Results for "Didier Schwab"

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Comparison of Global Algorithms in Word Sense DisambiguationApr 07 2017This article compares four probabilistic algorithms (global algorithms) for Word Sense Disambiguation (WSD) in terms of the number of scorer calls (local algo- rithm) and the F1 score as determined by a gold-standard scorer. Two algorithms come from the ... More
Sense Vocabulary Compression through the Semantic Knowledge of WordNet for Neural Word Sense DisambiguationMay 14 2019In this article, we tackle the issue of the limited quantity of manually sense annotated corpora for the task of word sense disambiguation, by exploiting the semantic relationships between senses such as synonymy, hypernymy and hyponymy, in order to compress ... More
Improving the Coverage and the Generalization Ability of Neural Word Sense Disambiguation through Hypernymy and Hyponymy RelationshipsNov 02 2018In Word Sense Disambiguation (WSD), the predominant approach generally involves a supervised system trained on sense annotated corpora. The limited quantity of such corpora however restricts the coverage and the performance of these systems. In this article, ... More
Enhancing Translation Language Models with Word Embedding for Information RetrievalJan 11 2018In this paper, we explore the usage of Word Embedding semantic resources for Information Retrieval (IR) task. This embedding, produced by a shallow neural network, have been shown to catch semantic similarities between words (Mikolov et al., 2013). Hence, ... More
Hot subdwarfs formed from the merger of two He white dwarfsMar 01 2018We perform stellar evolution calculations of the remnant of the merger of two He white dwarfs (WDs). Our initial conditions are taken from hydrodynamic simulations of double WD mergers and the viscous disc phase that follows. We evolve these objects from ... More
Persistent current in metals with a large dephasing rateMay 30 2000In a weakly disordered metal electron interactions are responsible for both decoherence of the quasi-particles as well as for quantum corrections to thermodynamic properties. We consider electrons which are interacting with two-level-systems. We show ... More
Système de traduction automatique statistique Anglais-ArabeFeb 06 2018Machine translation (MT) is the process of translating text written in a source language into text in a target language. In this article, we present our English-Arabic statistical machine translation system. First, we present the general process for setting ... More
Deep Investigation of Cross-Language Plagiarism Detection MethodsMay 24 2017This paper is a deep investigation of cross-language plagiarism detection methods on a new recently introduced open dataset, which contains parallel and comparable collections of documents with multiple characteristics (different genres, languages and ... More
Évaluation et consolidation d'un réseau lexical via un outil pour retrouver le mot sur le bout de la langueJan 20 2012Since September 2007, a large scale lexical network for French is under construction through methods based on some kind of popular consensus by means of games (JeuxDeMots project). Human intervention can be considered as marginal. It is limited to corrections, ... More
CompiLIG at SemEval-2017 Task 1: Cross-Language Plagiarism Detection Methods for Semantic Textual SimilarityApr 05 2017We present our submitted systems for Semantic Textual Similarity (STS) Track 4 at SemEval-2017. Given a pair of Spanish-English sentences, each system must estimate their semantic similarity by a score between 0 and 5. In our submission, we use syntax-based, ... More
Coherent transport in disordered metals out of equilibriumJun 13 2001We derive a formula for the quantum corrections to the electrical current for a metal out of equilibrium. In the limit of linear current-voltage characteristics our formula reproduces the well known Altshuler-Aronov correction to the conductivity of a ... More
Quasiclassical theory of charge transport in disordered interacting electron systemsOct 01 2003We consider the corrections to the Boltzmann theory of electrical transport arising from the Coulomb interaction in disordered conductors. In this article the theory is formulated in terms of quasiclassical Green's functions. We demonstrate that the formalism ... More
Landau levels in a topological insulatorJul 05 2011Two recent experiments successfully observed Landau levels in the tunneling spectra of the topological insulator Bi2Se3. To mimic the influence of a scanning tunneling microscope tip on the Landau levels we solve the two-dimensional Dirac equation in ... More
PhoneMD: Learning to Diagnose Parkinson's Disease from Smartphone DataOct 01 2018Nov 14 2018Parkinson's disease is a neurodegenerative disease that can affect a person's movement, speech, dexterity, and cognition. Clinicians primarily diagnose Parkinson's disease by performing a clinical assessment of symptoms. However, misdiagnoses are common. ... More
Min-max formulas for nonlocal elliptic operators on Euclidean spaceDec 23 2018An operator satisfies the Global Comparison Property if anytime a function touches another from above at some point, then the operator preserves the ordering at the point of contact. This is characteristic of degenerate elliptic operators, including nonlocal ... More
Efficient erasure decoding of Reed-Solomon codesJan 14 2009We present a practical algorithm to decode erasures of Reed-Solomon codes over the q elements binary field in O(q \log_2^2 q) time where the constant implied by the O-notation is very small. Asymptotically fast algorithms based on fast polynomial arithmetic ... More
X-ray Timing beyond the Rossi X-ray Timing ExplorerJun 05 2006With its ability to look at bright galactic X-ray sources with sub-millisecond time resolution, the Rossi X-ray Timing Explorer (RXTE) discovered that the X-ray emission from accreting compact stars shows quasi-periodic oscillations on the dynamical timescales ... More
Stability of Inhomogeneous Superstructures from Renormalized Mean-field Theory of the t--J ModelMar 10 2005Apr 16 2005Using the t--J model (which can also include Coulomb repulsion) and the ``plain vanilla'' renormalized mean-field theory of Zhang et al. (1988), stability of inhomogeneous 4a x 4a superstructures as those observed in cuprates superconductors around hole ... More
Investigation of the chiral antiferromagnetic Heisenberg model using PEPSJul 25 2017Sep 19 2017A simple spin-$1/2$ frustrated antiferromagnetic Heisenberg model (AFHM) on the square lattice - including chiral plaquette cyclic terms - was argued [Anne E.B. Nielsen, German Sierra and J. Ignacio Cirac, Nature Communications $\bf 4$, 2864 (2013)] to ... More
Irregular time dependent perturbations of quantum HamiltoniansJan 20 2016Our main goal in this paper is to prove existence (and uniqueness) of the quantum propagator for time dependent quantum Hamiltonians $\hat H(t)$ when this Hamiltonian is perturbed with a quadratic white noise $\dot{\beta}\hat K$. $\beta$ is a continuous ... More
Reclaiming human machine natureSep 29 2014Extending and modifying his domain of life by artifact production is one of the main characteristics of humankind. From the first hominid, who used a wood stick or a stone for extending his upper limbs and augmenting his gesture strength, to current systems ... More
Optimization on linear matrix inequalities for polynomial systems controlSep 12 2013Many problems of systems control theory boil down to solving polynomial equations, polynomial inequalities or polyomial differential equations. Recent advances in convex optimization and real algebraic geometry can be combined to generate approximate ... More
Asymptotics of iterated branching processesOct 03 2005We study the iterated Galton-Watson process (IGW), possibly with thinning, introduced by Gawe{\l}and Kimmel to model the number of repeats of DNA triplets during some genetic disorders. If the process involves some thinning, then extinction and explosion ... More
Harmonic moments of non homogeneous branching processesOct 03 2005We study the harmonic moments of Galton-Watson processes, possibly non homogeneous, with positive values. Good estimates of these are needed to compute unbiased estimators for non canonical branching Markov processes, which occur, for instance, in the ... More
Counting and Equidistribution for Quaternion AlgebrasOct 05 2018Dec 26 2018We aim at studying automorphic forms of bounded analytic conductor in the division quaternion algebra setting. We prove the equidistribution of the universal family with respect to an explicit and geometrically meaningful measure. It leads to answering ... More
Semidefinite geometry of the numerical rangeDec 09 2008The numerical range of a matrix is studied geometrically via the cone of positive semidefinite matrices (or semidefinite cone for short). In particular it is shown that the feasible set of a two-dimensional linear matrix inequality (LMI), an affine section ... More
Invariance principle for the coverage rate of genomic physical mappingsOct 03 2005We study some stochastic models of physical mapping of genomic sequences. Our starting point is a global construction of the process of the clones and of the process of the anchors which are used to map the sequence. This yields explicit formulas for ... More
Efficient resolution of the Colebrook equationOct 30 2008A robust, fast and accurate method for solving the Colebrook-like equations is presented. The algorithm is efficient for the whole range of parameters involved in the Colebrook equation. The computations are not more demanding than simplified approximations, ... More
XTRA: The fast X-ray timing detector on XEUSJan 08 2004The Rossi X-ray Timing Explorer (RXTE) has demonstrated that the dynamical variation of the X-ray emission from accreting neutron stars and stellar mass black holes is a powerful probe of their strong gravitational fields. At the same time, the X-ray ... More
Homogenizing metamaterials, three timesNov 08 2012The homogenization of a metamaterial made of a collection of scatterers periodically disposed is studied from three different points of view. Specifically tools for multiple scattering theory, functional analysis, differential geometry and optimization ... More
Soft lags in neutron star kHz Quasi Periodic Oscillations: evidence for reverberation?Mar 04 2013Apr 20 2013High frequency soft reverberation lags have now been detected from stellar mass and super massive black holes. Their interpretation involves reflection of a hard source of photons onto an accretion disk, producing a delayed reflected emission, with a ... More
A quantum way for metamaterialsMar 07 2011Mar 09 2011A new future for metamaterials is suggested, involving the insertion of quantum degrees of freedom, under the guise of quantum dots or cold atoms, in an photonic matrix. It is argued that new emergent, quantum, properties could be obtained.
On the Herman-Kluk Semiclassical ApproximationAug 06 2009For a subquadratic symbol $H$ on $\R^d\times\R^d = T^*(\R^d)$, the quantum propagator of the time dependent Schr\"odinger equation $i\hbar\frac{\partial\psi}{\partial t} = \hat H\psi$ is a Semiclassical Fourier-Integral Operator when $\hat H=H(x,\hbar ... More
Non linear eigenvalue problemsDec 06 2004In this paper we consider generalized eigenvalue problems for a family of operators with a polynomial dependence on a complex parameter. This problem is equivalent to a genuine non self-adjoint operator. We discuss here existence of non trivial eigenstates ... More
ECLAIRs: A microsatellite to observe the prompt optical and X-ray emission of Gamma-Ray BurstsMay 21 2002ECLAIRs is a French microsatellite devoted to the observation of the prompt optical and X-ray emission of GRBs. For about 100 GRBs/yr, independent of their duration, ECLAIRs will provide high time resolution high sensitivity spectral coverage from a few ... More
Poles and zeros of the scattering matrix associated to defect modesMar 08 2000We analyze electromagnetic waves propagation in one-dimensional periodic media with single or periodic defects. The study is made both from the point of view of the modes and of the diffraction problem. We provide an explicit dispersion equation for the ... More
Large deviations and portfolio optimizationFeb 05 1998Jun 08 1998Risk control and optimal diversification constitute a major focus in the finance and insurance industries as well as, more or less consciously, in our everyday life. We present a discussion of the characterization of risks and of the optimization of portfolios ... More
Nonlocal adiabatic theory. II. Nonlinear frequency shift of an electron plasma wave in a multidimensional inhomogeneous plasmaJun 12 2017Sep 15 2017In this article, we provide a general derivation of the nonlinear frequency shift, $\delta \omega$, for a sinusoidal electron plasma wave (EPW) that varies slowly enough for the results derived in the companion paper, on the action distribution function, ... More
Envelope equation for the linear and nonlinear propagation of an electron plasma wave, including the effects of Landau damping, trapping, plasma inhomogeneity, and the change in the state of waveJul 20 2016Sep 13 2016This paper addresses the linear and nonlinear three-dimensional propagation of an electron wave in a collisionless plasma that may be inhomogeneous, nonstationary, anisotropic and even weakly magnetized. The wave amplitude, together with any hydrodynamic ... More
Confidence intervals for nonhomogeneous branching processes and polymerase chain reactionsMar 29 2005We extend in two directions our previous results about the sampling and the empirical measures of immortal branching Markov processes. Direct applications to molecular biology are rigorous estimates of the mutation rates of polymerase chain reactions ... More
Maximal generalization of Baum-Katz theorem and optimality of sequential testsOct 03 2005Baum-Katz theorem asserts that the Cesaro means of i.i.d. increments distributed like X r-converge if and only if |X|^{r+1} is integrable. We generalize this, and we unify other results, by proving that the following equivalence holds, if and only if ... More
Low-lying zeros of L-functions for Quaternion AlgebrasOct 30 2018The density conjecture of Katz and Sarnak predicts that, for natural families of L-functions, the distribution of zeros lying near the real axis is governed by a group of symmetry. In the case of the universal family of automorphic forms of bounded analytic ... More
Some control design experiments with HIFOOSep 01 2006A new MATLAB package called HIFOO was recently proposed for H-infinity fixed-order controller design. This document illustrates how some standard controller design examples can be solved with this software.
Quasiclassical theory of electronic transport in mesoscopic systems: Luttinger liquids revisitedSep 21 2006Dec 13 2006The method of the quasiclassical Green's function is used to determine the equilibrium properties of one-dimensional (1D) interacting Fermi systems, in particular, the bulk and the local (near a hard wall) density of states. While this is a novel approach ... More
Andreev tunnelling in quantum dots: A slave-boson approachJun 05 1998We study a strongly interacting quantum dot connected to a normal and to a superconducting lead. By means of the slave-boson technique we investigate the low temperature regime and discuss electrical transport through the dot. We find that the zero bias ... More
Tuning the Spin Hall Effect in a Two-Dimensional Electron GasMay 08 2009We provide a theoretical framework for the electric field control of the electron spin in systems with diffusive electron motion. The approach is valid in the experimentally important case where both intrinsic and extrinsic spin-orbit interaction in a ... More
Magnetoconductance of a two-dimensional metal in the presence of spin-orbit couplingOct 22 2001We show that in the metallic phase of a two dimensional electron gas the spin-orbit coupling due to structure inversion asymmetry leads to a characteristic anisotropy in the magnetoconductance. Within the assumption that the metallic phase can be described ... More
Andreev Tunneling in Strongly Interacting Quantum DotsDec 17 1998Apr 20 1999We review recent work on resonant Andreev tunneling through a strongly interacting quantum dot connected to a normal and to a superconducting lead. We derive a general expression for the current flowing in the structure and discuss the linear and non-linear ... More
Spin-Hall effect in a disordered 2D electron-systemAug 11 2004We calculate the spin-Hall conductivity for a two-dimensional electron gas within the self-consistent Born approximation, varying the strength and type of disorder. In the weak disorder limit we find both analytically and numerically a vanishing spin-Hall ... More
On Cayley graphs of basic algebraic structuresMar 15 2019We present simple graph-theoretic characterizations of Cayley graphs for monoids, semigroups and groups. We extend these characterizations to commutative monoids, semilattices, and abelian groups.
Harmonic continuous-time branching momentsNov 02 2005Feb 14 2007We show that the mean inverse populations of nondecreasing, square integrable, continuous-time branching processes decrease to zero like the inverse of their mean population if and only if the initial population $k$ is greater than a first threshold $m_1\ge1$. ... More
Time Evolution of States for Open Quantum Systems. The quadratic caseAug 08 2012Nov 16 2012Our main goal in this paper is to extend to any system of coupled quadratic Hamiltonians some properties known for systems of quantum harmonic oscillators related with the Brownian Quantum Motion model. In a first part we get a rather general formula ... More
Coherent transport in disordered metals: zero dimensional limitSep 02 2002We consider non-equilibrium transport in disordered conductors. We calculate the interaction correction to the current for a short wire connected to electron reservoirs by resistive interfaces. In the absence of charging effects we find a universal current-voltage-characteristics. ... More
Persistent Currents versus Phase Breaking in Mesoscopic Metallic SamplesJan 21 2002Persistent currents in mesoscopic normal metal rings represent, even a decade after their first experimental observation, a challenge to both, theorists and experimentalists. After giving a brief review of the existing -- experimental and theoretical ... More
Aleksandrov-Bakelman-Pucci Type Estimates For Integro-Differential EquationsDec 31 2010Apr 04 2012In this work we provide an Aleksandrov-Bakelman-Pucci type estimate for a certain class of fully nonlinear elliptic integro-differential equations, the proof of which relies on an appropriate generalization of the convex envelope to a nonlocal, fractional-order ... More
Granger-causal Attentive Mixtures of ExpertsFeb 06 2018Several methods have recently been proposed to detect salient input features for outputs of neural networks. Those methods offer a qualitative glimpse at feature importance, but they fall short of providing quantifiable attributions that can be compared ... More
Compressive Space-Time Galerkin Discretizations of Parabolic Partial Differential EquationsJan 19 2015We study linear parabolic initial-value problems in a space-time variational formulation based on fractional calculus. This formulation uses "time derivatives of order one half" on the bi-infinite time axis. We show that for linear, parabolic initial-boundary ... More
Interplay of intrinsic and extrinsic mechanisms to the spin Hall effect in a two-dimensional electron gasSep 10 2009In order to describe correctly the interplay of extrinsic and intrinsic spin-orbit mechanisms to the spin Hall effect, it is necessary to consider different sources of spin relaxation. We take into account the spin relaxation time $\tau_{DP}$ due to the ... More
Persistent current induced by magnetic impuritiesFeb 05 1997We calculate the average persistent current in a normal conducting, mesoscopic ring in the diffusive regime. In the presence of magnetic impurities, a contribution to the persistent current is identified, which is related to fluctuations in the electron ... More
Optimization of brain and life performance: Striving for playing at the top for the long runNov 20 2011In this essay written with my students and collaborators in mind, I share simple recipes that are easy and often fun to put in practice and that make a big difference in one's life. The seven guiding principles are: (1) sleep, (2) love and sex, (3) deep ... More
Semidefinite representation of convex hulls of rational varietiesJan 13 2009Jan 28 2011Using elementary duality properties of positive semidefinite moment matrices and polynomial sum-of-squares decompositions, we prove that the convex hull of rationally parameterized algebraic varieties is semidefinite representable (that is, it can be ... More
On semidefinite representations of plane quarticsSep 10 2008Sep 22 2008This note focuses on the problem of representing convex sets as projections of the cone of positive semidefinite matrices, in the particular case of sets generated by bivariate polynomials of degree four. Conditions are given for the convex hull of a ... More
Le logo du CNRS est-il convexe ?Oct 17 2008In october 2008, CNRS adopts a new logo with a round shape. We study the mathematical representation of this shape, and in particular its convexity.
Exact diagonalisation studies of strongly correlated 2D lattice fermionsSep 14 1994The T=0 phase diagram of the planar t--J model with small doping is investigated by exact diagonalisations of square clusters with up to 32 sites. At half-filling, the single hole quasi-particule weight vanishes in the strong correlation limit $J\rightarrow ... More
On the Internal Structure of the Singlet d$_{X^2-Y^2}$ Hole Pair in an AntiferromagnetJun 10 1993Exact diagonalizations of two dimensional small t--J clusters reveal dominant hole-hole correlations at distance $\sqrt{2}$ (ie between holes on next nearest neighbor sites). A new form of singlet $d_{x^2-y^2}$ pair operator is proposed to account for ... More
Binding of holes and pair spectral function in the t-J modelMar 17 1993Clusters of the two-dimensionnal t--J model with 2 holes and up to 26 sites are diagonalized using a Lanczos algorithm. The behaviour of the binding energy with system size suggests the existence of a finite critical value of J above which binding occurs ... More
Exotic Mott phases of the extended t--J model on the checkerboard lattice at commensurate densitiesMay 29 2007Coulomb repulsion between electrons moving on a frustrated lattice can give rise, at simple commensurate electronic densities, to exotic insulating phases of matter. Such a phenomenon is illustrated using an extended t--J model on a planar pyrochlore ... More
On two duality properties of random walks in random environment on the integer lineOct 03 2005According to Comets, Gantert and Zeitouni on the one hand and to Derriennic on the other hand, some functionals associated to the hitting times of random walks in random environment on the integer line coincide, for the walk itself and for the walk in ... More
Accretion flows around stellar mass black holes and neutron starsJan 08 2004In this review, I summarize the main X-ray/hard X-ray properties of the accretion flows around black holes and neutron stars based on recent broad-band spectral and timing observations performed by the BeppoSAX and Rossi X-ray Timing Explorer satellites. ... More
Anomalous Quantum Diffusion and Conductivity of QuasicrystalsDec 07 1999A phenomenological diffusion law $L(t)\propto t^{\beta}$, where L(t) measures the spreading of a wave-packet in a time t, is assumed for perfect quasicrystals. We show that it affects their conductivity with striking differences compared to the case of ... More
On Cayley graphs of algebraic structuresMar 22 2018We present simple graph-theoretic characterizations of Cayley graphs for left-cancellative monoids, groups, left-quasigroups and quasigroups. We show that these characterizations are effective for the end-regular graphs of finite degree.
On the Cauchy problem for higher-order nonlinear dispersive equationsAug 27 2007We study a class of higher-order KdV equations. We show that the associated initial value problem is well posed in weighted Besov and Sobolev spaces for small initial data. We also prove ill-posedness results when in H^s(\R), for any real s.
On convexity of the frequency response of a stable polynomialSep 07 2007In the complex plane, the frequency response of a univariate polynomial is the set of values taken by the polynomial when evaluated along the imaginary axis. This is an algebraic curve partitioning the plane into several connected components. In this ... More
Comment on "Why does deep and cheap learning work so well?" [arXiv:1608.08225]Sep 12 2016In a recent paper, "Why does deep and cheap learning work so well?", Lin and Tegmark claim to show that the mapping between deep belief networks and the variational renormalization group derived in [arXiv:1410.3831] is invalid, and present a "counterexample" ... More
Neumann Homogenization via Integro-Differential Operators, Part 2: singular gradient dependenceDec 18 2015We continue the program initiated in a previous work, of applying integro-differential methods to Neumann Homogenization problems. We target the case of linear periodic equations with a singular drift, which includes (with some regularity assumptions) ... More
Min-max formulas for nonlocal elliptic operatorsJun 27 2016Oct 25 2016In this work, we give a characterization of Lipschitz operators on spaces of $C^2(M)$ functions (also $C^{1,1}$, $C^{1,\gamma}$, $C^1$, $C^\gamma$) that obey the global comparison property-- i.e. those that preserve the global ordering of input functions ... More
Quantum Measurement of a Coupled Nanomechanical Resonator -- Cooper-Pair Box SystemJan 15 2003Jul 31 2003We show two effects as a result of considering the second-order correction to the spectrum of a nanomechanical resonator electrostatically coupled to a Cooper-pair box. The spectrum of the Cooper-pair box is modified in a way which depends on the Fock ... More
The deterministic information bottleneckApr 01 2016Compression fundamentally involves a decision about what is relevant and what is not. The information bottleneck method (IB) by Tishby, Pereira, and Bialek formalized this notion as an information-theoretic optimization problem and proposed an optimal ... More
Wait for it: Post-supernova winds driven by delayed radioactive decaysOct 20 2016In most astrophysical situations, the radioactive decay of 56Ni to 56Co occurs via electron capture with a fixed half-life of 6.1 days. However, this decay rate is significantly slowed when the nuclei are fully ionized because K-shell electrons are unavailable ... More
Min-max formulas for nonlocal elliptic operatorsJun 27 2016In this work, we give a characterization of Lipschitz operators on spaces of $C^2(M)$ functions (also $C^{1,1}$, $C^{1,\gamma}$, $C^1$, $C^\gamma$) that obey the global comparison property-- i.e. those that preserve the global ordering of input functions ... More
Sparse Deterministic Approximation of Bayesian Inverse ProblemsMar 23 2011Feb 08 2012We present a parametric deterministic formulation of Bayesian inverse problems with input parameter from infinite dimensional, separable Banach spaces. In this formulation, the forward problems are parametric, deterministic elliptic partial differential ... More
Glassy states in fermionic systems with strong disorder and interactionsAug 11 2008Feb 03 2009We study the competition between interactions and disorder in two dimensions. Whereas a noninteracting system is always Anderson localized by disorder in two dimensions, a pure system can develop a Mott gap for sufficiently strong interactions. Within ... More
The Weak Efficient Market Hypothesis in Light of Statistical LearningOct 12 2016We make an unprecedented evaluation of statistical learning methods to forecast daily returns. Using a randomization test to adjust for data snooping, several models are found statistically significant on the tested equity indices: CSI 300, FTSE, and ... More
Finding largest small polygons with GloptiPolyMar 23 2011A small polygon is a convex polygon of unit diameter. We are interested in small polygons which have the largest area for a given number of vertices $n$. Many instances are already solved in the literature, namely for all odd $n$, and for $n=4, 6$ and ... More
On Variational Micro-Macro Models and their Application to PolycrystalsNov 24 2006Some variational micro-macro models are briefly reviewed: it is shown how, starting from the Taylor model and passing through the relaxed Taylor model, a consistent intermediate between Taylor's upper bound and the lower bound (Sachs or rather "static") ... More
The Cauchy problem for the Benjamin-Ono equation in $L^2$ revisitedJul 09 2010In a recent work, Ionescu and Kenig proved that the Cauchy problem associatedto the Benjamin-Ono equation is well-posed in $L^2(\mathbb R)$. In this paper we give a simpler proof of Ionescu and Kenig's result, which moreover provides stronger uniqueness ... More
Astrocladistics: Multivariate Evolutionary Analysis in AstrophysicsMay 31 2010The Hubble tuning fork diagram, based on morphology and established in the 1930s, has always been the preferred scheme for classification of galaxies. However, the current large amount of data up to higher and higher redshifts asks for more sophisticated ... More
A centerless representation of the Virasoro algebra associated with the unitary circular ensembleJan 24 2010We consider the 2-dimensional Toda lattice tau functions $\tau_n(t,s;\eta,\theta)$ deforming the probabilities $\tau_n(\eta,\theta)$ that a randomly chosen matrix from the unitary group U(n), for the Haar measure, has no eigenvalues within an arc $(\eta,\theta)$ ... More
Hermite matrix in Lagrange basis for scaling static output feedback polynomial matrix inequalitiesJan 20 2010Using Hermite's formulation of polynomial stability conditions, static output feedback (SOF) controller design can be formulated as a polynomial matrix inequality (PMI), a (generally nonconvex) nonlinear semidefinite programming problem that can be solved ... More
The achromatic chessboard, a new concept of phase shifter for Nulling Interferometry - I. theoryFeb 22 2008Direct detection of a planet around a star in the mid-IR, requires a nulling interferometer featuring an achromatic phase shift of pi on broad range. A new concept for designing such an achromatic phase shifter is presented here. The major interest of ... More
Superconducting fluctuations in the Luther-Emery liquidMar 04 2003The single-particle superconducting Green's functions of a Luther-Emery liquid is computed by bosonization techniques. Using a formulation introduced by Poilblanc and Scalapino [Phys. Rev. B v. 66, art. 052513 (2002)], an asymptotic expression of the ... More
Charge density correlations in t-J ladders investigated by the CORE methodAug 16 2002Oct 11 2002Using 4-site plaquette or rung basis decomposition, the CORE method is applied to 2-leg and 4-leg t-J ladders and cylinders. Resulting range-2 effective hamiltonians are studied numerically on periodic rings taking full advantage of the translation symmetry ... More
Quis pendit ipsa pretia: facebook valuation and diagnostic of a bubble based on nonlinear demographic dynamicsOct 06 2011Nov 01 2011We present a novel methodology to determine the fundamental value of firms in the social-networking sector based on two ingredients: (i) revenues and profits are inherently linked to its user basis through a direct channel that has no equivalent in other ... More
Multivariate Evolutionary Analyses in AstrophysicsJun 19 2011The large amount of data on galaxies, up to higher and higher redshifts, asks for sophisticated statistical approaches to build adequate classifications. Multivariate cluster analyses, that compare objects for their global similarities, are still confidential ... More
Strong gender differences in reproductive success variance, and the times to the most recent common ancestorsMar 28 2012The Time To the Most Recent Common Ancestor (TMRCA) based on human mitochondrial DNA (mtDNA) is estimated to be twice that based on the non-recombining part of the Y chromosome (NRY). These TMRCAs have special demographic implications because mtDNA is ... More
Positive trigonometric polynomials for strong stability of difference equationsNov 05 2010We follow a polynomial approach to analyse strong stability of linear difference equations with rationally independent delays. Upon application of the Hermite stability criterion on the discrete-time homogeneous characteristic polynomial, assessing strong ... More
Designing optimal- and fast-on-average pattern matching algorithmsApr 28 2016Aug 29 2016Given a pattern $w$ and a text $t$, the speed of a pattern matching algorithm over $t$ with regard to $w$, is the ratio of the length of $t$ to the number of text accesses performed to search $w$ into $t$. We first propose a general method for computing ... More
Magnetic ordering in doped coupled frustrated quantum spin-1/2 chains with 4-spin exchangeJan 22 2004Jun 09 2004The role of various magnetic inter-chain couplings has been investigated recently by numerical methods in doped frustrated quantum spin chains. A non-magnetic dopant introduced in a gapped spin chain releases a free spin-1/2 soliton. The formation of ... More
Classification of Possible Finite-Time Singularities by Functional RenormalizationNov 09 2001Starting from a representation of the early time evolution of a dynamical system in terms of the polynomial expression of some observable f (t) as a function of the time variable in some interval 0 < t < T, we investigate how to extrapolate/forecast in ... More
Parity violation and the mean field approximation for the anyon gasMar 14 1993We examine an approach to justifying the mean field approximation for the anyon gas, using the scattering of anyons. Parity violation permits a nonzero average scattering angle, from which one can extract a mean radius of curvature for anyons. If this ... More