Results for "Matthieu Bethermin"

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Towards a new modelling of gas flows in a semi-analytical model of galaxy formation and evolutionOct 18 2014Feb 02 2015We present an extended version of the semi-analytical model, GalICS. Like its predecessor, eGalICS applies a post-treatment of the baryonic physics on pre-computed dark-matter merger trees extracted from an N-body simulation. We review all the mechanisms ... More
Galaxy stellar mass assembly: the difficulty matching observations and semi-analytical predictionsOct 18 2014Feb 02 2015Semi-analytical models (SAMs) are currently the best way to understand the formation of galaxies within the cosmic dark-matter structures. While they fairly well reproduce the local stellar mass functions, correlation functions and luminosity functions, ... More
Panchromatic Study of the First Galaxies with Large ALMA ProgramsJan 04 2019Thanks to deep optical to near-IR imaging and spectroscopy, significant progress is made in characterizing the rest-frame UV to optical properties of galaxies in the early universe (z > 4). Surveys with Hubble, Spitzer, and ground-based facilities (Keck, ... More
Taking Census of Massive, Star-Forming Galaxies formed <1 Gyr After the Big BangMar 13 2019Two decades of effort have been poured into both single-dish and interferometric millimeter-wave surveys of the sky to infer the volume density of dusty star-forming galaxies (DSFGs, with SFR>100M$_\odot$ yr$^{-1}$) over cosmic time. Though obscured galaxies ... More
Fujita blow up phenomena and hair trigger effect: the role of dispersal tailsMay 03 2016We consider the nonlocal diffusion equation $\partial \_t u=J*u-u+u^{1+p}$ in the whole of $\R ^N$. We prove that the Fujita exponent dramatically depends on the behavior of the Fourier transform of the kernel $J$ near the origin, which is linked to the ... More
Efficient and Playful Tools to Teach Unix to New StudentsMar 09 2011Teaching Unix to new students is a common tasks in many higher schools. This paper presents an approach to such course where the students progress autonomously with the help of the teacher. The traditional textbook is complemented with a wiki, and the ... More
Approximability of dynamical systems between trees of spheresAug 09 2014We study sequences of analytic conjugacy classes of rational maps which diverge in moduli space. In particular, we are interested in the notion of rescaling limits introduced by Jan Kiwi. In the continuity of [A1] we recall the notion of dynamical covers ... More
A Chevalley formula in equivariant $K$-theoryMar 09 2006The aim of this paper is to give a recursive formula to multiply a line bundle with the structure sheaf of a schubert variety in the equivariant $K$-theory of a flag variety.
Paysage Systolique Des Surfaces Hyperboliques Compactes De Caracteristique -1Aug 01 2005We determine optimal inequalities for the systole of all hyperbolic compact surfaces of caracteristic -1. First, we study the geometry and topology of these surfaces. Then, we describe the action of modular groups on Teichm\"{u}ller spaces. Finaly, we ... More
Gold Standard for Expert Ranking: A Survey on the XWiki DatasetMar 11 2016We are designing an automated technique to find and recommend experts for helping in Requirements Engineering tasks, which can be done by ranking the available people by level of expertise. For evaluating the correctness of the rankings produced by the ... More
K-theorie equivariante des varietes de Bott-Samelson. Application a la structure multiplicative de la K-theorie equivariante des varietes de drapeauxDec 07 2004We construct a basis of the equivariant $K$-theory of Bott towers, and we describe precisely the multiplicative structure of these algebras. We deduce similar results for Bott-Samelson varieties. Thanks to the link between flag varieties and Bott-Samelson ... More
Linking rigidity transitions with enthalpic changes at the glass transition and the fragility of glass-forming liquidsMar 13 2008A low temperature Monte Carlo dynamics of a Keating like oscillator model is used to study the relationship between the nature of glasses from the viewpoint of rigidity, and the strong-fragile behaviour of glass-forming liquids. The model shows that a ... More
Intermediate phase in molecular networks and solid electrolytesJun 24 2002There is growing evidence that electronic and molecular networks present some common universal properties, among which the existence of a self-organized intermediate phase. In glasses, the latter is revealed by the reversibility window obtained from complex ... More
Dual Garside structure and reducibility of braidsMay 18 2011Feb 22 2012Benardete, Gutierrez and Nitecki showed an important result which relates the geometrical properties of a braid, as a homeomorphism of the punctured disk, to its algebraic Garside-theoretical properties. Namely, they showed that if a braid sends a curve ... More
Exact solution to integrable open multi-species SSEP and macroscopic fluctuation theoryOct 26 2016We introduce a multi-species generalization of the symmetric simple exclusion process with open boundaries. This model possesses the property of being integrable and appears as physically relevant because the boundary conditions can be interpreted as ... More
Latest results on Galactic sources as seen in VHE gamma-raysMay 08 2009As of early 2009, latest results on Galactic sources (mainly shell-type and plerionic supernova remnants), as observed in the very-high-energy gamma-ray domain, are reviewed. A particular attention is given to those obtained with the H.E.S.S experiment ... More
A note on group actions on algebraic stacksMay 16 2003We give the basic definitions of group actions on (algebraic) stacks, and prove the existence of fixed points and quotients as (algebraic) stacks.
Effective model of a finite group actionJan 26 2006Let $R$ be a discrete valuation ring with fraction field $K$. Let $X$ be a flat $R$-scheme of finite type and $G$ a finite flat group scheme acting on $X$ so that $G\_K$ is faithful on the generic fibre $X\_K$. We prove that there is an effective model ... More
Rigidity and intermediate phases in glasses driven by speciationMar 31 2006The rigid to floppy transitions and the associated intermediate phase in glasses are studied in the case where the local structure is not fully determined from the macroscopic concentration. The approach uses size increasing cluster approximations and ... More
Solvable models of Glass TransitionSep 02 1999Simple statistical agglomeration models can provide a universal link between the local structure and the glass transition temperature in network glasses. We first stress the physical features of the models and the hypothesis made, and then show how to ... More
How to compute Selberg-like integrals?Jul 13 2010In this paper, we describe a general method for computing Selberg-like integrals based on a formula, due to Kaneko, for Selberg-Jack integrals. The general principle consists in expanding the integrand \emph{w.r.t.} the Jack basis, which is obtained by ... More
Elasticity of soft particles and colloids near Random Close PackingJun 28 2008Jul 14 2009Assemblies of purely repulsive and frictionless particles, such as emulsions or hard spheres, display very curious properties near their jamming transition, which occurs at the random close packing for mono-disperse spheres. Although such systems do not ... More
Dynamics of post-critically finite maps in higher dimensionSep 09 2016We study the dynamics of post-critically finite endomorphisms of P^k(C). We prove that post-critically finite endomorphisms are always post-critically finite all the way down under a mild regularity condition on the post-critical set. We study the eigenvalues ... More
On the homogenization of the Stokes problem in a perforated domainApr 15 2016Sep 06 2016We consider the Stokes equations on a bounded perforated domaincompleted with non-zero constant boundary conditions on the holes. We investigate configurations forwhich the holes are identical spheres and their number N goes to infinity while their radius1/N ... More
Mitigation Procedures to Rank Experts through Information Retrieval MeasuresMar 16 2016In order to find experts, different approaches build rankings of people, assuming that they are ranked by level of expertise, and use typical Information Retrieval (IR) measures to evaluate their effectiveness. However, we figured out that expert rankings ... More
Summability Condition and Rigidity for Finite Type MapsFeb 16 2016We extend a series of results due to Makienko, Dominguez and Sienra on the rigidity of some holomorphic dynamical systems with summable critical values to the setting of finite type maps. We also recover a shorter proof of a transversality theorem of ... More
The injectivity radius of hyperbolic surfaces and some Morse functions over moduli spacesOct 09 2015This article is devoted to the variational study of two functions defined over some Teichmueller spaces of hyperbolic surfaces. One is the systole of geodesic loops based at some fixed point, and the other one is the systole of arcs.\par For each of them ... More
On the dynamical Teichmüller spaceJun 05 2014Jul 01 2014We prove that the dynamical Teichm\"uller space of a rational map immerses into the space of rational maps of the same degree, answering a question of McMullen and Sullivan. This is achieved through a new description of the tangent and cotangent space ... More
Trois applications du lemme de Schwarz aux surfaces hyperboliquesApr 17 2014Through the Schwarz lemma, we provide a new point of view on three well-known results of the geometry of hyperbolic surfaces. The first result deal with the length of closed geodesics on hyperbolic surfaces with boundary (Thurston, Parlier, Papadopoulos-Th\'eret). ... More
Estimating Subagging by cross-validationNov 23 2010In this article, we derive concentration inequalities for the cross-validation estimate of the generalization error for subagged estimators, both for classification and regressor. General loss functions and class of predictors with both finite and infinite ... More
Compactification and trees of spheres coversAug 09 2014We already saw in [A1] that the space of dynamically marked rational maps can be identified to a subspace of the space of covers between trees of spheres on which there is a notion of convergence that makes it sequentially compact. In the following we ... More
Concentration inequalities of the cross-validation estimator for Empirical Risk MinimiserOct 30 2010In this article, we derive concentration inequalities for the cross-validation estimate of the generalization error for empirical risk minimizers. In the general setting, we prove sanity-check bounds in the spirit of \cite{KR99} \textquotedblleft\textit{bounds ... More
Rigidity-based approach to the boson peak in amorphous solids: from sphere packing to amorphous silicaJun 27 2008Glasses have a large excess of low-frequency vibrational modes in comparison with continuous elastic body, the so-called Boson Peak, which appears to correlate with several crucial properties of glasses, such as transport or fragility. I review recent ... More
The Singular Limit of a Chemotaxis-Growth System with General Initial DataSep 16 2009We study the singular limit of a system of partial differential equations which is a model for an aggregation of amoebae subjected to three effects: diffusion, growth and chemotaxis. The limit problem involves motion by mean curvature together with a ... More
Automatic structures for torus link groupsNov 07 2001A general result of Epstein and Thurston implies that all link groups are automatic, but the proof provides no explicit automaton. Here we show that the groups of all torus links are groups of fractions of so-called Garside monoids, i.e., roughly speaking, ... More
Cohomologie equivariante des varietes de Bott-SamelsonJan 08 2002In this text, We compute the equivariant cohomology of Bott-Samelson varieties. Thanks to this computation, we give a new demonstration for the formulas proved by Sarah Billey for the equivariant cohomology of Schubert varieties.
How far away must forced letters be so that squares are still avoidable?Mar 11 2019We describe a new non-constructive technique to show that squares are avoidable by an infinite word even if we force some letters from the alphabet to appear at certain occurrences. We show that as long as forced positions are at distance at least 3 (resp. ... More
Derivatives of length functions and shearing coordinates on teichm{ü}ller spacesJun 22 2015Jun 23 2015Let $S$ be a closed oriented surface of genus at least $2$, and denote by $\mathcal{T}(S)$ its Teichm{\"u}ller space. For any isotopy class of closed curves $\gamma$, we compute the first three derivatives of the length function $\ell\_\gamma:\mathcal{T}(S)\rightarrow\mathbf{R}\_+$ ... More
Dynamics on Trees of SpheresJun 24 2014We introduce the notion of dynamically marked rational maps. We study sequences of analytic conjugacy classes of rational maps which diverge in moduli space. In particular, we are interested in the notion of rescaling limits introduced by Jan Kiwi. In ... More
Comparison bewteen multi-task and single-task oracle risks in kernel ridge regressionJul 19 2013In this paper we study multi-task kernel ridge regression and try to understand when the multi-task procedure performs better than the single-task one, in terms of averaged quadratic risk. In order to do so, we compare the risks of the estimators with ... More
Fast nielsen-thurston classification of braidsDec 01 2011Oct 24 2013We prove the existence of an algorithm which solves the reducibility problem in braid groups and runs in quadratic time with respect to the braid length for any fixed braid index.
K-theorie equivariante des varietes de drapeaux et des varietes de Bott-SamelsonApr 22 2002The aim of this text is to give an explicit formula for the restriction to fixed points of a basis of the equivariant K-theory of the flag varieties and of the Bott-Samelson varieties.
Second order phase transitions induced by disorder in frustrated magnetsMar 19 2002Apr 04 2002We study the critical properties of three dimensional frustrated magnets, diluted with non-magnetic impurities. We show that these systems exhibit a second order phase transition, corresponding to a new universality class. In the pure case, the phase ... More
Automatic semigroups vs automaton semigroupsSep 29 2016We develop an effective and natural approach to interpret any semigroup admitting a special language of greedy normal forms as an automaton semigroup, namely the semigroup generated by a Mealy automaton encoding the behaviour of such a language of greedy ... More
Simulation of a Local Time Fractional Stable MotionDec 19 2007Jul 16 2008In this paper, we simulate sample paths of a class of symmetric $\alpha$-stable processes using their series expression. We will develop a result in the approximation of shot-noise series. And finally, we will get a convergence rate for the approximation. ... More
Optimal model selection in density estimationOct 09 2009Jul 26 2010We build penalized least-squares estimators using the slope heuristic and resampling penalties. We prove oracle inequalities for the selected estimator with leading constant asymptotically equal to 1. We compare the practical performances of these methods ... More
On paths-based criteria for polynomial time complexity in proof-netsJan 13 2012May 19 2014Girard's Light linear logic (LLL) characterized polynomial time in the proof-as-program paradigm with a bound on cut elimination. This logic relied on a stratification principle and a "one-door" principle which were generalized later respectively in the ... More
Le lemme de Schwarz et la borne supérieure du rayon d'injectivité des surfacesApr 17 2014We study the injectivity radius of complete Riemannian surfaces (S,g) with curvature |K(g)| bounded by 1. We show that if S is orientable with nonabelian fundamental group, then there is a point p in S with injectivity radius at least arcsinh(2/\sqrt{3}). ... More
Correlations between vibrational entropy and dynamics in super-cooled liquidsNov 20 2009Jun 20 2010A relation between vibrational entropy and particles mean square displacement is derived in super-cooled liquids, assuming that the main effect of temperature changes is to rescale the vibrational spectrum. Deviations from this relation, in particular ... More
Scaling of phononic transport with connectivity in amorphous solidsSep 16 2009Mar 01 2010The effect of coordination on transport is investigated theoretically using random networks of springs as model systems. An effective medium approximation is made to compute the density of states of the vibrational modes, their energy diffusivity (a spectral ... More
Hardcore dimer aspects of the SU(2) Singlet wavefunctionJun 17 2007Apr 17 2008We demonstrate that any SU(2) singlet wavefunction can be characterized by a set of Valence Bond occupation numbers, testing dimer presence/vacancy on pairs of sites. This genuine quantum property of singlet states (i) shows that SU(2) singlets share ... More
On the Rigidity of Amorphous SolidsDec 07 2005We poorly understand the properties of amorphous systems at small length scales, where a continuous elastic description breaks down. This is apparent when one considers their vibrational and transport properties, or the way forces propagate in these solids. ... More
Cohomologie et $K$-theorie equivariantes des tours de Bott et des varietes de drapeaux. Application au calcul de SchubertNov 06 2003We determine the structure of the equivariant cohomology and $K$-theory of Bott towers. By restriction, we obtain similar results for Bott-Samelson varieties. This results allow us to describe more precisely the equivariant cohomology and $K$-theory of ... More
Combinatorial Semigroup BialgebrasNov 20 2012Jun 04 2013This paper is devoted to the presentation of combinatorial bialgebras whose coproduct is defined with the help of a commutative semigroup. We consider this setting in order to give a general framework which admits as special cases the shuffle and stuffle ... More
Concentration inequalities of the cross-validation estimate for stable predictorsNov 23 2010In this article, we derive concentration inequalities for the cross-validation estimate of the generalization error for stable predictors in the context of risk assessment. The notion of stability has been first introduced by \cite{DEWA79} and extended ... More
Generation, motion and thickness of transition layers for a nonlocal Allen-Cahn equationJun 07 2009We investigate the behavior, as a small parameter tends to zero, of a nonlocal Allen-Cahn equation. Given a rather general initial data, we perform a rigorous analysis of both the generation and the motion of interface, and obtain a new estimate for its ... More
NP-completeness of Certain Sub-classes of the Syndrome Decoding ProblemDec 02 2009The problem of Syndrome Decoding was proven to be NP-complete in 1978 and, since then, quite a few cryptographic applications have had their security rely on the (provable) difficulty of solving some instances of it. However, in most cases, the instances ... More
Garside monoids vs divisibility monoidsJul 05 2007Divisibility monoids (resp. Garside monoids) are a natural algebraic generalization of Mazurkiewicz trace monoids (resp. spherical Artin monoids), namely monoids in which the distributivity of the underlying lattices (resp. the existence of common multiples) ... More
Concentration inequalities for $s$-concave measures of dilations of Borel sets and applicationsJul 01 2008We prove a sharp inequality conjectured by Bobkov on the measure of dilations of Borel sets in $\mathbb{R}^n$ by a $s$-concave probability. Our result gives a common generalization of an inequality of Nazarov, Sodin and Volberg and a concentration inequality ... More
Explicit Presentations for the Dual Braid MonoidsNov 27 2001Birman, Ko and Lee have introduced a new monoid ${\cal B}^{*}_{n}$--with an explicit presentation--whose group of fractions is the $n$-strand braid group ${\cal B}_{n}$. Building on a new approach by Digne, Michel and himself, Bessis has defined a {\it ... More
Tree products of cyclic groups and HNN extensionsJun 24 2013Jul 13 2015Garside groups are a natural lattice-theoretic generalization of the braid groups and spherical type Artin-Tits groups. Here we show that the class of Garside groups is closed under some free product with cyclic amalgamated subgroups. We deduce that every ... More
Finite transducers for divisibility monoidsJan 13 2006Divisibility monoids are a natural lattice-theoretical generalization of Mazurkiewicz trace monoids, namely monoids in which the distributivity of the involved divisibility lattices is kept as an hypothesis, but the relations between the generators are ... More
Caractérisations des espaces projectifs et des quadriquesSep 07 2010Sep 10 2010In this paper we prove the following result : if the p-th tensor power of the tangent bundle of a smooth projective variety contains the p-th power of an ample line bundle, then the variety is isomorphic either to the projective space or to a smooth quadric ... More
The slope equations: a universal relationship between local structure and glass transition temperatureMay 12 1998In this article, we present a universal relationship between the glass transition temperature $T_g$ and the local glass structure. The derivation of the simplest expression of this relationship and some comparisons with experimental $T_g$ values have ... More
Structure of densified germanium dioxideOct 28 2003Classical molecular dynamics simulations are used to study the structure of densified germanium dioxide ($GeO_2$). It is found that the coordination number of germanium changes with increasing density (pressure) while pressure released systems do not ... More
Nucleation model for the description of glass formationSep 16 1998We present in this letter a model of glass formation using energy barriers and a crystal nucleation process. We then analyze the corresponding dynamical equation in the vicinity of the stationary solutions. The occurence of a pure amorphous solution (i.e. ... More
Adaptive non-asymptotic confidence balls in density estimationJul 26 2010We build confidence balls for the common density $s$ of a real valued sample $X_1,...,X_n$. We use resampling methods to estimate the projection of $s$ onto finite dimensional linear spaces and a model selection procedure to choose an optimal approximation ... More
Optimal model selection for density estimation of stationary data under various mixing conditionsNov 08 2009Dec 13 2011We propose a block-resampling penalization method for marginal density estimation with nonnecessary independent observations. When the data are $\beta$ or $\tau$-mixing, the selected estimator satisfies oracle inequalities with leading constant asymptotically ... More
Slowing Allee effect vs. accelerating heavy tails in monostable reaction diffusion equationsMay 18 2015We focus on the spreading properties of solutions of monostable reaction-diffusion equations. Initial data are assumed to have heavy tails, which tends to accelerate the invasion phenomenon. On the other hand, the nonlinearity involves a weak Allee effect, ... More
Berkovich spaces and Deligne-Mumford compactificationJun 08 2015We explicit the relation between the dynamics the Berkovich projective line over the completion of the field of formal Puiseux series and the space dynamical systems between trees of spheres known to be equivalent to the Deligne-Mumford compactification ... More
Search for extra-dimensions, top-antitop resonances, 4th generation and leptoquark signatures at the LHCMay 14 2013The searches for extra-dimensions, top resonances, 4th generation quarks and leptoquark signatures are presented. The results are based on proton-proton collision data for a center-of mass energy of7 or 8 TeV, corresponding to various integrated luminosities. ... More
Stability at Random Close PackingFeb 01 2012Apr 13 2012The requirement that packings of hard particles, arguably the simplest structural glass, cannot be compressed by rearranging their network of contacts is shown to yield a new constraint on their microscopic structure. This constraint takes the form a ... More
Systole et rayon maximal des variétés hyperboliques non compactesJul 28 2011We bound two global invariants of cusped hyperbolic manifolds: the length of the shortest closed geodesic (the systole), and the radius of the biggest embedded ball (the inradius). We give an upper bound for the systole, expressed in terms of the dimension ... More
On the dependence of the avalanche angle on the granular layer thicknessJul 31 2008A layer of sand of thickness h flows down a rough surface if the inclination is larger than some threshold value theta which decreases with h. A tentative microscopic model for the dependence of theta with h is proposed for rigid frictional grains, based ... More
Theory and Practice of Triangle Problems in Very Large (Sparse (Power-Law)) GraphsSep 20 2006Finding, counting and/or listing triangles (three vertices with three edges) in large graphs are natural fundamental problems, which received recently much attention because of their importance in complex network analysis. We provide here a detailed state ... More
Adaptive density estimation for stationary processesSep 05 2009We propose an algorithm to estimate the common density $s$ of a stationary process $X_1,...,X_n$. We suppose that the process is either $\beta$ or $\tau$-mixing. We provide a model selection procedure based on a generalization of Mallows' $C_p$ and we ... More
Determinants of finite-dimensional algebrasDec 12 2007Dec 13 2007To each associative unitary finite-dimensional algebra over a normal base, we associative a canonical multiplicative function called its determinant. We give various properties of this construction, as well as applications to the topology of the moduli ... More
Reading escaping trees from Hubbard trees in SnMar 09 2015We prove that the parameter space of monic centered cubic polynomials with a critical point of exact period n=4 is connected. The techniques developed for this proof work for every n and provide an interesting relation between escaping trees of DeMarco-McMullen ... More
The stack of Potts curves and its fibre at a prime of wild ramificationJan 30 2002May 18 2003In this article we study the modular properties of a family of cyclic coverings of P^1 of degree N, in all odd characteristics. We compute the moduli space of the corresponding algebraic stack over Z[1/2], as well as the Picard groups over algebraically ... More
Effective models of group schemesApr 21 2009Oct 07 2009Let $R$ be a discrete valuation ring with fraction field $K$ and $X$ a flat $R$-scheme. Given a faithful action of a $K$-group scheme $G_K$ over the generic fibre $X_K$, we study models $G$ of $G_K$ acting on $X$. In various situations, we prove that ... More
Composantes connexes et irréductibles en famillesDec 14 2009Feb 18 2010For an algebraic stack $\sX$ flat and of finite presentation over a scheme $S$, we introduce various notions of {\em relative connected components} and {\em relative irreducible components}. The main distinction between these notions is whether we require ... More
The far infra-red SEDs of main sequence and starburst galaxiesJul 19 2016We compare observed far infra-red/sub-millimetre (FIR/sub-mm) galaxy spectral energy distributions (SEDs) of massive galaxies ($M_{\star}\gtrsim10^{10}$ $h^{-1}$M$_{\odot}$) derived through a stacking analysis with predictions from a new model of galaxy ... More
Acylindrical hyperbolicity and Artin-Tits groups of spherical typeJun 24 2016We prove that, for any irreducible Artin-Tits group of spherical type $G$, the quotient of $G$ by its center is acylindrically hyperbolic. This is achieved by studying the additional length graph associated to the classical Garside structure on $G$, and ... More
Interface dynamics of the porous medium equation with a bistable reaction termJul 18 2011We consider a degenerate partial differential equation arising in population dynamics, namely the porous medium equation with a bistable reaction term. We study its asymptotic behavior as a small parameter, related to the thickness of a diffuse interface, ... More
Propagating interface in a monostable reaction-diffusion equation with time delaySep 25 2012We consider a monostable time-delayed reaction-diffusion equation arising from population dynamics models. We let a small parameter tend to zero and investigate the behavior of the solutions. We construct accurate lower barriers --- by using a non standard ... More
Rapid travelling waves in the nonlocal Fisher equation connect two unstable statesMay 10 2012In this note, we give a positive answer to a question addressed in \cite{Nad-Per-Tan}. Precisely we prove that, for any kernel and any slope at the origin, there do exist travelling wave solutions (actually those which are "rapid") of the nonlocal Fisher ... More
Exhaustive Search for Small Dimension Recursive MDS Diffusion Layers for Block Ciphers and Hash FunctionsMay 15 2013This article presents a new algorithm to find MDS matrices that are well suited for use as a diffusion layer in lightweight block ciphers. Using an recursive construction, it is possible to obtain matrices with a very compact description. Classical field ... More
Energy decay for a locally undamped wave equationNov 26 2014We study the decay rate for the energy of solutions of a damped wave equation in a situation where the Geometric Control Condition is violated. We assume that the set of undamped trajectories is a flat torus of positive codimension and that the metric ... More
Identifying roles in an IP network with temporal and structural densityJun 19 2014Jul 04 2016Captures of IP traffic contain much information on very different kinds of activities like file transfers, users interacting with remote systems, automatic backups, or distributed computations. Identifying such activities is crucial for an appropriate ... More
Derivatives of the tree functionOct 28 2013We study some sequences of polynomials that appear when we consider the successive derivatives of the tree function (or Lambert's W function). We show in particular that they are related with a generalization of Cayley trees, called Greg trees. Besides ... More
Moduli of Galois p-covers in mixed characteristicsSep 21 2010Sep 22 2010We define a proper moduli stack for degree $p$ covers $f:Y \to \cX$ where $\cX$ is a twisted stable curve in the sense of [5] and [4], and $Y$ is a stable curve which via $f$ is a torsor over $\cX$ under a finite flat group scheme $\cG \to \cX$.
Garside-theoretic analysis of Burau representationsJan 12 2014Jan 16 2014We establish relations between both the classical and the dual Garside structures of the braid group and the Burau representation. Using the classical structure, we formulate a non-vanishing criterion for the Burau representation of the 4-strand braid ... More
Data analysis methods for the cosmic microwave backgroundAug 10 2007Jun 10 2008In this review, we give an overview of some of the major aspects of data reduction and analysis for the cosmic microwave background (CMB). Since its prediction and discovery in the last century, the CMB radiation has proven itself to be one of our most ... More
A 3D Finite Element model of the face for simulation in plastic and maxillo-facial surgeryJun 26 2006This paper introduces a new Finite Element biomechanical model of the human face, which has been developed to be integrated into a simulator for plastic and maxillo-facial surgery. The idea is to be able to predict, from an aesthetic and functional point ... More
On the rigidity of a hard sphere glass near random close packingDec 09 2005Oct 27 2006We study theoretically and numerically the microscopic cause of the mechanical stability of hard sphere glasses near their maximum packing. We show that, after coarse-graining over time, the hard sphere interaction can be described by an effective potential ... More
Smooth type II blow up solutions to the four dimensional energy critical wave equationOct 08 2010We exhibit $\mathcal C^{\infty}$ type II blow up solutions to the focusing energy critical wave equation in dimension $N=4$. These solutions admit near blow up time a decomposiiton $u(t,x)=1/l(t)(Q+e(t))(x/l(t)}}$ with $|e(t),\pa_t e(t)|_{\dot{H}^1\times ... More
Paramagnetic response of muscle-type systemsOct 11 2015We provide a prototypical description of mechanically-induced collective conformational change (folding), relevant in a variety of biological contexts from muscle contraction to hair cell gating and integrin binding. Our study is inspired by the seminal ... More
Marginal Stability in Structural, Spin and Electron GlassesJun 30 2014We revisit the concept of marginal stability in glasses, and determine its range of applicability in the context of avalanche-type response to slow external driving. We argue that there is an intimate connection between a pseudo-gap in the distribution ... More
Quantitative unique continuation for operators with partially analytic coefficients. Application to approximate control for wavesJun 13 2015In this article, we first prove quantitative estimates associated to the unique continuation theorems for operators with partially analytic coefficients of Tataru, Robbiano-Zuily and H\"ormander. We provide local stability estimates that can be propagated, ... More