Construction de valeurs propres doubles du laplacien de Hodge-de Rham

On any compact manifold of dimension greater than 3, we exhibit a metric whose first positive eigenvalue for the Laplacian acting on p-form is of multiplicity 2. As a corollary, we prescribe the volume and any finite part of the spectrum of the Hodge Laplacian with multiplicity 1 or 2.Comment: 14 pages, 4 figures, in french. v2: new example

Isotropic Surface Remeshing

International audienceThis paper proposes a new method for isotropic remeshing of tri- angulated surface meshes. Given a triangulated surface mesh to be resampled and a user-specified density function defined over it, we first distribute the desired number of samples by generalizing error diffusion, commonly used in image halftoning, to work directly on mesh triangles and feature edges. We then use the resulting sam- pling as an initial configuration for building a weighted centroidal Voronoi tessellation in a conformal parameter space, where the specified density function is used for weighting. We finally create the mesh by lifting the corresponding constrained Delaunay trian- gulation from parameter space. A precise control over the sampling is obtained through a flexible design of the density function, the latter being possibly low-pass filtered to obtain a smoother grada- tion. We demonstrate the versatility of our approach through vari- ous remeshing examples

Semiclassical theory for many-body Fermionic systems

We present a treatment of many-body Fermionic systems that facilitates an expression of the well-known quantities in a series expansion of the Planck's constant. The ensuing semiclassical result contains to a leading order of the response function the classical time correlation function of the observable followed by the Weyl-Wigner series, on top of these terms are the periodic-orbit correction terms. The treatment given here starts from linear response assumption of the many-body theory and in its connection with semiclassical theory, it makes no assumption of the integrability of classical dynamics underlying the one-body quantal system. Applications of the framework are also discussed.Comment: 18 pages, Te

VERS L'OPTIMISATION DYNAMIQUE EN TEMPS REEL DE SYSTEMES THERMIQUES MULTI-ENERGIE INCLUANT LE SOLAIRE THERMIQUE

International audienc

Centroidal Voronoi diagrams for isotropic surface remeshing

International audienceThis paper proposes a new method for isotropic remeshing of triangulated surface meshes. Given a triangulated surface mesh to be resampled and a user-specified density function defined over it, we first distribute the desired number of samples by generalizing error diffusion, commonly used in image halftoning, to work directly on mesh triangles and feature edges. We then use the resulting sampling as an initial configuration for building a weighted centroidal Voronoi diagram in a conformal parameter space, where the specified density function is used for weighting. We finally create the mesh by lifting the corresponding constrained Delaunay triangulation from parameter space. A precise control over the sampling is obtained through a flexible design of the density function, the latter being possibly low-pass filtered to obtain a smoother gradation. We demonstrate the versatility of our approach through various remeshing examples

Projet Collectif de Recherche triennal 2020-2022, « La Confluence Saône / Doubs à l'âge du Fer » (VIe s. av. J.-C. au Ier s. de notre ère). Rapport intermédiaire 2020

Le PCR : La confluence Saône-Doubs à l’âge du Fer (VIe s. av. J.-C. au Ier siècle de notre ère), coordonné par Matthieu Thivet et Émilie Dubreucq, vise à relancer une dynamique de recherche sur un secteur géographique clé : la confluence de la Saône et du Doubs, située en plein coeur de la Bourgogne, à une vingtaine de kilomètres au nord de Chalon-sur-Saône. Nous souhaitons travailler d’une part, sur les interactions hommes/environnement dans la longue durée (VIe-Ier siècle), afin de mieux percevoir le rôle joué par la zone de confluence dans l’émergence d’un important pôle de peuplement à l’âge du fer. D’autre part nous aborderons la question de la proto-urbanisation et des modalités de développement des agglomérations ouvertes à spécialisation artisanale et commerciale au cours de l'âge du Fer, dont le Verdunois peut s'enorgueillir de posséder deux cas emblématiques : Bragny-sur-Saône « Sous Moussière » et Verdun-sur-le-Doubs « Petit chauvort ». Pour répondre aux multiples problématiques soulevées, la force du programme repose sur son interdisciplinarité, en compilant des approches à la fois documentaires, archéologiques, géophysiques et spatiales

Distribution of Achromobacter species in 12 French cystic fibrosis centers in 2020 by a retrospective MALDI-TOF MS spectrum analysis

International audienceAchromobacter spp. are nonfermenting Gram-negative bacilli mainly studied among cystic fibrosis (CF) patients. The identification of the 19 species within the genus is time-consuming (nrdA-sequencing), thus data concerning the distribution of the species are limited to specific studies. Recently, we built a database using MALDI-TOF mass spectrometry (MS) (Bruker) that allows rapid and accurate species identification and detection of the multiresistant epidemic clones: A xylosoxidans ST137 spreading among CF patients in various French and Belgium centers, and A. ruhlandii DES in Denmark. Here, we first assessed whether species identification could be achieved with our database solely by analysis of MS spectra without availability of isolates. Then, we conducted a multicentric study describing the distribution of Achromobacter species and of the clone ST137 among French CF centers. We collected and analyzed with our local database the spectra of Achromobacter isolates from 193 patients (528 samples) from 12 centers during 2020. In total, our approach enabled to conclude for 502/528 samples (95.1%), corresponding to 181 patients. Eleven species were detected, only five being involved in chronic colonization, A. xylosoxidans (86.4%), A. insuavis (9.1%), A. mucicolens (2.3%), A. marplatensis (1.1%) and A. genogroup 3 (1.1%). This study confirmed the high prevalence of A. xylosoxidans in chronic colonizations and the circulation of the clone A. xylosoxidans ST137 in France: four patients in two centers. The present study is the first to report the distribution of Achromobacter species from CF patients samples using retrospective MALDI-TOF/MS data. This easy approach could enable future large-scale epidemiological studies

Colloquium: Proteins: The physics of amorphous evolving matter

Protein is matter of dual nature. As a physical object, a protein molecule is a folded chain of amino acids with diverse biochemistry. But it is also a point along an evolutionary trajectory determined by the function performed by the protein within a hierarchy of interwoven interaction networks of the cell, the organism, and the population. A physical theory of proteins therefore needs to unify both aspects, the biophysical and the evolutionary. Specifically, it should provide a model of how the DNA gene is mapped into the functional phenotype of the protein. Several physical approaches to the protein problem are reviewed, focusing on a mechanical framework which treats proteins as evolvable condensed matter: Mutations introduce localized perturbations in the gene, which are translated to localized perturbations in the protein matter. A natural tool to examine how mutations shape the phenotype are Green's functions. They map the evolutionary linkage among mutations in the gene (termed epistasis) to cooperative physical interactions among the amino acids in the protein. The mechanistic view can be applied to examine basic questions of protein evolution and design