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The geography of introgression in a patchy environment and the thorn in the side of ecological speciation

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Current Zoology 2013年第1期59卷 72-86页

作者： Nicolas BIERNE Pierre-alexandre GAGNAIRE Patrice DAVID Universit6 Montpellier 2 Place Eugene Bataillon 34095 Montpellier Cedex 5 France ISEM - CNRS UMR 5554 SMEL 2 rue des Chantiers 34200 S6te France CEFE - CNRS UMR 5175 34293 MontpeUier Cedex 5 France

When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic structure of selected traits/loci tends to coincide with habitat variables （producing Genetic-Environment Association or GEA）, genetic differentiation at neutral loci unlinked to any selected locus rather depends on geographic connectivity at a large scale （e.g. Isolation- By-Distance or IBD）, although these loci often display GEA at a small scale. This discrepancy has been repeatedly taken as evi- dence for parallel primary divergence driven by local adaptation. We argue that this interpretation needs to be addressed more thoroughly by considering the alternative hypothesis that speciation was initiated in allopatry and secondary introgression has subsequently erased the signal of past differentiation at neutral loci. We present a model of neutral introgression after secondary contact in a mosaic hybrid zone, which describes how GEAs dissipate with time and how neutral variation self-organizes accord- ing to the environmental and geographic structures. We show that although neutral loci can be affected by environmental selection they are often more affected by history and connectivity： the neutral structure retains the initial geographic separation more than it correlates with the environment during the colonization and introgression phases, and then converges to a migration-drift balance, the most frequent outcome of which is GEA at a local scale but IBD at a large scale. This is the exact pattern usually attributed to parallel ecological speciation. Introgression is heterogeneous in space and depends on the landscape structure （e.g. it is faster in small patches, which are more impacted by immigration）. Furthermore, there is no directionality in the association and it is possi- ble to observe reversed GEAs between distant regions. We argue that the his

关键词： Ecological speciation Local adaptation Mosaic hybrid zone Reproductive isolation Genetic-environment association

Detecting polygenic selection in marine populations by combining population genomics and quantitative genetics approaches

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Current Zoology 2016年第6期62卷 603-616页

作者： Pierre-alexandre GAGNAIRE Oscar E. GAGGIOTTI Universite Montpellier 2 Place Eugene Bataillon 34095 Montpellier Cedex 5 France ISEM - CNRS UMR 5554 SMEL 2 rue des Chantiers Sete 34200 France Scottish Oceans Institute University of St Andrews East Sands St Andrews KY16 9LB UK

Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, efficient selection fueled by frequent adaptive mutations, and high migration loads. This has important consequences for understanding how local adaptation proceeds in the sea. A key issue in this regard, relates to the genetic architecture underlying fitness traits. Theory predicts that adaptation may involve many genes but with a high variance in effect size. Therefore, the effect of selection on allele frequencies may be substantial for the largest effect size loci, but insignificant for small effect genes. In such a context, the performance of population genomic methods to unravel the genetic basis of adaptation depends on the fraction of adaptive genetic variance explained by the cumulative effect of outlier loci. Here, we address some methodological challenges associated with the detection of local adaptation using molecular approaches. We provide an overview of genome scan methods to detect selection, including those assuming complex demographic models that better describe spatial population structure. We then focus on quantitative genetics approaches that search for genotype-phenotype associations at different genomic scales, including genome-wide methods evaluating the cumulative effect of variants. We argue that the limited power of single locus tests can be alleviated by the use of polygenic scores to estimate the joint contribution of candidate variants to phenotypic variation.

关键词： local adaptation genome scans quantitative genetics genotype-phenotype association polygenic scores.

Characteristics of lightning‐induced voltages based on experimental data

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High Voltage 2021年第3期6卷 555-561页

作者： Michele N.N.Santos alexandre Piantini Technological and Exact Sciences Department Federal University of AmapáMacapá‐APBrazil Institute of Energy and Environment University of São PauloSão Paulo‐SPBrazil

This paper presents an analysis of 64 lightning‐induced voltage waveforms recorded in an experimental system implemented in the campus of the University of São Paulo,*** voltages were measured on a 10 m high,2.7 km long un‐energized overhead line consisting of two conductors installed on 6 m *** of the conductors had surge arresters,while the other one was left *** speaking,all the recorded voltages on the unprotected conductor were bipolar,but in many cases only one semi‐cycle could be considered important for practical *** criteria are discussed for the determination of the waveshape parameters,which may differ signifi-cantly from those of the standard lightning impulse voltage(1.2/50μs).Based on the proposed criterion for classifying the induced voltages,unipolar waveforms accounted for 67%of the total and,except for one case,all of them had positive *** median values of the front time and time‐to‐half‐value were,respectively,5.2μs and 15.8μ*** waveforms were 33%of the total and in approximately 62%of the cases the first semi‐cycle was of positive *** 91%of the cases the voltage peak occurred either in the first or the second semi‐cycle.

关键词： lightning bipolar protected

On the Numerical Solution of Some Eikonal Equations:An Elliptic Solver Approach

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Chinese Annals of Mathematics,Series B 2015年第5期36卷 689-702页

作者： alexandre CABOUSSAT Roland GLOWINSKI Tsorng-Whay PAN Haute Ecole de Gestion de Genève University of Applied Sciences Department of Mathematics University of Houston

The steady Eikonal equation is a prototypical first-order fully nonlinear equation. A numerical method based on elliptic solvers is presented here to solve two different kinds of steady Eikonal equations and compute solutions, which are maximal and minimal in the variational sense. The approach in this paper relies on a variational argument involving penalty, a biharmonic regularization, and an operator-splitting-based time-discretization scheme for the solution of an associated initial-value problem. This approach allows the decoupling of the nonlinearities and differential *** experiments are performed to validate this approach and investigate its convergence properties from a numerical viewpoint.

关键词： Eikonal equations Maximal solutions Regularization methods Operator slalitting Finite element methods

Saliency-based framework for facial expression recognition

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Frontiers of Computer Science 2019年第1期13卷 183-198页

作者： Rizwan Ahmed KHAN alexandre MEYER Hubert KONIK Saida BOUAKAZ Universite de Lyon CNRSLIRISUMR5205Universite Lyon 1Lyon F-69622France Faculty of Information Technology Barrett Hodgson UniversityKarachi 74900Pakistan Laboratoire Hubert Curien UMR5516Universite Jean MonnetSaint-Etienne 42000France

This article proposes a novel framework for the recognition of six universal facial *** framework is based on three sets of features extracted from a face image:entropy,brightness,and local binary ***, saliency maps are obtained using the state-of-the-art saliency detection algorithm "frequency-tuned salient region detection".The idea is to use saliency maps to determine appropriate weights or values for the extracted features (i.e.,brightness and entropy).We have performed a visual experiment to validate the performance of the saliency detection algorithm against the human visual *** movements of 15 subjects were recorded using an eye-tracker in free-viewing conditions while they watched a collection of 54 videos selected from the Cohn-Kanade facial expression *** results of the visual experiment demonstrated that the obtained saliency maps are consistent with the data on human ***,the performance of the proposed framework is demonstrated via satisfactory classification results achieved with the Cohn-Kanade database,FG-NET FEED database, and Dartmouth database of children's faces.

关键词： facial expression recognition classification salient regions entropy brightness local binary pattern

Learning to synthesize:robust phase retrieval at low photon counts

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Light(Science & Applications) 2020年第1期9卷 1657-1672页

作者： Mo Deng Shuai Li alexandre Goy Iksung Kang George Barbastathis Department of Electrical Engineering and Computer Science Massachusetts Institute of TechnologyCambridgeMA 02139USA Sensebrain Technology Limited LLC 2550 N 1st StreetSuite 300San JoseCA 95131USA Omnisens SA Riond Bosson 31110 MorgesVDSwitzerland Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA Singapore-MIT Alliance for Research and Technology(SMART)Centre Singapore 117543Singapore

The quality of inverse problem solutions obtained through deep learning is limited by the nature of the priors learned from examples presented during the training *** in the case of quantitative phase retrieval,spatial frequencies that are underrepresented in the training database,most often at the high band,tend to be suppressed in the *** hoc solutions have been proposed,such as pre-amplifying the high spatial frequencies in the examples;however,while that strategy improves the resolution,it also leads to high-frequency artefacts,as well as low-frequency distortions in the ***,we present a new approach that learns separately how to handle the two frequency bands,low and high,and learns how to synthesize these two bands into full-band *** show that this“learning to synthesize”(LS)method yields phase reconstructions of high spatial resolution and without artefacts and that it is resilient to high-noise conditions,e.g.,in the case of very low photon *** addition to the problem of quantitative phase retrieval,the LS method is applicable,in principle,to any inverse problem where the forward operator treats different frequency bands unevenly,i.e.,is ill-posed.

关键词： synthesize bands phase

Attempted altruistic infanticide in a context of psychotic decompensation induced by stress linked to the COVID-19 pandemic:a case report

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Forensic Sciences Research 2021年第2期6卷 148-151页

作者： Camille Jantzi alexandre perrin University centre of Legal Medicine(cUrML) University of GenevaGenevaswitzerland

the mediatization of the CoVID-19 pandemic has created a lot of stress leading sometimes to mental health *** present a case of a thirty-year-old woman with no history of psychotic disease but some vulnerabilities and no criminal record,who attempted to kill her seven-year-old son during a brief delusional episode in the context of fear of the *** was successfully treated by pharmacotherapy and *** was examined by forensic psychiatrists leading to the conclusion that her responsibility was highly diminished,and her reoffending risk was *** add to the literature that the CoVID-19 pandemic has been such a stressor for mentally vulnerable people that it could lead to severe psychiatric decompensation and even criminal acts.

关键词： Forensic sciences forensic psychiatry CoVID-19 infanticide psychosis criminal responsibility forensic evaluation

Implicit Sampling,with Application to Data Assimilation

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Chinese Annals of Mathematics,Series B 2013年第1期34卷 89-98页

作者： alexandre J.CHORIN Matthias MORZFELD Xuemin TU Department of Mathematics University of California Lawrence Berkeley National Laboratory Department of Mathematics University of Kansas

There are many computational tasks, in which it is necessary to sample a given probability density function （or pdf for short）, i.e., to use a computer to construct a sequence of independent random vectors x~ （i ---- 1, 2, ~ ~ ~ ）, whose histogram converges to the given pdf. This can be difficult because the sample space can be huge, and more importantly, because the portion of the space, where the density is significant, can be very small, so that one may miss it by an ill-designed sampling scheme. Indeed, Markov- chain Monte Carlo, the most widely used sampling scheme, can be thought of as a search algorithm, where one starts at an arbitrary point and one advances step-by-step towards the high probability region of the space. This can be expensive, in particular because one is typically interested in independent samples, while the chain has a memory. The authors present an alternative, in which samples are found by solving an algebraic equation with a random right-hand side rather than by following a chain; each sample is independent of the previous samples. The construction in the context of numerical integration is explained, and then it is applied to data assimilation.

关键词： Importance sampling Bayesian estimation Particle filter Implicit filter Data assimilation

Specification of dynamic structure discrete event systems using single point encapsulated control functions

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International Journal of Modeling, Simulation, and Scientific Computing 2014年第3期5卷 171-190页

作者： alexandre Muzy Bernard P.Zeigler I3S UMR CNRS 7271 Bio-info team CS 40121—06903 Sophia-Antipolis CedexFrance RTSync Corp 530 Bartow Drive Suite A Sierra Vista AZ 85635United States of America

In Discrete Event System Specification(DEVS),the dynamics of a network is constituted only by the dynamics of its basic *** state of each component is fully *** in the network is fully decentralized to each *** dynamic structure level,DEVS should permit the same level of ***,it is hard to ensure structure consistency while letting all components achieve structure ***,this solution can be complex to *** avoid these difficulties,usual dynamic structure approaches ensure structure consistency allowing structure changes to be done only by the network having newly added dynamics change *** is a safe and simple way to achieve dynamic ***,it should be possible to simply allow components of a network to modify the structure of their network,other components and/or their own structure—without having to modify the usual definition a DEVS *** this manuscript,it is shown that a simple fully decentralized approach is possible while ensuring full modularity and structure consistency.

关键词： Dynamic structure discrete event system specification