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Nuclear effects on the transverse momentum spectra of charged particles in pPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV
No full textSubmitted to Eur. Phys. J. C - see paper for full list of authorsInternational audienceTransverse momentum spectra of charged particles are measured by the CMS experiment at the CERN LHC in pPb collisions at sqrt(s[NN]) =5.02 TeV, in the range 0.4 20 GeV compared to expectations from the pp reference. The enhancement is larger than predicted by perturbative quantum chromodynamic calculations that include antishadowing modifications of nPDFs
The reconstructed tree in the lineage-based model of protracted speciation
No full textInternational audienceA popular line of research in evolutionary biology is the use of time-calibrated phylogenies for the inference of diversification processes. This requires computing the likelihood of a given ultrametric tree as the reconstructed tree produced by a given model of diversification. Etienne and Rosindell in Syst Biol 61(2):204–213, (2012) proposed a lineage-based model of diversification, called protracted speciation, where species remain incipient during a random duration before turning good species, and showed that this can explain the slowdown in lineage accumulation observed in real phylogenies. However, they were unable to provide a general likelihood formula. Here, we present a likelihood formula for protracted speciation models, where rates at which species turn good or become extinct can depend both on their age and on time. Our only restrictive assumption is that speciation rate does not depend on species status. Our likelihood formula utilizes a new technique, based on the contour of the phylogenetic tree and first developed by Lambert in Ann Probab 38(1):348–395, (2010). We consider the reconstructed trees spanned by all extant species, by all good extant species, or by all representative species, which are either good extant species or incipient species representative of some good extinct species. Specifically, we prove that each of these trees is a coalescent point process, that is, a planar, ultrametric tree where the coalescence times between two consecutive tips are independent, identically distributed random variables. We characterize the common distribution of these coalescence times in some, biologically meaningful, special cases for which the likelihood reduces to an elegant analytical formula or becomes numerically tractable
Estimating π binding energy of N-Heterocyclic carbenes: The role of polarization
No full textInternational audienceIn this work, the tuneability of the π acceptor or donor properties of a set of N-heterocyclic carbenes (NHCs) with a wide spectrum of electronic characteristics is established by means of density functional theory and energy decomposition analysis (EDA) tools. Even though the main orbital interaction contribution to the NHC coordination is the σ donation, a significant contribution of the π interactions to the bond is observed. By means of carefully selected coordination sites, different contributions to the π interactions could be identified and isolated. It includes not only the well known back donation and donation interactions, but also the intrafragment polarization, which has not been considered in previous studies. This can be obtained through the use of the extended transition state method for EDA combined with the natural orbitals for chemical valence and the constrained space orbital variation analysis. The contributions vary with the position of the heteroatoms and the presence of exocyclic substituents; the donation/backdonation π interactions between NHC and the coordination site can range between 2 and 61% of the total π orbital interactions, while the rest is owed to intrafragment polarization. Our results do not only contribute to the understanding of the electronic structure of NHC-based complexes, giving ways to improve their catalytic properties, but also provide comprehension on the modelization methods used to study their donor–acceptor interactions
Interactions between interfacial sliding, diffuse micro cracking and crystal plasticity in polycrystalline rock salt investigated by 2D and 3D digital imagecorrelation
No full textInternational audienc
Les ennemis de l'emploi. Le chômage, fatalité ou nécessité ? Nouvelle édition
No full textNational audienceRevu et mis à jour par les auteurs, ce livre donne un éclairage entièrement nouveau sur le fonctionnement du marché du travail, la manière de penser le chômage et les politiques pour le combattre. Non, le chômage n'est pas une fatalité liée à la mondialisation et au capitalisme financier ; non, un bon salaire n'est pas toujours l'ennemi de l'emploi ; non, la législation sur les licenciements ne protège pas l'emploi ; non, la formation n'est pas le remède à tous les maux du chômeur ; non, le travail ne se «partage» pas, car il se recompose par d'incessants mouvements de création et de destruction d'emplois. Voilà ce qu'enseignent les recherches les plus récentes conduites en France et dans de nombreux pays. On n'a pas «tout essayé» pour combattre le chômage. Loin de là. Ce livre traque les ennemis de l'emploi et nous dit comment les abattre. À sa première parution, en 2004, sous le titre Le Chômage, fatalité ou nécessité ?, l'ouvrage a été salué par une critique unanime et a reçu le prix Mutations et Travail, le Prix européen du livre d'économie, le prix Manpower de l'ouvrage de ressources humaines en 2005 et le prix Zerilli-Marimo de l'Académie des sciences morales et politiques en 2006
On boundary layer scaling and detachment in two-dimensional incompressible uid for the high Reynolds number limit
No full textInternational audienceno abstrac
Towards Trace Metrics via Functor Lifting
No full textInternational audienceWe investigate the possibility of deriving metric trace semantics in a coalgebraic framework.First, we generalize a technique for systematically lifting functors from the category Set ofsets to the category PMet of pseudometric spaces, by identifying conditions under whichalso natural transformations, monads and distributive laws can be lifted. By exploiting somerecent work on an abstract determinization, these results enable the derivation of trace metricsstarting from coalgebras in Set. More precisely, for a coalgebra on Set we determinize it,thus obtaining a coalgebra in the Eilenberg-Moore category of a monad. When the monadcan be lifted to PMet, we can equip the final coalgebra with a behavioral distance. The tracedistance between two states of the original coalgebra is the distance between their images in thedeterminized coalgebra through the unit of the monad. We show how our framework appliesto nondeterministic automata and probabilistic automata
Microsphere model for strain-induced crystallization and three dimensional applications
No full textInternational audienceStrain-crystallising rubber exhibits interesting properties: for instance, fatigue lifetime is known to be modified by this microstructural evolution which dissipates energy and creates a strong anisotropic reinforcement. We develop herein a micro-sphere 3D constitutive model for such strain-crystallising rubber. It is based on a simplified 1D micromechanical model that we extend with a micro-sphere approach to a full thermodynamically consistent evolutive anisotropic model. A specific numerical strategy is then proposed. The model is assessed on several significative configurations and reproduces the main experimental features while predicting the evolution of anisotropy as a function of the loading history. We finally show that it can also predict the crystallised zone in front of a mode I crack
Étude de la reconnexion magnétique dans les plasmas turbulents à partir des données satellites
No full textMagnetic reconnection is a fundamental energy conversion process in plasma. It occurs in thin regions of strong current known as current sheets and results in particle heating and acceleration. In turbulence, which is ubiquitous in space plasma, magnetic reconnection has been observed to occur in small scale structures that form therein, and is thought to contribute to dissipation of turbulent energy at kinetic scales. For this work we examine data from the Cluster spacecraft in the Earth's magnetosheath, downstream of the quasi-parallel shock. The detection of ion-scale current sheets was performed by implementing the PartialVariance of Increments (PVI) method for multiple spacecraft. The properties of the observed current sheets were different for high (> 3) and low ( 3) structures that accounted for ~ 20% of the total. Those current sheets have high magneticshear (> 90degrees). In order to estimate the local heating occurring within those current sheets, a proxy of the electron temperature was obtained at high time resolution(125ms) from the partial distributions measured by Cluster. This allowed for the first time to study the localized electron heating within ion-scale currentsheets. The observed enhancement of the estimated electron temperature withinthe high PVI current sheets suggest that they are important for local electron heating and energy dissipation. We also examined measurements inside the diffusion region of a thin reconnecting current sheet. Multi-spacecraft observationsallow as to study electron distributions and wave activity at different distances from the x-line. Significant differences were observed in the electron populations as they were heated going through the current sheet. In particular electrons were heated in the direction parallel to the magnetic field in close proximity to thex-line, whereas no significant variation was observed in the perpendicular direction. However, the distribution was more isotropic downstream of the x-line with electrons heated in the perpendicular direction.La reconnexion magnétique est un mécanisme fondamental de conversion d'énergie dans le plasma. Il se déroule dans les régions minces de fort courant appelées couches de courants, et produit le chauffage et l accélération des particules. Dans un milieu turbulent, la reconnexion magnétique a été observée dans de petites structures qui se forment dans celui-ci, et on a postulé que cela contribue de façon importante la dissipation de l'énergie turbulente l'échelle cinétique. Pour ce travail, nous examinons les données des satellites Custer dans la magnétogaine de la Terre, en aval du choc quasi-parallèle. La détection des couches de courant d'échelle ionique a été réalisé par l'application de la méthode de la variance partielle des incréments (PVI) pour des satellites multiples. Les proprietées des couches de courant observées étaient différentes pour des valeurs de l'indice PVI élevées(PV I > 3) et bas (PV I 3) structures qui représentaient ~ 20% du total. Ces couches de courant ont une rotation du champ magnétique élevée (> 90o). Afin d'estimer le chauffage local survenant dans ces couches de courant, une estimation de la température des électrons a été obtenue à haute résolution temporelle (125ms) parles distributions d'électrons partielles mesurées par Cluster. Cela a permis pour la première fois d'étudier le chauffage d'électrons localisés dans les couches de courant d'échelle ionique. L'augmentation observée de la température des électrons estimée dans les couches de courant aux PVI élevées suggèrent qu'ils sont importants pour le chauffage local d'électrons et de dissipation d'énergie. Nous avons également examiné les mesures l'intérieur de la région de diffusion d'une couche de courant o la reconnexion magnétique est en cours. Les observations simultanées par des satellites multiples permettent aussi d'étudier les distributions d'électrons et l'activité des ondes à des distances différentes de la ligne x. Des différences significatives ont été observées dans les populations d'électrons comme ils ont été chauffés en passant par la couche de courant. En particulier, les électrons sont chauffés dans la direction parallèle au champ magnétique proximité de la ligne x, alors qu'aucune variation significative n'a été observée dans la direction perpendiculaire. Cependant,la distribution est plus isotrope en aval de la ligne x, chauffées par des électrons dans la direction perpendiculaire
Graph properties of graph associahedra
No full textInternational audienceA graph associahedron is a simple polytope whose face lattice encodes the nested structure of the connected subgraphs of a given graph. In this paper, we study certain graph properties of the -skeleta of graph associahedra, such as their diameter and their Hamiltonicity. Our results extend known results for the classical associahedra (path associahedra) and permutahedra (complete graph associahedra). We also discuss partial extensions to the family of nestohedra