id
stringlengths 9
16
| title
stringlengths 4
335
| abstract
stringlengths 18
3.51k
| categories
listlengths 1
4
| creation_date
timestamp[ns, tz=UTC] |
|---|---|---|---|---|
1610.08228
|
Model potential for the description of metal/organic interface states
|
We present an analytical one-dimensional model potential for the description of electronic interface states that form at the interface between a metal surface and flat-lying adlayers of $\pi$-conjugated organic molecules. The model utilizes graphene as a universal representation of these organic adlayers. It predicts the energy position of the interface state as well as the overlap of its wave function with the bulk metal without free fitting parameters. We show that the interface state's energy depends systematically on the bond distance between the carbon backbone of the adayers and the metal. The general applicability and robustness of the model is demonstrated by a comparison of the calculated energies with numerous experimental results for a number of flat-lying organic molecules on different closed-packed metal surfaces that cover a large range of bond distances.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2016-10-26T08:44:57Z |
2204.13085
|
Beryllium isotopic composition and Galactic cosmic ray propagation
|
The isotopic composition of beryllium nuclei and its energy dependence encode information of fundamental importance about the propagation of cosmic rays in the Galaxy. The effects of decay on the spectrum of the unstable beryllium--10 isotope can be described introducing the average survival probability $P_{\rm surv} (E_0)$ that can inferred from measurements of the isotopic ratio Be10/Be9 if one has sufficiently good knowledge of the nuclear fragmentation cross sections that determine the isotopic composition of beryllium nuclei at injection. The average survival probability can then be interpreted in terms of propagation parameters, such as the cosmic ray average age, adopting a theoretical framework for Galactic propagation. Recently the AMS02 Collaboration has presented preliminary measurements of the beryllium isotopic composition that extend the observations to a broad energy range ($E_0 \simeq 0.7$-12 GeV/n) with small errors. In this work we discuss the average survival probability that can be inferred from the preliminary AMS02 data, adopting publically available models of the nuclear fragmentation cross sections, and interpret the results in the framework of a simple diffusion model, This study shows that the effects of decay decrease more slowly than the predictions, resulting in an average cosmic ray age that increases with energy. An alternative possibility is that the cosmic ray age distribution is broader than in the models that are now commonly accepted, suggesting that the Galactic confinement volume has a non trivial structure and is formed by an inner halo contained in an extended one.
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2022-04-27T17:30:18Z |
2102.02401
|
AtomSets -- A Hierarchical Transfer Learning Framework for Small and Large Materials Datasets
|
Predicting materials properties from composition or structure is of great interest to the materials science community. Deep learning has recently garnered considerable interest in materials predictive tasks with low model errors when dealing with large materials data. However, deep learning models suffer in the small data regime that is common in materials science. Here we leverage the transfer learning concept and the graph network deep learning framework and develop the AtomSets machine learning framework for consistent high model accuracy at both small and large materials data. The AtomSets models can work with both compositional and structural materials data. By combining with transfer learned features from graph networks, they can achieve state-of-the-art accuracy from using small compositional data (<400) to large structural data (>130,000). The AtomSets models show much lower errors than the state-of-the-art graph network models at small data limits and the classical machine learning models at large data limits. They also transfer better in the simulated materials discovery process where the targeted materials have property values out of the training data limits. The models require minimal domain knowledge inputs and are free from feature engineering. The presented AtomSets model framework opens new routes for machine learning-assisted materials design and discovery.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2021-02-04T04:02:23Z |
1803.03156
|
Perturbational non-canonical theory of molecular orbitals and its applications
|
The article contains a summary of fundamentals of the perturbational non- canonical molecular orbital (PNCMO) theory formerly developed by the author. In some respects, the PNCMO theory is a generalization of the well-known simple PMO theory: First, the usual diagonalization problem (and/or the eigenvalue equation) for a certain model Hamiltonian matrix ($\mathbf{H}$) is now replaced by two interrelated non-canonical one-electron problems, namely by the block-diagonalization problem for the matrix $\mathbf{H}$\ following from the Brillouin theorem and determining non-canonical (localized) MOs (NCMOs) and by the commutation equation for the respective one-electron density matrix (charge-bond order (CBO)) matrix. Second, perturbative solutions of the above-specified alternative problems are sought in terms of entire submatrices (blocks) of the matrix $\mathbf{H}$\ instead of usual matrix elements (e.g. of Coulomb and resonance parameters). Third, a generalized version of the perturbation theory (PT) is used in place of the standard Rayleigh-Schr\"{o}dinger PT (RSPT), wherein non-commutative quantities stand for the usual (commutative) ones (cf. the so-called non-commutative RSPT (NCRSPT)). As a result, algebraic expressions are derived for the principal quantum-chemical characteristics (including the CBO matrix, the NCMO representation matrix and the total energy) that embrace definite classes of Hamiltonian matrices and thereby of molecules. To illustrate the point, saturated and conjugated hydrocarbons are taken as examples. Arguments are given that the PNCMO theory possibly forms the basis of a novel way of qualitative chemical thinking.
|
[
"Physics Archive->physics->physics.chem-ph"
] | 2018-03-08T15:33:17Z |
2302.11869
|
The Adams differentials on the classes $h_j^3$
|
In filtration 1 of the Adams spectral sequence, using secondary cohomology operations, Adams computed the differentials on the classes $h_j$, resolving the Hopf invariant one problem. In Adams filtration 2, using equivariant and chromatic homotopy theory, Hill--Hopkins--Ravenel proved that the classes $h_j^2$ support non-trivial differentials for $j \geq 7$, resolving the celebrated Kervaire invariant one problem. The precise differentials on the classes $h_j^2$ for $j \geq 7$ and the fate of $h_6^2$ remains unknown. In this paper, in Adams filtration 3, we prove an infinite family of non-trivial $d_4$-differentials on the classes $h_j^3$ for $j \geq 6$, confirming a conjecture of Mahowald. Our proof uses two different deformations of stable homotopy theory -- $\mathbb{C}$-motivic stable homotopy theory and $\mathbb{F}_2$-synthetic homotopy theory -- both in an essential way. Along the way, we also show that $h_j^2$ survives to the Adams $E_5$-page and that $h_6^2$ survives to the Adams $E_9$-page.
|
[
"Mathematics Archive->math.AT"
] | 2023-02-23T09:15:25Z |
hep-th/9610155
|
Enhancement of Supersymmetry Near 5d Black Hole Horizon
|
Geometric Killing spinors which exist on AdS_{p+2} X S^{d-p-2} sometimes may be identified with supersymmetric Killing spinors. This explains the enhancement of unbroken supersymmetry near the p-brane horizon in d dimensions. The corresponding p-brane interpolates between two maximally supersymmetric vacua, at infinity and at the horizon. New case is studied here: p=0, d=5. The details of supersymmetric version of the very special geometry are presented. We find the area-entropy formula of the supersymmetric 5d black holes via the volume of S^3 which depends on charges and intersection matrix.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 1996-10-20T20:01:48Z |
1010.1572
|
Stationary distributions for jump processes with memory
|
We analyze a jump processes $Z$ with a jump measure determined by a "memory" process $S$. The state space of $(Z,S)$ is the Cartesian product of the unit circle and the real line. We prove that the stationary distribution of $(Z,S)$ is the product of the uniform probability measure and a Gaussian distribution.
|
[
"Mathematics Archive->math.PR"
] | 2010-09-13T10:53:39Z |
1612.01230
|
Deep Pyramidal Residual Networks with Separated Stochastic Depth
|
On general object recognition, Deep Convolutional Neural Networks (DCNNs) achieve high accuracy. In particular, ResNet and its improvements have broken the lowest error rate records. In this paper, we propose a method to successfully combine two ResNet improvements, ResDrop and PyramidNet. We confirmed that the proposed network outperformed the conventional methods; on CIFAR-100, the proposed network achieved an error rate of 16.18% in contrast to PiramidNet achieving that of 18.29% and ResNeXt 17.31%.
|
[
"Computer Science Archive->cs.CV"
] | 2016-12-05T02:41:18Z |
2008.09854
|
A variational quantum algorithm for Hamiltonian diagonalization
|
Hamiltonian diagonalization is at the heart of understanding physical properties and practical applications of quantum systems. It is highly desired to design quantum algorithms that can speedup Hamiltonian diagonalization, especially those can be implemented on near-term quantum devices. In this work, we propose a variational algorithm for Hamiltonians diagonalization (VQHD) of quantum systems, which explores the important physical properties, such as temperature, locality and correlation, of the system. The key idea is that the thermal states of the system encode the information of eigenvalues and eigenstates of the system Hamiltonian. To obtain the full spectrum of the Hamiltonian, we use a quantum imaginary time evolution algorithm with high temperature, which prepares a thermal state with a small correlation length. With Trotterization, this then allows us to implement each step of imaginary time evolution by a local unitary transformation on only a small number of sites. Diagonalizing these thermal states hence leads to a full knowledge of the Hamiltonian eigensystem. We apply our algorithm to diagonalize local Hamiltonians and return results with high precision. Our VQHD algorithm sheds new light on the applications of near-term quantum computers.
|
[
"Physics Archive->quant-ph"
] | 2020-08-22T15:20:00Z |
1507.04241
|
Radiative transfer model for contaminated slabs : experimental validations
|
This article presents a set of spectro-goniometric measurements of different water ice samples and the comparison with an approximated radiative transfer model. The experiments were done using the spectro-radiogoniometer described in Brissaud et al. (2004). The radiative transfer model assumes an isotropization of the flux after the second interface and is fully described in Andrieu et al. (2015). Two kind of experiments were conducted. First, the specular spot was closely investigated, at high angular resolution, at the wavelength of $1.5\,\mbox{\mu m}$, where ice behaves as a very absorbing media. Second, the bidirectional reflectance was sampled at various geometries, including low phase angles on 61 wavelengths ranging from $0.8\,\mbox{\mu m}$ to $2.0\,\mbox{\mu m}$. In order to validate the model, we made a qualitative test to demonstrate the relative isotropization of the flux. We also conducted quantitative assessments by using a bayesian inversion method in order to estimate the parameters (e.g. sample thickness, surface roughness) from the radiative measurements only. A simple comparison between the retrieved parameters and the direct independent measurements allowed us to validate the model. We developed an innovative bayesian inversion approach to quantitatively estimate the uncertainties on the parameters avoiding the usual slow Monte Carlo approach. First we built lookup tables, and then searched the best fits and calculated a posteriori density probability functions. The results show that the model is able to reproduce the spectral behavior of water ice slabs, as well as the specular spot. In addition, the different parameters of the model are compatible with independent measurements.
|
[
"Physics Archive->physics->physics.geo-ph"
] | 2015-07-15T14:54:23Z |
2001.05108
|
Game of Pure Chance with Restricted Boundary
|
We consider various probabilistic games with piles for one player or two players. In each round of the game, a player randomly chooses to add $a$ or $b$ chips to his pile under the condition that $a$ and $b$ are not necessarily positive. If a player has a negative number of chips after making his play, then the number of chips he collects will stay at $0$ and the game will continue. All the games we considered satisfy these rules. The game ends when one collects $n$ chips for the first time. Each player is allowed to start with $s$ chips where $s\geq 0$. We consider various cases of $(a,b)$ including the pairs $(1,-1)$ and $(2,-1)$ in particular. We investigate the probability generating functions of the number of turns required to end the games. We derive interesting recurrence relations for the sequences of such functions in $n$ and write these generating functions as rational functions. As an application, we derive other statistics for the games which include the average number of turns required to end the game and other higher moments.
|
[
"Mathematics Archive->math.CO"
] | 2020-01-15T02:37:26Z |
1905.08602
|
Time resolution and dynamic range of field effect transistor based terahertz detectors
|
We studied time resolution and response power dependence of three terahertz detectors based on significantly different types of field effect transistors. We analyzed the photoresponse of custom-made Si junctionless FETs, Si MOSFETs and GaAs-based high electron mobility transistors detectors. Applying monochromatic radiation of high power, pulsed, line-tunable molecular THz laser, which operated at frequencies in the range from 0.6-3.3 THz, we demonstrated that all these detectors have at least nanosecond response time. We showed that detectors yield a linear response in a wide range of radiation power. At high powers the response saturates varying with radiation power P as $U = R_0 P/(1+P/P_s)$, where $R_0$ is the low power responsivity, $P_s$ is the saturation power. We demonstrated that the linear part response decreases with radiation frequency increase as $R_0 \propto f^{-3}$, whereas the power at which signal saturates increases as $P_s \propto f^3$. We discussed the observed dependences in the framework of the Dyakonov-Shur mechanism and detector-antenna impedance matching. Our study showed that FET transistors can be used as ultrafast room temperature detectors of THz radiation and that their dynamic range extends over many orders of magnitude of power of incoming THz radiation. Therefore, when embedded with current driven read out electronics they are very well adopted for operation with high power pulsed sources.
|
[
"Physics Archive->physics->physics.app-ph"
] | 2019-05-21T13:17:30Z |
2209.15153
|
MonoNeuralFusion: Online Monocular Neural 3D Reconstruction with Geometric Priors
|
High-fidelity 3D scene reconstruction from monocular videos continues to be challenging, especially for complete and fine-grained geometry reconstruction. The previous 3D reconstruction approaches with neural implicit representations have shown a promising ability for complete scene reconstruction, while their results are often over-smooth and lack enough geometric details. This paper introduces a novel neural implicit scene representation with volume rendering for high-fidelity online 3D scene reconstruction from monocular videos. For fine-grained reconstruction, our key insight is to incorporate geometric priors into both the neural implicit scene representation and neural volume rendering, thus leading to an effective geometry learning mechanism based on volume rendering optimization. Benefiting from this, we present MonoNeuralFusion to perform the online neural 3D reconstruction from monocular videos, by which the 3D scene geometry is efficiently generated and optimized during the on-the-fly 3D monocular scanning. The extensive comparisons with state-of-the-art approaches show that our MonoNeuralFusion consistently generates much better complete and fine-grained reconstruction results, both quantitatively and qualitatively.
|
[
"Computer Science Archive->cs.CV"
] | 2022-09-30T00:44:26Z |
1202.5563
|
Inter-pocket pairing and gap symmetry in Fe-based superconductors with only electron pockets
|
Pairing symmetry in recently discovered Fe-based metallic superconductors AFe$_2$Se$_2$ (A = K, Rb, Cs) with high transition temperature $T_c \sim 40$ K is currently a subject of intensive debates. These systems contain only electron pockets, according to photoemission, and differ from the majority of Fe-based superconductors in which both electron and hole pockets are present. Both d-wave and s-wave pairing symmetries have been proposed for AFe$_2$Se$_2$, but a d-wave gap generally has nodes, while experiments clearly point to no-nodal behavior, and a conventional s-wave gap is inconsistent with the observation of the neutron resonance below $T_c$. We argue that current theories of pairing in such systems are incomplete and must include not only intra-pocket pairing condensate but also inter-pocket condensate made of fermions belonging to different electron pockets. We analyze the interplay between intra-pocket and inter-pocket pairing depending on the ellipticity of electron pockets and the strength of their hybridization and show that hybridization brings the system into a new $s^{+-}$ state, in which the gap changes sign between hybridized pockets. This state has the full gap and at the same time supports spin resonance, in agreement with the data. Near the boundary of $s^{+-}$ state we found a long-thought $s+id$ state which breaks time-reversal symmetry.
|
[
"Physics Archive->cond-mat->cond-mat.str-el",
"Physics Archive->cond-mat->cond-mat.supr-con"
] | 2012-02-24T21:26:47Z |
1302.2608
|
A Stochastic Method for Computing Hadronic Matrix Elements
|
We present a stochastic method for the calculation of baryon three-point functions that is more versatile compared to the typically used sequential method. We analyze the scaling of the error of the stochastically evaluated three-point function with the lattice volume and find a favorable signal-to-noise ratio suggesting that our stochastic method can be used efficiently at large volumes to compute hadronic matrix elements.
|
[
"Physics Archive->hep->hep-lat"
] | 2013-02-11T20:49:05Z |
0709.3703
|
Decay Rates for Spherical Scalar Waves in the Schwarzschild Geometry
|
The Cauchy problem is considered for the scalar wave equation in the Schwarzschild geometry. Using an integral spectral representation we derive the exact decay rate for solutions of the Cauchy problem with spherical symmetric initial data, which is smooth and compactly supported outside the event horizon.
|
[
"Physics Archive->gr-qc"
] | 2007-09-24T08:07:17Z |
1410.0971
|
Orbital occupancy and charge doping in iron-based superconductors
|
Iron-based superconductors (FBS) comprise several families of compounds having the same atomic building blocks for superconductivity, but large discrepancies among their physical properties. A longstanding goal in the field has been to decipher the key underlying factors controlling TC and the various doping mechanisms. In FBS materials this is complicated immensely by the different crystal and magnetic structures exhibited by the different families. In this paper, using aberration-corrected scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS), we observe a universal behavior in the hole concentration and magnetic moment across different families. All the parent materials have the same total number of electrons in the Fe 3d bands; however, the local Fe magnetic moment varies due to different orbital occupancy. Although the common understanding has been that both long-range and local magnetic moments decrease with doping, we find that, near the onset of superconductivity, the local magnetic moment increases and shows a dome-like maximum near optimal doping, where no ordered magnetic moment is present. In addition, we address a longstanding debate concerning how Co substitutions induces superconductivity in the 122 arsenide family, showing that the 3d band filling increases a function of doping. These new microscopic insights into the properties of FBS demonstrate the importance of spin fluctuations for the superconducting state, reveal changes in orbital occupancy among different families of FBS, and confirm charge doping as one of the mechanisms responsible for superconductivity in 122 arsenides.
|
[
"Physics Archive->cond-mat->cond-mat.supr-con"
] | 2014-10-03T20:18:59Z |
1912.04070
|
Synthetic Humans for Action Recognition from Unseen Viewpoints
|
Although synthetic training data has been shown to be beneficial for tasks such as human pose estimation, its use for RGB human action recognition is relatively unexplored. Our goal in this work is to answer the question whether synthetic humans can improve the performance of human action recognition, with a particular focus on generalization to unseen viewpoints. We make use of the recent advances in monocular 3D human body reconstruction from real action sequences to automatically render synthetic training videos for the action labels. We make the following contributions: (i) we investigate the extent of variations and augmentations that are beneficial to improving performance at new viewpoints. We consider changes in body shape and clothing for individuals, as well as more action relevant augmentations such as non-uniform frame sampling, and interpolating between the motion of individuals performing the same action; (ii) We introduce a new data generation methodology, SURREACT, that allows training of spatio-temporal CNNs for action classification; (iii) We substantially improve the state-of-the-art action recognition performance on the NTU RGB+D and UESTC standard human action multi-view benchmarks; Finally, (iv) we extend the augmentation approach to in-the-wild videos from a subset of the Kinetics dataset to investigate the case when only one-shot training data is available, and demonstrate improvements in this case as well.
|
[
"Computer Science Archive->cs.CV"
] | 2019-12-09T14:17:03Z |
1802.03158
|
Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV $pp$ collisions with the ATLAS detector
|
A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$ recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95% confidence-level upper limits of between 0.083 fb and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.
|
[
"Physics Archive->hep->hep-ex"
] | 2018-02-09T07:43:47Z |
2203.11074
|
Distributed Stochastic Compositional Optimization Problems over Directed Networks
|
We study the distributed stochastic compositional optimization problems over directed communication networks in which agents privately own a stochastic compositional objective function and collaborate to minimize the sum of all objective functions. We propose a distributed stochastic compositional gradient descent method, where the gradient tracking and the stochastic correction techniques are employed to adapt to the networks' directed structure and increase the accuracy of inner function estimation. When the objective function is smooth, the proposed method achieves the convergence rate $\mathcal{O}\left(k^{-1/2}\right)$ and sample complexity $\mathcal{O}\left(\frac{1}{\epsilon^2}\right)$ for finding the ($\epsilon$)-stationary point. When the objective function is strongly convex, the convergence rate is improved to $\mathcal{O}\left(k^{-1}\right)$. Moreover, the asymptotic normality of Polyak-Ruppert averaged iterates of the proposed method is also presented. We demonstrate the empirical performance of the proposed method on model-agnostic meta-learning problem and logistic regression problem.
|
[
"Mathematics Archive->math.OC"
] | 2022-03-21T15:55:22Z |
solv-int/9710020
|
The Painlev\'e approach to nonlinear ordinary differential equations
|
The ``Painlev\'e analysis'' is quite often perceived as a collection of tricks reserved to experts. The aim of this course is to demonstrate the contrary and to unveil the simplicity and the beauty of a subject which is in fact the theory of the (explicit) integration of nonlinear differential equations. To achieve our goal, we will not start the exposition with a more or less precise ``Painlev\'e test''. On the contrary, we will finish with it, after a gradual introduction to the rich world of singularities of nonlinear differential equations, so as to remove any cooking recipe. The emphasis is put on embedding each method of the test into the well known theorem of perturbations of Poincar\'e. A summary can be found at the beginning of each chapter.
|
[
"Physics Archive->nlin->nlin.SI"
] | 1997-10-24T13:53:45Z |
1802.03927
|
Conductance scaling of junctions of Luttinger-liquid wires out of equilibrium
|
We develop the renormalization group theory of the conductances of N-lead junctions of spinless Luttinger-liquid wires as functions of bias voltages applied to N independent Fermi-liquid reservoirs. Based on the perturbative results up to second order in the interaction we demonstrate that the conductances obey scaling. The corresponding renormalization group $\beta$ functions are derived up to second order.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2018-02-12T08:16:20Z |
1609.05777
|
Polarization-tailored Fano interference in plasmonic crystals: A Mueller matrix model of anisotropic Fano resonance
|
We present a simple yet elegant Mueller matrix approach for controlling the Fano interference effect and engineering the resulting asymmetric spectral line shape in anisotropic optical system. The approach is founded on a generalized model of anisotropic Fano resonance, which relates the spectral asymmetry to two physically meaningful and experimentally accessible parameters of interference, namely, the Fano phase shift and the relative amplitudes of the interfering modes. The differences in these parameters between orthogonal linear polarizations in an anisotropic system are exploited to desirably tune the Fano spectral asymmetry using pre- and post-selection of optimized polarization states. Experimental control on the Fano phase and the relative amplitude parameters and resulting tuning of spectral asymmetry is demonstrated in waveguided plasmonic crystals using Mueller matrix-based polarization analysis. The approach enabled tailoring of several exotic regimes of Fano resonance including the complete reversal of the spectral asymmetry. The demonstrated control and the ensuing large tunability of Fano resonance in anisotropic systems shows potential for Fano resonance-based applications involving control and manipulation of electromagnetic waves at the nano scale.
|
[
"Physics Archive->physics->physics.optics"
] | 2016-09-19T15:25:53Z |
2203.00548
|
An Adaptable and Agnostic Flow Scheduling Approach for Data Center Networks
|
Cloud applications have reshaped the model of services and infrastructure of the Internet. Search engines, social networks, content delivery and retail and e-commerce sites belong to this group of applications. An important element in the architecture of data centers where these applications run is the communication infrastructure, commonly known as data center networks (DCNs). A critical challenge DCNs have to address is the processing of the traffic of cloud applications, which due to its properties is essentially different to the traffic of other Internet applications. In order to improve the responsiveness and throughput of applications, DCNs should be able to prioritize short flows (a few KB) over long flows (several MB). However, given the time and space variations the traffic presents, the information about flow sizes is not available in advance in order to plan the flow scheduling. In this paper, we present an adaptable mechanism called Adaptable Workload-Agnostic Flow Scheduling (AWAFS). It is an adaptable approach that can adjust in an agnostic way the scheduling configuration of DCN forwarding devices. This agnostic adjustment contributes to reduce the Flow Completion Time (FCT) of those short flows, representing around 85% of the traffic handled by cloud applications. Our evaluation results based on simulation show that AWAFS can reduce the average FCT of short flows between 16.9% and 45.2% when compared to the best existing agnostic non-adaptable solution, without inducing starvation on long flows. Indeed, it can provide improvements as high as 39% for long flows. Additionally, AWAFS can improve the FCT for short flows in scenarios with high heterogeneity in the traffic present in the network, with a reduction up to 5% for the average FCT and 15% for the tail FCT.
|
[
"Computer Science Archive->cs.NI"
] | 2022-03-01T15:31:10Z |
2112.00585
|
Neural Emotion Director: Speech-preserving semantic control of facial expressions in "in-the-wild" videos
|
In this paper, we introduce a novel deep learning method for photo-realistic manipulation of the emotional state of actors in "in-the-wild" videos. The proposed method is based on a parametric 3D face representation of the actor in the input scene that offers a reliable disentanglement of the facial identity from the head pose and facial expressions. It then uses a novel deep domain translation framework that alters the facial expressions in a consistent and plausible manner, taking into account their dynamics. Finally, the altered facial expressions are used to photo-realistically manipulate the facial region in the input scene based on an especially-designed neural face renderer. To the best of our knowledge, our method is the first to be capable of controlling the actor's facial expressions by even using as a sole input the semantic labels of the manipulated emotions, while at the same time preserving the speech-related lip movements. We conduct extensive qualitative and quantitative evaluations and comparisons, which demonstrate the effectiveness of our approach and the especially promising results that we obtain. Our method opens a plethora of new possibilities for useful applications of neural rendering technologies, ranging from movie post-production and video games to photo-realistic affective avatars.
|
[
"Computer Science Archive->cs.CV"
] | 2021-12-01T15:55:04Z |
1301.2963
|
A(4) Flavor Symmetry Model for Dirac-Neutrinos and Sizable U(e3)
|
Models based on flavor symmetries are the most often studied approaches to explain the unexpected structure of lepton mixing. In many flavor symmetry groups a product of two triplet representations contains a symmetric and an anti-symmetric term. If this product of two triplets corresponds to a Majorana mass term, then the anti-symmetric part vanishes, and in economic models tri-bimaximal mixing is achieved. If neutrinos are Dirac particles, the anti-symmetric part is however present and leads to deviations from tri-bimaximal mixing, in particular non-zero U(e3). Thus, the non-vanishing value of U(e3) and the nature of the neutrino are connected. We illustrate this with a model based on A(4) within the framework of a neutrinophilic 2 Higgs doublet scenario.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2013-01-14T13:06:11Z |
1805.05952
|
Magnetosphere of a spinning black hole and the role of the current sheet
|
We revisit the problem of a spinning black hole immersed in a uniformly magnetized plasma within the context of force-free electrodynamics. Such configurations have been found to relax to stationary jetlike solutions that are powered by the rotational energy of the black hole. We write down an analytic description for the jet solutions in the low black hole spin limit, and demonstrate that it provides a good approximation to the configurations found dynamically. For characterizing the magnetospheres of rapidly spinning black holes, we find that the current sheet which forms in the black hole ergosphere plays an essential role. We study the properties of the current sheet, and its importance in determining the jet solution and the rate at which energy is extracted from the black hole.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->gr-qc"
] | 2018-05-15T18:00:00Z |
1905.06627
|
Reasoning about Cognitive Trust in Stochastic Multiagent Systems
|
We consider the setting of stochastic multiagent systems modelled as stochastic multiplayer games and formulate an automated verification framework for quantifying and reasoning about agents' trust. To capture human trust, we work with a cognitive notion of trust defined as a subjective evaluation that agent A makes about agent B's ability to complete a task, which in turn may lead to a decision by A to rely on B. We propose a probabilistic rational temporal logic PRTL*, which extends the probabilistic computation tree logic PCTL* with reasoning about mental attitudes (beliefs, goals and intentions), and includes novel operators that can express concepts of social trust such as competence, disposition and dependence. The logic can express, for example, that `agent A will eventually trust agent B with probability at least p that B will behave in a way that ensures the successful completion of a given task'. We study the complexity of the automated verification problem and, while the general problem is undecidable, we identify restrictions on the logic and the system that result in decidable, or even tractable, subproblems.
|
[
"Computer Science Archive->cs.LO"
] | 2019-05-16T09:54:09Z |
hep-ph/9607408
|
QCD Sum Rule Calculation for the Tensor Charge of the Nucleon
|
The nucleon's tensor charges (isovector $g^v_T={\delta}u-{\delta}d$ and isoscalar $g^s_T={\delta}u+{\delta}d$) are calculated using the QCD sum rules in the presence of an external tensor field. In addition to the standard quark and gluon condensates, new condensates described by vacuum susceptibilities are induced by the external field. The latter contributions to $g^v_T$ and $g^s_T$ are estimated to be small. After deriving some simplifying formulas, a detailed sum rule analysis yields $g^v_T=1.29 \pm 0.51$ and $g^s_T = 1.37 \pm 0.55$, or ${\delta}u=1.33 \pm 0.53$ and ${\delta}d = 0.04 \pm 0.02$ at the scale of 1 GeV$^2$.
|
[
"Physics Archive->hep->hep-ph"
] | 1996-07-23T17:58:37Z |
1207.3303
|
The two dimensional harmonic oscillator on a noncommutative space with minimal uncertainties
|
The two dimensional set of canonical relations giving rise to minimal uncertainties previously constructed from a q-deformed oscillator algebra is further investigated. We provide a representation for this algebra in terms of a flat noncommutative space and employ it to study the eigenvalue spectrum for the harmonic oscillator on this space. The perturbative expression for the eigenenergy indicates that the model might possess an exceptional point at which the spectrum becomes complex and its PT-symmetry is spontaneously broken.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->hep->hep-th",
"Physics Archive->math-ph",
"Physics Archive->quant-ph"
] | 2012-07-13T16:56:06Z |
nucl-th/0101010
|
Phenomenology of kaonic atoms and other strange hadronic atoms
|
Recent optical-potential studies of the phenomenology of kaonic atoms are reviewed. It is shown that the data can be fitted by a complex optical potential with either a relatively shallow attractive component (about -50 MeV at nuclear-matter density), as suggested by a self consistent application of chirally motivated coupled-channels models, or a relatively deep attractive component (about -180 MeV at nuclear-matter density) as suggested by a mean-field extrapolation of a phenomenological low-density expansion. Both classes of these optical potentials, due to their strongly absorptive component, predict similarly structured relatively narrow `deeply bound' kaonic-atom states with widths saturating at about 2 MeV. Possible formation reactions are briefly discussed. The more speculative case for relatively narrow deeply bound kaonic nuclear states is briefly mentioned. Recent works on other strange hadronic atom systems, for the negatively charged Sigma and Cascade hyperons, are also discussed.
|
[
"Physics Archive->nucl->nucl-th"
] | 2001-01-03T15:28:39Z |
1703.06830
|
Positive $L^p$-bounded Dunkl-type generalized translation operator and its applications
|
We prove that the spherical mean value of the Dunkl-type generalized translation operator $\tau^y$ is a positive $L^p$-bounded generalized translation operator $T^t$. As application, we prove the Young inequality for a convolution defined by $T^t$, the $L^p$-boundedness of $\tau^y$ on a radial functions for $p>2$, the $L^p$-boundedness of the Riesz potential for the Dunkl transform and direct and inverse theorems of approximation theory in $L^p$-spaces with the Dunkl weight.
|
[
"Mathematics Archive->math.CA"
] | 2017-03-20T16:30:02Z |
2307.01562
|
Facteurs disjoints des transformations melangeantes
|
We show that any non-mixing automorphism of a standard probability space has a factor disjoint from all mixing automorphism.
|
[
"Mathematics Archive->math.DS"
] | 2023-07-04T08:32:18Z |
1810.00372
|
On the scattering of a high-energy cosmic ray electrons off the dark matter
|
High-energy cosmic ray electrons interaction with Dark Matter particles are considered. In particular, a weakening of energy spectrum of cosmic electrons is predicted resulting from inelastic electron scattering on hyper-pions in the hypercolor extension of the Standard Model. Corresponding cross section and angular distributions of secondary neutrino are calculated and studied. We also briefly discuss some effects of scattering processes of such type.
|
[
"Physics Archive->hep->hep-ph"
] | 2018-09-30T13:24:39Z |
1708.00201
|
An extinction free AGN selection by 18-band SED fitting in mid-infrared in the AKARI NEP deep field
|
We have developed an efficient Active Galactic Nucleus (AGN) selection method using 18-band Spectral Energy Distribution (SED) fitting in mid-infrared (mid-IR). AGNs are often obscured by gas and dust, and those obscured AGNs tend to be missed in optical, UV and soft X-ray observations. Mid-IR light can help us to recover them in an obscuration free way using their thermal emission. On the other hand, Star-Forming Galaxies (SFG) also have strong PAH emission features in mid-IR. Hence, establishing an accurate method to separate populations of AGN and SFG is important. However, in previous mid-IR surveys, only 3 or 4 filters were available, and thus the selection was limited. We combined AKARI's continuous 9 mid-IR bands with WISE and Spitzer data to create 18 mid-IR bands for AGN selection. Among 4682 galaxies in the AKARI NEP deep field, 1388 are selected to be AGN hosts, which implies an AGN fraction of 29.6$\pm$0.8$\%$ (among them 47$\%$ are Seyfert 1.8 and 2). Comparing the result from SED fitting into WISE and Spitzer colour-colour diagram reveals that Seyferts are often missed by previous studies. Our result has been tested by stacking median magnitude for each sample. Using X-ray data from Chandra, we compared the result of our SED fitting with WISE's colour box selection. We recovered more X-ray detected AGN than previous methods by 20$\%$.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | 2017-08-01T08:32:29Z |
hep-th/9801190
|
D-brane conformal field theory
|
We outline the structure of boundary conditions in conformal field theory. A boundary condition is specified by a consistent collection of reflection coefficients for bulk fields on the disk together with a choice of an automorphism \omega of the fusion rules that preserves conformal weights. Non-trivial automorphisms \omega correspond to D-brane configurations for arbitrary conformal field theories.
|
[
"Physics Archive->hep->hep-th"
] | 1998-01-28T13:15:00Z |
physics/0512192
|
Monte Carlo based studies of a polarized positron source for International Linear Collider (ILC)
|
The full exploitation of the physics potential of an International Linear Collider (ILC) requires the development of a polarized positron beam. New concepts of polarized positron sources are based on the development of circularly polarized photon sources. The polarized photons create electron-positron pairs in a thin target and transfer their polarization state to the outgoing leptons. To achieve a high level of positron polarization the understanding of the production mechanisms in the target is crucial. Therefore a general framework for the simulation of polarized processes with GEANT4 is under development. In this contribution the current status of the project and its application to a study of the positron production process for the ILC is presented.
|
[
"Physics Archive->physics->physics.ins-det"
] | 2005-12-21T09:49:42Z |
1511.04234
|
Spray formation: a numerical closeup
|
Spray formation and atomization in a gas-liquid mixing layer is an important fundamental problem of multiphase flows. It is highly desirable to visualize the detailed atomization process and to analyze the instabilities and mechanisms involved, and massive numerical simulations are required, in addition to experiment. Rapid development of numerical methods and computer technology in the past decades now allows large-scale three-dimensional direct numerical simulations of atomization to be performed. Nevertheless, the fundamental question, whether all the physical scales involved in the primary breakup process are faithfully resolved, remains unclear. In the present study, we conduct direct numerical simulations of spray formation in a gas-liquid mixing layer with state-of-the-art computational resources (using up to 4 billion cells and 16384 cores), in order to obtain a high-fidelity numerical closeup of the detailed mechanisms of spray formation. We also aim to examine whether present computational resources are sufficient for a fully resolved direct numerical simulation of atomization.
|
[
"Physics Archive->physics->physics.flu-dyn"
] | 2015-11-13T11:05:36Z |
cond-mat/0611050
|
Simulations for trapping reactions with subdiffusive traps and subdiffusive particles
|
While there are many well-known and extensively tested results involving diffusion-limited binary reactions, reactions involving subdiffusive reactant species are far less understood. Subdiffusive motion is characterized by a mean square displacement $<x^2> \sim t^\gamma$ with $0<\gamma<1$. Recently we calculated the asymptotic survival probability $P(t)$ of a (sub)diffusive particle ($\gamma^\prime$) surrounded by (sub)diffusive traps ($\gamma$) in one dimension. These are among the few known results for reactions involving species characterized by different anomalous exponents. Our results were obtained by bounding, above and below, the exact survival probability by two other probabilities that are asymptotically identical (except when $\gamma^\prime=1$ and $0<\gamma<2/3$). Using this approach, we were not able to estimate the time of validity of the asymptotic result, nor the way in which the survival probability approaches this regime. Toward this goal, here we present a detailed comparison of the asymptotic results with numerical simulations. In some parameter ranges the asymptotic theory describes the simulation results very well even for relatively short times. However, in other regimes more time is required for the simulation results to approach asymptotic behavior, and we arrive at situations where we are not able to reach asymptotia within our computational means. This is regrettably the case for $\gamma^\prime=1$ and $0<\gamma<2/3$, where we are therefore not able to prove or disprove even conjectures about the asymptotic survival probability of the particle.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2006-11-02T10:39:39Z |
astro-ph/0501251
|
Overview on direct and indirect measurements of cosmic rays - Some thoughts on galactic cosmic rays and the knee
|
An overview is given on results from direct and indirect measurements of galactic cosmic rays. Their implications on the contemporary understanding of the origin of cosmic rays and the knee in their energy spectrum are discussed.
|
[
"Physics Archive->astro-ph"
] | 2005-01-13T13:41:17Z |
2107.00305
|
Normalizers and centralizers of $p$-subgroups in normal subsystems of fusion systems
|
Suppose $\mathcal{E}$ is a normal subsystem of a saturated fusion system $\mathcal{F}$ over $S$. If $X\leq S$ is fully $\mathcal{F}$-normalized, then Aschbacher defined a normal subsystem $N_{\mathcal{E}}(X)$ of $N_{\mathcal{F}}(X)$. In this short note we revisit and generalize this result using the theory of localities. Our more general approach leads in particular to a normal subsystem $C_{\mathcal{E}}(X)$ of $C_{\mathcal{F}}(X)$ for every $X\leq S$ which is fully $\mathcal{F}$-centralized.
|
[
"Mathematics Archive->math.GR"
] | 2021-07-01T08:51:29Z |
cond-mat/0610044
|
Nonlinear effects in spin relaxation of cavity polaritons
|
We present the general kinetic formalism for the description of spin and energy relaxation of the cavity polaritons in the framework of the Born-Markov approximation. All essential mechanisms of polaritons redistribution in reciprocal space together with final state bosonic stimulation are taken into account, from our point of view. The developed theory is applied to describe our experimental results on the polarization dynamics obtained in the polariton parametric amplifier geometry (pumping at so-called magic angle). We have experimentally confirmed that the anisotropy of the polariton-polariton interaction is responsible for the build up of the cross-linear polarisation of the signal. The long-living linear polarization is observed at zero detuning. Under elliptical pumping, we have directly measured in the time domain and modelled the effect of self-induced Larmor precession.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->cond-mat->cond-mat.other"
] | 2006-10-02T16:17:21Z |
2110.03511
|
Peer Collaborative Learning for Polyphonic Sound Event Detection
|
This paper describes that semi-supervised learning called peer collaborative learning (PCL) can be applied to the polyphonic sound event detection (PSED) task, which is one of the tasks in the Detection and Classification of Acoustic Scenes and Events (DCASE) challenge. Many deep learning models have been studied to find out what kind of sound events occur where and for how long in a given audio clip. The characteristic of PCL used in this paper is the combination of ensemble-based knowledge distillation into sub-networks and student-teacher model-based knowledge distillation, which can train a robust PSED model from a small amount of strongly labeled data, weakly labeled data, and a large amount of unlabeled data. We evaluated the proposed PCL model using the DCASE 2019 Task 4 datasets and achieved an F1-score improvement of about 10% compared to the baseline model.
|
[
"Computer Science Archive->cs.LG",
"Computer Science Archive->cs.SD",
"Electrical Engineering and Systems Science Archive->eess.AS"
] | 2021-10-07T14:47:11Z |
2010.14415
|
Measurements of $e^+e^-\rightarrow \eta_{\rm c}\pi^+ \pi^-\pi^0$, $\eta_{\rm c}\pi^+ \pi^-$ and $\eta_{\rm c}\pi^0\gamma$ at $\sqrt{s}$ from 4.18 to 4.60\,GeV, and search for a $Z_{\rm c}$ state close to the $D\bar{D}$ threshold decaying to $\eta_{\rm c}\pi$ at $\sqrt{s}$ = 4.23 GeV
|
We study $\eta_{\rm c}$ production at center-of-mass energies $\sqrt{s}$ from 4.18 to 4.60 GeV in $e^+e^-$ annihilation data collected with the BESIII detector operating at the BEPCII storage ring, corresponding to 7.3 fb$^{-1}$ of integrated luminosity. We measure the cross sections of the three different exclusive reactions $e^+e^-\rightarrow \eta_{\rm c}\pi^+ \pi^-\pi^0$, $e^+e^- \rightarrow \eta_{\rm c}\pi^+ \pi^-$, and $e^+e^- \rightarrow \eta_{\rm c}\pi^0\gamma$. We find significant $\eta_{\rm c}$ production in $e^+e^-\rightarrow \eta_{\rm c}\pi^+ \pi^-\pi^0$ at $\sqrt{s}$ of 4.23 GeV and 4.26 GeV and observe a significant energy-dependent Born cross section that we measure to be consistent with the production via the intermediate $Y(4260)$ resonance. In addition, we perform a search for a charmonium-like $Z_{\rm c}$ state close to the $D\bar{D}$ threshold that decays to $\eta_{\rm c}\pi$, involving ground state charmonium, and observe no signal. Corresponding upper limits on the cross section of $\eta_{\rm c}$ and $Z_{\rm c}$ production are provided, where the yields are not found to be significant.
|
[
"Physics Archive->hep->hep-ex"
] | 2020-10-27T16:24:15Z |
2201.11817
|
Modeling Human Exploration Through Resource-Rational Reinforcement Learning
|
Equipping artificial agents with useful exploration mechanisms remains a challenge to this day. Humans, on the other hand, seem to manage the trade-off between exploration and exploitation effortlessly. In the present article, we put forward the hypothesis that they accomplish this by making optimal use of limited computational resources. We study this hypothesis by meta-learning reinforcement learning algorithms that sacrifice performance for a shorter description length (defined as the number of bits required to implement the given algorithm). The emerging class of models captures human exploration behavior better than previously considered approaches, such as Boltzmann exploration, upper confidence bound algorithms, and Thompson sampling. We additionally demonstrate that changing the description length in our class of models produces the intended effects: reducing description length captures the behavior of brain-lesioned patients while increasing it mirrors cognitive development during adolescence.
|
[
"Computer Science Archive->cs.LG"
] | 2022-01-27T21:49:52Z |
2012.04499
|
Toroidalization of Locally Toroidal Morphisms
|
The problem of toroidalization is to construct a toroidal lifting of a dominant morphism $\varphi:X\to Y$ of algebraic varieties by blowing up in the target and domain. This paper contains a solution to this problem when $\varphi$ is locally toroidal.
|
[
"Mathematics Archive->math.AG"
] | 2020-12-08T15:37:21Z |
2303.11317
|
Grover's Algorithm Offers No Quantum Advantage
|
Grover's algorithm is one of the primary algorithms offered as evidence that quantum computers can provide an advantage over classical computers. It involves an "oracle" (external quantum subroutine) which must be specified for a given application and whose internal structure is not part of the formal scaling of the quantum speedup guaranteed by the algorithm. Grover's algorithm also requires exponentially many steps to succeed, raising the question of its implementation on near-term, non-error-corrected hardware and indeed even on error-corrected quantum computers. In this work, we construct a quantum inspired algorithm, executable on a classical computer, that performs Grover's task in a linear number of call to the oracle - an exponentially smaller number than Grover's algorithm - and demonstrate this algorithm explicitly for boolean satisfiability problems (3-SAT). Our finding implies that there is no a priori theoretical quantum speedup associated with Grover's algorithm. We critically examine the possibility of a practical speedup, a possibility that depends on the nature of the quantum circuit associated with the oracle. We argue that the unfavorable scaling of the success probability of Grover's algorithm, which in the presence of noise decays as the exponential of the exponential of the number of qubits, makes a practical speedup unrealistic even under extremely optimistic assumptions on both hardware quality and availability.
|
[
"Physics Archive->cond-mat->cond-mat.str-el",
"Physics Archive->quant-ph"
] | 2023-03-20T17:56:20Z |
1202.0799
|
Espaces de Berkovich sur Z : \'etude locale
|
We investigate the local properties of Berkovich spaces over Z. Using Weierstrass theorems, we prove that the local rings of those spaces are noetherian, regular in the case of affine spaces and excellent. We also show that the structure sheaf is coherent. Our methods work over other base rings (valued fields, discrete valuation rings, rings of integers of number fields, etc.) and provide a unified treatment of complex and p-adic spaces.
|
[
"Mathematics Archive->math.AG",
"Mathematics Archive->math.NT"
] | 2012-02-03T19:07:51Z |
1103.4860
|
Unifying N=5 and N=6
|
We write the Lagrangian of the general N=5 three-dimensional superconformal Chern-Simons theory, based on a basic Lie superalgebra, in terms of our recently introduced N=5 three-algebras. These include N=6 and N=8 three-algebras as special cases. When we impose an antisymmetry condition on the triple product, the supersymmetry automatically enhances, and the N=5 Lagrangian reduces to that of the well known N=6 theory, including the ABJM and ABJ models.
|
[
"Mathematics Archive->math.QA",
"Physics Archive->hep->hep-th"
] | 2011-03-24T20:00:04Z |
2311.14629
|
Light New Physics in $B\to K^{(*)}\nu\bar\nu$?
|
The study of the rare decays $B\to K^{(*)} \nu \bar\nu$ offers a window into the dynamics operating at the electroweak scale, allowing studies of the Standard Model and searches for heavy new physics. However, the analysis of these decays is also potentially sensitive to the on-shell production of new light bosons $X$ through the process $B\to K^{(*)} X$. In particular, Belle~II has recently measured $B^+\to K^+\nu\bar\nu$, finding a $2.8\sigma$ excess under the assumption of heavy new physics. Since this excess is rather localized in the kaon energy, a fit that includes the decay mode $B^+\to K^+ X$ to the kinematic distributions prefers $m_X\approx2\,$GeV with branching fraction Br$[B\to KX]=(8.8\pm2.5)\times 10^{-6}$ and a significance of $\approx3.6\sigma$. However, no excess was found in the BaBar measurements of $B\to K^{(*)} \nu \bar\nu$, and a global analysis of the Belle II and BaBar data leads to Br$[B\to KX]=(5.1\pm2.1)\times 10^{-6}$ with a reduced significance of $\approx2.4\sigma$. We then study various simplified dark-flavoured models and present a possible UV completion based on a gauged $B_3-L_3$ symmetry, highlighting the discovery potential of dedicated searches for $B\to K^{(*)}X$ at Belle II.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2023-11-24T17:48:20Z |
2011.14392
|
GitHub-OSS Fixit: Fixing bugs at scale in a Software Engineering Course
|
Many studies have shown the benefits of introducing open-source projects into teaching Software Engineering (SE) courses. However, there are several limitations of existing studies that limit the wide adaptation of open-source projects in a classroom setting, including (1) the selected project is limited to one particular project, (2) most studies only investigated on its effect on teaching a specific SE concept, and (3) students may make mistakes in their contribution which leads to poor quality code. Meanwhile, software companies have successfully launched programs like Google Summer of Code (GSoC) and FindBugs "fixit" to contribute to open-source projects. Inspired by the success of these programs, we propose GitHub-OSS Fixit, a course project where students are taught to contribute to open-source Java projects by fixing bugs reported in GitHub. We described our course outline to teach students SE concepts by encouraging the usages of several automated program analysis tools. We also included the carefully designed instructions that we gave to students for participating in GitHub-OSS Fixit. As all lectures and labs are conducted online, we think that our course design could help in guiding future online SE courses. Overall, our survey results show that students think that GitHub-OSS Fixit could help them to improve many skills and apply the knowledge taught in class. In total, 154 students have submitted 214 pull requests to 24 different Java projects, in which 59 of them have been merged, and 82 have been closed by developers.
|
[
"Computer Science Archive->cs.SE"
] | 2020-11-29T16:00:43Z |
0908.1990
|
Discovery of the Extremely Energetic Supernova 2008fz
|
We report on the discovery and initial observations of the energetic type IIn supernova (SN), 2008fz. The optical energy emitted by SN 2008fz (based on the light curve over a 88 day period), is possibly the most ever observed for a supernova (1.4 x 10^51 erg). The event was more luminous than the type IIn SN 2006gy, but exhibited same smooth, slowly evolving light curve. As is characteristic of type IIn SN, the early spectra of 2008fz initially exhibited narrow Balmer lines which were replaced by a broader component at later times. The spectra also show a blue continuum with no signs of Ca or Na absorption, suggesting that there is little extinction due to intragalatic dust in the host or circumstellar material. No host galaxy is identified in prior coadded images reaching R ~ 22. From the supernova's redshift, z=0.133, we place an upper limit on the host of M_R=-17. The presence of the SN within such a faint host follows the majority of recently discovered highly luminous SN. A possible reason for this occurrence is the very high star formation rate occurring in low-mass galaxies in combination with the low metallicity environment, which makes the production of very massive stars possible. We determine the peak absolute magnitude of the event to be M_V = -22.3 from the initial photometry and the redshift distance, placing it among the most luminous supernovae discovered.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.HE"
] | 2009-08-13T23:06:51Z |
2205.00024
|
Local density of states and particle entanglement in topological quantum fluids
|
The understanding of particle entanglement is an important goal in the studies of correlated quantum matter. The widely-used method of scanning tunneling spectroscopy -- which measures the local density of states (LDOS) of a many-body system by injecting or removing an electron from it -- is expected to be sensitive to particle entanglement. In this paper, we systematically investigate the relation between the particle entanglement spectrum (PES) and the LDOS of fractional quantum Hall (FQH) states, the paradigmatic strongly-correlated phases of electrons with topological order. Using exact diagonalization, we show that the counting of levels in both the LDOS and PES in the Jain sequence of FQH states can be predicted from the composite fermion theory. We point out the differences between LDOS and PES characterization of the bulk quasihole excitations, and we discuss the conditions under which the LDOS counting can be mapped to that of PES. Our results affirm that tunneling spectroscopy is a sensitive tool for identifying the nature of FQH states.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2022-04-29T18:03:28Z |
astro-ph/0010237
|
Planets and Axisymmetric Mass Loss
|
Bipolar planetary nebulae (PNe), as well as extreme elliptical PNe are formed through the influence of a stellar companion. But half of all PN progenitors are not influenced by any stellar companion, and, as I show here, are expected to rotate very slowly on reaching the upper asymptotic giant branch; hence they expect to form spherical PNe, unless they are spun-up. But since most PNe are not spherical, I argue that about 50 percents of AGB stars are spun-up by planets, even planets having a mass as low as 0.01 times the mass of Jupiter, so they form elliptical PNe. The rotation by itself will not deform the AGB wind, but may trigger another process that will lead to axisymmetric mass loss, e.g., weak magnetic activity, as in the cool magnetic spots model. This model also explains the transition from spherical to axisymmetric mass loss on the upper AGB. For such low mass planets to substantially spin-up the stellar envelope, they should enter the envelope when the star reaches the upper AGB. This "fine-tuning" can be avoided if there are several planets on average around each star, as is the case in the solar system, so that one of them is engulfed when the star reaches the upper AGB.
|
[
"Physics Archive->astro-ph"
] | 2000-10-12T12:17:38Z |
1708.08341
|
Dispersion relations for the time-fractional Cattaneo-Maxwell heat equation
|
In this paper, after a brief review of the general theory of dispersive waves in dissipative media, we present a complete discussion of the dispersion relations for both the ordinary and the time-fractional Cattaneo-Maxwell heat equations. Consequently, we provide a complete characterization of the group and phase velocities for these two cases, together with some non-trivial remarks on the nature of wave dispersion in fractional models.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2017-08-24T20:32:26Z |
2305.15134
|
Networks are Slacking Off: Understanding Generalization Problem in Image Deraining
|
Deep deraining networks consistently encounter substantial generalization issues when deployed in real-world applications, although they are successful in laboratory benchmarks. A prevailing perspective in deep learning encourages using highly complex data for training, with the expectation that richer image background content will facilitate overcoming the generalization problem. However, through comprehensive and systematic experimentation, we discover that this strategy does not enhance the generalization capability of these networks. On the contrary, it exacerbates the tendency of networks to overfit specific degradations. Our experiments reveal that better generalization in a deraining network can be achieved by simplifying the complexity of the training background images. This is because that the networks are ``slacking off'' during training, that is, learning the least complex elements in the image background and degradation to minimize training loss. When the background images are less complex than the rain streaks, the network will prioritize the background reconstruction, thereby suppressing overfitting the rain patterns and leading to improved generalization performance. Our research offers a valuable perspective and methodology for better understanding the generalization problem in low-level vision tasks and displays promising potential for practical application.
|
[
"Computer Science Archive->cs.CV"
] | 2023-05-24T13:27:11Z |
1011.2321
|
Polarised foreground removal at low radio frequencies using rotation measure synthesis: uncovering the signature of hydrogen reionisation
|
Measurement of redshifted 21-cm emission from neutral hydrogen promises to be the most effective method for studying the reionisation history of hydrogen and, indirectly, the first galaxies. These studies will be limited not by raw sensitivity to the signal, but rather, by bright foreground radiation from Galactic and extragalactic radio sources and the Galactic continuum. In addition, leakage due to gain errors and non-ideal feeds conspire to further contaminate low-frequency radio obsevations. This leakage leads to a portion of the complex linear polarisation signal finding its way into Stokes I, and inhibits the detection of the non-polarised cosmological signal from the epoch of reionisation. In this work, we show that rotation measure synthesis can be used to recover the signature of cosmic hydrogen reionisation in the presence of contamination by polarised foregrounds. To achieve this, we apply the rotation measure synthesis technique to the Stokes I component of a synthetic data cube containing Galactic foreground emission, the effect of instrumental polarisation leakage, and redshifted 21-cm emission by neutral hydrogen from the epoch of reionisation. This produces an effective Stokes I Faraday dispersion function for each line of sight, from which instrumental polarisation leakage can be fitted and subtracted. Our results show that it is possible to recover the signature of reionisation in its late stages (z ~ 7) by way of the 21-cm power spectrum, as well as through tomographic imaging of ionised cavities in the intergalactic medium.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.IM"
] | 2010-11-10T09:22:54Z |
2208.13009
|
Object Goal Navigation using Data Regularized Q-Learning
|
Object Goal Navigation requires a robot to find and navigate to an instance of a target object class in a previously unseen environment. Our framework incrementally builds a semantic map of the environment over time, and then repeatedly selects a long-term goal ('where to go') based on the semantic map to locate the target object instance. Long-term goal selection is formulated as a vision-based deep reinforcement learning problem. Specifically, an Encoder Network is trained to extract high-level features from a semantic map and select a long-term goal. In addition, we incorporate data augmentation and Q-function regularization to make the long-term goal selection more effective. We report experimental results using the photo-realistic Gibson benchmark dataset in the AI Habitat 3D simulation environment to demonstrate substantial performance improvement on standard measures in comparison with a state of the art data-driven baseline.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.RO"
] | 2022-08-27T13:26:30Z |
1512.08782
|
Direct-photon+hadron correlations to study parton energy loss with the STAR experiment
|
We report new results of $\gamma_{dir}$+hadron and $\pi^{0}$+hadron azimuthal correlations as a measure of the away-side jet-like correlated yields in central Au+Au and p+p collisions at $\sqrt{s_{NN}}$ = 200 GeV in the STAR experiment from years 2011 and 2009 of data taking, respectively. The charged-hadron per-trigger yields at mid-rapidity $(|\eta| < 1)$ and for transverse momenta $p_{T}^{assoc} > 1.2$ ~GeV/$c$ associated with $\gamma_{dir}$~ and $\pi^{0}$~(for triggers $|\eta| < $0.9, 12 $< p_{T}^{trig} <$ 20 GeV/$c$) in central Au+Au collisions are compared with p+p collisions. The $z_{T}$ ($= \frac{p_{T}^{assoc}}{p_{T}^{trig}}$) dependence, now extending down to $z_{T}$=0.1, of the suppression of the away-side associated yields is presented. We observed that the suppression of away-side associated yields tends to vanish at lower \zT. The dependence of the suppression on both $p_{T}^{assoc}$ and $p_{T}^{trig}$ is also discussed. Finally, these results are compared with various model predictions.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-ex",
"Physics Archive->nucl->nucl-th"
] | 2015-12-29T20:32:57Z |
0705.1559
|
Effects of crosslinks on motor-mediated filament organization
|
Crosslinks and molecular motors play an important role in the organization of cytoskeletal filament networks. Here we incorporate the effect of crosslinks into our model of polar motor-filament organization [Phys. Rev. E {\bf 71}, 050901 (2005)], through suppressing the relative sliding of filaments in the course of motor-mediated alignment. We show that this modification leads to a nontrivial macroscopic behavior, namely the oriented state exhibits a transverse instability in contrast to the isotropic instability that occurs without crosslinks. This transverse instability leads to the formation of dense extended bundles of oriented filaments, similar to recently observed structures in actomyosin. This model also can be applied to situations with two oppositely directed motor species or motors with different processing speeds.
|
[
"Physics Archive->cond-mat->cond-mat.soft"
] | 2007-05-10T22:21:43Z |
2302.10837
|
Performant feature extraction for photometric time series
|
Astronomy is entering the era of large surveys of the variable sky such as Zwicky Transient Facility (ZTF) and the forthcoming Legacy Survey of Space and Time (LSST) which are intended to produce up to a million alerts per night. Such an amount of photometric data requires efficient light-curve pre-processing algorithms for the purposes of subsequent data quality cuts, classification, and characterization analysis. In this work, we present the new library "light-curve" for Python and Rust, which is intended for feature extraction from light curves of variable astronomical sources. The library is suitable for machine learning classification problems: it provides a fast implementation of feature extractors, which outperforms other public available codes, and consists of dozens features describing shape, magnitude distribution, and periodic properties of light curves. It includes not only features which had been shown to provide a high performance in classification tasks, but also new features we developed to improve classification quality of selected types of objects. The "light-curve" library is currently used by the ANTARES, AMPEL, and Fink broker systems for analyzing the ZTF alert stream, and has been selected for use with the LSST.
|
[
"Physics Archive->astro-ph->astro-ph.IM"
] | 2023-02-21T17:39:28Z |
1003.1825
|
Shear Viscosity in the Post-quasistatic Approximation
|
We apply the post-quasi--static approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of anisotropic non-adiabatic radiating and dissipative distributions in General Relativity. Dissipation is described by viscosity and free-streaming radiation, assuming an equation of state to model anisotropy induced by the shear viscosity. We match the interior solution, in non-comoving coordinates, with the Vaidya exterior solution. Two simple models are presented, based on the Schwarzschild and Tolman VI solutions, in the non--adiabatic and adiabatic limit. In both cases the eventual collapse or expansion of the distribution is mainly controlled by the anisotropy induced by the viscosity.
|
[
"Physics Archive->gr-qc"
] | 2010-03-09T08:05:11Z |
1708.09172
|
Finite-temperature behavior of the Bose polaron
|
We consider a mobile impurity immersed in a Bose gas at finite temperature. Using perturbation theory valid for weak coupling between the impurity and the bosons, we derive analytical results for the energy and damping of the impurity for low and high temperatures, as well as for temperatures close to the critical temperature $T_c$ for Bose-Einstein condensation. These results show that the properties of the impurity vary strongly with temperature. In particular, the energy exhibits a non-monotonic behavior close to $T_c$, and the damping rises sharply close to $T_c$. We argue that this behaviour is generic for impurities immersed in an environment undergoing a phase transition that breaks a continuous symmetry. Finally, we discuss how these effects can be detected experimentally.
|
[
"Physics Archive->cond-mat->cond-mat.quant-gas"
] | 2017-08-30T08:50:22Z |
cs/0408008
|
Iterative Quantization Using Codes On Graphs
|
We study codes on graphs combined with an iterative message passing algorithm for quantization. Specifically, we consider the binary erasure quantization (BEQ) problem which is the dual of the binary erasure channel (BEC) coding problem. We show that duals of capacity achieving codes for the BEC yield codes which approach the minimum possible rate for the BEQ. In contrast, low density parity check codes cannot achieve the minimum rate unless their density grows at least logarithmically with block length. Furthermore, we show that duals of efficient iterative decoding algorithms for the BEC yield efficient encoding algorithms for the BEQ. Hence our results suggest that graphical models may yield near optimal codes in source coding as well as in channel coding and that duality plays a key role in such constructions.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2004-08-02T21:52:55Z |
0708.0511
|
Wigner's Dynamical Transition State Theory in Phase Space: Classical and Quantum
|
A quantum version of transition state theory based on a quantum normal form (QNF) expansion about a saddle-centre-...-centre equilibrium point is presented. A general algorithm is provided which allows one to explictly compute QNF to any desired order. This leads to an efficient procedure to compute quantum reaction rates and the associated Gamov-Siegert resonances. In the classical limit the QNF reduces to the classical normal form which leads to the recently developed phase space realisation of Wigner's transition state theory. It is shown that the phase space structures that govern the classical reaction d ynamicsform a skeleton for the quantum scattering and resonance wavefunctions which can also be computed from the QNF. Several examples are worked out explicitly to illustrate the efficiency of the procedure presented.
|
[
"Physics Archive->nlin->nlin.CD"
] | 2007-08-03T13:13:11Z |
astro-ph/0007196
|
A gravitational lens survey with Planck Surveyor
|
The Planck Surveyor cosmic microwave background (CMB) imaging mission will make very sensitive maps of the whole sky at microwave, millimetre (mm) and sub-mm wavelengths. The steep source counts expected in the highest frequency Planck bands are likely to be associated with a strong magnification bias, and so the fraction of galaxies magnified by a factor of two or more could be greater than 10%. In this paper, previous predictions of the significance of the Planck survey for studies of lensing statistics are updated, to reflect our expanded knowledge of the properties of high-redshift dusty galaxies, obtained from far-infrared and sub-mm surveys. A catalogue of probably about 10000 galaxies, but perhaps as many as 100000 or as few as 1000, is expected to be generated from the final Planck all-sky maps. Of order 1000 galaxies, a better determined number, might reasonably be expected to be strongly lensed. Co-ordinated sub-mm and far-infrared follow-up observations made using the SPIRE and PACS instruments aboard the ESA cornerstone mission FIRST - Planck's travelling companion to its L2 orbit - and the ground-based ALMA interferometer array will provide accurate positions and very valuable information about the spectral energy distributions (SEDs), redshifts and astrophysical properties of the galaxies in the Planck catalogue. ALMA and radio images will also reveal their morphology, and the characteristic arc and multiple image structures produced by gravitational lensing. Studies of these bright sub-mm-selected galaxies will allow new insight into the process of galaxy formation and evolution.
|
[
"Physics Archive->astro-ph"
] | 2000-07-14T09:24:29Z |
1805.10768
|
Deep Trustworthy Knowledge Tracing
|
Knowledge tracing (KT), a key component of an intelligent tutoring system, is a machine learning technique that estimates the mastery level of a student based on his/her past performance. The objective of KT is to predict a student's response to the next question. Compared with traditional KT models, deep learning-based KT (DLKT) models show better predictive performance because of the representation power of deep neural networks. Various methods have been proposed to improve the performance of DLKT, but few studies have been conducted on the reliability of DLKT. In this work, we claim that the existing DLKTs are not reliable in real education environments. To substantiate the claim, we show limitations of DLKT from various perspectives such as knowledge state update failure, catastrophic forgetting, and non-interpretability. We then propose a novel regularization to address these problems. The proposed method allows us to achieve trustworthy DLKT. In addition, the proposed model which is trained on scenarios with forgetting can also be easily extended to scenarios without forgetting.
|
[
"Computer Science Archive->cs.AI"
] | 2018-05-28T04:50:24Z |
0810.1954
|
A Variational Study of the Nucleon Wavefunction
|
The structure of the nucleon is studied variationally on the lattice by maximizing the overlap between the nucleon and a trial function generated by an interpolating field containing variational parameters. We examine the effect of the spatial extent of smeared quark sources, the degree of gauge field smearing, the positions of smeared quark sources, inclusion of lower Dirac components and of diquark substructure. Exploratory calculations with quenched Wilson fermions at a pion mass of 900 MeV achieved overlaps as high as 80%, and there was no evidence of diquark substructure.
|
[
"Physics Archive->hep->hep-lat"
] | 2008-10-10T20:09:41Z |
1810.07492
|
Experimentally accessible lower bounds for genuine multipartite entanglement and coherence measures
|
Experimentally quantifying entanglement and coherence are extremely important for quantum resource theory. However, because the quantum state tomography requires exponentially growing measurements with the number of qubits, it is hard to quantify entanglement and coherence based on the full information of the experimentally realized multipartite states. Fortunately, other methods have been found to directly measure the fidelity of experimental states without quantum state tomography. Here we present a fidelity-based method to derive experimentally accessible lower bounds for measures of genuine multipartite entanglement and coherence. On the one hand, the method works for genuine multipartite entanglement measures including the convex-roof extended negativity, the concurrence, the G-concurrence, and the geometric measure for genuine multipartite entanglement. On the other hand, the method also delivers observable lower bounds for the convex roof of the $l_{1}$-norm of coherence, the geometric measure of coherence, and the coherence of formation. Furthermore, all the lower bounds are based on the fidelity between the chosen pure state and the target state, and we obtain the lower bounds of several real experimental states as examples of our results.
|
[
"Physics Archive->quant-ph"
] | 2018-10-17T11:55:38Z |
nucl-ex/0701052
|
Centrality dependence of the $N(\Omega)/N(\phi)$ ratios and $\phi$ $v_{2}$ - a test of thermalization in Au+Au collisions at RHIC
|
We present the centrality dependence of the $N(\Omega)/N(\phi)$ ratios and $\phi$ $v_{2}$ measured in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV by the STAR experiment at RHIC. The results are compared to measurements of other identified particles and recombination model expectations in order to gain insight into the partonic collectivity and possible thermalization of the produced medium.
|
[
"Physics Archive->nucl->nucl-ex"
] | 2007-01-24T12:06:12Z |
1102.0382
|
On the effects of rotation on acoustic stellar pulsations: validity domains of perturbative methods and close frequency pairs
|
Pulsation frequencies of acoustic modes are calculated for realistic rotating stellar models using both a perturbative and a two-dimensional approach. A comparison between the two yields validity domains which are similar to those previously obtained in Reese, Lignieres and Rieutord (2006) for polytropic models. One can also construct validity domains based on polynomial fits to the frequencies from the two-dimensional approach, and these also turn out to be similar, thus further confirming the agreement between the perturbative and two-dimensional approach at low rotation rates. Furthermore, as was previously shown in Espinosa, Perez Hernandez and Roca Cortes (2004), adjacent frequencies in multiplets come close together, thus forming pairs. This phenomena, exclusive to two-dimensional calculations, is shown to be an unlikely explanation of the close frequency pairs observed in delta Scuti stars. A systematic search for all close frequency pairs in the calculated spectrum is also carried out. The number of close frequency pairs is shown to agree with what is expected based on a Poisson distribution, but does not match the number or distribution of close pairs in stars like FG Vir. Furthermore, a lack of close frequency pairs appears at low rotation rates, where frequency multiplets do not overlap. Delta Scuti stars currently reported as having close frequency pairs do not fall in this interval.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2011-02-02T08:49:56Z |
2209.01545
|
OneQ: A Compilation Framework for Photonic One-Way Quantum Computation
|
In this paper, we propose OneQ, the first optimizing compilation framework for one-way quantum computation towards realistic photonic quantum architectures. Unlike previous compilation efforts for solid-state qubit technologies, our innovative framework addresses a unique set of challenges in photonic quantum computing. Specifically, this includes the dynamic generation of qubits over time, the need to perform all computation through measurements instead of relying on 1-qubit and 2-qubit gates, and the fact that photons are instantaneously destroyed after measurements. As pioneers in this field, we demonstrate the vast optimization potential of photonic one-way quantum computing, showcasing the remarkable ability of OneQ to reduce computing resource requirements by orders of magnitude.
|
[
"Physics Archive->quant-ph"
] | 2022-09-04T07:08:56Z |
1802.03850
|
Scientific Methodology: A View from Early String Theory
|
This paper addresses the question as to whether the methodology followed in building and assessing string theory can be considered scientific in the same sense, say, that the methodology followed in building and assessing the Standard Model of particle physics is scientific, by focussing on the "founding" period of the theory. More precisely, its aim is to argue for a positive answer to the above question (there is no real change of scientific status in the way of proceeding and reasoning in fundamental physical research) in the light of a historical analysis of the early developments of the string theoretical framework.
|
[
"Physics Archive->physics->physics.hist-ph"
] | 2018-02-12T00:37:53Z |
1210.5483
|
New Features in AST - a WCS Management and Manipulation Library
|
Recent developments in the AST library are described, including a Python interface, support for the FITS-WCS "-TAB" system for storing tabular co-ordinate information, and extended support for representing distortions in spatial projections, using several schemes in common use (IRAF TNX/ZPX, Spitzer SIP, NOAO TPV and SCAMP).
|
[
"Physics Archive->astro-ph->astro-ph.IM"
] | 2012-10-19T17:43:25Z |
1703.07363
|
The Arrow of Time in the collapse of collisionless self-gravitating systems: non-validity of the Vlasov-Poisson equation during violent relaxation
|
The collapse of a collisionless self-gravitating system, with the fast achievement of a quasi-stationary state, is driven by violent relaxation, with a typical particle interacting with the time-changing collective potential. It is traditionally assumed that this evolution is governed by the Vlasov-Poisson equation, in which case entropy must be conserved. We run N-body simulations of isolated self-gravitating systems, using three simulation codes: NBODY-6 (direct summation without softening), NBODY-2 (direct summation with softening) and GADGET-2 (tree code with softening), for different numbers of particles and initial conditions. At each snapshot, we estimate the Shannon entropy of the distribution function with three different techniques: Kernel, Nearest Neighbor and EnBiD. For all simulation codes and estimators, the entropy evolution converges to the same limit as N increases. During violent relaxation, the entropy has a fast increase followed by damping oscillations, indicating that violent relaxation must be described by a kinetic equation other than the Vlasov-Poisson, even for N as large as that of astronomical structures. This indicates that violent relaxation cannot be described by a time-reversible equation, shedding some light on the so-called "fundamental paradox of stellar dynamics". The long-term evolution is well described by the orbit-averaged Fokker-Planck model, with Coulomb logarithm values in the expected range 10-12. By means of NBODY-2, we also study the dependence of the 2-body relaxation time-scale on the softening length. The approach presented in the current work can potentially provide a general method for testing any kinetic equation intended to describe the macroscopic evolution of N-body systems.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2017-03-21T18:00:09Z |
cond-mat/0208154
|
Comment on ``Experimental Demonstration of Violations of the Second Law of Thermodynamicsfor Small Systems and Short Time Scales''
|
The experimental verification of the fluctuation theorem by Wang et al. is explained in terms of a simple Langevin dynamics. This implies that the entropy consuming trajectories found by Wang et al. are fluctuations generated by a random force and do not violate the second law.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2002-08-08T06:11:32Z |
1405.2759
|
Multiple Coulomb Scattering in Thin Silicon
|
We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 um) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->physics->physics.ins-det"
] | 2014-05-12T13:53:55Z |
1212.2546
|
A Learning Framework for Morphological Operators using Counter-Harmonic Mean
|
We present a novel framework for learning morphological operators using counter-harmonic mean. It combines concepts from morphology and convolutional neural networks. A thorough experimental validation analyzes basic morphological operators dilation and erosion, opening and closing, as well as the much more complex top-hat transform, for which we report a real-world application from the steel industry. Using online learning and stochastic gradient descent, our system learns both the structuring element and the composition of operators. It scales well to large datasets and online settings.
|
[
"Computer Science Archive->cs.CV"
] | 2012-12-11T17:29:04Z |
1904.01730
|
Sequencing and Scheduling for Multi-User Machine-Type Communication
|
In this paper, we propose joint sequencing and scheduling optimization for uplink machine-type communication (MTC). We consider multiple energy-constrained MTC devices that transmit data to a base station following the time division multiple access (TDMA) protocol. Conventionally, the energy efficiency performance in TDMA is optimized through multi-user scheduling, i.e., changing the transmission block length allocated to different devices. In such a system, the sequence of devices for transmission, i.e., who transmits first and who transmits second, etc., has not been considered as it does not have any impact on the energy efficiency. In this work, we consider that data compression is performed before transmission and show that the multi-user sequencing is indeed important. We apply three popular energy-minimization system objectives, which differ in terms of the overall system performance and fairness among the devices. We jointly optimize both multi-user sequencing and scheduling along with the compression and transmission rate control. Our results show that multi-user sequence optimization significantly improves the energy efficiency performance of the system. Notably, it makes the TDMA-based multi-user transmissions more likely to be feasible in the lower latency regime, and the performance gain is larger when the delay bound is stringent.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2019-04-03T01:17:03Z |
quant-ph/0407049
|
Aspects of generic entanglement
|
We study entanglement and other correlation properties of random states in high-dimensional bipartite systems. These correlations are quantified by parameters that are subject to the "concentration of measure" phenomenon, meaning that on a large-probability set these parameters are close to their expectation. For the entropy of entanglement, this has the counterintuitive consequence that there exist large subspaces in which all pure states are close to maximally entangled. This, in turn, implies the existence of mixed states with entanglement of formation near that of a maximally entangled state, but with negligible quantum mutual information and, therefore, negligible distillable entanglement, secret key, and common randomness. It also implies a very strong locking effect for the entanglement of formation: its value can jump from maximal to near zero by tracing over a number of qubits negligible compared to the size of total system. Furthermore, such properties are generic. Similar phenomena are observed for random multiparty states, leading us to speculate on the possibility that the theory of entanglement is much simplified when restricted to asymptotically generic states. Further consequences of our results include a complete derandomization of the protocol for universal superdense coding of quantum states.
|
[
"Physics Archive->quant-ph"
] | 2004-07-07T19:55:33Z |
0704.3399
|
Cooperative Transmission Protocols with High Spectral Efficiency and High Diversity Order Using Multiuser Detection and Network Coding
|
Cooperative transmission is an emerging communication technique that takes advantages of the broadcast nature of wireless channels. However, due to low spectral efficiency and the requirement of orthogonal channels, its potential for use in future wireless networks is limited. In this paper, by making use of multiuser detection (MUD) and network coding, cooperative transmission protocols with high spectral efficiency, diversity order, and coding gain are developed. Compared with the traditional cooperative transmission protocols with single-user detection, in which the diversity gain is only for one source user, the proposed MUD cooperative transmission protocols have the merits that the improvement of one user's link can also benefit the other users. In addition, using MUD at the relay provides an environment in which network coding can be employed. The coding gain and high diversity order can be obtained by fully utilizing the link between the relay and the destination. From the analysis and simulation results, it is seen that the proposed protocols achieve higher diversity gain, better asymptotic efficiency, and lower bit error rate, compared to traditional MUD and to existing cooperative transmission protocols.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2007-04-25T15:58:10Z |
1905.06337
|
How Do Galaxies trace a large scale structure?: A case study around a massive protocluster at $z=3.13$
|
In the hierarchical theory of galaxy formation, a galaxy overdensity is a hallmark of a massive cosmic structure. However, it is less well understood how different types of galaxies trace the underlying large-scale structure. Motivated by the discovery of a z=3.13 protocluster, we examine how the same structure is populated by Ly$\alpha$-emitting galaxies (LAEs). To this end, we have undertaken a deep narrow-band imaging survey sampling Ly$\alpha$ emission at this redshift. Of the 93 LAE candidates within a 36'x36'~(70x70~Mpc^2) field, 21 galaxies form a significant surface overdensity (delta_g=3.3+/-0.9), which is spatially segregated from the Lyman break galaxy (LBG) overdensity. One possible interpretation is that they trace two separate structures of comparable masses (~ 10^{15}M_sun) where the latter is hosted by a halo assembled at an earlier time. We speculate that the dearth of LAEs in the LBG overdensity region may signal the role of halo assembly bias in galaxy formation, which would suggest that different search techniques may be biased accordingly to the formation age or dynamical state of the host halo. The median Ly$\alpha$- and UV luminosity is 30--70\% higher for the protocluster LAEs relative to the field. This difference cannot be explained by the galaxy overdensity alone, and may require a top-heavy mass function, higher star formation efficiency for protocluster halos, or suppression of galaxy formation in low-mass halos. A luminous Ly$\alpha$ blob and an ultramassive galaxy found in this region paint a picture consistent with the expected early growth of galaxies in clusters.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | 2019-05-15T19:50:30Z |
1905.10655
|
A Light Curve Analysis of 32 Recent Galactic Novae --- Distances and White Dwarf Masses
|
We obtained the absolute magnitudes, distances, and white dwarf (WD) masses of 32 recent galactic novae based on the time-stretching method for nova light curves. A large part of the light/color curves of two classical novae often overlap each other if we properly squeeze/stretch their timescales. Then, a target nova brightness is related to the other template nova brightness by $(M_V[t])_{\rm template} = (M_V[t/f_{\rm s}] - 2.5 \log f_{\rm s})_{\rm target}$, where $t$ is the time, $M_V[t]$ is the absolute $V$ magnitude, and $f_{\rm s}$ is their timescaling ratio. Moreover, when these two time-stretched light curves, $(t/f_{\rm s})$-$(M_V-2.5 \log f_{\rm s})$, overlap each other, $(t/f_{\rm s})$-$(B-V)_0$ do too, where $(B-V)_0$ is the intrinsic $B-V$ color. Thus, the two nova tracks overlap each other in the $(B-V)_0$-$(M_V-2.5 \log f_{\rm s})$ diagram. Inversely using these properties, we obtain/confirm the distance and reddening by comparing each nova light/color curves with the well calibrated template novae. We classify the 32 novae into two types, LV Vul and V1500 Cyg types, in the time-stretched $(B-V)_0$-$(M_V-2.5 \log f_{\rm s})$ color-magnitude diagram. The WD mass is obtained by direct comparison of the model $V$ light curves with the observation. Thus, we obtain a uniform set of 32 galactic classical novae that provides the distances and WD masses from a single method. Many novae broadly follow the universal decline law and the present method can be applied to them, while some novae largely deviate from the universal decline law and so the method cannot be directly applied to them. We discuss such examples.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2019-05-25T19:00:39Z |
math/0311180
|
Vanishing cycles, the generalized Hodge Conjecture and Gr\"obner bases
|
Let $X$ be a general complete intersection of a given multi-degree in a complex projective space. Suppose that the anti-canonical line bundle of $X$ is ample. Using the cylinder homomorphism associated with the family of complete intersections contained in $X$, we prove that the vanishing cycles in the middle homology group of $X$ are represented by topological cycles whose support is contained in a proper Zariski closed subset $T\subset X$ of certain codimension. In some cases, we can find such a Zariski closed subset $T$ with codimension equal to the upper bound obtained from the Hodge structure of the middle cohomology group of $X$ by means of Gr\"obner bases. Hence a consequence of the generalized Hodge conjecture is verified in these cases.
|
[
"Mathematics Archive->math.AG"
] | 2003-11-12T05:40:25Z |
1704.03328
|
Zero-dimensional limit of the two-dimensional Lugiato-Lefever equation
|
We study effects of tight harmonic-oscillator confinement on the electromagnetic field in a laser cavity by solving the two-dimensional Lugiato-Lefever (2D LL) equation, taking into account self- focusing or defocusing nonlinearity, losses, pump, and the trapping potential. Tightly confined (quasi-zero-dimensional) optical modes (pixels), produced by this model, are analyzed by means of the variational approximation, which provides a qualitative picture of the ensuing phenomena. This is followed by systematic simulations of the time-dependent 2D LL equation, which reveal the shape, stability, and dynamical behavior of the resulting localized patterns. In this way, we produce stability diagrams for the expected pixels. Then, we consider the LL model with the vortical pump, showing that it can produce stable pixels with embedded vorticity (vortex solitons) in remarkably broad sta- bility areas. Alongside confined vortices with the simple single-ring structure, in the latter case the LL model gives rise to stable multi-ring states, with a spiral phase field. In addition to the numeri- cal results, a qualitatively correct description of the vortex solitons is provided by the Thomas-Fermi approximation.
|
[
"Physics Archive->nlin->nlin.PS",
"Physics Archive->physics->physics.optics"
] | 2017-04-11T14:49:02Z |
hep-ph/9502286
|
Short and Long Distance Interplay in Inclusive $ B \to X_d \gamma $ Decays
|
We analyze the short and long distance contributions to inclusive $B \rightarrow X_d \gamma$ decay, paying particular attention to the dependence on the Cabibbo-Kobayashi-Maskawa parameter $V_{td}$. We discuss penguin diagrams with internal $u$ and $c$ quarks in the framework of the effective field theory. We also estimate the size of possible long range contributions by using vector meson dominance.
|
[
"Physics Archive->hep->hep-ph"
] | 1995-02-13T16:24:48Z |
0706.0203
|
Universal quantum computation in decoherence-free subspaces with hot trapped-ions
|
We consider interactions that generate a universal set of quantum gates on logical qubits encoded in a collective-dephasing-free subspace, and discuss their implementations with trapped ions. This allows for the removal of the by-far largest source of decoherence in current trapped-ion experiments, collective dephasing. In addition, an explicit parametrization of all two-body Hamiltonians able to generate such gates without the system's state ever exiting the protected subspace is provided.
|
[
"Physics Archive->quant-ph"
] | 2007-06-01T19:32:16Z |
1709.09551
|
What you lose when you snooze: how duty cycling impacts on the contact process in opportunistic networks
|
In opportunistic networks, putting devices in energy saving mode is crucial to preserve their battery, and hence to increase the lifetime of the network and foster user participation. A popular strategy for energy saving is duty cycling. However, when in energy saving mode, users cannot communicate with each other. The side effects of duty cycling are twofold. On the one hand, duty cycling may reduce the number of usable contacts for delivering messages, increasing intercontact times and delays. On the other hand, duty cycling may break long contacts into smaller contacts, thus also reducing the capacity of the opportunistic network. Despite the potential serious effects, the role played by duty cycling in opportunistic networks has been often neglected in the literature. In order to fill this gap, in this paper we propose a general model for deriving the pairwise contact and intercontact times measured when a duty cycling policy is superimposed on the original encounter process determined only by node mobility. The model we propose is general, i.e., not bound to a specific distribution of contact and intercontact times, and very accurate, as we show exploiting two traces of real human mobility for validation. Using this model, we derive several interesting results about the properties of measured contact and intercontact times with duty cycling: their distribution, how their coefficient of variation changes depending on the duty cycle value, how the duty cycling affects the capacity and delay of an opportunistic network. The applicability of these results is broad, ranging from performance models for opportunistic networks that factor in the duty cycling effect, to the optimisation of the duty cycle to meet a certain target performance.
|
[
"Computer Science Archive->cs.NI"
] | 2017-09-27T14:23:58Z |
hep-th/9809155
|
Vacuum Radiation in Conformally Invariant Quantum Field Theory
|
Although the whole conformal group $SO(4,2)$ can be considered as a symmetry in a classical massless field theory, the subgroup of special conformal transformations (SCT), usually related to transitions to uniformly accelerated frames, causes vacuum radiation in the corresponding quantum field theory, in analogy to the Fulling-Unruh effect. The spectrum of the outgoing particles can be calculated exactly and proves to be a generalization of the Planckian one.
|
[
"Physics Archive->hep->hep-th"
] | 1998-09-21T16:08:05Z |
2205.07842
|
A globalisation of Jones and Alexander polynomials constructed from a graded intersection of two Lagrangians in a configuration space
|
We consider two Laurent polynomials in two variables associated to a braid, given by {\em graded intersections} between {\em fixed Lagrangians in configuration spaces}. In order to get link invariants, we notice that we have to quotient by a quadratic relation. Then we prove by topological tools that this relation is sufficient and the first graded intersection gives an invariant which is the Jones polynomial. This shows a {\em topological model for the Jones polynomial} and a direct {\em topological proof}\hspace{0.4mm} that it is a well-defined invariant. The other intersection model in the quotient turns out to be an invariant globalising the Jones and Alexander polynomials. This globalisation in the quotient ring is given by a {\em specific interpolation between the Alexander and Jones polynomials}.
|
[
"Mathematics Archive->math.AT",
"Mathematics Archive->math.GT"
] | 2022-05-16T17:52:22Z |
0804.0746
|
Orbital stability of the black soliton to the Gross-Pitaevskii equation
|
We establish the orbital stability of the black soliton, or kink solution, $\v_0(x) = \th \big(\frac{x}{\sqrt{2}} \big)$, to the one-dimensional Gross-Pitaevskii equation, with respect to perturbations in the energy space.
|
[
"Mathematics Archive->math.AP"
] | 2008-04-04T14:24:00Z |
cond-mat/0508604
|
Breaking of ergodicity and long relaxation times in systems with long-range interactions
|
The thermodynamic and dynamical properties of an Ising model with both short range and long range, mean field like, interactions are studied within the microcanonical ensemble. It is found that the relaxation time of thermodynamically unstable states diverges logarithmically with system size. This is in contrast with the case of short range interactions where this time is finite. Moreover, at sufficiently low energies, gaps in the magnetization interval may develop to which no microscopic configuration corresponds. As a result, in local microcanonical dynamics the system cannot move across the gap, leading to breaking of ergodicity even in finite systems. These are general features of systems with long range interactions and are expected to be valid even when the interaction is slowly decaying with distance.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | 2005-08-25T14:38:28Z |
2209.03530
|
Gluing non-unique Navier-Stokes solutions
|
We construct non-unique Leray solutions of the forced Navier-Stokes equations in bounded domains via gluing methods. This demonstrates a certain locality and robustness of the non-uniqueness discovered by the authors in [1].
|
[
"Mathematics Archive->math.AP"
] | 2022-09-08T02:12:12Z |
1604.00064
|
Temperature-dependent optical properties of gold thin films
|
Understanding the temperature dependence of the optical properties of thin metal films is critical for designing practical devices for high temperature applications in a variety of research areas, including plasmonics and near-field radiative heat transfer. Even though the optical properties of bulk metals at elevated temperatures have been studied, the temperature-dependent data for thin metal films, with thicknesses ranging from few tens to few hundreds of nanometers, is largely missing. In this work we report on the optical constants of single- and polycrystalline gold thin films at elevated temperatures in the wavelength range from 370 to 2000 nm. Our results show that while the real part of the dielectric function changes marginally with increasing temperature, the imaginary part changes drastically. For 200-nm-thick single- and polycrystalline gold films the imaginary part of the dielectric function at 500 0C becomes nearly twice larger than that at room temperature. In contrast, in thinner films (50-nm and 30-nm) the imaginary part can show either increasing or decreasing behavior within the same temperature range and eventually at 500 0C it becomes nearly 3-4 times larger than that at room temperature. The increase in the imaginary part at elevated temperatures significantly reduces the surface plasmon polariton propagation length and the quality factor of the localized surface plasmon resonance for a spherical particle. We provide experiment-fitted models to describe the temperature-dependent gold dielectric function as a sum of one Drude and two Critical Point oscillators. These causal analytical models could enable accurate multiphysics modelling of gold-based nanophotonic and plasmonic elements in both frequency and time domains.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2016-03-31T21:49:07Z |
hep-ph/9708400
|
Dynamically Broken Scale Invariance and Cosmology
|
A new scalar-tensor theory of gravity induced by dynamically broken scale invariance is proposed, and its cosmological implications are discussed. It is found that the model admits an inflation via the Hawking-Moss bubbling, but the inflation rate remains undetermined due to the strong gravity limit. In light of this, scale-invariant metric perturbations having a dominant tensor component can be generated without slow-rollover. In addition, the deviation from the standard hot big-bang is vanishingly small after inflation.
|
[
"Physics Archive->astro-ph",
"Physics Archive->hep->hep-ph"
] | 1997-08-20T04:13:29Z |
cond-mat/0608195
|
Ferroelectricity in perovskite $HoMnO_3$ and $YMnO_3$
|
Ferroelectricity is observed in orthorhombic $HoMnO_3$ and $YMnO_3$ at the magnetic lock-in transitions into an E-type structure or an incommensurate phase with a temperature independent wave vector, respectively. In $HoMnO_3$ the ferroelectric polarization strongly depends on the external magnetic field indicating the involvement of the rare earth moment order in this compound. The results are discussed within the framework of recent theoretical models, in particular the double exchange driven polar displacements predicted for E-type magnetic structures.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2006-08-08T13:40:43Z |
1704.00975
|
Excitonic effects in the optical properties of 2D materials: An equation of motion approach
|
We present a unified description of the excitonic properties of four monolayer transition-metal dichalcogenides (TMDC's) using an equation of motion method for deriving the Bethe-Salpeter equation in momentum space. Our method is able to cope with both continuous and tight-binding Hamiltonians, and is less computational demanding than the traditional first-principles approach. We show that the role of the exchange energy is essential to obtain a good description of the binding energy of the excitons. The exchange energy at the $\Gamma-$point is also essential to obtain the correct position of the C-exciton peak. Using our model we obtain a good agreement between the Rydberg series measured for WS$_2$. We discuss how the absorption and the Rydberg series depend on the doping. Choosing $r_0$ and the doping we obtain a good qualitative agreement between the experimental absorption and our calculations for WS$_2$. We also derive a semi-analytical version of Ellitot's formula for TMDC's.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall"
] | 2017-04-04T12:20:25Z |
2303.03644
|
Quantifying separability in limit groups via representations
|
We show that for any finitely generated subgroup $H$ of a limit group $L$ there exists a finite-index subgroup $K$ containing $H$, such that $K$ is a subgroup of a group obtained from $H$ by a series of extensions of centralizers and free products with $\mathbb Z$. If $H$ is non-abelian, the $K$ is fully residually $H$. We also show that for any finitely generated subgroup of a limit group, there is a finite-dimensional representation of the limit group which separates the subgroup in the induced Zariski topology. As a corollary, we establish a polynomial upper bound on the size of the quotients used to separate a finitely generated subgroup in a limit group. This generalizes the results of Louder, McReynolds and Patel. Another corollary is that a hyperbolic limit group satisfies the Geometric Hanna Neumann conjecture.
|
[
"Mathematics Archive->math.GR"
] | 2023-03-07T04:21:51Z |
1901.08795
|
Giant Enhancement of Third Harmonic Generation from Ge2Sb2Te5 based Fabry-Perot Cavity
|
Third-order harmonic generation (THG) plays a vital role in microscopy, optical communications etc. Conventional methods of obtaining efficient THG in macroscopic crystal is already mature; however, they will finally limit the miniaturization and integration of on-chip laser sources. To date, THG from either photonic crystals or metamaterials provide compact photonic platforms, however selection of materials remains elusive. Herein, we experimentally demonstrate a giant enhancement of THG efficiency from an air/high index Ge2Sb2Te5 (GST225) /gold multi-layered Fabry-Perot cavity. At cavity resonant wavelength in near-infrared regime, the efficiency of THG from a 50 nm thick amorphous GST225 planar film is boosted by 422 times compared to that of nonresonant conditions. Interestingly, the THG efficiency has a dramatic decrease of three orders when the structural state of GST225 is transformed from amorphous to crystalline. Our findings have a potential for achieving ultra-compact nonlinear optical source with high efficiency and switchable functionality.
|
[
"Physics Archive->physics->physics.optics"
] | 2019-01-25T09:30:44Z |
2312.02689
|
Limit theorems for Birkhoff sums and local times of the periodic Lorentz gas with infinite horizon
|
This work is a contribution to the study of the ergodic and stochastic properties of Z^d-periodic dynamical systems preserving an infinite measure. We establish functional limit theorems for natural Birkhoff sums related to local times of the Z^d-periodic Lorentz gas with infinite horizon, for both the collision map and the flow. In particular, our results apply to the difference between the numbers of collisions in two different cells. Because of the Z^d-periodicity of the model we are interested in, these Birkhoff sums can be rewritten as additive functionals of a Birkhoff sum of the Sinai billiard. For completness and in view of future studies, we state a general result of convergence of additive functionals of Birkhoff sums of chaotic probability preserving dynamical systems under general assumptions.
|
[
"Mathematics Archive->math.DS"
] | 2023-12-05T11:45:49Z |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.