The invariant joint distribution of a stationary random field and its derivatives: Euler characteristic and critical point counts in 2 and 3D

The full moments expansion of the joint probability distribution of an isotropic random field, its gradient and invariants of the Hessian is presented in 2 and 3D. It allows for explicit expression for the Euler characteristic in ND and computation of extrema counts as functions of the excursion set threshold and the spectral parameter, as illustrated on model examples.Comment: 4 pages, 2 figures. Corrected expansion coefficients for orders n>=5. Relation between Gram-Charlier and Edgeworth expansions is clarified

Le tourisme dans les outre-mers de l'océan Pacifique

Les outre-mers du Pacifique n'ont que peu bénéficié du spectaculaire essor du tourisme dans cette zone, lié au développement économique de l'Asie orientale. Bien que l'augmentation du flux touristique soit lente dans les TOM, on assiste à une réorganisation spatiale du tourisme, tout particulièrement en Polynésie française

La diffusion du tourisme dans l'archipel comorien

Des considérations politiques ont largement influencé la diffusion du tourisme dans l'archipel comorien. Sa balkanisation explique que deux îles sont concernées par le tourisme, en dépit d'un flux réduit

Non Gaussian extrema counts for CMB maps

In the context of the geometrical analysis of weakly non Gaussian CMB maps, the 2D differential extrema counts as functions of the excursion set threshold is derived from the full moments expansion of the joint probability distribution of an isotropic random field, its gradient and invariants of the Hessian. Analytic expressions for these counts are given to second order in the non Gaussian correction, while a Monte Carlo method to compute them to arbitrary order is presented. Matching count statistics to these estimators is illustrated on fiducial non-Gaussian "Planck" data.Comment: 4 pages, 1 figur

Etudes de sensibilité avec COMETH

National audienceRESUME. La place importante des outils de calcul dans l'évaluation de la performance éner-gétique d'un bâtiment associé aux exigences toujours plus importantes sur les performances des bâtiments nécessite aujourd'hui de porter un regard critique sur leur abilité. Dans le cadre du projet ANR FIABILITE (HABISOL 2010), COMETH, (Coeur de calcul pour la Modélisation Énergétique et le confort Thermique) a été utilisé pour eectuer des études de sensibilité à di-vers paramètres. Cette démarche vise plusieurs objectifs. Tout d'abord, à valider notre capacité à fournir à la lière bâtiment des outils d'analyse de sensibilité rapide, simple d'utilisation et dont les résultats sont rapidement exploitables. Ensuite, sonder des paramètres jusqu'ici laissés de côté dans les approches thermiques horaires dynamiques dites "simples" (en référence au vocabulaire de la norme ISO 13790). MOTS-CLEFS. COMETH, étude de sensibilisé, SE

Un coronographe interf\'erentiel achromatique coaxial

On-axis achromatic interfero-coronagraph. We present a new type of stellar interfero-coronagraph, the "CIAXE", which is a variant of the "AIC", the Achromatic Interfero-Coronagraph [3,4]. The CIAXE is characterized by a very simple, compact and fully coaxial optical combination. Indeed, contrarily to the classical AIC which has a Michelson interferometer structure, the CIAXE delivers its output beam on the same axis as the input beam. This will ease its insertion in the focal instrumentation of existing telescopes or next generation ones. Such a device could be a step forward in the field of instrumental search for exoplanets. ----- Dans le but deparvenir \`a l'imagerie \`a haute dynamique d'objets comme les exoplan\`etes, nous pr\'esentons ici un nouveau concept de coronographe stellaire interf\'erentiel, le "CIAXE". Il est d\'eriv\'e du "CIA", le Coronographe Interf\'erentiel Achromatique. Le CIAXE se distingue de son pr\'ed\'ecesseur par une combinaison optique originale, simplifi\'ee, tr\`es compacte et totalement coaxiale. En effet, \`a la diff\'erence du CIA classique qui est d\'eriv\'e de l'interf\'erom\`etre de Michelson, le CIAXE d\'elivre son faisceau de sortie sur le m\^eme axe que le faisceau d'entr\'ee, ce qui facilitera grandement son insertion au sein de l'instrumentation focale d'un t\'elescope. Un tel dispositif pourrait constituer une avanc\'ee en mati\`ere d'instrumentation focale pour la recherche d'exoplan\`etes

Impact of tapping and soil water status on fine root dynamics in a rubber tree plantation in Thailand

Fine roots (FR) play a major role in the water and nutrient uptake of plants and contribute significantly to the carbon and nutrient cycles of ecosystems through their annual production and turnover. FR growth dynamics were studied to understand the endogenous and exogenous factors driving these processes in a 14-year-old plantation of rubber trees located in easternThailand. FR dynamicswere observed using field rhizotrons from October 2007 to October 2009.This period covered two complete dry seasons (November to March) and two complete rainy seasons (April to October), allowing us to study the effect of rainfall seasonality on FR dynamics. Rainfall and its distribution during the two successive years showed strong differences with 1500 and 950 mm in 2008 and 2009, respectively. FR production (FRP) completely stopped during the dry seasons and resumed quickly after the first rains. During the rainy seasons, FRP and the daily root elongation rate (RER)were highly variable and exhibited strong annual variations with a total FRP of 139.8 and 40.4mm?2 and an average RER of 0.16 and 0.12 cm day?1 in 2008 and 2009, respectively. The significant positive correlations found between FRP, RER, the appearance of new roots, and rainfall at monthly intervals revealed the impact of rainfall seasonality on FR dynamics. However, the rainfall patterns failed to explain the weekly variations of FR dynamics observed particularly during the rainy seasons. At this time step, FRP, RER, and the appearance of new FR were negatively correlated to the average soil matric potential measured at a depth of between 30 and 60 cm. In addition, our study revealed a significant negative correlation between FR dynamics and the monthly production of dry rubber. Consequently, latex harvesting might disturb carbon dynamics in the whole tree, far beyond the trunk where the tapping was performed. These results exhibit the impact of climatic conditions and tapping system in the carbon budget of rubber plantations. (Résumé d'auteur

Noninvasive mechanical ventilation in high-risk pulmonary infections: a clinical review

The aim of this article was to review the role of noninvasive ventilation (NIV) in acute pulmonary infectious diseases, such as severe acute respiratory syndrome (SARS), H1N1 and tuberculosis, and to assess the risk of disease transmission with the use of NIV from patients to healthcare workers. We performed a clinical review by searching Medline and EMBASE. These databases were searched for articles on "clinical trials" and "randomised controlled trials". The keywords selected were non-invasive ventilation pulmonary infections, influenza-A (H1N1), SARS and tuberculosis. These terms were cross-referenced with the following keywords: health care workers, airborne infections, complications, intensive care unit and pandemic. The members of the International NIV Network examined the major results regarding NIV applications and SARS, H1N1 and tuberculosis. Cross-referencing mechanical ventilation with SARS yielded 76 studies, of which 10 studies involved the use of NIV and five were ultimately selected for inclusion in this review. Cross-referencing with H1N1 yielded 275 studies, of which 27 involved NIV. Of these, 22 were selected for review. Cross-referencing with tuberculosis yielded 285 studies, of which 15 involved NIV and from these seven were selected. In total 34 studies were selected for this review. NIV, when applied early in selected patients with SARS, H1N1 and acute pulmonary tuberculosis infections, can reverse respiratory failure. There are only a few reports of infectious disease transmission among healthcare workers

Review and classification of vision-based localisation techniques in unknown environments

International audienceThis study presents a review of the state-of-the-art and a novel classification of current vision-based localisation techniques in unknown environments. Indeed, because of progresses made in computer vision, it is now possible to consider vision-based systems as promising navigation means that can complement traditional navigation sensors like global navigation satellite systems (GNSSs) and inertial navigation systems. This study aims to review techniques employing a camera as a localisation sensor, provide a classification of techniques and introduce schemes that exploit the use of video information within a multi-sensor system. In fact, a general model is needed to better compare existing techniques in order to decide which approach is appropriate and which are the innovation axes. In addition, existing classifications only consider techniques based on vision as a standalone tool and do not consider video as a sensor among others. The focus is addressed to scenarios where no a priori knowledge of the environment is provided. In fact, these scenarios are the most challenging since the system has to cope with objects as they appear in the scene without any prior information about their expected position