[Immunopathogenesis of inflammatory bowel disease.]

International audienceInflammatory bowel diseases (IBD) are idiopathic, chronic and relapsing inflammatory conditions of the gastrointestinal tract. New insights into the pathogenesis of IBD have been provided by three lines of research: (1) studying susceptibility genes involved in the detection of bacterial components and in the regulation of the host immune response, (2) highlighting the disruption of tolerance towards the commensal microbiota and (3) unravelling the critical role of environmental factors such as sanitation and hygiene. This review presents current etiological hypothesis of IBD which argue that pathogenic intestinal bacteria and/or infectious agents initiate and perpetuate the inflammation of the gut in an individual with genetic vulnerability leading to impaired epithelial barrier function and abnormal mucosal immune responses

Recherches sur les cultes orientaux à Athènes, du Ve siècle avant J.-C. au IVe siècle après J.-C.

The reputation of "philoxenia" enjoyed by Athens since Antiquity raises the question of the real capacity of welcome and integration of the city towards foreigners, their culture and their religion. It leads to study the differente ways of introducing and receiving a set of worship, gathered under the generic and convenient word - although today much discussed - of "Oriental cuits" : in this study, the "Oriental cuits" are defined by their geographical meaning, as all the religions coming from the Eastern Mediterranean (Egypt, Anatolia, Syria and Phoenicia), including Christianity and Judaism. Leaning on an extensive and varied documentation - and especially a large epigraphie corpus - this paper aims to point out the means of spreading of these cuits and the circumstances in which they settle in the city of Albens. A chronological approach emphasizes the existence of local dynamics, which explains the unequal popularity experienced by the different Oriental cults with Athenians : while sorne of them are criticized and rejected, the cults of Cybele and Isis achieved a great success in Attica. Such a success requires necessarily changes and modifications to allow these new cults to adapt themselves to a different audience and to a new framework of reception : after their arrival, the new cults interact with the local religions background and are affected - to varying degrees - by a phenomenon of hellenization, facilitated by the process of interpretario. Thus, in the city, the Oriental deities have some universal features - that are found throughout the Mediterranean world in the imperial period - , but the contacts and the interactions with the local gods - especially with Demeter, the great Eleusinian goddess - have also led to the emergence of local characteristics, specifie to the Athenian context.La réputation de philoxénie dont jouit Athènes dès l'Antiquité pose la question de la réelle capacité d'accueil et d'intégration de la cité à l'égard des étrangers, de leur culture et de leur religion. Elle conduit à étudier les modalités d'introduction et de réception d'un ensemble de cultes, réunis sous le qualificatif générique et commode - bien qu'aujourd'hui très discuté- de «cultes orientaux» : dans cette étude, les "cultes orientaux" sont définis au sens géographique du terme, comme l'ensemble des cultes provenant de l'Est du bassin méditerranéen (Egypte, Anatolie, Syrie et Phénicie), y compris le christianisme et le judaïsme. S'appuyant sur une documentation abondante et variée - et notamment sur un corpus épigraphique conséquent - , ce travail vise à mettre en évidence les vecteurs de diffusion de ces cultes et les circonstances dans lesquelles ils s'implantent dans la cité athénienne. Une approche chronologique souligne l'existence de dynamiques locales, qui expliquent l'inégale popularité rencontrée par les cultes orientaux auprès des Athéniens : alors que certains sont critiqués et rejetés, les cultes de Cybèle et Isis remportent un grand succès en Attique. Une telle réussite suppose nécessairement des transformations, des modifications, pour permettre aux cultes de s'adapter à un public différent, à un nouveau cadre de réception: après leur arrivée, les nouveaux cultes entrent en interaction avec le milieu religieux local et subissent- à des degrés variables - un phénomène d'hellénisation, facilité par le processus de l' interprétation. Dans la cité, les divinités orientales présentent ainsi certaines caractéristiques universelles, que l'on retrouve un peu partout dans le monde méditerranéen à l'époque impériale, mais les contacts et les interactions avec les divinités locales- et notamment avec Déméter, la grande déesse d'Eleusis- ont aussi conduit à l'émergence de spécificités locales, particulière au contexte athénien

An exactly solvable model of the BCS-BEC crossover

We discuss an integrable model of interacting Fermions in one dimension, that allows an exact description of the crossover from a BCS- to a Bose-like superfluid. This model bridges the Gaudin-Yang model of attractive spin 1/2 Fermions to the Lieb-Liniger model of repulsive Bosons. Using a geometric resonance in the one-dimensional scattering length, the inverse coupling constant varies from minus infinity to plus infinity while the system evolves from a BCS-like state through a Tonks gas to a weakly interacting Bose gas of dimers. We study the ground state energy, the elementary density and spin excitations, and the correlation functions. An experimental realization with cold atoms of such a one-dimensional BCS-BEC crossover is proposed.Comment: corrected typos, minor modifications, submitted versio

Superheating fields of superconductors: Asymptotic analysis and numerical results

The superheated Meissner state in type-I superconductors is studied both analytically and numerically within the framework of Ginzburg-Landau theory. Using the method of matched asymptotic expansions we have developed a systematic expansion for the solutions of the Ginzburg-Landau equations in the limit of small $\kappa$, and have determined the maximum superheating field $H_{\rm sh}$ for the existence of the metastable, superheated Meissner state as an expansion in powers of $\kappa^{1/2}$. Our numerical solutions of these equations agree quite well with the asymptotic solutions for $\kappa<0.5$. The same asymptotic methods are also used to study the stability of the solutions, as well as a modified version of the Ginzburg-Landau equations which incorporates nonlocal electrodynamics. Finally, we compare our numerical results for the superheating field for large-$\kappa$ against recent asymptotic results for large-$\kappa$, and again find a close agreement. Our results demonstrate the efficacy of the method of matched asymptotic expansions for dealing with problems in inhomogeneous superconductivity involving boundary layers.Comment: 14 pages, 8 uuencoded figures, Revtex 3.

Dynamics of vortex penetration, jumpwise instabilities and nonlinear surface resistance of type-II superconductors in strong rf fields

We consider nonlinear dynamics of a single vortex in a superconductor in a strong rf magnetic field $B_0\sin\omega t$. Using the London theory, we calculate the dissipated power $Q(B_0,\omega)$, and the transient time scales of vortex motion for the linear Bardeen-Stephen viscous drag force, which results in unphysically high vortex velocities during vortex penetration through the oscillating surface barrier. It is shown that penetration of a single vortex through the ac surface barrier always involves penetration of an antivortex and the subsequent annihilation of the vortex antivortex pairs. Using the nonlinear Larkin-Ovchinnikov (LO) viscous drag force at higher vortex velocities $v(t)$ results in a jump-wise vortex penetration through the surface barrier and a significant increase of the dissipated power. We calculate the effect of dissipation on nonlinear vortex viscosity $\eta(v)$ and the rf vortex dynamics and show that it can also result in the LO-type behavior, instabilities, and thermal localization of penetrating vortex channels. We propose a thermal feedback model of $\eta(v)$, which not only results in the LO dependence of $\eta(v)$ for a steady-state motion, but also takes into account retardation of temperature field around rapidly accelerating vortex, and a long-range interaction with the surface. We also address the effect of pinning on the nonlinear rf vortex dynamics and the effect of trapped magnetic flux on the surface resistance $R_s$ calculated as a function or rf frequency and field. It is shown that trapped flux can result in a temperature-independent residual resistance $R_i$ at low $T$, and a hysteretic low-field dependence of $R_i(B_0)$, which can {\it decrease} as $B_0$ is increased, reaching a minimum at $B_0$ much smaller than the thermodynamic critical field $B_c$.Comment: 18 figure

An Iterative Algorithm for Forward-Parameterized Skill Discovery

International audienceWe introduce COCOTTE (COnstrained Complexity Optimization Through iTerative merging of Experts), an iterative algorithm for discovering discrete, meaningful parameterized skills and learning explicit models of them from a set of behaviour examples. We show that forward-parameterized skills can be seen as smooth components of a locally smooth function and, framing the problem as the constrained minimization of a complexity measure, we propose an iterative algorithm to discover them. This algorithm fits well in the developmental robotics framework, as it does not require any external definition of a parameterized task, but discovers skills parameterized by the action from data. An application of our method to a simulated setup featuring a robotic arm interacting with an object is shown

Neuropathological and Reelin Deficiencies in the Hippocampal Formation of Rats Exposed to MAM; Differences and Similarities with Schizophrenia

Adult rats exposed to methylazoxymethanol (MAM) at embryonic day 17 (E17) consistently display behavioral characteristics similar to that observed in patients with schizophrenia and replicate neuropathological findings from the prefrontal cortex of psychotic individuals. However, a systematic neuropathological analysis of the hippocampal formation and the thalamus in these rats is lacking. It is also unclear if reelin, a protein consistently associated with schizophrenia and potentially involved in the mechanism of action of MAM, participates in the neuropathological effects of this compound. Therefore, a thorough assessment including cytoarchitectural and neuromorphometric measurements of eleven brain regions was conducted. Numbers of reelin positive cells and reelin expression and methylation levels were also studied.Compared to untreated rats, MAM-exposed animals showed a reduction in the volume of entorhinal cortex, hippocampus and mediodorsal thalamus associated with decreased neuronal soma. The entorhinal cortex also showed laminar disorganization and neuronal clusters. Reelin methylation in the hippocampus was decreased whereas reelin positive neurons and reelin expression were unchanged.Our results indicate that E17-MAM exposure reproduces findings from the hippocampal formation and the mediodorsal thalamus of patients with schizophrenia while providing little support for reelin's involvement. Moreover, these results strongly suggest MAM-treated animals have a diminished neuropil, which likely arises from abnormal neurite formation; this supports a recently proposed pathophysiological hypothesis for schizophrenia

Statistical comparison of algorithm performance through instance selection

Algorithms and the Foundations of Software technolog

Beam tests of the trigger and digital processing electronics for the electromagnetic calorimeter of the CMS experiment

A prototype of the trigger and digital processing electronics for the electromagnetic calorimeter of the CMS experiment, coupled to a prototype of the PbWO4 crystal calorimeter, was tested during summer 96 in the H4 beamline at the CERN SPS. A very successful operation was achieved for this system, which runs in synchronous and pipelined mode at the LHC clock frequency, and performs the basic trigger and data acquisition functions needed in the CMS electromagnetic calorimeter. The performance of the trigger front-end electronics is well within the established requirements: a highly efficient bunch crossing identification ( &gt; 99.9%), a good trigger energy resolution ( s/E ~9%/sq( E)+2%) and a highly efficient electron cluster shape identification ( ~99%) have been achieved. The FERMI digitizing system based on a dynamic analog compressor and a sampling ADC showed a very good perform ance, in particular the energy resolution for 150 GeV electrons was 0.54%, equal to the resolution obtained with a conventional charge integration ADC system