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1906.11088 | Jupiter's Atmospheric Variability from Long-Term Ground-based Observations at 5 microns | Jupiter's banded structure undergoes strong temporal variations, changing the visible and infrared appearance of the belts and zones in a complex and turbulent way due to physical processes that are not yet understood. In this study we use ground-based 5-$\mu$m infrared data captured between 1984 and 2018 by 8 different instruments mounted on the Infrared Telescope Facility in Hawai'i and on the Very Large Telescope in Chile to analyze and characterize the long-term variability of Jupiter's cloud-forming region at the 1-4 bar pressure level. The data show a large temporal variability mainly at the equatorial and tropical latitudes, with a smaller temporal variability at mid-latitudes. We also compare the 5-$\mu$m-bright and -dark regions with the locations of the visible zones and belts and we find that these regions are not always co-located, specially in the southern hemisphere. We also present Lomb-Scargle and Wavelet Transform analyzes in order to look for possible periodicities of the brightness changes that could help us understand their origin and predict future events. We see that some of these variations occur periodically in time intervals of 4-8 years. The reasons of these time intervals are not understood and we explore potential connections to both convective processes in the deeper weather layer and dynamical processes in the upper troposphere and stratosphere. Finally we perform a Principal Component analysis to reveal a clear anticorrelation on the 5-$\mu$m brightness changes between the North Equatorial Belt and the South Equatorial Belt, suggesting a possible connection between the changes in these belts. | [
"Physics Archive->astro-ph->astro-ph.EP"
] | "2019-06-26T13:34:16Z" |
2308.13968 | Multivariate time series classification with dual attention network | One of the topics in machine learning that is becoming more and more relevant is multivariate time series classification. Current techniques concentrate on identifying the local important sequence segments or establishing the global long-range dependencies. They frequently disregard the merged data from both global and local features, though. Using dual attention, we explore a novel network (DA-Net) in this research to extract local and global features for multivariate time series classification. The two distinct layers that make up DA-Net are the Squeeze-Excitation Window Attention (SEWA) layer and the Sparse Self-Attention within Windows (SSAW) layer. DA- Net can mine essential local sequence fragments that are necessary for establishing global long-range dependencies based on the two expanded layers. | [
"Computer Science Archive->cs.LG"
] | "2023-08-26T22:47:46Z" |
2012.04248 | Generalization of the Secant Method for Nonlinear Equations (extended version) | The secant method is a very effective numerical procedure used for solving nonlinear equations of the form $f(x)=0$. It is derived via a linear interpolation procedure and employs only values of $f(x)$ at the approximations to the root of $f(x)=0$, hence it computes $f(x)$ only once per iteration. In this note, we generalize it by replacing the relevant linear interpolant by a suitable $(k+1)$-point polynomial of interpolation, where $k$ is an integer at least 2. Just as the secant method, this generalization too enjoys the property that it computes $f(x)$ only once per iteration. We provide its error in closed form and analyze its order of convergence $s_k$. We show that this order of convergence is greater than that of the secant method, and it increases towards $2$ as $k\to \infty$. (Indeed, $s_7=1.9960\cdots$, for example.) This is true for the efficiency index of the method too. We also confirm the theory via an illustrative example. | [
"Computer Science Archive->cs.NA",
"Mathematics Archive->math.NA"
] | "2020-12-08T07:01:50Z" |
2001.11286 | Self-assembly of finite-sized colloidal aggregates | One of the challenges of self-assembling finite-sized colloidal aggregates with a sought morphology is the necessity of precisely sorting the position of the colloids at the microscopic scale to avoid the formation of off-target structures. Microfluidic platforms address this problem by loading into single droplets the exact amount of colloids entering the targeted aggregate. Using theory and simulations, in this paper, we validate a more versatile design allowing us to fabricate different types of finite-sized aggregates, including colloidal molecules or core-shell clusters, starting from finite density suspensions of isotropic colloids in bulk. In our model, interactions between particles are mediated by DNA linkers with mobile tethering points, as found in experiments using DNA oligomers tagged with hydrophobic complexes immersed into supported bilayers. By fine-tuning the strength and the number of the different types of linkers, we prove the possibility of controlling the morphology of the aggregates, in particular, the valency of the molecules and the size of the core-shell clusters. In general, our design shows how multivalent interactions can lead to microphase separation in equilibrium conditions. | [
"Physics Archive->cond-mat->cond-mat.soft",
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | "2020-01-30T12:50:17Z" |
1401.7085 | Reverse Edge Cut-Set Bounds for Secure Network Coding | We consider the problem of secure communication over a network in the presence of wiretappers. We give a new cut-set bound on secrecy capacity which takes into account the contribution of both forward and backward edges crossing the cut, and the connectivity between their endpoints in the rest of the network. We show the bound is tight on a class of networks, which demonstrates that it is not possible to find a tighter bound by considering only cut set edges and their connectivity. | [
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | "2014-01-28T04:49:20Z" |
1606.08055 | $R_{II}$ type recurrence, generalized eigenvalue problem and orthogonal polynomials on the unit circle | We consider a sequence of polynomials $\{P_n\}_{n \geq 0}$ satisfying a special $R_{II}$ type recurrence relation where the zeros of $P_n$ are simple and lie on the real line. It turns out that the polynomial $P_n$, for any $n \geq 2$, is the characteristic polynomial of a simple $n \times n$ generalized eigenvalue problem. It is shown that with this $R_{II}$ type recurrence relation one can always associate a positive measure on the unit circle. The orthogonality property satisfied by $P_n$ with respect to this measure is also obtained. Finally, examples are given to justify the results. | [
"Mathematics Archive->math.CA"
] | "2016-06-26T16:49:55Z" |
nucl-th/9712028 | Transitions between complex configurations in the excitation of the Double Giant Resonance | The transitions between complex configurations, to which the giant dipole resonance (GDR) and the double giant dipole resonance (DGDR) doorway states are coupled, are taken into account in second order perturbation theory for the reaction amplitude. It is proved that only transitions between GDR and DGDR doorway states play an essential role in the Coulomb excitation of the DGDR. | [
"Physics Archive->nucl->nucl-th"
] | "1997-12-08T11:52:45Z" |
1809.09272 | Nachman's reconstruction for the Calderon problem with discontinuous conductivities | We show that Nachman's integral equations for the Calder\'on problem, derived for conductivities in $W^{2,p}(\Omega)$, still hold for $L^\infty$ conductivities which are $1$ in a neighborhood of the boundary. We also prove convergence of scattering transforms for smooth approximations to the scattering transform of $L^\infty$ conductivities. We rely on Astala-P\"aiv\"arinta's formulation of the Calder\'on problem for a framework in which these convergence results make sense. | [
"Mathematics Archive->math.AP"
] | "2018-09-25T00:52:36Z" |
1708.07644 | Joint Structured Learning and Predictions under Logical Constraints in Conditional Random Fields | This paper is concerned with structured machine learning, in a supervised machine learning context. It discusses how to make joint structured learning on interdependent objects of different nature, as well as how to enforce logical con-straints when predicting labels. We explain how this need arose in a Document Understanding task. We then discuss a general extension to Conditional Random Field (CRF) for this purpose and present the contributed open source implementation on top of the open source PyStruct library. We evaluate its performance on a publicly available dataset. | [
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | "2017-08-25T08:14:22Z" |
2307.06688 | Aeolus Ocean -- A simulation environment for the autonomous COLREG-compliant navigation of Unmanned Surface Vehicles using Deep Reinforcement Learning and Maritime Object Detection | Heading towards navigational autonomy in unmanned surface vehicles (USVs) in the maritime sector can fundamentally lead towards safer waters as well as reduced operating costs, while also providing a range of exciting new capabilities for oceanic research, exploration and monitoring. However, achieving such a goal is challenging. USV control systems must, safely and reliably, be able to adhere to the international regulations for preventing collisions at sea (COLREGs) in encounters with other vessels as they navigate to a given waypoint while being affected by realistic weather conditions, either during the day or at night. To deal with the multitude of possible scenarios, it is critical to have a virtual environment that is able to replicate the realistic operating conditions USVs will encounter, before they can be implemented in the real world. Such "digital twins" form the foundations upon which Deep Reinforcement Learning (DRL) and Computer Vision (CV) algorithms can be used to develop and guide USV control systems. In this paper we describe the novel development of a COLREG-compliant DRL-based collision avoidant navigational system with CV-based awareness in a realistic ocean simulation environment. The performance of the trained autonomous Agents resulting from this approach is evaluated in several successful navigations to set waypoints in both open sea and coastal encounters with other vessels. A binary executable version of the simulator with trained agents is available at https://github.com/aavek/Aeolus-Ocean | [
"Computer Science Archive->cs.LG",
"Computer Science Archive->cs.RO"
] | "2023-07-13T11:20:18Z" |
hep-th/9410043 | The Mandelstam--Leibbrandt Prescription and the Discretized Light Front Quantization | It is shown that the quantization of the unphysical degrees of freedom, which leads to the Mandelstam--Leibbrandt prescription for the infrared spurious singularities in the continuum light cone gauge, does indeed suggest some quite natural recipe to treat the zero modes in the Discretized Light Front Quantization of gauge theories. | [
"Physics Archive->hep->hep-th"
] | "1994-10-07T11:14:34Z" |
1308.2882 | Towards experimental tests and applications of Lieb-Robinson bounds | Spin-polarized scanning tunneling microscopy is identified as a suitable experimental technique to investigate the quantitative quality of Lieb-Robinson bounds on the signal velocity. The latest, most general bound is simplified and it is shown that there is a discrepancy by a factor of approximately 4 between the corresponding limit speed and some estimated exact velocities in atomic spin chains. The observed discrepancy facilitates conclusions for a further mathematical improvement of Lieb-Robinson bounds. The real signal propagation can be modified with several experimental parameters from which the bounds are independent. This enables the application of Lieb-Robinson bounds as upper limits on the enhancement of the real signal speed for information transport in spintronic devices. | [
"Physics Archive->quant-ph"
] | "2013-08-13T14:41:16Z" |
nucl-th/0107058 | Charmonium absorption cross section by nucleon | The $J/\psi$ absorption cross section by nucleon is studied using a gauged SU(4) hadronic Lagrangian but with empirical particle masses, which has been used previously to study the $J/\psi$ absorption cross section by pion and rho meson. Including both two-body and three-body final states, we find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the $J/\psi-N$ absorption is at most 5 mb and is consistent with that extracted from $J/\psi$ production from both photo-nuclear and proton-nucleus reactions. | [
"Physics Archive->nucl->nucl-th"
] | "2001-07-23T21:15:26Z" |
1611.02700 | The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release | The LOFAR Two-metre Sky Survey (LoTSS) is a deep 120-168 MHz imaging survey that will eventually cover the entire Northern sky. Each of the 3170 pointings will be observed for 8 hrs, which, at most declinations, is sufficient to produce ~5arcsec resolution images with a sensitivity of ~0.1mJy/beam and accomplish the main scientific aims of the survey which are to explore the formation and evolution of massive black holes, galaxies, clusters of galaxies and large-scale structure. Due to the compact core and long baselines of LOFAR, the images provide excellent sensitivity to both highly extended and compact emission. For legacy value, the data are archived at high spectral and time resolution to facilitate subarcsecond imaging and spectral line studies. In this paper we provide an overview of the LoTSS. We outline the survey strategy, the observational status, the current calibration techniques, a preliminary data release, and the anticipated scientific impact. The preliminary images that we have released were created using a fully-automated but direction-independent calibration strategy and are significantly more sensitive than those produced by any existing large-area low-frequency survey. In excess of 44,000 sources are detected in the images that have a resolution of 25arcsec, typical noise levels of less than 0.5 mJy/beam, and cover an area of over 350 square degrees in the region of the HETDEX Spring Field (right ascension 10h45m00s to 15h30m00s and declination 45d00m00s to 57d00m00s). | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.IM"
] | "2016-11-08T19:18:26Z" |
0804.4030 | Infinitely many solution for prescribed curvature problem on $S^N$ | We consider the following prescribed scalar curvature problem on $ S^N$ (*)$$\left\{\begin{array}{l} - \Delta_{S^N} u + \frac{N(N-2)}{2} u = \tilde{K} u^{\frac{N+2}{N-2}} {on} S^N, u >0 \end{array}\right. $$ where $ \tilde{K}$ is positive and rotationally symmetric. We show that if $\tilde{K}$ has a local maximum point between the poles then equation (*) has {\bf infinitely many non-radial positive} solutions, whose energy can be made arbitrarily large. | [
"Mathematics Archive->math.AP"
] | "2008-04-25T01:18:59Z" |
0908.0312 | How Well Does AdS/QCD Describe QCD? | AdS/QCD is an extra-dimensional approach to modeling hadronic physics, motivated by the AdS/CFT correspondence in string theory. AdS/QCD models are often more accurate than would have been expected at energies below a few GeV. We address the question of why these models are so successful, and respond to some of the criticisms that have been waged against these models. | [
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | "2009-08-03T18:37:57Z" |
2307.12408 | Big mapping class groups are not extremely amenable | This paper uses the renowned Kechris-Pestov-Todor\v{c}evi\'{c} machinery to show that (big) mapping class groups are not extremely amenable unless the underlying surface is a sphere or a once-punctured sphere, or equivalently when the mapping class group is trivial. The same techniques also show that the pure mapping class groups, as well as compactly supported mapping class groups, of a surface with genus at least one can never be extremely amenable. | [
"Mathematics Archive->math.GR",
"Mathematics Archive->math.GT"
] | "2023-07-23T19:16:00Z" |
2311.05051 | Deep Learning Brasil at ABSAPT 2022: Portuguese Transformer Ensemble Approaches | Aspect-based Sentiment Analysis (ABSA) is a task whose objective is to classify the individual sentiment polarity of all entities, called aspects, in a sentence. The task is composed of two subtasks: Aspect Term Extraction (ATE), identify all aspect terms in a sentence; and Sentiment Orientation Extraction (SOE), given a sentence and its aspect terms, the task is to determine the sentiment polarity of each aspect term (positive, negative or neutral). This article presents we present our participation in Aspect-Based Sentiment Analysis in Portuguese (ABSAPT) 2022 at IberLEF 2022. We submitted the best performing systems, achieving new state-of-the-art results on both subtasks. | [
"Computer Science Archive->cs.CL"
] | "2023-11-08T22:58:34Z" |
1212.0359 | A pre-projective part of tilting quivers of certain path algebras | D.Happel and L.Unger defined a partial order on the set of basic tilting modules. We study the poset of basic pre-projective tilting modules over path algebra of infinite type. First we will give a criterion for Ext-vanishing for pre-projective modules. And by using this we will give a combinatorial characterization of the poset of basic pre-projective tilting modules. Finally we will see a structure of a pre-projective part of tilting quivers. | [
"Mathematics Archive->math.RA",
"Mathematics Archive->math.RT"
] | "2012-12-03T11:54:39Z" |
hep-ph/9711233 | Top Quark Pair Production and Decay Near Threshold in e+e- Collisions | We review the physics involved in the production and decay of top quarks in e^+e^- -> ttbar near threshold, with special emphasis on the recent theoretical study on the decay process of top quarks in the threshold region. The energy-angular distribution of l^+ in semileptonic top decays is calculated including the full O(alpha_s) corrections. Various effects of the final-state interactions are elucidated. A new observable is defined near threshold, which depends only on the decay of free polarized top quarks, and thus it can be calculated without bound-state effects or the final-state interactions. | [
"Physics Archive->hep->hep-ph"
] | "1997-11-04T17:11:40Z" |
1504.06041 | Eventually index of reducibility on sequentially Cohen-Macaulay modules | It is shown that a module is sequentially Cohen-Macaulay if and only if the index of reducibility for distinguished parameter ideals are eventually constant with special value. As corollaries to the main theorem we given to characterize the Gorensteinness, Cohen-Macaulayness of local rings in term of eventually index of reducibility for distinguished parameter ideals. | [
"Mathematics Archive->math.AC"
] | "2015-04-23T04:44:19Z" |
0712.1850 | Holographic Calculation of Boundary Entropy | We use the holographic proposal for calculating entanglement entropies to determine the boundary entropy of defects in strongly coupled two-dimensional conformal field theories. We study several examples including the Janus solution and show that the boundary entropy extracted from the entanglement entropy as well as its more conventional definition via the free energy agree with each other. Maybe somewhat surprisingly we find that, unlike in the case of a conformal field theory with boundary, the entanglement entropy for a generic region in a theory with defect carries detailed information about the microscopic details of the theory. We also argue that the g-theorem for the boundary entropy is closely related to the strong subadditivity of the entanglement entropy. | [
"Physics Archive->cond-mat->cond-mat.stat-mech",
"Physics Archive->hep->hep-th"
] | "2007-12-11T23:55:16Z" |
0812.4180 | Thermodynamics of the (2+1)-dimensional Black Hole with non linear Electrodynamics and without Cosmological Constant from the Generalized Uncertainly Principle | In this paper, we study the thermodynamical properties of the (2+1)dimensional black hole with a non-linear electrodynamics and without cosmological constant using the Generalized Uncertainty Principle (GUP). This approach shows that there is a maximum temperature for the black hole depending only on the electric charge and corresponding to the minimum radius of the event horizon, of the order of the Planck scale. Finally we show that the heat capacity for this black hole has the expected behavior. | [
"Physics Archive->gr-qc"
] | "2008-12-22T13:36:09Z" |
1601.00736 | Penalized Maximum Likelihood Estimation of Multi-layered Gaussian Graphical Models | Analyzing multi-layered graphical models provides insight into understanding the conditional relationships among nodes within layers after adjusting for and quantifying the effects of nodes from other layers. We obtain the penalized maximum likelihood estimator for Gaussian multi-layered graphical models, based on a computational approach involving screening of variables, iterative estimation of the directed edges between layers and undirected edges within layers and a final refitting and stability selection step that provides improved performance in finite sample settings. We establish the consistency of the estimator in a high-dimensional setting. To obtain this result, we develop a strategy that leverages the biconvexity of the likelihood function to ensure convergence of the developed iterative algorithm to a stationary point, as well as careful uniform error control of the estimates over iterations. The performance of the maximum likelihood estimator is illustrated on synthetic data. | [
"Statistics Archive->stat.ME"
] | "2016-01-05T05:08:33Z" |
1710.11614 | Remarks on R\'emond's generalized Lehmer problems | We draw connections between the various conjectures which are included in G. R\'emond's generalized Lehmer problems. Specifically, we show that the degree one form of his conjecture for the multiplicative group is, in a sense, almost as strong as the strong form. Our insights into the conjectures apply a basic result on what may be called Diophantine approximation in the metric induced by the canonical height. We also present a previously unpublished partial result of R\'emond on his conjectures. | [
"Mathematics Archive->math.NT"
] | "2017-10-31T17:44:18Z" |
1010.2995 | Production of light nuclei, hypernuclei and their antiparticles in relativistic nuclear collisions | We present, using the statistical model, an analysis of the production of light nuclei, hypernuclei and their antiparticles in central collisions of heavy nuclei. Based on these studies we provide predictions for the production yields of multiply-strange light nuclei. | [
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-th"
] | "2010-10-14T18:05:44Z" |
0810.3643 | NC Coherent pi0 Production Below 2 GeV | The single largest background to future $\bar{\nu_{\mu}}\to \bar{\nu_e}$ ($\nu_\mu \to \nu_e$) oscillation searches is neutral current (NC) $\pi^0$ production. MiniBooNE, which began taking antineutrino data in January 2006, has the world's largest sample of reconstructed $\pi^0$'s produced by antineutrinos. These neutral pions are primarily produced through the $\Delta$ resonance but can also be created through "coherent production." The latter process is the coherent sum of glancing scatters of antineutrinos off a neutron or proton, in which the nucleus is kept intact but a $\pi^0$ is created. A signature of this process is a $\pi^0$ which is highly forward-going. It is useful to study coherent production using antineutrinos rather than neutrinos because the ratio of coherent to resonant scattering is enhanced in antineutrino running. The measurement of NC coherent $\pi^0$ production in the MiniBooNE antineutrino data will be discussed. | [
"Physics Archive->hep->hep-ex"
] | "2008-10-20T19:49:53Z" |
0810.0134 | Structured jets and VHE emission of blazars and radiogalaxies | Recent observations in the TeV band challenge the simplest models developed to describe the overall emission of blazars and radiogalaxies. In particular, the observation of variable TeV emission from M87 and the fast variability shown by PKS 2155-304 challenge the standard framework. We discuss how the existence of a radial structure in the sub-pc scale jet, with faster a component ("spine" or "needles") embedded in a slower layer can explain the basic phenomenology of these sources. | [
"Physics Archive->astro-ph"
] | "2008-10-01T11:44:03Z" |
1201.0602 | Radiative transfer of energetic photons: X-rays and helium ionization in C2-Ray | We present an extension to the short-characteristic ray-tracing and non-equilibrium photon-ionization code C2Ray. The new version includes the effects of helium and improved multi-frequency heating. The motivation for this work is to be able to deal with harder ionizing spectra, such as for example from quasar-like sources during cosmic reionization. We review the basic algorithmic ingredients of C2-Ray before describing the changes implemented, which include a treatment of the full on the spot (OTS) approximation, secondary ionization, and multi-frequency photo-ionization and heating. We performed a series of tests against equilibrium solutions from CLOUDY as well as comparisons to the hydrogen only solutions by C2-Ray in the extensive code comparison in Iliev et al. (2006). We show that the full, coupled OTS approximation is more accurate than the simplified, uncoupled one. We find that also with helium and a multi-frequency set up, long timesteps (up to ~10% of the recombination time) still give accurate results for the ionization fractions. On the other hand, accurate results for the temperature set strong constrains on the timestep. The details of these constraints depend however on the optical depth of the cells. We use the new version of the code to confirm that the assumption made in many reionization simulations, namely that helium is singly ionized everywhere were hydrogen is, is indeed valid when the sources have stellar-like spectra. | [
"Physics Archive->astro-ph->astro-ph.CO"
] | "2012-01-03T10:35:30Z" |
2308.05025 | Evolution of Entropy with Cosmic Time | Understanding the evolution of entropy in the universe is a fundamental aspect of cosmology. This paper investigates the evolution of entropy in a spatially flat $K=0$ universe, focusing on the contributions of matter, radiation, and dark energy components. The study derives the rate of change of entropy with respect to cosmic time, taking into account the scaling relations of energy densities and temperatures for different components. The analysis reveals the dominance of radiation entropy at early times, transitioning to matter dominance as the universe expands. The constant contribution of dark energy entropy throughout cosmic time is also considered. The paper acknowledges the limitations of the simplified model and the omission of entropy generation processes, emphasizing the importance of future research to incorporate these aspects. The results highlight the complex interplay between different components and provide insights into the dynamics of entropy in the expanding universe. This study lays the foundation for further investigations into entropy evolution, urging the consideration of more comprehensive models and numerical techniques to achieve a deeper understanding of the universe's thermodynamic behavior. | [
"Physics Archive->gr-qc"
] | "2023-08-09T15:44:38Z" |
2211.16146 | New upper bound for the connective constant for square-lattice self-avoiding walks | By modifying the automaton used by P{\"o}nitz and Tittman [4], and considering loops of length up to 26, we obtain 2.662343 as an upper bound for the connective constant in the lattice Z 2 . | [
"Mathematics Archive->math.CO"
] | "2022-11-29T12:20:16Z" |
math/0407412 | A Pieri-type formula for the K-theory of a flag manifold | We derive explicit Pieri-type multiplication formulas in the Grothendieck ring of a flag variety. These expand the product of an arbitrary Schubert class and a special Schubert class in the basis of Schubert classes. These special Schubert classes are indexed by a cycle which has either the form (k-p+1,k-p+2,...,k+1) or the form (k+p,k+p-1,...,k), and are pulled back from a Grassmannian projection. Our formulas are in terms of certain labeled chains in the k-Bruhat order on the symmetric group and are combinatorial in that they involve no cancellations. We also show that the multiplicities in the Pieri formula are naturally certain binomial coefficients. | [
"Mathematics Archive->math.AG",
"Mathematics Archive->math.CO"
] | "2004-07-23T21:31:33Z" |
quant-ph/0404037 | Minimum Renyi and Wehrl entropies at the output of bosonic channels | The minimum Renyi and Wehrl output entropies are found for bosonic channels in which the signal photons are either randomly displaced by a Gaussian distribution (classical-noise channel), or in which they are coupled to a thermal environment through lossy propagation (thermal-noise channel). It is shown that the Renyi output entropies of integer orders z>1 and the output Wehrl entropy are minimized when the channel input is a coherent state. | [
"Physics Archive->quant-ph"
] | "2004-04-06T08:33:59Z" |
math/0104126 | On Positive Sasakian Geometry | A Sasakian structure on a manifold is called {\it positive} if its basic first Chern class can be represented by a positive (1,1)-form with respect to its transverse holomorphic CR-structure. We prove a theorem that says that every positive Sasakian structure can be deformed to a Sasakian structure whose metric has positive Ricci curvature. This allows us by example to give a completely independent proof of a result of Sha and Yang [SY] that for every positive integer k the k-fold connected sum of $S^2\times S^3$ admits metrics of positive Ricci curvature. | [
"Mathematics Archive->math.DG"
] | "2001-04-11T18:15:31Z" |
0811.3668 | On the conformally coupled scalar field quantum cosmology | We propose a new initial condition for the homogeneous and isotropic quantum cosmology, where the source of the gravitational field is a conformally coupled scalar field, and the maximally symmetric hypersurfaces have positive curvature. After solving corresponding Wheeler-DeWitt equation, we obtain exact solutions in both classical and quantum levels. We propose appropriate initial condition for the wave packets which results in a complete classical and quantum correspondence. These wave packets closely follow the classical trajectories and peak on them. We also quantify this correspondence using de-Broglie Bohm interpretation of quantum mechanics. Using this proposal, the quantum potential vanishes along the Bohmian paths and the classical and Bohmian trajectories coincide with each other. We show that the model contains singularities even at the quantum level. Therefore, the resulting wave packets closely follow the classical trajectories from big-bang to big-crunch. | [
"Physics Archive->gr-qc"
] | "2008-11-22T08:34:09Z" |
2210.11844 | Cox-Hawkes: doubly stochastic spatiotemporal Poisson processes | Hawkes processes are point process models that have been used to capture self-excitatory behavior in social interactions, neural activity, earthquakes and viral epidemics. They can model the occurrence of the times and locations of events. Here we develop a new class of spatiotemporal Hawkes processes that can capture both triggering and clustering behavior and we provide an efficient method for performing inference. We use a log-Gaussian Cox process (LGCP) as prior for the background rate of the Hawkes process which gives arbitrary flexibility to capture a wide range of underlying background effects (for infectious diseases these are called endemic effects). The Hawkes process and LGCP are computationally expensive due to the former having a likelihood with quadratic complexity in the number of observations and the latter involving inversion of the precision matrix which is cubic in observations. Here we propose a novel approach to perform MCMC sampling for our Hawkes process with LGCP background, using pre-trained Gaussian Process generators which provide direct and cheap access to samples during inference. We show the efficacy and flexibility of our approach in experiments on simulated data and use our methods to uncover the trends in a dataset of reported crimes in the US. | [
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | "2022-10-21T09:47:34Z" |
2105.08808 | Correlated Adversarial Joint Discrepancy Adaptation Network | Domain adaptation aims to mitigate the domain shift problem when transferring knowledge from one domain into another similar but different domain. However, most existing works rely on extracting marginal features without considering class labels. Moreover, some methods name their model as so-called unsupervised domain adaptation while tuning the parameters using the target domain label. To address these issues, we propose a novel approach called correlated adversarial joint discrepancy adaptation network (CAJNet), which minimizes the joint discrepancy of two domains and achieves competitive performance with tuning parameters using the correlated label. By training the joint features, we can align the marginal and conditional distributions between the two domains. In addition, we introduce a probability-based top-$\mathcal{K}$ correlated label ($\mathcal{K}$-label), which is a powerful indicator of the target domain and effective metric to tune parameters to aid predictions. Extensive experiments on benchmark datasets demonstrate significant improvements in classification accuracy over the state of the art. | [
"Computer Science Archive->cs.CV"
] | "2021-05-18T19:52:08Z" |
2012.08371 | Limiting laws and consistent estimation criteria for fixed and diverging number of spiked eigenvalues | In this paper, we study limiting laws and consistent estimation criteria for the extreme eigenvalues in a spiked covariance model of dimension $p$. Firstly, for fixed $p$, we propose a generalized estimation criterion that can consistently estimate, $k$, the number of spiked eigenvalues. Compared with the existing literature, we show that consistency can be achieved under weaker conditions on the penalty term. Next, allowing both $p$ and $k$ to diverge, we derive limiting distributions of the spiked sample eigenvalues using random matrix theory techniques. Notably, our results do not require the spiked eigenvalues to be uniformly bounded from above or tending to infinity, as have been assumed in the existing literature. Based on the above derived results, we formulate a generalized estimation criterion and show that it can consistently estimate $k$, while $k$ can be fixed or grow at an order of $k=o(n^{1/3})$. We further show that the results in our work continue to hold under a general population distribution without assuming normality. The efficacy of the proposed estimation criteria is illustrated through comparative simulation studies. | [
"Mathematics Archive->math.ST",
"Statistics Archive->stat.ME",
"Statistics Archive->stat.TH"
] | "2020-12-15T15:36:03Z" |
hep-ph/9610288 | Quark transverse momentum in hard scattering processes | The role of transverse momentum of quarks in semi-inclusive leptoproduction will be discussed. It involves generalized distribution and fragmentation functions which depend on both the longitudinal lightcone momentum fraction of the quarks and on the transverse momentum. Constraints on these functions and relations between them arise as a consequence of the QCD equation of motion for the quark fields, Lorentz invariance and of C, P, and T invariance of the strong interactions. Experimentally one has access to the functions for instance in measurements of azimuthal asymmetries in hard processes. | [
"Physics Archive->hep->hep-ph"
] | "1996-10-08T14:33:57Z" |
2212.04039 | Note on the 3-dimensional lc abundance in characteristic $> 3$ | In this paper, we prove the non-vanishing and some special cases of the log abundance for lc threefold pairs over an algebraically closed field $k$ of characteristic $p > 3$. More precisely, we prove that if $(X,B)$ be a projective lc threefold pair over $k$ and $K_{X}+B$ is pseudo-effective, then $\kappa(K_{X}+B)\geq 0$, and if $K_{X}+B$ is nef and $\kappa(K_{X}+B)\geq 1$, then $K_{X}+B$ is semiample. As applications, we show that the log canonical rings of projective lc threefold pairs over $k$ are finitely generated, and the log abundance holds when the nef dimension $n(K_{X}+B)\leq 2$ or when the Albanese map $a_{X}:X\to \mathrm{Alb}(X)$ is non-trivial. Moreover, we prove that the log abundance for klt threefold pairs over $k$ implies the log abundance for lc threefold pairs over $k$. | [
"Mathematics Archive->math.AG"
] | "2022-12-08T02:26:42Z" |
1912.10624 | Algebraic Properties for Certain Form of the Members of Sequence on Generalized Modified Camassa-Holm Equation | We study the symmetry and integrability of a Generalized Modified Camassa-Holm Equation (GMCH) of the form $$u_{t}-u_{xxt}+2nu_{x}(u^2-u_{x}^2)^{n-1}(u-u_{xx})^2+(u^2-u_{x}^2)^{n}(u_{x}-u_{xxx})=0.$$ We observe that for increasing values of $n\in \mathbb{N}$, $\mathbb{N}$ denotes natural number, the above equation gives a family of equations in which nonlinearity is rapidly increasing as $n$ increases. However, this family has similar form of symmetries except the values of $n$. Interestingly the resultant second-order nonlinear ODE which is to be obtained from GMCH equation has eight dimensional symmetries. Hence the second-order nonlinear ODE is linearizable. Finally we conclude that the resultant second-order nonlinear ordinary differential equation which is obtained from the family of GMCH passes the Painlev\'e Test also it posses the similar form of leading order, resonances and truncated series solution too. | [
"Physics Archive->nlin->nlin.SI"
] | "2019-12-23T05:23:23Z" |
1904.10965 | Astrometric requirements for strong lensing time-delay cosmography | The time delay between the arrival of photons of multiple images of time variable sources can be used to constrain absolute distances in the Universe (Refsdal 1964), and in turn obtain a direct estimate of the Hubble constant and other cosmological parameters. To convert the time delay into distances, it is well known that the gravitational potential of the main deflector and the contribution of the matter along the line-of-sight need to be known to a sufficient level of precision. In this paper, we discuss a new astrometric requirement that is becoming important as time-delay cosmography improves in precision and accuracy with larger samples, and better data and modelling techniques. We derive an analytic expression for the propagation of astrometric uncertainties on the multiple image positions into the inference of the Hubble constant and derive requirements depending on image separation and relative time delay. We note that this requirement applies equally to the image position measurements and to the accuracy of the model in reproducing them. To illustrate the requirement, we discuss some example lensing configurations and highlight that, especially for time delays of order 10 days or shorter, the relative astrometric requirement is of order milli-arcseconds, setting a tight requirement on both measurements and models. With current optical infrared technology, astrometric uncertainties may be the dominant limitation for strong lensing cosmography in the small image-separation regime when high-precision time-delays become accessible. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.GA"
] | "2019-04-24T18:00:00Z" |
2204.06921 | M-center in low-energy electron irradiated 4H-SiC | We report on the low-energy electron irradiated 4H-SiC material studied by means of deep-level transient spectroscopy (DLTS) and Laplace-DLTS. Electron irradiation has introduced the following deep level defects: EH1 and EH3 previously assigned to carbon interstitial-related defects, and M-center, a metastable defect also recently assigned to carbon interstitial defects. We propose that EH1 and EH3 are identical to M1 and M3 and assign them to C_i^(= ) (h) and C_i^(0 ) (h), respectively. Moreover, we provide direct evidence that Laplace-DLTS can be used as an excellent tool to distinguish otherwise identical DLTS signals associated with S1 (VSi) and EH1 (Ci). | [
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | "2022-04-14T12:26:19Z" |
2110.08679 | An Acceleration Method Based on Deep Learning and Multilinear Feature Space | Computer vision plays a crucial role in Advanced Assistance Systems. Most computer vision systems are based on Deep Convolutional Neural Networks (deep CNN) architectures. However, the high computational resource to run a CNN algorithm is demanding. Therefore, the methods to speed up computation have become a relevant research issue. Even though several works on architecture reduction found in the literature have not yet been achieved satisfactory results for embedded real-time system applications. This paper presents an alternative approach based on the Multilinear Feature Space (MFS) method resorting to transfer learning from large CNN architectures. The proposed method uses CNNs to generate feature maps, although it does not work as complexity reduction approach. After the training process, the generated features maps are used to create vector feature space. We use this new vector space to make projections of any new sample to classify them. Our method, named AMFC, uses the transfer learning from pre-trained CNN to reduce the classification time of new sample image, with minimal accuracy loss. Our method uses the VGG-16 model as the base CNN architecture for experiments; however, the method works with any similar CNN model. Using the well-known Vehicle Image Database and the German Traffic Sign Recognition Benchmark, we compared the classification time of the original VGG-16 model with the AMFC method, and our method is, on average, 17 times faster. The fast classification time reduces the computational and memory demands in embedded applications requiring a large CNN architecture. | [
"Computer Science Archive->cs.CV"
] | "2021-10-16T23:49:12Z" |
0806.1080 | Phantom Energy Accretion onto Black Holes in Cyclic Universe | Black holes pose a serious problem in the cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by the phantom energy before turnaround before they can create any problems. In this paper, using the mechanism of the phantom accretion onto black holes, we find that black holes do not disappear before the phantom turnaround. But the remanent black holes will not cause any problems due to the Hawking evaporation. | [
"Physics Archive->hep->hep-th"
] | "2008-06-06T02:08:57Z" |
2005.01641 | A Tale of a Probe and a Parser | Measuring what linguistic information is encoded in neural models of language has become popular in NLP. Researchers approach this enterprise by training "probes" - supervised models designed to extract linguistic structure from another model's output. One such probe is the structural probe (Hewitt and Manning, 2019), designed to quantify the extent to which syntactic information is encoded in contextualised word representations. The structural probe has a novel design, unattested in the parsing literature, the precise benefit of which is not immediately obvious. To explore whether syntactic probes would do better to make use of existing techniques, we compare the structural probe to a more traditional parser with an identical lightweight parameterisation. The parser outperforms structural probe on UUAS in seven of nine analysed languages, often by a substantial amount (e.g. by 11.1 points in English). Under a second less common metric, however, there is the opposite trend - the structural probe outperforms the parser. This begs the question: which metric should we prefer? | [
"Computer Science Archive->cs.CL"
] | "2020-05-04T16:57:31Z" |
0712.4377 | Quantum Kolmogorov Complexity and the Quantum Turing Machine | The purpose of this thesis is to give a formal definition of quantum Kolmogorov complexity (QC), and rigorous mathematical proofs of its basic properties. The definition used here is similar to that by Berthiaume, van Dam, and Laplante. It defines the QC of some indeterminate-length qubit string \rho as the minimum base length of any quantum input which makes a quantum Turing machine (QTM) halt and output \rho, up to some error tolerance. First, we prove that there is a QTM which is universal in the sense of input base length. Furthermore, we show several general properties of QTMs, including a result on mutually orthogonal ``halting spaces'', and a way to transform every almost-halting input into a deterministically-halting input by adding at most a constant number of qubits. Afterwards, we apply these results to QC. In particular, we show that QC is invariant, incompressible, agrees with classical Kolmogorov complexity for classical strings, and is closely related to von Neumann entropy for ergodic quantum information sources. | [
"Physics Archive->quant-ph"
] | "2007-12-28T17:29:09Z" |
1410.2238 | Radial Migration of the Sun in the Milky Way: a Statistical Study | The determination of the birth radius of the Sun is important to understand the evolution and consequent disruption of the Sun's birth cluster in the Galaxy. Motivated by this fact, we study the motion of the Sun in the Milky Way during the last 4.6 Gyr in order to find its birth radius. We carried out orbit integrations backward in time using an analytical model of the Galaxy which includes the contribution of spiral arms and a central bar. We took into account the uncertainty in the parameters of the Milky Way potential as well as the uncertainty in the present day position and velocity of the Sun. We find that in general the Sun has not migrated from its birth place to its current position in the Galaxy (R_\odot). However, significant radial migration of the Sun is possible when: 1) The 2:1 Outer Lindblad resonance of the bar is separated from the corrotation resonance of spiral arms by a distance ~1 kpc. 2) When these two resonances are at the same Galactocentric position and further than the solar radius. In both cases the migration of the Sun is from outer regions of the Galactic disk to R_\odot, placing the Sun's birth radius at around 11 kpc. We find that in general it is unlikely that the Sun has migrated significantly from the inner regions of the Galactic disk to R_\odot. | [
"Physics Archive->astro-ph->astro-ph.GA"
] | "2014-10-08T19:59:07Z" |
0810.3108 | Two bright submillimeter galaxies in a z=4.05 proto-cluster in GOODS-North, and accurate radio-infrared photometric redshifts | We present the serendipitous discovery of z=4.05 molecular gas CO emission lines with the IRAM Plateau de Bure interferometer coincident with GN20 and GN20.2, two luminous submillimeter galaxies (SMGs) in the Great Observatories Origins Deep Survey North field (GOODS-N). These are among the most distant submillimeter-selected galaxies reliably identified through CO emission and also some of the most luminous known. In terms of CO to bolometric luminosities, stellar mass and star formation rates (SFRs), these newly discovered z>4 SMGs are similar to z~1.5-3 SMGs studied to date. These z~4 SMGs have much higher specific SFRs than typical B-band dropout Lyman break galaxies at the same redshift. The stellar mass-SFR correlation for normal galaxies does not seem to evolve much further, between z~2 and z~4. A significant z=4.05 spectroscopic redshift spike is observed in GOODS-N, and a strong spatial overdensity of B-band dropouts and IRAC selected z>3.5 galaxies appears to be centered on the GN20 and GN20.2 galaxies. This suggests a proto-cluster structure with total mass ~10^14 Msun. Using photometry at mid-IR, submm and radio wavelengths, we show that reliable photometric redshifts (Dz/(1+z)~0.1) can be derived for SMGs over 1<z<4. This new photometric redshift technique has been used to provide a first estimate of the space density of 3.5<z<6 hyper-luminous starburst galaxies, and to show that they contribute substantially to the SFR density at early epochs. Many of these high-redshift starbursts will be within reach of Herschel. We find that the radio to mid-IR flux density ratio can be used to select z>3.5 starbursts, regardless of their submm/mm emission [abridged]. | [
"Physics Archive->astro-ph"
] | "2008-10-17T09:48:04Z" |
2311.01851 | Holistic Representation Learning for Multitask Trajectory Anomaly Detection | Video anomaly detection deals with the recognition of abnormal events in videos. Apart from the visual signal, video anomaly detection has also been addressed with the use of skeleton sequences. We propose a holistic representation of skeleton trajectories to learn expected motions across segments at different times. Our approach uses multitask learning to reconstruct any continuous unobserved temporal segment of the trajectory allowing the extrapolation of past or future segments and the interpolation of in-between segments. We use an end-to-end attention-based encoder-decoder. We encode temporally occluded trajectories, jointly learn latent representations of the occluded segments, and reconstruct trajectories based on expected motions across different temporal segments. Extensive experiments on three trajectory-based video anomaly detection datasets show the advantages and effectiveness of our approach with state-of-the-art results on anomaly detection in skeleton trajectories. | [
"Computer Science Archive->cs.CV"
] | "2023-11-03T11:32:53Z" |
2002.08547 | Deep Fusion of Local and Non-Local Features for Precision Landslide Recognition | Precision mapping of landslide inventory is crucial for hazard mitigation. Most landslides generally co-exist with other confusing geological features, and the presence of such areas can only be inferred unambiguously at a large scale. In addition, local information is also important for the preservation of object boundaries. Aiming to solve this problem, this paper proposes an effective approach to fuse both local and non-local features to surmount the contextual problem. Built upon the U-Net architecture that is widely adopted in the remote sensing community, we utilize two additional modules. The first one uses dilated convolution and the corresponding atrous spatial pyramid pooling, which enlarged the receptive field without sacrificing spatial resolution or increasing memory usage. The second uses a scale attention mechanism to guide the up-sampling of features from the coarse level by a learned weight map. In implementation, the computational overhead against the original U-Net was only a few convolutional layers. Experimental evaluations revealed that the proposed method outperformed state-of-the-art general-purpose semantic segmentation approaches. Furthermore, ablation studies have shown that the two models afforded extensive enhancements in landslide-recognition performance. | [
"Computer Science Archive->cs.CV",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | "2020-02-20T03:18:59Z" |
hep-th/9812201 | String Theory and Beyond | This is the written version of a short talk given at the University of Leipzig in December 1998. It reviews some general aspects of string theory from the viewpoint of the search for an unifying theory. Here, special emphasis lies on the motivation to consider string theory not only as the leading candidate for the unification of gravity and the other fundamental forces of nature, but also as a possible step towards a new understanding of nature and its description within the framework of physical models. Without going into details, some recent developments, including duality symmetries and the appearance of $M$--theory, are reviewed. | [
"Physics Archive->hep->hep-th"
] | "1998-12-22T12:52:48Z" |
0711.2136 | The orbital and superhump periods of the deeply eclipsing dwarf nova SDSS J122740.83+513925.9 | During June 2007 the first confirmed superoutburst of the eclipsing dwarf nova SDSS J122740.83+513925.9 was observed using CCD photometry. The outburst amplitude was at least 4.7 magnitudes. The orbital period was measured as 0.06296(5) d from times of the 31 observed eclipses. Time series photometry also revealed superhumps with a period of 0.0653(3) d, thereby establishing it to be a UGSU-type system. The superhump period excess was 3.7% and the maximum peak-to-peak amplitude of the superhumps was 0.35 magnitudes. The eclipse duration declined from a maximum of 23 min at the peak of the outburst to about 12 mins towards the end. The depth of the eclipses was correlated with the beat period between the orbital and superhump periods. | [
"Physics Archive->astro-ph"
] | "2007-11-14T09:24:40Z" |
1010.6161 | High-Intensity Probes of Axion-Like Particles | With continuously increasing intensities, modern laser systems can become a valuable tool for the search for axions and axion-like particles. As conventional setups of axion searches cannot easily accommodate the usage of a high-intensity laser system, we propose a novel, purely laser-based setup in which the occurrence of a frequency shift is an observable for the axion-photon interaction. | [
"Physics Archive->hep->hep-ph"
] | "2010-10-29T09:30:01Z" |
1807.06188 | The SPIRIT Telescope Initiative: six years on | Now in its sixth year of operation, the SPIRIT initiative remains unique in Australia, as a robust web-enabled robotic telescope initiative funded for education and outreach. With multiple modes of operation catering for a variety of usage scenarios and a fully supported education program, SPIRIT provides free access to contemporary astronomical tools for students and educators in Western Australia and beyond. The technical solution itself provides an excellent model for low cost robotic telescope installations, and the education program has evolved over time to include a broad range of student experiences - from engagement activities to authentic science. This paper details the robotic telescope solution, student interface and educational philosophy, summarises achievements and lessons learned and examines the possibilities for future enhancement including spectroscopy. | [
"Physics Archive->astro-ph->astro-ph.IM"
] | "2018-07-17T02:49:54Z" |
0906.0736 | Implications of an astrophysical interpretation of PAMELA and Fermi-LAT data for future searches of a positron signal from dark matter annihilations | The recent data from PAMELA and Fermi-LAT can be interpreted as evidence of new astrophysical sources of high energy positrons. In that case, such astrophysical positrons constitute an additional background against the positrons from dark matter annihilation. In this paper, we study the effect of that background on the prospects for the detection of a positron dark matter signal in future experiments. In particular, we determine the new regions in the (mass, $\sigmav$) plane that are detectable by the AMS-02 experiment for several dark matter scenarios and different propagation models. We find that, due to the increased background, these regions feature annihilation rates that are up to a factor or three larger than those obtained for the conventional background. That is, an astrophysical interpretation of the present data by PAMELA and Fermi-LAT implies that the detection of positrons from dark matter annihilation is slightly more challenging than previously believed. | [
"Physics Archive->hep->hep-ph"
] | "2009-06-03T16:02:27Z" |
1802.03651 | Deep learning with t-exponential Bayesian kitchen sinks | Bayesian learning has been recently considered as an effective means of accounting for uncertainty in trained deep network parameters. This is of crucial importance when dealing with small or sparse training datasets. On the other hand, shallow models that compute weighted sums of their inputs, after passing them through a bank of arbitrary randomized nonlinearities, have been recently shown to enjoy good test error bounds that depend on the number of nonlinearities. Inspired from these advances, in this paper we examine novel deep network architectures, where each layer comprises a bank of arbitrary nonlinearities, linearly combined using multiple alternative sets of weights. We effect model training by means of approximate inference based on a t-divergence measure; this generalizes the Kullback-Leibler divergence in the context of the t-exponential family of distributions. We adopt the t-exponential family since it can more flexibly accommodate real-world data, that entail outliers and distributions with fat tails, compared to conventional Gaussian model assumptions. We extensively evaluate our approach using several challenging benchmarks, and provide comparative results to related state-of-the-art techniques. | [
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | "2018-02-10T21:27:02Z" |
2308.08580 | Impact of Charge on Traversable Wormhole Solutions in $f(R,T)$ Theory | This paper examines the effects of charge on traversable wormhole structure in $f(R,T)$ theory. For this purpose, we use the embedding class-I approach to build a wormhole shape function from the static spherically symmetric spacetime. The developed shape function satisfies all the required conditions and connects two asymptotically flat regions of spacetime. We consider different models of this modified theory to examine the traversable wormhole solutions through null energy condition and also check their stable state. We conclude that viable and stable wormhole solutions are obtained under the influence of charge in this gravitational theory. | [
"Physics Archive->gr-qc"
] | "2023-08-16T13:36:51Z" |
math/0701679 | Ad-Nilpotent Ideals of a Parabolic Subalgebra | We extend the results of Cellini-Papi on the characterizations of nilpotent and abelian ideals of a Borel subalgebra to parabolic subalgebras of a simple Lie algebra. These characterizations are given in terms of elements of the affine Weyl group and faces of alcoves. In the case of a parabolic subalgebra of a classical Lie algebra, we give formulas for the number of these ideals. | [
"Mathematics Archive->math.RT"
] | "2007-01-24T13:37:14Z" |
hep-lat/0512016 | Partially Quenched Chiral Perturbation Theory to NNLO | This paper summarizes the recent calculations of the masses and decay constants of the pseudoscalar mesons at the two-loop level, or NNLO, in Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications include chiral extrapolations of Lattice QCD, as well as the determination of the low-energy constants (LEC:s) of QCD. | [
"Physics Archive->hep->hep-lat"
] | "2005-12-13T13:36:34Z" |
1612.02317 | A Matrix Splitting Method for Composite Function Minimization | Composite function minimization captures a wide spectrum of applications in both computer vision and machine learning. It includes bound constrained optimization and cardinality regularized optimization as special cases. This paper proposes and analyzes a new Matrix Splitting Method (MSM) for minimizing composite functions. It can be viewed as a generalization of the classical Gauss-Seidel method and the Successive Over-Relaxation method for solving linear systems in the literature. Incorporating a new Gaussian elimination procedure, the matrix splitting method achieves state-of-the-art performance. For convex problems, we establish the global convergence, convergence rate, and iteration complexity of MSM, while for non-convex problems, we prove its global convergence. Finally, we validate the performance of our matrix splitting method on two particular applications: nonnegative matrix factorization and cardinality regularized sparse coding. Extensive experiments show that our method outperforms existing composite function minimization techniques in term of both efficiency and efficacy. | [
"Mathematics Archive->math.OC"
] | "2016-12-07T16:29:18Z" |
astro-ph/0512292 | Gas Flow Across Gaps in Protoplanetary Disks | We analyze the gas accretion flow through a planet-produced gap in a protoplanetary disk. We adopt the alpha disk model and ignore effects of planetary migration. We develop a semi-analytic, one-dimensional model that accounts for the effects of the planet as a mass sink and also carry out two-dimensional hydrodynamical simulations of a planet embedded in a disk. The predictions of the mass flow rate through the gap based on the semi-analytic model generally agree with the hydrodynamical simulations at the 25% level. Through these models, we are able to explore steady state disk structures and over large spatial ranges. The presence of an accreting Jupiter-mass planet significantly lowers the density of the disk within a region of several times the planet's orbital radius. The mass flow rate across the gap (and onto the central star) is typically 10% to 25% of the mass accretion rate outside the orbit of the planet, for planet-to-star mass ratios that range from 5e-5 to 1e-3. | [
"Physics Archive->astro-ph"
] | "2005-12-12T14:46:55Z" |
physics/9807018 | On the determination of probability density functions by using Neural Networks | It is well known that the output of a Neural Network trained to disentangle between two classes has a probabilistic interpretation in terms of the a-posteriori Bayesian probability, provided that a unary representation is taken for the output patterns. This fact is used to make Neural Networks approximate probability density functions from examples in an unbinned way, giving a better performace than ``standard binned procedures''. In addition, the mapped p.d.f. has an analytical expression. | [
"Physics Archive->physics->physics.data-an"
] | "1998-07-14T16:00:59Z" |
astro-ph/0604391 | Comparing Dynamical and Stellar Population Mass-to-Light Ratio Estimates | We investigate the mass-to-light ratios of stellar populations as predicted by stellar population synthesis codes and compare those to dynamical/gravitational measurements. In Bell & de Jong (2001) we showed that population synthesis models predict a tight relation between the color and mass-to-light ratio of a stellar population. The normalization of this relation depends critically on the shape of the stellar IMF at the low-mass end. These faint stars contribute significantly to the mass, but insignificantly to the luminosity and color of a stellar system. In Bell & de Jong (2001) we used rotation curves to normalize the relation, but rotation curves provide only an upper limit to the stellar masses in a system. Here we compare stellar and dynamical masses for a range of stellar systems in order to constrain the mass normalization of stellar population models. We find that the normalization of Bell & de Jong (2001) should be lowered by about 0.05-0.1 dex in M/L. This is consistent with a Kroupa (2001), Chabrier (2003) or a Kennicutt (1983) IMF, but does not leave much room for other unseen components. | [
"Physics Archive->astro-ph"
] | "2006-04-19T13:08:48Z" |
1102.5572 | Is Dark Energy a Cosmic Casimir Effect? | Unknown short-distance effects cancel the quartic divergence of the zero-point energies. If this renormalization took effect in the early universe after the last phase transition and applied only to modes whose wavelengths (over 2 pi) were shorter than the Hubble length 1/H at that time, then the zero-point energies of the modes of longer wavelengths can approximately account for the present value of the dark-energy density. The model makes two predictions. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->hep->hep-ph"
] | "2011-02-28T02:19:59Z" |
2304.11935 | Prediction of the collisions of meteoroids originating in comet 21P/Giacobini-Zinner with the Mercury, Venus, and Mars | After the prediction of meteor showers in the Earth's atmosphere caused by the particles originating in the nucleus of comet 21P/Giacobini-Zinner, we went on with the prediction of showers on the other three terrestrial planets. Based on our modeling of theoretical stream of the parent comet, we predicted several related meteorite (on Mercury) or meteor (on Venus and Mars) showers. There occurred the filaments, in the stream, with the particles coming to each planet from a similar direction. We found that this is a consequence of the specific distribution of argument of perihelion (peaked close to the value of $180^{\circ}$) and longitude of ascending node of the stream, and that the particles collide with each planet in an arc of their orbits being close to perihelion. | [
"Physics Archive->astro-ph->astro-ph.EP"
] | "2023-04-24T09:18:15Z" |
1601.05726 | Comet formation in collapsing pebble clouds. What cometary bulk density implies for the cloud mass and dust-to-ice ratio | Comets are remnants of the icy planetesimals that formed beyond the ice line in the Solar Nebula. Growing from micrometre-sized dust and ice particles to km-sized objects is, however, difficult because of growth barriers and time scale constraints. The gravitational collapse of pebble clouds that formed through the streaming instability may provide a suitable mechanism for comet formation. We study the collisional compression of cm-sized porous ice/dust-mixed pebbles in collapsing pebble clouds. For this, we developed a collision model for pebbles consisting of a mixture of ice and dust, characterised by their dust-to-ice mass ratio. Using the final compression of the pebbles, we constrain combinations of initial cloud mass, initial pepple porosity, and dust-to-ice ratio that lead to cometesimals which are consistent with observed bulk properties of cometary nuclei. We find that observed high porosity and low density of ~0.5 g/cc of comet nuclei can only be explained if comets formed in clouds with mass approximately M>1e18 g. Lower mass clouds would only work if the pebbles were initially very compact. Furthermore, the dust-to-ice ratio must be in the range of between 3 and 9 to match the observed bulk properties of comet nuclei. (abridged version) | [
"Physics Archive->astro-ph->astro-ph.EP"
] | "2016-01-21T17:54:31Z" |
hep-th/9505173 | Local BRST cohomology in Einstein--Yang--Mills theory | We analyse in detail the local BRST cohomology in Einstein-Yang-Mills theory using the antifield formalism. We do not restrict the Lagrangian to be the sum of the standard Hilbert and Yang-Mills Lagrangians, but allow for more general diffeomorphism and gauge invariant actions. The analysis is carried out in all spacetime dimensions larger than 2 and for all ghost numbers. This covers the classification of all candidate anomalies, of all consistent deformations of the action, as well as the computation of the (equivariant) characteristic cohomology, i.e. the cohomology of the spacetime exterior derivative in the space of (gauge invariant) local differential forms modulo forms that vanish on-shell. We show in particular that for a semi-simple Yang-Mills gauge group the antifield dependence can be entirely removed both from the consistent deformations of the Lagrangian and from the candidate anomalies. Thus, the allowed deformations of the action necessarily preserve the gauge structure, while the only candidate anomalies are those provided by previous works not dealing with antifields, and by ``topological" candidate anomalies which are present only in special spacetime dimensions (6,9,10,13,...). This result no longer holds in presence of abelian factors where new candidate anomalies and deformations of the action can be constructed out of the conserved Noether currents (if any). The Noether currents themselves are shown to be covariantizable, with a few exceptions discussed as well. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "1995-05-29T12:18:21Z" |
astro-ph/0202387 | Efficient acceleration and radiation in Poynting flux powered GRB outflows | We investigate the effects of magnetic energy release by local magnetic dissipation processes in Poynting flux-powered GRBs. For typical GRB parameters (energy and baryon loading) the dissipation takes place mainly outside the photosphere, producing non-thermal radiation. This process converts the total burst energy into prompt radiation at an efficiency of 10-50%. At the same time the dissipation has the effect of accelerating the flow to a large Lorentz factor. For higher baryon loading, the dissipation takes place mostly inside the photosphere, the efficiency of conversion of magnetic energy into radiation is lower, and an X-ray flash results instead of a GRB. We demonstrate these effects with numerical one-dimensional steady relativistic MHD calculations. | [
"Physics Archive->astro-ph"
] | "2002-02-21T08:52:18Z" |
1306.4349 | The center of mass energy of two colliding particles in the STU black holes | In this paper we consider collision of two particle near the STU black hole and calculate center of mass energy. In the case of uncharged black hole we find that the maximum energy obtained near the black hole horizon which similarly happen for charged black hole. We verify that the black hole charge may be decreased or increased the center of mass energy near the black hole horizon. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "2013-06-15T08:10:00Z" |
hep-ph/0301182 | Electroproduction of vector mesons - factorization of end-point contributions | The end-point contributions in the quark longitudinal momentum fraction of the virtual photon ($\gamma^*$) to vector meson ($V$) impact factor to the diffractive electroproduction amplitude can be factorized in terms of a generalized parton evolution of the target parton distribution. The result is used to model the helicity amplitudes $\gamma^* p \to V p$ in terms of small $x$ generalized parton distributions. | [
"Physics Archive->hep->hep-ph"
] | "2003-01-21T17:45:31Z" |
0707.3222 | When is g_{tt} g_{rr} = -1? | The Schwarzschild metric, its Reissner-Nordstrom-de Sitter generalizations to higher dimensions, and some further generalizations all share the feature that g_{tt} g_{rr}=-1 in Schwarzschild-like coordinates. In this pedagogical note we trace this feature to the condition that the Ricci tensor (and stress-energy tensor in a solution to Einstein's equation) has vanishing radial null-null component, i.e. is proportional to the metric in the t-r subspace. We also show this condition holds if and only if the area-radius coordinate is an affine parameter on the radial null geodesics. | [
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | "2007-07-21T18:28:42Z" |
1301.6147 | A Search for Exozodiacal Clouds with Kepler | Planets embedded within dust disks may drive the formation of large scale clumpy dust structures by trapping dust into resonant orbits. Detection and subsequent modeling of the dust structures would help constrain the mass and orbit of the planet and the disk architecture, give clues to the history of the planetary system, and provide a statistical estimate of disk asymmetry for future exoEarth-imaging missions. Here we present the first search for these resonant structures in the inner regions of planetary systems by analyzing the light curves of hot Jupiter planetary candidates identified by the Kepler mission. We detect only one candidate disk structure associated with KOI 838.01 at the 3-sigma confidence level, but subsequent radial velocity measurements reveal that KOI 838.01 is a grazing eclipsing binary and the candidate disk structure is a false positive. Using our null result, we place an upper limit on the frequency of dense exozodi structures created by hot Jupiters. We find that at the 90% confidence level, less than 21% of Kepler hot Jupiters create resonant dust clumps that lead and trail the planet by ~90 degrees with optical depths >~5*10^-6, which corresponds to the resonant structure expected for a lone hot Jupiter perturbing a dynamically cold dust disk 50 times as dense as the zodiacal cloud. | [
"Physics Archive->astro-ph->astro-ph.EP",
"Physics Archive->astro-ph->astro-ph.SR"
] | "2013-01-25T20:01:44Z" |
1203.4362 | Nonleptonic $B \to D^{(*)}D_{sJ}^{(*)}$ decays and the nature of the orbitally excited charmed-strange mesons | The Belle Collaboration has recently reported a study of the decays $B \to D_{s1}(2536)^{+}\bar{D}^{(\ast)}$ and has given also estimates of relevant ratios between branching fractions of decays $B \to D^{(\ast)}D_{sJ}^{(\ast)}$ providing important information to check the structure of the $D_{s0}^{\ast}(2317)$, $D_{s1}(2460)$ and $D_{s1}(2536)$ mesons. The disagreement between experimental data and Heavy Quark Symmetry has been used as an indication that $D_{s0}^{\ast}(2317)$ and $D_{s1}(2460)$ mesons could have a more complex structure than the canonical $c\bar{s}$ one. We analyze these ratios within the framework of a constituent quark model, which allows us to incorporate the effects given by finite $c$-quark mass corrections. Our findings are that while the $D_{s1}(2460)$ meson could have a sizable non-$q\bar{q}$ component, the $D_{s0}^{\ast}(2317)$ and $D_{s1}(2536)$ mesons seem to be well described by a pure $q\bar{q}$ structure. | [
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | "2012-03-20T09:58:21Z" |
dg-ga/9506012 | Einstein Metrics on Complex Surfaces | We consider compact complex surfaces with Hermitian metrics which are Einstein but not Kaehler. It is shown that the manifold must be CP2 blown up at 1,2, or 3 points, and the isometry group of the metric must contain a 2-torus. Thus the Page metric on CP2#(-CP2) is almost the only metric of this type. | [
"Mathematics Archive->math.DG"
] | "1995-06-29T16:48:19Z" |
1810.13089 | Quantum coherence control at near 1000 K | Quantum coherence control usually requires extremely low temperature environments. Even for spins in diamond, a remarkable exception, the coherence signal is lost as temperature approaches 700 K. Here we demonstrate quantum coherence control of the electron spins of nitrogen-vacancy centers in nanodiamonds at temperatures near 1000 K. The scheme is based on initialization and readout of the spins at room temperature and control at high temperature, which is enabled by pulse laser heating and rapid diffusion cooling of nanodiamonds on amorphous carbon films. Using high-temperature spin control, we observe the magnetic phase transition of a single nickel nanoparticle at about 615 K. This work enables nano-thermometry and nano-magnetometry in the high-temperature regime. | [
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->quant-ph"
] | "2018-10-31T03:20:52Z" |
2101.04823 | A reusable pipeline for large-scale fiber segmentation on unidirectional fiber beds using fully convolutional neural networks | Fiber-reinforced ceramic-matrix composites are advanced materials resistant to high temperatures, with application to aerospace engineering. Their analysis depends on the detection of embedded fibers, with semi-supervised techniques usually employed to separate fibers within the fiber beds. Here we present an open computational pipeline to detect fibers in ex-situ X-ray computed tomography fiber beds. To separate the fibers in these samples, we tested four different architectures of fully convolutional neural networks. When comparing our neural network approach to a semi-supervised one, we obtained Dice and Matthews coefficients greater than $92.28 \pm 9.65\%$, reaching up to $98.42 \pm 0.03 \%$, showing that the network results are close to the human-supervised ones in these fiber beds, in some cases separating fibers that human-curated algorithms could not find. The software we generated in this project is open source, released under a permissive license, and can be freely adapted and re-used in other domains. All data and instructions on how to download and use it are also available. | [
"Computer Science Archive->cs.CV",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | "2021-01-13T00:58:29Z" |
2303.13292 | On the pebbling numbers of some snarks | Graph pebbling is a game played on graphs with pebbles on their vertices. A pebbling move removes two pebbles from one vertex and places one pebble on an adjacent vertex. The pebbling number $\pi(G)$ is the smallest $t$ so that from any initial configuration of $t$ pebbles it is possible, after a sequence of pebbling moves, to place a pebble on any given target vertex. In this paper, we provide the first results on the pebbling numbers of snarks. | [
"Mathematics Archive->math.CO"
] | "2023-03-23T14:19:16Z" |
1803.04838 | Thermodynamic dislocation theory: Bauschinger effect | The thermodynamic dislocation theory developed for non-uniform plastic deformations is used here to simulate the stress-strain curves for crystals subjected to anti-plane shear-controlled load reversal. We show that the presence of the positive back stress during the load reversal reduces the magnitude of shear stress required to pull excess dislocations back to the center of the specimen. There, the excess dislocations of opposite signs meet and annihilate each other leading to the Bauschinger effect. | [
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->cond-mat->cond-mat.soft"
] | "2018-03-12T09:27:24Z" |
1408.3585 | A Bayesian blind survey for cold molecular gas in the Universe | A new Bayesian method for performing an image domain search for line-emitting galaxies is presented. The method uses both spatial and spectral information to robustly determine the source properties, employing either simple Gaussian, or other physically motivated models whilst using the evidence to determine the probability that the source is real. In this paper, we describe the method, and its application to both a simulated data set, and a blind survey for cold molecular gas using observations of the Hubble Deep Field North taken with the Plateau de Bure Interferometer. We make a total of 6 robust detections in the survey, 5 of which have counterparts in other observing bands. We identify the most secure detections found in a previous investigation, while finding one new probable line source with an optical ID not seen in the previous analysis. This study acts as a pilot application of Bayesian statistics to future searches to be carried out both for low-$J$ CO transitions of high redshift galaxies using the JVLA, and at millimeter wavelengths with ALMA, enabling the inference of robust scientific conclusions about the history of the molecular gas properties of star-forming galaxies in the Universe through cosmic time. | [
"Physics Archive->astro-ph->astro-ph.GA",
"Physics Archive->astro-ph->astro-ph.IM"
] | "2014-08-15T16:53:29Z" |
1907.08051 | Self-supervised Training of Proposal-based Segmentation via Background Prediction | While supervised object detection methods achieve impressive accuracy, they generalize poorly to images whose appearance significantly differs from the data they have been trained on. To address this in scenarios where annotating data is prohibitively expensive, we introduce a self-supervised approach to object detection and segmentation, able to work with monocular images captured with a moving camera. At the heart of our approach lies the observation that segmentation and background reconstruction are linked tasks, and the idea that, because we observe a structured scene, background regions can be re-synthesized from their surroundings, whereas regions depicting the object cannot. We therefore encode this intuition as a self-supervised loss function that we exploit to train a proposal-based segmentation network. To account for the discrete nature of object proposals, we develop a Monte Carlo-based training strategy that allows us to explore the large space of object proposals. Our experiments demonstrate that our approach yields accurate detections and segmentations in images that visually depart from those of standard benchmarks, outperforming existing self-supervised methods and approaching weakly supervised ones that exploit large annotated datasets. | [
"Computer Science Archive->cs.CV"
] | "2019-07-18T13:52:06Z" |
hep-lat/0111035 | Analytic progress on exact lattice chiral symmetry | Theoretical issues of exact chiral symmetry on the lattice are discussed and related recent works are reviewed. For chiral theories, the construction with exact gauge invariance is reconsidered from the point of view of domain wall fermion. The issue in the construction of electroweak theory is also discussed. For vector-like theories, we discuss unitarity (positivity), Hamiltonian approach, and several generalizations of the Ginsparg-Wilson relation (algebraic and odd-dimensional). | [
"Physics Archive->hep->hep-lat"
] | "2001-11-21T01:48:24Z" |
1212.4619 | Emergent Nesting of the Fermi Surface from Local-Moment Description of Iron-Pnictide High-Tc Superconductors | We uncover the low-energy spectrum of a t-J model for electrons on a square lattice of spin-1 iron atoms with 3dxz and 3dyz orbital character by applying Schwinger-boson-slave-fermion mean-field theory and by exact diagonalization of one hole roaming over a 4 x 4 x 2 lattice. Hopping matrix elements are set to produce hole bands centered at zero two-dimensional (2D) momentum in the free-electron limit. Holes can propagate coherently in the t-J model below a threshold Hund coupling when long-range antiferromagnetic order across the d+ = 3d(x+iy)z and d- = 3d(x-iy)z orbitals is established by magnetic frustration that is off-diagonal in the orbital indices. This leads to two hole-pocket Fermi surfaces centered at zero 2D momentum. Proximity to a commensurate spin-density wave (cSDW) that exists above the threshold Hund coupling results in emergent Fermi surface pockets about cSDW momenta at a quantum critical point (QCP). This motivates the introduction of a new Gutzwiller wavefunction for a cSDW metal state. Study of the spin-fluctuation spectrum at cSDW momenta indicates that the dispersion of the nested band of one-particle states that emerges is electron-type. Increasing Hund coupling past the QCP can push the hole-pocket Fermi surfaces centered at zero 2D momentum below the Fermi energy level, in agreement with recent determinations of the electronic structure of mono-layer iron-selenide superconductors. | [
"Physics Archive->cond-mat->cond-mat.supr-con"
] | "2012-12-19T10:32:22Z" |
1910.14384 | Pomsets with Boxes: Protection, Separation, and Locality in Concurrent Kleene Algebra | Concurrent Kleene Algebra is an elegant tool for equational reasoning about concurrent programs. An important feature of concurrent programs that is missing from CKA is the ability to restrict legal interleavings. To remedy this we extend the standard model of CKA, namely pomsets, with a new feature, called boxes, which can specify that part of the system is protected from outside interference. We study the algebraic properties of this new model. Another drawback of CKA is that the language used for expressing properties of programs is the same as that which is used to express programs themselves. This is often too restrictive for practical purposes. We provide a logic, 'pomset logic', that is an assertion language for specifying such properties, and which is interpreted on pomsets with boxes. In contrast with other approaches, this logic is not state-based, but rather characterizes the runtime behaviour of a program. We develop the basic metatheory for the relationship between pomset logic and CKA, including frame rules to support local reasoning, and illustrate this relationship with simple examples. | [
"Computer Science Archive->cs.LO"
] | "2019-10-31T11:30:48Z" |
hep-ph/0504274 | Possible energy-dependence of Theta_13 in neutrino oscillations | A simple three-flavor neutrino-oscillation model is discussed which has both nonzero mass differences and timelike Fermi-point splittings, together with a combined bi-maximal and trimaximal mixing pattern. One possible consequence would be new effects in \nu_{\mu} \to \nu_{e} oscillations, characterized by an energy-dependent effective mixing angle \Theta_{13}. Future experiments such as T2K and NOvA, and perhaps even the current MINOS experiment, could look for these effects. | [
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | "2005-04-28T20:57:54Z" |
2103.15105 | Single Object Tracking through a Fast and Effective Single-Multiple Model Convolutional Neural Network | Object tracking becomes critical especially when similar objects are present in the same area. Recent state-of-the-art (SOTA) approaches are proposed based on taking a matching network with a heavy structure to distinguish the target from other objects in the area which indeed drastically downgrades the performance of the tracker in terms of speed. Besides, several candidates are considered and processed to localize the intended object in a region of interest for each frame which is time-consuming. In this article, a special architecture is proposed based on which in contrast to the previous approaches, it is possible to identify the object location in a single shot while taking its template into account to distinguish it from the similar objects in the same area. In brief, first of all, a window containing the object with twice the target size is considered. This window is then fed into a fully convolutional neural network (CNN) to extract a region of interest (RoI) in a form of a matrix for each of the frames. In the beginning, a template of the target is also taken as the input to the CNN. Considering this RoI matrix, the next movement of the tracker is determined based on a simple and fast method. Moreover, this matrix helps to estimate the object size which is crucial when it changes over time. Despite the absence of a matching network, the presented tracker performs comparatively with the SOTA in challenging situations while having a super speed compared to them (up to $120 FPS$ on 1080ti). To investigate this claim, a comparison study is carried out on the GOT-10k dataset. Results reveal the outstanding performance of the proposed method in fulfilling the task. | [
"Computer Science Archive->cs.CV"
] | "2021-03-28T11:02:14Z" |
2208.12765 | Landau Singularities and Higher-Order Roots | Landau's work on the singularities of Feynman diagrams suggests that they can only be of three types: either poles, logarithmic divergences, or the roots of quadratic polynomials. On the other hand, many Feynman integrals exist whose singularities involve arbitrarily higher-order polynomial roots. We investigate this apparent paradox using concrete examples involving cube-roots in four dimensions and roots of a degree six polynomial in two dimensions, and suggest that these higher-order singularities can only be approached via kinematic limits of higher co-dimension than one, thus evading Landau's argument. | [
"Physics Archive->hep->hep-th"
] | "2022-08-26T16:23:28Z" |
1711.02818 | Enumeration of lozenge tilings of a hexagon with a shamrock missing on the symmetry axis | In their paper about a dual of MacMahon's classical theorem on plane partitions, Ciucu and Krattenthaler proved a closed form product formula for the tiling number of a hexagon with a "shamrock", a union of four adjacent triangles, removed in the center (Proc. Natl. Acad. Sci. USA 2013). Lai later presented a $q$-enumeration for lozenge tilings of a hexagon with a shamrock removed from the boundary (European J. Combin. 2017). It appears that the above are the only two positions of the shamrock hole that yield nice tiling enumerations. In this paper, we show that in the case of symmetric hexagons, we always have a simple product formula for the number of tilings when removing a shamrock at any position along the symmetry axis. Our result also generalizes Eisenk\"olbl's related work about lozenge tilings of a hexagon with two unit triangles missing on the symmetry axis (Electron. J. Combin. 1999). | [
"Mathematics Archive->math.CO"
] | "2017-11-08T04:00:31Z" |
1905.10799 | Path Ranking with Attention to Type Hierarchies | The objective of the knowledge base completion problem is to infer missing information from existing facts in a knowledge base. Prior work has demonstrated the effectiveness of path-ranking based methods, which solve the problem by discovering observable patterns in knowledge graphs, consisting of nodes representing entities and edges representing relations. However, these patterns either lack accuracy because they rely solely on relations or cannot easily generalize due to the direct use of specific entity information. We introduce Attentive Path Ranking, a novel path pattern representation that leverages type hierarchies of entities to both avoid ambiguity and maintain generalization. Then, we present an end-to-end trained attention-based RNN model to discover the new path patterns from data. Experiments conducted on benchmark knowledge base completion datasets WN18RR and FB15k-237 demonstrate that the proposed model outperforms existing methods on the fact prediction task by statistically significant margins of 26% and 10%, respectively. Furthermore, quantitative and qualitative analyses show that the path patterns balance between generalization and discrimination. | [
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.LG"
] | "2019-05-26T12:57:47Z" |
1912.09021 | AANet: Attribute Attention Network for Person Re-Identifications | This paper proposes Attribute Attention Network (AANet), a new architecture that integrates person attributes and attribute attention maps into a classification framework to solve the person re-identification (re-ID) problem. Many person re-ID models typically employ semantic cues such as body parts or human pose to improve the re-ID performance. Attribute information, however, is often not utilized. The proposed AANet leverages on a baseline model that uses body parts and integrates the key attribute information in an unified learning framework. The AANet consists of a global person ID task, a part detection task and a crucial attribute detection task. By estimating the class responses of individual attributes and combining them to form the attribute attention map (AAM), a very strong discriminatory representation is constructed. The proposed AANet outperforms the best state-of-the-art method arXiv:1711.09349v3 [cs.CV] using ResNet-50 by 3.36% in mAP and 3.12% in Rank-1 accuracy on DukeMTMC-reID dataset. On Market1501 dataset, AANet achieves 92.38% mAP and 95.10% Rank-1 accuracy with re-ranking, outperforming arXiv:1804.00216v1 [cs.CV], another state of the art method using ResNet-152, by 1.42% in mAP and 0.47% in Rank-1 accuracy. In addition, AANet can perform person attribute prediction (e.g., gender, hair length, clothing length etc.), and localize the attributes in the query image. | [
"Computer Science Archive->cs.CV"
] | "2019-12-19T05:19:45Z" |
1903.11396 | Multimaterial Heat Flow Verification | Multimaterial heat diffusion can be a challenging numerical problem when the material boundaries are misaligned with the numerical grid. Even when the boundaries start out aligned, they typically become misaligned through hydrodynamic motion. There are usually a number of methods for handling multimaterial cells in any given hydro code. One of the simplest methods is to replace the multimaterial cell by an average single-material cell whose heat capacity and conductivity are averages over the constituent materials. One can further refine this model by using either the arithmetic or harmonic averages, thereby providing two distinct (albeit naive) multimaterial models for the arithmetic and harmonic averages. More sophisticated models typically involve a surrogate mesh of some kind, as with the thin mesh and static condensation methods. In this paper, we perform rigorous code verification of the multiphysics hydrocode FLAG, including grid resolution studies. We employ a number of newly constructed 2D heat flow solutions that generalize the standard {\em planar sandwich} solution, and this paper offers a smorgasbord of exact solutions for heat flow verification. To perform the analyses and to produce the corresponding convergence plots, we employ the code verification tool ExactPack. | [
"Physics Archive->physics->physics.comp-ph"
] | "2019-03-25T22:14:48Z" |
cond-mat/9607097 | Stress Propagation and Arching in Static Sandpiles | We present a new approach to the modelling of stress propagation in static granular media, focussing on the conical sandpile constructed from a point source. We view the medium as consisting of cohesionless hard particles held up by static frictional forces; these are subject to microscopic indeterminacy which corresponds macroscopically to the fact that the equations of stress continuity are incomplete -- no strain variable can be defined. We propose that in general the continuity equations should be closed by means of a constitutive relation (or relations) between different components of the (mesoscopically averaged) stress tensor. The primary constitutive relation relates radial and vertical shear and normal stresses (in two dimensions, this is all one needs). We argue that the constitutive relation(s) should be local, and should encode the construction history of the pile: this history determines the organization of the grains at a mesoscopic scale, and thereby the local relationship between stresses. To the accuracy of published experiments, the pattern of stresses beneath a pile shows a scaling between piles of different heights (RSF scaling) which severely limits the form the constitutive relation can take ... | [
"Physics Archive->cond-mat"
] | "1996-07-13T12:29:03Z" |
2203.00729 | The Economics and Econometrics of Gene-Environment Interplay | Economists and social scientists have debated the relative importance of nature (one's genes) and nurture (one's environment) for decades, if not centuries. This debate can now be informed by the ready availability of genetic data in a growing number of social science datasets. This paper explores the potential uses of genetic data in economics, with a focus on estimating the interplay between nature (genes) and nurture (environment). We discuss how economists can benefit from incorporating genetic data into their analyses even when they do not have a direct interest in estimating genetic effects. We argue that gene--environment (GxE) studies can be instrumental for (i) testing economic theory, (ii) uncovering economic or behavioral mechanisms, and (iii) analyzing treatment effect heterogeneity, thereby improving the understanding of how (policy) interventions affect population subgroups. We introduce the reader to essential genetic terminology, develop a conceptual economic model to interpret gene-environment interplay, and provide practical guidance to empirical researchers. | [
"Economics Archive->econ.GN",
"Quantitative Finance Archive->q-fin.EC"
] | "2022-03-01T20:33:29Z" |
cond-mat/0612293 | Spin-orbit induced spin-qubit control in nanowires | We elaborate on a number of issues concerning our recent proposal for spin-qubit manipulation in nanowires using the spin-orbit coupling. We discuss the experimental status and describe in further detail the scheme for single-qubit rotations. We present a derivation of the effective two-qubit coupling which can be extended to higher orders in the Coulomb interaction. The analytic expression for the coupling strength is shown to agree with numerics. | [
"Physics Archive->cond-mat->cond-mat.mes-hall",
"Physics Archive->quant-ph"
] | "2006-12-12T15:53:52Z" |
0705.1553 | Effect of Orbital Angular Momentum on Valence-Quark Helicity Distributions | We study the quark helicity distributions at large x in perturbative QCD, taking into account contributions from the valence Fock states of the nucleon which have nonzero orbital angular momentum. These states are necessary to have a nonzero anomalous magnetic moment. We find that the quark orbital angular momentum contributes a large logarithm to the negative helicity quark distributions in addition to its power behavior, scaling as (1-x)^5\log^2(1-x) in the limit of x\to 1. Our analysis shows that the ratio of the polarized over unpolarized down quark distributions, \Delta d/d, will still approach 1 in this limit. By comparing with the experimental data, we find that this ratio should cross zero at x\approx 0.75. | [
"Physics Archive->hep->hep-ph"
] | "2007-05-10T21:56:43Z" |
cond-mat/0604133 | A note on confined diffusion | The random motion of a Brownian particle confined in some finite domain is considered. Quite generally, the relevant statistical properties involve infinite series, whose coefficients are related to the eigenvalues of the diffusion operator. Unfortunately, the latter depend on space dimensionality and on the particular shape of the domain, and an analytical expression is in most circumstances not available. In this article, it is shown that the series may in some circumstances sum up exactly. Explicit calculations are performed for 2D diffusion restricted to a circular domain and 3D diffusion inside a sphere. In both cases, the short-time behaviour of the mean square displacement is obtained. | [
"Physics Archive->cond-mat->cond-mat.soft",
"Physics Archive->cond-mat->cond-mat.stat-mech"
] | "2006-04-05T13:19:23Z" |
hep-th/0312260 | Non-Linear Field Equation from Boundary State Formalism | Boundary interactions of closed-string with open-strings are examined intended to provide a constructive formulation of boundary string field theory. As an illustration, we consider the BPS $D$-brane of the type II superstring in a constant NS-NS two-form background, and study the boundary interaction with arbitrary configurations of gauge field on the brane. The boundary interaction is presented, within the world-sheet cut-off theories, as an off-shell boundary state in the closed-string Hilbert space. It is regarded as a closed-string theoretical counterpart of the Wilson loop in the world-volume gauge theory. We show that the action of the closed-string BRST operator on the boundary state is translated into the non-linear BRST transformation of the open-string fields on the world-volume. In particular, the BRST invariance condition at the $\alpha'$-order becomes the non-linear equation of motion for the non-commutative gauge theory. The action of the closed-string BRST operator on the boundary state is also shown to be identified with the beta functions of the world-sheet renormalization group flow. | [
"Physics Archive->hep->hep-th"
] | "2003-12-22T08:29:09Z" |
1403.1561 | Big-bang nucleosynthesis through bound-state effects with a long-lived slepton in the NMSSM | We show that the Li problems can be solved in the next-to-minimal supersymmetric standard model where the slepton as the next-to-lightest SUSY particle is very long-lived. Such a long-lived slepton induces exotic nuclear reactions in big-bang nucleosynthesis, and destroys and produces the $^7$Li and $^6$Li nuclei via bound state formation. We study cases where the lightest SUSY particle is singlino-like neutralino and bino-like neutralino to present allowed regions in the parameter space which is consistent with the observations on the dark matter and the Higgs mass. | [
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->hep->hep-ph"
] | "2014-03-06T20:22:33Z" |
gr-qc/9409011 | Lifetimes of spherically symmetric closed universes | It is proven that any spherically symmetric spacetime that possesses a compact Cauchy surface $\Sigma$ and that satisfies the dominant-energy and non-negative-pressures conditions must have a finite lifetime in the sense that all timelike curves in such a spacetime must have a length no greater than $10 \max_\Sigma(2m)$, where $m$ is the mass associated with the spheres of symmetry. This result gives a complete resolution, in the spherically symmetric case, of one version of the closed-universe recollapse conjecture (though it is likely that a slightly better bound can be established). This bound has the desirable properties of being computable from the (spherically symmetric) initial data for the spacetime and having a very simple form. In fact, its form is the same as was established, using a different method, for the spherically symmetric massless scalar field spacetimes, thereby proving a conjecture offered in that work. Prospects for generalizing these results beyond the spherically symmetric case are discussed. | [
"Physics Archive->gr-qc"
] | "1994-09-06T21:04:42Z" |
2311.10492 | A Relay System for Semantic Image Transmission based on Shared Feature Extraction and Hyperprior Entropy Compression | Nowadays, the need for high-quality image reconstruction and restoration is more and more urgent. However, most image transmission systems may suffer from image quality degradation or transmission interruption in the face of interference such as channel noise and link fading. To solve this problem, a relay communication network for semantic image transmission based on shared feature extraction and hyperprior entropy compression (HEC) is proposed, where the shared feature extraction technology based on Pearson correlation is proposed to eliminate partial shared feature of extracted semantic latent feature. In addition, the HEC technology is used to resist the effect of channel noise and link fading and carried out respectively at the source node and the relay node. Experimental results demonstrate that compared with other recent research methods, the proposed system has lower transmission overhead and higher semantic image transmission performance. Particularly, under the same conditions, the multi-scale structural similarity (MS-SSIM) of this system is superior to the comparison method by approximately 0.2. | [
"Computer Science Archive->cs.CV"
] | "2023-11-17T12:45:30Z" |
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