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cond-mat/0110587
|
Cooperative Jahn-Teller transition and resonant x-ray scattering in thin film ${\rm LaMnO_3}$
|
Epitaxial thin films of stoichiometric ${\rm LaMnO_3}$ were grown on ${\rm SrTiO_3(110)}$ substrates using the pulsed laser deposition technique. From the high resolution x-ray diffraction measurements, the lattice parameters were determined as a function of temperature and the cooperative Jahn-Teller transition was found to occur at $T_{JT}$=573.0 K. Also measured was resonant x-ray scattering intensity of the orthorhombic (100) peak of ${\rm LaMnO_3}$ near the Mn K edge from low temperatures to above $T_{JT}$. We demonstrate that the integrated intensity of the (100) peak is proportional to the 3/2 power of the orthorhombic strain at all temperatures, and thus provide an experimental evidence that the resonant scattering near the Mn K edge in ${\rm LaMnO_3}$ is largely due to the Jahn-Teller effect.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2001-10-29T10:58:57Z |
2202.09408
|
Unsupervised strategies for identifying optimal parameters in Quantum Approximate Optimization Algorithm
|
As combinatorial optimization is one of the main quantum computing applications, many methods based on parameterized quantum circuits are being developed. In general, a set of parameters are being tweaked to optimize a cost function out of the quantum circuit output. One of these algorithms, the Quantum Approximate Optimization Algorithm stands out as a promising approach to tackling combinatorial problems. However, finding the appropriate parameters is a difficult task. Although QAOA exhibits concentration properties, they can depend on instances characteristics that may not be easy to identify, but may nonetheless offer useful information to find good parameters. In this work, we study unsupervised Machine Learning approaches for setting these parameters without optimization. We perform clustering with the angle values but also instances encodings (using instance features or the output of a variational graph autoencoder), and compare different approaches. These angle-finding strategies can be used to reduce calls to quantum circuits when leveraging QAOA as a subroutine. We showcase them within Recursive-QAOA up to depth $3$ where the number of QAOA parameters used per iteration is limited to $3$, achieving a median approximation ratio of $0.94$ for MaxCut over $200$ Erd\H{o}s-R\'{e}nyi graphs. We obtain similar performances to the case where we extensively optimize the angles, hence saving numerous circuit calls.
|
[
"Physics Archive->quant-ph"
] | 2022-02-18T19:55:42Z |
cond-mat/9803335
|
Shot noise in diffusive conductors: A quantitative analysis of electron-phonon interaction effects
|
Using the 'drift-diffusion-Langevin' equation, we have quantitatively analyzed the effects of electron energy relaxation via their interaction with phonons, generally in presence of electron-electron interaction, on shot noise in diffusive conductors. We have found that the noise power $ S_I(\omega )$ (both at low and high observation frequencies $\omega $) drops to half of its 'mesoscopic' value only at $\beta \gtrsim 100,$ where $\beta $ is the ratio of the sample length $L$ to the energy relaxation length $l_{% {\rm ph}}$ (the latter may be much larger then the dephasing length). It means in particular that at low temperatures the shot noise may be substantial even when $L\sim 10^{-2}$ -- $10^{-1}$ cm, and the conductor is 'macroscopic' in any other respect.
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 1998-03-27T05:31:29Z |
math/9810117
|
Relative Bott-Chern Secondary Characteristic Classes
|
In this paper, we introduce six axioms for relative Bott-Chern secondary characteristic classes and prove the uniqueness and existence theorem for them. Such a work provides us a natural way to understand and hence to prove the arithmetic Grothendieck-Riemann-Roch theorem.
|
[
"Mathematics Archive->math.AG",
"Mathematics Archive->math.DG"
] | 1998-10-19T02:07:12Z |
2112.15193
|
Materials under high pressure: A chemical perspective
|
At high pressure, the typical behavior of elements dictated by the periodic table - including oxidation numbers, stoichiometries in compounds, and reactivity, to name but a few - is altered dramatically. As pressure is applied, the energetic ordering of atomic orbitals shifts, allowing core orbitals to become chemically active, atypical electron configurations to occur, and in some cases, non-atom-centered orbitals to form in the interstices of solid structures. Strange stoichiometries, structures, and bonding motifs result. Crystal structure prediction tools, not burdened by preconceived notions about structural chemistry learned at atmospheric pressure, have been applied to great success to explore phase diagrams at high pressure, identifying novel structures in diverse chemical systems. Several of these have been subsequently observed by experimental investigations, whose access to high-pressure regimes is bolstered by advances in diamond anvil cell and dynamic compression techniques. The joint efforts of experiment and theory have led to particular success in the realm of high-temperature superconductors, identifying many novel phases whose superconducting transition approaches room temperature.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2021-12-30T19:57:14Z |
2003.12901
|
liOS: Lifting iOS apps for fun and profit
|
Although iOS is the second most popular mobile operating system and is often considered the more secure one, approaches to automatically analyze iOS applications are scarce and generic app analysis frameworks do not exist. This is on the one hand due to the closed ecosystem putting obstacles in the way of reverse engineers and on the other hand due to the complexity of reverse engineering and analyzing app binaries. Reliably lifting accurate call graphs, control flows, and data dependence graphs from binary code, as well as reconstructing object-oriented high-level concepts is a non-trivial task and the choice of the lifted target representation determines the analysis capabilities. None of the various existing intermediate representations is a perfect fit for all types of analysis, while the detection of vulnerabilities requires techniques ranging from simple pattern matching to complex inter-procedural data flow analyses. We address this gap by introducing liOS, a binary lifting and analysis framework for iOS applications that extracts lifted information from several frontends and unifies them in a "supergraph" representation that tolerates missing parts and is further extended and interlinked by liOS "passes". A static analysis of the binary is then realized in the form of graph traversal queries, which can be considered as an advancement of classic program query languages. We illustrate this approach by means of a typical JavaScript/Objective-C bridge, which can lead to remote code execution in iOS applications.
|
[
"Computer Science Archive->cs.CR"
] | 2020-03-28T22:30:12Z |
2007.15647
|
Fast Thresholded SC-Flip Decoding of Polar Codes
|
SC-Flip (SCF) decoding algorithm shares the attention with the common polar code decoding approaches due to its low-complexity and improved error-correction performance. However, the inefficient criterion for locating the correct bit-flipping position in SCF decoding limits its improvements. Due to its improved bit-flipping criterion, Thresholded SCF (TSCF) decoding algorithm exhibits a superior error-correction performance and lower computational complexity than SCF decoding. However, the parameters of TSCF decoding depend on multiple channel and code parameters, and are obtained via Monte-Carlo simulations. Our main goal is to realize TSCF decoding as a practical polar decoder implementation. To this end, we first realize an approximated threshold value that is independent of the code parameters and precomputations. The proposed approximation has negligible error-correction performance degradation on the TSCF decoding. Then, we validate an alternative approach for forming a critical set that does not require precomputations, which also paves the way to the implementation of the Fast-TSCF decoder. Compared to the existing fast SCF implementations, the proposed Fast-TSCF decoder has $0.24$ to $0.41$ dB performance gain at frame error rate of $10^{-3}$, without any extra cost. Compared to the TSCF decoding, Fast-TSCF does not depend on precomputations and requires $87\%$ fewer decoding steps. Finally, implementation results in TSMC 65nm CMOS technology show that the Fast-TSCF decoder is $20\%$ and $82\%$ more area-efficient than the state-of-the-art fast SCF and fast SC-List decoder architectures, respectively.
|
[
"Computer Science Archive->cs.AR"
] | 2020-07-30T17:58:41Z |
0710.4306
|
Unifying dark components and crossing the phantom divide with a classical Dirac field
|
In this paper we consider a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model whit cosmological constant, containing a stiff fluid and a classical Dirac field. The proposed cosmological scenario describes the evolution of effective dark matter and dark energy components reproducing, with the help of that effective multifluid configuration, the quintessential behavior. We find the value of the scale factor where the effective dark energy component crosses the phantom divide. The model we introduce, which can be considered as a modified $\La$CDM one, is characterized by a set of parameters which may be constrained by the astrophysical observations available up to date.
|
[
"Physics Archive->astro-ph"
] | 2007-10-23T18:06:48Z |
1802.03336
|
The Monadic Second Order Theory of Grid-Free 1-Safe Petri Nets is Decidable
|
Finite 1-safe Petri nets, also called \emph{net systems}, are natural models of asynchronous concurrency. The event structure of a net system describes all its possible executions and their concurrent nature: two events may be causally ordered, occur in parallel or be conflicting. Monadic second order logic (MSO) can be used to specify behavioural properties of net systems. Thiagarajan's conjecture states that MSO is decidable if and only if the net system is grid-free. The present paper gives a positive answer to this conjecture.
|
[
"Computer Science Archive->cs.LO"
] | 2018-02-09T16:38:46Z |
0808.0653
|
On the formal grade of finitely generated modules over local rings
|
Let \fa be an ideal of a local ring (R,\fm) and M a finitely generated R-module. This paper concerns the notion \fgrade(\fa,M), the formal grade of M with respect to \fa (i.e. the least integer i such that {\vpl}_nH^i_{\fm}(M/\fa^n M)\neq 0). We show that \fgrade(\fa,M)\geq \depth M-\cd_{\fa}(M), and as a result, we establish a new characterization of Cohen-Macaulay modules. As an application of this characterization, we show that if M is Cohen-Macaulay and L a pure submodule of M with the same support as M, then \fgrade(\fa,L)=\fgrade(\fa,M). Also, we give a generalization of the Hochster-Eagon result on Cohen-Macaulayness of invariant rings.
|
[
"Mathematics Archive->math.AC"
] | 2008-08-05T13:57:50Z |
1710.06842
|
Measuring the unmeasurable - a project of domestic violence risk prediction and management
|
The prevention of domestic violence (DV) have aroused serious concerns in Taiwan because of the disparity between the increasing amount of reported DV cases that doubled over the past decade and the scarcity of social workers. Additionally, a large amount of data was collected when social workers use the predominant case management approach to document case reports information. However, these data were not properly stored or organized. To improve the efficiency of DV prevention and risk management, we worked with Taipei City Government and utilized the 2015 data from its DV database to perform a spatial pattern analysis of the reports of DV cases to build a DV risk map. However, during our map building process, the issue of confounding bias arose because we were not able to verify if reported cases truly reflected real violence occurrence or were simply false reports from potential victim's neighbors. Therefore, we used the random forest method to build a repeat victimization risk prediction model. The accuracy and F1-measure of our model were 96.3% and 62.8%. This model helped social workers differentiate the risk level of new cases, which further reduced their major workload significantly. To our knowledge, this is the first project that utilized machine learning in DV prevention. The research approach and results of this project not only can improve DV prevention process, but also be applied to other social work or criminal prevention areas.
|
[
"Computer Science Archive->cs.CY"
] | 2017-10-18T17:48:51Z |
math/0012131
|
Invitation to higher local fields (Introduction)
|
The monograph "Invitation to higher local fields" is the result of the conference on higher local fields held in Muenster, August 29 to September 5, 1999. The aim is to provide an introduction to higher local fields (more generally complete discrete valuation fields with arbitrary residue field) and render the main ideas of this theory (Part I), as well as to discuss several applications and connections to other areas (Part II). The volume grew as an extended version of talks given at the conference. The two parts are separated by a paper of K. Kato, an IHES preprint from 1980 which has never been published. We hope that the volume will be a useful introduction and guide to the subject. The contributions to this volume were received over the period November 1999 to August 2000 and the electronic publication date is 10 December 2000. This is the introduction: math.NT/0012131. Other arXiv references are as follows: Part I: Sections 1: math.NT/0012132, 2: math.NT/0012133, A: math.NT/0012134, 4: math.NT/0012135, 5: math.NT/0012136, 6: math.NT/0012137, 7: math.NT/0012138, 8: math.NT/0012139, 9: math.NT/0012140, 10: math.NT/0012141, 11: math.NT/0012142, 12: math.NT/0012143, 13: math.NT/0012144, 14: math.NT/0012145, 15: math.NT/0012146, 16: math.NT/0012147, 17: math.NT/0012148, 18: math.NT/0012149 . Interlude: math.NT/0012150 . Part II: Sections 1: math.NT/0012151, 2: math.NT/0012152, 3: math.NT/0012153, 4: math.NT/0012154, 5: math.NT/0012155, 6: math.NT/0012156, 7: math.NT/0012157, 8: math.NT/0012158, 9: math.NT/0012159, 10: math.NT/0012160 .
|
[
"Mathematics Archive->math.AG",
"Mathematics Archive->math.NT"
] | 2000-12-18T03:45:56Z |
2007.00984
|
Internal modes of oscillations of topological solitons in highly dispersive media
|
The problem of stability and spectrum of linear excitations of a soliton (kink) of the dispersive sine-Gordon and $\varphi^4$ - equations is solved exactly. It is shown that the total spectrum consists of a discrete set of frequencies of internal modes and a single band spectrum of continuum waves. It is indicated by numerical simulations that a translation motion of a single soliton in the highly dispersive systems is accompanied by the arising of its internal dynamics and, in some cases, creation of breathers, and always by generation of the backward radiation. It is shown numerically that a fast motion of two topological solitons leads to a formation of the bound soliton complex in the dispersive sine-Gordon system.
|
[
"Physics Archive->nlin->nlin.PS"
] | 2020-07-02T09:36:02Z |
1504.06087
|
A divisibility result on combinatorics of generalized braids
|
For every finite Coxeter group $\Gamma$, each positive braids in the corresponding braid group admits a unique decomposition as a finite sequence of elements of $\Gamma$, the so-called Garside-normal form.The study of the associated adjacency matrix $Adj(\Gamma)$ allows to count the number of Garside-normal form of a given length.In this paper we prove that the characteristic polynomial of $Adj(B_n)$ divides the one of $Adj(B_{n+1})$. The key point is the use of a Hopf algebra based on signed permutations. A similar result was already known for the type $A$. We observe that this does not hold for type $D$. The other Coxeter types ($I$, $E$, $F$ and $H$) are also studied.
|
[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.GR"
] | 2015-04-23T08:50:58Z |
2306.10417
|
Amending the Lonely Runner Spectrum Conjecture
|
Let $\|x\|$ be the absolute distance from $x$ to the nearest integer. For a set of distinct positive integral speeds $v_1, \ldots, v_n$, we define its maximum loneliness to be $$\text{ML}(v_1,\ldots,v_n) = \max_{t \in \mathbb{R}}\min_{1 \leq i \leq n} \|tv_i\|$$ The Loneliness Spectrum Conjecture, recently proposed by Kravitz, asserts that $$\exists s \in \mathbb{N}, \text{ML}(v_1,\ldots,v_n) = \frac{s} {sn + 1} \text{ or } \text{ML}(v_1,\ldots,v_n) \ge \frac{1}{n}$$ We disprove the Loneliness Spectrum Conjecture for $n = 4$ and propose an alternative conjecture. We confirm the amended conjecture for $n = 4$ if any pair of speeds share a common factor of at least $3$ and also prove some related results.
|
[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.NT"
] | 2023-06-17T20:19:23Z |
astro-ph/0010508
|
Deprojection Galaxy Cluster X-ray, Sunyaev-Zel'dovich Temperature Decrement and Weak Lensing Mass Maps
|
A general method of deprojecting two-dimensional images to reconstruct the three dimensional structure of the projected object --specifically X-ray, Sunyaev-Zel'dovich (SZ) and gravitational lensing maps of rich clusters of galaxies -- assuming axial symmetry (Zaroubi et. al. 98), is considered. Here we test the applicability of the method for realistic, numerically simulated galaxy clusters, viewed from three orthogonal projections at four redshift outputs. We demonstrate that the assumption of axial symmetry is a good approximation for the 3D structure in this ensemble of galaxy clusters. Applying the method, we demonstrate that a unique determination of the cluster inclination angle is possible from comparison between the SZ and X-ray images and, independently, between SZ and surface density maps. Moreover, the results from these comparisons are found to be consistent with each other and with the full 3D structure inclination angle determination. The radial dark matter and gas density profiles as calculated from the actual and reconstructed 3D distributions show a very good agreement. The method is also shown to provide a direct determination of the baryon fraction in clusters, independent of the cluster inclination angle.
|
[
"Physics Archive->astro-ph"
] | 2000-10-25T10:05:55Z |
2209.06483
|
Exact controllability of the vortex system by means of a single vortex
|
In this paper, we investigate the controllability of the point vortex system by means of a single vortex. The point vortex system is a well-known simplied model for the incompressible Euler equation, where the vorticity is concentrated in a nite number of Dirac masses. We use one of the vortices as a control, and prove that by suitably choosing its trajectory, we can drive all other vortices to a given prescribed position in arbitrary time.
|
[
"Mathematics Archive->math.OC"
] | 2022-09-14T08:32:55Z |
0806.1478
|
WASP-14b: 7.3 Mj transiting planet in an eccentric orbit
|
We report the discovery of a 7.3 Mjup exoplanet WASP-14b, one of the most massive transiting exoplanets observed to date. The planet orbits the tenth-magnitude F5V star USNO-B1 11118-0262485 with a period of 2.243752 days and orbital eccentricity e = 0.09. A simultaneous fit of the transit light curve and radial velocity measurements yields a planetary mass of 7.3+/-0.5 Mjup and a radius of 1.28+/-0.08 Rjup. This leads to a mean density of about 4.6 g/cm^3 making it densest transiting exoplanets yet found at an orbital period less than 3 days. We estimate this system to be at a distance of 160+/-20 pc. Spectral analysis of the host star reveals a temperature of 6475+/-100 K, log g = 4.07 cm/s^2 and vsin i = 4.9+/-1.0 km/s, and also a high lithium abundance, log N(Li} = 2.84+/-0.05. The stellar density, effective temperature and rotation rate suggest an age for the system of about 0.5-1.0 Gyr.
|
[
"Physics Archive->astro-ph"
] | 2008-06-09T15:44:33Z |
2206.12560
|
On Attack-Resilient Service Placement and Availability in Edge-enabled IoV Networks
|
Achieving network resilience in terms of attack tolerance and service availability is critically important for Internet of Vehicles (IoV) networks where vehicles require assistance in sensitive and safety-critical applications like driving. It is particularly challenging in time-varying conditions of IoV traffic. In this paper, we study an attack-resilient optimal service placement problem to ensure disruption-free service availability to the users in edge-enabled IoV network. Our work aims to improve the user experience while minimizing the delay and simultaneously considering efficient utilization of limited edge resources. First, an optimal service placement is performed while considering traffic dynamicity and meeting the service requirements with the use of a deep reinforcement learning (DRL) framework. Next, an optimal secondary mapping and service recovery placements are performed to account for the attacks/failures at the edge. The use of DRL framework helps to adapt to dynamically varying IoV traffic and service demands. In this work, we develop three ILP models and use them in the DRL-based framework to provide attack-resilient service placement and ensure service availability with efficient network performance. Extensive numerical experiments are performed to demonstrate the effectiveness of the proposed approach.
|
[
"Computer Science Archive->cs.NI"
] | 2022-06-25T05:34:16Z |
2301.06448
|
The Balanced Matrix Factorization for Computational Drug Repositioning
|
Computational drug repositioning aims to discover new uses of drugs that have been marketed. However, the existing models suffer from the following limitations. Firstly, in the real world, only a minority of diseases have definite treatment drugs. This leads to an imbalance in the proportion of validated drug-disease associations (positive samples) and unvalidated drug-disease associations (negative samples), which disrupts the optimization gradient of the model. Secondly, the existing drug representation does not take into account the behavioral information of the drug, resulting in its inability to comprehensively model the latent feature of the drug. In this work, we propose a balanced matrix factorization with embedded behavior information (BMF) for computational drug repositioning to address the above-mentioned shortcomings. Specifically, in the BMF model, we propose a novel balanced contrastive loss (BCL) to optimize the category imbalance problem in computational drug repositioning. The BCL optimizes the parameters in the model by maximizing the similarity between the target drug and positive disease, and minimizing the similarity between the target drug and negative disease below the margin. In addition, we designed a method to enhance drug representation using its behavioral information. The comprehensive experiments on three computational drug repositioning datasets validate the effectiveness of the above improvement points. And the superiority of BMF model is demonstrated by experimental comparison with seven benchmark models.
|
[
"Computer Science Archive->cs.CE"
] | 2023-01-16T14:39:18Z |
2009.11503
|
Stability of $\mathbb{Z}^2$ configurations in 3D
|
Inspired by the issue of stability of molecular structures, we investigate the strict minimality of point sets with respect to configurational energies featuring two- and three-body contributions. Our main focus is on characterizing those configurations which cannot be deformed without changing distances between first neighbors or angles formed by pairs of first neighbors. Such configurations are called {\it angle-rigid}. We tackle this question in the class of finite configurations in $\mathbb{Z}^2$, seen as planar three-dimensional point sets. A sufficient condition preventing angle-rigidity is presented. This condition is also proved to be necessary when restricted to specific subclasses of configurations.
|
[
"Mathematics Archive->math.CO"
] | 2020-09-24T06:13:35Z |
math/0303176
|
Method of Hidden Parameters and Pell's Equation
|
Using the representation of numbers, the methods of decreasing the number of calculation steps for Pell's equation are developed. The formulae relating the natural solution x0 of Pell's equation for A0 with the infinite number of minimal natural solutions xi for other Ai are obtained for various cases. The parametric representation of Pell's equation solutions are obtained with the help of new "method of hidden parameters".
|
[
"Mathematics Archive->math.NT"
] | 2003-03-14T07:05:06Z |
hep-ph/9703381
|
Future Directions in Higgs Phenomenology
|
The search for the weakly-coupled Higgs sector at future colliders consists of three phases: discovery of a Higgs candidate, verification of the Higgs interpretation of the signal, and precision measurements of Higgs sector properties. The discovery of one Higgs boson with Standard Model properties is not sufficient to expose the underlying structure of the electroweak symmetry breaking dynamics. It is critical to search for evidence for a non-minimal Higgs sector and/or new physics associated with electroweak symmetry breaking dynamics.
|
[
"Physics Archive->hep->hep-ph"
] | 1997-03-21T09:15:09Z |
1804.07880
|
Laser Annealing for Radiatively Broadened MoSe2 grown by Chemical Vapor Deposition
|
We report on a laser annealing procedure which greatly improves the quality of suspended monolayers of chemical vapor deposition (CVD) grown MoSe2. Annealing with a green laser locally heats the suspended flake to approximately 600 K, which both removes contaminants and reduces strain gradients. At 4 K, we observe linewidths as narrow as 3.5 meV (1.6nm) full-width at half-max (FWHM) for both photoluminescence (PL) and reflection. Large peak reflectances up to 47% are also observed. These values are comparable to those of the highest quality hexagonal boron nitride (hBN) encapsulated samples. We demonstrate that this laser annealing process can yield highly spatially homogeneous samples, with the length scale of the homogeneity limited primarily by the size of the suspended area. Annealed regions are very stable, exhibiting negligible deterioration over 24 hours at cryogenic temperatures. The annealing method is also very repeatable, with substantial improvements of sample quality on every spot (> 40) tested.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2018-04-21T02:37:09Z |
quant-ph/0506249
|
Extended Jaynes-Cummings models and (quasi)-exact solvability
|
The original Jaynes-Cummings model is described by a Hamiltonian which is exactly solvable. Here we extend this model by several types of interactions leading to a nonhermitian operator which doesn't satisfy the physical condition of space-time reflection symmetry (PT symmetry). However the new Hamiltonians are either exactly solvable admitting an entirely real spectrum or quasi exactly solvable with a real algebraic part of their spectrum.
|
[
"Physics Archive->quant-ph"
] | 2005-06-29T10:02:52Z |
1603.04009
|
Pionic contribution in the Drell-Yan dilepton production cross section in p-Cu collision in the framework of the shell and Fermi gas models
|
To investigate the high mass dilepton production cross section produced due to the Drell-Yan process in hadronic collisions such as nucleon- nucleus, the valence and sea quarks distribution functions inside nucleus is used. In this study, in the framework of the shell and Fermi gas models, by adding quarks distribution functions of pions inside nucleus besides the quarks distribution functions of bound nucleons, the changes in the dilepton production cross section were investigated. For this reason, pionic contribution in the structure function of 63Cunucleus and its EMC ratio was first studied using the aforementioned models. Then, in the framework of the Drell-Yan process using GRV's nucleons and pions quarks distribution functions, the high mass dilepton production cross section in p-cu collision was calculated and compared with the available experimental data. The extracted results, based on the two mentioned models, were greatly the same and by considering the pionic contribution, the theoretical results were consistent with the experimental data.
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-th"
] | 2016-03-13T08:34:04Z |
1910.04888
|
Induced Fermionic vacuum polarization in dS spacetime with a compactified cosmic string
|
We study the fermionic condensate (FC) and the vacuum expectation value (VEV) of the energy-momentum tensor for a massive spinor field in the de Sitter (dS) spacetime including an ideal cosmic string. In addition, spatial dimension along the string is compactified to a circle of length $L$. The fermionic field is assumed to obey quasi-periodic condition along the $z$-axis. There are also magnetic fluxes running along the cosmic string and enclosed by the compact dimension. Both, the FC and the VEV of the energy-momentum tensor, are decomposed into two parts: one induced by the cosmic string in dS spacetime considering the absence of the compactification, and another one induced by the compactification. In particular, we show that the FC vanishes for a massless fermionic field.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2019-10-10T21:47:12Z |
2201.08686
|
Modelling Agent-Skipping Attacks in Message Forwarding Protocols
|
Message forwarding protocols are protocols in which a chain of agents handles transmission of a message. Each agent forwards the received message to the next agent in the chain. For example, TLS middleboxes act as intermediary agents in TLS, adding functionality such as filtering or compressing data. In such protocols, an attacker may attempt to bypass one or more intermediary agents. Such an agent-skipping attack can the violate security requirements of the protocol. Using the multiset rewriting model in the symbolic setting, we construct a comprehensive framework of such path protocols. In particular, we introduce a set of security goals related to path integrity: the notion that a message faithfully travels through participants in the order intended by the initiating agent. We perform a security analysis of several such protocols, highlighting key attacks on modern protocols.
|
[
"Computer Science Archive->cs.CR"
] | 2022-01-21T13:21:28Z |
hep-th/9410220
|
Finite-Difference Equations in Relativistic Quantum Mechanics
|
Relativistic Quantum Mechanics suffers from structural problems which are traced back to the lack of a position operator $\hat{x}$, satisfying $[\hat{x},\hat{p}]=i\hbar\hat{1}$ with the ordinary momentum operator $\hat{p}$, in the basic symmetry group -- the Poincar\'e group. In this paper we provide a finite-dimensional extension of the Poincar\'e group containing only one more (in 1+1D) generator $\hat{\pi}$, satisfying the commutation relation $[\hat{k},\hat{\pi}]=i\hbar\hat{1}$ with the ordinary boost generator $\hat{k}$. The unitary irreducible representations are calculated and the carrier space proves to be the set of Shapiro's wave functions. The generalized equations of motion constitute a simple example of exactly solvable finite-difference set of equations associated with infinite-order polarization equations.
|
[
"Physics Archive->hep->hep-th"
] | 1994-10-28T11:47:01Z |
1401.7404
|
On Index Coding in Noisy Broadcast Channels with Receiver Message Side Information
|
This letter investigates the role of index coding in the capacity of AWGN broadcast channels with receiver message side information. We first show that index coding is unnecessary where there are two receivers; multiplexing coding and superposition coding are sufficient to achieve the capacity region. We next show that, for more than two receivers, multiplexing coding and superposition coding alone can be suboptimal. We give an example where these two coding schemes alone cannot achieve the capacity region, but adding index coding can. This demonstrates that, in contrast to the two-receiver case, multiplexing coding cannot fulfill the function of index coding where there are three or more receivers.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2014-01-29T03:34:57Z |
0910.1108
|
Influence of Ni/Mn cation order on the spin-phonon coupling in multifunctional La2NiMnO6 epitaxial films by polarized Raman spectroscopy
|
We report the influence of Ni/Mn ordering on the spin-phonon coupling in multifunctional La2NiMnO6. Three types of films with different levels of structural order, including long-range Ni/Mn cation order, cation disorder, and an admixture of the ordered and disordered phases, are compared by polarized micro-Raman spectroscopy and magnetometry. Each film displays a strong dependence on the polarization configuration and a unique set of Raman active phonon excitations. Long-range cation ordering results in the splitting of Raman active phonon peaks because of Brillouin zone folding and lowering symmetry. Phonon mode softening begins clearly at a distinct temperature for each sample revealing a strong spin-lattice interaction. It follows closely the magnetization curve in ordered films. Unlike the admixture and the ordered films, softening behavior is strongly suppressed in the cation-disordered films. These differences may be understood based on the variation in amplitude of the spin-spin correlation functions due to the local Ni/Mn cation ordering.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2009-10-06T20:48:25Z |
2111.10023
|
UFO: A UniFied TransfOrmer for Vision-Language Representation Learning
|
In this paper, we propose a single UniFied transfOrmer (UFO), which is capable of processing either unimodal inputs (e.g., image or language) or multimodal inputs (e.g., the concatenation of the image and the question), for vision-language (VL) representation learning. Existing approaches typically design an individual network for each modality and/or a specific fusion network for multimodal tasks. To simplify the network architecture, we use a single transformer network and enforce multi-task learning during VL pre-training, which includes the image-text contrastive loss, image-text matching loss, and masked language modeling loss based on the bidirectional and the seq2seq attention mask. The same transformer network is used as the image encoder, the text encoder, or the fusion network in different pre-training tasks. Empirically, we observe less conflict among different tasks and achieve new state of the arts on visual question answering, COCO image captioning (cross-entropy optimization) and nocaps (in SPICE). On other downstream tasks, e.g., image-text retrieval, we also achieve competitive performance.
|
[
"Computer Science Archive->cs.CV"
] | 2021-11-19T03:23:10Z |
1210.7883
|
On Weak Elimination of Hyperimaginaries and its Consequences
|
We analyze the notion of weak elimination of hyperimaginaries (WEHI) in simple theories. A key observation in the analysis is a characterization of WEHI in terms of forking dependence -- a condition we dub dependence-witnessed-by-imaginaries (DWIP). Generalizing results of [1] and [3], we show that in a simple theory with WEHI, forking and thorn-forking coincide. We also show that, conversely, the equivalence of independence and thorn-independence is (almost) sufficient for WEHI. Thus, the WEHI and the statement independence = thorn-independence are morally equivalent. As a further application of our technology, we demonstrate stable forking for 1-based theories of finite SU-rank that have WEHI.
|
[
"Mathematics Archive->math.LO"
] | 2012-10-30T01:48:48Z |
2005.03766
|
On Inexact Accelerated Proximal Gradient Methods with Relative Error Rules
|
One of the most popular and important first-order iterations that provides optimal complexity of the classical proximal gradient method (PGM) is the "Fast Iterative Shrinkage/Thresholding Algorithm" (FISTA). In this paper, two inexact versions of FISTA for minimizing the sum of two convex functions are studied. The proposed schemes inexactly solve their subproblems by using relative error criteria instead of exogenous and diminishing error rules. When the evaluation of the proximal operator is difficult, inexact versions of FISTA are necessary and the relative error rules proposed here may have certain advantages over previous error rules. The same optimal convergence rate of FISTA is recovered for both proposed schemes. Some numerical experiments are reported to illustrate the numerical behavior of the new approaches.
|
[
"Mathematics Archive->math.OC"
] | 2020-05-07T21:23:57Z |
1510.00671
|
Long-time behavior of the $\omega \to \alpha$ transition in shocked Zirconium: Interplay of nucleation and plastic deformation
|
We study the thermally activated, slow conversion of the hysteretically retained $\omega$ phase into stable $\alpha$ phase in recovered samples of shocked zirconium. The $\omega$-phase decays in time following an algebraic law, unlike the predictions of the nucleation-growth framework for first order transitions, and residual volume fractions of phases and dislocation densities are related by a power law. We propose an explanation for the annealing mechanism through coupled dynamics of dislocations and phase change. We find that the long-time behavior is controlled by the interplay of dislocations, shear fluctuations, and remnant volume fractions of phases, which lead to an algebraic decay in time. For late time, thermally activated quantities such as the dislocation mobility and nucleation rate set the timescale and control the algebraic behavior, respectively. At high enough temperatures this behavior is effectively indistinguishable from standard Avrami kinetics.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2015-10-02T18:14:01Z |
1301.2234
|
All-loop infrared-divergent behavior of most-subleading-color gauge-theory amplitudes
|
The infrared singularities of gravitational amplitudes are one-loop exact, in that higher-loop divergences are characterized by the exponential of the one-loop divergence. We show that the contributions to SU(N) gauge-theory amplitudes that are most-subleading in the 1/N expansion are also one-loop exact, provided that the dipole conjecture holds. Possible corrections to the dipole conjecture, beginning at three loops, could violate one-loop-exactness, though would still maintain the absence of collinear divergences. We also demonstrate a relation between L-loop four-point N=8 supergravity and most-subleading-color N=4 SYM amplitudes that holds for the two leading IR divergences, O(1/\epsilon^L) and O(1/\epsilon^{L-1}), but breaks down at O(1/\epsilon^{L-2}).
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 2013-01-10T20:05:54Z |
0803.0701
|
Spanning directed trees with many leaves
|
The {\sc Directed Maximum Leaf Out-Branching} problem is to find an out-branching (i.e. a rooted oriented spanning tree) in a given digraph with the maximum number of leaves. In this paper, we obtain two combinatorial results on the number of leaves in out-branchings. We show that - every strongly connected $n$-vertex digraph $D$ with minimum in-degree at least 3 has an out-branching with at least $(n/4)^{1/3}-1$ leaves; - if a strongly connected digraph $D$ does not contain an out-branching with $k$ leaves, then the pathwidth of its underlying graph UG($D$) is $O(k\log k)$. Moreover, if the digraph is acyclic, the pathwidth is at most $4k$. The last result implies that it can be decided in time $2^{O(k\log^2 k)}\cdot n^{O(1)}$ whether a strongly connected digraph on $n$ vertices has an out-branching with at least $k$ leaves. On acyclic digraphs the running time of our algorithm is $2^{O(k\log k)}\cdot n^{O(1)}$.
|
[
"Computer Science Archive->cs.DM",
"Computer Science Archive->cs.DS"
] | 2008-03-05T16:38:34Z |
quant-ph/0408176
|
Continuous ensembles and the $\chi$-capacity of infinite-dimensional channels
|
The paper is devoted to systematic study of the $\chi$-capacity (underlying the classical capacity) of infinite dimensional quantum channels. An essential feature of this case is the natural appearance of the input constraints and infinite, in general, ``continuous'' state ensembles, defined as probability measures on the set of all quantum states. By using compactness criteria from probability theory and operator theory it is shown that the set of all generalized ensembles with the average (barycenter) in a compact set of states is itself a compact subset of the set of all probability measures. With this in hand we give a sufficient condition for the existence of an optimal generalized ensemble for a constrained quantum channel. This condition can be verified in the case of Bosonic Gaussian channels with constrained mean energy. The importance of the above condition is shown by considering example of a constrained channel with no optimal generalized ensemble. In the case of convex constraints a characterization of the optimal generalized ensemble is obtained extending the `` maximal distance'' property.
|
[
"Physics Archive->quant-ph"
] | 2004-08-30T09:55:46Z |
quant-ph/9810072
|
Fluorescence control through multiple interference mechanisms
|
We discuss the spontaneous emission from a coherently prepared and microwave driven doublet of potentially closely spaced excited states to a common ground level. Multiple interference mechanisms are identified which may lead to fluorescence inhibition in well-separated regions of the spectrum or act jointly in cancelling the spontaneous emission. In addition to phase independent quantum interferences due to combined absorptions and emissions of driving field photons, we distinguish two competing phase dependent interference mechanisms as means of controlling the fluorescence. The indistinguishable quantum paths may involve the spontaneous emission from the same state of the doublet, originating from the two different components of the initial coherent superposition. Alternatively the paths involve a different spontaneous photon from each of two decaying states, necessarily with the same polarization. This makes these photons indistinguishable in principle within the uncertainty of the two decay rates. The phase dependence arises for both mechanisms because the interfering paths differ by an unequal number of stimulated absorptions and emissions of the microwave field photons.
|
[
"Physics Archive->quant-ph"
] | 1998-10-23T17:34:53Z |
2212.08293
|
Active Phase for the Stochastic Sandpile on Z
|
We prove that the critical value of the one-dimensional Stochastic Sandpile Model is less than one. This verifies a conjecture of Rolla and Sidoravicius.
|
[
"Mathematics Archive->math.MP",
"Mathematics Archive->math.PR",
"Physics Archive->math-ph"
] | 2022-12-16T06:05:02Z |
1109.4420
|
Collisions in young triple systems
|
We perform N-body simulations of young triple systems consisting of two low-mass companions orbiting around a significantly more massive primary. We find that, when the orbits of the companions are coplanar and not too widely separated, the chance of a collision between the two companions can be as high as 20 per cent. Collisions between one of the companions (always the less massive) and the primary can also occur in systems with unequal-mass companions. The chance of collisions is a few per cent in systems with more realistic initial conditions, such as with slightly non-coplanar orbits and unequal-mass companions. If the companions start widely separated then collision are very rare except in some cases when the total mass of the companions is large. We suggest that collisions between members of young multiple systems may explain some unusual young multiple systems such as apparently non-coeval companions.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2011-09-20T20:00:33Z |
1610.06585
|
Assessment of the Information Content of the Power Spectrum and Bispectrum
|
The covariance matrix of the matter and halo power spectrum and bispectrum are studied. Using a large suite of simulations, we find that the non-Gaussianity in the covariance is significant already at mildly nonlinear scales. We compute the leading disconnected non-Gaussian correction to the matter bispectrum covariance using perturbation theory, and find that the corrections result in good agreement in the mildly nonlinear regime. The shot noise contribution to the halo power spectrum and bispectrum covariance is computed using the Poisson model, and the model yields decent agreement with simulation results. However, when the shot noise is estimated from the individual realization, which is usually done in reality, we find that the halo covariance is substantially reduced and gets close to the Gaussian covariance. This is because most of the non-Gaussianity in the covariance arises from the fluctuations in the Poisson shot noise. We use the measured non-Gaussian covariance to access the information content of the power spectrum and bispectrum. The signal-to-noise ratio, S/N, of the matter and halo power spectrum levels off in the mildly nonlinear regime, $k \sim 0.1 - 0.2 \,\mathrm{Mpc} h^{-1}$. In the nonlinear regime the S/N of the matter and halo bispectrum increases but much slower than the Gaussian results suggest. We find that both the S/N for power spectrum and bispectrum are overestimated by the Gaussian covariances, but the problem being much more serious for the bispectrum. Because the bispectrum is affected strongly by nonlinearity and shot noise, inclusion of the bispectrum only adds modest amount of S/N compared to that of the power spectrum.
|
[
"Physics Archive->astro-ph->astro-ph.CO"
] | 2016-10-20T20:00:13Z |
hep-th/9810219
|
Gauge Bundles and Born-Infeld on the Noncommutative Torus
|
In this paper, we describe non-abelian gauge bundles with magnetic and electric fluxes on higher dimensional noncommutative tori. We give an explicit construction of a large class of bundles with nonzero magnetic 't Hooft fluxes. We discuss Morita equivalence between these bundles. The action of the duality is worked out in detail for the four-torus. As an application, we discuss Born-Infeld on this torus, as a description of compactified string theory. We show that the resulting theory, including the fluctuations, is manifestly invariant under the T-duality group SO(4,4;Z). The U-duality invariant BPS mass-formula is discussed shortly. We comment on a discrepancy of this result with that of a recent calculation.
|
[
"Physics Archive->hep->hep-th"
] | 1998-10-27T13:50:09Z |
2306.14422
|
The Singing Voice Conversion Challenge 2023
|
We present the latest iteration of the voice conversion challenge (VCC) series, a bi-annual scientific event aiming to compare and understand different voice conversion (VC) systems based on a common dataset. This year we shifted our focus to singing voice conversion (SVC), thus named the challenge the Singing Voice Conversion Challenge (SVCC). A new database was constructed for two tasks, namely in-domain and cross-domain SVC. The challenge was run for two months, and in total we received 26 submissions, including 2 baselines. Through a large-scale crowd-sourced listening test, we observed that for both tasks, although human-level naturalness was achieved by the top system, no team was able to obtain a similarity score as high as the target speakers. Also, as expected, cross-domain SVC is harder than in-domain SVC, especially in the similarity aspect. We also investigated whether existing objective measurements were able to predict perceptual performance, and found that only few of them could reach a significant correlation.
|
[
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.SD",
"Electrical Engineering and Systems Science Archive->eess.AS"
] | 2023-06-26T05:04:58Z |
2210.14346
|
New wrapper method based on normalized mutual information for dimension reduction and classification of hyperspectral images
|
Feature selection is one of the most important problems in hyperspectral images classification. It consists to choose the most informative bands from the entire set of input datasets and discard the noisy, redundant and irrelevant ones. In this context, we propose a new wrapper method based on normalized mutual information (NMI) and error probability (PE) using support vector machine (SVM) to reduce the dimensionality of the used hyperspectral images and increase the classification efficiency. The experiments have been performed on two challenging hyperspectral benchmarks datasets captured by the NASA's Airborne Visible/Infrared Imaging Spectrometer Sensor (AVIRIS). Several metrics had been calculated to evaluate the performance of the proposed algorithm. The obtained results prove that our method can increase the classification performance and provide an accurate thematic map in comparison with other reproduced algorithms. This method may be improved for more classification efficiency. Keywords-Feature selection, hyperspectral images, classification, wrapper, normalized mutual information, support vector machine.
|
[
"Computer Science Archive->cs.CV"
] | 2022-10-25T21:17:11Z |
1304.7726
|
Universal valued fields and lifting points in local tropical varieties
|
Let $k$ be a field with a real valuation $\nu$ and $R$ a $k$-algebra. We show that there exist a $k$-algebra $K$ and a real valuation $\mu$ on $K$ extending $\nu$ such that any real ring valuation of $R$ is induced by $\mu$ via some homomorphism from $R$ to $K$; $K$ can be chosen to be a field. Then we study the case when $\nu$ is trivial and $R$ a complete local Noetherian ring with the residue field $k$. Let $K$ be the ring $\bar{k}[[t^\R]]$ of Hahn series with its natural valuation $\mu$; $\bar{k}$ is an algebraic closure of $k$. Despite $K$ is not universal in the strong sense defined above, it has the following weak universality property: for any local valuation $v$ and a finite set of elements $x_1,...,x_n$ of $R$ there exists a homomorphism $f\colon R\to K$ such that $v(x_i)=\mu(f(x_i))$, $i=1,...,n$. If $R=k[[x_1,...,x_n]]/I$ for an ideal $I$, this property implies that every point of the local tropical variety of $I$ lifts to a $K$-point of $R$. Similarly, if $R=k[x_1,...,x_n]/I$ is a finitely generated algebra over $k$, lifting points in the tropical variety of $I$ can be interpreted as the weak universality property of the field $\bar{k}((t^\R))$ of Hahn series.
|
[
"Mathematics Archive->math.AC",
"Mathematics Archive->math.AG"
] | 2013-04-29T17:59:53Z |
0902.2973
|
The History of Star Formation in Galaxies
|
If we are to develop a comprehensive and predictive theory of galaxy formation and evolution, it is essential that we obtain an accurate assessment of how and when galaxies assemble their stellar populations, and how this assembly varies with environment. There is strong observational support for the hierarchical assembly of galaxies, but by definition the dwarf galaxies we see today are not the same as the dwarf galaxies and proto-galaxies that were disrupted during the assembly. Our only insight into those disrupted building blocks comes from sifting through the resolved field populations of the surviving giant galaxies to reconstruct the star formation history, chemical evolution, and kinematics of their various structures. To obtain the detailed distribution of stellar ages and metallicities over the entire life of a galaxy, one needs multi-band photometry reaching solar-luminosity main sequence stars. The Hubble Space Telescope can obtain such data in the outskirts of Local Group galaxies. To perform these essential studies for a fair sample of the Local Universe will require observational capabilities that allow us to extend the study of resolved stellar populations to much larger galaxy samples that span the full range of galaxy morphologies, while also enabling the study of the more crowded regions of relatively nearby galaxies. With such capabilities in hand, we will reveal the detailed history of star formation and chemical evolution in the universe.
|
[
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.SR"
] | 2009-02-17T19:09:18Z |
1901.07221
|
Ergodic measures with infinite entropy
|
We construct ergodic probability measures with infinite metric entropy for typical continuous maps and homeomorphisms on compact manifolds. We also construct sequences of such measures that converge to a zero-entropy measure.
|
[
"Mathematics Archive->math.DS"
] | 2019-01-22T09:21:08Z |
1112.4070
|
Simulating protostellar evolution and radiative feedback in the cluster environment
|
Radiative feedback is among the most important consequences of clustered star formation inside molecular clouds. At the onset of star formation, radiation from massive stars heats the surrounding gas, which suppresses the formation of many low-mass stars. When simulating pre-main-sequence stars, their stellar properties must be defined by a prestellar model. Different approaches to prestellar modeling may yield quantitatively different results. In this paper, we compare two existing prestellar models under identical initial conditions to gauge whether the choice of model has any significant effects on the final population of stars. The first model treats stellar radii and luminosities with a ZAMS model, while separately estimating the accretion luminosity by interpolating to published prestellar tracks. The second, more accurate prestellar model self-consistently evolves the radius and luminosity of each star under highly variable accretion conditions. Each is coupled to a raytracing-based radiative feedback code that also treats ionization. The impact of the self-consistent model is less ionizing radiation and less heating during the early stages of star formation. This may affect final mass distributions. We noted a peak stellar mass reduced by 8% from 47.3 Msun to 43.5 Msun in the evolutionary model, relative to the track-fit model. Also, the difference in mass between the two largest stars in each case is reduced from 14 Msun to 7.5 Msun. The HII regions produced by these massive stars were also seen to flicker on timescales down to the limit imposed by our timestep (< 560 years), rapidly changing in size and shape, confirming previous cluster simulations using ZAMS-based estimates for prestellar ionizing flux.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2011-12-17T16:24:45Z |
1308.0459
|
Strange Mass Corrections to Hyperonic Semi-leptonic Decay in Statistical Model
|
The spin distributions, weak decay matrix elements for strange baryon octets with SU(3) breaking effects is studied. We systematically apply operator formalism along with statistical method to study JP= strange baryon octets for their low energy properties. Baryon is taken as an ensemble of quark-gluon Fock states in sea with three valence quarks to have spin-1/2, color-1 and flavor-8 quantum numbers. Detailed balance principle is applied to calculate the probabilities of each Fock states, with the inclusion of mass correction of strange quark in order to check the SU(3) breaking in weak decays constants and spin distributions. A dominant contribution from the vector sea is verified as compared to scalar and tensor sea, also the symmetry breaking correction leads to the deviations in the value of axial vector matrix elements ratio from experimental values by 17%. Present framework suggests a stronger base to choose statistical model with detailed balance principle to verify the experimental and theoretical values available and hence provide a deeper understanding to the strange baryon structure. Symmetry breaking effects lead to reduction in the values of axial matrix elements. Its contribution has a significant role in determining the validity of present approach.
|
[
"Physics Archive->hep->hep-ph"
] | 2013-08-02T10:44:43Z |
1705.10393
|
de Haas-van Alphen measurement of the antiferromagnet URhIn$_5$
|
We report on the results of a de Haas-van Alphen (dHvA) measurement performed on the recently discovered antiferromagnet URhIn$_5$ ($T_N$ = 98 K), a 5\textit{f}-analogue of the well studied heavy fermion antiferromagnet CeRhIn$_5$. The Fermi surface is found to consist of four surfaces: a roughly spherical pocket $\beta$, with $F_\beta \simeq 0.3$ kT; a pillow-shaped closed surface, $\alpha$, with $F_\alpha \simeq 1.1$ kT; and two higher frequencies $\gamma_1$ with $F_{\gamma_1} \simeq 3.2$ kT and $\gamma_2$ with $F_{\gamma_2} \simeq 3.5$ kT that are seen only near the \textit{c}-axis, and that may arise on cylindrical Fermi surfaces. The measured cyclotron masses range from 1.9 $m_e$ to 4.3 $m_e$. A simple LDA+SO calculation performed for the paramagnetic ground state shows a very different Fermi surface topology, demonstrating a need for more advanced electronic structure calculations.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2017-05-29T20:47:23Z |
nucl-th/9307003
|
The Single-Particle Spectral Function of $^{16}{\rm O}$
|
The influence of short-range correlations on the $p$-wave single-particle spectral function in $^{16}{\rm O}$ is studied as a function of energy. This influence, which is represented by the admixture of high-momentum components, is found to be small in the $p$-shell quasihole wave functions. It is therefore unlikely that studies of quasihole momentum distributions using the $(e,e'p)$ reaction will reveal a significant contribution of high momentum components. Instead, high-momentum components become increasingly more dominant at higher excitation energy. The above observations are consistent with the energy distribution of high-momentum components in nuclear matter.
|
[
"Physics Archive->nucl->nucl-th"
] | 1993-07-02T12:33:44Z |
hep-th/9903142
|
Glueball Mass Spectrum from Supergravity
|
We review the calculation of the spectrum of glueball masses in non-supersymmetric Yang-Mills theory using the conjectured duality between supergravity and large N gauge theories. The glueball masses are obtained by solving the supergravity wave equations in a black hole geometry. The glueball masses found this way are in unexpected agreement with the available lattice data. We also show how to use a modified version of the duality based on rotating branes to calculate the glueball mass spectrum with some of the Kaluza-Klein states of the supergravity theory decoupled from the spectrum.
|
[
"Physics Archive->hep->hep-lat",
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 1999-03-17T01:41:49Z |
1003.1374
|
The dilution peak, metallicity evolution, and dating of galaxy interactions and mergers
|
Strong inflows of gas from the outer disk to the inner kiloparsecs are induced during the interaction of disk galaxies. This inflow of relatively low-metallicity gas dilutes the metallicity of the circumnuclear gas. We have investigated several aspects of the process as the timing and duration of the dilution and its correlation with the induced star formation. We analysed major (1:1) gas-rich interactions and mergers, spanning a range of initial orbital characteristics. Star formation and metal enrichment from SNe are included in our model. Our results show that the strongest trend is between the star formation rate and the dilution of the metals in the nuclear region; i.e., the more intense the central burst of star formation, the more the gas is diluted. This trend comes from strong inflows of relatively metal-poor gas from the outer regions of both disks, which fuels the intense star formation and lowers the overall metallicity for a time. The strong inflows happen on timescales of about 10^8 years or less, and the most intense star formation and lowest gas phase metallicities are seen generally after the first pericentre passage. As the star formation proceeds and the merger advances, the dilution reduces and enrichment becomes dominant - ultimately increasing the metallicity of the circumnuclear gas to a level higher than the initial metallicities of the merging galaxies. The "fly-bys" - pairs that interact but do not merge - also cause some dilution. We even see some dilution early in the merger or in the "fly-bys" and thus do not observe a strong trend between the nuclear metallicities and separation in our simulations until the merger is well advanced. We also analyse the O and Fe enrichment of the ISM, and show that the evolution of the alpha/Fe ratios, as well as the dilution of the central gas metallicity, can be used as a clock for "dating" the interaction.
|
[
"Physics Archive->astro-ph->astro-ph.CO"
] | 2010-03-06T11:09:54Z |
hep-ex/0205018
|
Recent CDF and DO Run I Results
|
We summarize some of the the most recent CDF and DO results from the 1992-1995 collider run at the Fermilab Tevatron. These include a detailed examination of the heavy flavor content of W+jet data made by CDF.We found in this study that the rate and the kinematic properties of the event subsample, featuring soft lepton and secondary vertex in the same jet, are statistically difficult to accommodate with the Standard Model simulation. CDF has also searched for new physics in events with a photon, a lepton and missing transverse energy. Finally, the results of the two collaborations in their search for the first, second and third generations leptoquarks are presented.
|
[
"Physics Archive->hep->hep-ex"
] | 2002-05-09T23:08:35Z |
0709.1339
|
Control of Quantum Systems Despite Feedback Delay
|
Feedback control (based on the quantum continuous measurement) of quantum systems inevitably suffers from estimation delays. In this paper we give a delay-dependent stability criterion for a wide class of nonlinear stochastic systems including quantum spin systems. We utilize a semi-algebraic problem approach to incorporate the structure of density matrices. To show the effectiveness of the result, we derive a globally stabilizing control law for a quantum spin-1/2 systems in the face of feedback delays.
|
[
"Physics Archive->quant-ph"
] | 2007-09-10T14:03:21Z |
2006.09362
|
Solving polynomials with ordinary differential equations
|
In this work we consider a given root of a family of n-degree polynomials as a one-variable function that depends only on the independent term. Then we prove that this function satisfies several ordinary differential equations (ODE). More concretely, it satisfies several simple separated variables ODE, a first order generalized Abel ODE of degree n-1 and an (n-1)-th order linear ODE. Although some of our results are not new, our approach is simple and self-contained. For n=2, 3 and 4 we recover, from these ODE, the classical formulas for solving these polynomials.
|
[
"Mathematics Archive->math.CA"
] | 2020-06-16T17:55:46Z |
1810.05303
|
Parallelism in Randomized Incremental Algorithms
|
In this paper we show that many sequential randomized incremental algorithms are in fact parallel. We consider algorithms for several problems including Delaunay triangulation, linear programming, closest pair, smallest enclosing disk, least-element lists, and strongly connected components. We analyze the dependences between iterations in an algorithm, and show that the dependence structure is shallow with high probability, or that by violating some dependences the structure is shallow and the work is not increased significantly. We identify three types of algorithms based on their dependences and present a framework for analyzing each type. Using the framework gives work-efficient polylogarithmic-depth parallel algorithms for most of the problems that we study. This paper shows the first incremental Delaunay triangulation algorithm with optimal work and polylogarithmic depth, which is an open problem for over 30 years. This result is important since most implementations of parallel Delaunay triangulation use the incremental approach. Our results also improve bounds on strongly connected components and least-elements lists, and significantly simplify parallel algorithms for several problems.
|
[
"Computer Science Archive->cs.DS"
] | 2018-10-12T01:05:11Z |
2106.05047
|
Salient Object Ranking with Position-Preserved Attention
|
Instance segmentation can detect where the objects are in an image, but hard to understand the relationship between them. We pay attention to a typical relationship, relative saliency. A closely related task, salient object detection, predicts a binary map highlighting a visually salient region while hard to distinguish multiple objects. Directly combining two tasks by post-processing also leads to poor performance. There is a lack of research on relative saliency at present, limiting the practical applications such as content-aware image cropping, video summary, and image labeling. In this paper, we study the Salient Object Ranking (SOR) task, which manages to assign a ranking order of each detected object according to its visual saliency. We propose the first end-to-end framework of the SOR task and solve it in a multi-task learning fashion. The framework handles instance segmentation and salient object ranking simultaneously. In this framework, the SOR branch is independent and flexible to cooperate with different detection methods, so that easy to use as a plugin. We also introduce a Position-Preserved Attention (PPA) module tailored for the SOR branch. It consists of the position embedding stage and feature interaction stage. Considering the importance of position in saliency comparison, we preserve absolute coordinates of objects in ROI pooling operation and then fuse positional information with semantic features in the first stage. In the feature interaction stage, we apply the attention mechanism to obtain proposals' contextualized representations to predict their relative ranking orders. Extensive experiments have been conducted on the ASR dataset. Without bells and whistles, our proposed method outperforms the former state-of-the-art method significantly. The code will be released publicly available.
|
[
"Computer Science Archive->cs.CV"
] | 2021-06-09T13:00:05Z |
2109.12161
|
Deep Neural Networks for Blind Image Quality Assessment: Addressing the Data Challenge
|
The enormous space and diversity of natural images is usually represented by a few small-scale human-rated image quality assessment (IQA) datasets. This casts great challenges to deep neural network (DNN) based blind IQA (BIQA), which requires large-scale training data that is representative of the natural image distribution. It is extremely difficult to create human-rated IQA datasets composed of millions of images due to constraints of subjective testing. While a number of efforts have focused on design innovations to enhance the performance of DNN based BIQA, attempts to address the scarcity of labeled IQA data remain surprisingly missing. To address this data challenge, we construct so far the largest IQA database, namely Waterloo Exploration-II, which contains 3,570 pristine reference and around 3.45 million singly and multiply distorted images. Since subjective testing for such a large dataset is nearly impossible, we develop a novel mechanism that synthetically assigns perceptual quality labels to the distorted images. We construct a DNN-based BIQA model called EONSS, train it on Waterloo Exploration-II, and test it on nine subject-rated IQA datasets, without any retraining or fine-tuning. The results show that with a straightforward DNN architecture, EONSS is able to outperform the very state-of-the-art in BIQA, both in terms of quality prediction performance and execution speed. This study strongly supports the view that the quantity and quality of meaningfully annotated training data, rather than a sophisticated network architecture or training strategy, is the dominating factor that determines the performance of DNN-based BIQA models. (Note: Since this is an ongoing project, the final versions of Waterloo Exploration-II database, quality annotations, and EONSS, will be made publicly available in the future when it culminates.)
|
[
"Computer Science Archive->cs.CV",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | 2021-09-24T19:48:52Z |
2107.06963
|
Increasing Faithfulness in Knowledge-Grounded Dialogue with Controllable Features
|
Knowledge-grounded dialogue systems are intended to convey information that is based on evidence provided in a given source text. We discuss the challenges of training a generative neural dialogue model for such systems that is controlled to stay faithful to the evidence. Existing datasets contain a mix of conversational responses that are faithful to selected evidence as well as more subjective or chit-chat style responses. We propose different evaluation measures to disentangle these different styles of responses by quantifying the informativeness and objectivity. At training time, additional inputs based on these evaluation measures are given to the dialogue model. At generation time, these additional inputs act as stylistic controls that encourage the model to generate responses that are faithful to the provided evidence. We also investigate the usage of additional controls at decoding time using resampling techniques. In addition to automatic metrics, we perform a human evaluation study where raters judge the output of these controlled generation models to be generally more objective and faithful to the evidence compared to baseline dialogue systems.
|
[
"Computer Science Archive->cs.CL"
] | 2021-07-14T19:52:12Z |
0908.2651
|
Denouement of a Wormhole-Brane Encounter
|
Higher-dimensional black holes have long been considered within the context of brane worlds. Recently, it was shown that the brane-world ethos also permits the consideration of higher-dimensional wormholes. When such a wormhole, preexisting in the bulk, impinges upon our universe, taken to be a positive-tension 3-brane, it can induce the creation in our universe of a wormhole of ordinary dimensionality. The throat of this wormhole might fully constrict, pinch off, and thus birth a baby universe. Alternatively, the induced wormhole might persist. I show that persistence is more likely and note that the persistent wormhole manifests as a particle-like object whose interaction with cosmic matter is purely gravitational. I consider briefly the viability of this object as a dark matter candidate.
|
[
"Physics Archive->gr-qc"
] | 2009-08-18T22:30:36Z |
hep-th/9612098
|
Notes on SL(2) conformal fields theories. Exact solution and applications
|
In these notes I briefly outline SL(2) degenerate conformal field theories and their application to some related models, namely 2d gravity and N=2 discrete superconformal series.
|
[
"Physics Archive->hep->hep-th"
] | 1996-12-10T08:43:04Z |
1310.5083
|
Mean ergodic properties of the continuous Ces\`aro operators
|
Various properties of the (continuous) Ces\`aro operator $\mathsf{C}$, acting on Banach and Fr\'echet spaces of continuous functions and $L^p$-spaces, are investigated. For instance, the spectrum and point spectrum of $\mathsf{C}$ are completely determined and a study of certain dynamics of $\mathsf{C}$ is undertaken (eg. hyper- and supercyclicity, chaotic behaviour). In addition, the mean (and uniform mean) ergodic nature of $\mathsf{C}$ acting in the various spaces is identified.
|
[
"Mathematics Archive->math.FA"
] | 2013-10-18T16:35:45Z |
1606.03060
|
Network as a Service: The New Vista of Opportunities
|
The networking industry, compared to the compute industry, has been slow in evolving from a closed ecosystem with limited abstractions to a more open ecosystem with well-defined sophisticated high level abstractions. This has resulted in an ossified Internet architecture that inhibits innovation and is unnecessarily complex. Fortunately, there has been an exciting flux of rapid developments in networking in recent times with prominent trends emerging that have brought us to the cusp of a major paradigm shift. In particular, the emergence of technologies such as cloud computing, software defined networking (SDN), and network virtualization are driving a new vision of `networking as a service' (NaaS) in which networks are managed flexibly and efficiently cloud computing style. These technologies promise to both facilitate architectural and technological innovation while also simplifying commissioning, orchestration, and composition of network services. In this article, we introduce our readers to these technologies. In the coming few years, the trends of cloud computing, SDN, and network virtualization will further strengthen each other's value proposition symbiotically and NaaS will increasingly become the dominant mode of commissioning new networks.
|
[
"Computer Science Archive->cs.NI"
] | 2016-06-09T18:48:58Z |
1910.06001
|
Federated Transfer Reinforcement Learning for Autonomous Driving
|
Reinforcement learning (RL) is widely used in autonomous driving tasks and training RL models typically involves in a multi-step process: pre-training RL models on simulators, uploading the pre-trained model to real-life robots, and fine-tuning the weight parameters on robot vehicles. This sequential process is extremely time-consuming and more importantly, knowledge from the fine-tuned model stays local and can not be re-used or leveraged collaboratively. To tackle this problem, we present an online federated RL transfer process for real-time knowledge extraction where all the participant agents make corresponding actions with the knowledge learned by others, even when they are acting in very different environments. To validate the effectiveness of the proposed approach, we constructed a real-life collision avoidance system with Microsoft Airsim simulator and NVIDIA JetsonTX2 car agents, which cooperatively learn from scratch to avoid collisions in indoor environment with obstacle objects. We demonstrate that with the proposed framework, the simulator car agents can transfer knowledge to the RC cars in real-time, with 27% increase in the average distance with obstacles and 42% decrease in the collision counts.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.LG",
"Computer Science Archive->cs.RO"
] | 2019-10-14T09:15:31Z |
2209.09510
|
Iterative Poisson Surface Reconstruction (iPSR) for Unoriented Points
|
Poisson surface reconstruction (PSR) remains a popular technique for reconstructing watertight surfaces from 3D point samples thanks to its efficiency, simplicity, and robustness. Yet, the existing PSR method and subsequent variants work only for oriented points. This paper intends to validate that an improved PSR, called iPSR, can completely eliminate the requirement of point normals and proceed in an iterative manner. In each iteration, iPSR takes as input point samples with normals directly computed from the surface obtained in the preceding iteration, and then generates a new surface with better quality. Extensive quantitative evaluation confirms that the new iPSR algorithm converges in 5-30 iterations even with randomly initialized normals. If initialized with a simple visibility based heuristic, iPSR can further reduce the number of iterations. We conduct comprehensive comparisons with PSR and other powerful implicit-function based methods. Finally, we confirm iPSR's effectiveness and scalability on the AIM@SHAPE dataset and challenging (indoor and outdoor) scenes. Code and data for this paper are at https://github.com/houfei0801/ipsr.
|
[
"Computer Science Archive->cs.GR"
] | 2022-09-20T06:56:59Z |
1203.3891
|
Superspace approach to the renormalization of the O'Raifeartaigh model up to the second order in the LDE parameter
|
We adopt a superspace/supergraph formalism to pursue the investigation of the structure of one- and two-loop divergences in the frame of the minimal O'Raifeartaigh model that realizes the F-term spontaneous supersymmetry breaking. The linear delta expansion(LDE) procedure is introduced and renormalization is carried out up to the second order in the LDE expansion parameter. In agreement with the nonrenormalization theorem for the (chiral/antichiral) matter potential of ${\mathcal N}=1, \ D=4$ supersymmetry, our explicit supergraph calculations confirm that only the K\"{a}hler potential is actually renomalized.
|
[
"Physics Archive->hep->hep-th"
] | 2012-03-17T20:15:40Z |
quant-ph/0503036
|
Pure superposition states of atoms generated by a bichromatic elliptically polarized filed
|
We find specific polarizations of components of a bichromatic field, which allow one to prepare pure superposition states of atoms, using the coherent population trapping effect. These $m$$-$$m$ states are prepared in the system of Zeeman substates of the ground-state hyperfine levels with arbitrary angular momenta $F_1$ and $F_2$. It is established that, in general case $m\ne 0$, the use of waves with elliptical polarizations ($\epsilon_1$$\perp$$\epsilon_2$ field configuration for alkali metal atoms) is necessary for the pure state preparation. We analytically show an unique advantage of the D1 line of alkali metal atoms, which consists in the possibility to generate pure $m$$-$$m$ states even in the absence of spectral resolution of the excited-state hyperfine levels, contrary to the D2 line.
|
[
"Physics Archive->physics->physics.atom-ph",
"Physics Archive->quant-ph"
] | 2005-03-03T14:05:39Z |
nlin/0404030
|
Discrete breathers for understanding reconstructive mineral processes at low temperatures
|
Reconstructive transformations in layered silicates need a high tem- perature in order to be observed. However, very recently, some systems have been found where transformation can be studied at temperatures 600 C below the lowest experimental results previously reported, including sol-gel methods. We explore the possible relation with the existence of intrinsic localized modes, known as discrete breathers. We construct a model for nonlinear vibrations within the cation layer, obtain their parameters and calculate them numerically, obtaining their energies. Their statistics shows that although there are far less breathers than phonons, there are much more above the activation energy, being therefore a good candidate to explain the reconstructive transformations at low temperature.
|
[
"Physics Archive->nlin->nlin.PS"
] | 2004-04-15T13:57:06Z |
math/0608351
|
Value distribution theoretical properties of the Gauss map of pseudo-algebraic minimal surfaces
|
In this thesis, we study value distribution theoretical properties of the Gauss map of pseudo-algebraic minimal surfaces in n-dimensional Euclidean space. After reviewing basic facts, we give estimates for the number of exceptional values and the totally ramified value numbers and the corresponding unicity theorems for them.
|
[
"Mathematics Archive->math.CV",
"Mathematics Archive->math.DG"
] | 2006-08-14T15:43:11Z |
2307.02826
|
Realization of the unidirectional amplification in a cavity magnonic system
|
We experimentally demonstrate the nonreciprocal microwave amplification using a cavity magnonic system, consisting of a passive cavity (i.e., the split-ring resonator), an active feedback circuit integrated with an amplifier, and a ferromagnetic spin ensemble (i.e., a yttrium-iron-garnet sphere). Combining the amplification provided by the active circuit and the nonreciprocity supported by the cavity magnonics, we implement a nonreciprocal amplifier with the functions of both unidirectional amplification and reverse isolation. The microwave signal is amplified by 11.5 dB in the forward propagating direction and attenuated in the reverse direction by -34.7 dB, giving an isolation ratio of 46.2 dB. Such a unidirectional amplifier can be readily employed in quantum technologies, where the device can simultaneously amplify the weak signal output by the quantum system and isolate the sensitive quantum system from the backscattered external noise. Also, it is promising to explore more functions and applications using a cavity magnonic system with real gain.
|
[
"Physics Archive->physics->physics.app-ph"
] | 2023-07-06T07:45:35Z |
0906.2876
|
Signatures of intrinsic Li depletion and Li-Na anti-correlation in the metal-poor globular cluster NGC6397
|
To alleviate the discrepancy between the prediction of the primordial lithium abundance in the universe and the abundances observed in Pop II dwarfs and subgiant stars, it has been suggested that the stars observable today have undergone photospheric depletion of Li. To constrain the nature of such depletion, we conduct a homogeneous analysis of a very large sample of stars in the metal-poor globular cluster NGC6397, covering well all evolutionary phases from below the main sequence turn-off to high up the red giant branch. Non-LTE Li abundances or abundance upper limits are obtained for all stars, and for a size-able sub-set of the targets also Na abundances are obtained. The sodium abundances are used to distinguish stars formed out of pristine material from stars formed out of material affected by pollution from a previous generation of more massive stars. The dwarfs, turn-off, and early subgiant stars form a thin abundance plateau, disrupted in the middle of the subgiant branch by the lithium dilution caused by the first dredge-up. A second steep abundance drop is seen at the red giant branch bump. The turn-off stars are more lithium-poor, by up to 0.1 dex, than subgiants that have not yet undergone dredge-up. In addition, hotter dwarfs are slightly more lithium-poor than cooler dwarfs, which may be a signature of the so-called Li dip in the cluster, commonly seen among PopI stars. A considerably large spread in Na abundance confirms that NGC6397 has suffered from intra-cluster pollution in its infancy and a limited number of Na-enhanced and Li-deficient stars strongly contribute to form a significant anti-correlation between the abundances of Na and Li. The inferred Li abundances are compared to predictions from stellar structure models including atomic diffusion and ad-hoc turbulence below the convection zone.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2009-06-16T09:14:39Z |
1910.09779
|
Bridging the Gap Between $f$-GANs and Wasserstein GANs
|
Generative adversarial networks (GANs) have enjoyed much success in learning high-dimensional distributions. Learning objectives approximately minimize an $f$-divergence ($f$-GANs) or an integral probability metric (Wasserstein GANs) between the model and the data distribution using a discriminator. Wasserstein GANs enjoy superior empirical performance, but in $f$-GANs the discriminator can be interpreted as a density ratio estimator which is necessary in some GAN applications. In this paper, we bridge the gap between $f$-GANs and Wasserstein GANs (WGANs). First, we list two constraints over variational $f$-divergence estimation objectives that preserves the optimal solution. Next, we minimize over a Lagrangian relaxation of the constrained objective, and show that it generalizes critic objectives of both $f$-GAN and WGAN. Based on this generalization, we propose a novel practical objective, named KL-Wasserstein GAN (KL-WGAN). We demonstrate empirical success of KL-WGAN on synthetic datasets and real-world image generation benchmarks, and achieve state-of-the-art FID scores on CIFAR10 image generation.
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2019-10-22T05:55:03Z |
0708.2739
|
Stabilization of an overloaded queueing network using measurement-based admission control
|
Admission control can be employed to avoid congestion in queueing networks subject to overload. In distributed networks the admission decisions are often based on imperfect measurements on the network state. This paper studies how the lack of complete state information affects the system performance by considering a simple network model for distributed admission control. The stability region of the network is characterized and it is shown how feedback signaling makes the system very sensitive to its parameters.
|
[
"Mathematics Archive->math.PR"
] | 2007-08-20T21:51:47Z |
2311.05318
|
Dark Dimension and Decaying Dark Matter Gravitons
|
We explore the cosmology of the Dark Dimension scenario taking into account perturbations in the linear regime. In the context of the Dark Dimension scenario, a natural candidate for dark matter in our universe is the excitations of a tower of massive spin-2 KK gravitons. These dark gravitons are produced in the early universe and decay to lighter KK gravitons during the course of cosmological evolution. The decay causes the average dark matter mass to decrease as the universe evolves. In addition, the kinetic energy liberated in each decay leads to a kick velocity for the dark matter particles leading to a suppression of structure formation. Using current CMB (Planck), BAO and cosmic shear (KiDS-1000) data, we put a bound on the dark matter kick velocity today $v_\mathrm{today} \leq 2.2 \times 10^{-4} c$ at 95\% CL. This leads to rather specific regions of parameter space for the dark dimension scenario. The combination of the experimental bounds from cosmology, astrophysics and table-top experiments lead to the range $l_5\sim 1- 10 \, \mu m$ for the size of the Dark Dimension. The Dark Dimension scenario is found to be remarkably consistent with current observations and provides signatures that are within reach of near-future experiments.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 2023-11-09T12:31:21Z |
0806.4662
|
On the statistical significance of temporal firing patterns in multi-neuronal spike trains
|
Repeated occurrences of serial firing sequences of a group of neurons with fixed time delays between neurons are observed in many experiments involving simultaneous recordings from multiple neurons. Such temporal patterns are potentially indicative of underlying microcircuits and it is important to know when a repeatedly occurring pattern is statistically significant. These sequences are typically identified through correlation counts, such as in the two-tape algorithm of Abeles and Gerstein. In this paper we present a method for deciding on the significance of such correlations by characterizing the influence of one neuron on another in terms of conditional probabilities and specifying our null hypothesis in terms of a bound on the conditional probabilities. This method of testing significance of correlation counts is more general than the currently available methods since under our null hypothesis we do not assume that the spiking processes of different neurons are independent. The structure of our null hypothesis also allows us to rank order the detected patterns in terms of the strength of interaction among the neurons constituting the pattern. We demonstrate our method of assessing significance on simulated spike trains involving inhomogeneous Poisson processes with strong interactions, where the correlation counts are obtained using the two-tape algorithm.
|
[
"Quantitative Biology Archive->q-bio.NC"
] | 2008-06-28T06:14:58Z |
2009.06984
|
An Abstract Machine for Strong Call by Value
|
We present an abstract machine that implements a full-reducing (a.k.a. strong) call-by-value strategy for pure $\lambda$-calculus. It is derived using Danvy et al.'s functional correspondence from Cr\'egut's KN by: (1) deconstructing KN to a call-by-name normalization-by-evaluation function akin to Filinski and Rohde's, (2) modifying the resulting normalizer so that it implements the right-to-left call-by-value function application, and (3) constructing the functionally corresponding abstract machine. This new machine implements a reduction strategy that subsumes the fireball-calculus variant of call by value studied by Accattoli et al. We describe the strong strategy of the machine in terms of a reduction semantics and prove the correctness of the machine using a method based on Biernacka et al.'s generalized refocusing. As a byproduct, we present an example application of the machine to checking term convertibility by discriminating on the basis of their partially normalized forms.
|
[
"Computer Science Archive->cs.PL"
] | 2020-09-15T11:03:04Z |
2303.16378
|
A Pilot Study of Query-Free Adversarial Attack against Stable Diffusion
|
Despite the record-breaking performance in Text-to-Image (T2I) generation by Stable Diffusion, less research attention is paid to its adversarial robustness. In this work, we study the problem of adversarial attack generation for Stable Diffusion and ask if an adversarial text prompt can be obtained even in the absence of end-to-end model queries. We call the resulting problem 'query-free attack generation'. To resolve this problem, we show that the vulnerability of T2I models is rooted in the lack of robustness of text encoders, e.g., the CLIP text encoder used for attacking Stable Diffusion. Based on such insight, we propose both untargeted and targeted query-free attacks, where the former is built on the most influential dimensions in the text embedding space, which we call steerable key dimensions. By leveraging the proposed attacks, we empirically show that only a five-character perturbation to the text prompt is able to cause the significant content shift of synthesized images using Stable Diffusion. Moreover, we show that the proposed target attack can precisely steer the diffusion model to scrub the targeted image content without causing much change in untargeted image content. Our code is available at https://github.com/OPTML-Group/QF-Attack.
|
[
"Computer Science Archive->cs.CV"
] | 2023-03-29T01:24:25Z |
2307.15922
|
Distributed Traffic Engineering in Hybrid Software Defined Networks: A Multi-agent Reinforcement Learning Framework
|
Traffic Engineering (TE) is an efficient technique to balance network flows and thus improves the performance of a hybrid Software Defined Network (SDN). Previous TE solutions mainly leverage heuristic algorithms to centrally optimize link weight setting or traffic splitting ratios under the static traffic demand. Note that as the network scale becomes larger and network management gains more complexity, it is notably that the centralized TE methods suffer from a high computation overhead and a long reaction time to optimize routing of flows when the network traffic demand dynamically fluctuates or network failures happen. To enable adaptive and efficient routing in TE, we propose a Multi-agent Reinforcement Learning method CMRL that divides the routing optimization of a large network into multiple small-scale routing decisionmaking problems. To coordinate the multiple agents for achieving a global optimization goal, we construct an interactive environment for training the routing agents that own partial link utilization observations. To optimize credit assignment of multi-agent, we introduce the difference reward assignment mechanism for encouraging agents to take better action. Extensive simulations conducted on the real traffic traces demonstrate the superiority of CMRL in improving TE performance, especially when traffic demands change or network failures happen.
|
[
"Computer Science Archive->cs.NI"
] | 2023-07-29T07:39:55Z |
1507.07355
|
Magnetic upflow events in the quiet-Sun photosphere. I. Observations
|
Rapid magnetic upflows in the quiet-Sun photosphere were recently uncovered from both SUNRISE/IMaX and Hinode/SOT observations. Here, we study magnetic upflow events (MUEs) from high-quality, high- (spatial, temporal, and spectral) resolution, and full Stokes observations in four photospheric magnetically sensitive Fe I lines centered at 525.021, 617.334, 630.151, and 630.250 nm acquired with the Swedish Solar Telescope (SST)/CRISP. We detect MUEs by subtracting in-line Stokes V signals from those in far blue wing whose signal-to-noise ratio (S/N) >= 7. We find a larger number of MUEs at any given time (0.02 per square arcsec), larger by one to two orders of magnitude, than previously reported. The MUEs appear to fall into four classes presenting different shapes of Stokes V profiles with (I) asymmetric double lobes, (II) single lobes, (III) double-humped (two same-polarity lobes), and (IV) three lobes (an extra blue-shifted bump in addition to double-lobes), of which less than half are single-lobed. We also find that MUEs are almost equally distributed in network and internetwork areas and they appear in the interior or at the edge of granules in both regions. Distributions of physical properties, except that of horizontal velocity, of the MUEs (namely, Stokes V signal, size, line-of-sight velocity, and lifetime) are almost identical for the different spectral lines in our data. A bisector analysis of our spectrally resolved observations shows that these events host modest upflows and do not show direct indication of the presence of supersonic upflows reported earlier. Our findings reveal that numbers, types (classes), and properties determined for MUEs can strongly depend on the detection techniques used and the properties of the employed data, namely, S/Ns, resolutions, and wavelengths.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2015-07-27T10:32:45Z |
gr-qc/0204059
|
Braneworld Dynamics of Inflationary Cosmologies with Exponential Potentials
|
In this work we consider Randall-Sundrum braneworld type scenarios, in which the spacetime is described by a five-dimensional manifold with matter fields confined in a domain wall or three-brane. We present the results of a systematic analysis, using dynamical systems techniques, of the qualitative behaviour of Friedmann-Lemaitre-Robertson-Walker type models, whose matter is described by a scalar field with an exponential potential. We construct the state spaces for these models and discuss how their structure changes with respect to the general-relativistic case, in particular, what new critical points appear and their nature and the occurrence of bifurcation.
|
[
"Physics Archive->gr-qc"
] | 2002-04-18T05:29:35Z |
2303.14087
|
OPDMulti: Openable Part Detection for Multiple Objects
|
Openable part detection is the task of detecting the openable parts of an object in a single-view image, and predicting corresponding motion parameters. Prior work investigated the unrealistic setting where all input images only contain a single openable object. We generalize this task to scenes with multiple objects each potentially possessing openable parts, and create a corresponding dataset based on real-world scenes. We then address this more challenging scenario with OPDFormer: a part-aware transformer architecture. Our experiments show that the OPDFormer architecture significantly outperforms prior work. The more realistic multiple-object scenarios we investigated remain challenging for all methods, indicating opportunities for future work.
|
[
"Computer Science Archive->cs.CV"
] | 2023-03-24T15:52:20Z |
1109.4438
|
Quantum twistors
|
We compute explicitly a star product on the Minkowski space whose Poisson bracket is quadratic. This star product corresponds to a deformation of the conformal spacetime, whose big cell is the Minkowski spacetime. The description of Minkowski space is made in the twistor formalism and the quantization follows by substituting the classical conformal group by a quantum group.
|
[
"Mathematics Archive->math.QA",
"Physics Archive->hep->hep-th"
] | 2011-09-20T22:28:40Z |
1606.05486
|
On Lipschitz vector fields and the Cauchy problem in homogeneous groups
|
We introduce a class of "Lipschitz horizontal" vector fields in homogeneous groups, for which we show equivalent descriptions, e.g. in terms of suitable derivations. We then investigate the associated Cauchy problem, providing a uniqueness result both at equilibrium points and for vector fields of an involutive submodule of Lipschitz horizontal vector fields. We finally exhibit a counterexample to the general well-posedness theory for Lipschitz horizontal vector fields, in contrast with the Euclidean theory.
|
[
"Mathematics Archive->math.CA"
] | 2016-06-17T11:44:39Z |
2201.08943
|
Examining AGN UV/optical Variability Beyond the Simple Damped Random Walk
|
We present damped harmonic oscillator (DHO) light-curve modeling for a sample of 12,714 spectroscopically confirmed quasars in the Sloan Digital Sky Survey Stripe 82 region. DHO is a second-order continuous-time autoregressive moving-average (CARMA) process, which can be fully described using four independent parameters: a natural oscillation frequency ($\omega_{0}$), a damping ratio ($\xi$), a characteristic perturbation timescale ($\tau_{\mathrm{perturb}}$), and an amplitude for the perturbing white noise ($\sigma_{\mathrm{\epsilon}}$). The asymptotic variability amplitude of a DHO process is quantified by $\sigma_{\mathrm{DHO}}$ -- a function of $\omega_{0}$, $\xi$, $\tau_{\mathrm{perturb}}$, and $\sigma_{\mathrm{\epsilon}}$. We find that both $\tau_{\mathrm{perturb}}$ and $\sigma_{\mathrm{\epsilon}}$ follow different dependencies with rest-frame wavelength ($\lambda_{\mathrm{RF}}$) on either side of 2500 \AA, whereas $\sigma_{\mathrm{DHO}}$ follows a single power-law relation with $\lambda_{\mathrm{RF}}$. After correcting for wavelength dependence, $\sigma_{\mathrm{DHO}}$ exhibits anti-correlations with both the Eddington ratio and the black hole mass, while $\tau_{\mathrm{perturb}}$ -- with a typical value of days in the rest-frame -- shows an anti-correlation with the bolometric luminosity. Modeling AGN variability as a DHO offers more insight into the workings of accretion disks close to the supermassive black holes (SMBHs) at the center of AGN. The newly discovered short-term variability (characterized by $\tau_{\mathrm{perturb}}$ and $\sigma_{\mathrm{\epsilon}}$) and its correlation with bolometric luminosity pave the way for new algorithms that will derive fundamental properties (e.g., Eddington ratio) of AGN using photometric data alone.
|
[
"Physics Archive->astro-ph->astro-ph.GA"
] | 2022-01-22T02:02:58Z |
hep-lat/0406001
|
Leading Quenching Effects in the Proton Magnetic Moment
|
We present the first investigation of the extrapolation of quenched nucleon magnetic moments in quenched chiral effective field theory. We utilize established techniques in finite-range regularisation and compare with standard dimensional regularisation methods. Finite-volume corrections to the relevant loop integrals are also addressed. Finally, the contributions of dynamical sea quarks to the proton moment are estimated using a recently discovered phenomenological link between quenched and physical QCD.
|
[
"Physics Archive->hep->hep-lat",
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-th"
] | 2004-06-01T07:24:23Z |
1004.2317
|
Nonadiabatic geometric rotation of electron spin in a quantum dot by 2Pi hyperbolic secant pulses
|
In this paper, the geometric and dynamic phase components of overall phase induced by 2{\pi} hyperbolic secant pulses in a quantum dot is analyzed. The dependence of two phase components on the ratio of the Rabi frequency to the detuning is investigated. Numerical results indicate that only for one resonant pulse the induced overall phase is purely the geometric phase. With other values of the ratio the overall phase consists of a nonzero dynamic part. The effect of spin precession to decrease the dynamic phase is characterized and discussed by analytical and numerical techniques. Utilizing the symmetry relations of the phases, a scheme to eliminate the dynamic phase by multipulse control is proposed. By choosing the proper parameter for each pulse, the dynamic phases induced by different pulses cancel out. The total pure geometric phase varies from -{\pi} to {\pi}, which realizes the arbitrary geometric rotation of spin. Average fidelity is calculated and the effects of magnetic field and decay of the trion state are compared and discussed. The results show the crucial role of weak magnetic field for high fidelity (above 99.3%).
|
[
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->quant-ph"
] | 2010-04-14T05:15:59Z |
0810.3559
|
Metal-insulator transition in the Hartree-Fock phase diagram of the fully polarized homogeneous electron gas in two dimensions
|
We determine numerically the ground state of the two-dimensional, fully polarized electron gas within the Hartree-Fock approximation without imposing any particular symmetries on the solutions. At low electronic densities, the Wigner crystal solution is stable, but for higher densities ($r_s$ less than $\sim 2.7$) we obtain a ground state of different symmetry: the charge density forms a triangular lattice with about 11% more sites than electrons. We prove analytically that this conducting state with broken translational symmetry has lower energy than the uniform Fermi gas state in the high density region giving rise to a metal to insulator transition.
|
[
"Physics Archive->cond-mat->cond-mat.stat-mech",
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2008-10-20T14:00:37Z |
2109.04827
|
Analytical techniques for polarimetric imaging of accretion flows in Schwarzschild metric
|
Emission from an accretion disc around compact objects, such as neutron stars and black holes, is expected to be significantly polarized. The polarization can be used to put constraints on geometrical and physical parameters of the compact sources -- their radii, masses and spins -- as well as to determine the orbital parameters. The radiation escaping from the innermost parts of the disc is strongly affected by the gravitational field of the compact object and relativistic velocities of the matter. The straightforward calculation of the observed polarization signatures involves computationally expensive ray-tracing technique. At the same time, having fast computational routines for direct data fitting becomes increasingly important in light of the currently observed images of the accretion flow around supermassive black hole in M87 by the Event Horizon Telescope, infrared polarization signatures coming from Sgr A*, as well as for the upcoming X-ray polarization measurements by the Imaging X-ray Polarimetry Explorer and enhanced X-ray Timing and Polarimetry mission. In this work, we obtain an exact analytical expression for the rotation angle of polarization plane in Schwarzschild metric accounting for the effects of light bending and relativistic aberration. We show that the calculation of the observed flux, polarization degree and polarization angle as a function of energy can be performed analytically with high accuracy using approximate light-bending formula, lifting the need for the pre-computed tabular models in fitting routines.
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2021-09-10T12:15:10Z |
2311.14623
|
On new divisibility properties of generalized central trinomial coefficients and Legendre polynomials
|
We present a new formula for the highest power of $a+b$ that divides the sum $B(n,m,a,b)=\sum_{k=0}^{n}\binom{n}{k}^m a^{n-k}b^k$ for the case $m=2$. By using this formula, we give complete 3-adic valuation for central Dellanoy numbers. Also, we find the highest power of an odd integer $x$ that divides Legendre's polynomial $P_{n}(x)$. By using the same idea, generalized trinomial coefficients and generalized Motzkin numbers are treated. As a result, we give complete 3-adic valuation for little Schr\"{o}der numbers and restricted hexagonal numbers. By using new class of binomial sums, we examine divisibility of $B(n,m, a,b)$ by powers of $a+b$ for $m >2$.
|
[
"Mathematics Archive->math.NT"
] | 2023-11-24T17:37:33Z |
1209.6061
|
A UV complete model of Large N Thermal QCD
|
Many recent works on large N holographic QCD in the planar limit have not considered UV completions, restricting exclusively towards analyzing the IR physics. Due to this, the UV problems like Landau poles and divergences of Wilson loops including instabilities at high temperatures have not been addressed. In some of our recent papers, we have discussed a possible UV completion, which is conformal in the UV and confining in the far IR, that avoids the Landau poles and the Wilson loop divergences. In this paper we give a field theory realization of this including the complete RG flow. We extend our UV complete model to study scenarios both above and below the deconfinement temperature and argue how phase transition in our model should be understood. Interestingly, because of the UV completion, subtle issues like instability due to negative specific heat do not appear. We also briefly elucidate the advantages that our model may have over other models studying large N thermal QCD.
|
[
"Physics Archive->hep->hep-th"
] | 2012-09-26T20:01:38Z |
2106.06127
|
Differentially Private Federated Learning via Inexact ADMM
|
Differential privacy (DP) techniques can be applied to the federated learning model to protect data privacy against inference attacks to communication among the learning agents. The DP techniques, however, hinder achieving a greater learning performance while ensuring strong data privacy. In this paper we develop a DP inexact alternating direction method of multipliers algorithm that solves a sequence of subproblems with the objective perturbation by random noises generated from a Laplace distribution. We show that our algorithm provides $\bar{\epsilon}$-DP for every iteration, where $\bar{\epsilon}$ is a privacy parameter controlled by a user. Using MNIST and FEMNIST datasets for the image classification, we demonstrate that our algorithm reduces the testing error by at most $22\%$ compared with the existing DP algorithm, while achieving the same level of data privacy. The numerical experiment also shows that our algorithm converges faster than the existing algorithm.
|
[
"Computer Science Archive->cs.LG"
] | 2021-06-11T02:28:07Z |
hep-th/9508130
|
Random Walk with a Boundary Line as a Free Massive Boson with a Defect Line
|
We show that the problem of Random Walk with boundary attractive potential may be mapped onto the free massive bosonic Quantum Field Theory with a line of defect. This mapping permits to recover the statistical properties of the Random Walks by using boundary $S$--matrix and Form Factor techniques.
|
[
"Physics Archive->cond-mat",
"Physics Archive->hep->hep-th"
] | 1995-08-24T17:07:06Z |
1104.2858
|
On the center of the ring of differential operators on a smooth variety over $\bZ/p^n\bZ$
|
We compute the center of the ring of PD differential operators on a smooth variety over $\bZ/p^n\bZ$ confirming a conjecture of Kaledin. More generally, given an associative algebra $A_0$ over $\bF_p$ and its flat deformation $A_n$ over $\bZ/p^{n+1}\bZ$ we prove that under a certain non-degeneracy condition the center of $A_n$ is isomorphic to the ring of length $n+1$ Witt vectors over the center of $A_0$.
|
[
"Mathematics Archive->math.AG"
] | 2011-04-14T18:20:38Z |
1702.01392
|
Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter
|
An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->astro-ph->astro-ph.IM"
] | 2017-02-05T12:15:00Z |
2111.15644
|
Ultraviolet Observations of Comet 96/P Machholz at Perihelion
|
Ultraviolet spectra of Comet 96/P Machholz were obtained during its 2002 perihelion with the UVCS instrument aboard the SOHO satellite. Emission from H I, C II, C III, and O I, is detected near the nucleus. The outgassing rate is in line with the value extrapolated from rates at larger distances from the Sun, and abundances of C and O are estimated. Reconstructed images show a nearly spherical cloud in H I Ly$\alpha$ emission and an ion tail seen in C III. Radiation pressure on the hydrogen atoms produces a modest distortion of the shape of the Ly$\alpha$ cloud as seen from SOHO, and it produces Doppler shifts up to 30 km s$^{-1}$ in the outer parts of the cloud. We estimate a ratio of C to H$_2$O similar to what is observed in other comets, so low carbon abundance does not account for the anomalously low C$_2$ and C$_3$ ratios to NH$_2$ observed at optical wavelengths.
|
[
"Physics Archive->astro-ph->astro-ph.EP"
] | 2021-11-30T18:27:51Z |
hep-th/0008143
|
Loop integrals in three outstanding gauges: Feynman, Light-cone and Coulomb
|
We apply negative dimensional integration method (NDIM) to three outstanding gauges: Feynman, light-cone and Coulomb gauges. Our aim is to show that NDIM is a very suitable technique to deal with loop integrals, being them originated from any gauge choice. In Feynman gauge we perform scalar two-loop four-point massless integrals; in the light-cone gauge we calculate scalar two-loop integrals contributing for two-point functions without any kind of prescriptions, since NDIM can abandon such devices -- this calculation is the first test of our prescriptionless method beyond one-loop order; finally, for the Coulomb gauge we consider a four propagator massless loop integral, in the split dimensional regularization context.
|
[
"Physics Archive->hep->hep-th"
] | 2000-08-17T20:09:14Z |
2204.08079
|
On a conjecture of Harris
|
For $d \ge 4$, the Noether-Lefschetz locus $\mathrm{NL}_d$ parametrizes smooth, degree $d$ surfaces in $\mathbb{P}^3$ with Picard number at least $2$. A conjecture of Harris states that there are only finitely many irreducible components of the Noether-Lefschetz locus of non-maximal codimension. Voisin showed that the conjecture is false for sufficiently large $d$, but is true for $d \le 5$. She also showed that for $d=6, 7$, there are finitely many \emph{reduced}, irreducible components of $\mathrm{NL}_d$ of non-maximal codimension. In this article, we prove that for any $d \ge 6$, there are infinitely many \emph{non-reduced} irreducible components of $\mathrm{NL}_d$ of non-maximal codimension.
|
[
"Mathematics Archive->math.AG"
] | 2022-04-17T20:12:33Z |
1104.3067
|
Microtrap arrays on magnetic film atom chips for quantum information science
|
We present two different strategies for developing a quantum information science platform, based on our experimental results with magnetic microtrap arrays on a magnetic-film atom chip. The first strategy aims for mesoscopic ensemble qubits in a lattice of ~5 {\mu}m period, so that qubits can be individually addressed and interactions can be mediated by Rydberg excitations. The second strategy aims for direct quantum simulators using sub-optical lattices of ~100 nm period. These would allow the realization of condensed matter inspired quantum many-body systems, such as Hubbard models in new parameter regimes. The two approaches raise quite different issues, some of which are identified and discussed.
|
[
"Physics Archive->physics->physics.atom-ph",
"Physics Archive->quant-ph"
] | 2011-04-15T14:23:17Z |
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