Comparison of quasi-spherical surfaces – application to corneal biometry

International audienc

Le chien, la galette et le lauréat. Douzième récit du Yuhuaxiang (Fleurs du Paradis) de Shi Chengjin

International audiencePrésentation et traduction d'un conte en langue vulgaire de Shi Chengjin 石成金 (zi Tianji 天基) tiré de son recueil Yuhuaxiang 雨花香 (Fleurs du Paradis

San Francisco sous la plume de Bret Harte – The Overland Monthly, 1868-1871

National audienceA partir des éditoriaux rédigés par Bret Harte dans le magazine californien The Overland Monthly, cet article dresse un portrait de la ville de San Francisco en plein essor capitaliste au début des années 1870

A Collaborative Requirement Mining Framework to Support OEMs

12th International Conference, CDVE 2015, Mallorca, Spain, September 20-23, 2015. ProceedingsInternational audienceWith the fastidiously ever-increasing complexity of systems, the relentless, massive customisation of products and the mushrooming accumulation of legal documents (standards, policies and laws), we can observe a significant increase in requirements. We consider the tremendous volume of requirements as big data with which companies struggle to make strategic decisions early on. This paper proposes a collaborative requirement mining framework to enable the decision-makers of an Original Equipment Manufacturer (OEM) to gain insight and discover opportunities in a massive set of requirements so as to make early effective strategic decisions. The framework supports OEMs willing to uncover a subset of key requirements by distilling large unstructured and semi-structured specifications

The fate of early Mars' lost water: The role of serpentinization

International audienceThe fate of water which was present on early Mars remains enigmatic. We propose a simple model based on serpentinization, a hydrothermal alteration process which may produce magnetite and store water. Our model invokes serpentinization during about 500 to 800 Myr, while a dynamo is active, which may have continued after the formation of the crustal dichotomy. We show that the present magnetic field measured by MGS in the Southern hemisphere is consistent with a ~500 m thick Global Equivalent Layer of water trapped in serpentine. Serpentinization results in the release of H2. The released H atoms are lost to space through thermal escape, increasing the D/H ratio in water reservoirs exchanging with atmosphere. We show that the value of the D/H ratio in the present atmosphere (~5) is consistent with the serpentinization of a ~500 m thick water GEL. We reassess the role of non-thermal escape in removing water from the planet. By considering an updated solar wind-ionosphere interaction representation, we show that the contribution of oxygen escape to H isotopic fractionation is negligible. Our results suggest that significant amounts of water (up to a ~330-1030 m thick GEL) present at the surface during the Noachian, similar to the quantity inferred from the morphological analysis of valley networks, could be stored today in subsurface serpentine

Ultrasonic waves Reflected at Oblique Incidence by Porous Rigid Medium.

International audienceAn ultrasonic reflected wave at oblique incidence by porous medium with rigid frames is considered using equivalent fluid model. The viscous and thermal losses of the medium are described by two susceptibility kernels which depend on the viscous and thermal characteristic lengths. Analytical derivation of reflection coefficient is given in frequency domain. The simulated reflected wave is obtained at time domain by convolution between the reflected operator and the incident field. Experimental results for plastic foam samples of air-saturated porous media are given and compared with theoretical prediction

Transient detection and encoding using wavelet coefficient trees

International audienceMany signal processing problems call for accurate and efficient models for transient signals, and corresponding detection/estimation algorithms. This paper proposes a general setting for transient models, based upon dyadic trees of wavelet coefficients. A deterministic and a stochastic model are presented, and corresponding estimation algorithms are described. Numerical results are given in the framework of audio signal encoding.Un grand nombre deprobì emes de traitement du signal nécessitent des mod eles précis et efficaces de signaux transitoires, et des algorithmes de détection et estimation correspondants. On propose dans cet article un cadre général pour des mod eles de transitoires, basé sur des arbres dyadiques de coefficients d'ondelettes. Un mod ele déterministe et un mod ele stochastique sont présentés , et des algorithmes d'estimation correspondants sont décrits. Les résultats sont illustrés par des exemples numériques , dans un cadre de codage de signaux audi

Follow-up of high energy neutrinos detected by the ANTARES telescope

International audienceThe ANTARES telescope is well-suited to detect high energy neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky with a high duty cycle. Potential neutrino sources are gamma-ray bursts, core-collapse supernovae and flaring active galactic nuclei. To enhance the sensitivity of ANTARES to such sources, a detection method based on follow-up observations from the neutrino direction has been developed. This program, denoted as TAToO, includes a network of robotic optical telescopes (TAROT, Zadko and MASTER) and the Swift-XRT telescope, which are triggered when an 'interesting' neutrino is detected by ANTARES. A follow-up of special events, such as neutrino doublets in time/space coincidence or a single neutrino having a very high energy or in the specific direction of a local galaxy, significantly improves the perspective for the detection of transient sources. The analysis of early and long term follow-up observations to search for fast and slowly varying transient sources, respectively, has been performed and the results covering optical and X-ray data are presented in this contribution

Cannabinoid-induced actomyosin contractility shapes neuronal morphology and growth

International audienceEndocannabinoids are recently recognized regulators of brain development, but molecular effectors downstream of type-1 cannabinoid receptor (CB1R)-activation remain incompletely understood. We report atypical coupling of neuronal CB1Rs, after activation by endo-or exocannabinoids such as the marijuana component ∆ 9-tetrahydrocannabinol, to heterotrimeric G 12 /G 13 proteins that triggers rapid and reversible non-muscle myosin II (NM II) dependent contraction of the actomyosin cytoskeleton, through a Rho-GTPase and Rho-associated kinase (ROCK). This induces rapid neuronal remodeling, such as retraction of neurites and axonal growth cones, elevated neuronal rigidity, and reshaping of somatodendritic morphology. Chronic pharmacological inhibition of NM II prevents cannabinoid-induced reduction of dendritic development in vitro and leads, similarly to blockade of endocannabinoid action, to excessive growth of corticofugal axons into the sub-ventricular zone in vivo. Our results suggest that CB1R can rapidly transform the neuronal cytoskeleton through actomyosin contractility, resulting in cellular remodeling events ultimately able to affect the brain architecture and wiring

Le théorème des accroissements finis comme question curriculaire

International audienceBeyond the difficulty to give true practical motives to introduce a theorem, the didactic transposition of scholarly knowledge in a school setting often leads to freezing a technical tool into a theorem given under minimal assumptions. Probably whole categories of exercises have no other justification than establishing the necessity of introducing a theorem under minimal assumptions in a curriculum. The mean value theorem represents a paradigmatic situation, showing not only the expectations of the curriculum writers, but also part of the school unconscious that manifests itself in the very notion of rigor.Más allá de la dificultad para proponer verdaderas motivaciones prácticas para la introducción de un teorema, la transposición didáctica de un saber sabio en el ámbito escolar lleva a menudo a fijar una herramienta técnica en un teorema enunciado bajo hipótesis mínimas. Ciertas categorías de ejercicios probablemente no tienen más justificación que la de establecer la necesidad de introducir en el currículo un teorema bajo sus hipótesis mínimas. El teorema del valor medio constituye una situación paradigmática que permite observar no solo las expectativas de los autores del currículo sino también una parte del inconsciente escolar que se manifiesta en la noción de rigor.Outre la difficulté à proposer de réelles motivations pratiques pour l'introduction d’un théorème, la transposition didactique d'un savoir savant dans le cadre scolaire conduit souvent à figer un outil technique en théorème énoncé sous des hypothèses minimales. Des catégories entières d'exercices n'ont probablement pas d'autre raison d'être que de justifier la présence au programme d’un théorème sous ses hypothèses minimales. Le théorème des accroissements finis constitue une situation paradigmatique pour observer non seulement les attentes des rédacteurs d'un programme d'enseignement, mais également une partie de l’inconscient d’école qui se manifeste dans la notion même de rigueur