Na) + . Example 16 [0128] Compound 28 (Scheme 6). Compound 28 was synthesized from p-toluenesulfonyl chloride (0.95 g, 5 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 to give 0.69 g (68%) of compound 28 as a white solid. 1 HNMR (CDCl 3 ) δ2.47 (s, 3H), 2.82 (s, 3H), 6.35 (s, 1H, ex D 2 O), 7.37 (d, 2H), 7.78 (d, 2H). [0129] Compound 40 (Scheme 6). Compound 40 was synthesized from diclofenac (1) (0.3 g, 1 mmol) and compound 28 (0.2 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.42 g (87%) of compound 40 as a white foam; 1 H NMR (CDCl 3 ) δ2.37 (s, 3H), 3.02 (s, 3H), 3.83 (s, 2H), 6.31 (br, 1H, ex D 2 O), 6.56 (d, 1H), 6.96-7.00 (m, 2H), 7.15-7.19 (m, 2H), 7.24 (s, 2H), 7.32 (d, 2H), 7.65 (d, 2H); MS (ESI) m/z 502.2 (M+Na) + . Example 17 [0130] Compound 29 (Scheme 6). Compound 29 was synthesized from p-toluenesulfonyl chloride (0.95 g, 5 mmol) and isopropylhydroxylamine hydrochloride (1.2 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.33 g (29%) of compound 29 as a white solid. [0131] Compound 41 (Scheme 6). Compound 41 was synthesized from diclofenac (1) (0.42 g, 1.43 mmol), compound 29 (0.33 g, 1.43 mmol), DCC (0.3 g, 1.43 mmol) and DMAP (0.02 g, 0.2 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.39 g (54%) of compound 41 as pale yellow solid. 1 H NMR (CDCl 3 ) δ1.16 (d, 6H), 2.25 (s, 3H), 3.78 (s, 2H), 4.3 (m, 1H), 6.31 (br, 1H, ex D 2 O), 6.52 (d, 1H), 6.96-7.00 (m, 2H), 7.11-7.20 (m, 4H), 7.32 (d, 2H), 7.68 (d, 2H); MS (ESI) m/z 530.0 (M+Na) + . Example 18 [0132] Compound 30 (Scheme 6). Compound 30 was synthesized from 4-methoxybenzenesulfonyl chloride (1.03 g, 5 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) ) employing the procedure described in the first paragraph of Example 15. The compound was purified by simple extraction to give 0.63 g (58%) of compound 30 as a white solid. 1 H NMR (CDCl 3 ) δ2.81 (s, 3H), 3.89 (s, 3H), 3.75 (s, 1H, ex D 2 O), 7.04 (q, 2H), 7.82 (q, 2H). [0133] Compound 42 (Scheme 6). Compound 42 was synthesized from diclofenac (0.89 g, 3 mmol) and compound 30 (0.65 g, 3 mmol) employing the procedure described in Example 1. The compound was purified by chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.9 g (61 %) of compound 42 as a white solid. 1 H NMR (CDCl 3 ) δ3.02 (s, 3H), 3.81 (s, 3H), 3.84 (s, 2H), 6.31 (br, 1H ex D 2 O), 6.56 (d, 1H), 6.89 (d, 2H), 6.98 (q, 2H), 7.16 (q, 2H), 7.32 (d, 2H), 7.69 (d, 2H); MS (ESI) m/z 530.0 (M+Na) + . Example 19 [0134] Compound 31 (Scheme 6). Compound 31 was synthesized from methanesulfonyl chloride (0.81 ml, 1.2 g, 10 mmol) and methylhydroxylamine hydrochloride (1.66 g, 20 mmol) employing the procedure described in the first paragraph of Example 15. The reaction generated 0.63 g (50%) of compound 31 as a white solid. 1 H NMR ( CDCl 3 ) δ2.94 (s, 3H), 3.05 (s, 3H), 6.91 (s, 1H, ex D 2 O); MS (ESI) m/z 148.2 (M+Na) + . [0135] Compound 43 (Scheme 6). Compound 43 was synthesized from diclofenac (1.48 g, 5 mmol) and compound 31 (0.63 g, 5 mmol) employing the procedure described in Example 1. The compound was purified by crystallization using CH 2 Cl 2 /hexanes to give 1.47 g (73%) of compound 43 as a white solid. 1 H NMR (CDCl 3 ) δ2.91 (s, 3H), 3.17 (s, 3H), 3.94 (s, 2H), 6.47 (br, 1H, ex D 2 O), 6.59 (d, 1H), 6.98 (q, 2H), 7.16 (t, 1H), 7.26 (s, 1H), 7.34 (d, 2H); MS (ESI) m/z 403.5 (M) + . Example 20 [0136] Compound 32 (Scheme 6). Compound 32 was synthesized from 4-nitrobenzenesulfonyl chloride (1.11 g, 5 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. Purification by extraction gave 0.6 g (52%) of compound 32 as an yellow solid. [0137] Compound 44 (Scheme 6). Compound 44 was synthesized from diclofenac (0.76 g, 2.6 mmol), compound 32 (0.6 g, 2.6 mmol), DCC (0.62 g, 3 mmol) and DMAP (0.02 g, 0.2 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.97 g (73%) of compound 44 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ3.11 (s, 3H), 3.83 (s, 2H), 6.15 (br, 1H, ex D 2 O), 6.54 (d, 1H), 6.98-7.04 (m, 2H), 7.16-7.26 (m, 2H), 7.32 (d, 2H), 7.84 (q, 2H), 8.19 (q 2H); MS (ESI) m/z 511 (M+H) + . Example 21 [0138] Compound 33 (Scheme 6). Compound 33 was synthesized from ethanesulfonyl chloride (1.28 g, 10 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by simple extraction to give 0.97 g (70%) of compound 33 as a white oil. 1 H NMR (CDCl 3 ) δ1.46 (t, 3H), 3.08 (s, 3H), 3.18 (q, 2H), 6.49 (s, 1H, ex D 2 O). [0139] Compound 45 (Scheme 6). Compound 45 was synthesized from diclofenac (1.95 g, 6.6 mmol), compound 33 (0.92 g, 6.6 mmol), DCC (1.36 g, 6.6 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 2.1 g (76%) of compound 45 as a white solid. 1 H NMR (CDCl 3 ) δ1.36 (t, 3H), 3.02 (q, 2H), 3.17 (s, 3H), 3.92 (s, 2H), 6.5 (br, 1H ex D 2 O), 6.58 (d, 1H), 7.00 (t, 2H), 7.16 (t, 1H), 7.26 (q, 1H), 7.34 (d, 2H); MS (ESI) m/z 417.4 (M) + . Example 22 [0140] Compound 34 (Scheme 6). Compound 34 was synthesized from 3-(trifluoromethyl)benzenesulfonyl chloride (1.22 g, 5 mmol), methylhydroxyamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified simply by extraction to give 0.65 g (51%) of compound 34 as a solid. [0141] Compound 46 (Scheme 6). Compound 46 was synthesized from diclofenac (0.74 g, 2.5 mmol), compound 34 (0.65 g, 2.5 mmol), DCC (0.51 g, 2.5 mmol) and DMAP (0.02 g, 0.2 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.46 g (35%) of compound 46 as a white solid; 1 H NMR (CDCl 3 ) δ3.05 (s, 3H), 3.85 (s, 2H), 6.27 (br, 1H, ex D 2 O), 6.57 (d, 1H), 6.97-7.01 (q, 2H), 7.17-7.18 (m, 2H), 7.32 (d, 2H), 7.60 (t, 1H), 7.88 (d, 2H), 8.14 (s, 1H); MS (ESI) m/z 533.7 (M) + . Example 23 [0142] Compound 35 (Scheme 6). Compound 35 was synthesized from butylsulfonyl chloride (1.56 g, 10 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by simple extraction to give 1.46 g (87%) of compound 35 as a white solid. 1 H NMR ( CDCl 3 ) δ0.97 (t, 3H), 1.50 (m, 2H), 1.88 (m, 2H), 3.06 (s, 2H), 3.13 (t, 2H), 6.80 (br, 1H, ex D 2 O). [0143] Compound 47 (Scheme 6). Compound 47 was synthesized from diclofenac (2.58 g, 8.7 mmol), compound 35 (1.46 g, 8.7 mmol), DCC (1.79 g, 8.7 mmol) and DMAP (0.1 2 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 /Hexanes as an eluent to give 2.1 g (54%) of compound 47 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ0.85 (t, 3H), 1.32 (m, 2H), 1.77 (m, 2H), 2.95 (t, 2H), 3.16 (s, 3H), 3.92 (s, 2H), 6.54 (br, 1H, ex D 2 O), 6.58 (d, 1H), 7.00 (m, 2H), 7.16 (t, 1H), 7.26 (d, 1H), 7.36 (d, 2H); MS (ESI) m/z 478.4 (M+Na) + . Example 24 [0144] Compound 36 (Scheme 6). Compound 36 was synthesized from 2-mesitylenesulfonyl chloride (2.18 g, 10 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by simple extraction to give 1.5 g (66%) of compound 36 as a white solid. 1 H NMR ( CDCl 3 ) δ2.31 (s, 3H), 2.66 (s, 6H), 3.02 (s, 3H), 6.98(s, 1H); MS (ESI) m/z 252.5 (M+Na) + . [0145] Compound 48 (Scheme 6). Compound 48 was synthesized from diclofenac (1) (1.93 g, 6.5 mmol), compound 36 (1.5 g, 6.5 mmol), DCC (1.33 g, 6.5 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 2.84 g (86%) of compound 48 as an pale yellow solid. 1 H NMR (CDCl 3 ) δ1.96 (s, 3H), 2.67 (s, 6H), 3.21 (s, 3H), 3.51 (s, 2H), 6.21 (br, 1H, ex D 2 O), 6.44 (d, 1H), 6.77 (s, 2H), 6.90 (t, 1H), 6.98 (t, 1H), 7.09 (t, 1H), 7.33 (d, 2H); MS (ESI) m/z 507.0 (M) + . Example 25 [0146] Compound 37 (Scheme 6). Compound 37 was synthesized from propanesulfonyl chloride (1.42 g, 10 mmol) and methylhydroxylamine hydrochloride (0.83 g, 10 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by simple extraction to give 1.35 g (88%) of compound 37 as a white oil. 1 H NMR ( CDCl 3 ) δ1.09 (t, 3H), 1.94 (m, 2H), 3.09 (s, 3H), 3.11 (t, 2H); MS (ESI) m/z 176.2 (M+Na) + . [0147] Compound 49 (Scheme 6). Compound 49 was synthesized from diclofenac (1) (2.53 g, 8.55 mmol), compound 37 (1.31 g, 8.55 mmol), DCC (1.79 g, 8.7 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 2.0 g (88%) of compound 49 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ0.95 (t, 3H), 1.83 (m, 2H), 2.92 (t, 2H), 3.16 (s, 3H), 3.92 (s, 2H), 6.53 (br, 1H, ex D 2 O), 6.57 (d, 1IH), 7.01 (t, 2H), 7.16 (t, 11H), 7.26 (d, 11H), 7.35 (d, 2H); MS (ESI) m/z 431.8 (M+H) + . Example 26 [0148] Compound 38 (Scheme 6). Compound 38 was prepared from 2-mesitylenesulfonyl chloride (2.18 g, 10 mmol), hydroxyamine hydrochloride (1.38 g, 20 mmol) employing the procedure described in the first paragraph of Example 15. The compound was purified by column chromatography on a silica gel column to give 1.07 g (50%) of the compound 38 as a white solid. 1 H NMR (CDCl 3 ) δ2.26 (s, 3H), 3.32 (s, 6H), 9.24 (d, 1H, ex D 2 O), 9.41 (d, 1H, ex D 2 O). [0149] Compound 50 (Scheme 6). Compound 50 was prepared from diclofenac (1) (0.55 g, 1.85 mmol), compound 38 (0.4 g, 1.85 mmol), DCC (0.38 g, 1.85 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.5 g (55%) of compound 50 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ2.09 (s, 3H), 2.63 (s, 6H), 2.75 (s, 2H), 6.21 (br, 1H, ex D 2 O), 6.48 (d, 1H), 6.84 (s, 2H), 6.95 (t, 1H), 6.99 (t, 1H), 7.13 (t, 1H), 7.33 (d, 2H); MS (ESI) m/z 494.5 (M+H) + . Example 27 [0150] Compound 51 (Scheme 6). To a stirring solution of compound 39 in dimethylformamide at room temperature under N 2 is added sodium hydride. The resulting mixture was stirred at room temperature for 1 h. Propane sultone was added to the above solution and stirred at room temperature overnight to give the desired compound 51 after purification. Example 28 [0151] Compound 52 (Scheme 6). Compound 52 is prepared from compound 39 and 1,4-butane sultone employing the procedure described in Example 27. The compound is purified by column chromatography on a silica gel column. Example 29 [0152] The synthesis described in Example 29 is illustrated in SCHEME 7. [0153] Compound 54 (Scheme 7). Compound 54 was synthesized from diclofenac (1) (1.48 g, 5 mmol), compound 53 (0.73 g, 5 mmol), DCC (1.03 g, 5 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by crystallization from CH 2 Cl 2 /hexanes to give 0.77 g (36%) of compound 54 as a white solid. 1 H NMR (CDCl 3 ) δ2.06 (d, 3H), 4.24 (d, 2H), 6.21 (s, 1H), 6.98-7.03 (m, 2H), 7.19 (t, 1H), 7.33-7.36 (m, 3H); MS (ESI) m/z 451.2 (M+Na) + . Example 30 [0154] The syntheses described in Example 30 is illustrated in SCHEME 8. [0155] Compound 56 (Scheme 8). Compound 56 was synthesized from diclofenac (1) (0.89 g, 3 mmol), compound 55 (0.49 g, 3 mmol), DCC (0.62 g, 3 mmol) and DMAP (0.12 g, 1 mmol) employing the procedure described in Example 1. The compound was purified by column chromatography on a silica gel column using CH 2 Cl 2 as an eluent to give 0.4 g (30%) of compound 56 as a pale yellow solid. 1 H NMR (CDCl 3 ) δ4.29 (s, 2H), 6.36 (br, 1H, ex D 2 O), 6.64 (d, 1H), 6.98 (t, 1H), 7.78 (t, 1H), 7.21 (t, 1H), 7.32 (d, 2H), 7.42 (d, 1H), 7.85 (t, 1H), 8.01 (t, 1H), 8.24 (d, 1H), 8.38 (d, 1H); MS (ESI) m/z 431.8 (M+H) + . Examples 31-44 [0156] The syntheses of compounds 58-71 are described in Examples 31-44, respectively. The synthetic strategies employed are illustrated in SCHEME 9. [0157] Compounds 58-71 (Scheme 9). Compounds 58-71 are synthesized as described above for the preparation of compounds 13-26, respectively, employing naproxene (57), DCC, DMAP and compounds 2-12 as starting materials. The compounds are purified by either crystallization or column chromatography. Examples 45-58 [0158] The syntheses of compounds 72-85 are described in Examples 45-58, respectively. The synthetic strategies employed are illustrated in SCHEME 10. [0159] Compounds 72-85 (Scheme 10). Compounds 72-85 are synthesized as described above for the preparation of compounds 39-52, respectively, employing naproxene (57) and compounds 27-38 as starting materials. The compounds are purified by either column chromatography or crystallization. Examples 59-72 [0160] The syntheses of compounds 87-100 are described in Examples 59-72, respectively. The synthetic strategies employed are illustrated in SCHEME 11. [0161] Compounds 87-100 (Scheme 11). Compounds 87-100 are synthesized as described above for the preparation of compounds 13-26, respectively, employing indomethacine (86), DCC, DMAP and compounds 2-12 as starting materials. The compounds are purified by either crystallization or column chromatography. Examples 73-86 [0162] The syntheses of compounds 101-114 are described in Examples 73-86, respectively. The synthetic strategies employed are illustrated in SCHEME 12. [0163] Compounds 101-114 (Scheme 12). Compounds 101-114 are synthesized as described above for the preparation of compounds 39-52, respectively, employing indomethacine (86) and compounds 27-38 as starting materials. The compounds are purified by either column chromatography or crystallization. Example 87 [0164] An invention compound, Compound 54 (a pro-drug of Diclofenac), was evaluated for its safety profile in rat models of gastropathy and enteropathy. Compound 54 exhibited significantly less gastric lesion formation and ulcer formation than equivalent doses of Diclofenac. In adjuvant-induced arthritis model, compound 54 exhibited equivalent efficacy to equimolar doses of Diclofenac. [0165] Gastropathy: Male Sprague-Dawley rats (150-174 g) were obtained from Harlan (San Diego, Calif.). Animals were allowed to acclimatize to the facility for a minimum of 3 days and provided food and water ad libitum until the day before the study. Rats were fasted for 18 hours prior to the study. Diclofenac sodium salt was formulated in PBS, and dosed at 5 ml/kg, and Compound 54 was formulated in polyethyleneglycol (PEG) (MW. 300; Sigma Chemical Co., St. Louis, Mo.), and dosed at 1 ml/kg. Drugs were administered orally as a single dose in the morning and water removed. Two and one-half hours after dosing, rats were injected with 1 ml of 10 mg/ml Evans Blue solution and sacrificed 30 minutes later. Stomachs were removed, placed in weigh boats containing cold PBS, and re-coded with letters to blind the observer. Stomachs were then opened along the greater curvature, any contents removed and then placed flat with the lumen facing up to score blue-stained lesions for gastric toxicity according to the following criteria: First, the number of small rounded lesions were counted followed by measurement of total length of linear lesions of greater than or equal to 2 mm. The two numbers obtained (round lesion number and linear length) were added together to give a total gastropathy score expressed as Total Gastric Lesions. [0166] [0166]FIG. 1 illustrates the total length of intestinal ulcers measured for rats treated with vehicle, diclofenac or equimolar invention compound 54. Diclofenac caused substantial ulceration, while compound 54 had no ulcerogenic effect, just like the vehicle PEG. [0167] Enteropathy: Male Sprague-Dawley rats (150-174 g) were obtained from Harlan. Animals were allowed to acclimatize to the facility for a minimum of 3 days and provided with food and water ad libitium. Diclofenac sodium salt was formulated in PBS, and dosed at 5 ml/kg, and compound 54 was formulated in polyethyleneglycol (MW. 300; Sigma Chemical Co.), dosed at 1 ml/kg. Drugs were administered orally either as a single dose (late morning) or twice daily between 8:00-10:00 and 4:00-5:00 beginning with a morning dose for a total of three days. Groups contained 6-8 animals per treatment. On the fourth day each rat was injected intravenously with 1 ml of a 10 mg/ml solution of Evan's Blue to stain the damaged blood vessels in intestinal erosions and ulcers. Animals were sacrificed 10 to 20 minutes after administration of Evan's Blue. The small intestine was then removed from each rat and placed in a large weigh boat in cold PBS, stored briefly in a refrigerator until boats were re-coded to blind the observer. Each intestinal segment was then opened longitudinally and, using a fiber optic light, scored for erosions and ulceration according to the following criteria: [0168] Erosions: An erosion is a shallow lesion that does not penetrate past the muscularis mucosa immediately below the epithelium. After Evan's Blue injection, intestinal lesions are seen as shallow lesions that are moderately stained around the edge, but with little to no staining in the middle. The depth of an erosion is sometimes only detectable when the edge of the tissue is lifted to reflect light at a different angle. Erosions are usually small and round or oval, but are sometimes as much as 1-2 mm wide, and as long as 1-2 cm, running along the area of mesenteric attachment. When erosions are elongated, the length is measured in mm and divided by 2; otherwise, the erosions are merely counted individually. Note that some areas of intestinal tissue stain blue, but are not erosions. These tend to be near the mesenteric membrane attachment sites and may represent areas of increased permeability that have not progressed to the extent that cell loss has occurred. When such areas are viewed while lifting the edge of the tissue, there is no clear depression in the center, and often the mesentery below contributes significantly to the observed staining. [0169] Ulcers: An ulcer is a deep lesion penetrating the muscularis mucosa. It is usually thickened and inflamed. After Evan's Blue injection, ulcers present several different types of appearance. Small ulcers are round and oval, thickened and darkly stained (including the center), often with a small white scab on top. Larger ulcers are usually linear, running along the area where the mesenteric membrane attaches. The resulting trough can either be deep (e.g., ˜1 mm) and empty, or filled with granulation tissue. The surrounding intestine is almost always thickened and inflamed. All ulcers are quantified by measuring their long dimensions in mm. [0170] [0170]FIG. 2 illustrates the total length of gastric lesion measured for rats treated with vehicle, diclofenac or equimolar invention compound 54. Compound 54 caused 73% less lesion than did an equimolar dose of diclofenac. [0171] Adjuvant-induced Arthritis: Male Lewis rats (175-199 g) were obtained from Harlan (San Diego, Calif.). Animals were allowed to acclimatize to the facility for a minimum of 3 days and provided food and water ad libitium. Mycobacterium tuberculosis (Difco, Bacto H37 RA 3114-25) was dissolved in mineral oil (5 mg/ml) and arthritis induced by injecting 100 μl of the solution into the left footpad using a 25G needle. Paw volume was measured using a water plethysmometer (UBS Basile, Stoelting Co.). A line was drawn across the right ankle to provide the level for baseline measurement of paw volume and paw volume was measured on days 0, 5, 11, 13 and 15. Data is expressed as percent inhibition paw swelling on day 15 which is calculated as follows: % inhibition=(1−((Vol drug-treated day 15 −Vol drug-treated day 5 )/(Vol vehicle treated day 15 −Vol vehicle-treated day 5 )))×100. Diclofenac sodium salt was formulated in PBS, and dosed at 5 ml/kg, and Compound 54 was formulated in polyethyleneglycol (MW. 300; Sigma Chemical Co., St. Louis, Mo.), and dosed at 1 ml/kg. Diclofenac, compound 54 and vehicle were administered orally, daily, on days 8-15. [0172] [0172]FIG. 3 illustrates the inhibition of paw volume increase in the uninjected feet of Lewis rats in which arthritis was induced by injection of adjuvant into the footpad. Invention compound 54 displayed anti-inflammatory activity similar to diclofenac in the chronic adjuvant arthritis model. [0173] It will be apparent to those skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof, and therefore, the invention encompasses embodiments in addition to those specifically disclosed in the specification, but only as indicated in the appended claims.

In accordance with the present invention, there are provided novel chemical entities which have multiple utilities, e.g., as prodrugs of NSAIDs; as dual inhibitors of cyclooxygenase (COX) and 5-lipoxygenase (5-LO); as anticancer agents (through promoting apoptosis and/or inhibiting the matrix metalloproteinases (MMPs)); as anti-diabetics; and the like. Invention compounds comprise a non-steroidal anti-inflammatory agent (NSAID), covalently linked to a hydroxamate. Invention compounds are useful alone or in combination with one or more additional pharmacologically active agents, and can be used for a variety of applications, such as, for example, treating inflammation and inflammation-related conditions; reducing the side effects associated with administration of anti-inflammatory agents; promoting apoptosis; inhibiting matrix metalloproteinases; as anti-diabetic agents; and the like.

FIELD OF THE INVENTION [0001] The present invention is applied generally to the field of telecommunication networks and more particularly this invention relates to configuration, reconfiguration and monitoring of network nodes in networks providing Internet Protocol (IP) connectivity. [0002] More precisely, the present invention discloses a method for simplifying the task of logical deployment to configure a target IP network topology which is to be physically deployed on a background IP network, as well as the inverse task of logical undeployment is simplified. Furthermore, this method allows real time monitoring on the network elements previously deployed in, the target IP network. STATE OF THE ART [0003] Conventional management systems, such as Simple Network Management Protocol (SNMP) [D. Harrington, R. Presuhn, B. Wijnen, “An Architecture fot Describing Simple Network Management. Protocol (SNMP) Management Frameworks”, IETF Standard 62, RFC 3411, December 2002] or Web Based Enterprise. Management (WBEN) [Distributed Management Task Force, “Specification of CIM Operations over HTTP”, Version 1.1, DMTF Standard DSP0200, January 2003]) are based on two functional entities: agents and managers. Agents run in the devices that are being managed and are aware of the internal information and parameters needed for management. Managers connect to agents in order to perform management operations. [0004] The communication between agents and managers is based in an information model, that is, a structured way of describing the management data (for example, CPU load, IP addresses, etc.) and a communication protocol to exchange that information. For example, in the case of SNMP management framework, with SNMP as the communication protocol, the information model is composed of MIBs (Management Information Base) defined in a standardized text-based information structured language called ASN.1 (Abstract Syntax Notation 1). [0005] However, these management systems have some drawbacks for the deployment of global configurations involving several network elements in IP networks. On the one hand, they are very strict in terms of requirements of communication protocol and information model, which are described as part of the management system. Said communication protocol and information model are often incompatible with the communication interfaces of devices provided by certain vendors. On the other hand, well-known management systems provide very simple management operations (“get” and “set” in most of the cases), which make said systems unsuitable for complex configurations. Moreover, when using these well-known management systems, each network element is managed individually, and therefore the management system does not have a global view of the whole network to be configured. [0006] Solutions to these problems usually, rely on building top-level manager applications, which act as front-ends of the network management system. However, these applications are difficult to design and implement. [0007] In addition, a currently widely used industrial standard for data interchange is the eXtensible Markup Language (XML). XML is a World Wide Web Consortium-recommended general-purpose markup language for creating special-purpose markup languages. It is a simplified subset of the Standard Generalized Markup Language (SGML). The primary purpose of XML is to facilitate the sharing of data across different systems, particularly systems connected via the Internet. Many languages based on XML (for example, Geography Markup Language (GML), RDF/XML, RSS, Atom, MathML, XHTML, SVG, Klip and MusicXML) are defined in a formal way, allowing programs to modify and validate documents in these languages without prior knowledge of their particular form. [0008] Network management systems based on XML are described in US 2004/0117452 A1. In particular, US 2004/0117452 A1 describes a network management system and method which employs tree-shaped configurations for individually managed network elements. [0009] With the aim at simplifying the network management, it would be desirable to provide a straightforward data model that defines the global network configuration and eases its management globally, instead of having managed the individual network elements, without being tied to a particular Configuration of each network element. [0010] The model-focused approach has been already successfully applied to other engineering fields, such as software production in the Model Driven Architecture (MDA) framework, [Object Management Group, “MDA Guide Version 1.0.1”, OMG Document Number omg/2003-06-01, June 2003], based on technology-agnostic models of software applications and processing these models in order to build platform-dependent code implementing the desired applications. [0011] On the other hand, a well known management field is Service oriented Provisioning, which requires the network operator to engineer the way in that services are created and distributed into a network, so that a telecom service provider can define his service offering as a specific set of services. US 2002/0178252 discloses some example of mechanisms for Service Provisioning. However, implementing Service Provisioning is focused on the final user (in one end of the network) and does not consider network topology configuration at all. US 2002/0178252 describes a procedural processing of the service configuration based on workflows and does not consider declarative descriptions of configuration. [0012] In contrast to Service Provisioning, the whole network and not just the user end must be taken into account in network topology configuration (as a matter of fact, in some management contexts, such as experimentation infrastructures or testbeds, there is no a final user). Network topology configuration deals with how to define, and configure arbitrary interconnections among network elements, and so declarative descriptions of the network configuration are required. Declarative descriptions can be used from a high-level user perspective to describe the configuration wanted by the user, without specification of the means needed to get that configuration (this specification of the means used by the management engine is needed for the service provisioning mechanism disclosed in US 2002/0178252 in the form of workflow definitions). SUMMARY OF THE INVENTION [0013] One aspect of the present invention is a method for logical deployment of global target network configurations based on a data model defining the intended global network configuration. In this context, “logical” means that the goal is the deployment of a target network on top of an exiting background network, already physically deployed, taking advantage of IP technology to build overlay networks. Besides, this invention provides complementary methods for logical undeployment and monitoring of the target IP network in a global way. [0014] The logical deployment of global network configurations according to the proposed method is based on a text-based information structured language data model, which describes the intended network configuration globally; distinguishing the present invention from others like the one described in US 2004/0117452 A1. The text-based information structured language may be the standardized XML, so the utilization of this invention by third-party applications can be flattered. Other possible text-based information structured languages to write the data model may be SGML or ASN.1. [0015] Therefore, it is an object of the invention to provide an intuitive and user-friendly mechanism for automatically configuring and reconfiguring multiple IP network topologies, involving configuration issues such as number of nodes and link connectivity, as well as remotely configuring the execution of processes at each node (e.g., routing or signalling processes). [0016] Note that for establishment and reconfiguration of a desired network topology, given the usual large size of networks (composed of several devices with different pieces of hardware, each one with its own configuration requirements), manual topology reconfiguration results in elevated time consuming and error prone complex tasks. Usually, these tasks become more critical if the network administrator has to fulfil them “by hand” using command line interfaces (CLI). [0017] In order to solve and speed up those tedious operations, another object of the invention is to allow network administrators performing a high-level specification of a target network configuration in a flexible manner, avoiding spending administration time in carrying out manual configuration node by node. [0018] The administrator or user may apply user-friendly XML existing tools to get the specification of a target IP network. Though, he/she is not required to produce directly a set of XML files, since the present invention may be integrated in a graphical user interface (GUI) just to draw the IP network scenario and logical deploy/undeploy the target network on a background IP network, including configuration and reconfiguration of the processes to be run at each node of the target IP network. [0019] In addition to the aforementioned tasks, the present invention allows monitoring the status of the already logically deployed and working network, being able to alert the administrator when any element involved in the IP network (a node, process in a node, or an interface between nodes) fails or goes wrong. [0020] More concretely, the first aspect of the invention refers to a method for logical deployment of a target IP network on a background IP network. The target IP network comprises at least one network element (NE N ; N≧1) and is supported on the background IP network formed by the at least one network element (NE N ) and at least one network elements controller (NEC Q ; Q≧1). The background IP network provides IP functional interfaces (C ik ) between the at least one network elements controller (NEC k ; k in the 1 . . . Q range) and each network element (NE i ; i=1 . . . N). This method for logical deployment of a target IP network comprises the steps of: [0000] 1 st step). Retrieving at the at least one network elements controller (NEC k ) at least one process information fragment written in the text-based information structured language (e.g. XML) for at least one of said network elements (NE i ), said at least one process information fragment defining the configuration of a network-related process. 2 nd step) Creating, at said at least one network elements controller (NEC k ), a command script for each network element (NE i ), being the command script a list of operations in terms of the functional interface (C ik ) and the operations which are to be executed in that particular network element using the respective functional interface (C ik ) by the corresponding network elements controller (NEC k ). At this step the content of the command script may be void. 3 rd step) Generating or deriving from said process information fragment at least one configuration template, for the configuration of at least one network-related process and for at least one of the network elements. 4 th step) Adding at least a command to the command script corresponding to said at least one network element, for starting each of said at least one network-related process using said configuration template. 5 th step) Pushing each of the configuration templates from the network elements controller (NEC k ) to the respective network element (NE i ); pushing means sending the configuration templates from the network elements controller (NEC k ) through the corresponding functional interfaces (C ik ) and storing said configuration templates at said corresponding network element NE i ). 6 th step) Executing the command script for said network element (NE i ) in a remote mode through the respective functional interface (C ik ) (i=1, . . . , j, . . . , N), which consists of any IP-based protocol allowing the remote executions of commands, either one-by-one or in a batch mode. [0021] The IP functional interfaces (C ik ) between a network element (NE i ) and the respective network elements controller (NEC k ) may be one of the standard protocols: RLOGIN, TELNET, SSH, TL1, RPC, RMI, XML-RPC, HTTP, SOAP, CORBA, COM+ and SNMP. [0022] Regarding configuration templates, they are defined as pieces of information that need to be pushed (sent and stored) to network elements, so that their network-related processes can work properly when they are started (for example, configuration templates contain parameters to be read by a network-related processes when started). [0023] Optionally, the method for logical deployment of the target IP network may include in the mentioned fourth step of adding commands to command scripts at said at least one network elements controller (NEC k ) further adding a command for setting an IP interface (D ij ; obviously, here i≠j, i=1 . . . N, j=1, . . . N) between two network elements (NE i , NE j ). These commands for setting an IP interface (D ij ) are added to each of the two command scripts corresponding to said two network elements (NE i , NE j ) and before the commands used for starting the network-related processes (as specified in step 4 ). In such a case, at step 6 of this method for logical deployment, it is clear that said commands are executed remotely, as part of the two corresponding scripts, through the respective functional interface (C ik , C jk ) of the network elements controller (NEC k ) with network element (NE i ) at its first end and network element (NE j ) at its second end respectively. [0024] The so-called network-related processes, to be started at the network elements (NE N ) may be selected. from a group of: routing daemons, servers, service platforms, hardware controllers, management agents, reservation protocol daemons and link resource management deamons. Some of these network-related processes needs to use the corresponding IP interface (D ij ) for their operation. There can be also network-related processes started at a network element (NE i ) that operate without involving any previous set of an IP interface (D ij ) with another network element (NE j ). [0025] In this context, a “daemon” is a process continuously running in background performing a particular, task, A “server” is a particular kind of daemon that listens for request from network clients, process them and send a response back to the client, implementing a particular service. [0026] Thus, the described method allows the configuration of all needed IP interfaces (D ij ) between pairs of network elements (NE i , NE j ), and their specification is defined as part of the target IP network. The particular information defining the IP interfaces (D ij ) depends on the particular IP connection type (direct or tunnelled), the IP networking protocol version (IPv6, IPV4), on the layer 2 or link layer aspects (Ethernet switching for Virtual Local Area Networks—VLANs—, virtual circuit technologies, etc.). [0027] Furthermore, after having a target IP network deployed according to the steps for logical deploying as described before or by another conventional method for network configuration, another aspect of the invention refers to providing in a similar intuitive way a method for logical undeployment of a target IP network comprising at least one network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) belonging to the previously deployed target IP network. [0028] This method for logical undeploying comprises the following steps: [0000] 1 st step) Retrieving at the at least one network elements controller (NEC k ) at least one process information fragment written in a text-based information structured language, for at least one of the network elements (NE i ), said at least one process information fragment defining a, network-related process; 2 nd step) Creating a command script for each of said network elements (NE i ) at one (or more if necessary) corresponding network elements controller (NEC k ), 3 th step) Adding at least a command to the command script generated at the corresponding network elements controller (NEC k ), being said commands defined for stopping each of the at least one network-related process started for at least one network element (NE i ); and 4 th step) Remotely executing through the respective functional interface (C ik ) the command script for the at least one network element (NE i ), (i=1, . . . , j, . . . , N). [0029] If an at least one IP interface (D ij ) has been specified between a pair of network elements (NE i , NE j ) in the logical deployment of the target IP network, the step of adding commands to command script at said at least one network elements controller (NEC k ) further comprising: [0030] adding a command for unsetting the IP interface (D ij ) between the network elements (NE i , NE j ) to each of the two respective command scripts and said commands are added to the command script after the ones used for stopping the network-related process (as specified in step 3 ). [0031] Another capability of this invention is a global monitoring of the target IP network. Hence, a method for logical monitoring of a target IP network is proposed here and allows a network administrator checking the status of the network-related processes for the network elements from said target IP network, which has been previously deployed by either the already described method for logical deployment or another conventional method for network configuration. The method for logical monitoring comprises the following steps, after steps of retrieving the needed process information fragments and creating new command scripts at the corresponding network elements controller (NEC k ) for each network element (NE i ) as explained before: [0032] adding at least a command to the command script generated at the corresponding network elements controller (NEC k ) for checking the status (active or inactive, running, killed, . . . ) of each of the at least one network-related process started for at least one network element (NE i ); and [0033] remotely executing through the respective functional interface (C ik ) the command script for the at least one network element (NE i ), (i=1, . . . , j, . . . , N). [0034] Additionally, the method for logical monitoring allows an administrator, if at least one IP interface (D ij ) is previously set and needed, monitoring the IP interface (D ij ) between any two network elements (NE i , NE j ). In order to check this IP interface (D ij ), ping is. performed to test Whether the particular pair of network elements (NE i , NE j ) at each end of said IP interface (D ij ) is reachable across the IP network. Thus, this method comprises the step of: [0035] at said at least one network elements controller (NEC k ), adding at least a ping command for the IP interface (D ij ) to each of the two command scripts corresponding to the two interface ending network elements (NE i , NE j ). [0036] The ping commands are added to each command script preferably before the commands used for checking the status of the network-related processes. The step for pinging further comprises sending Echo messages according to the standardized Internet Control Message Protocol (ICMP), which is one of the core protocols of the Internet protocol suite chiefly used by networked computers' operating systems to send error messages-indicating, for instance, that a requested service is not available or that a network element could not be reached. In particular, the method for monitoring performs the following message exchanges in the pinging step: [0037] sending an ICMP Echo Request message to first end of said interface (D ij ) at one of the network elements (NE i ) and listening for ICMP Echo Response message replied from said network element (NE i ) for a determined or pre-selected time, said ICMP Echo Request sent from the other network element (NE j ); and, [0000] if an ICMP Echo Response message is received from said network element (NE i ) within said determined time: [0038] sending an ICMP Echo Request message to second end of said interface (D ij ) at the other network element (NE j ) and listening for ICMP Echo Response message replied from said network element (NE j ) for a determined time (usually applying the same time constraints for both network elements), said ICMP Echo Request sent from the first end of said interface (D ij ) at corresponding network element (NE i ). [0039] There are other aspects of the present invention which refer to providing respective methods for logical deployment, undeployment and monitoring of a target IP network on a background IP network just to implement the setting, unsetting or monitoring respectively of a IP interfaces (D ij ), (i≠j). Obviously, these IP interfaces (D ij ) can be used by network-related processes that can be either configured at a pair of network elements (NE i , NE j ) of the target IP network according to the method for logical deployment described firstly or by employing another conventional method for network configuration which is suitable for managing network-related processes over the background IP network. [0040] Thus, it is provided a method for logical deployment of a target IP network on a background IP network which comprises the steps of: [0000] 1 st step) Retrieving at the at least one network elements controller (NEC k ) a IP networking information fragment written in a text-based information structured language for at least a pair of network elements (NE i , NE j ), said IP networking information fragment defining a IP networking layer (INL). The IP networking layer, also known as network layer and sometimes called the Internet layer, handles the movement of packets around the network [“TCP/IP Illustrated, Volume 1: The Protocols”, by W. Richard Stevens, Addison-Wesley, Chapter 1.2, page 2, 1994]. This layer and, more particularly, the IP networking information fragment comprises the specification of: interfaces provided by each network element (NE i ) and connection to the other network elements (NE j ) through said interfaces: here called IP interfaces (D ij ), IP address (and mask) for each one of said interfaces (D ij ). 2 nd step) Creating, at said at least one network elements controller (NEC k ), a command script for each of said network elements (NE i , NE j ). 3 th step) Adding at least a command for setting an IP interface (D ij ) between said two network elements (NE i , NE j ) to each of the command scripts corresponding to the pair of network elements (NE i , NE i ), using said IP networking information fragment, at said at least one network elements controller (NEC k ). [0043] Correspondingly, a method for logical undeployment of a target IP network is here described, said target IP network already deployed by the very previous method for logical deployment or another conventional method for IP interfaces configuration, in which at least an IP interface (D ij ) between two network elements (NE i , NE j ) has been set. This method for logical undeployment comprises steps for retrieving the IP networking information fragment at the corresponding network elements controller (NEC k ) and creating, at said at least one network elements controller (NEC k ), new command scripts for each of said network elements (NE i , NE j ), and then perform the step of: adding to each of the command scripts corresponding to the pair of network elements (NE i , NE j ) at least a command for unsetting the IP interface (D ij ). [0045] And the invention also provides with a method for logical monitoring of a target IP network already deployed in which at least an IP interface (D ij ) between two network elements (NE i , NE j ) has been previously set according to the three steps explained before for the previous method for logical monitoring or according to another conventional method for IP interfaces configuration, which allows to know whether the IP interface (D ij ) is enabled or, on the contrary, any failure occurs on reaching any of the two network elements (NE i , NE j ) across said IP interface (D ij ). In order to get such proposal, this method for logical monitoring comprising steps for retrieving the IP networking information fragment at the corresponding network elements controller (NEC k ) and creating, at said at least one network elements controller (NEC k ), new command scripts for each of said network elements (NE i , NE j ), and then perform the step of: adding to each of the command scripts created for the pair of network elements (NE i , NE j ) at least a command for pinging the IP interface (D ij ) between the two network elements (NE i , NE j )—as explained before for the pinging step—. [0047] It is another aspect of the present invention to provide a computer, program comprising computer program code means adapted to perform the steps of (any or even all of) the described methods, when said program is run on a central processing unit or processor of a computer, a general purpose processor, on a digital signal processor, a field-programmable gate array, an application-specific integrated circuit, a micro-processor, a micro-controller, or any other form of programmable hardware. [0048] It is further another aspect of the present invention to provide a network node comprising IP networking means for communication to at least another node and processing means adapted to perform the steps of any of the methods proposed. Such network node, at which any or even all of the described methods for logical deploy/undeploy/monitoring can be implemented, is what is denominated here like network elements controller (NEC), provided with means for communication with another nodes so-called network elements (NE). These network elements and network, elements controllers are nodes from an IP network, here the so-called background IP network. [0049] And it is another aspect of the present invention to provide a telecommunications network comprising at least one of these nodes acting as network elements controllers (NEC). [0050] The main advantages and innovations of the proposed invention become apparent in the description and are summarized as follows: [0051] 1. Multiple (per managed device) remote access interfaces vs. fixed explicit communication protocols: The invention described in this document neither defines a particular communication protocol, nor imposes any restriction in the communication interface of the configured elements, as a conventional management system does (like SNMP or HTTP). Instead, the present invention reuses as communication protocol any existing remote access interface the managed device is providing (like Telnet, SSH or TL1), here called as IP functional interface (C ik ). In fact, multiple remote access types can be used seamlessly, since each network element (NE i ) (managed device) can provide a different IP functional interface (C ik ) with the corresponding network elements controller (NEC k ) in the same background IP network. [0052] 2. There are no explicit agents: As explain for invention background, in the current state of the art, conventional management systems need running a dedicated process in the managed device in order to deal with the communication protocol queries from the manager and providing an interface to the device internal data and parameters. This implies complexity (different agents need to be developed, for different devices) and inefficiency (the agent process consumes resources in the managed device). On the contrary, the present invention does not use explicit agent processes, allowing the manager direct access to data and parameters through the remote access or IP functional interfaces. [0053] 3. High-level actions and module-oriented in the global network vs. low-level actions and object-oriented in individual network elements: Conventional management systems are based on atomic actions (“get”, “set”, etc.) applied to elemental data objects (for example, the IP address of the managed device) in individual network elements. Therefore, a user-oriented manager has to integrate many atomic actions to perform high-level management tasks in order to provide global network configurations and the development of such manager could be complex. The present approach is easier and more intuitive because it is based on high-level actions (deploy, undeploy and monitor) and software modules (i.e., a process) instead of low-level actions and atomic object orientation subjects. BRIEF DESCRIPTION OF THE DRAWINGS [0054] To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate a preferred embodiment of the invention, which should not be interpreted as restricting the scope of the invention, but just as an example of how the invention can be embodied. The drawings comprise the following figures: [0055] FIG. 1 is a schematic representation of a target IP network comprising a plurality of network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) supported on a background IP network composed of these gathered network elements and at least one network elements controller (NEC 1 ), in accordance with an embodiment of the present invention. [0056] FIG. 2 is a detail of the architecture of one network element (NE i ), showing the interfaces with other network elements (NE j ) and other network elements controller (NEC k ). [0057] FIG. 3 is a schematic representation of a target network configuration structure formed by XML modules from a data model, in accordance with a preferred embodiment of the present invention. [0058] FIG. 4 shows a workflow of the invention, specifying the sequence of actions that need to be performed for deploying, monitoring or un-deploying of a particular global network configuration (for instance, the target IP network from FIG. 1 ). [0059] FIG. 5 a - 5 d , put all together, represent a flowchart of a tool implemented at the network elements Controller (NEC k ) performing, in accordance with the preferred embodiment of the present invention, the steps for logical deployment (partially illustrated in FIG. 5 a ), undeployment (partially illustrated in FIG. 5 b , where the common initial step of retrieving from the data module information fragments for deploy/undeploy or monitoring is drawn), and monitoring (partially illustrated in FIG. 5 c ), being the final common step of remotely execution of commands drawn in FIG. 5 d. DETAILED DESCRIPTION OF THE INVENTION [0060] Here below a practical implementation of the invention is described, which is based on the general network architecture shown in FIG. 1 . This general network architecture gathers: several network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) connected to an IP Network ( 10 ) through a plurality of interfaces (A 1 , . . . , Ai, . . . , A j . . . , A N ), and several Network Elements Controllers (NEC 1 , . . . , NEC k , . . . , NEC Q ) connected to the same IP Network ( 10 ) through another plurality of interfaces (B 1 , . . . , B k , . . . , B Q ). [0063] These interfaces (A 1 , . . . , A N , B 1 , . . . , B Q ) on the IP Network ( 10 ) with the network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) and Network Elements. Controllers (NEC 1 , . . . , NEC k , . . . , NEC Q ) respectively could be all of the same type, for example, Ethernet interfaces. [0064] This IP Network ( 10 ) also provides a plurality of IP functional interfaces (C ik ) from each network element (NE i ) to the at least one network elements controller (NEC k ). The configuration of these functional interfaces is not provided by the invention, they are supposed pre-configured, previously to the application of the method described in this document. [0065] FIG. 1 only shows one Network Elements Controller (NEC 1 ) for the sake of clarity, but in a general, case there would be as many as desired (NEC k ), each one with its own C 1k , . . . , C Nk , interfaces. [0066] The IP Network ( 10 ) constitutes an existing background IP network over which is defined a target IP network by the multiple network elements NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) to be managed. [0067] Each network element (NE i ) has a modular architecture, as depicted in FIG. 2 , that implements an IP networking layer ( 9 ) and runs/executes several (L, with L≧0) network-related processes (P 1 , . . . , P L ). The IP networking layer ( 9 ) can be configured to provide IP interfaces (D ij ) from any of the network element (NE i ) to another one (NE j ), being i and j any non equal integers in the 1, . . . , N range. The configuration of these IP interfaces (D ij ) is provided by the method described in this document. [0068] Note that actual implementations of this invention may not implemental the possible interfaces specified in the general description. For example, in a practical implementation with four network elements maybe only four IP interfaces (for example: D 12 , D 23 , D 34 , and D 14 ) could be considered, instead of all the resting possible ones: D 13 , D 14 , D 21 , D 23 , D 24 and D 34 . [0069] An example of application could be configuration of a dynamically switched optical transport network, where the network elements are: Optical Connection Controllers (OCC) implemented in computers and constituting the control part of physical optical nodes, A Link Emulator device Ethernet Switches A router-broadband-tester with vendor-specific technology [0074] In that example, the IP functional interfaces (C ik ) are based either in SSH—for the OCCs and link emulator—, Telnet—for the switches—or RPC—provided by vendor for the router tester device—. There are three kinds of IP interfaces (D ij ): OCC-OCC directly connected through real optical fibber, OCC-OCC not using network constraints—through a dedicated VLAN—, OCC-OCC using network constraints—through link emulator device—and OCC-broadband tester—through a dedicated VLAN—. Each Optical Connection Controller runs five network-related processes (then, L=5 in this example): Optical Link Resource Manager (OLRM), Link Resource Manager (LRM), the Open Shortest Path First (OSPF) routing protocol, the Resource Reservation (RSVP) signalling protocol and SNMP management protocol. The broadband tester runs a RSVP process. [0075] Using a text-based information structured language such as XML, a global network configuration can be specified, defining a plurality of information Modules (M 0 , M 1 , . . . , M L ) that determines a target network configuration structure ( 7 ), drawn in FIG. 3 . There are process information modules (M 1 , . . . , M L ) describing each one of the L network-related processes (P 1 , . . . , P L ) along as one more information module specifying the IP networking configuration needed in the target network configuration structure ( 7 ) and here called IP networking information module (M 0 ). The present invention provides an user/administrator with means for logical deployment, of this global network configuration into the corresponding network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) using the pre-configured IP functional interfaces (C ik ) with at least one of the network elements controller (NEC 1 , . . . , NEC k , . . . , NEC Q . [0076] Each information module (M 0 , M 1 , . . . , M L ) is composed of N+1 sections: there are N sections (NE 1 sec, . . . NE i sec, . . . , NE N sec), corresponding to each one of the network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) and a global section (Gsec) including configurations elements involving several network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ). Empty sections are allowed, but each module (M 0 , M 1 , . . . , M L ) must include at least one section. [0077] A particular set of IP networking information module (M 0 ) plus process information modules (M 1 , . . . , M L ) realization consists of, for example, a set of L+1 XML files stored in the hard disk of any of the network elements controller (NEC 1 , . . . , NEC k , . . . , NEC Q ). Another implementation alternative is a group of records in a XML-based distributed database. [0078] The possible embodiments of the target network configuration structure ( 7 ) define a XML-based data model. Building, storing and retrieving of target network configurations from the XML-based data model is out of the scope of this patent. Network administrators can use any suitable XML tool or database interface, for example, a graphic user interface program or a database manager program for these purposes. [0079] The retrieved XML-based data model structured in the L+1 information modules (M 0 , M 1 , . . . , M L ) specifies the global network configurations to be deployed. The user/administrator can retrieve the needed process information fragments from the process information modules (M 1 , . . . , M L ) describing each one of the L network-related processes (P 1 , . . . , P L ) for the set of network elements at which these processes (P 1 , . . . , P L ) are required to be configured for the target network configuration. Thus, a process information fragment is a set of sections from a process information module, so also written in XML or the text-based, information language used to specify the global network configuration. Likewise, in order to configure the IP interfaces (D ij ) to be provided by the IP networking layer ( 9 ), the user/administrator can retrieve the needed IP networking fragments consisting of a set of sections from the IP networking information module (M 0 ). [0080] Each information module (M 0 , M 1 , . . . , M L ) of the XML data model conforms to a Document Type Definition or XML Schema. The Document Type Definition (DTD) is a standard language developed primarily for the expression of a schema via a set of declarations that conform to a particular markup syntax. It describes a type of documents written in a text-based information structured language (SGML, XML) in terms of constraints on the structure of those documents. XML Schema is similar to DTD, accomplishing the same purpose. Hence, the DTD/XML Schema is a description of a type of XML documents, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntax constraints imposed by XML itself. The DTD/XML Schema provides a view of the document type at a relatively high level of abstraction and is used for validation purposes during the workflow of the method for logical deployment, undeployment and monitoring described as follows and in accordance to FIG. 4 . [0081] More in detail, these information modules (M 0 , M 1 , . . . , M L ) from the XML data model include: The IP networking information module (M 0 ) with specifications of the IP networking layer ( 9 ) to support the IP interfaces (D ij ) comprises: N sections (NE 1 sec, . . . NE i sec, . . . NE N sec) including: Reference to the network element (NE i ) index (i=1 to N). The IP functional interface (C ik ) that each network elements controller (NEC 1 , . . . , NEC k , . . . , NEC Q ) uses to access the network element (NE i ). However, this is not the unique possibility and other implementations of the invention could not include the IP functional interface (C ik ) related information in the IP network information module (M 0 ). For instance, this information could be used implicitly by the software application implementing the very network elements controller (NEC k ) maybe, implemented in some configuration file or database of said network elements controller (NEC k ), which is out of the scope of this invention. A global section (Gsec) must include: The specification of all IP interfaces (D ij ) defined as part of the target IP network, depending upon the particular IP interface requirements (connection type, etc.). The process information modules (M 1 , . . . , M L ) with specifications of the network-related processes (P 1 , . . . , P L ) comprises: N sections (NE 1 sec, . . . NE i sec, . . . NE N sec) including: Reference to the network element (NE i ) index (i=1 to N). The configuration for the process running in the NE. The particular information depends on the particular process. All the necessary information regarding the process environment in network element (NE i ), for each, one of the network-related processes (P 1 , . . . , P L ); although if a particular process is not to be set in that network element (NE i ), it could be omitted. This information depends on the particular process type and the hardware platform of the network element—computer, host, router, etc.—but could include starting and stopping commands, pathname to the binary file implementing the process, location of configuration files, etc. A global section (Gsec) pet network-related processes including: Configuration elements that could affect as several process instances running in several network elements. It is up to the network administrator to use this section to include common configurations for several instances of the process in all network elements (for example, considering a dynamic routing process and supposing that all the instances uses the same routing algorithm configuration, such configuration could be defined in the global section). [0095] Given a particular XML data model to be applied to a particular IP network architecture, the actions taken for logical deploying, undeploying and monitoring that particular IP network follow the workflow of FIG. 4 : (1) Previous to the application of the corresponding method, a target network configuration must be provided by the user by means of any suitable XML tool or database interface in order to do so and it will depend on how the target network configurations are built, stored and retrieved (out of the scope of this patent). (2) User interacts with network elements controller (lets say NEC k ) in order to perform a particular action. There are three possible actions: DEPLOY, to establish the configuration in the network elements; UN-DEPLOY, to clear the configuration in the network elements, reverting the network to an un-configured state; and MONITOR, to check the status of IP interfaces (D ij ) and network-related processes in each network element (NE 1 , . . . , NE i , . . . , NE N ). In addition, the user specify the subset of the L+1 information modules: to which the action will be applied. The interface between users and network elements controller (NEC k ) is out of the scope of this patent. (3) Upon command, an engine module ( 8 ) at network elements controller (NEC k ) retrieves the required target network configuration from the XML data model. The retrieval of the target network configuration data is out of the scope of this patent. If the engine module ( 8 ) is unable to retrieve all the needed modules of the target network configuration; it reports the error to user and the workflow ends. (4) The engine module ( 8 ) processes the target network configuration, performing several actions in sequence: a. Engine ( 8 ) validates the XML data modules against DTD/XML Schema. If validation is unsuccessful, it reports the error to user and the workflow ends. b. If the validation is successful, the engine ( 8 ) generates command scripts in a per network element basis and configuration templates (in a per network element and network-related process basis). Command scripts are sequences of commands expressed in terms of the IP functional interface (C ik ) that will lead, upon execution in each network element, to the desired action (set up or deploy, set down or un-deploy, and monitor). Configuration templates are pieces of information that need to be pushed to network elements so that their network-related processes can work properly (for example, a configuration template could be a file that the process needs to read when it starts). The target network configuration must contain all the needed information and parameters (maybe implicitly) in order to build the command scripts and configuration templates needed to implement the required action (deploy, un-deploy or monitor). Otherwise, this condition is reported to the user as error and the workflow ends. (5) Configuration templates are pushed to each NE 1 , . . . , NE i , . . . NE N using the IP functional interface (C ik ) with the network elements controller (NEC k ). (6) Command scripts are executed in each NE, in a remote mode using the IP functional interface (C ik ). [0105] Finally, the user is reported on the result of the action. In the case of monitor action, this includes information about the status of the IP interfaces (D ij ) and network-related processes. [0106] The engine ( 8 ) constitute an implementation at one network elements controller (NEC k ) of the three complementing methods for logical deployment, undeployment and monitoring of a target IP network, respectively performing configuration, reconfiguration or monitoring of network-related processes (P 1 , . . . , P L ) and also the IP interfaces (D ij ) that may be used by said network-related processes (P 1 , . . . , P L ). [0107] The steps executed in the engine ( 8 ) at a network elements controller (NEC k ) follow the flowchart split in three branches corresponding to actions of logical deployment, undeployment, and monitoring, depicted in FIGS. 5 a , 5 b and 5 c respectively, altogether with a last branch that joins the previous three branches into the end of the flowchart. [0108] The step of adding commands to the command script for setting an IP interface (D ij ) between two network elements (NE i , NE j ) comprises: [0109] allocating an IP address at first end of said interface, (D ij ) at one of the network elements (NE i ); [0110] allocating an IP address at second end of said interface (D ij ) at the other network element (NE j ). [0111] If said IP interface (D ij ) between the two network elements (NE i , NE j ) is a VLAN switched Ethernet based interface, that step further comprises the operations of: [0112] establishing a VLAN identifier at first end of said interface (D ij ) at one of the network elements (NED; [0113] establishing a VLAN identifier at second end of said interface (D ij ) at the other network element (NE j ). [0114] In case that the IP interface (D ij ) between two network elements (NE i , NE j ) is implemented by means of an IP-based tunnel, such as GRE, IPSec or IP-over-IP, it is established a configuration of the two ends of said IP tunnel, said two ends corresponding to the two network elements (NE i , NE j ). [0115] In another possible case, when the target IP network is based on some virtual circuit techonology, like MPLS (Multiprotocol Label Switching), GMPLS (Generalized Multiprotocol Label Switching), ATM (Asynchronous Transfer Mode) or Frame Relay, there are more additional operations in said step in order to establish the virtual circuit or path (for example, in the case of MPLS, setting valour for label identifying the virtual circuit in the MPLS overlaid network). [0116] If establishment of the IP interface (D ij ) needs configuration in at least some other intermediate network element (NE p ) different from NE i or NE j (lets said NE p with p≠i and p≠j), said configuration is added to the command script of the at least said other intermediate network element (NE p ). This is the case when VLAN switches Ethernet based interfaces needing establish configuration in intermediate Ethernet switches or tunnel interfaces are used and so it is needed to configure all the network elements providing the tunnel. [0117] In the step of adding commands to the command script for starting network-related processes, the command added consist merely in a shell command of the operating system if UNIX or compatible operating system is running in the NE. [0118] Inversely, for logical undeployment, in the step of adding commands to the command script for stopping network-related processes, the command added can be the kill UNIX command, if UNIX or compatible operating system is running in the NE. [0119] For logical undeployment, the step of adding commands to the command script for unsetting the IP interface (D ij ) between two network elements (NE i , NE j ) further comprises: [0120] removing the IP address allocated at first end of said interface (D ij ) at one network element (NE i ); [0121] removing an IP address allocated at second end of said interface (D ij ) at the other network element (NE j ). [0122] And depending on the kind of the IP interface (D ij ), this step for unsetting said IP interface (D ij ) correspondingly includes removing the configuration of the VLAN identifiers, the two ends of the IP-based tunnel or the virtual circuit established before and, in such a case that any other intermediate, network element (NE p ) different from NE i or NE j (lets said NE p with p≠i and p≠j) is involved, removing the configuration of each intermediate network elements (NE p ) previously set to provide said IP interface (D ij ). [0123] With regards to monitoring, the step for pinging the IP interface (D ij ) between two network elements (NE i , NE j ) is based on ICMP echo messages, which are built at networking layer and then encapsulated as datagrams to be retransmitted. Hence, monitoring of IP interface (D ij ) is independent from the subjacent technology, since ping is based on IP address whose allocation is always required for setting the IP interface (D ij ), independently from its implementation—VLAN over Ethernet, GRE, IPSec or IP-over-IP, MPLS, GMPLS, ATM, Frame Relay, . . . —. [0124] Besides, in order to monitor the network-related processes (P 1 , . . . , P L ) deployed at the corresponding network element (NE i ), in the step of adding at least a command to the command script for network element (NE i ), the command added consists merely in the pidof command in case that UNIX or compatible operating system is running in the NE i . The pidof command is a UNIX utility that returns a process identifier (PID) of a running process, that is, monitoring network-related processes (P 1 , . . . , P L ) by regards to checking a particular network-related process belongs to the running process list being executed by the operating system kernel, at the network element (NE i ). [0125] Remote execution of command scripts through the IP functional interface (C ik ) depends on the type of said preconfigured IP functional interface (C ik ). For instance, if the IP functional interface (C ik ) is based on RPC or Telnet, the commands added to the command script generated at the network element controller (NEC k ) are executed one by one in sequence at the corresponding, network element (NE i ). In case of SSH, a mixed mode is applied for remote execution of command scripts, which comprises copying firstly the script file to the network element (NE i ) and, next; a command sent by network element controller (NEC k ) is executed through the SSH interface in order to execute that script file—stored in the hard disk of said network element (NE i ) or any other storing media—. In this case, being IP functional interface (C ik ) implemented as SSH, the command script are just a list of shell commands. [0126] The SSH interface can also be used to push configuration templates to the respective network element (NE i ) by copying firstly a file generated at the network element controller (NEC k ) with the configuration template derived from, the proper process information fragment P 1 , . . . , P L ) to the network element (NE i ), since SSH allows sending files from the network element controller (NEC k ) to said network element (NE i ). [0127] In this text, the term “comprises” and its derivations (such as “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc. [0128] The invention is obviously not limited to the specific embodiments described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of components, configuration, etc.), within the general scope of the invention as defined in the appended claims. [0129] Some preferred embodiments of the invention are described in the dependent claims which are included next.

The method is applied to configure, reconfigure and monitor globally a plurality of network elements (NE 1 , . . . , NE i , . . . , NE j , . . . , NE N ) connected to an IP Network ( 10 ) through multiple interfaces (A 1 , . . . , A N ), with several Network Elements Controllers (NEC 1 , . . . , NEC k , . . . , NEC Q ) connected to the same IP Network ( 10 ) through respective interfaces (B 1 , . . . , B Q ). The IP Network ( 10 ) also provides a plurality of preconfigured IP functional interfaces (C ik ) from each network element (NE i ) to the at least one network elements controller (NEC k ). Each network element (NE i ) has an IP networking layer ( 9 ) and runs/executes several net-work-related processes (P 1 , . . . , P L ) managed and monitored by this method. The method also provides configuration and monitoring of IP interfaces (D ij ) among network elements. The existing IP functional interfaces (C ik ) are used to perform such managing and monitoring. To get these aims, the method performs high-level actions instead of atomic “get/set” operations. Neither the method neither requires explicit agents-manager paradigm nor depends on a particular communication protocol for network management.