Results for "Nicolas Altobelli"

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Interstellar Dust in the Solar SystemJun 21 2007The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse almost perpendicular to the ecliptic plane (inclination 79 deg, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. The in-situ dust ... More
Dissolution on Titan and on Earth: Towards the age of Titan's karstic landscapesMay 29 2015Titan's polar surface is dotted with hundreds of lacustrine depressions. Based on the hypothesis that they are karstic in origin, we aim at determining the efficiency of surface dissolution as a landshaping process on Titan, in a comparative planetology ... More
The Cosmic Dust Analyzer onboard Cassini: ten years of discoveriesFeb 13 2018The interplanetary space probe Cassini/Huygens reached Saturn in July 2004 after seven years of cruise phase. The Cosmic Dust Analyzer (CDA) measures the interplanetary, interstellar and planetary dust in our solar system since 1999 and provided unique ... More
Clusters of proteins in bio-membranes: insights into the roles of interaction potential shapes and of protein diversityJun 07 2011It has recently been proposed that proteins embedded in lipidic bio-membranes can spontaneously self-organize into stable small clusters, or membrane nano-domains, due to the competition between short-range attractive and longer-range repulsive forces ... More
Partial list of bipartite Bell inequalities with four binary settingsNov 21 2007Jan 30 2008We give a partial list of 26 tight Bell inequalities for the case where Alice and Bob choose among four two-outcome measurements. All tight Bell inequalities with less settings are reviewed as well. For each inequality we compute numerically the maximal ... More
High-accuracy first-principles determination of the structural, vibrational and thermodynamical properties of diamond, graphite, and derivativesDec 22 2004The structural, dynamical, and thermodynamical properties of diamond, graphite and layered derivatives (graphene, rhombohedral graphite) are computed using a combination of density-functional theory (DFT) total-energy calculations and density-functional ... More
Quantum cryptography with and without entanglementDec 01 2003Quantum cryptography is reviewed, first using entanglement both for the intuition and for the experimental realizations. Next, the implementation is simplified in several steps until it becomes practical. At this point entanglement has disappeared. This ... More
Dark soliton past a finite-size obstacleJan 04 2005Sep 05 2005We consider the collision of a dark soliton with an obstacle in a quasi-one-dimensional Bose condensate. We show that in many respects the soliton behaves as an effective classical particle of mass twice the mass of a bare particle, evolving in an effective ... More
Anderson localization of elementary excitations in a one dimensional Bose-Einstein condensateFeb 27 2006Aug 01 2006We study the elementary excitations of a transversely confined Bose-Einstein condensate in presence of a weak axial random potential. We determine the localization length (i) in the hydrodynamical low energy regime, for a domain of linear densities ranging ... More
Interstellar Dust Module for the ESA Meteoroid ModelApr 17 2001The ESA meteoroid model predicts impacts of meteoroids in the mass range between $10^{-18}$ to $10^0$ g on spacecraft surfaces. It covers heliocentric distances from 0.3 to 20 AU. Measurements of the dust detector on board the highly successful joint ... More
On the initial conditions and solutions of the semiclassical Einstein equations in a cosmological scenarioJan 06 2010Jul 07 2010In this paper we shall discuss the backreaction of a massive quantum scalar field on the curvature, the latter treated as a classical field. Furthermore, we shall deal with this problem in the realm of cosmological spacetimes by analyzing the Einstein ... More
Large deviations for singular and degenerate diffusion models in adaptive evolutionMar 13 2009In the course of Darwinian evolution of a population, punctualism is an important phenomenon whereby long periods of genetic stasis alternate with short periods of rapid evolutionary change. This paper provides a mathematical interpretation of punctualism ... More
In-Place Longest Common ExtensionsAug 17 2016Nov 02 2016Longest Common Extension (LCE) queries are a fundamental sub-routine in many string-processing algorithms, including (but not limited to) suffix-sorting, string matching, compression, and identification of repeats and palindrome factors. A LCE query takes ... More
ROSAT-HRI detection of the Class I protostar YLW16A in the rho Ophiuchi dark cloudMar 01 2001I analyze unpublished or partially published archival ROSAT data of the rho Ophiuchi dark cloud. This set of seven overlapping ROSAT HRI pointings, composed of eight ~one-hour exposures, detects mainly the X-ray brightest T Tauri stars of this star-forming ... More
On pathwise uniqueness for stochastic differential equations driven by stable Lévy processesNov 02 2010We study a one-dimensional stochastic differential equation driven by a stable L\'evy process of order $\alpha$ with drift and diffusion coefficients $b,\sigma$. When $\alpha\in (1,2)$, we investigate pathwise uniqueness for this equation. When $\alpha\in ... More
Origin of the Proton-to-Helium Ratio Anomaly in Cosmic RaysNov 13 2015Dec 03 2015Recent data on Galactic cosmic rays (CRs) revealed that the helium energy spectrum is harder than the proton spectrum. The AMS experiment has now reported that the proton-to-helium ratio as function of rigidity $R$ (momentum-to-charge ratio) falls off ... More
The Axelrod model for the dissemination of culture revisitedApr 02 2010May 07 2012This article is concerned with the Axelrod model, a stochastic process which similarly to the voter model includes social influence, but unlike the voter model also accounts for homophily. Each vertex of the network of interactions is characterized by ... More
Two-scale multitype contact process: coexistence in spatially explicit metapopulationsFeb 27 2010It is known that the limiting behavior of the contact process strongly depends upon the geometry of the graph on which particles evolve: while the contact process on the regular lattice exhibits only two phases, the process on homogeneous trees exhibits ... More
Dominating surface group representations and deforming closed AdS 3-manifoldsMar 28 2014Sep 22 2014In a previous paper by Deroin-Tholozan, the authors construct a map $\mathbf{\Psi}_\rho$ from the Teichm\"uller space of $S$ to itself and prove that, when $M$ has sectional curvature $\leq -1$, the image of $\mathbf{\Psi}_\rho$ lies (almost always) in ... More
Implicitization of rational mapsSep 07 2011Motivated by the interest in computing explicit formulas for resultants and discriminants initiated by B\'ezout, Cayley and Sylvester in the eighteenth and nineteenth centuries, and emphasized in the latest years due to the increase of computing power, ... More
Fast simulation of truncated Gaussian distributionsJan 30 2012We consider the problem of simulating a Gaussian vector X, conditional on the fact that each component of X belongs to a finite interval [a_i,b_i], or a semi-finite interval [a_i,+infty). In the one-dimensional case, we design a table-based algorithm ... More
Decomposing Berge graphs and detecting balanced skew partitionsSep 03 2013A hole in a graph is an induced cycle on at least four vertices. A graph is Berge if it has no odd hole and if its complement has no odd hole. In 2002, Chudnovsky, Robertson, Seymour and Thomas proved a decomposition theorem for Berge graphs saying that ... More
On the differential structure of metric measure spaces and applicationsMay 30 2012May 21 2013The main goals of this paper are: i) To develop an abstract differential calculus on metric measure spaces by investigating the duality relations between differentials and gradients of Sobolev functions. This will be achieved without calling into play ... More
Contribution to the asymptotic analysis of the Landau-de Gennes functionalDec 09 2008Jun 04 2009In this paper we are interested in the Landau-de Gennes functional introduced to study the transition between the smectic and nematic phases of a liquid crystal. We define a reduced functional by constraining the director field to satisfy a non-homogeneous ... More
cK\cent, a model to reason on learners' conceptionsAug 24 2013Understanding learners' understanding is a key requirement for an efficient design of teaching situations and learning environments, be they digital or not. This keynote outlines the modeling framework cK\cent (conception, knowing, concept) created with ... More
Optimization of the Cherenkov signal from TeO$_{2}$ bolometersApr 06 2016The most sensitive process able to probe the Majorana nature of neutrinos and discover Lepton Number Violation is the neutrino-less double beta decay (0$\nu$DBD). A novel approach able to improve the sensitivity of the current bolometric experiments searching ... More
On numerical integration by the shift and application to Wiener spaceOct 18 2006The aim of this study is to clarify the consequences of recent theoretical results for the numerical computation of expectation by the shift method, and in particular to yield sufficient criteria for the existence of speed of convergence of the type `iterated ... More
Reconstruction of Epsilon-Machines in Predictive Frameworks and Decisional StatesFeb 03 2009Jun 06 2011This article introduces both a new algorithm for reconstructing epsilon-machines from data, as well as the decisional states. These are defined as the internal states of a system that lead to the same decision, based on a user-provided utility or pay-off ... More
On the regularization process for Ariki-Koike algebrasJan 17 2013Jan 23 2013The aim of this note is to study a generalization of theorems by James and Fayers on the modular representations of the symmetric group and its Hecke algebra to the case of the complex reflection groups of type $G(l,1,n)$ and the associated Ariki-Koike ... More
Unveiling the nature of INTEGRAL sources through optical spectroscopyApr 22 2006Since its launch on October 2002 the INTEGRAL satellite is performing an deep survey of the hard X-ray sky with unprecedented sensitivity and positional accuracy. This allowed pinpointing, through positional cross-correlation with catalogs at longer wavelengths, ... More
Companion forms and explicit computation of PGL2 number fields with very little ramificationNov 04 2016In previous works, we described algorithms to compute the number field cut out by the mod l representation attached to a form of level N=1. In this article, we explain how these algorithms can be generalised to forms of higher level; as an application, ... More
Lattice determination of fBd, fBs, and xiFeb 08 2011In this talk I summarize the recent lattice determinations of the decay constants and of the bag parameters of the heavy-light and heavy-strange neutral mesons.
La conjecture des sous-groupes de surfaces (d'après Jeremy Kahn et Vladimir Markovic)Jul 13 2012This is the text of my Bourbaki seminar on the proof of the surface subgroup conjecture by Jeremy Kahn and Vladimir Markovic.
Remarks on a special value of the Selberg zeta functionFeb 24 2009Feb 25 2009Let $\CmZ_{Y_0(N)}$ be the constant term of the logarithmic derivative at $s=1$ of the Selberg zeta function of the modular curve $Y_0(N)$. Jorgenson and Kramer established the bound $\CmZ_{Y_0(N)}=O_\epsilon(N^\epsilon)$, $\epsilon>0$ by relating it ... More
Extensions of Formal Hodge StructuresMay 12 2009We define and study the properties of the category ${\sf FHS}_n$ of formal Hodge structure of level $\le n$ following the ideas of L. Barbieri-Viale who discussed the case of level $\le 1$. As an application we describe the generalized Albanese variety ... More
Constructible representations and basic sets in type BNov 06 2009Nov 13 2009We study the parametrizations of simple modules provided by the theory of basic sets for all finite Weyl groups. In the case of type B, we show the existence of basic sets for the matrices of constructible representations. Then we study bijections between ... More
Smoothness of the law of some one-dimensional jumping S.D.E.s with non-constant rate of jumpApr 30 2007We consider a one-dimensional jumping Markov process $\{X^x_t\}_{t \geq 0}$, solving a Poisson-driven stochastic differential equation. We prove that the law of $X^x_t$ admits a smooth density for $t>0$, under some regularity and non-degeneracy assumptions ... More
The model magnetic Laplacian on wedgesSep 24 2013We study a model Schr\"odinger operator with constan tmagnetic field on an infinite wedge with natural boundary conditions. This problem is related to the semiclassical magnetic Laplacian on 3d domains with edges. We show that the ground energy is lower ... More
Smoothing effect for Schrödinger boundary value problemsOct 17 2002Aug 25 2003We show the necessity of the non trapping condition for the plain smoothing effect ($H^{1/2}$) for Schr\"odinger equation with Dirichlet boundary conditions in exterior problems. We also give a class of trapped obstacles (Ikawa's example) for which we ... More
The Dual Origin of the Terrestrial AtmosphereJun 28 2003The origin of the terrestrial atmosphere is one of the most puzzling enigmas in the planetary sciences. It is suggested here that two sources contributed to its formation, fractionated nebular gases and accreted cometary volatiles. During terrestrial ... More
Densité de points et minoration de hauteurApr 03 2003Jan 02 2004We obtain a lower bound for the normalised height of a non-torsion subvariety $V$ of a C.M. abelian variety. This lower bound is optimal in terms of the geometric degree of $V$, up to a power of a ``log''. We thus extend the results of F. Amoroso and ... More
Geometric Invariant Theory and Generalized Eigenvalue ProblemApr 17 2007Mar 02 2009Let $H$ be a connected reductive subgroup of a complex connected reductive group $G$. Fix maximal tori and Borel subgroups of $H$ and $G$. Consider the pairs $(V,V')$ of irreducible representations of $H$ and $G$ such that $V$ is a submodule of $V'$. ... More
On the quantum Horn problemOct 28 2013Let $K$ be a compact, connected, simply-connected simple Lie group. Given two conjugacy classes $\Orb_1$ and $\Orb_2$ in $K$, we consider the multiplicative Horn question: What conjugacy classes are contained in $\Orb_1\cdot\Orb_2$? It is known that answering ... More
Eigencones and the PRV conjectureOct 05 2009Nov 03 2009Let $G$ be a complex semisimple simply connected algebraic group. Given two irreducible representations $V_1$ and $V_2$ of $G$, we are interested in some components of $V_1\otimes V_2$. Consider two geometric realizations of $V_1$ and $V_2$ using the ... More
Estimates of the best Sobolev constant of the embedding of $BV(Ω)$ into $L^1(\partialΩ)$ and related shape optimization problemsJun 07 2007In this paper we find estimates for the optimal constant in the critical Sobolev trace inequality $\lambda_1(\Omega)\|u\|_{L^1(\partial\Omega)} \le \|u\|_{W^{1,1}(\Omega)}$ that are independent of $\Omega$. This estimates generalize those of \cite{BS} ... More
Solar and planetary oscillation control on climate change: hind-cast, forecast and a comparison with the CMIP5 GCMsJul 14 2013Global surface temperature records (e.g. HadCRUT4) since 1850 are characterized by climatic oscillations synchronous with specific solar, planetary and lunar harmonics superimposed on a background warming modulation. The latter is related to a long millennial ... More
The complex planetary synchronization structure of the solar systemJan 16 2014The complex planetary synchronization structure of the solar system, which since Pythagoras of Samos (ca. 570-495 BC) is known as the music of the spheres, is briefly reviewed from the Renaissance up to contemporary research. Copernicus' heliocentric ... More
Convergence in $L^p$ for Feynman path integralsMar 19 2015Mar 22 2015We consider a class of Schrodinger equations with time-dependent smooth magnetic and electric potentials having a growth at infinity at most linear and quadratic, respectively. We study the convergence in $L^p$ with loss of derivatives, $1<p<\infty$, ... More
Breakdown of superfluidity of an atom laser past an obstacleJun 14 2002The 1D flow of a continuous beam of Bose-Einstein condensed atoms in the presence of an obstacle is studied as a function of the beam velocity and of the type of perturbing potential (representing the interaction of the obstacle with the atoms of the ... More
Time Really Passes, Science Can't Deny ThatJan 30 2016Today's science provides quite a lean picture of time as a mere geometric evolution parameter. I argue that time is much richer. In particular, I argue that besides the geometric time, there is creative time, when objective chance events happen. The existence ... More
Finite-Type Invariants of Order One for Framed Virtual KnotsSep 24 2015Oct 11 2016A. Henrich proved the existence of the universal finite-type invariant of order one for virtual knots. We extend the construction and the methods of her paper to framed virtual knots. To do so, we introduce the notions of virtual strings and based matrices ... More
Quantum CommunicationJul 18 2015Quantum Communication is the art of transferring an unknown quantum state from one location, Alice, to a distant one, Bob. This is a non-trivial task because of the quantum no-cloning theorem which prevents one from merely using only classical means.
Nonconvex phase synchronizationJan 22 2016Aug 22 2016We estimate $n$ phases (angles) from noisy pairwise relative phase measurements. The task is modeled as a nonconvex least-squares optimization problem. It was recently shown that this problem can be solved in polynomial time via convex relaxation, under ... More
On some remarkable congruences between two elliptic curvesMay 17 2016May 31 2016We exhibit two non-isogenous rational elliptic curves with $17$-torsion subgroups isomorphic as Galois modules.
etab Decay into Two PhotonsSep 24 2002We discuss the theoretical predictions for the two photon decay width of the pseudoscalar etab meson. Predictions from potential models are examined. It is found that various models are in good agreement with each other. Results for etab are also compared ... More
Teaching an Old Elephant New TricksSep 09 2009In recent years, column stores (or C-stores for short) have emerged as a novel approach to deal with read-mostly data warehousing applications. Experimental evidence suggests that, for certain types of queries, the new features of C-stores result in orders ... More
The VERITAS Extragalactic Science ProgramNov 01 2011VERITAS is an array of four 12-m diameter imaging atmospheric-Cherenkov telescopes located in southern Arizona. Its aim is to study the very high energy (VHE: E > 100 GeV) gamma-ray emission from astrophysical objects. The study of Active Galactic Nuclei ... More
Sliding phase in randomly stacked 2D superfluids/superconductorsApr 03 2012Sep 15 2012Using large scale quantum Monte Carlo simulations of lattice bosonic models, we precisely investigate the effect of weak Josephson tunneling between 2D superfluid or superconducting layers. In the clean case, the Kosterlitz-Thouless transition immediately ... More
Quantum ergodicity of boundary values of eigenfunctions: A control theory approachJan 30 2003Consider $M$, a bounded domain in ${\mathbb R}^d$, which is a Riemanian manifold with piecewise smooth boundary and suppose that the billiard associated to the geodesic flow reflecting on the boundary acording to the laws of geometric optics is ergodic. ... More
The intergalactic medium in the cosmic webOct 01 2014The intergalactic medium (IGM) accounts for ~90% of baryons at all epochs and yet its three dimensional distribution in the cosmic web remains mostly unknown. This is so because the only feasible way to observe the bulk of the IGM is through intervening ... More
Polymer pinning at an interfaceApr 22 2005In this article, I study the localization transition of an hydrophobic homopolymer in interaction with an interface between oil and water. To that aim I consider a model in which the trajectories of a simple random walk play the role of the possible configurations ... More
Decomposition of symplectic vector fields with respect to a fibration in lagrangian toriMar 24 2004Given a fibration of a symplectic manifold by lagrangian tori, we show that each symplectic vector field splits into two parts : the first is Hamiltonian and the second is symplectic and preserves the fibration. We then show an application of this result ... More
Intersections of Lagrangian submanifolds and the Mel'nikov 1-formMay 25 2005Mar 16 2006We make explicit the geometric content of Mel'nikov's method for detecting heteroclinic points between transversally hyperbolic periodic orbits. After developing the general theory of intersections for pairs of family of Lagrangian submanifolds constrained ... More
A semi-classical K.A.M. theoremMar 25 2004May 24 2005We consider a semi-classical completely integrable system defined by a $\hbar$-pseudodifferential operator $\hat{H}$ on the torus $\mathbb{T}^{d}$. In order to study perturbed operators of the form $\hat{H}+\hbar^{\kappa}\hat{K}$, where $\hat{K}$ is an ... More
The inverted pendulum, interface phonons and optic Tamm statesOct 11 2011The propagation of waves in periodic media is related to the parametric oscillators. We transpose the possibility that a parametric pendulum oscillates in the vicinity of its unstable equilibrium positions to the case of waves in lossless unidimensional ... More
Effective Invariant Theory of Permutation Groups using Representation TheoryNov 03 2015Using the theory of representations of the symmetric group, we propose an algorithm to compute the invariant ring of a permutation group. Our approach have the goal to reduce the amount of linear algebra computations and exploit a thinner combinatorial ... More
Femtoscopy and energy-momentum conservation effects in proton-proton collisions at 900 GeV in ALICESep 16 2010Two particle correlations are used to extract information about the characteristic size of the system for proton-proton collisions at 900 GeV measured by the ALICE (A Large Ion Collider experiment) detector at CERN. The correlation functions obtained ... More
A topological characterization of the Moufang property for compact polygonsNov 25 2014Jul 15 2016We prove a purely topological characterization of the Moufang property for disconnected compact polygons in terms of convergence groups. As a consequence, we recover the fact that a locally finite thick affine building of rank 3 is a Bruhat-Tits building ... More
Annular Bose-Einstein Condensates in the Lowest Landau LevelSep 10 2010Nov 17 2010A rotating superfluid such as a Bose-Einstein condensate is usually described by the Gross-Pitaevskii (GP) model. An important issue is to determine from this model the properties of the quantized vortices that a superfluid nucleates when set into rotation. ... More
Deux remarques sur le probleme de Lehmer sur les varietes abeliennesFeb 13 2004Let $A/K$ be an abelian variety over a number field $K$. We prove in this article that a good lower bound (in terms of the degree $[K(P):K]$) for the N\'eron-Tate height of the points $P$ of infinite order modulo every strict abelian subvarieties of $A$ ... More
Finite-type Invariants of Long and Framed Virtual KnotsOct 11 2016Oct 13 2016We generalize three invariants, first discovered by A. Henrich, to the long and/or framed virtual knot case. These invariants are all finite-type invariants of order one, and include a universal one. The generalization will require us to extend the notion ... More
Late time cosmology with LISA: probing the cosmic expansion with massive black hole binary mergers as standard sirensDec 08 2016This paper summarises the potential of the LISA mission to constrain the expansion history of the universe using massive black hole binary mergers as gravitational wave standard sirens. After briefly reviewing the concept of standard siren, the analysis ... More
Chen-Ruan cohomology of M_{1,n} and \bar{M}_{1,n}Oct 15 2008Sep 18 2012In this work we compute the Chen--Ruan cohomology and the stringy Chow ring of the moduli spaces of smooth and stable $n$-pointed curves of genus 1. We suggest a definition for an Orbifold Tautological Ring in genus 1, which is both a subring of the Chen--Ruan ... More
Local study of stable module categories via tensor triangulated geometryOct 11 2016Oct 19 2016We investigate the particular properties of the stable category of modules over a finite dimensional cocommutative graded connected Hopf algebra $A$, via tensor-triangulated geometry. This study requires some mild conditions on the Hopf algebra $A$ under ... More
Large solutions for fractional Laplacian operatorsNov 02 2015The thesis studies linear and semilinear Dirichlet problems driven by different fractional Laplacians. The boundary data can be smooth functions or also Radon measures. The goal is to classify the solutions which have a singularity on the boundary of ... More
Large $s$-harmonic functions and boundary blow-up solutions for the fractional LaplacianOct 11 2013Nov 18 2013We present a notion of weak solution for the Dirichlet problem driven by the fractional Laplacian, following the Stampacchia theory. Then, we study semilinear problems on bounded domains $\Omega$ with two different boundary conditions at the same time: ... More
An extension to the Wiener space of the arbitrary functions principleOct 17 2006The arbitrary functions principle says that the fractional part of $nX$ converges stably to an independent random variable uniformly distributed on the unit interval, as soon as the random variable $X$ possesses a density or a characteristic function ... More
Dirichlet forms in simulationOct 16 2006Equipping the probability space with a local Dirichlet form with square field operator $\Gamma$ and generator $A$ allows to improve Monte Carlo computations of expectations, densities, and conditional expectations, as soon as we are able to simulate a ... More
Temporal Lorentzian Spectral TriplesOct 24 2012Aug 25 2014We present the notion of temporal Lorentzian spectral triple which is an extension of the notion of pseudo-Riemannian spectral triple with a way to ensure that the signature of the metric is Lorentzian. A temporal Lorentzian spectral triple corresponds ... More
The Lorentzian distance formula in noncommutative geometryOct 30 2017Jan 24 2018For almost twenty years, a search for a Lorentzian version of the well-known Connes' distance formula has been undertaken. Several authors have contributed to this search, providing important milestones, and the time has now come to put those elements ... More
Bounded multiplicative Toeplitz operators on sequence spacesJan 29 2018In this paper, we study the linear mapping which sends the sequence $x=(x_n)_{n \in \mathbb{N}}$ to $y=(y_n)_{n \in \mathbb{N}}$ where $y_n = \sum_{k=1}^\infty f(n/k)x_k$ for $f: \mathbb{Q}^+ \to \mathbb{C}$. This operator is the multiplicative analogue ... More
Adaptive Discrimination Scheme for Quantum Pulse Position Modulation SignalsJun 29 2013Jan 08 2014In the communication scenario, we consider the problem of the discrimination between the signals of the Quantum Pulse Position Modulation. We propose a receiver scheme that employs repeated local measurements in distinct temporal slots within the symbol ... More
New derived symmetries of some hyperkähler varietiesDec 02 2011Aug 18 2016We construct a new autoequivalence of the derived category of the Hilbert scheme of n points on a K3 surface, and of the variety of lines on a smooth cubic 4-fold. For Hilb^2 and the variety of lines, we use the theory of spherical functors; to deal with ... More
Some Ontological Principles for Designing Upper Level Lexical ResourcesSep 09 1998The purpose of this paper is to explore some semantic problems related to the use of linguistic ontologies in information systems, and to suggest some organizing principles aimed to solve such problems. The taxonomic structure of current ontologies is ... More
On the bounded cohomology of semi-simple groups, S-arithmetic groups and productsOct 29 2007We prove vanishing results for Lie groups and algebraic groups (over any local field) in bounded cohomology. The main result is a vanishing below twice the rank for semi-simple groups. Related rigidity results are established for S-arithmetic groups and ... More
Perfect graphs: a surveyJan 22 2013May 22 2015Perfect graphs were defined by Claude Berge in the 1960s. They are important objects for graph theory, linear programming and combinatorial optimization. Claude Berge made a conjecture about them, that was proved by Chudnovsky, Robertson, Seymour and ... More
Neutron conduction in the inner crust of a neutron star in the framework of the band theory of solidsMar 01 2012Even though the "free" neutrons in the inner crust of a neutron star are superfluid, they are still strongly coupled to nuclei due to non-dissipative entrainment effects. These effects have been systematically studied in all regions of the inner crust ... More
Opinion dynamics with confidence threshold: an alternative to the Axelrod modelFeb 27 2010Dec 25 2010The voter model and the Axelrod model are two of the main stochastic processes that describe the spread of opinions on networks. The former includes social influence, the tendency of individuals to become more similar when they interact, while the latter ... More
Inhomogeneous diffusion model for recent data on high-energy cosmic raysOct 30 2015The AMS Collaboration has recently released precision data on cosmic ray (CR) leptons and protons at high energies. Interesting progresses have also been made on the measurement of CR nuclei, such as the boron-to-carbon ratio or the lithium spectrum, ... More
Origin of the spectral upturn in the cosmic-ray C/Fe and O/Fe ratiosSep 18 2015The observed spectrum of Galactic cosmic rays has several exciting features such as the rise in the positron fraction above ~10 GeV of energy and the spectral hardening of protons and helium at ~300 GeV/nucleon of energy. The ATIC-2 experiment has recently ... More
The splitting theorem in non-smooth contextFeb 22 2013We prove that an infinitesimally Hilbertian CD(0,N) space containing a line splits as the product of $R$ and an infinitesimally Hilbertian CD(0,N-1) space. By `infinitesimally Hilbertian' we mean that the Sobolev space $W^{1,2}(X,d,m)$, which in general ... More
Tradeoffs for reliable quantum information storage in surface codes and color codesJan 28 2013The family of hyperbolic surface codes is one of the rare families of quantum LDPC codes with non-zero rate and unbounded minimum distance. First, we introduce a family of hyperbolic color codes. This produces a new family of quantum LDPC codes with non-zero ... More
Inclusive Hadronic Results at BaBar: ISR and Pentaquark SearchesOct 15 2005We present recent measurements of hadronic cross-sections from the BaBar experiment and report preliminary results on searches for pentaquark states.
A synthesis and a practical approach to complex systemsJun 15 2006Mar 05 2008This document is both a synthesis of current notions about complex systems, and a practical approach description. A disambiguation is proposed and exposes possible reasons for controversies related to causation and emergence. Theoretical considerations ... More
The Semisimplicity Conjecture for A-MotivesSep 01 2008We prove the semisimplicity conjecture for A-motives over finitely generated fields K. This conjecture states that the rational Tate modules V_p(M) of a semisimple A-motive M are semisimple as representations of the absolute Galois group of K. This theorem ... More
Optical telecom networks as weak measurements with post-selectionSep 05 2003In this work we establish a link between two apparently unrelated subjects: polarization effects in optical fibers and devices, and the quantum theory of weak measurements. We show that the abstract concept of weak measurements followed by post-selection, ... More
Theoreme de Dobrowolski-Laurent pour les extensions abeliennes sur une courbe elliptique a multiplication complexeFeb 13 2004Feb 16 2004Let E/K be an elliptic curve with complex multiplication and let $K^{ab}$ be the Abelian closure of $K$. We prove in this article that there exists a constant $c(E/K)$ such that : for all point $P\in E(\bar{K})-E_{tors}$, we have \[\hat{h}(P)\geq\frac{c(E/K)}{D}(\frac{\log ... More
Remarques a propos de l'operateur de Dirac cubiqueJun 21 2010Remarks on the Kostant Dirac operator In 1999, Kostant [Kos99] indroduces a Dirac operator D_g/h associated to any triple (g, h,B), where g is a complex Lie algebra provided with an ad g-invariant non degenerate nsymetric bilinear form B, and h is a Lie ... More
Large values of modular formsJul 25 2012Sep 19 2013We show that there are primitive holomorphic modular forms f of weight two and arbitrary large level N such that $|f(z)| \gg N^{1/4}$ for some point z. Thereby we disprove a folklore conjecture that the sup-norm of such forms would be as small as $N^{o(1)}$. ... More
Determination of the a0-a2 pion scattering length from K->pi+ pi0 pi0 decayMay 03 2004May 04 2004We present a new method for the determination of the pion-pion scattering lenght combination a0-a2, based on the study of the pi0-pi0 spectrum in K->pi+ pi0 pi0 in the vicinity of the pi+ pi- threshold. The method requires a minimum of theoretical input, ... More