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null | {
"abstract": " This paper introduces a class of backward stochastic differential equations\n(BSDEs), whose coefficients not only depend on the value of its solutions of\nthe present but also the past and the future. For a sufficiently small time\ndelay or a sufficiently small Lipschitz constant, the existence and uniqueness\nof such BSDEs is obtained. As an adjoint process, a class of stochastic\ndifferential equations (SDEs) is introduced, whose coefficients also depend on\nthe present, the past and the future of its solutions. The existence and\nuniqueness of such SDEs is proved for a sufficiently small time advance or a\nsufficiently small Lipschitz constant. A duality between such BSDEs and SDEs is\nestablished.\n",
"title": "BSDEs and SDEs with time-advanced and -delayed coefficients"
} | null | null | null | null | true | null | 18201 | null | Default | null | null |
null | {
"abstract": " In this paper we present a thorough analysis of the nature of news in\ndifferent mediums across the ages, introducing a unique mathematical model to\nfit the characteristics of information spread. This model enhances the\ninformation diffusion model to account for conflicting information and the\ntopical distribution of news in terms of popularity for a given era. We\ntranslate this information to a separate graphical node model to determine the\nspread of a news item given a certain category and relevance factor. The two\nmodels are used as a base for a simulation of information dissemination for\nvarying graph topoligies. The simulation is stress-tested and compared against\nreal-world data to prove its relevancy. We are then able to use these\nsimulations to deduce some conclusive statements about the optimization of\ninformation spread.\n",
"title": "Characterizing information importance and the effect on the spread in various graph topologies"
} | null | null | null | null | true | null | 18202 | null | Default | null | null |
null | {
"abstract": " The superconductor-insulator transition (SIT) is considered an excellent\nexample of a quantum phase transition which is driven by quantum fluctuations\nat zero temperature. The quantum critical point is characterized by a diverging\ncorrelation length and a vanishing energy scale. Low energy fluctuations near\nquantum criticality may be experimentally detected by specific heat, $c_{\\rm\np}$, measurements. Here, we use a unique highly sensitive experiment to measure\n$c_{\\rm p}$ of two-dimensional granular Pb films through the SIT. The specific\nheat shows the usual jump at the mean field superconducting transition\ntemperature $T_{\\rm c}^{\\rm {mf}}$ marking the onset of Cooper pairs formation.\nAs the film thickness is tuned toward the SIT, $T_{\\rm c}^{\\rm {mf}}$ is\nrelatively unchanged, while the magnitude of the jump and low temperature\nspecific heat increase significantly. This behaviour is taken as the\nthermodynamic fingerprint of quantum criticality in the vicinity of a quantum\nphase transition.\n",
"title": "Quantum criticality at the superconductor to insulator transition revealed by specific heat measurements"
} | null | null | null | null | true | null | 18203 | null | Default | null | null |
null | {
"abstract": " We introduce a novel formulation of motion planning, for continuous-time\ntrajectories, as probabilistic inference. We first show how smooth\ncontinuous-time trajectories can be represented by a small number of states\nusing sparse Gaussian process (GP) models. We next develop an efficient\ngradient-based optimization algorithm that exploits this sparsity and GP\ninterpolation. We call this algorithm the Gaussian Process Motion Planner\n(GPMP). We then detail how motion planning problems can be formulated as\nprobabilistic inference on a factor graph. This forms the basis for GPMP2, a\nvery efficient algorithm that combines GP representations of trajectories with\nfast, structure-exploiting inference via numerical optimization. Finally, we\nextend GPMP2 to an incremental algorithm, iGPMP2, that can efficiently replan\nwhen conditions change. We benchmark our algorithms against several\nsampling-based and trajectory optimization-based motion planning algorithms on\nplanning problems in multiple environments. Our evaluation reveals that GPMP2\nis several times faster than previous algorithms while retaining robustness. We\nalso benchmark iGPMP2 on replanning problems, and show that it can find\nsuccessful solutions in a fraction of the time required by GPMP2 to replan from\nscratch.\n",
"title": "Continuous-Time Gaussian Process Motion Planning via Probabilistic Inference"
} | null | null | [
"Computer Science"
]
| null | true | null | 18204 | null | Validated | null | null |
null | {
"abstract": " The injective polynomial modules for a general linear group $G$ of degree $n$\nare labelled by the partitions with at most $n$ parts. Working over an\nalgebraically closed field of characteristic $p$, we consider the question of\nwhich partitions correspond to polynomially injective modules that are also\ninjective as modules for the restricted enveloping algebra of the Lie algebra\nof $G$. The question is related to the \"index of divisibility\" of a polynomial\nmodule in general, and an explicit answer is given for $n=2$.\n",
"title": "Polynomially and Infinitesimally Injective Modules"
} | null | null | null | null | true | null | 18205 | null | Default | null | null |
null | {
"abstract": " The goal of this present manuscript is to introduce the reader to the\nnonstandard method and to provide an overview of its most prominent\napplications in Ramsey theory and combinatorial number theory.\n",
"title": "Nonstandard Methods in Ramsey Theory and Combinatorial Number Theory"
} | null | null | null | null | true | null | 18206 | null | Default | null | null |
null | {
"abstract": " The \"least absolute shrinkage and selection operator\" (Lasso) method has been\nadapted recently for networkstructured datasets. In particular, this network\nLasso method allows to learn graph signals from a small number of noisy signal\nsamples by using the total variation of a graph signal for regularization.\nWhile efficient and scalable implementations of the network Lasso are\navailable, only little is known about the conditions on the underlying network\nstructure which ensure network Lasso to be accurate. By leveraging concepts of\ncompressed sensing, we address this gap and derive precise conditions on the\nunderlying network topology and sampling set which guarantee the network Lasso\nfor a particular loss function to deliver an accurate estimate of the entire\nunderlying graph signal. We also quantify the error incurred by network Lasso\nin terms of two constants which reflect the connectivity of the sampled nodes.\n",
"title": "When is Network Lasso Accurate?"
} | null | null | null | null | true | null | 18207 | null | Default | null | null |
null | {
"abstract": " Wireless sensor networks are deployed in many monitoring applications but\nstill suffer from short lifetimes originating from limited energy sources and\nstorages. Due to their low-power consumption and their on-demand communication\nability, wake-up receivers represent an energy efficient and simple enhancement\nto wireless sensor nodes and wireless sensor network protocols. In this\ncontext, wake-up receivers have the ability to increase the network lifetime.\nIn this article, we present T-ROME, a simple and energy efficient cross-layer\nrouting protocol for wireless sensor nodes containing wake-up receivers. The\nprotocol makes use of the different transmission ranges of wake-up and main\nradios in order to save energy by skipping nodes during data transfer. With\nrespect to energy consumption and latency, T-ROME outperforms existing\nprotocols in many scenarios. Here, we describe and analyze the cross layer\nmulti-hop protocol by means of a Markov chain model that we verify using a\nlaboratory test setup.\n",
"title": "T-ROME: A Simple and Energy Efficient Tree Routing Protocol for Low-Power Wake-up Receivers"
} | null | null | null | null | true | null | 18208 | null | Default | null | null |
null | {
"abstract": " White-box test generator tools rely only on the code under test to select\ntest inputs, and capture the implementation's output as assertions. If there is\na fault in the implementation, it could get encoded in the generated tests.\nTool evaluations usually measure fault-detection capability using the number of\nsuch fault-encoding tests. However, these faults are only detected, if the\ndeveloper can recognize that the encoded behavior is faulty. We designed an\nexploratory study to investigate how developers perform in classifying\ngenerated white-box test as faulty or correct. We carried out the study in a\nlaboratory setting with 54 graduate students. The tests were generated for two\nopen-source projects with the help of the IntelliTest tool. The performance of\nthe participants were analyzed using binary classification metrics and by\ncoding their observed activities. The results showed that participants\nincorrectly classified a large number of both fault-encoding and correct tests\n(with median misclassification rate 33% and 25% respectively). Thus the real\nfault-detection capability of test generators could be much lower than\ntypically reported, and we suggest to take this human factor into account when\nevaluating generated white-box tests.\n",
"title": "Classifying the Correctness of Generated White-Box Tests: An Exploratory Study"
} | null | null | null | null | true | null | 18209 | null | Default | null | null |
null | {
"abstract": " We study the B ring's complex optical depth structure. The source of this\nstructure may be the complex dynamics of the Keplerian shear and the\nself-gravity of the ring particles. The outcome of these dynamic effects\ndepends sensitively on the collisional and physical properties of the\nparticles. Two mechanisms can emerge that dominate the macroscopic physical\nstructure of the ring: self-gravity wakes and viscous overstability. Here we\nstudy the interplay between these two mechanisms by using our recently\ndeveloped particle collision method that allows us to better model the\ninter-particle contact physics. We find that for a constant ring surface\ndensity and particle internal density, particles with rough surfaces tend to\nproduce axisymmetric ring features associated with the viscous overstability,\nwhile particles with smoother surfaces produce self-gravity wakes.\n",
"title": "Numerical Simulations of Saturn's B Ring: Granular Friction as a Mediator between Self-Gravity and Viscous Overstability"
} | null | null | null | null | true | null | 18210 | null | Default | null | null |
null | {
"abstract": " We determined the shock-darkening pressure range in ordinary chondrites using\nthe iSALE shock physics code. We simulated planar shock waves on a mesoscale in\na sample layer at different nominal pressures. Iron and troilite grains were\nresolved in a porous olivine matrix in the sample layer. We used equations of\nstate (Tillotson EoS and ANEOS) and basic strength and thermal properties to\ndescribe the material phases. We used Lagrangian tracers to record peak shock\npressures in each material unit. The post-shock temperatures (and the fractions\nof tracers experiencing temperatures above the melting point) for each material\nwere estimated after the passage of the shock wave and after reflections of the\nshock at grain boundaries in the heterogeneous materials. The results showed\nthat shock-darkening, associated with troilite melt and the onset of olivine\nmelt, happened between 40 and 50 GPa - with 52 GPa being the pressure at which\nall tracers in the troilite material reach the melting point. We demonstrate\nthe difficulties of shock heating in iron and also the importance of porosity.\nMaterial impedances, grain shapes and the porosity models available in the\niSALE code are discussed. We also discussed possible not-shock-related triggers\nfor iron melt.\n",
"title": "Shock-darkening in ordinary chondrites: determination of the pressure-temperature conditions by shock physics mesoscale modeling"
} | null | null | null | null | true | null | 18211 | null | Default | null | null |
null | {
"abstract": " In this paper we study the global fluctuations of block Gaussian matrices\nwithin the framework of second-order free probability theory. In order to\ncompute the second-order Cauchy transform of these matrices, we introduce a\nmatricial second-order conditional expectation and compute the matricial\nsecond-order Cauchy transform of a certain type of non-commutative random\nvariables. As a by-product, using the linearization technique, we obtain the\nsecond-order Cauchy transform of non-commutative rational functions evaluated\non selfadjoint Gaussian matrices.\n",
"title": "On the Global Fluctuations of Block Gaussian Matrices"
} | null | null | null | null | true | null | 18212 | null | Default | null | null |
null | {
"abstract": " This paper analyzes publication efficiency in terms of Hirsch-index or\nh-index and total citations, with an analogy to the Carnot efficiency used in\nthermodynamics. Such publication efficiency, with typical value of 30%, can be\nutilized to normalize the research output judgment, favoring quality outputs in\nreduced quantity, which is currently lacking in many discipline.\n",
"title": "Carnot Efficiency of Publication"
} | null | null | [
"Computer Science"
]
| null | true | null | 18213 | null | Validated | null | null |
null | {
"abstract": " Event-based cameras have shown great promise in a variety of situations where\nframe based cameras suffer, such as high speed motions and high dynamic range\nscenes. However, developing algorithms for event measurements requires a new\nclass of hand crafted algorithms. Deep learning has shown great success in\nproviding model free solutions to many problems in the vision community, but\nexisting networks have been developed with frame based images in mind, and\nthere does not exist the wealth of labeled data for events as there does for\nimages for supervised training. To these points, we present EV-FlowNet, a novel\nself-supervised deep learning pipeline for optical flow estimation for event\nbased cameras. In particular, we introduce an image based representation of a\ngiven event stream, which is fed into a self-supervised neural network as the\nsole input. The corresponding grayscale images captured from the same camera at\nthe same time as the events are then used as a supervisory signal to provide a\nloss function at training time, given the estimated flow from the network. We\nshow that the resulting network is able to accurately predict optical flow from\nevents only in a variety of different scenes, with performance competitive to\nimage based networks. This method not only allows for accurate estimation of\ndense optical flow, but also provides a framework for the transfer of other\nself-supervised methods to the event-based domain.\n",
"title": "EV-FlowNet: Self-Supervised Optical Flow Estimation for Event-based Cameras"
} | null | null | null | null | true | null | 18214 | null | Default | null | null |
null | {
"abstract": " Deep learning has yielded state-of-the-art performance on many natural\nlanguage processing tasks including named entity recognition (NER). However,\nthis typically requires large amounts of labeled data. In this work, we\ndemonstrate that the amount of labeled training data can be drastically reduced\nwhen deep learning is combined with active learning. While active learning is\nsample-efficient, it can be computationally expensive since it requires\niterative retraining. To speed this up, we introduce a lightweight architecture\nfor NER, viz., the CNN-CNN-LSTM model consisting of convolutional character and\nword encoders and a long short term memory (LSTM) tag decoder. The model\nachieves nearly state-of-the-art performance on standard datasets for the task\nwhile being computationally much more efficient than best performing models. We\ncarry out incremental active learning, during the training process, and are\nable to nearly match state-of-the-art performance with just 25\\% of the\noriginal training data.\n",
"title": "Deep Active Learning for Named Entity Recognition"
} | null | null | null | null | true | null | 18215 | null | Default | null | null |
null | {
"abstract": " Many methods exist for a bipedal robot to keep its balance while walking. In\naddition to step size and timing, other strategies are possible that influence\nthe stability of the robot without interfering with the target direction and\nspeed of locomotion. This paper introduces a multifaceted feedback controller\nthat uses numerous different feedback mechanisms, collectively termed\ncorrective actions, to stabilise a core keypoint-based gait. The feedback\ncontroller is experimentally effective, yet free of any physical model of the\nrobot, very computationally inexpensive, and requires only a single 6-axis IMU\nsensor. Due to these low requirements, the approach is deemed to be highly\nportable between robots, and was specifically also designed to target lower\ncost robots that have suboptimal sensing, actuation and computational\nresources. The IMU data is used to estimate the yaw-independent tilt\norientation of the robot, expressed in the so-called tilt phase space, and is\nthe source of all feedback provided by the controller. Experimental validation\nis performed in simulation as well as on real robot hardware.\n",
"title": "Bipedal Walking with Corrective Actions in the Tilt Phase Space"
} | null | null | null | null | true | null | 18216 | null | Default | null | null |
null | {
"abstract": " Inspired by the tremendous success of deep Convolutional Neural Networks as\ngeneric feature extractors for images, we propose TimeNet: a deep recurrent\nneural network (RNN) trained on diverse time series in an unsupervised manner\nusing sequence to sequence (seq2seq) models to extract features from time\nseries. Rather than relying on data from the problem domain, TimeNet attempts\nto generalize time series representation across domains by ingesting time\nseries from several domains simultaneously. Once trained, TimeNet can be used\nas a generic off-the-shelf feature extractor for time series. The\nrepresentations or embeddings given by a pre-trained TimeNet are found to be\nuseful for time series classification (TSC). For several publicly available\ndatasets from UCR TSC Archive and an industrial telematics sensor data from\nvehicles, we observe that a classifier learned over the TimeNet embeddings\nyields significantly better performance compared to (i) a classifier learned\nover the embeddings given by a domain-specific RNN, as well as (ii) a nearest\nneighbor classifier based on Dynamic Time Warping.\n",
"title": "TimeNet: Pre-trained deep recurrent neural network for time series classification"
} | null | null | null | null | true | null | 18217 | null | Default | null | null |
null | {
"abstract": " Federated learning is a recent advance in privacy protection. In this\ncontext, a trusted curator aggregates parameters optimized in decentralized\nfashion by multiple clients. The resulting model is then distributed back to\nall clients, ultimately converging to a joint representative model without\nexplicitly having to share the data. However, the protocol is vulnerable to\ndifferential attacks, which could originate from any party contributing during\nfederated optimization. In such an attack, a client's contribution during\ntraining and information about their data set is revealed through analyzing the\ndistributed model. We tackle this problem and propose an algorithm for client\nsided differential privacy preserving federated optimization. The aim is to\nhide clients' contributions during training, balancing the trade-off between\nprivacy loss and model performance. Empirical studies suggest that given a\nsufficiently large number of participating clients, our proposed procedure can\nmaintain client-level differential privacy at only a minor cost in model\nperformance.\n",
"title": "Differentially Private Federated Learning: A Client Level Perspective"
} | null | null | null | null | true | null | 18218 | null | Default | null | null |
null | {
"abstract": " Okapi is a new causally consistent geo-replicated key- value store. Okapi\nleverages two key design choices to achieve high performance. First, it relies\non hybrid logical/physical clocks to achieve low latency even in the presence\nof clock skew. Second, Okapi achieves higher resource efficiency and better\navailability, at the expense of a slight increase in update visibility latency.\nTo this end, Okapi implements a new stabilization protocol that uses a\ncombination of vector and scalar clocks and makes a remote update visible when\nits delivery has been acknowledged by every data center. We evaluate Okapi with\ndifferent workloads on Amazon AWS, using three geographically distributed\nregions and 96 nodes. We compare Okapi with two recent approaches to causal\nconsistency, Cure and GentleRain. We show that Okapi delivers up to two orders\nof magnitude better performance than GentleRain and that Okapi achieves up to\n3.5x lower latency and a 60% reduction of the meta-data overhead with respect\nto Cure.\n",
"title": "Okapi: Causally Consistent Geo-Replication Made Faster, Cheaper and More Available"
} | null | null | null | null | true | null | 18219 | null | Default | null | null |
null | {
"abstract": " Epithelial cell monolayers exhibit traveling mechanical waves. We rationalize\nthis observation thanks to a hydrodynamic description of the monolayer as a\ncompressible, active and polar material. We show that propagating waves of the\ncell density, polarity, velocity and stress fields may be due to a Hopf\nbifurcation occurring above threshold values of active coupling coefficients.\n",
"title": "Emergence of epithelial cell density waves"
} | null | null | null | null | true | null | 18220 | null | Default | null | null |
null | {
"abstract": " In the context of the complex-analytic structure within the unit disk\ncentered at the origin of the complex plane, that was presented in a previous\npaper, we show that a certain class of non-integrable real functions can be\nrepresented within that same structure. In previous papers it was shown that\nessentially all integrable real functions, as well as all singular Schwartz\ndistributions, can be represented within that same complex-analytic structure.\nThe large class of non-integrable real functions which we analyze here can\ntherefore be represented side by side with those other real objects, thus\nallowing all these objects to be treated in a unified way.\n",
"title": "Complex Analysis of Real Functions IV: Non-Integrable Real Functions"
} | null | null | [
"Mathematics"
]
| null | true | null | 18221 | null | Validated | null | null |
null | {
"abstract": " Initialization of parameters in deep neural networks has been shown to have a\nbig impact on the performance of the networks (Mishkin & Matas, 2015). The\ninitialization scheme devised by He et al, allowed convolution activations to\ncarry a constrained mean which allowed deep networks to be trained effectively\n(He et al., 2015a). Orthogonal initializations and more generally orthogonal\nmatrices in standard recurrent networks have been proved to eradicate the\nvanishing and exploding gradient problem (Pascanu et al., 2012). Majority of\ncurrent initialization schemes do not take fully into account the intrinsic\nstructure of the convolution operator. Using the duality of the Fourier\ntransform and the convolution operator, Convolution Aware Initialization builds\northogonal filters in the Fourier space, and using the inverse Fourier\ntransform represents them in the standard space. With Convolution Aware\nInitialization we noticed not only higher accuracy and lower loss, but faster\nconvergence. We achieve new state of the art on the CIFAR10 dataset, and\nachieve close to state of the art on various other tasks.\n",
"title": "Convolution Aware Initialization"
} | null | null | null | null | true | null | 18222 | null | Default | null | null |
null | {
"abstract": " We consider a multitask estimation problem where nodes in a network are\ndivided into several connected clusters, with each cluster performing a\nleast-mean-squares estimation of a different random parameter vector. Inspired\nby the adapt-then-combine diffusion strategy, we propose a multitask diffusion\nstrategy whose mean stability can be ensured whenever individual nodes are\nstable in the mean, regardless of the inter-cluster cooperation weights. In\naddition, the proposed strategy is able to achieve an asymptotically unbiased\nestimation, when the parameters have same mean. We also develop an\ninter-cluster cooperation weights selection scheme that allows each node in the\nnetwork to locally optimize its inter-cluster cooperation weights. Numerical\nresults demonstrate that our approach leads to a lower average steady-state\nnetwork mean-square deviation, compared with using weights selected by various\nother commonly adopted methods in the literature.\n",
"title": "A Multitask Diffusion Strategy with Optimized Inter-Cluster Cooperation"
} | null | null | null | null | true | null | 18223 | null | Default | null | null |
null | {
"abstract": " We report 3 mm continuum, CH3CN(5-4) and 13CS(2-1) line observations with\nCARMA, in conjunction with 6 and 1.3 cm continuum VLA data, and 12 and 25\nmicron broadband data from the Subaru Telescope toward the massive proto-star\nIRAS18566+0408. The VLA data resolve the ionized jet into 4 components aligned\nin the E-W direction. Radio components A, C, and D have flat cm SEDs indicative\nof optically thin emission from ionized gas, and component B has a spectral\nindex alpha = 1.0, and a decreasing size with frequency proportional to\nfrequency to the -0.5 power. Emission from the CARMA 3 mm continuum, and from\nthe 13CS(2-1), and CH3CN(5-4) spectral lines is compact (i.e. < 6700 AU), and\npeaks near the position of VLA cm source, component B. Analysis of these lines\nindicates hot, and dense molecular gas, typical for HMCs. Our Subaru telescope\nobservations detect a single compact source, coincident with radio component B,\ndemonstrating that most of the energy in IRAS18566+0408 originates from a\nregion of size < 2400 AU. We also present UKIRT near-infrared archival data for\nIRAS18566+0408 which show extended K-band emission along the jet direction. We\ndetect an E-W velocity shift of about 10 km/sec over the HMC in the CH3CN lines\npossibly tracing the interface of the ionized jet with the surrounding core\ngas. Our data demonstrate the presence of an ionized jet at the base of the\nmolecular outflow, and support the hypothesis that massive protostars with\nO-type luminosity form with a mechanism similar to lower mass stars.\n",
"title": "High Resolution Observations of the Massive Protostar in IRAS18566+0408"
} | null | null | null | null | true | null | 18224 | null | Default | null | null |
null | {
"abstract": " High-frequency measurements and images acquired from various sources in the\nreal world often possess a degree of self-similarity and inherent regular\nscaling. When data look like a noise, the scaling exponent may be the only\ninformative feature that summarizes such data. Methods for the assessment of\nself-similarity by estimating Hurst exponent often involve analysis of rate of\ndecay in a spectrum defined in various multiresolution domains. When this\nspectrum is calculated using discrete non-decimated wavelet transforms, due to\nincreased autocorrelation in wavelet coefficients, the estimators of $H$ show\nincreased bias compared to the estimators that use traditional orthogonal\ntransforms. At the same time, non-decimated transforms have a number of\nadvantages when employed for calculation of wavelet spectra and estimation of\nHurst exponents: the variance of the estimator is smaller, input signals and\nimages could be of arbitrary size, and due to the shift-invariance, the local\nscaling can be assessed as well. We propose two methods based on robust\nestimation and resampling that alleviate the effect of increased\nautocorrelation while maintaining all advantages of non-decimated wavelet\ntransforms. The proposed methods extend the approaches in existing literature\nwhere the logarithmic transformation and pairing of wavelet coefficients are\nused for lowering the bias. In a simulation study we use fractional Brownian\nmotions with a range of theoretical Hurst exponents. For such signals for which\n\"true\" $H$ is known, we demonstrate bias reduction and overall reduction of the\nmean-squared error by the two proposed estimators. For fractional Brownian\nmotions, both proposed methods yield estimators of $H$ that are asymptotically\nnormal and unbiased.\n",
"title": "MEDL and MEDLA: Methods for Assessment of Scaling by Medians of Log-Squared Nondecimated Wavelet Coefficients"
} | null | null | null | null | true | null | 18225 | null | Default | null | null |
null | {
"abstract": " In the k-partition problem (k-PP), one is given an edge-weighted undirected\ngraph, and one must partition the node set into at most k subsets, in order to\nminimise (or maximise) the total weight of the edges that have their end-nodes\nin the same cluster. Various hierarchical variants of this problem have been\nstudied in the context of data mining. We consider a 'two-level' variant that\narises in mobile wireless communications. We show that an exact algorithm based\non intelligent preprocessing, cutting planes and symmetry-breaking is capable\nof solving small- and medium-size instances to proven optimality, and providing\nstrong lower bounds for larger instances.\n",
"title": "A Two-Level Graph Partitioning Problem Arising in Mobile Wireless Communications"
} | null | null | [
"Computer Science",
"Mathematics"
]
| null | true | null | 18226 | null | Validated | null | null |
null | {
"abstract": " The present study reports interesting findings in regard to emotional arousal\nbased activities while listening to two Hindustani classical ragas of contrast\nemotion. EEG data was taken on 5 naive listeners while they listened to two\nragas Bahar and Mia ki Malhar which are conventionally known to portray\ncontrast emotions. The EEG data were analyzed with the help of two robust non\nlinear tools viz. Adaptive Fractal Analysis (AFA) and Detrended Fluctuation\nAnalysis (DFA). A comparative study of the Hurst Exponents obtained from the\ntwo methods have been shown which shows that DFA provides more rigorous results\ncompared to AFA when it comes to the scaling analysis of biosignal data. The\nresults and implications have been discussed in detail.\n",
"title": "Emotion Specification from Musical Stimuli: An EEG Study with AFA and DFA"
} | null | null | null | null | true | null | 18227 | null | Default | null | null |
null | {
"abstract": " We show that the definition of the city boundaries can have a dramatic\ninfluence on the scaling behavior of the night-time light (NTL) as a function\nof population (POP) in the US. Precisely, our results show that the arbitrary\ngeopolitical definition based on the Metropolitan/Consolidated Metropolitan\nStatistical Areas (MSA/CMSA) leads to a sublinear power-law growth of NTL with\nPOP. On the other hand, when cities are defined according to a more natural\nagglomeration criteria, namely, the City Clustering Algorithm (CCA), an\nisometric relation emerges between NTL and population. This discrepancy is\ncompatible with results from previous works showing that the scaling behaviors\nof various urban indicators with population can be substantially different for\ndistinct definitions of city boundaries. Moreover, considering the CCA\ndefinition as more adequate than the MSA/CMSA one because the former does not\nviolate the expected extensivity between land population and area of their\ngenerated clusters, we conclude that, without loss of generality, the CCA\nmeasures of light pollution and population could be interchangeably utilized in\nfuture studies.\n",
"title": "The light pollution as a surrogate for urban population of the US cities"
} | null | null | null | null | true | null | 18228 | null | Default | null | null |
null | {
"abstract": " The radio intensity and polarization footprint of a cosmic-ray induced\nextensive air shower is determined by the time-dependent structure of the\ncurrent distribution residing in the plasma cloud at the shower front. In turn,\nthe time dependence of the integrated charge-current distribution in the plasma\ncloud, the longitudinal shower structure, is determined by interesting physics\nwhich one would like to extract such as the location and multiplicity of the\nprimary cosmic-ray collision or the values of electric fields in the atmosphere\nduring thunderstorms. To extract the structure of a shower from its footprint\nrequires solving a complicated inverse problem. For this purpose we have\ndeveloped a code that semi-analytically calculates the radio footprint of an\nextensive air shower given an arbitrary longitudinal structure. This code can\nbe used in a optimization procedure to extract the optimal longitudinal shower\nstructure given a radio footprint. On the basis of air-shower universality we\npropose a simple parametrization of the structure of the plasma cloud. This\nparametrization is based on the results of Monte-Carlo shower simulations.\nDeriving the parametrization also teaches which aspects of the plasma cloud are\nimportant for understanding the features seen in the radio-emission footprint.\nThe calculated radio footprints are compared with microscopic CoREAS\nsimulations.\n",
"title": "Analytic calculation of radio emission from parameterized extensive air showers, a tool to extract shower parameters"
} | null | null | [
"Physics"
]
| null | true | null | 18229 | null | Validated | null | null |
null | {
"abstract": " We investigate the formation of optical localized nonlinear structures,\nevolving upon a non-zero background plane wave, in a dispersive quadratic\nmedium. We show the existence of quadratic Akhmediev breathers and Peregrine\nsolitary waves, in the regime of cascading second-harmonic generation. This\nfinding opens a novel path for the excitation of extreme rogue waves and for\nthe description of modulation instability in quadratic nonlinear optics.\n",
"title": "Akhmediev Breathers and Peregrine Solitary Waves in a Quadratic Medium"
} | null | null | null | null | true | null | 18230 | null | Default | null | null |
null | {
"abstract": " The most intriguing properties of emergent materials are typically\nconsequences of highly correlated quantum states of their electronic degrees of\nfreedom. Describing those materials from first principles remains a challenge\nfor modern condensed matter theory. Here, we review, apply and discuss novel\napproaches to spectral properties of correlated electron materials, assessing\ncurrent day predictive capabilities of electronic structure calculations. In\nparticular, we focus on the recent Screened Exchange Dynamical Mean-Field\nTheory scheme and its relation to generalized Kohn-Sham theory. These concepts\nare illustrated on the transition metal pnictide BaCo$_2$As$_2$ and elemental\nzinc and cadmium.\n",
"title": "Novel approaches to spectral properties of correlated electron materials: From generalized Kohn-Sham theory to screened exchange dynamical mean field theory"
} | null | null | null | null | true | null | 18231 | null | Default | null | null |
null | {
"abstract": " The nature of three-dimensional reconnection when a twisted flux tube erupts\nduring an eruptive flare or coronal mass ejection is considered. The\nreconnection has two phases: first of all, 3D \"zipper reconnection\" propagates\nalong the initial coronal arcade, parallel to the polarity inversion line\n(PIL), then subsequent quasi-2D \"main phase reconnection\" in the low corona\naround a flux rope during its eruption produces coronal loops and chromospheric\nribbons that propagate away from the PIL in a direction normal to it.\nOne scenario starts with a sheared arcade: the zipper reconnection creates a\ntwisted flux rope of roughly one turn ($2\\pi$ radians of twist), and then main\nphase reconnection builds up the bulk of the erupting flux rope with a\nrelatively uniform twist of a few turns. A second scenario starts with a\npre-existing flux rope under the arcade. Here the zipper phase can create a\ncore with many turns that depend on the ratio of the magnetic fluxes in the\nnewly formed flare ribbons and the new flux rope. Main phase reconnection then\nadds a layer of roughly uniform twist to the twisted central core. Both phases\nand scenarios are modeled in a simple way that assumes the initial magnetic\nflux is fragmented along the PIL. The model uses conservation of magnetic\nhelicity and flux, together with equipartition of magnetic helicity, to deduce\nthe twist of the erupting flux rope in terms the geometry of the initial\nconfiguration.\nInterplanetary observations show some flux ropes have a fairly uniform twist,\nwhich could be produced when the zipper phase and any pre-existing flux rope\npossess small or moderate twist (up to one or two turns). Other interplanetary\nflux ropes have highly twisted cores (up to five turns), which could be\nproduced when there is a pre-existing flux rope and an active zipper phase that\ncreates substantial extra twist.\n",
"title": "Flux-Rope Twist in Eruptive Flares and CMEs: due to Zipper and Main-Phase Reconnection"
} | null | null | null | null | true | null | 18232 | null | Default | null | null |
null | {
"abstract": " We observe that any finite-dimensional central simple 5-graded Lie algebra\nover over a field k of characteristic not 2,3 is necessarily classical, i.e. a\ntwisted form of a Chevalley Lie algebra. Consequently, the classification of\ncentral simple structurable algebras and Kantor pairs over fields of\ncharacteristic 5 derives from the classification of simple algebraic groups.\nUsing the classification of nilpotent conjugacy classes, we list all 5-gradings\non Lie algebras of simple algebraic groups that give rise to simple\nstructurable algebras over algebraically closed fields.\n",
"title": "On the classification of Kantor pairs and structurable algebras in characteristic 5"
} | null | null | [
"Mathematics"
]
| null | true | null | 18233 | null | Validated | null | null |
null | {
"abstract": " Cross-lingual text classification(CLTC) is the task of classifying documents\nwritten in different languages into the same taxonomy of categories. This paper\npresents a novel approach to CLTC that builds on model distillation, which\nadapts and extends a framework originally proposed for model compression. Using\nsoft probabilistic predictions for the documents in a label-rich language as\nthe (induced) supervisory labels in a parallel corpus of documents, we train\nclassifiers successfully for new languages in which labeled training data are\nnot available. An adversarial feature adaptation technique is also applied\nduring the model training to reduce distribution mismatch. We conducted\nexperiments on two benchmark CLTC datasets, treating English as the source\nlanguage and German, French, Japan and Chinese as the unlabeled target\nlanguages. The proposed approach had the advantageous or comparable performance\nof the other state-of-art methods.\n",
"title": "Cross-lingual Distillation for Text Classification"
} | null | null | null | null | true | null | 18234 | null | Default | null | null |
null | {
"abstract": " We map an interacting helical liquid system, coupled to an external magnetic\nfield and s-wave superconductor, to an XYZ spin system, and it undergoes\nMajorana-Ising transition by tuning of parameters. In the Majorana state,\nlowest excitation gap decays exponentially with system size, and the system has\ndegenerate ground state in the thermodynamic limit. On the contrary, the gap\nopens in the Ising phase even in the thermodynamic limit. We also study other\ncriteria to characterize the transition, such as edge spin correlation with its\nneighbor $C(r=1)$, local susceptibility $\\chi_i$, superconducting order\nparameter of edge spin $P(r=1)$, and longitudinal structure factor $S(k)$. The\nground state degeneracy and three other criteria lead to the same critical\nvalue of parameters for Majorana-Ising phase transition in the thermodynamic\nlimit. We study, for the first time, the entanglement spectrum of the reduced\ndensity matrix of the helical liquid system. The system shows finite Schmidt\ngap and non-degeneracy of the entanglement spectrum in the Ising limit. The\nSchmidt gap closes in the Majorana state, and all the eigenvalues are either\ndoubly or multiply degenerate.\n",
"title": "Characterization of Majorana-Ising phase transition in a helical liquid system"
} | null | null | null | null | true | null | 18235 | null | Default | null | null |
null | {
"abstract": " We consider nonnegative solutions to $-\\Delta u=f(u)$ in half-planes and\nstrips, under zero Dirichlet boundary condition. Exploiting a\nrotating$\\&$sliding line technique, we prove symmetry and monotonicity\nproperties of the solutions, under very general assumptions on the nonlinearity\n$f$. In fact we provide a unified approach that works in all the cases\n$f(0)<0$, $f(0)= 0$ or $f(0)> 0$. Furthermore we make the effort to deal with\nnonlinearities $f$ that may be not locally-Lipschitz continuous. We also\nprovide explicite examples showing the sharpness of our assumptions on the\nnonlinear function $f$.\n",
"title": "Monotonicity and symmetry of nonnegative solutions to $ -Δu=f(u) $ in half-planes and strips"
} | null | null | [
"Mathematics"
]
| null | true | null | 18236 | null | Validated | null | null |
null | {
"abstract": " Rapidly growing product lines and services require a finer-granularity\nforecast that considers geographic locales. However the open question remains,\nhow to assess the quality of a spatio-temporal forecast? In this manuscript we\nintroduce a metric to evaluate spatio-temporal forecasts. This metric is based\non an Opti- mal Transport (OT) problem. The metric we propose is a constrained\nOT objec- tive function using the Gini impurity function as a regularizer. We\ndemonstrate through computer experiments both the qualitative and the\nquantitative charac- teristics of the Gini regularized OT problem. Moreover, we\nshow that the Gini regularized OT problem converges to the classical OT\nproblem, when the Gini regularized problem is considered as a function of\n{\\lambda}, the regularization parame-ter. The convergence to the classical OT\nsolution is faster than the state-of-the-art Entropic-regularized OT[Cuturi,\n2013] and results in a numerically more stable algorithm.\n",
"title": "Gini-regularized Optimal Transport with an Application to Spatio-Temporal Forecasting"
} | null | null | null | null | true | null | 18237 | null | Default | null | null |
null | {
"abstract": " The entanglement entropy (EE) of quantum systems is often used as a test of\nlow-energy descriptions by conformal field theory (CFT). Here we point out that\nthis is not a reliable indicator, as the EE often shows the same behavior even\nwhen a CFT description is not correct (as long as the system is asymptotically\nscale-invariant). We use constraints on the scaling dimension given by the CFT\nwith SU(2) symmetry to provide alternative tests with two- and four-point\ncorrelation functions, showing examples for quantum spin models in 1+1\ndimensions. In the case of a critical amplitude-product state expressed in the\nvalence-bond basis (where the amplitudes decay as a power law of the bond\nlength and the wave function is the product of all bond amplitudes), we show\nthat even though the EE exhibits the expected CFT behavior, there is no CFT\ndescription of this state. We provide numerical tests of the behavior predicted\nby CFT for the correlation functions in the critical transverse-field Ising\nchain and the $J$-$Q$ spin chain, where the conformal structure is well\nunderstood. That behavior is not reproduced in the amplitude-product state.\n",
"title": "Indicators of Conformal Field Theory: entanglement entropy and multiple-point correlators"
} | null | null | null | null | true | null | 18238 | null | Default | null | null |
null | {
"abstract": " We argue that the preferred classical variables that emerge from a pure\nquantum state are determined by its entanglement structure in the form of\nredundant records: information shared between many subsystems. Focusing on the\nearly universe, we ask how classical metric perturbations emerge from vacuum\nfluctuations in an inflationary background. We show that the squeezing of the\nquantum state for super-horizon modes, along with minimal gravitational\ninteractions, leads to decoherence and to an exponential number of records of\nmetric fluctuations on very large scales, $\\lambda/\\lambda_{\\rm\nHubble}>\\Delta_\\zeta^{-2/3}$, where $\\Delta_\\zeta\\lesssim 10^{-5}$ is the\namplitude of scalar metric fluctuations. This determines a preferred\ndecomposition of the inflationary wavefunction into orthogonal \"branches\"\ncorresponding to classical metric perturbations, which defines an inflationary\nentropy production rate and accounts for the emergence of stochastic,\ninhomogeneous spacetime geometry.\n",
"title": "Classical Entanglement Structure in the Wavefunction of Inflationary Fluctuations"
} | null | null | null | null | true | null | 18239 | null | Default | null | null |
null | {
"abstract": " The momentum conservation law is applied to analyse the dynamics of pulsejet\nengine in vertical motion in a uniform gravitational field in the absence of\nfriction. The model predicts existence of a terminal speed given frequency of\nthe short pulses. The conditions that the engine does not return to the\nstarting position are identified. The number of short periodic pulses after\nwhich the engine returns to the starting position is found to be independent of\nthe exhaust velocity and gravitational field intensity for certain frequency of\nthe pulses. The pulsejet engine and turbojet engine aircraft models of dynamics\nare compared. Also the octopus dynamics is modelled. The paper is addressed to\nintermediate undergraduate students of classical mechanics and aerospace\nengineering.\n",
"title": "Pulsejet engine dynamics in vertical motion using momentum conservation"
} | null | null | null | null | true | null | 18240 | null | Default | null | null |
null | {
"abstract": " Whereas maintenance has been recognized as an important and effective means\nfor risk management in power systems, it turns out to be intractable if\ncascading blackout risk is considered due to the extremely high computational\ncomplexity. In this paper, based on the inference from the blackout simulation\ndata, we propose a methodology to efficiently identify the most influential\ncomponent(s) for mitigating cascading blackout risk in a large power system. To\nthis end, we first establish an analytic relationship between maintenance\nstrategies and blackout risk estimation by inferring from the data of cascading\noutage simulations. Then we formulate the component maintenance decision-making\nproblem as a nonlinear 0-1 programming. Afterwards, we quantify the credibility\nof blackout risk estimation, leading to an adaptive method to determine the\nleast required number of simulations, which servers as a crucial parameter of\nthe optimization model. Finally, we devise two heuristic algorithms to find\napproximate optimal solutions to the model with very high efficiency. Numerical\nexperiments well manifest the efficacy and high efficiency of our methodology.\n",
"title": "Mitigating Blackout Risk via Maintenance : Inference from Simulation Data"
} | null | null | null | null | true | null | 18241 | null | Default | null | null |
null | {
"abstract": " In the 1950's Hopf gave examples of non-round convex 2-spheres in Euclidean\n3-space with rotational symmetry that satisfy a linear relationship between\ntheir principal curvatures. In this paper we investigate conditions under which\nevolving a smooth rotationally symmetric sphere by a linear combination of its\nradii of curvature yields a Hopf sphere. When the coefficients of the flow have\ncertain integer values, the fate of an initial sphere is entirely determined by\nthe local geometry of its isolated umbilic points. A surprising variety of\nbehaviours is uncovered: convergence to round spheres and non-round Hopf\nspheres, as well as divergence to infinity.\nThe critical quantity is the rate of vanishing of the astigmatism - the\ndifference of the radii of curvature - at the isolated umbilic points. It is\nproven that the size of this quantity versus the coefficient in the flow\nfunction determines the fate of the evolution.\nThe geometric setting for the equation is Radius of Curvature space, viewed\nas a pair of hyperbolic/AdS half-planes joined along their boundary, the\numbilic horizon. A rotationally symmetric sphere determines a parameterized\ncurve in this plane with end-points on the umbilic horizon. The slope of the\ncurve at the umbilic horizon is linked by the Codazzi-Mainardi equations to the\nrate of vanishing of astigmatism, and for generic initial conditions can be\nused to determine the outcome of the flow.\nThe slope can jump during the flow, and a number of examples are given:\ninstant jumps of the initial slope, as well as umbilic circles that contract to\npoints in finite time and 'pop' the slope. Finally, we present soliton-like\nsolutions: curves that evolve under linear flows by mutual hyperbolic/AdS\nisometries (dilation and translation) of Radius of Curvature space. A\nforthcoming paper will apply these geometric ideas to non-linear curvature\nflows.\n",
"title": "Evolving to Non-round Weingarten Spheres: Integer Linear Hopf Flows"
} | null | null | [
"Mathematics"
]
| null | true | null | 18242 | null | Validated | null | null |
null | {
"abstract": " We revisit the linear programming approach to deterministic, continuous time,\ninfinite horizon discounted optimal control problems. In the first part, we\nrelax the original problem to an infinite-dimensional linear program over a\nmeasure space and prove equivalence of the two formulations under mild\nassumptions, significantly weaker than those found in the literature until now.\nThe proof is based on duality theory and mollification techniques for\nconstructing approximate smooth subsolutions to the associated\nHamilton-Jacobi-Bellman equation. In the second part, we assume polynomial data\nand use Lasserre's hierarchy of primal-dual moment-sum-of-squares semidefinite\nrelaxations to approximate the value function and design an approximate optimal\nfeedback controller. We conclude with an illustrative example.\n",
"title": "On Infinite Linear Programming and the Moment Approach to Deterministic Infinite Horizon Discounted Optimal Control Problems"
} | null | null | null | null | true | null | 18243 | null | Default | null | null |
null | {
"abstract": " Light-matter interaction processes are significantly affected by surrounding\nelectromagnetic environment. Dielectric materials are usually introduced into\nan interaction picture via their classical properties, e.g. permittivity,\nappearing in constitutive relations. While this approach was proven to be\napplicable in many occasions, it might face limitations when an emitter is\nsituated very close to a material boundary. In this case nonlocal extend of a\nquantum wave function of an emitter becomes comparable with a distance to a\nboundary and a lattice constant of a material. Here a semi-classical model,\ntaking into account material's granularity, is developed. In particular,\nspontaneous emission process in the vicinity of flat boundaries is considered.\nThe material boundary is divided into a pair areas - far zone is modeled as a\ncontinuous phase, while the near zone next to a nonlocal emitter is represented\nwith a discrete array of polarizable particles. This array resembles optical\nproperties of the continuous phase under the standard homogenization procedure.\nLocal field effects were shown to lead orders of magnitude corrections to\nspontaneous emission rates in the case of sub-nanometer emitter-surface\nseparation distances. The developed mesoscopic model enables addressing few\naspects of local field corrections in quite complex scenarios, where quantum ab\ninitio techniques yet face challenges owing to involved computational\ncomplexity. The developed method could be utilized for designs of quantum\nsources and networks, enhanced with structured electromagnetic environment.\n",
"title": "Granular permittivity representation in extremely near-field light-matter interactions processes"
} | null | null | null | null | true | null | 18244 | null | Default | null | null |
null | {
"abstract": " Bechgaard salts, (TMTSF)2X (TMTSF = tetramethyl tetraselenafulvalene and X =\ncomplex anion), form the most popular series of organic superconductors. In\nthese salts, TMTSF molecules act as super-electron donor and X as acceptor. We\ncomputationally examine the electronic structure and properties of X in\ncommonly used (TMTSF)2X (X = NO3, BF4, ClO4, PF6) superconductors and notice\nthat they belong to the class of superhalogens due to their higher vertical\ndetachment energy than halogen anions. This prompted us to choose other\nsuperhalogens such as X = BO2, BH4, B2F7, AuF6 and study their (TMTSF)2X\ncomplexes. Our findings suggest that these complexes behave more or less\nsimilar to those of established (TMTSF)2X superconductors, particularly for X =\nBO2 and B2F7. We, therefore, believe that the concept of superhalogen can be\nsuccessfully applied in the design of novel organic superconductors.\n",
"title": "Application of Superhalogens in the Design of Organic Superconductors"
} | null | null | null | null | true | null | 18245 | null | Default | null | null |
null | {
"abstract": " We introduce an inhomogeneous bosonic mixture composed of two kinds of\nhard-core and semi-hard-core bosons with different nilpotency conditions and\ndemonstrate that in contrast with the standard hard-core Bose-Hubbard model,\nour bosonic mixture with nearest- and next-nearest-neighbor interactions on a\nsquare lattice develops the checkerboard supersolid phase characterized by the\nsimultaneous superfluid and checkerboard solid orders. Our bosonic mixture is\ncreated from a two-orbital Bose-Hubbard model including two kinds of bosons: a\nsingle-orbital boson and a two-orbital boson. By mapping the bosonic mixture to\nan anisotropic inhomogeneous spin model in the presence of a magnetic field, we\nstudy the ground-state phase diagram of the model by means of cluster mean\nfield theory and linear spin-wave theory and show that various phases such as\nsolid, superfluid, supersolid, and Mott insulator appear in the phase diagram\nof the mixture. Competition between the interactions and magnetic field causes\nthe mixture to undergo different kinds of first- and second-order phase\ntransitions. By studying the behavior of the spin-wave excitations, we find the\nreasons of all first- and second-order phase transitions. We also obtain the\ntemperature phase diagram of the system using cluster mean field theory. We\nshow that the checkerboard supersolid phase persists at finite temperature\ncomparable with the interaction energies of bosons.\n",
"title": "Inhomogeneous hard-core bosonic mixture with checkerboard supersolid phase: Quantum and thermal phase diagram"
} | null | null | null | null | true | null | 18246 | null | Default | null | null |
null | {
"abstract": " We introduce new natural generalizations of the classical descent and\ninversion statistics for permutations, called width-$k$ descents and width-$k$\ninversions. These variations induce generalizations of the excedance and major\nstatistics, providing a framework in which the most well-known\nequidistributivity results for classical statistics are paralleled. We explore\nadditional relationships among the statistics providing specific formulas in\ncertain special cases. Moreover, we explore the behavior of these width-$k$\nstatistics in the context of pattern avoidance.\n",
"title": "Width-$k$ Generalizations of Classical Permutation Statistics"
} | null | null | null | null | true | null | 18247 | null | Default | null | null |
null | {
"abstract": " This paper presents Klout Topics, a lightweight ontology to describe social\nmedia users' topics of interest and expertise. Klout Topics is designed to: be\nhuman-readable and consumer-friendly; cover multiple domains of knowledge in\ndepth; and promote data extensibility via knowledge base entities. We discuss\nwhy this ontology is well-suited for text labeling and interest modeling\napplications, and how it compares to available alternatives. We show its\ncoverage against common social media interest sets, and examples of how it is\nused to model the interests of over 780M social media users on Klout.com.\nFinally, we open the ontology for external use.\n",
"title": "Klout Topics for Modeling Interests and Expertise of Users Across Social Networks"
} | null | null | null | null | true | null | 18248 | null | Default | null | null |
null | {
"abstract": " Studying the effects of groups of Single Nucleotide Polymorphisms (SNPs), as\nin a gene, genetic pathway, or network, can provide novel insight into complex\ndiseases, above that which can be gleaned from studying SNPs individually.\nCommon challenges in set-based genetic association testing include weak effect\nsizes, correlation between SNPs in a SNP-set, and scarcity of signals, with\nsingle-SNP effects often ranging from extremely sparse to moderately sparse in\nnumber. Motivated by these challenges, we propose the Generalized Berk-Jones\n(GBJ) test for the association between a SNP-set and outcome. The GBJ extends\nthe Berk-Jones (BJ) statistic by accounting for correlation among SNPs, and it\nprovides advantages over the Generalized Higher Criticism (GHC) test when\nsignals in a SNP-set are moderately sparse. We also provide an analytic p-value\ncalculation procedure for SNP-sets of any finite size. Using this p-value\ncalculation, we illustrate that the rejection region for GBJ can be described\nas a compromise of those for BJ and GHC. We develop an omnibus statistic as\nwell, and we show that this omnibus test is robust to the degree of signal\nsparsity. An additional advantage of our method is the ability to conduct\ninference using individual SNP summary statistics from a genome-wide\nassociation study. We evaluate the finite sample performance of the GBJ though\nsimulation studies and application to gene-level association analysis of breast\ncancer risk.\n",
"title": "Set-Based Tests for Genetic Association Using the Generalized Berk-Jones Statistic"
} | null | null | null | null | true | null | 18249 | null | Default | null | null |
null | {
"abstract": " The theme of this paper is three-phase distribution system modeling suitable\nfor the Z-Bus load-flow. Detailed models of wye and delta constant-power,\nconstant-current, and constant-impedance loads are presented. Models of\ntransmission lines, voltage regulators, and transformers that build the bus\nadmittance matrix (Y-Bus) are laid out. The Z-Bus load-flow is then reviewed\nand the singularity of the Y-Bus in case of certain transformer connections is\nrigorously discussed. Based on realistic assumptions and conventional\nmodifications, the invertibility of the Y-Bus is proved. Last but not least,\nthe MATLAB scripts that construct the detailed component models for the IEEE\n37-bus, IEEE 123-bus, and 8500-node feeders as well as the European 906-bus\nlow-voltage feeder are provided.\n",
"title": "Comprehensive Modeling of Three-Phase Distribution Systems via the Bus Admittance Matrix"
} | null | null | null | null | true | null | 18250 | null | Default | null | null |
null | {
"abstract": " We develop a general framework for $c$-vectors of 2-Calabi--Yau categories,\nwhich deals with cluster tilting subcategories that are not reachable from each\nother and contain infinitely many indecomposable objects. It does not rely on\niterative sequences of mutations.\nWe prove a categorical (infinite-rank) generalization of the\nNakanishi--Zelevinsky duality for $c$-vectors and establish two formulae for\nthe effective computation of $c$-vectors -- one in terms of indices and the\nother in terms of dimension vectors for cluster tilted algebras.\nIn this framework, we construct a correspondence between the $c$-vectors of\nthe cluster categories ${\\mathscr{C}}(A_{\\infty})$ of type $A_{\\infty}$ due to\nIgusa--Todorov and the roots of the Borel subalgebras of\n${\\mathfrak{sl}}_{\\infty}$. Contrary to the finite dimensional case, the Borel\nsubalgebras of ${\\mathfrak{sl}}_{\\infty}$ are not conjugate to each other. On\nthe categorical side, the cluster tilting subcategories of\n${\\mathscr{C}}(A_{\\infty})$ exhibit different homological properties. The\ncorrespondence builds a bridge between the two classes of objects.\n",
"title": "$c$-vectors of 2-Calabi--Yau categories and Borel subalgebras of ${\\mathfrak{sl}}_{\\infty}$"
} | null | null | null | null | true | null | 18251 | null | Default | null | null |
null | {
"abstract": " In this thesis we study the lateral electrostatic interaction between a pair\nof non-identical, moderately charged colloidal particles trapped at an\nelectrolyte interface in the limit of short inter-particle separations. Using a\nsimplified model system we solve the problem analytically within the framework\nof linearised Poisson-Boltzmann theory and classical density functional theory.\nIn the first step, we calculate the electrostatic potential inside the system\nexactly as well as within the widely used superposition approximation. Then\nthese results are used to calculate the surface and line interaction energy\ndensities between the particles. Contrary to the case of identical particles,\ndepending upon the parameters of the system, we obtain that both the surface\nand the line interaction can vary non-monotonically with varying separation\nbetween the particles and the superposition approximation fails to predict the\ncorrect qualitative behaviours in most cases. Additionally, the superposition\napproximation is unable to predict the energy contributions quantitatively even\nat large distances. We also provide expression for the constant (independent of\nthe inter-particle separation) interaction parameters, i.e., the surface\ntension, the line tension and the interfacial tension. Our results are expected\nto be of use for modelling particle-interaction at fluid interfaces and, in\nparticular, for emulsion stabilization using oppositely charged particles.\n",
"title": "Electrostatic interaction between non-identical charged particles at an electrolyte interface"
} | null | null | null | null | true | null | 18252 | null | Default | null | null |
null | {
"abstract": " In this paper we study sectional curvature bounds for Riemannian manifolds\nwith density from the perspective of a weighted torsion free connection\nintroduced recently by the last two authors. We develop two new tools for\nstudying weighted sectional curvature bounds: a new weighted Rauch comparison\ntheorem and a modified notion of convexity for distance functions. As\napplications we prove generalizations of theorems of Preissman and Byers for\nnegative curvature, the (homeomorphic) quarter-pinched sphere theorem, and\nCheeger's finiteness theorem. We also improve results of the first two authors\nfor spaces of positive weighted sectional curvature and symmetry.\n",
"title": "The weighted connection and sectional curvature for manifolds with density"
} | null | null | null | null | true | null | 18253 | null | Default | null | null |
null | {
"abstract": " This paper proposes a novel method to automatically enforce controls and\nlimits for Voltage Source Converter (VSC) based multi-terminal HVDC in the\nNewton power flow iteration process. A general VSC MT-HVDC model with primary\nPQ or PV control and secondary voltage control is formulated. Both the\ndependent and independent variables are included in the propose formulation so\nthat the algebraic variables of the VSC MT-HVDC are adjusted simultaneously.\nThe proposed method also maintains the number of equations and the dimension of\nthe Jacobian matrix unchanged so that, when a limit is reached and a control is\nreleased, the Jacobian needs no re-factorization. Simulations on the IEEE\n14-bus and Polish 9241-bus systems are performed to demonstrate the\neffectiveness of the method.\n",
"title": "Control and Limit Enforcements for VSC Multi-Terminal HVDC in Newton Power Flow"
} | null | null | [
"Computer Science"
]
| null | true | null | 18254 | null | Validated | null | null |
null | {
"abstract": " The paper is devoted to the contribution in the Probability Theory of the\nwell-known Soviet mathematician Alexander Yakovlevich Khintchine (1894-1959).\nSeveral of his results are described, in particular those fundamental results\non the infinitely divisible distributions. Attention is paid also to his\ninteraction with Paul Levy. The content of the paper is related to our joint\nbook The Legacy of A.Ya. Khintchine's Work in Probability Theory, published in\n2010 by Cambridge Scientific Publishers.\n",
"title": "A.Ya. Khintchine's Work in Probability Theory"
} | null | null | null | null | true | null | 18255 | null | Default | null | null |
null | {
"abstract": " This paper studies dynamic complexity under definable change operations in\nthe DynFO framework by Patnaik and Immerman. It is shown that for changes\ndefinable by parameter-free first-order formulas, all (uniform) $AC^1$ queries\ncan be maintained by first-order dynamic programs. Furthermore, many\nmaintenance results for single-tuple changes are extended to more powerful\nchange operations: (1) The reachability query for undirected graphs is\nfirst-order maintainable under single tuple changes and first-order defined\ninsertions, likewise the reachability query for directed acyclic graphs under\nquantifier-free insertions. (2) Context-free languages are first-order\nmaintainable under $\\Sigma_1$-defined changes. These results are complemented\nby several inexpressibility results, for example, that the reachability query\ncannot be maintained by quantifier-free programs under definable,\nquantifier-free deletions.\n",
"title": "Dynamic Complexity under Definable Changes"
} | null | null | null | null | true | null | 18256 | null | Default | null | null |
null | {
"abstract": " This report documents the implementation of several related 1D heat flow\nproblems in the verification package ExactPack. In particular, the planar\nsandwich class defined by Dawes et al., as well as the classes\nPlanarSandwichHot, PlanarSandwichHalf, and other generalizations of the planar\nsandwich problem, are defined and documented here. A rather general treatment\nof 1D heat flow is presented, whose main results have been implemented in the\nclass Rod1D. All planar sandwich classes are derived from the parent class\nRod1D.\n",
"title": "The Planar Sandwich and Other 1D Planar Heat Flow Test Problems in ExactPack"
} | null | null | null | null | true | null | 18257 | null | Default | null | null |
null | {
"abstract": " We show that state-of-the-art services for creating trusted timestamps in\nblockchain-based networks do not adequately allow for timestamping of web\npages. They accept data by value (e.g., images and text), but not by reference\n(e.g., URIs of web pages). Also, we discuss difficulties in repeatedly\ngenerating the same cryptographic hash value of an archived web page. We then\nintroduce several requirements to be fulfilled in order to produce repeatable\nhash values for archived web pages.\n",
"title": "Difficulties of Timestamping Archived Web Pages"
} | null | null | null | null | true | null | 18258 | null | Default | null | null |
null | {
"abstract": " This paper is a contribution to the classical cops and robber problem on a\ngraph, directed to two-dimensional grids and toroidal grids. These studies are\ngenerally aimed at determining the minimum number of cops needed to capture the\nrobber and proposing algorithms for the capture. We apply some new concepts to\npropose a new solution to the problem on grids that was already solved under a\ndifferent approach, and apply these concepts to give efficient algorithms for\nthe capture on toroidal grids. As for grids, we show that two cops suffice even\nin a semi-torus (i.e. a grid with toroidal closure in one dimension) and three\ncops are necessary and sufficient in a torus. Then we treat the problem in\nfunction of any number k of cops, giving efficient algorithms for grids and\ntori and computing lower and upper bounds on the capture time. Conversely we\ndetermine the minimum value of k needed for any given capture time and study a\npossible speed-up phenomenon.\n",
"title": "Cops and robber on grids and tori"
} | null | null | null | null | true | null | 18259 | null | Default | null | null |
null | {
"abstract": " Wikipedia is a community-created online encyclopedia; arguably, it is the\nmost popular and largest knowledge resource on the Internet. Thus, reliability\nand neutrality are of high importance for Wikipedia. Previous research [3]\nreveals gender bias in Google search results for many professions and\noccupations. Also, Wikipedia was criticized for existing gender bias in\nbiographies [4] and gender gap in the editor community [5, 6]. Thus, one could\nexpect that gender bias related to professions and occupations may be present\nin Wikipedia. The term gender bias is used here in the sense of conscious or\nunconscious favoritism towards one gender over another [47] with respect to\nprofessions and occupations. The objective of this work is to identify and\nassess gender bias. To this end, the German Wikipedia articles about\nprofessions and occupations were analyzed on three dimensions: redirections,\nimages, and people mentioned in the articles. This work provides evidence for\nsystematic overrepresentation of men in all three dimensions; female bias is\nonly present for a few professions.\n",
"title": "Measuring Gender Inequalities of German Professions on Wikipedia"
} | null | null | null | null | true | null | 18260 | null | Default | null | null |
null | {
"abstract": " People change their physical contacts as a preventive response to infectious\ndisease propagations. Yet, only a few mathematical models consider the coupled\ndynamics of the disease propagation and the contact adaptation process. This\npaper presents a model where each agent has a default contact neighborhood set,\nand switches to a different contact set once she becomes alert about infection\namong her default contacts. Since each agent can adopt either of two possible\nneighborhood sets, the overall contact network switches among 2^N possible\nconfigurations. Notably, a two-layer network representation can fully model the\nunderlying adaptive, state-dependent contact network. Contact adaptation\ninfluences the size of the disease prevalence and the epidemic threshold---a\ncharacteristic measure of a contact network robustness against epidemics---in a\nnonlinear fashion. Particularly, the epidemic threshold for the presented\nadaptive contact network belongs to the solution of a nonlinear\nPerron-Frobenius (NPF) problem, which does not depend on the contact adaptation\nrate monotonically. Furthermore, the network adaptation model predicts a\ncounter-intuitive scenario where adaptively changing contacts may adversely\nlead to lower network robustness against epidemic spreading if the contact\nadaptation is not fast enough. An original result for a class of NPF problems\nfacilitate the analytical developments in this paper.\n",
"title": "Contact Adaption during Epidemics: A Multilayer Network Formulation Approach"
} | null | null | null | null | true | null | 18261 | null | Default | null | null |
null | {
"abstract": " We study the problem of nonparametric estimation under $\\bL_p$-loss, $p\\in\n[1,\\infty)$, in the framework of the convolution structure density model on\n$\\bR^d$. This observation scheme is a generalization of two classical\nstatistical models, namely density estimation under direct and indirect\nobservations. In Part I the original pointwise selection rule from a family of\n\"kernel-type\" estimators is proposed. For the selected estimator, we prove an\n$\\bL_p$-norm oracle inequality and several of its consequences. In Part II the\nproblem of adaptive minimax estimation under $\\bL_p$--loss over the scale of\nanisotropic Nikol'skii classes is addressed. We fully characterize the behavior\nof the minimax risk for different relationships between regularity parameters\nand norm indexes in the definitions of the functional class and of the risk. We\nprove that the selection rule proposed in Part I leads to the construction of\nan optimally or nearly optimally (up to logarithmic factor) adaptive estimator.\n",
"title": "Estimation in the convolution structure density model. Part I: oracle inequalities"
} | null | null | [
"Mathematics",
"Statistics"
]
| null | true | null | 18262 | null | Validated | null | null |
null | {
"abstract": " Direct imaging suggests that there is a Jovian exoplanet around the primary\nA-star in the triple-star system HD131399. We investigate a high-quality\nspectrum of the primary component HD131399A obtained with FEROS on the ESO/MPG\n2.2m telescope, aiming to characterise the star's atmospheric and fundamental\nparameters, and to determine elemental abundances at high precision and\naccuracy. The aim is to constrain the chemical composition of the birth cloud\nof the system and therefore the bulk composition of the putative planet. A\nhybrid non-local thermal equilibrium (non-LTE) model atmosphere technique is\nadopted for the quantitative spectral analysis. Comparison with the most recent\nstellar evolution models yields the fundamental parameters. The atmospheric and\nfundamental stellar parameters of HD131399A are constrained to Teff=9200+-100\nK, log g=4.37+-0.10, M=1.95+0.08-0.06 Msun, R=1.51+0.13-0.10 Rsun, and log\nL/Lsun=1.17+-0.07, locating the star on the zero-age main sequence. Non-LTE\neffects on the derived metal abundances are often smaller than 0.1dex, but can\nreach up to ~0.8dex for individual lines. The observed lighter elements up to\ncalcium are overall consistent with present-day cosmic abundances, with a C/O\nratio of 0.45$\\pm$0.07 by number, while the heavier elements show mild\noverabundances. We conclude that the birth cloud of the system had a standard\nchemical composition, but we witness the onset of the Am phenomenon in the\nslowly rotating star. We furthermore show that non-LTE analyses have the\npotential to solve the remaining discrepancies between observed abundances and\npredictions by diffusion models for Am stars. Moreover, the present case allows\nmass loss, not turbulent mixing, to be identified as the main transport process\ncompeting with diffusion in very young Am stars.\n",
"title": "Candidate exoplanet host HD131399A: a nascent Am star"
} | null | null | null | null | true | null | 18263 | null | Default | null | null |
null | {
"abstract": " In this paper, we propose a Quantum variation of combinatorial games,\ngeneralizing the Quantum Tic-Tac-Toe proposed by Allan Goff. A combinatorial\ngame is a two-player game with no chance and no hidden information, such as Go\nor Chess. In this paper, we consider the possibility of playing superpositions\nof moves in such games. We propose different rulesets depending on when\nsuperposed moves should be played, and prove that all these rulesets may lead\nsimilar games to different outcomes. We then consider Quantum variations of the\ngame of Nim. We conclude with some discussion on the relative interest of the\ndifferent rulesets.\n",
"title": "Toward Quantum Combinatorial Games"
} | null | null | null | null | true | null | 18264 | null | Default | null | null |
null | {
"abstract": " For the Gegenbauer weight function $w_{\\lambda}(t)=(1-t^2)^{\\lambda-1/2}$,\n$\\lambda>-1/2$, we denote by $\\Vert\\cdot\\Vert_{w_{\\lambda}}$ the associated\n$L_2$-norm, $$ \\Vert\nf\\Vert_{w_{\\lambda}}:=\\Big(\\int_{-1}^{1}w_{\\lambda}(t)f^2(t)\\,dt\\Big)^{1/2}. $$\nWe study the Markov inequality $$ \\Vert p^{\\prime}\\Vert_{w_{\\lambda}}\\leq\nc_{n}(\\lambda)\\,\\Vert p\\Vert_{w_{\\lambda}},\\qquad p\\in \\mathcal{P}_n, $$ where\n$\\mathcal{P}_n$ is the class of algebraic polynomials of degree not exceeding\n$n$. Upper and lower bounds for the best Markov constant $c_{n}(\\lambda)$ are\nobtained, which are valid for all $n\\in \\mathbb{N}$ and $\\lambda>-\\frac{1}{2}$.\n",
"title": "Markov $L_2$ inequality with the Gegenbauer weight"
} | null | null | [
"Mathematics"
]
| null | true | null | 18265 | null | Validated | null | null |
null | {
"abstract": " We produce precise estimates for the Kogbetliantz kernel for the\napproximation of functions on the sphere. Furthermore, we propose and study a\nnew approximation kernel, which has slightly better properties.\n",
"title": "A Note on Some Approximation Kernels on the Sphere"
} | null | null | [
"Mathematics"
]
| null | true | null | 18266 | null | Validated | null | null |
null | {
"abstract": " We identify a strong equivalence between neural network based machine\nlearning (ML) methods and the formulation of statistical data assimilation\n(DA), known to be a problem in statistical physics. DA, as used widely in\nphysical and biological sciences, systematically transfers information in\nobservations to a model of the processes producing the observations. The\ncorrespondence is that layer label in the ML setting is the analog of time in\nthe data assimilation setting. Utilizing aspects of this equivalence we discuss\nhow to establish the global minimum of the cost functions in the ML context,\nusing a variational annealing method from DA. This provides a design method for\noptimal networks for ML applications and may serve as the basis for\nunderstanding the success of \"deep learning\". Results from an ML example are\npresented.\nWhen the layer label is taken to be continuous, the Euler-Lagrange equation\nfor the ML optimization problem is an ordinary differential equation, and we\nsee that the problem being solved is a two point boundary value problem. The\nuse of continuous layers is denoted \"deepest learning\". The Hamiltonian version\nprovides a direct rationale for back propagation as a solution method for the\ncanonical momentum; however, it suggests other solution methods are to be\npreferred.\n",
"title": "Machine Learning as Statistical Data Assimilation"
} | null | null | null | null | true | null | 18267 | null | Default | null | null |
null | {
"abstract": " We use the empirical normalized (smoothed) periodogram of a $S\\alpha S$\nmoving average random function to estimate its kernel function from high\nfrequency observation data. The weak consistency of the estimator is shown. A\nsimulation study of the performance of the estimates rounds up the paper.\n",
"title": "Nonparametric estimation of the kernel function of symmetric stable moving average random functions"
} | null | null | null | null | true | null | 18268 | null | Default | null | null |
null | {
"abstract": " Ultracold atomic Fermi gases in two-dimensions (2D) are an increasingly\npopular topic of research. The interaction strength between spin-up and\nspin-down particles in two-component Fermi gases can be tuned in experiments,\nallowing for a strongly interacting regime where the gas properties are yet to\nbe fully understood. We have probed this regime for 2D Fermi gases by\nperforming T=0 ab initio diffusion Monte Carlo calculations. The many-body\ndynamics are largely dependent on the two-body interactions, therefore we start\nwith an in-depth look at scattering theory in 2D. We show the partial-wave\nexpansion and its relation to the scattering length and effective range. Then\nwe discuss our numerical methods for determining these scattering parameters.\nWe close out this discussion by illustrating the details of bound states in 2D.\nTransitioning to the many-body system, we use variationally optimized wave\nfunctions to calculate ground-state properties of the gas over a range of\ninteraction strengths. We show results for the energy per particle and\nparametrize an equation of state. We then proceed to determine the chemical\npotential for the strongly interacting gas.\n",
"title": "Fermions in Two Dimensions: Scattering and Many-Body Properties"
} | null | null | null | null | true | null | 18269 | null | Default | null | null |
null | {
"abstract": " In this paper, instead of the usual Gaussian noise assumption,\n$t$-distribution noise is assumed. A Maximum Likelihood Estimator using the\nmost recent N measurements is proposed for the Auto-Regressive-Moving-Average\nwith eXogenous input (ARMAX) process with this assumption. The proposed\nestimator is robust to outliers because the `thick tail' of the t-distribution\nreduces the effect of large errors in the likelihood function. Instead of\nsolving the resulting nonlinear estimator numerically, the Influence Function\nis used to formulate a computationally efficient recursive solution, which\nreduces to the traditional Moving Horizon Estimator when the noise is Gaussian.\nThe formula for the variance of the estimate is derived. This formula shows\nexplicitly how the variance of the estimate is affected by the number of\nmeasurements and noise variance. The simulation results show that the proposed\nestimator has smaller variance and is more robust to outliers than the Moving\nWindow Least-Squares Estimator. For the same accuracy, the proposed estimator\nis an order of magnitude faster than the particle filter.\n",
"title": "Moving Horizon Estimation for ARMAX process with t-Distribution Noise"
} | null | null | null | null | true | null | 18270 | null | Default | null | null |
null | {
"abstract": " Complex spatiotemporal patterns, called chimera states, consist of coexisting\ncoherent and incoherent domains and can be observed in networks of coupled\noscillators. The interplay of synchrony and asynchrony in complex brain\nnetworks is an important aspect in studies of both brain function and disease.\nWe analyse the collective dynamics of FitzHugh-Nagumo neurons in complex\nnetworks motivated by its potential application to epileptology and epilepsy\nsurgery. We compare two topologies: an empirical structural neural connectivity\nderived from diffusion-weighted magnetic resonance imaging and a mathematically\nconstructed network with modular fractal connectivity. We analyse the\nproperties of chimeras and partially synchronized states, and obtain regions of\ntheir stability in the parameter planes. Furthermore, we qualitatively simulate\nthe dynamics of epileptic seizures and study the influence of the removal of\nnodes on the network synchronizability, which can be useful for applications to\nepileptic surgery.\n",
"title": "Chimera states in brain networks: empirical neural vs. modular fractal connectivity"
} | null | null | null | null | true | null | 18271 | null | Default | null | null |
null | {
"abstract": " The estimation of unknown values of parameters (or hidden variables, control\nvariables) that characterise a physical system often relies on the comparison\nof measured data with synthetic data produced by some numerical simulator of\nthe system as the parameter values are varied. This process often encounters\ntwo major difficulties: the generation of synthetic data for each considered\nset of parameter values can be computationally expensive if the system model is\ncomplicated; and the exploration of the parameter space can be inefficient\nand/or incomplete, a typical example being when the exploration becomes trapped\nin a local optimum of the objection function that characterises the mismatch\nbetween the measured and synthetic data. A method to address both these issues\nis presented, whereby: a surrogate model (or proxy), which emulates the\ncomputationally expensive system simulator, is constructed using deep recurrent\nnetworks (DRN); and a nested sampling (NS) algorithm is employed to perform\nefficient and robust exploration of the parameter space. The analysis is\nperformed in a Bayesian context, in which the samples characterise the full\njoint posterior distribution of the parameters, from which parameter estimates\nand uncertainties are easily derived. The proposed approach is compared with\nconventional methods in some numerical examples, for which the results\ndemonstrate that one can accelerate the parameter estimation process by at\nleast an order of magnitude.\n",
"title": "Bayesian surrogate learning in dynamic simulator-based regression problems"
} | null | null | [
"Computer Science",
"Statistics"
]
| null | true | null | 18272 | null | Validated | null | null |
null | {
"abstract": " We address the boundary value problem for the ellipsoidal BGK model of the\nBoltzmann equation posed in a bounded interval. The existence of a unique mild\nsolution is established under the assumption that the inflow boundary data does\nnot concentrate too much around the zero velocity, and the gas is sufficiently\nrarefied.\n",
"title": "Stationary solutions for the ellipsoidal BGK model in a slab"
} | null | null | [
"Mathematics"
]
| null | true | null | 18273 | null | Validated | null | null |
null | {
"abstract": " Octahedral tilting is most common distortion process observed in\ncentrosymmetric perovskite compounds (ABO$_{3}$). Indeed, crucial physical\nproperties of this oxide stem from the tilts of BO$_{6}$ rigid octahedra. In\nmicrowave ceramics with perovskite-type structure, there is a close relation\nbetween the temperature coefficient of resonant frequency and tilt system of\nthe perovskite structure. However, in many cases, limited access facilities are\nneeded to assign correctly the space group, including neutron scattering and\ntransmission electron microscopy. Here, we combine the Raman scattering and\ngroup-theory calculations to probe the structural distortion in the perovskite\n(Ba$_{1-x}$Sr$_{x}$)$_{3}$CaNb$_{2}$O$_{9}$ solid solution, which exhibits a\nstructural phase transition at $x$ $\\geq$ 0.7, from D$_{3d}^{3}$ trigonal to\nC$_{2h}^{3}$ monoclinic cell. Both phases are related by an octahedral tilting\ndistortion ($a^{0}b^{-}b^{-}$ in Glazer notation). Low temperature Raman\nspectra corroborate the group-theoretical predictions for\nSr$_{3}$CaNb$_{2}$O$_{9}$ compound, since 36 modes detected at 25 K agree well\nwith those 42 (25A$_{g}$ $\\oplus$ 17B$_{g}$) predicted ones.\n",
"title": "Raman signatures of monoclinic distortion in (Ba$_{1-x}$Sr$_{x}$)$_{3}$CaNb$_{2}$O$_{9}$ complex perovskites"
} | null | null | null | null | true | null | 18274 | null | Default | null | null |
null | {
"abstract": " Elastic weight consolidation (EWC, Kirkpatrick et al, 2017) is a novel\nalgorithm designed to safeguard against catastrophic forgetting in neural\nnetworks. EWC can be seen as an approximation to Laplace propagation (Eskin et\nal, 2004), and this view is consistent with the motivation given by Kirkpatrick\net al (2017). In this note, I present an extended derivation that covers the\ncase when there are more than two tasks. I show that the quadratic penalties in\nEWC are inconsistent with this derivation and might lead to double-counting\ndata from earlier tasks.\n",
"title": "On Quadratic Penalties in Elastic Weight Consolidation"
} | null | null | null | null | true | null | 18275 | null | Default | null | null |
null | {
"abstract": " Following the decision to reduce the L* from 4.4 m to 4.1 m, the BeamCal had\nto be moved closer to the interaction point. Results of a study of how this\naffects the beamstrahlung and backward scattering backgrounds show that the\ne+e- pair background depositions from beamstrahlung at the BeamCal rises by\n20%. The background from backscattered electrons and positrons in the inner\npixel layers rises almost by a factor two, so does the number of photons in the\ntracker.\n",
"title": "The design of the ILD forward region"
} | null | null | null | null | true | null | 18276 | null | Default | null | null |
null | {
"abstract": " Transition metal oxide memristors, or resistive random-access memory (RRAM)\nswitches, are under intense development for storage-class memory because of\ntheir favorable operating power, endurance, speed, and density. Their\ncommercial deployment critically depends on predictive compact models based on\nunderstanding nanoscale physico-chemical forces, which remains elusive and\ncontroversial owing to the difficulties in directly observing atomic motions\nduring resistive switching, Here, using scanning transmission synchrotron x-ray\nspectromicroscopy to study in-situ switching of hafnium oxide memristors, we\ndirectly observed the formation of a localized oxygen-deficiency-derived\nconductive channel surrounded by a low-conductivity ring of excess oxygen.\nSubsequent thermal annealing homogenized the segregated oxygen, resetting the\ncells towards their as-grown resistance state. We show that the formation and\ndissolution of the conduction channel are successfully modeled by radial\nthermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This\nconfirmation and quantification of two opposing nanoscale radial forces that\naffect bipolar memristor switching are important components for any future\nphysics-based compact model for the electronic switching of these devices.\n",
"title": "Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors"
} | null | null | null | null | true | null | 18277 | null | Default | null | null |
null | {
"abstract": " In this paper, deep neural network (DNN) is utilized to improve the belief\npropagation (BP) detection for massive multiple-input multiple-output (MIMO)\nsystems. A neural network architecture suitable for detection task is firstly\nintroduced by unfolding BP algorithms. DNN MIMO detectors are then proposed\nbased on two modified BP detectors, damped BP and max-sum BP. The correction\nfactors in these algorithms are optimized through deep learning techniques,\naiming at improved detection performance. Numerical results are presented to\ndemonstrate the performance of the DNN detectors in comparison with various BP\nmodifications. The neural network is trained once and can be used for multiple\nonline detections. The results show that, compared to other state-of-the-art\ndetectors, the DNN detectors can achieve lower bit error rate (BER) with\nimproved robustness against various antenna configurations and channel\nconditions at the same level of complexity.\n",
"title": "Improving Massive MIMO Belief Propagation Detector with Deep Neural Network"
} | null | null | null | null | true | null | 18278 | null | Default | null | null |
null | {
"abstract": " As program comprehension is a vast research area, it is necessary to get an\noverview of its rising and falling trends. We performed an n-gram frequency\nanalysis on titles, abstracts and keywords of 1885 articles about program\ncomprehension from the years 2000-2014. According to this analysis, the most\nrising trends are feature location and open source systems, the most falling\nones are program slicing and legacy systems.\n",
"title": "Trend Analysis on the Metadata of Program Comprehension Papers"
} | null | null | null | null | true | null | 18279 | null | Default | null | null |
null | {
"abstract": " The so-called binary perfect phylogeny with persistent characters has\nrecently been thoroughly studied in computational biology as it is less\nrestrictive than the well known binary perfect phylogeny. Here, we focus on the\nnotion of (binary) persistent characters, i.e. characters that can be realized\non a phylogenetic tree by at most one $0 \\rightarrow 1$ transition followed by\nat most one $1 \\rightarrow 0$ transition in the tree, and analyze these\ncharacters under different aspects. First, we illustrate the connection between\npersistent characters and Maximum Parsimony, where we characterize persistent\ncharacters in terms of the first phase of the famous Fitch algorithm.\nAfterwards we focus on the number of persistent characters for a given\nphylogenetic tree. We show that this number solely depends on the balance of\nthe tree. To be precise, we develop a formula for counting the number of\npersistent characters for a given phylogenetic tree based on an index of tree\nbalance, namely the Sackin index. Lastly, we consider the question of how many\n(carefully chosen) binary characters together with their persistence status are\nneeded to uniquely determine a phylogenetic tree and provide an upper bound for\nthe number of characters needed.\n",
"title": "Combinatorial views on persistent characters in phylogenetics"
} | null | null | null | null | true | null | 18280 | null | Default | null | null |
null | {
"abstract": " We develop a uniform asymptotic expansion for the empirical distribution\nfunction of residuals in the nonparametric IV regression. Such expansion opens\na door for construction of a broad range of residual-based specification tests\nin nonparametric IV models. Building on obtained result, we develop a test for\nthe separability of unobservables in econometric models with endogeneity. The\ntest is based on verifying the independence condition between residuals of the\nNPIV estimator and the instrument and can distinguish between the non-separable\nand the separable specification under endogeneity.\n",
"title": "Distribution of residuals in the nonparametric IV model with application to separability testing"
} | null | null | [
"Mathematics",
"Statistics"
]
| null | true | null | 18281 | null | Validated | null | null |
null | {
"abstract": " Understanding a visual scene goes beyond recognizing individual objects in\nisolation. Relationships between objects also constitute rich semantic\ninformation about the scene. In this work, we explicitly model the objects and\ntheir relationships using scene graphs, a visually-grounded graphical structure\nof an image. We propose a novel end-to-end model that generates such structured\nscene representation from an input image. The model solves the scene graph\ninference problem using standard RNNs and learns to iteratively improves its\npredictions via message passing. Our joint inference model can take advantage\nof contextual cues to make better predictions on objects and their\nrelationships. The experiments show that our model significantly outperforms\nprevious methods for generating scene graphs using Visual Genome dataset and\ninferring support relations with NYU Depth v2 dataset.\n",
"title": "Scene Graph Generation by Iterative Message Passing"
} | null | null | null | null | true | null | 18282 | null | Default | null | null |
null | {
"abstract": " We investigate the apparent power-law scaling of the pseudo phase space\ndensity (PPSD) in CDM halos. We study fluid collapse, using the close analogy\nbetween the gas entropy and the PPSD in the fluid approximation. Our\nhydrodynamic calculations allow for a precise evaluation of logarithmic\nderivatives. For scale-free initial conditions, entropy is a power law in\nLagrangian (mass) coordinates, but not in Eulerian (radial) coordinates. The\ndeviation from a radial power law arises from incomplete hydrostatic\nequilibrium (HSE), linked to bulk inflow and mass accretion, and the\nconvergence to the asymptotic central power-law slope is very slow. For more\nrealistic collapse, entropy is not a power law with either radius or mass due\nto deviations from HSE and scale-dependent initial conditions. Instead, it is a\nslowly rolling power law that appears approximately linear on a log-log plot.\nOur fluid calculations recover PPSD power-law slopes and residual amplitudes\nsimilar to N-body simulations, indicating that deviations from a power law are\nnot numerical artefacts. In addition, we find that realistic collapse is not\nself-similar: scale lengths such as the shock radius and the turnaround radius\nare not power-law functions of time. We therefore argue that the apparent\npower-law PPSD cannot be used to make detailed dynamical inferences or\nextrapolate halo profiles inward, and that it does not indicate any hidden\nintegrals of motion. We also suggest that the apparent agreement between the\nPPSD and the asymptotic Bertschinger slope is purely coincidental.\n",
"title": "On the Apparent Power Law in CDM Halo Pseudo Phase Space Density Profiles"
} | null | null | null | null | true | null | 18283 | null | Default | null | null |
null | {
"abstract": " The aim of this paper is to present some results relating the properties of\nstability, concentration and approximation to the identity of convolution\nthrough not necessarily mollification type families of heavy tailed Markov\nkernels. A particular case is provided by the kernels $K_t$ obtained as the $t$\nmollification of $L^{\\sigma(t)}$ selected from the family\n$\\mathcal{L}=\\{L^{\\sigma}:\n\\widehat{L^{\\sigma}}(\\xi)=e^{-|\\xi|^\\sigma},0<\\sigma<2\\}$, by a given function\n$\\sigma$ with values in the interval $(0,2)$. We show that a basic Harnack type\ninequality, introduced by C.~Calderón in the convolution case, becomes at\nonce natural to the setting and useful to connect the concepts of stability,\nconcentration and approximation of the identity. Some of the general results\nare extended to spaces of homogeneous type since most of the concepts involved\nin the theory are given in terms of metric and measure.\n",
"title": "Heavy tailed approximate identities and $σ$-stable Markov kernels"
} | null | null | null | null | true | null | 18284 | null | Default | null | null |
null | {
"abstract": " We study dynamical properties of the one- and two-dimensional Falicov-Kimball\nmodel using lattice Monte Carlo simulations. In particular, we calculate the\nspreading of charge correlations in the equilibrium model and after an\ninteraction quench. The results show a reduction of the light-cone velocity\nwith interaction strength at low temperature, while the phase velocity\nincreases. At higher temperature, the initial spreading is determined by the\nFermi velocity of the noninteracting system and the maximum range of the\ncorrelations decreases with increasing interaction strength. Charge order\ncorrelations in the disorder potential enhance the range of the correlations.\nWe also use the numerically exact lattice Monte Carlo results to benchmark the\naccuracy of equilibrium and nonequilibrium dynamical cluster approximation\ncalculations. It is shown that the bias introduced by the mapping to a\nperiodized cluster is substantial, and that from a numerical point of view, it\nis more efficient to simulate the lattice model directly.\n",
"title": "Spreading of correlations in the Falicov-Kimball model"
} | null | null | null | null | true | null | 18285 | null | Default | null | null |
null | {
"abstract": " We propose a direct estimation method for Rényi and f-divergence measures\nbased on a new graph theoretical interpretation. Suppose that we are given two\nsample sets $X$ and $Y$, respectively with $N$ and $M$ samples, where\n$\\eta:=M/N$ is a constant value. Considering the $k$-nearest neighbor ($k$-NN)\ngraph of $Y$ in the joint data set $(X,Y)$, we show that the average powered\nratio of the number of $X$ points to the number of $Y$ points among all $k$-NN\npoints is proportional to Rényi divergence of $X$ and $Y$ densities. A\nsimilar method can also be used to estimate f-divergence measures. We derive\nbias and variance rates, and show that for the class of $\\gamma$-Hölder\nsmooth functions, the estimator achieves the MSE rate of\n$O(N^{-2\\gamma/(\\gamma+d)})$. Furthermore, by using a weighted ensemble\nestimation technique, for density functions with continuous and bounded\nderivatives of up to the order $d$, and some extra conditions at the support\nset boundary, we derive an ensemble estimator that achieves the parametric MSE\nrate of $O(1/N)$. Our estimators are more computationally tractable than other\ncompeting estimators, which makes them appealing in many practical\napplications.\n",
"title": "Direct Estimation of Information Divergence Using Nearest Neighbor Ratios"
} | null | null | null | null | true | null | 18286 | null | Default | null | null |
null | {
"abstract": " Mixtures of Mallows models are a popular generative model for ranking data\ncoming from a heterogeneous population. They have a variety of applications\nincluding social choice, recommendation systems and natural language\nprocessing. Here we give the first polynomial time algorithm for provably\nlearning the parameters of a mixture of Mallows models with any constant number\nof components. Prior to our work, only the two component case had been settled.\nOur analysis revolves around a determinantal identity of Zagier which was\nproven in the context of mathematical physics, which we use to show polynomial\nidentifiability and ultimately to construct test functions to peel off one\ncomponent at a time.\nTo complement our upper bounds, we show information-theoretic lower bounds on\nthe sample complexity as well as lower bounds against restricted families of\nalgorithms that make only local queries. Together, these results demonstrate\nvarious impediments to improving the dependence on the number of components.\nThey also motivate the study of learning mixtures of Mallows models from the\nperspective of beyond worst-case analysis. In this direction, we show that when\nthe scaling parameters of the Mallows models have separation, there are much\nfaster learning algorithms.\n",
"title": "Efficiently Learning Mixtures of Mallows Models"
} | null | null | null | null | true | null | 18287 | null | Default | null | null |
null | {
"abstract": " Optimal scheduling of hydrogen production in dynamic pricing power market can\nmaximize the profit of hydrogen producer; however, it highly depends on the\naccurate forecast of hydrogen consumption. In this paper, we propose a deep\nleaning based forecasting approach for predicting hydrogen consumption of fuel\ncell vehicles in future taxi industry. The cost of hydrogen production is\nminimized by utilizing the proposed forecasting tool to reduce the hydrogen\nproduced during high cost on-peak hours and guide hydrogen producer to store\nsufficient hydrogen during low cost off-peak hours.\n",
"title": "Optimal Scheduling of Electrolyzer in Power Market with Dynamic Prices"
} | null | null | null | null | true | null | 18288 | null | Default | null | null |
null | {
"abstract": " A modified AC method based on micro-fabricated heater and resistive\nthermometers has been applied to measure the thermopower of microscale samples.\nA sinusoidal current with frequency {\\omega} is passed to the heater to\ngenerate an oscillatory temperature difference across the sample at a frequency\n2{\\omega}, which simultaneously induces an AC thermoelectric voltage, also at\nthe frequency 2{\\omega}. A key step of the method is to extract amplitude and\nphase of the oscillatory temperature difference by probing the AC temperature\nvariation at each individual thermometer. The sign of the thermopower is\ndetermined by examining the phase difference between the oscillatory\ntemperature difference and the AC thermoelectric voltage. The technique has\nbeen compared with the popular DC method by testing both n-type and p-type thin\nfilm samples. Both methods yielded consistent results, which verified the\nreliability of the newly proposed AC method.\n",
"title": "Determination of the thermopower of microscale samples with an AC method"
} | null | null | null | null | true | null | 18289 | null | Default | null | null |
null | {
"abstract": " This project explores public opinion on the Supplemental Nutrition Assistance\nProgram (SNAP) in news and social media outlets, and tracks elected\nrepresentatives' voting records on issues relating to SNAP and food insecurity.\nWe used machine learning, sentiment analysis, and text mining to analyze\nnational and state level coverage of SNAP in order to gauge perceptions of the\nprogram over time across these outlets. Results indicate that the majority of\nnews coverage has negative sentiment, more partisan news outlets have more\nextreme sentiment, and that clustering of negative reporting on SNAP occurs in\nthe Midwest. Our final results and tools will be displayed in an on-line\napplication that the ACFB Advocacy team can use to inform their communication\nto relevant stakeholders.\n",
"title": "Food for Thought: Analyzing Public Opinion on the Supplemental Nutrition Assistance Program"
} | null | null | null | null | true | null | 18290 | null | Default | null | null |
null | {
"abstract": " Let $P(n)$ be the set of all posets with $n$ elements and $NIP(n)$ the set of\nnon-isomorphic posets with $n$ elements. Let $P^{(j)}(n)$, $1\\leq j\\leq 2^n,$\nbe the number of all posets with $n$ elements possessing exactly $j$\nantichains. We have determined the numbers $P^{(j)}(7),$ $1\\leq j\\leq 128$, and\nusing a result of M. Erné \\cite{EM4}, we compute $|P(10)|$ without the aid of\nany computer program. We include the Hasse diagrams of all the non-isomorphic\nposets of $P(7)$.\n",
"title": "Hasse diagrams of non-isomorphic posets with $n$ elements, $2\\leq n \\leq 7,$ and the number of posets with $10$ elements, without the aid of any computer program"
} | null | null | null | null | true | null | 18291 | null | Default | null | null |
null | {
"abstract": " Advancement in technology has generated abundant high-dimensional data that\nallows integration of multiple relevant studies. Due to their huge\ncomputational advantage, variable screening methods based on marginal\ncorrelation have become promising alternatives to the popular regularization\nmethods for variable selection. However, all these screening methods are\nlimited to single study so far. In this paper, we consider a general framework\nfor variable screening with multiple related studies, and further propose a\nnovel two-step screening procedure using a self-normalized estimator for\nhigh-dimensional regression analysis in this framework. Compared to the\none-step procedure and rank-based sure independence screening (SIS) procedure,\nour procedure greatly reduces false negative errors while keeping a low false\npositive rate. Theoretically, we show that our procedure possesses the sure\nscreening property with weaker assumptions on signal strengths and allows the\nnumber of features to grow at an exponential rate of the sample size. In\naddition, we relax the commonly used normality assumption and allow\nsub-Gaussian distributions. Simulations and a real transcriptomic application\nillustrate the advantage of our method as compared to the rank-based SIS\nmethod.\n",
"title": "Variable screening with multiple studies"
} | null | null | null | null | true | null | 18292 | null | Default | null | null |
null | {
"abstract": " Neural models, in particular the d-vector and x-vector architectures, have\nproduced state-of-the-art performance on many speaker verification tasks.\nHowever, two potential problems of these neural models deserve more\ninvestigation. Firstly, both models suffer from `information leak', which means\nthat some parameters participating in model training will be discarded during\ninference, i.e, the layers that are used as the classifier. Secondly, both\nmodels do not regulate the distribution of the derived speaker vectors. This\n`unconstrained distribution' may degrade the performance of the subsequent\nscoring component, e.g., PLDA. This paper proposes a Gaussian-constrained\ntraining approach that (1) discards the parametric classifier, and (2) enforces\nthe distribution of the derived speaker vectors to be Gaussian. Our experiments\non the VoxCeleb and SITW databases demonstrated that this new training approach\nproduced more representative and regular speaker embeddings, leading to\nconsistent performance improvement.\n",
"title": "Gaussian-Constrained training for speaker verification"
} | null | null | null | null | true | null | 18293 | null | Default | null | null |
null | {
"abstract": " Methods for detecting structural changes, or change points, in time series\ndata are widely used in many fields of science and engineering. This chapter\nsketches some basic methods for the analysis of structural changes in time\nseries data. The exposition is confined to retrospective methods for univariate\ntime series. Several recent methods for dating structural changes are compared\nusing a time series of oil prices spanning more than 60 years. The methods\nbroadly agree for the first part of the series up to the mid-1980s, for which\nchanges are associated with major historical events, but provide somewhat\ndifferent solutions thereafter, reflecting a gradual increase in oil prices\nthat is not well described by a step function. As a further illustration, 1990s\ndata on the volatility of the Hang Seng stock market index are reanalyzed.\n",
"title": "Structural Change in (Economic) Time Series"
} | null | null | [
"Physics",
"Statistics"
]
| null | true | null | 18294 | null | Validated | null | null |
null | {
"abstract": " Statecharts are frequently used as a modeling formalism in the design of\nstate-based systems. Formal verification techniques are also often applied to\nprove certain properties about the behavior of the system. One of the most\nefficient techniques for formal verification is Counterexample-Guided\nAbstraction Refinement (CEGAR), which reduces the complexity of systems by\nautomatically building and refining abstractions. In our paper we present a\nnovel adaptation of the CEGAR approach to hierarchical statechart models. First\nwe introduce an encoding of the statechart to logical formulas that preserves\ninformation about the state hierarchy. Based on this encoding we propose\nabstraction and refinement techniques that utilize the hierarchical structure\nof statecharts and also handle variables in the model. The encoding allows us\nto use SMT solvers for the systematic exploration and verification of the\nabstract model, including also bounded model checking. We demonstrate the\napplicability and efficiency of our abstraction techniques with measurements on\nan industry-motivated example.\n",
"title": "Exploiting Hierarchy in the Abstraction-Based Verification of Statecharts Using SMT Solvers"
} | null | null | null | null | true | null | 18295 | null | Default | null | null |
null | {
"abstract": " Recently the dynamics of signed networks, where the ties among the agents can\nbe both positive (attractive) or negative (repulsive) have attracted\nsubstantial attention of the research community. Examples of such networks are\nmodels of opinion dynamics over signed graphs, recently introduced by Altafini\n(2012,2013) and extended to discrete-time case by Meng et al. (2014). It has\nbeen shown that under mild connectivity assumptions these protocols provide the\nconvergence of opinions in absolute value, whereas their signs may differ. This\n\"modulus consensus\" may correspond to the polarization of the opinions (or\nbipartite consensus, including the usual consensus as a special case), or their\nconvergence to zero. In this paper, we demonstrate that the phenomenon of\nmodulus consensus in the discrete-time Altafini model is a manifestation of a\nmore general and profound fact, regarding the solutions of a special recurrent\ninequality. Although such a recurrent inequality does not provide the\nuniqueness of a solution, it can be shown that, under some natural assumptions,\neach of its bounded solutions has a limit and, moreover, converges to\nconsensus. A similar property has previously been established for special\ncontinuous-time differential inequalities (Proskurnikov, Cao, 2016). Besides\nanalysis of signed networks, we link the consensus properties of recurrent\ninequalities to the convergence analysis of distributed optimization algorithms\nand the problems of Schur stability of substochastic matrices.\n",
"title": "Modulus consensus in discrete-time signed networks and properties of special recurrent inequalities"
} | null | null | null | null | true | null | 18296 | null | Default | null | null |
null | {
"abstract": " Stagnation of grain growth is often attributed to impurity segregation.\nYttria-stabilized cubic zirconia does not evidence any segregation-induced\nslowdown, as its grain growth obeys the parabolic law when the grain size\nincreases by more than one order of magnitude. However, lowering the\ntemperature below 1300 oC triggers an abrupt slowdown, constraining the average\ngrains to grow by less than 0.5 ${\\mu}$m in 1000 h despite a relatively large\ndriving force imparted in the fine grains of ~0.5 ${\\mu}$m. Yet isolated\npockets of abnormally large grains, along with pockets of abnormally small\ngrains, emerge in the same latter sample. Such microstructure bifurcation has\nnever been observed before, and can only be explained by an inhomogeneous\ndistribution of immobile four-grain junctions. The implications of these\nfindings for two-step sintering are discussed.\n",
"title": "Mobility Transition at Grain Boundaries in Two-Step Sintered 8 mol% Yttria Stabilized Zirconia"
} | null | null | null | null | true | null | 18297 | null | Default | null | null |
null | {
"abstract": " We present three natural combinatorial properties for class forcing notions,\nwhich imply the forcing theorem to hold. We then show that all known sufficent\nconditions for the forcing theorem (except for the forcing theorem itself),\nincluding the three properties presented in this paper, imply yet another\nregularity property for class forcing notions, namely that proper classes of\nthe ground model cannot become sets in a generic extension, that is they do not\nhave set-sized names in the ground model. We then show that over certain models\nof Gödel-Bernays set theory without the power set axiom, there is a notion of\nclass forcing which turns a proper class into a set, however does not satisfy\nthe forcing theorem. Moreover, we show that the property of not turning proper\nclasses into sets can be used to characterize pretameness over such models of\nGödel-Bernays set theory.\n",
"title": "Sufficient conditions for the forcing theorem, and turning proper classes into sets"
} | null | null | null | null | true | null | 18298 | null | Default | null | null |
null | {
"abstract": " We study the Cauchy problem for effectively hyperbolic operators $P$ with\nprincipal symbol $p(t, x,\\tau,\\xi)$ having triple characteristics on $t = 0$.\nUnder a condition (E) we show that such operators are strongly hyperbolic, that\nis the Cauchy problem is well posed for $p(t, x,D_t, D_x) + Q(t, x, D_t, D_x)$\nwith arbitrary lower order term $Q$. The proof is based on energy estimates\nwith weight $t^{-N}$ for a first order pseudo-differential system, where $N$\ndepends on lower order terms. For our analysis we construct a non-negative\ndefinite symmetrizer $S(t)$ and we prove a version of Fefferman-Phong type\ninequality for ${\\rm Re}\\, (S(t)U, U)_{L^2({\\mathbb R}^n)}$ with a lower bound\n$-C t^{-1}\\|\\langle D \\rangle^{-1}U\\|_{L^2(\\mathbb R^n)}$.\n",
"title": "Cauchy problem for effectively hyperbolic operators with triple characteristics"
} | null | null | null | null | true | null | 18299 | null | Default | null | null |
null | {
"abstract": " The uniform electron gas at finite temperature is of high current interest\nfor warm dense matter research. The complicated interplay of quantum degeneracy\nand Coulomb coupling effects is fully contained in the pair distribution\nfunction or, equivalently, the static strucutre factor. By combining exact\nquantum Monte Carlo results for large wave vectors with the long-range behavior\nfrom the Singwi-Tosi-Land-Sjölander approximation, we are able to obtain\nhighly accurate data for the static structure factor over the entire $k$-range.\nThis allows us to gauge the accuracy of previous approximations and discuss\ntheir respective shortcomings. Further, our new data will serve as valuable\ninput for the computation of other quantities.\n",
"title": "\\textit{Ab Initio} results for the Static Structure Factor of the Warm Dense Electron Gas"
} | null | null | [
"Physics"
]
| null | true | null | 18300 | null | Validated | null | null |
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