A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

SERENA:Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

International audienceThe ESA-JAXA BepiColombo mission to Mercury will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric particle dynamics at Mercury as well as their interactions with solar wind, solar radiation, and interplanetary dust. The particle instrument suite SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) is flying in space on-board the BepiColombo Mercury Planetary Orbiter (MPO) and is the only instrument for ion and neutral particle detection aboard the MPO. It comprises four independent sensors: ELENA for neutral particle flow detection, Strofio for neutral gas detection, PICAM for planetary ions observations, and MIPA, mostly for solar wind ion measurements. SERENA is managed by a System Control Unit located inside the ELENA box. In the present paper the scientific goals of this suite are described, and then the four units are detailed, as well as their major features and calibration results. Finally, the SERENA operational activities are shown during the orbital path around Mercury, with also some reference to the activities planned during the long cruise phase

Correction to: SERENA: Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

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Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Impact d'une formation médicale sur le sevrage des benzodiazépines et sur la prise en charge de l'insomnie chronique en soins primaires

Introduction : Il est nécessaire de former davantage les médecins généralistes sur la prise en charge des troubles du sommeil de leurs patients, ainsi que dans leurs compétences à proposer une alternative aux benzodiazépines. Une courte formation médicale interactive est-elle suffisante pour obtenir une diminution des consommations chroniques du patient insomniaque et améliorer les pratiques professionnelles ? Méthode : Deux études quantitatives concernant 23 médecins généralistes ambulatoires ont été menées sur la période de juin 2011 à mars 2012. - ETUDE SEVRAGE : Une étude d'intervention contrôlée (versus groupe témoin), concernant l'évaluation d'une tentative de sevrage des benzodiazépines à 6 mois de la formation. - EPP SOMMEIL : Une étude déclarative, rétrospective, observationnelle et comparative (versus médecins non formés) concernant l'évaluation des pratiques professionnelles dans l'insomnie avant / après formation. Résultats : - Etude sevrage : Elle concerne 90 patients dans le groupe intervention et 106 dans le groupe témoin, avec suivi à 6 mois. Le taux de réduction global des doses est de 31.3% (groupe intervention) versus 13.5% (p=0.02). Le pourcentage de sevrage total est de 28.9% versus 13.3% (p=0.007). - EPP sommeil : 7 médecins de chaque groupe y ont participé incluant 70 patients à T0 et à T6. L'évolution des pratiques des médecins formés est significative dans 4 critères d'évaluation sur 6. Or statistiquement comparée dans le temps avec le groupe témoin, cette évolution n'est pas significative. Une probable contamination du groupe témoin et de faibles effectifs en limitent l'interprétation. Conclusion : Il existe un réel impact d'une telle formation dans la faculté des médecins à conduire un sevrage des benzodiazépines, y compris dans une population présentant une consommation chronique dans l'indication trouble du sommeil .POITIERS-BU Médecine pharmacie (861942103) / SudocSudocFranceF

A Lagrangian intermittent model for turbulent lifted flame

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High pressure supercritical turbulent cryogenic injection and combustion : a single flow modelling proposal

International audienc

Hierarchical Watershed Segmentation Based On Gradient Image Simplification

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Contribution à la modélisation de la combustion non prémélangée turbulente dans les écoulements rapides

Le travail présenté dans ce mémoire est consacré à la combustion turbulente non-prémélangée dans des écoulements rapides, et éventuellement diphasiques. Pour ce type de conditions, il devient nécessaire, du point de vue de la modélisation, de tenir compte du couplage existant entre les effets de compressibilité, les processus de mélange turbulent et la cinétique chimique. Dans ces écoulements, la conversion de tout ou partie de l'énergie cinétique de l'écoulement sous forme d'enthalpie sensible va influencer le développement des réactions chimiques et peut contribuer notablement à la conversion des réactifs en produits de combustion ainsi qu'à la stabilisation des flammes. De plus, les échelles de temps caractéristiques du mélange turbulent et de la cinétique chimique sont susceptibles d'être du même ordre de grandeur et l' ypothèse de chimie infiniment rapide n'est pas toujours applicable. Dans cette étude, une approche basée sur l'évaluation de la PDF jointe de deux quantités scalaires est retenue : la première variable permet de quantifier la richesse locale du mélange, la seconde caractérise l'écart à l'état d'équilibre chimique. Une hypothèse de "chimie brusque" permet d'introduire une dépendance explicite entre ces deux variables pour s'en tenir à la seule détermination de la PDF de la variable de mélange. Cette approche est étendue au cas de la combustion supersonique en considérant de surcroît les variations d'enthalpie totale. Enfin, les fluctuations de composition induites par la vaporisation d'un des deux réactifs sont elles-aussi prises en compte. Le modèle complet est implanté dans un code de calcul Navier-Stokes tridimensionnel compressible et réactif. Dans le cadre de cette étude, la résolution est couplée à une méthode d'adaptation de maillage qui permet d'améliorer significativement la représentation des zones de mélange et des fortes discontinuités. L'approche proposée est ensuite validée en s'appuyant sur différentes géométries: jets co-courants supersoniques H2-air vicié, jets fortement sous-détendus, chambre de combustion de type Scramjet. Enfin, le modèle est aussi employé pour effectuer un calcul de la configuration Mascotte de l'Onera dans un cas sous-critique. Les simulations numériques correspondantes conduisent à des résultats encourageants et ouvrent de nombreuses perspectives aussi bien quant à l'utilisation du modèle le cadre d'approches U-RANS ou LES que vis-à-vis de son extension à des conditions de combustion extrêmes (super-critiques).This work is dedicated to the study of non-premixed turbulent combustion in high-speed and two-phase flows. From a modeling point of view, it is of primary importance to take into consideration the coupling that exists for those con gurations between the effects of compressibility, turbulent mixing, and chemistry. In supersonic reactive flows, the conversion of a portion of kinetic energy into heat or enthalpy is to influence significantly the early developments of chemical reactions and thus, lead to an increase of the chemical conversion of reactants into products of reaction, and contribute to the stabilisation process of the flame. Moreover, the value of the time scale representative of the turbulent mixing and the value of the chemical time scale are expected to be comparable, so that the fast chemistry assumption can be questionned. In this study, an approach based on the estimation of the joint PDF of two scalars, the first quantity describing the local composition of the mixture, and the second characterizing the progress of the reaction, is retained. The model relies on the sudden chemistry assumption, thus permitting a strong but clearly stated functional dependence between the two scalars introduced. As a result, the joint PDF of the two scalars can be simply expressed from the knowledge of the marginal mixture fraction PDF. This approach is extended to the description of supersonic combustion by considering the variations of total enthalpy. Finally, the fluctuations of composition induced by the evaporation of one of the two reactants are also taken into account. The full model is implemented into Computational Fluid Dynamics code, solving the three-dimensional compressible and reactive Navier-Stokes equations. In this work, the representation of the mixing layers and discontinuities is improved thanks to the use of a mesh adaptation strategy, coupled to the CFD code. The numerical and modeling approach is then validated against various configurations : coflowing H2-vitiated air supersonic jets, highly underexpanded jets, and a Scramjet-like combustion chamber. Finally, the modeling framework is also extended to the simulation of the Mascotte configuration (ONERA) with sub-critical liquid oxygen. The results obtained on those configurations are in satisfactory agreement with both underlying physics and experimental data when available, and the numerical code and modeling strategy are shown to be viable tools for further developments and investigations within U-RANS or LES approaches, and for its extension to more extreme conditions (super-critical oxygen).POITIERS-BU Sciences (861942102) / SudocSudocFranceF