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null | {
"abstract": " Binary mixtures of dry grains avalanching down a slope are experimentally\nstudied in order to determine the interaction among coarse and fine grains and\ntheir effect on the deposit morphology. The distance travelled by the massive\nfront of the avalanche over the horizontal plane of deposition area is measured\nas a function of mass content of fine particles in the mixture, grain-size\nratio, and flume tilt. A sudden transition of the runout is detected at a\ncritical content of fine particles, with a dependence on the grain-size ratio\nand flume tilt. This transition is explained as two simultaneous avalanches in\ndifferent flowing regimes (a viscous-like one and an inertial one) competing\nagainst each other and provoking a full segregation and a split-off of the\ndeposit into two well-defined, separated deposits. The formation of the distal\ndeposit, in turn, depends on a critical amount of coarse particles. This allows\nthe condensation of the pure coarse deposit around a small, initial seed\ncluster, which grows rapidly by braking and capturing subsequent colliding\ncoarse particles. For different grain-size ratios and keeping a constant total\nmass, the change in the amount of fines needed for the transition to occur is\nfound to be always less than 7%. For avalanches with a total mass of 4 kg we\nfind that, most of the time, the runout of a binary avalanche is larger than\nthe runout of monodisperse avalanches of corresponding constituent particles,\ndue to lubrication on the coarse-dominated side or to drag by inertial\nparticles on the fine-dominated side.\n",
"title": "Runout transition and clustering instability observed in binary-mixture avalanche deposits"
} | null | null | [
"Physics"
]
| null | true | null | 1901 | null | Validated | null | null |
null | {
"abstract": " Given a set of $n$ points $P$ in the plane, the first layer $L_1$ of $P$ is\nformed by the points that appear on $P$'s convex hull. In general, a point\nbelongs to layer $L_i$, if it lies on the convex hull of the set $P \\setminus\n\\bigcup_{j<i}\\{L_j\\}$. The \\emph{convex layers problem} is to compute the\nconvex layers $L_i$. Existing algorithms for this problem either do not achieve\nthe optimal $\\mathcal{O}\\left(n\\log n\\right)$ runtime and linear space, or are\noverly complex and difficult to apply in practice. We propose a new algorithm\nthat is both optimal and simple. The simplicity is achieved by independently\ncomputing four sets of monotone convex chains in $\\mathcal{O}\\left(n\\log\nn\\right)$ time and linear space. These are then merged in\n$\\mathcal{O}\\left(n\\log n\\right)$ time.\n",
"title": "A Simple Convex Layers Algorithm"
} | null | null | null | null | true | null | 1902 | null | Default | null | null |
null | {
"abstract": " This paper mainly focus on the front-like entire solution of a classical\nnonlocal dispersal equation with ignition nonlinearity. Especially, the\ndispersal kernel function $J$ may not be symmetric here. The asymmetry of $J$\nhas a great influence on the profile of the traveling waves and the sign of the\nwave speeds, which further makes the properties of the entire solution more\ndiverse. We first investigate the asymptotic behavior of the traveling wave\nsolutions since it plays an essential role in obtaining the front-like entire\nsolution. Due to the impact of $f'(0)=0$, we can no longer use the common\nmethod which mainly depending on Ikehara theorem and bilateral Laplace\ntransform to study the asymptotic rates of the nondecreasing traveling wave and\nthe nonincreasing one tending to 0, respectively, thus we adopt another method\nto investigate them. Afterwards, we establish a new entire solution and obtain\nits qualitative properties by constructing proper supersolution and subsolution\nand by classifying the sign and size of the wave speeds.\n",
"title": "Entire Solution in an Ignition Nonlocal Dispersal Equation: Asymmetric Kernel"
} | null | null | null | null | true | null | 1903 | null | Default | null | null |
null | {
"abstract": " In this paper, we classify the fundamental solutions for a class of\nSchrodinger operators.\n",
"title": "Fundamental solutions for Schrodinger operators with general inverse square potentials"
} | null | null | null | null | true | null | 1904 | null | Default | null | null |
null | {
"abstract": " To predict the final result of an athlete in a marathon run thoroughly is the\neternal desire of each trainer. Usually, the achieved result is weaker than the\npredicted one due to the objective (e.g., environmental conditions) as well as\nsubjective factors (e.g., athlete's malaise). Therefore, making up for the\ndeficit between predicted and achieved results is the main ingredient of the\nanalysis performed by trainers after the competition. In the analysis, they\nsearch for parts of a marathon course where the athlete lost time. This paper\nproposes an automatic making up for the deficit by using a Differential\nEvolution algorithm. In this case study, the results that were obtained by a\nwearable sports-watch by an athlete in a real marathon are analyzed. The first\nexperiments with Differential Evolution show the possibility of using this\nmethod in the future.\n",
"title": "Making up for the deficit in a marathon run"
} | null | null | [
"Computer Science"
]
| null | true | null | 1905 | null | Validated | null | null |
null | {
"abstract": " Nowadays, multiprocessing is mainstream with exponentially increasing number\nof processors. Load balancing is, therefore, a critical operation for the\nefficient execution of parallel algorithms. In this paper we consider the\nfundamental class of tree-based algorithms that are notoriously irregular, and\nhard to load-balance with existing static techniques. We propose a hybrid load\nbalancing method using the utility of statistical random sampling in estimating\nthe tree depth and node count distributions to uniformly partition an input\ntree. To conduct an initial performance study, we implemented the method on an\nIntel Xeon Phi accelerator system. We considered the tree traversal operation\non both regular and irregular unbalanced trees manifested by Fibonacci and\nunbalanced (biased) randomly generated trees, respectively. The results show\nscalable performance for up to the 60 physical processors of the accelerator,\nas well as an extrapolated 128 processors case.\n",
"title": "An Efficient Load Balancing Method for Tree Algorithms"
} | null | null | null | null | true | null | 1906 | null | Default | null | null |
null | {
"abstract": " We study the dynamics of an isotropic spin-1/2 Heisenberg chain starting in a\ndomain-wall initial condition, where the spins are initially up on the left\nhalf-line and down on the right half-line. We focus on the long-time behavior\nof the magnetization profile. We perform extensive time-dependent\ndensity-matrix renormalization group simulations (up to t=350) and find that\nthe data are compatible with a diffusive behavior. Subleading corrections decay\nslowly blurring the emergence of the diffusive behavior. We also compare our\nresults with two alternative scenarios: superdiffusive behavior and enhanced\ndiffusion with a logarithmic correction. We finally discuss the evolution of\nthe entanglement entropy.\n",
"title": "Dynamics of the spin-1/2 Heisenberg chain initialized in a domain-wall state"
} | null | null | null | null | true | null | 1907 | null | Default | null | null |
null | {
"abstract": " Erasure codes play an important role in storage systems to prevent data loss.\nIn this work, we study a class of erasure codes called Multi-Erasure Locally\nRecoverable Codes (ME-LRCs) for flash memory array. Compared to previous\nrelated works, we focus on the construction of ME-LRCs over small fields. We\nfirst develop upper and lower bounds on the minimum distance of ME-LRCs. These\nbounds explicitly take the field size into account. Our main contribution is to\npropose a general construction of ME-LRCs based on generalized tensor product\ncodes, and study their erasure-correcting property. A decoding algorithm\ntailored for erasure recovery is given. We then prove that our construction\nyields optimal ME-LRCs with a wide range of code parameters. Finally, we\npresent several families of ME-LRCs over different fields.\n",
"title": "Multi-Erasure Locally Recoverable Codes Over Small Fields For Flash Memory Array"
} | null | null | null | null | true | null | 1908 | null | Default | null | null |
null | {
"abstract": " Machine learning libraries such as TensorFlow and PyTorch simplify model\nimplementation. However, researchers are still required to perform a\nnon-trivial amount of manual tasks such as GPU allocation, training status\ntracking, and comparison of models with different hyperparameter settings. We\npropose a system to handle these tasks and help researchers focus on models. We\npresent the requirements of the system based on a collection of discussions\nfrom an online study group comprising 25k members. These include automatic GPU\nallocation, learning status visualization, handling model parameter snapshots\nas well as hyperparameter modification during learning, and comparison of\nperformance metrics between models via a leaderboard. We describe the system\narchitecture that fulfills these requirements and present a proof-of-concept\nimplementation, NAVER Smart Machine Learning (NSML). We test the system and\nconfirm substantial efficiency improvements for model development.\n",
"title": "NSML: A Machine Learning Platform That Enables You to Focus on Your Models"
} | null | null | null | null | true | null | 1909 | null | Default | null | null |
null | {
"abstract": " We devise a new high order local absorbing boundary condition (ABC) for\nradiating problems and scattering of time-harmonic acoustic waves from\nobstacles of arbitrary shape. By introducing an artificial boundary $S$\nenclosing the scatterer, the original unbounded domain $\\Omega$ is decomposed\ninto a bounded computational domain $\\Omega^{-}$ and an exterior unbounded\ndomain $\\Omega^{+}$. Then, we define interface conditions at the artificial\nboundary $S$, from truncated versions of the well-known Wilcox and Karp\nfarfield expansion representations of the exact solution in the exterior region\n$\\Omega^{+}$. As a result, we obtain a new local absorbing boundary condition\n(ABC) for a bounded problem on $\\Omega^{-}$, which effectively accounts for the\noutgoing behavior of the scattered field. Contrary to the low order absorbing\nconditions previously defined, the order of the error induced by this ABC can\neasily match the order of the numerical method in $\\Omega^{-}$. We accomplish\nthis by simply adding as many terms as needed to the truncated farfield\nexpansions of Wilcox or Karp. The convergence of these expansions guarantees\nthat the order of approximation of the new ABC can be increased arbitrarily\nwithout having to enlarge the radius of the artificial boundary. We include\nnumerical results in two and three dimensions which demonstrate the improved\naccuracy and simplicity of this new formulation when compared to other\nabsorbing boundary conditions.\n",
"title": "High order local absorbing boundary conditions for acoustic waves in terms of farfield expansions"
} | null | null | null | null | true | null | 1910 | null | Default | null | null |
null | {
"abstract": " We describe some necessary conditions for the existence of a Hamiltonian path\nin any graph (in other words, for a graph to be traceable). These conditions\nresult in a linear time algorithm to decide the Hamiltonian path problem for\ncactus graphs. We apply this algorithm to several molecular databases to report\nthe numbers of graphs that are traceable cactus graphs.\n",
"title": "Simple Necessary Conditions for the Existence of a Hamiltonian Path with Applications to Cactus Graphs"
} | null | null | [
"Computer Science"
]
| null | true | null | 1911 | null | Validated | null | null |
null | {
"abstract": " We introduce two new bootstraps for exchangeable random graphs. One, the\n\"empirical graphon\", is based purely on resampling, while the other, the\n\"histogram stochastic block model\", is a model-based \"sieve\" bootstrap. We show\nthat both of them accurately approximate the sampling distributions of motif\ndensities, i.e., of the normalized counts of the number of times fixed\nsubgraphs appear in the network. These densities characterize the distribution\nof (infinite) exchangeable networks. Our bootstraps therefore give, for the\nfirst time, a valid quantification of uncertainty in inferences about\nfundamental network statistics, and so of parameters identifiable from them.\n",
"title": "Bootstrapping Exchangeable Random Graphs"
} | null | null | null | null | true | null | 1912 | null | Default | null | null |
null | {
"abstract": " In this paper, we shall prove that any subset of $\\overline{\\mathbb Q}\\cap\nB(0,1)$, which is closed under complex conjugation and which contains the\nelement $0$, is the exceptional set of uncountably many transcendental\nfunctions, analytic in the unit ball, with integer coefficients. This solves a\nstrong version of an old question proposed by K. Mahler (1976).\n",
"title": "A question proposed by K. Mahler on exceptional sets of transcendental functions with integer coefficients: solution of a Mahler's problem"
} | null | null | null | null | true | null | 1913 | null | Default | null | null |
null | {
"abstract": " We present $\\texttt{BHM}$, a tool for restoring a smooth function from a\nsampled histogram using the bin hierarchy method. The theoretical background of\nthe method is presented in [arXiv:1707.07625]. The code automatically generates\na smooth polynomial spline with the minimal acceptable number of knots from the\ninput data. It works universally for any sufficiently regular shaped\ndistribution and any level of data quality, requiring almost no external\nparameter specification. It is particularly useful for large-scale numerical\ndata analysis. This paper explains the details of the implementation and the\nuse of the program.\n",
"title": "Implementation of the Bin Hierarchy Method for restoring a smooth function from a sampled histogram"
} | null | null | null | null | true | null | 1914 | null | Default | null | null |
null | {
"abstract": " We develop a general polynomial chaos (gPC) based stochastic Galerkin (SG)\nfor hyperbolic equations with random and singular coefficients. Due to the\nsingu- lar nature of the solution, the standard gPC-SG methods may suffer from\na poor or even non convergence. Taking advantage of the fact that the discrete\nsolution, by the central type finite difference or finite volume approximations\nin space and time for example, is smoother, we first discretize the equation by\na smooth finite difference or finite volume scheme, and then use the gPC-SG\napproximation to the discrete system. The jump condition at the interface is\ntreated using the immersed upwind methods introduced in [8, 12]. This yields a\nmethod that converges with the spectral accuracy for finite mesh size and time\nstep. We use a linear hyperbolic equation with discontinuous and random\ncoefficient, and the Liouville equation with discontinuous and random\npotential, to illustrate our idea, with both one and second order spatial\ndiscretizations. Spectral convergence is established for the first equation,\nand numerical examples for both equations show the desired accu- racy of the\nmethod.\n",
"title": "The Discrete Stochastic Galerkin Method for Hyperbolic Equations with Non-smooth and Random Coefficients"
} | null | null | null | null | true | null | 1915 | null | Default | null | null |
null | {
"abstract": " We study the seasonal evolution of Titan's lower stratosphere (around\n15~mbar) in order to better understand the atmospheric dynamics and chemistry\nin this part of the atmosphere. We analysed Cassini/CIRS far-IR observations\nfrom 2006 to 2016 in order to measure the seasonal variations of three\nphotochemical by-products: $\\mathrm{C_4H_2}$, $\\mathrm{C_3H_4}$, and\n$\\mathrm{C_2N_2}$. We show that the abundances of these three gases have\nevolved significantly at northern and southern high latitudes since 2006. We\nmeasure a sudden and steep increase of the volume mixing ratios of\n$\\mathrm{C_4H_2}$, $\\mathrm{C_3H_4}$, and $\\mathrm{C_2N_2}$ at the south pole\nfrom 2012 to 2013, whereas the abundances of these gases remained approximately\nconstant at the north pole over the same period. At northern mid-latitudes,\n$\\mathrm{C_2N_2}$ and $\\mathrm{C_4H_2}$ abundances decrease after 2012 while\n$\\mathrm{C_3H_4}$ abundances stay constant. The comparison of these volume\nmixing ratio variations with the predictions of photochemical and dynamical\nmodels provides constraints on the seasonal evolution of atmospheric\ncirculation and chemical processes at play.\n",
"title": "Seasonal evolution of $\\mathrm{C_2N_2}$, $\\mathrm{C_3H_4}$, and $\\mathrm{C_4H_2}$ abundances in Titan's lower stratosphere"
} | null | null | null | null | true | null | 1916 | null | Default | null | null |
null | {
"abstract": " Multi-agent approach has become popular in computer science and technology.\nHowever, the conventional models of multi-agent and multicomponent systems\nimplicitly or explicitly assume existence of absolute time or even do not\ninclude time in the set of defining parameters. At the same time, it is proved\ntheoretically and validated experimentally that there are different times and\ntime scales in a variety of real systems - physical, chemical, biological,\nsocial, informational, etc. Thus, the goal of this work is construction of a\nmulti-agent multicomponent system models with concurrency of processes and\ndiversity of actions. To achieve this goal, a mathematical system actor model\nis elaborated and its properties are studied.\n",
"title": "Systems, Actors and Agents: Operation in a multicomponent environment"
} | null | null | null | null | true | null | 1917 | null | Default | null | null |
null | {
"abstract": " We present an introductory survey to first order logic for metric structures\nand its applications to C*-algebras.\n",
"title": "An invitation to model theory and C*-algebras"
} | null | null | null | null | true | null | 1918 | null | Default | null | null |
null | {
"abstract": " The Percus-Yevick theory for monodisperse hard spheres gives very good\nresults for the pressure and structure factor of the system in a whole range of\ndensities that lie within the liquid phase. However, the equation seems to lead\nto a very unacceptable result beyond that region. Namely, the Percus-Yevick\ntheory predicts a smooth behavior of the pressure that diverges only when the\nvolume fraction $\\eta$ approaches unity. Thus, within the theory there seems to\nbe no indication for the termination of the liquid phase and the transition to\na solid or to a glass. In the present article we study the Percus-Yevick hard\nsphere pair distribution function, $g_2(r)$, for various spatial dimensions. We\nfind that beyond a certain critical volume fraction $\\eta_c$, the pair\ndistribution function, $g_2(r)$, which should be positive definite, becomes\nnegative at some distances. We also present an intriguing observation that the\ncritical $\\eta_c$ values we find are consistent with volume fractions where\nonsets of random close packing (or maximally random jammed states) are reported\nin the literature for various dimensions. That observation is supported by an\nintuitive argument. This work may have important implications for other systems\nfor which a Percus-Yevick theory exists.\n",
"title": "Random Close Packing and the Hard Sphere Percus-Yevick Theory"
} | null | null | null | null | true | null | 1919 | null | Default | null | null |
null | {
"abstract": " We test the $\\mathbb{C}P^{N-1}$ sigma models for the Painlevé property.\nWhile the construction of finite action solutions ensures their meromorphicity,\nthe general case requires testing. The test is performed for the equations in\nthe homogeneous variables, with their first component normalised to one. No\nconstraints are imposed on the dimensionality of the model or the values of the\ninitial exponents. This makes the test nontrivial, as the number of equations\nand dependent variables are indefinite. A $\\mathbb{C}P^{N-1}$ system proves to\nhave a $(4N-5)$-parameter family of solutions whose movable singularities are\nonly poles, while the order of the investigated system is $4N-4$. The remaining\ndegree of freedom, connected with an extra negative resonance, may correspond\nto a branching movable essential singularity. An example of such a solution is\nprovided.\n",
"title": "The Painlevé property of $\\mathbb{C}P^{N-1}$ sigma models"
} | null | null | null | null | true | null | 1920 | null | Default | null | null |
null | {
"abstract": " In the framework of matrix valued observables with low rank means, Stein's\nunbiased risk estimate (SURE) can be useful for risk estimation and for tuning\nthe amount of shrinkage towards low rank matrices. This was demonstrated by\nCandès et al. (2013) for singular value soft thresholding, which is a\nLipschitz continuous estimator. SURE provides an unbiased risk estimate for an\nestimator whenever the differentiability requirements for Stein's lemma are\nsatisfied. Lipschitz continuity of the estimator is sufficient, but it is\nemphasized that differentiability Lebesgue almost everywhere isn't. The reduced\nrank estimator, which gives the best approximation of the observation with a\nfixed rank, is an example of a discontinuous estimator for which Stein's lemma\nactually applies. This was observed by Mukherjee et al. (2015), but the proof\nwas incomplete. This brief note gives a sufficient condition for Stein's lemma\nto hold for estimators with discontinuities, which is then shown to be\nfulfilled for a class of spectral function estimators including the reduced\nrank estimator. Singular value hard thresholding does, however, not satisfy the\ncondition, and Stein's lemma does not apply to this estimator.\n",
"title": "A comment on Stein's unbiased risk estimate for reduced rank estimators"
} | null | null | null | null | true | null | 1921 | null | Default | null | null |
null | {
"abstract": " Evaluating generative adversarial networks (GANs) is inherently challenging.\nIn this paper, we revisit several representative sample-based evaluation\nmetrics for GANs, and address the problem of how to evaluate the evaluation\nmetrics. We start with a few necessary conditions for metrics to produce\nmeaningful scores, such as distinguishing real from generated samples,\nidentifying mode dropping and mode collapsing, and detecting overfitting. With\na series of carefully designed experiments, we comprehensively investigate\nexisting sample-based metrics and identify their strengths and limitations in\npractical settings. Based on these results, we observe that kernel Maximum Mean\nDiscrepancy (MMD) and the 1-Nearest-Neighbor (1-NN) two-sample test seem to\nsatisfy most of the desirable properties, provided that the distances between\nsamples are computed in a suitable feature space. Our experiments also unveil\ninteresting properties about the behavior of several popular GAN models, such\nas whether they are memorizing training samples, and how far they are from\nlearning the target distribution.\n",
"title": "An empirical study on evaluation metrics of generative adversarial networks"
} | null | null | null | null | true | null | 1922 | null | Default | null | null |
null | {
"abstract": " The intersecting pedestrian flow on the 2D lattice with random update rule is\nstudied. Each pedestrian has three moving directions without the back step.\nUnder periodic boundary conditions, an intermediate phase has been found at\nwhich some pedestrians could move along the border of jamming stripes. We have\nperformed mean field analysis for the moving and intermediate phase\nrespectively. The analytical results agree with the simulation results well.\nThe empty site moves along the interface of jamming stripes when the system\nonly has one empty site. The average movement of empty site in one Monte Carlo\nstep (MCS) has been analyzed through the master equation. Under open boundary\nconditions, the system exhibits moving and jamming phases. The critical\ninjection probability $\\alpha_c$ shows nontrivially against the forward moving\nprobability $q$. The analytical results of average velocity, the density and\nthe flow rate against the injection probability in the moving phase also agree\nwith simulation results well.\n",
"title": "Analytical and simulation studies of pedestrian flow at a crossing with random update rule"
} | null | null | null | null | true | null | 1923 | null | Default | null | null |
null | {
"abstract": " LiOsO$_3$ is the first example of a new class of material called a\nferroelectric metal. We performed zero-field and longitudinal-field $\\mu$SR,\nalong with a combination of electronic structure and dipole field calculations,\nto determine the magnetic ground state of LiOsO$_3$. We find that the sample\ncontains both static Li nuclear moments and dynamic Os electronic moments.\nBelow $\\approx 0.7\\,$K, the fluctuations of the Os moments slow down, though\nremain dynamic down to 0.08$\\,$K. We expect this could result in a frozen-out,\ndisordered ground state at even lower temperatures.\n",
"title": "Static and Fluctuating Magnetic Moments in the Ferroelectric Metal LiOsO$_3$"
} | null | null | null | null | true | null | 1924 | null | Default | null | null |
null | {
"abstract": " Convolutional neural networks (CNNs) are the core of most state-of-the-art\ndeep learning algorithms specialized for object detection and classification.\nCNNs are both computationally complex and embarrassingly parallel. Two\nproperties that leave room for potential software and hardware optimizations\nfor embedded systems. Given a programmable hardware accelerator with a CNN\noriented custom instructions set, the compiler's task is to exploit the\nhardware's full potential, while abiding with the hardware constraints and\nmaintaining generality to run different CNN models with varying workload\nproperties. Snowflake is an efficient and scalable hardware accelerator\nimplemented on programmable logic devices. It implements a control pipeline for\na custom instruction set. The goal of this paper is to present Snowflake's\ncompiler that generates machine level instructions from Torch7 model\ndescription files. The main software design points explored in this work are:\nmodel structure parsing, CNN workload breakdown, loop rearrangement for memory\nbandwidth optimizations and memory access balancing. The performance achieved\nby compiler generated instructions matches against hand optimized code for\nconvolution layers. Generated instructions also efficiently execute AlexNet and\nResNet18 inference on Snowflake. Snowflake with $256$ processing units was\nsynthesized on Xilinx's Zynq XC7Z045 FPGA. At $250$ MHz, AlexNet achieved in\n$93.6$ frames/s and $1.2$ GB/s of off-chip memory bandwidth, and $21.4$\nframes/s and $2.2$ GB/s for ResNet18. Total on-chip power is $5$ W.\n",
"title": "Compiling Deep Learning Models for Custom Hardware Accelerators"
} | null | null | null | null | true | null | 1925 | null | Default | null | null |
null | {
"abstract": " Retrieving the most similar objects in a large-scale database for a given\nquery is a fundamental building block in many application domains, ranging from\nweb searches, visual, cross media, and document retrievals. State-of-the-art\napproaches have mainly focused on capturing the underlying geometry of the data\nmanifolds. Graph-based approaches, in particular, define various diffusion\nprocesses on weighted data graphs. Despite success, these approaches rely on\nfixed-weight graphs, making ranking sensitive to the input affinity matrix. In\nthis study, we propose a new ranking algorithm that simultaneously learns the\ndata affinity matrix and the ranking scores. The proposed optimization\nformulation assigns adaptive neighbors to each point in the data based on the\nlocal connectivity, and the smoothness constraint assigns similar ranking\nscores to similar data points. We develop a novel and efficient algorithm to\nsolve the optimization problem. Evaluations using synthetic and real datasets\nsuggest that the proposed algorithm can outperform the existing methods.\n",
"title": "Ranking with Adaptive Neighbors"
} | null | null | null | null | true | null | 1926 | null | Default | null | null |
null | {
"abstract": " Let $A$ be a finite dimensional real algebra with a division grading by a\nfinite abelian group $G$. In this paper we provide finite basis for the\n$T_G$-ideal of graded identities and for the $T_G$-space of graded central\npolynomials for $A$.\n",
"title": "Identities and central polynomials of real graded division algebras"
} | null | null | null | null | true | null | 1927 | null | Default | null | null |
null | {
"abstract": " In this paper, we first discuss the relation between VB-Courant algebroids\nand E-Courant algebroids and construct some examples of E-Courant algebroids.\nThen we introduce the notion of a generalized complex structure on an E-Courant\nalgebroid, unifying the usual generalized complex structures on\neven-dimensional manifolds and generalized contact structures on\nodd-dimensional manifolds. Moreover, we study generalized complex structures on\nan omni-Lie algebroid in detail. In particular, we show that generalized\ncomplex structures on an omni-Lie algebra $\\gl(V)\\oplus V$ correspond to\ncomplex Lie algebra structures on V.\n",
"title": "VB-Courant algebroids, E-Courant algebroids and generalized geometry"
} | null | null | null | null | true | null | 1928 | null | Default | null | null |
null | {
"abstract": " We consider a Josephson junction consisting of superconductor/ferromagnetic\ninsulator (S/FI) bilayers as electrodes which proximizes a nearby 2D electron\ngas. By starting from a generic Josephson hybrid planar setup we present an\nexhaustive analysis of the the interplay between the superconducting and\nmagnetic proximity effects and the conditions under which the structure\nundergoes transitions to a non-trivial topological phase. We address the 2D\nbound state problem using a general transfer matrix approach that reduces the\nproblem to an effective 1D Hamiltonian. This allows for straightforward study\nof topological properties in different symmetry classes. As an example we\nconsider a narrow channel coupled with multiple ferromagnetic superconducting\nfingers, and discuss how the Majorana bound states can be spatially controlled\nby tuning the superconducting phases. Following our approach we also show the\nenergy spectrum, the free energy and finally the multiterminal Josephson\ncurrent of the setup.\n",
"title": "Majorana bound states in hybrid 2D Josephson junctions with ferromagnetic insulators"
} | null | null | null | null | true | null | 1929 | null | Default | null | null |
null | {
"abstract": " Rashba spin orbit coupling in topological insulators has attracted much\ninterest due to its exotic properties closely related to spintronic devices.\nThe coexistence of nontrivial topology and giant Rashba splitting, however, has\nrare been observed in two-dimensional films, limiting severely its potential\napplications at room temperature. Here, we propose a series of inversion\nasymmetric group IV films, ABZ2, whose stability are confirmed by phonon\nspectrum calculations. The analyses of electronic structures reveal that they\nare intrinsic 2D TIs with a bulk gap as large as 0.74 eV, except for GeSiF2,\nSnSiCl2, GeSiCl2 and GeSiBr2 monolayers which can transform from normal to\ntopological phases under appropriate tensile strains. Another prominent\nintriguing feature is the giant Rashba spin splitting with a magnitude reaching\n0.15 eV, the largest value reported in 2D films. These results present a\nplatform to explore 2D TIs for room temperature device applications.\n",
"title": "Two-Dimensional Large Gap Topological Insulators with Large Rashba Spin-Orbit Coupling in Group-IV films"
} | null | null | null | null | true | null | 1930 | null | Default | null | null |
null | {
"abstract": " A Floquet systems is a periodically driven quantum system. It can be\ndescribed by a Floquet operator. If this unitary operator has a gap in the\nspectrum, then one can define associated topological bulk invariants which can\neither only depend on the bands of the Floquet operator or also on the time as\na variable. It is shown how a K-theoretic result combined with the\nbulk-boundary correspondence leads to edge invariants for the half-space\nFloquet operators. These results also apply to topological quantum walks.\n",
"title": "Topological boundary invariants for Floquet systems and quantum walks"
} | null | null | null | null | true | null | 1931 | null | Default | null | null |
null | {
"abstract": " This paper maps out the relation between different approaches for handling\npreferences in argumentation with strict rules and defeasible assumptions by\noffering translations between them. The systems we compare are: non-prioritized\ndefeats i.e. attacks, preference-based defeats, and preference-based defeats\nextended with reverse defeat.\n",
"title": "Assumption-Based Approaches to Reasoning with Priorities"
} | null | null | null | null | true | null | 1932 | null | Default | null | null |
null | {
"abstract": " In this work, we consider diffusion-based molecular communication with and\nwithout drift between two static nano-machines. We employ type-based\ninformation encoding, releasing a single molecule per information bit. At the\nreceiver, we consider an asynchronous detection algorithm which exploits the\narrival order of the molecules. In such systems, transposition errors\nfundamentally undermine reliability and capacity. Thus, in this work we study\nthe impact of transpositions on the system performance. Towards this, we\npresent an analytical expression for the exact bit error probability (BEP)\ncaused by transpositions and derive computationally tractable approximations of\nthe BEP for diffusion-based channels with and without drift. Based on these\nresults, we analyze the BEP when background is not negligible and derive the\noptimal bit interval that minimizes the BEP. Simulation results confirm the\ntheoretical results and show the error and goodput performance for different\nparameters such as block size or noise generation rate.\n",
"title": "On the Impact of Transposition Errors in Diffusion-Based Channels"
} | null | null | null | null | true | null | 1933 | null | Default | null | null |
null | {
"abstract": " We define variable parameter analogues of the affine arclength measure on\ncurves and prove near-optimal $L^p$-improving estimates for associated\nmultilinear generalized Radon transforms. Some of our results are new even in\nthe convolution case.\n",
"title": "Uniform $L^p$-improving for weighted averages on curves"
} | null | null | null | null | true | null | 1934 | null | Default | null | null |
null | {
"abstract": " We study the problem of estimating finite sample confidence intervals of the\nmean of a normal population under the constraint of differential privacy. We\nconsider both the known and unknown variance cases and construct differentially\nprivate algorithms to estimate confidence intervals. Crucially, our algorithms\nguarantee a finite sample coverage, as opposed to an asymptotic coverage.\nUnlike most previous differentially private algorithms, we do not require the\ndomain of the samples to be bounded. We also prove lower bounds on the expected\nsize of any differentially private confidence set showing that our the\nparameters are optimal up to polylogarithmic factors.\n",
"title": "Finite Sample Differentially Private Confidence Intervals"
} | null | null | null | null | true | null | 1935 | null | Default | null | null |
null | {
"abstract": " Extreme-scale computational science increasingly demands multiscale and\nmultiphysics formulations. Combining software developed by independent groups\nis imperative: no single team has resources for all predictive science and\ndecision support capabilities. Scientific libraries provide high-quality,\nreusable software components for constructing applications with improved\nrobustness and portability. However, without coordination, many libraries\ncannot be easily composed. Namespace collisions, inconsistent arguments, lack\nof third-party software versioning, and additional difficulties make\ncomposition costly.\nThe Extreme-scale Scientific Software Development Kit (xSDK) defines\ncommunity policies to improve code quality and compatibility across\nindependently developed packages (hypre, PETSc, SuperLU, Trilinos, and\nAlquimia) and provides a foundation for addressing broader issues in software\ninteroperability, performance portability, and sustainability. The xSDK\nprovides turnkey installation of member software and seamless combination of\naggregate capabilities, and it marks first steps toward extreme-scale\nscientific software ecosystems from which future applications can be composed\nrapidly with assured quality and scalability.\n",
"title": "xSDK Foundations: Toward an Extreme-scale Scientific Software Development Kit"
} | null | null | null | null | true | null | 1936 | null | Default | null | null |
null | {
"abstract": " Uranium beryllium-13 is a heavy fermion system whose anomalous behavior may\nbe explained by its poorly understood internal magnetic structure. Here,\nuranium beryllium-13's magnetic distribution is probed via muon spin\nspectroscopy ($\\mu$SR)-a process where positive muons localize at magnetically\nunique sites in the crystal lattice and precess at characteristic Larmor\nfrequencies, providing measurements of the internal field. Muon spin\nexperiments using the transverse-field technique conducted at varying\ntemperatures and external magnetic field strengths are analyzed via statistical\nmethods on ROOT. Two precession frequencies are observed at low temperatures\nwith an amplitude ratio in the Fourier transform of 2:1, enabling muon stopping\nsites to be traced at the geometric centers of the edges of the crystal\nlattice. Characteristic strong and weak magnetic sites are deduced,\nadditionally verified by mathematical relationships. Results can readily be\napplied to other heavy fermion systems, and recent identification of quantum\ncritical points in a host of heavy fermion compounds show a promising future\nfor the application of these systems in quantum technology. Note that this\npaper is an analysis of data, and all experiments mentioned here are conducted\nby a third party.\n",
"title": "Muon Spin Rotation Analysis of the Internal Magnetic Field of Heavy Fermion System Uranium Beryllium-13"
} | null | null | null | null | true | null | 1937 | null | Default | null | null |
null | {
"abstract": " In this article we study the behavior as $p \\nearrow+\\infty$ of the Fucik\nspectrum for $p$-Laplace operator with zero Dirichlet boundary conditions in a\nbounded domain $\\Omega\\subset \\mathbb{R}^n$. We characterize the limit\nequation, and we provide a description of the limit spectrum. Furthermore, we\nshow some explicit computations of the spectrum for certain configurations of\nthe domain.\n",
"title": "The infinity-Fucik spectrum"
} | null | null | null | null | true | null | 1938 | null | Default | null | null |
null | {
"abstract": " We show that a finite unitary group which has orbits spanning the whole space\nis necessarily the setwise stabilizer of a certain orbit.\n",
"title": "Unitary Groups as Stabilizers of Orbits"
} | null | null | null | null | true | null | 1939 | null | Default | null | null |
null | {
"abstract": " Multivariate time series (MTS) have become increasingly common in healthcare\ndomains where human vital signs and laboratory results are collected for\npredictive diagnosis. Recently, there have been increasing efforts to visualize\nhealthcare MTS data based on star charts or parallel coordinates. However, such\ntechniques might not be ideal for visualizing a large MTS dataset, since it is\ndifficult to obtain insights or interpretations due to the inherent high\ndimensionality of MTS. In this paper, we propose 'm-TSNE': a simple and novel\nframework to visualize high-dimensional MTS data by projecting them into a\nlow-dimensional (2-D or 3-D) space while capturing the underlying data\nproperties. Our framework is easy to use and provides interpretable insights\nfor healthcare professionals to understand MTS data. We evaluate our\nvisualization framework on two real-world datasets and demonstrate that the\nresults of our m-TSNE show patterns that are easy to understand while the other\nmethods' visualization may have limitations in interpretability.\n",
"title": "m-TSNE: A Framework for Visualizing High-Dimensional Multivariate Time Series"
} | null | null | null | null | true | null | 1940 | null | Default | null | null |
null | {
"abstract": " For parabolic equations of the form $$ \\frac{\\partial u}{\\partial t} -\n\\sum_{i,j=1}^n a_{ij} (x, u) \\frac{\\partial^2 u}{\\partial x_i \\partial x_j} + f\n(x, u, D u) = 0 \\quad \\mbox{in } {\\mathbb R}_+^{n+1}, $$ where ${\\mathbb\nR}_+^{n+1} = {\\mathbb R}^n \\times (0, \\infty)$, $n \\ge 1$, $D = (\\partial /\n\\partial x_1, \\ldots, \\partial / \\partial x_n)$ is the gradient operator, and\n$f$ is some function, we obtain conditions guaranteeing that every solution\ntends to zero as $t \\to \\infty$.\n",
"title": "On stabilization of solutions of nonlinear parabolic equations with a gradient term"
} | null | null | null | null | true | null | 1941 | null | Default | null | null |
null | {
"abstract": " Many radiological studies can reveal the presence of several co-existing\nabnormalities, each one represented by a distinct visual pattern. In this\narticle we address the problem of learning a distance metric for plain\nradiographs that captures a notion of \"radiological similarity\": two chest\nradiographs are considered to be similar if they share similar abnormalities.\nDeep convolutional neural networks (DCNs) are used to learn a low-dimensional\nembedding for the radiographs that is equipped with the desired metric. Two\nloss functions are proposed to deal with multi-labelled images and potentially\nnoisy labels. We report on a large-scale study involving over 745,000 chest\nradiographs whose labels were automatically extracted from free-text\nradiological reports through a natural language processing system. Using 4,500\nvalidated exams, we demonstrate that the methodology performs satisfactorily on\nclustering and image retrieval tasks. Remarkably, the learned metric separates\nnormal exams from those having radiological abnormalities.\n",
"title": "Deep metric learning for multi-labelled radiographs"
} | null | null | null | null | true | null | 1942 | null | Default | null | null |
null | {
"abstract": " We provide a complete classification of all algebras of generalised dihedral\ntype, which are natural generalizations of algebras which occurred in the study\nof blocks with dihedral defect groups. This gives a description by quivers and\nrelations coming from surface triangulations.\n",
"title": "Algebras of generalized dihedral type"
} | null | null | [
"Mathematics"
]
| null | true | null | 1943 | null | Validated | null | null |
null | {
"abstract": " We revisit the study of the phenomenology associated to a burst of particle\nproduction of a field whose mass is controlled by the inflaton field and\nvanishes at one given instance during inflation. This generates a bump in the\ncorrelators of the primordial scalar curvature. We provide a unified formalism\nto compute various effects that have been obtained in the literature and\nconfirm that the dominant effects are due to the rescattering of the produced\nparticles on the inflaton condensate. We improve over existing results (based\non numerical fits) by providing exact analytic expressions for the shape and\nheight of the bump, both in the power spectrum and the equilateral bispectrum.\nWe then study the regime of validity of the perturbative computations of this\nsignature. Finally, we extend these computations to the case of a burst of\nparticle production in a sector coupled only gravitationally to the inflaton.\n",
"title": "Resonant particle production during inflation: a full analytical study"
} | null | null | null | null | true | null | 1944 | null | Default | null | null |
null | {
"abstract": " Consider the following asynchronous, opportunistic communication model over a\ngraph $G$: in each round, one edge is activated uniformly and independently at\nrandom and (only) its two endpoints can exchange messages and perform local\ncomputations. Under this model, we study the following random process: The\nfirst time a vertex is an endpoint of an active edge, it chooses a random\nnumber, say $\\pm 1$ with probability $1/2$; then, in each round, the two\nendpoints of the currently active edge update their values to their average. We\nshow that, if $G$ exhibits a two-community structure (for example, two\nexpanders connected by a sparse cut), the values held by the nodes will\ncollectively reflect the underlying community structure over a suitable phase\nof the above process, allowing efficient and effective recovery in important\ncases.\nIn more detail, we first provide a first-moment analysis showing that, for a\nlarge class of almost-regular clustered graphs that includes the stochastic\nblock model, the expected values held by all but a negligible fraction of the\nnodes eventually reflect the underlying cut signal. We prove this property\nemerges after a mixing period of length $\\mathcal O(n\\log n)$. We further\nprovide a second-moment analysis for a more restricted class of regular\nclustered graphs that includes the regular stochastic block model. For this\ncase, we are able to show that most nodes can efficiently and locally identify\ntheir community of reference over a suitable time window. This results in the\nfirst opportunistic protocols that approximately recover community structure\nusing only polylogarithmic work per node. Even for the above class of regular\ngraphs, our second moment analysis requires new concentration bounds on the\nproduct of certain random matrices that are technically challenging and\npossibly of independent interest.\n",
"title": "Average whenever you meet: Opportunistic protocols for community detection"
} | null | null | null | null | true | null | 1945 | null | Default | null | null |
null | {
"abstract": " We give a fully polynomial-time randomized approximation scheme (FPRAS) for\nthe all-terminal network reliability problem, which is to determine the\nprobability that, in a undirected graph, assuming each edge fails\nindependently, the remaining graph is still connected. Our main contribution is\nto confirm a conjecture by Gorodezky and Pak (Random Struct. Algorithms, 2014),\nthat the expected running time of the \"cluster-popping\" algorithm in\nbi-directed graphs is bounded by a polynomial in the size of the input.\n",
"title": "A polynomial-time approximation algorithm for all-terminal network reliability"
} | null | null | null | null | true | null | 1946 | null | Default | null | null |
null | {
"abstract": " Sparse coding is a crucial subroutine in algorithms for various signal\nprocessing, deep learning, and other machine learning applications. The central\ngoal is to learn an overcomplete dictionary that can sparsely represent a given\ninput dataset. However, a key challenge is that storage, transmission, and\nprocessing of the learned dictionary can be untenably high if the data\ndimension is high. In this paper, we consider the double-sparsity model\nintroduced by Rubinstein et al. (2010b) where the dictionary itself is the\nproduct of a fixed, known basis and a data-adaptive sparse component. First, we\nintroduce a simple algorithm for double-sparse coding that can be amenable to\nefficient implementation via neural architectures. Second, we theoretically\nanalyze its performance and demonstrate asymptotic sample complexity and\nrunning time benefits over existing (provable) approaches for sparse coding. To\nour knowledge, our work introduces the first computationally efficient\nalgorithm for double-sparse coding that enjoys rigorous statistical guarantees.\nFinally, we support our analysis via several numerical experiments on simulated\ndata, confirming that our method can indeed be useful in problem sizes\nencountered in practical applications.\n",
"title": "Provably Accurate Double-Sparse Coding"
} | null | null | [
"Computer Science",
"Statistics"
]
| null | true | null | 1947 | null | Validated | null | null |
null | {
"abstract": " Reduced-rank regression is a dimensionality reduction method with many\napplications. The asymptotic theory for reduced rank estimators of parameter\nmatrices in multivariate linear models has been studied extensively. In\ncontrast, few theoretical results are available for reduced-rank multivariate\ngeneralised linear models. We develop M-estimation theory for concave criterion\nfunctions that are maximised over parameters spaces that are neither convex nor\nclosed. These results are used to derive the consistency and asymptotic\ndistribution of maximum likelihood estimators in reduced-rank multivariate\ngeneralised linear models, when the response and predictor vectors have a joint\ndistribution. We illustrate our results in a real data classification problem\nwith binary covariates.\n",
"title": "Asymptotic theory for maximum likelihood estimates in reduced-rank multivariate generalised linear models"
} | null | null | null | null | true | null | 1948 | null | Default | null | null |
null | {
"abstract": " We find asymptotic formulas for error probabilities of two-fold Pearson\ngoodness-of-fit test as functions of two critical levels. These results may be\nreformulated in terms of tails of two-dimensional distributions of the Bessel\nprocess. Necessary properties of the Infeld function are obtained.\n",
"title": "Sequential two-fold Pearson chi-squared test and tails of the Bessel process distributions"
} | null | null | null | null | true | null | 1949 | null | Default | null | null |
null | {
"abstract": " The visual focus of attention (VFOA) has been recognized as a prominent\nconversational cue. We are interested in estimating and tracking the VFOAs\nassociated with multi-party social interactions. We note that in this type of\nsituations the participants either look at each other or at an object of\ninterest; therefore their eyes are not always visible. Consequently both gaze\nand VFOA estimation cannot be based on eye detection and tracking. We propose a\nmethod that exploits the correlation between eye gaze and head movements. Both\nVFOA and gaze are modeled as latent variables in a Bayesian switching\nstate-space model. The proposed formulation leads to a tractable learning\nprocedure and to an efficient algorithm that simultaneously tracks gaze and\nvisual focus. The method is tested and benchmarked using two publicly available\ndatasets that contain typical multi-party human-robot and human-human\ninteractions.\n",
"title": "Tracking Gaze and Visual Focus of Attention of People Involved in Social Interaction"
} | null | null | null | null | true | null | 1950 | null | Default | null | null |
null | {
"abstract": " We introduce the fully-dynamic conflict-free coloring problem for a set $S$\nof intervals in $\\mathbb{R}^1$ with respect to points, where the goal is to\nmaintain a conflict-free coloring for$S$ under insertions and deletions. A\ncoloring is conflict-free if for each point $p$ contained in some interval, $p$\nis contained in an interval whose color is not shared with any other interval\ncontaining $p$. We investigate trade-offs between the number of colors used and\nthe number of intervals that are recolored upon insertion or deletion of an\ninterval. Our results include:\n- a lower bound on the number of recolorings as a function of the number of\ncolors, which implies that with $O(1)$ recolorings per update the worst-case\nnumber of colors is $\\Omega(\\log n/\\log\\log n)$, and that any strategy using\n$O(1/\\varepsilon)$ colors needs $\\Omega(\\varepsilon n^{\\varepsilon})$\nrecolorings;\n- a coloring strategy that uses $O(\\log n)$ colors at the cost of $O(\\log n)$\nrecolorings, and another strategy that uses $O(1/\\varepsilon)$ colors at the\ncost of $O(n^{\\varepsilon}/\\varepsilon)$ recolorings;\n- stronger upper and lower bounds for special cases.\nWe also consider the kinetic setting where the intervals move continuously\n(but there are no insertions or deletions); here we show how to maintain a\ncoloring with only four colors at the cost of three recolorings per event and\nshow this is tight.\n",
"title": "Fully-Dynamic and Kinetic Conflict-Free Coloring of Intervals with Respect to Points"
} | null | null | null | null | true | null | 1951 | null | Default | null | null |
null | {
"abstract": " A systematic experimental study of Gilbert damping is performed via\nferromagnetic resonance for the disordered crystalline binary 3d transition\nmetal alloys Ni-Co, Ni-Fe and Co-Fe over the full range of alloy compositions.\nAfter accounting for inhomogeneous linewidth broadening, the damping shows\nclear evidence of both interfacial damping enhancement (by spin pumping) and\nradiative damping. We quantify these two extrinsic contributions and thereby\ndetermine the intrinsic damping. The comparison of the intrinsic damping to\nmultiple theoretical calculations yields good qualitative and quantitative\nagreement in most cases. Furthermore, the values of the damping obtained in\nthis study are in good agreement with a wide range of published experimental\nand theoretical values. Additionally, we find a compositional dependence of the\nspin mixing conductance.\n",
"title": "Magnetic properties in ultra-thin 3d transition metal alloys II: Experimental verification of quantitative theories of damping and spin-pumping"
} | null | null | null | null | true | null | 1952 | null | Default | null | null |
null | {
"abstract": " Learning to detect fraud in large-scale accounting data is one of the\nlong-standing challenges in financial statement audits or fraud investigations.\nNowadays, the majority of applied techniques refer to handcrafted rules derived\nfrom known fraud scenarios. While fairly successful, these rules exhibit the\ndrawback that they often fail to generalize beyond known fraud scenarios and\nfraudsters gradually find ways to circumvent them. To overcome this\ndisadvantage and inspired by the recent success of deep learning we propose the\napplication of deep autoencoder neural networks to detect anomalous journal\nentries. We demonstrate that the trained network's reconstruction error\nobtainable for a journal entry and regularized by the entry's individual\nattribute probabilities can be interpreted as a highly adaptive anomaly\nassessment. Experiments on two real-world datasets of journal entries, show the\neffectiveness of the approach resulting in high f1-scores of 32.93 (dataset A)\nand 16.95 (dataset B) and less false positive alerts compared to state of the\nart baseline methods. Initial feedback received by chartered accountants and\nfraud examiners underpinned the quality of the approach in capturing highly\nrelevant accounting anomalies.\n",
"title": "Detection of Anomalies in Large Scale Accounting Data using Deep Autoencoder Networks"
} | null | null | null | null | true | null | 1953 | null | Default | null | null |
null | {
"abstract": " We consider a problem of learning a binary classifier only from positive data\nand unlabeled data (PU learning) and estimating the class-prior in unlabeled\ndata under the case-control scenario. Most of the recent methods of PU learning\nrequire an estimate of the class-prior probability in unlabeled data, and it is\nestimated in advance with another method. However, such a two-step approach\nwhich first estimates the class prior and then trains a classifier may not be\nthe optimal approach since the estimation error of the class-prior is not taken\ninto account when a classifier is trained. In this paper, we propose a novel\nunified approach to estimating the class-prior and training a classifier\nalternately. Our proposed method is simple to implement and computationally\nefficient. Through experiments, we demonstrate the practical usefulness of the\nproposed method.\n",
"title": "Alternate Estimation of a Classifier and the Class-Prior from Positive and Unlabeled Data"
} | null | null | null | null | true | null | 1954 | null | Default | null | null |
null | {
"abstract": " We show, in the case of a special dipolar source, that electromagnetic fields\nin fractional quantum mechanics have an unexpected space dependence:\npropagating fields may have non-transverse components, and the distinction\nbetween near-field zone and wave zone is blurred. We employ an extension of\nMaxwell theory, Aharonov-Bohm electrodynamics, which is compatible with\ncurrents $j^\\nu$ conserved globally but not locally, we have derived in another\nwork the field equation $\\partial_\\mu F^{\\mu \\nu}=j^\\nu+i^\\nu$, where $i^\\nu$\nis a non-local function of $j^\\nu$, called \"secondary current\". Y.\\ Wei has\nrecently proved that the probability current in fractional quantum mechanics is\nin general not locally conserved. We compute this current for a Gaussian wave\npacket with fractional parameter $a=3/2$ and find that in a suitable limit it\ncan be approximated by our simplified dipolar source. Currents which are not\nlocally conserved may be present also in other quantum systems whose wave\nfunctions satisfy non-local equations. The combined electromagnetic effects of\nsuch sources and their secondary currents are very interesting both\ntheoretically and for potential applications.\n",
"title": "Oscillating dipole with fractional quantum source in Aharonov-Bohm electrodynamics"
} | null | null | null | null | true | null | 1955 | null | Default | null | null |
null | {
"abstract": " We propose a novel randomized linear programming algorithm for approximating\nthe optimal policy of the discounted Markov decision problem. By leveraging the\nvalue-policy duality and binary-tree data structures, the algorithm adaptively\nsamples state-action-state transitions and makes exponentiated primal-dual\nupdates. We show that it finds an $\\epsilon$-optimal policy using nearly-linear\nrun time in the worst case. When the Markov decision process is ergodic and\nspecified in some special data formats, the algorithm finds an\n$\\epsilon$-optimal policy using run time linear in the total number of\nstate-action pairs, which is sublinear in the input size. These results provide\na new venue and complexity benchmarks for solving stochastic dynamic programs.\n",
"title": "Randomized Linear Programming Solves the Discounted Markov Decision Problem In Nearly-Linear (Sometimes Sublinear) Running Time"
} | null | null | null | null | true | null | 1956 | null | Default | null | null |
null | {
"abstract": " This report summarizes the discussions, open issues, take-away messages, and\nconclusions of the 2nd SCAV workshop.\n",
"title": "SCAV'18: Report of the 2nd International Workshop on Safe Control of Autonomous Vehicles"
} | null | null | [
"Computer Science"
]
| null | true | null | 1957 | null | Validated | null | null |
null | {
"abstract": " Statisticians increasingly face the problem to reconsider the adaptability of\nclassical inference techniques. In particular, divers types of high-dimensional\ndata structures are observed in various research areas; disclosing the\nboundaries of conventional multivariate data analysis. Such situations occur,\ne.g., frequently in life sciences whenever it is easier or cheaper to\nrepeatedly generate a large number $d$ of observations per subject than\nrecruiting many, say $N$, subjects. In this paper we discuss inference\nprocedures for such situations in general heteroscedastic split-plot designs\nwith $a$ independent groups of repeated measurements. These will, e.g., be able\nto answer questions about the occurrence of certain time, group and\ninteractions effects or about particular profiles.\nThe test procedures are based on standardized quadratic forms involving\nsuitably symmetrized U-statistics-type estimators which are robust against an\nincreasing number of dimensions $d$ and/or groups $a$. We then discuss its\nlimit distributions in a general asymptotic framework and additionally propose\nimproved small sample approximations. Finally its small sample performance is\ninvestigated in simulations and the applicability is illustrated by a real data\nanalysis.\n",
"title": "Inference For High-Dimensional Split-Plot-Designs: A Unified Approach for Small to Large Numbers of Factor Levels"
} | null | null | null | null | true | null | 1958 | null | Default | null | null |
null | {
"abstract": " A locally repairable code with availability has the property that every code\nsymbol can be recovered from multiple, disjoint subsets of other symbols of\nsmall size. In particular, a code symbol is said to have $(r,t)$-availability\nif it can be recovered from $t$ disjoint subsets, each of size at most $r$. A\ncode with availability is said to be 'rate-optimal', if its rate is maximum\namong the class of codes with given locality, availability, and alphabet size.\nThis paper focuses on rate-optimal binary, linear codes with small\navailability, and makes four contributions. First, it establishes tight upper\nbounds on the rate of binary linear codes with $(r,2)$ and $(2,3)$\navailability. Second, it establishes a uniqueness result for binary\nrate-optimal codes, showing that for certain classes of binary linear codes\nwith $(r,2)$ and $(2,3)$-availability, any rate optimal code must be a direct\nsum of shorter rate optimal codes. Third, it presents novel upper bounds on the\nrates of binary linear codes with $(2,t)$ and $(r,3)$-availability. In\nparticular, the main contribution here is a new method for bounding the number\nof cosets of the dual of a code with availability, using its covering\nproperties. Finally, it presents a class of locally repairable linear codes\nassociated with convex polyhedra, focusing on the codes associated with the\nPlatonic solids. It demonstrates that these codes are locally repairable with\n$t = 2$, and that the codes associated with (geometric) dual polyhedra are\n(coding theoretic) duals of each other.\n",
"title": "Rate Optimal Binary Linear Locally Repairable Codes with Small Availability"
} | null | null | [
"Computer Science",
"Mathematics"
]
| null | true | null | 1959 | null | Validated | null | null |
null | {
"abstract": " We present a general form of Renormalization operator $\\mathcal{R}$ acting on\npotentials $V:\\{0,1\\}^\\mathbb{N} \\to \\mathbb{R}$. We exhibit the analytical\nexpression of the fixed point potential $V$ for such operator $\\mathcal{R}$.\nThis potential can be expressed in a naturally way in terms of a certain\nintegral over the Hausdorff probability on a Cantor type set on the interval\n$[0,1]$. This result generalizes a previous one by A. Baraviera, R. Leplaideur\nand A. Lopes where the fixed point potential $V$ was of Hofbauer type.\nFor the potentials of Hofbauer type (a well known case of phase transition)\nthe decay is like $n^{-\\gamma}$, $\\gamma>0$.\nAmong other things we present the estimation of the decay of correlation of\nthe equilibrium probability associated to the fixed potential $V$ of our\ngeneral renormalization procedure. In some cases we get polynomial decay like\n$n^{-\\gamma}$, $\\gamma>0$, and in others a decay faster than $n \\,e^{ -\\,\n\\sqrt{n}}$, when $n \\to \\infty$.\nThe potentials $g$ we consider here are elements of the so called family of\nWalters potentials on $\\{0,1\\}^\\mathbb{N} $ which generalizes the potentials\nconsidered initially by F. Hofbauer. For these potentials some explicit\nexpressions for the eigenfunctions are known.\nIn a final section we also show that given any choice $d_n \\to 0$ of real\nnumbers varying with $n \\in \\mathbb{N}$ there exist a potential $g$ on the\nclass defined by Walters which has a invariant probability with such numbers as\nthe coefficients of correlation (for a certain explicit observable function).\n",
"title": "A general renormalization procedure on the one-dimensional lattice and decay of correlations"
} | null | null | null | null | true | null | 1960 | null | Default | null | null |
null | {
"abstract": " We study duality spectral sequences for Weierstrass fibrations. Using these\nspectral sequences, we show that on a K-trivial Weierstrass threefold over a\nK-numerically trivial surface, any line bundle of nonzero fiber degree is taken\nby a Fourier-Mukai transform to a slope stable locally free sheaf.\n",
"title": "Duality Spectral Sequences for Weierstrass Fibrations and Applications"
} | null | null | null | null | true | null | 1961 | null | Default | null | null |
null | {
"abstract": " In this short communication we study a fluid queue with a finite buffer. The\nperformance measure we are interested in is the occupation time over a finite\ntime period, i.e., the fraction of time the workload process is below some\nfixed target level. We construct an alternating sequence of sojourn times\n$D_1,U_1,...$ where the pairs $(D_i,U_i)_{i\\in\\mathbb{N}}$ are i.i.d. random\nvectors. We use this sequence to determine the distribution function of the\noccupation time in terms of its double transform.\n",
"title": "Occupation times for the finite buffer fluid queue with phase-type ON-times"
} | null | null | [
"Mathematics"
]
| null | true | null | 1962 | null | Validated | null | null |
null | {
"abstract": " We introduce the class of affine forward variance (AFV) models of which both\nthe conventional Heston model and the rough Heston model are special cases. We\nshow that AFV models can be characterized by the affine form of their cumulant\ngenerating function, which can be obtained as solution of a convolution Riccati\nequation. We further introduce the class of affine forward order flow intensity\n(AFI) models, which are structurally similar to AFV models, but driven by jump\nprocesses, and which include Hawkes-type models. We show that the cumulant\ngenerating function of an AFI model satisfies a generalized convolution Riccati\nequation and that a high-frequency limit of AFI models converges in\ndistribution to the AFV model.\n",
"title": "Affine forward variance models"
} | null | null | null | null | true | null | 1963 | null | Default | null | null |
null | {
"abstract": " The free loops space $\\Lambda X$ of a space $X$ has become an important\nobject of study particularly in the case when $X$ is a manifold.The study of\nfree loop spaces is motivated in particular by two main examples. The first is\ntheir relation to geometrically distinct periodic geodesics on a manifold,\noriginally studied by Gromoll and Meyer in $1969$. More recently the study of\nstring topology and in particular the Chas-Sullivan loop product has been an\nactive area of research.\nA complete flag manifold is the quotient of a Lie group by its maximal torus\nand is one of the nicer examples of a homogeneous space. Both the cohomology\nand Chas-Sullivan product structure are understood for spaces $S^n$,\n$\\mathbb{C}P^n$ and most simple Lie groups. Hence studying the topology of the\nfree loops space on homogeneous space is a natural next step.\nIn the thesis we compute the differentials in the integral Leray-Serre\nspectral sequence associated to the free loops space fibrations in the cases of\n$SU(n+1)/T^n$ and $Sp(n)/T^n$. Study in detail the structure of the third page\nof the spectral sequence in the case of $SU(n)$ and give the module structure\nof $H^*(\\Lambda(SU(3)/T^2);\\mathbb{Z})$ and\n$H^*(\\Lambda(Sp(2)/T^2);\\mathbb{Z})$.\n",
"title": "The cohomology of free loop spaces of homogeneous spaces"
} | null | null | null | null | true | null | 1964 | null | Default | null | null |
null | {
"abstract": " Cosmic ray muons with the average energy of 280 GeV and neutrons produced by\nmuons are detected with the Large Volume Detector at LNGS. We present an\nanalysis of the seasonal variation of the neutron flux on the basis of the data\nobtained during 15 years. The measurement of the seasonal variation of the\nspecific number of neutrons generated by muons allows to obtaine the variation\nmagnitude of of the average energy of the muon flux at the depth of the LVD\nlocation. The source of the seasonal variation of the total neutron flux is a\nchange of the intensity and the average energy of the muon flux.\n",
"title": "Measurement of the muon-induced neutron seasonal modulation with LVD"
} | null | null | null | null | true | null | 1965 | null | Default | null | null |
null | {
"abstract": " A number of microorganisms leave persistent trails while moving along\nsurfaces. For single-cell organisms, the trail-mediated self-interaction will\ninfluence its dynamics. It has been discussed recently [Kranz \\textit{et al.}\nPhys. Rev. Lett. \\textbf{117}, 8101 (2016)] that the self-interaction may\nlocalize the organism above a critical coupling $\\chi_c$ to the trail. Here we\nwill derive a generalized active particle model capturing the key features of\nthe self-interaction and analyze its behavior for smaller couplings $\\chi <\n\\chi_c$. We find that fluctuations in propulsion speed shift the localization\ntransition to stronger couplings.\n",
"title": "Trail-Mediated Self-Interaction"
} | null | null | null | null | true | null | 1966 | null | Default | null | null |
null | {
"abstract": " In the present paper we study the existence of solutions for some nonlocal\nproblems involving the p(x)-Laplacian operator. The approach is based on a new\nsub-supersolution method\n",
"title": "A sub-super solution method for a class of nonlocal problems involving the p(x)-Laplacian operator and applications"
} | null | null | null | null | true | null | 1967 | null | Default | null | null |
null | {
"abstract": " We show that there exist complete and minimal systems of time-frequency\nshifts of Gaussians in $L^2(\\mathbb{R})$ which are not strong Markushevich\nbasis (do not admit the spectral synthesis). In particular, it implies that\nthere is no linear summation method for general Gaussian Gabor expansions. On\nthe other hand we prove that the spectral synthesis for such Gabor systems\nholds up to one dimensional defect.\n",
"title": "Summability properties of Gabor expansions"
} | null | null | [
"Mathematics"
]
| null | true | null | 1968 | null | Validated | null | null |
null | {
"abstract": " In this paper, we describe a new Las Vegas algorithm to solve the elliptic\ncurve discrete logarithm problem. The algorithm depends on a property of the\ngroup of rational points of an elliptic curve and is thus not a generic\nalgorithm. The algorithm that we describe has some similarities with the most\npowerful index-calculus algorithm for the discrete logarithm problem over a\nfinite field.\n",
"title": "A Las Vegas algorithm to solve the elliptic curve discrete logarithm problem"
} | null | null | null | null | true | null | 1969 | null | Default | null | null |
null | {
"abstract": " These are lecture notes for a short course about spectral sequences that was\nheld at Málaga, October 18--20 (2016), during the \"Fifth Young Spanish\nTopologists Meeting\". The approach was to illustrate the basic notions via\nfully computed examples arising from Algebraic Topology and Group Theory.\n",
"title": "Spectral sequences via examples"
} | null | null | null | null | true | null | 1970 | null | Default | null | null |
null | {
"abstract": " When two identical (coherent) beams are injected at a semi-infinite\nnon-Hermitian medium from left and right, we show that both reflection\n$(r_L,r_R)$ and transmission $(t_L,t_R)$ amplitudes are non-reciprocal. In a\nparametric domain, there exists Spectral Singularity (SS) at a real energy\n$E=E_*$ and the determinant of the time-reversed two port S-matrix i.e.,\n$|\\det(S)|=|t_L t_R-r_L r_R|$ vanishes sharply at $E=E_*$ displaying the\nphenomenon of Coherent Perfect Absorption (CPA). In the complimentary\nparametric domain, the potential becomes either left or right reflectionless at\n$E=E_z$. But we rule out the existence of Invisibility despite $r_R(E_i)=0$ and\n$t_R(E_i)=1$ in these new models. We present two simple exactly solvable models\nwhere the expressions for $E_*$, $E_z$, $E_i$ and the parametric conditions on\nthe potential have been obtained in explicit and simple forms. Earlier, the\nnovel phenomena of SS and CPA have been found to occur only in the scattering\ncomplex potentials which are spatially localized (vanish asymptotically) and\nhaving $t_L=t_R$.\n",
"title": "Coherent scattering from semi-infinite non-Hermitian potentials"
} | null | null | null | null | true | null | 1971 | null | Default | null | null |
null | {
"abstract": " We prove a Structure Identity Principle for theories defined on types of\n$h$-level 3 by defining a general notion of saturation for a large class of\nstructures definable in the Univalent Foundations.\n",
"title": "A Higher Structure Identity Principle"
} | null | null | null | null | true | null | 1972 | null | Default | null | null |
null | {
"abstract": " In recent years, constrained optimization has become increasingly relevant to\nthe machine learning community, with applications including Neyman-Pearson\nclassification, robust optimization, and fair machine learning. A natural\napproach to constrained optimization is to optimize the Lagrangian, but this is\nnot guaranteed to work in the non-convex setting, and, if using a first-order\nmethod, cannot cope with non-differentiable constraints (e.g. constraints on\nrates or proportions).\nThe Lagrangian can be interpreted as a two-player game played between a\nplayer who seeks to optimize over the model parameters, and a player who wishes\nto maximize over the Lagrange multipliers. We propose a non-zero-sum variant of\nthe Lagrangian formulation that can cope with non-differentiable--even\ndiscontinuous--constraints, which we call the \"proxy-Lagrangian\". The first\nplayer minimizes external regret in terms of easy-to-optimize \"proxy\nconstraints\", while the second player enforces the original constraints by\nminimizing swap regret.\nFor this new formulation, as for the Lagrangian in the non-convex setting,\nthe result is a stochastic classifier. For both the proxy-Lagrangian and\nLagrangian formulations, however, we prove that this classifier, instead of\nhaving unbounded size, can be taken to be a distribution over no more than m+1\nmodels (where m is the number of constraints). This is a significant\nimprovement in practical terms.\n",
"title": "Two-Player Games for Efficient Non-Convex Constrained Optimization"
} | null | null | null | null | true | null | 1973 | null | Default | null | null |
null | {
"abstract": " We study how small a local set of the continuum Gaussian free field (GFF) in\ndimension $d$ has to be to ensure that this set is thin, which loosely speaking\nmeans that it captures no GFF mass on itself, in other words, that the field\nrestricted to it is zero. We provide a criterion on the size of the local set\nfor this to happen, and on the other hand, we show that this criterion is sharp\nby constructing small local sets that are not thin.\n",
"title": "On thin local sets of the Gaussian free field"
} | null | null | null | null | true | null | 1974 | null | Default | null | null |
null | {
"abstract": " In a prediction market, individuals can sequentially place bets on the\noutcome of a future event. This leaves a trail of personal probabilities for\nthe event, each being conditional on the current individual's private\nbackground knowledge and on the previously announced probabilities of other\nindividuals, which give partial information about their private knowledge. By\nmeans of theory and examples, we revisit some results in this area. In\nparticular, we consider the case of two individuals, who start with the same\noverall probability distribution but different private information, and then\ntake turns in updating their probabilities. We note convergence of the\nannounced probabilities to a limiting value, which may or may not be the same\nas that based on pooling their private information.\n",
"title": "A Note on Prediction Markets"
} | null | null | null | null | true | null | 1975 | null | Default | null | null |
null | {
"abstract": " Several dihedral angles prediction methods were developed for protein\nstructure prediction and their other applications. However, distribution of\npredicted angles would not be similar to that of real angles. To address this\nwe employed generative adversarial networks (GAN). Generative adversarial\nnetworks are composed of two adversarially trained networks: a discriminator\nand a generator. A discriminator distinguishes samples from a dataset and\ngenerated samples while a generator generates realistic samples. Although the\ndiscriminator of GANs is trained to estimate density, GAN model is intractable.\nOn the other hand, noise-contrastive estimation (NCE) was introduced to\nestimate a normalization constant of an unnormalized statistical model and thus\nthe density function. In this thesis, we introduce noise-contrastive estimation\ngenerative adversarial networks (NCE-GAN) which enables explicit density\nestimation of a GAN model. And a new loss for the generator is proposed. We\nalso propose residue-wise variants of auxiliary classifier GAN (AC-GAN) and\nSemi-supervised GAN to handle sequence information in a window. In our\nexperiment, the conditional generative adversarial network (C-GAN), AC-GAN and\nSemi-supervised GAN were compared. And experiments done with improved\nconditions were invested. We identified a phenomenon of AC-GAN that\ndistribution of its predicted angles is composed of unusual clusters. The\ndistribution of the predicted angles of Semi-supervised GAN was most similar to\nthe Ramachandran plot. We found that adding the output of the NCE as an\nadditional input of the discriminator is helpful to stabilize the training of\nthe GANs and to capture the detailed structures. Adding regression loss and\nusing predicted angles by regression loss only model could improve the\nconditional generation performance of the C-GAN and AC-GAN.\n",
"title": "Dihedral angle prediction using generative adversarial networks"
} | null | null | null | null | true | null | 1976 | null | Default | null | null |
null | {
"abstract": " A simple recurrence relation for the even order moments of the Fabius\nfunction is proven. Also, a very similar formula for the odd order moments in\nterms of the even order moments is proved. The matrices corresponding to these\nformulas (and their inverses) are multiplied so as to obtain a matrix that\ncorrespond to a recurrence relation for the odd order moments in terms of\nthemselves. The theorem at the end gives a closed-form for the coefficients.\n",
"title": "A recurrence relation for the odd order moments of the Fabius function"
} | null | null | null | null | true | null | 1977 | null | Default | null | null |
null | {
"abstract": " A long range corrected range separated hybrid functional is developed based\non the density matrix expansion (DME) based semilocal exchange hole with\nLee-Yang-Parr (LYP) correlation. An extensive study involving the proposed\nrange separated hybrid for thermodynamic as well as properties related to the\nfractional occupation number is compared with different BECKE88 family\nsemilocal, hybrid and range separated hybrids. It has been observed that using\nKohn-Sham kinetic energy dependent exchange hole several properties related to\nthe fractional occupation number can be improved without hindering the\nthermochemical accuracy. The newly constructed range separated hybrid\naccurately describe the hydrogen and non-hydrogen reaction barrier heights. The\npresent range separated functional has been constructed using full semilocal\nmeta-GGA type exchange hole having exact properties related to exchange hole\ntherefore, it has a strong physical basis.\n",
"title": "Performance of Range Separated Hybrids: Study within BECKE88 family and Semilocal Exchange Hole based Range Separated Hybrid"
} | null | null | [
"Physics"
]
| null | true | null | 1978 | null | Validated | null | null |
null | {
"abstract": " Deep networks often perform well on the data distribution on which they are\ntrained, yet give incorrect (and often very confident) answers when evaluated\non points from off of the training distribution. This is exemplified by the\nadversarial examples phenomenon but can also be seen in terms of model\ngeneralization and domain shift. Ideally, a model would assign lower confidence\nto points unlike those from the training distribution. We propose a regularizer\nwhich addresses this issue by training with interpolated hidden states and\nencouraging the classifier to be less confident at these points. Because the\nhidden states are learned, this has an important effect of encouraging the\nhidden states for a class to be concentrated in such a way so that\ninterpolations within the same class or between two different classes do not\nintersect with the real data points from other classes. This has a major\nadvantage in that it avoids the underfitting which can result from\ninterpolating in the input space. We prove that the exact condition for this\nproblem of underfitting to be avoided by Manifold Mixup is that the\ndimensionality of the hidden states exceeds the number of classes, which is\noften the case in practice. Additionally, this concentration can be seen as\nmaking the features in earlier layers more discriminative. We show that despite\nrequiring no significant additional computation, Manifold Mixup achieves large\nimprovements over strong baselines in supervised learning, robustness to\nsingle-step adversarial attacks, semi-supervised learning, and Negative\nLog-Likelihood on held out samples.\n",
"title": "Manifold Mixup: Learning Better Representations by Interpolating Hidden States"
} | null | null | [
"Statistics"
]
| null | true | null | 1979 | null | Validated | null | null |
null | {
"abstract": " In spite of the close connection between the evaluation of quantified Boolean\nformulas (QBF) and propositional satisfiability (SAT), tools and techniques\nwhich exploit structural properties of SAT instances are known to fail for QBF.\nThis is especially true for the structural parameter treewidth, which has\nallowed the design of successful algorithms for SAT but cannot be\nstraightforwardly applied to QBF since it does not take into account the\ninterdependencies between quantified variables.\nIn this work we introduce and develop dependency treewidth, a new structural\nparameter based on treewidth which allows the efficient solution of QBF\ninstances. Dependency treewidth pushes the frontiers of tractability for QBF by\novercoming the limitations of previously introduced variants of treewidth for\nQBF. We augment our results by developing algorithms for computing the\ndecompositions that are required to use the parameter.\n",
"title": "Small Resolution Proofs for QBF using Dependency Treewidth"
} | null | null | null | null | true | null | 1980 | null | Default | null | null |
null | {
"abstract": " The Sagnac effect has been shown in inertial frames as well as rotating\nframes. We solve the problem of the generalized Sagnac effect in the standard\nsynchronization of clocks. The speed of a light beam that traverses an optical\nfiber loop is measured with respect to the proper time of the light detector,\nand is shown to be other than the constant c, though it appears to be c if\nmeasured by the time standard-synchronized. The fiber loop, which can have an\narbitrary shape, is described by an infinite number of straight lines such that\nit can be handled by the general framework of Mansouri and Sexl (MS). For a\ncomplete analysis of the Sagnac effect, the motion of the laboratory should be\ntaken into account. The MS framework is introduced to deal with its motion\nrelative to a preferred reference frame. Though the one-way speed of light is\nother than c, its two-way speed is shown to be c with respect to the proper\ntime. The theoretical analysis of the generalized Sagnac effect corresponds to\nthe experimental results, and shows the usefulness of the standard\nsynchronization. The introduction of the standard synchrony can make\nmathematical manipulation easy and can allow us to deal with relative motions\nbetween inertial frames without information on their velocities relative to the\npreferred frame.\n",
"title": "Theoretical Analysis of Generalized Sagnac Effect in the Standard Synchronization"
} | null | null | [
"Physics"
]
| null | true | null | 1981 | null | Validated | null | null |
null | {
"abstract": " Anisotropic displacement parameters (ADPs) are commonly used in\ncrystallography, chemistry and related fields to describe and quantify thermal\nmotion of atoms. Within the very recent years, these ADPs have become\npredictable by lattice dynamics in combination with first-principles theory.\nHere, we study four very different molecular crystals, namely urea,\nbromomalonic aldehyde, pentachloropyridine, and naphthalene, by\nfirst-principles theory to assess the quality of ADPs calculated in the\nquasi-harmonic approximation. In addition, we predict both thermal expansion\nand thermal motion within the quasi-harmonic approximation and compare the\npredictions with experimental data. Very reliable ADPs are calculated within\nthe quasi-harmonic approximation for all four cases up to at least 200 K, and\nthey turn out to be in better agreement with experiment than the harmonic ones.\nIn one particular case, ADPs can even reliably be predicted up to room\ntemperature. Our results also hint at the importance of normal-mode\nanharmonicity in the calculation of ADPs.\n",
"title": "Lattice thermal expansion and anisotropic displacements in urea, bromomalonic aldehyde, pentachloropyridine and naphthalene"
} | null | null | null | null | true | null | 1982 | null | Default | null | null |
null | {
"abstract": " Robotic motion planning problems are typically solved by constructing a\nsearch tree of valid maneuvers from a start to a goal configuration. Limited\nonboard computation and real-time planning constraints impose a limit on how\nlarge this search tree can grow. Heuristics play a crucial role in such\nsituations by guiding the search towards potentially good directions and\nconsequently minimizing search effort. Moreover, it must infer such directions\nin an efficient manner using only the information uncovered by the search up\nuntil that time. However, state of the art methods do not address the problem\nof computing a heuristic that explicitly minimizes search effort. In this\npaper, we do so by training a heuristic policy that maps the partial\ninformation from the search to decide which node of the search tree to expand.\nUnfortunately, naively training such policies leads to slow convergence and\npoor local minima. We present SaIL, an efficient algorithm that trains\nheuristic policies by imitating \"clairvoyant oracles\" - oracles that have full\ninformation about the world and demonstrate decisions that minimize search\neffort. We leverage the fact that such oracles can be efficiently computed\nusing dynamic programming and derive performance guarantees for the learnt\nheuristic. We validate the approach on a spectrum of environments which show\nthat SaIL consistently outperforms state of the art algorithms. Our approach\npaves the way forward for learning heuristics that demonstrate an anytime\nnature - finding feasible solutions quickly and incrementally refining it over\ntime.\n",
"title": "Learning Heuristic Search via Imitation"
} | null | null | null | null | true | null | 1983 | null | Default | null | null |
null | {
"abstract": " In this article we consider hook removal operators on odd partitions, i.e.,\npartitions labelling odd-degree irreducible characters of finite symmetric\ngroups. In particular we complete the discussion, started by Isaacs, Navarro,\nOlsson and Tiep in 2016, concerning the commutativity of such operators.\n",
"title": "Hook removal operators on the odd Young graph"
} | null | null | null | null | true | null | 1984 | null | Default | null | null |
null | {
"abstract": " In the present paper we consider modal propositional logic and look for the\nconstraints that are imposed to the propositions of the special type $\\Box a$\nby the structure of the relevant finite Kripke frame. We translate the usual\nlanguage of modal propositional logic in terms of notions of commutative\nalgebra, namely polynomial rings, ideals, and bases of ideals. We use\nextensively the perspective obtained in previous works in Algebraic Statistics.\nWe prove that the constraints on $\\Box a$ can be derived through a binomial\nideal containing a toric ideal and we give sufficient conditions under which\nthe toric ideal fully describes the constraints.\n",
"title": "Modal operators and toric ideals"
} | null | null | null | null | true | null | 1985 | null | Default | null | null |
null | {
"abstract": " Neural network (NN) model chemistries (MCs) promise to facilitate the\naccurate exploration of chemical space and simulation of large reactive\nsystems. One important path to improving these models is to add layers of\nphysical detail, especially long-range forces. At short range, however, these\nmodels are data driven and data limited. Little is systematically known about\nhow data should be sampled, and `test data' chosen randomly from some sampling\ntechniques can provide poor information about generality. If the sampling\nmethod is narrow `test error' can appear encouragingly tiny while the model\nfails catastrophically elsewhere. In this manuscript we competitively evaluate\ntwo common sampling methods: molecular dynamics (MD), normal-mode sampling\n(NMS) and one uncommon alternative, Metadynamics (MetaMD), for preparing\ntraining geometries. We show that MD is an inefficient sampling method in the\nsense that additional samples do not improve generality. We also show MetaMD is\neasily implemented in any NNMC software package with cost that scales linearly\nwith the number of atoms in a sample molecule. MetaMD is a black-box way to\nensure samples always reach out to new regions of chemical space, while\nremaining relevant to chemistry near $k_bT$. It is one cheap tool to address\nthe issue of generalization.\n",
"title": "Metadynamics for Training Neural Network Model Chemistries: a Competitive Assessment"
} | null | null | null | null | true | null | 1986 | null | Default | null | null |
null | {
"abstract": " Automated service classification plays a crucial role in service management\nsuch as service discovery, selection, and composition. In recent years, machine\nlearning techniques have been used for service classification. However, they\ncan only predict around 10 to 20 service categories due to the quality of\nfeature engineering and the imbalance problem of service dataset. In this\npaper, we present a deep neural network ServeNet with a novel dataset splitting\nalgorithm to deal with these issues. ServeNet can automatically abstract\nlow-level representation to high-level features, and then predict service\nclassification based on the service datasets produced by the proposed splitting\nalgorithm. To demonstrate the effectiveness of our approach, we conducted a\ncomprehensive experimental study on 10,000 real-world services in 50\ncategories. The result shows that ServeNet can achieve higher accuracy than\nother machine learning methods.\n",
"title": "ServeNet: A Deep Neural Network for Web Service Classification"
} | null | null | null | null | true | null | 1987 | null | Default | null | null |
null | {
"abstract": " We study the photoinduced breakdown of a two-orbital Mott insulator and\nresulting metallic state. Using time-dependent density matrix renormalization\ngroup, we scrutinize the real-time dynamics of the half-filled two-orbital\nHubbard model interacting with a resonant radiation field pulse. The breakdown,\ncaused by production of doublon-holon pairs, is enhanced by Hund's exchange,\nwhich dynamically activates large orbital fluctuations. The melting of the Mott\ninsulator is accompanied by a high to low spin transition with a concomitant\nreduction of antiferromagnetic spin fluctuations. Most notably, the overall\ntime response is driven by the photogeneration of excitons with orbital\ncharacter that are stabilized by Hund's coupling. These unconventional \"Hund\nexcitons\" correspond to bound spin-singlet orbital-triplet doublon-holon pairs.\nWe study exciton properties such as bandwidth, binding potential, and size\nwithin a semiclassical approach. The photometallic state results from a\ncoexistence of Hund excitons and doublon-holon plasma.\n",
"title": "Photoinduced Hund excitons in the breakdown of a two-orbital Mott insulator"
} | null | null | null | null | true | null | 1988 | null | Default | null | null |
null | {
"abstract": " We draw a formal connection between using synthetic training data to optimize\nneural network parameters and approximate, Bayesian, model-based reasoning. In\nparticular, training a neural network using synthetic data can be viewed as\nlearning a proposal distribution generator for approximate inference in the\nsynthetic-data generative model. We demonstrate this connection in a\nrecognition task where we develop a novel Captcha-breaking architecture and\ntrain it using synthetic data, demonstrating both state-of-the-art performance\nand a way of computing task-specific posterior uncertainty. Using a neural\nnetwork trained this way, we also demonstrate successful breaking of real-world\nCaptchas currently used by Facebook and Wikipedia. Reasoning from these\nempirical results and drawing connections with Bayesian modeling, we discuss\nthe robustness of synthetic data results and suggest important considerations\nfor ensuring good neural network generalization when training with synthetic\ndata.\n",
"title": "Using Synthetic Data to Train Neural Networks is Model-Based Reasoning"
} | null | null | null | null | true | null | 1989 | null | Default | null | null |
null | {
"abstract": " Learning and memory are intertwined in our brain and their relationship is at\nthe core of several recent neural network models. In particular, the\nAttention-Gated MEmory Tagging model (AuGMEnT) is a reinforcement learning\nnetwork with an emphasis on biological plausibility of memory dynamics and\nlearning. We find that the AuGMEnT network does not solve some hierarchical\ntasks, where higher-level stimuli have to be maintained over a long time, while\nlower-level stimuli need to be remembered and forgotten over a shorter\ntimescale. To overcome this limitation, we introduce hybrid AuGMEnT, with leaky\nor short-timescale and non-leaky or long-timescale units in memory, that allow\nto exchange lower-level information while maintaining higher-level one, thus\nsolving both hierarchical and distractor tasks.\n",
"title": "Multi-timescale memory dynamics in a reinforcement learning network with attention-gated memory"
} | null | null | null | null | true | null | 1990 | null | Default | null | null |
null | {
"abstract": " The non-linear response of entangled polymers to shear flow is complicated.\nIts current understanding is framed mainly as a rheological description in\nterms of the complex viscosity. However, the full picture requires an\nassessment of the dynamical structure of individual polymer chains which give\nrise to the macroscopic observables. Here we shed new light on this problem,\nusing a computer simulation based on a blob model, extended to describe shear\nflow in polymer melts and semi-dilute solutions. We examine the diffusion and\nthe intermediate scattering spectra during a steady shear flow. The relaxation\ndynamics are found to speed up along the flow direction, but slow down along\nthe shear gradient direction. The third axis, vorticity, shows a slowdown at\nthe short scale of a tube, but reaches a net speedup at the large scale of the\nchain radius of gyration.\n",
"title": "Dynamical structure of entangled polymers simulated under shear flow"
} | null | null | null | null | true | null | 1991 | null | Default | null | null |
null | {
"abstract": " We demonstrate the generation of higher-order modulation formats using\nsilicon-based inphase/quadrature (IQ) modulators at symbol rates of up to 100\nGBd. Our devices exploit the advantages of silicon-organic hybrid (SOH)\nintegration, which combines silicon-on-insulator waveguides with highly\nefficient organic electro-optic (EO) cladding materials to enable small drive\nvoltages and sub-millimeter device lengths. In our experiments, we use an SOH\nIQ modulator with a {\\pi}-voltage of 1.6 V to generate 100 GBd 16QAM signals.\nThis is the first time that the 100 GBd mark is reached with an IQ modulator\nrealized on a semiconductor substrate, leading to a single-polarization line\nrate of 400 Gbit/s. The peak-to-peak drive voltages amount to 1.5 Vpp,\ncorresponding to an electrical energy dissipation in the modulator of only 25\nfJ/bit.\n",
"title": "Coherent modulation up to 100 GBd 16QAM using silicon-organic hybrid (SOH) devices"
} | null | null | null | null | true | null | 1992 | null | Default | null | null |
null | {
"abstract": " Magnetic trilayers having large perpendicular magnetic anisotropy (PMA) and\nhigh spin-orbit torques (SOTs) efficiency are the key to fabricate nonvolatile\nmagnetic memory and logic devices. In this work, PMA and SOTs are\nsystematically studied in Pt/Co/Cr stacks as a function of Cr thickness. An\nenhanced perpendicular anisotropy field around 10189 Oe is obtained and is\nrelated to the interface between Co and Cr layers. In addition, an effective\nspin Hall angle up to 0.19 is observed due to the improved antidamping-like\ntorque by employing dissimilar metals Pt and Cr with opposite signs of spin\nHall angles on opposite sides of Co layer. Finally, we observed a nearly linear\ndependence between spin Hall angle and longitudinal resistivity from their\ntemperature dependent properties, suggesting that the spin Hall effect may\narise from extrinsic skew scattering mechanism. Our results indicate that 3d\ntransition metal Cr with a large negative spin Hall angle could be used to\nengineer the interfaces of trilayers to enhance PMA and SOTs.\n",
"title": "Current induced magnetization switching in PtCoCr structures with enhanced perpendicular magnetic anisotropy and spin-orbit torques"
} | null | null | null | null | true | null | 1993 | null | Default | null | null |
null | {
"abstract": " Grain boundary diffusion in severely deformed Al-based AA5024 alloy is\ninvestigated. Different states are prepared by combination of equal channel\nangular processing and heat treatments, with the radioisotope $^{57}$Co being\nemployed as a sensitive probe of a given grain boundary state. Its diffusion\nrates near room temperature (320~K) are utilized to quantify the effects of\nsevere plastic deformation and a presumed formation of a previously reported\ndeformation-modified state of grain boundaries, solute segregation at the\ninterfaces, increased dislocation content after deformation and of the\nprecipitation behavior on the transport phenomena along grain boundaries. The\ndominant effect of nano-sized Al$_3$Sc-based precipitates is evaluated using\ndensity functional theory and the Eshelby model for the determination of\nelastic stresses around the precipitates.\n",
"title": "Grain boundary diffusion in severely deformed Al-based alloy"
} | null | null | [
"Physics"
]
| null | true | null | 1994 | null | Validated | null | null |
null | {
"abstract": " The quantum Schrodinger-Newton equation is solved for a self-gravitating Bose\ngas at zero temperature. It is derived that the density is non-uniform and a\ncentral hollow cavity exists. The radial distribution of the particle momentum\nis uniform. It is shown that a quantum black hole can be formed only above a\ncertain critical mass. The temperature effect is accounted for via the\nSchrodinger-Poisson-Boltzmann equation, where low and high temperature\nsolutions are obtained. The theoretical analysis is extended to a strong\ninteracting gas via the Schrodinger-Yukawa equation, showing that the atomic\nnuclei are also hollow. Hollow self-gravitating Fermi gases are described by\nthe Thomas-Fermi equation.\n",
"title": "Quantum Black Holes and Atomic Nuclei are Hollow"
} | null | null | null | null | true | null | 1995 | null | Default | null | null |
null | {
"abstract": " We consider learning a predictor which is non-discriminatory with respect to\na \"protected attribute\" according to the notion of \"equalized odds\" proposed by\nHardt et al. [2016]. We study the problem of learning such a non-discriminatory\npredictor from a finite training set, both statistically and computationally.\nWe show that a post-hoc correction approach, as suggested by Hardt et al, can\nbe highly suboptimal, present a nearly-optimal statistical procedure, argue\nthat the associated computational problem is intractable, and suggest a second\nmoment relaxation of the non-discrimination definition for which learning is\ntractable.\n",
"title": "Learning Non-Discriminatory Predictors"
} | null | null | null | null | true | null | 1996 | null | Default | null | null |
null | {
"abstract": " Many brown dwarfs exhibit photometric variability at levels from tenths to\ntens of percents. The photometric variability is related to magnetic activity\nor patchy cloud coverage, characteristic of brown dwarfs near the L-T\ntransition. Time-resolved spectral monitoring of brown dwarfs provides\ndiagnostics of cloud distribution and condensate properties. However, current\ntime-resolved spectral studies of brown dwarfs are limited to low spectral\nresolution (R$\\sim$100) with the exception of the study of Luhman 16 AB at\nresolution of 100,000 using the VLT$+$CRIRES. This work yielded the first map\nof brown dwarf surface inhomogeneity, highlighting the importance and unique\ncontribution of high spectral resolution observations. Here, we report on the\ntime-resolved high spectral resolution observations of a nearby brown dwarf\nbinary, 2MASSW J0746425+200032AB. We find no coherent spectral variability that\nis modulated with rotation. Based on simulations we conclude that the coverage\nof a single spot on 2MASSW J0746425+200032AB is smaller than 1\\% or 6.25\\% if\nspot contrast is 50\\% or 80\\% of its surrounding flux, respectively. Future\nhigh spectral resolution observations aided by adaptive optics systems can put\ntighter constraints on the spectral variability of 2MASSW J0746425+200032AB and\nother nearby brown dwarfs.\n",
"title": "Time-Resolved High Spectral Resolution Observation of 2MASSW J0746425+200032AB"
} | null | null | null | null | true | null | 1997 | null | Default | null | null |
null | {
"abstract": " Traveling fronts describe the transition between two alternative states in a\ngreat number of physical and biological systems. Examples include the spread of\nbeneficial mutations, chemical reactions, and the invasions by foreign species.\nIn homogeneous environments, the alternative states are separated by a smooth\nfront moving at a constant velocity. This simple picture can break down in\nstructured environments such as tissues, patchy landscapes, and microfluidic\ndevices. Habitat fragmentation can pin the front at a particular location or\nlock invasion velocities into specific values. Locked velocities are not\nsensitive to moderate changes in dispersal or growth and are determined by the\nspatial and temporal periodicity of the environment. The synchronization with\nthe environment results in discontinuous fronts that propagate as periodic\npulses. We characterize the transition from continuous to locked invasions and\nshow that it is controlled by positive density-dependence in dispersal or\ngrowth. We also demonstrate that velocity locking is robust to demographic and\nenvironmental fluctuations and examine stochastic dynamics and evolution in\nlocked invasions.\n",
"title": "Pinned, locked, pushed, and pulled traveling waves in structured environments"
} | null | null | null | null | true | null | 1998 | null | Default | null | null |
null | {
"abstract": " We propose an original concept of compressive sensing (CS) polarimetric\nimaging based on a digital micro-mirror (DMD) array and two single-pixel\ndetectors. The polarimetric sensitivity of the proposed setup is due to an\nexperimental imperfection of reflecting mirrors which is exploited here to form\nan original reconstruction problem, including a CS problem and a source\nseparation task. We show that a two-step approach tackling each problem\nsuccessively is outperformed by a dedicated combined reconstruction method,\nwhich is explicited in this article and preferably implemented through a\nreweighted FISTA algorithm. The combined reconstruction approach is then\nfurther improved by including physical constraints specific to the polarimetric\nimaging context considered, which are implemented in an original constrained\nGFB algorithm. Numerical simulations demonstrate the efficiency of the 2-pixel\nCS polarimetric imaging setup to retrieve polarimetric contrast data with\nsignificant compression rate and good reconstruction quality. The influence of\nexperimental imperfections of the DMD are also analyzed through numerical\nsimulations, and 2D polarimetric imaging reconstruction results are finally\npresented.\n",
"title": "Two-pixel polarimetric camera by compressive sensing"
} | null | null | null | null | true | null | 1999 | null | Default | null | null |
null | {
"abstract": " Advantages of electric vehicles (EV) include reduction of greenhouse gas and\nother emissions, energy security, and fuel economy. The societal benefits of\nlarge-scale adoption of EVs cannot be realized without adequate deployment of\npublicly accessible charging stations. We propose a two-stage stochastic\nprogramming model to determine the optimal network of charging stations for a\ncommunity considering uncertainties in arrival and dwell time of vehicles,\nbattery state of charge of arriving vehicles, walkable range and charging\npreferences of drivers, demand during weekdays and weekends, and rate of\nadoption of EVs within a community. We conducted studies using sample average\napproximation (SAA) method which asymptotically converges to an optimal\nsolution for a two-stage stochastic problem, however it is computationally\nexpensive for large-scale instances. Therefore, we developed a heuristic to\nproduce near to optimal solutions quickly for our data instances. We conducted\ncomputational experiments using various publicly available data sources, and\nbenefits of the solutions are evaluated both quantitatively and qualitatively\nfor a given community.\n",
"title": "A Stochastic Programming Approach for Electric Vehicle Charging Network Design"
} | null | null | null | null | true | null | 2000 | null | Default | null | null |
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