37 research outputs found
Recent advances in collisional effects on spectra of molecular gases and their practical consequences
International audienceWe review progress, since publication of the book "Collisional effects on molecular spectra Laboratory experiments and models, consequences for applications" (Elsevier, Amsterdam, 2008), on measuring, modeling and predicting the influence of pressure (ie of intermolecular collisions) on the spectra of gas molecules. We first introduce recently developed experimental techniques of high accuracy and sensitivity. We then complement the aforementioned book by presenting the theoretical approaches, results and data proposed (mostly) in the last decade on the topics of isolated line shapes, line-broadening and-shifting, line-mixing, the far wings and associated continua, and collision-induced absorption. Examples of recently demonstrated consequences of the progress in the description of spectral shapes for some practical applications (metrology, probing of gas media, climate predictions) are then given. Remaining issues and directions for future research are finally discussed
Migration-driven diversity of super-Earth compositions
A leading model for the origin of super-Earths proposes that planetary embryos migrate inward and pile up on close-in orbits. As large embryos are thought to preferentially form beyond the snow line, this naively predicts that most super-Earths should be very water-rich. Here we show that the shortest-period planets formed in the migration model are often purely rocky. The inward migration of icy embryos through the terrestrial zone accelerates the growth of rocky planets via resonant shepherding. We illustrate this process with a simulation that provided a match to the Kepler-36 system of two planets on close orbits with very different densities. In the simulation, two super-Earths formed in a Kepler-36-like configuration; the inner planet was pure rock while the outer one was ice-rich. We conclude from a suite of simulations that the feeding zones of close-in super-Earths are likely to be broad and disconnected from their final orbital radii
ECOPHYTO R&D : Vers des systÚmes de culture économes en produits phytosanitaires. Volet 2 TOME IX : Conception d'un réseau d'acquisition de références et d'un réseau d'information
International audienceLes pouvoirs publics souhaitent favoriser lâadoption de systĂšmes de culture Ă©conomes en pesticides, en mettant en place un rĂ©seau dâacquisition de rĂ©fĂ©rences expĂ©rimentales et de dĂ©monstration, associĂ© Ă un systĂšme dâinformation. Pour rĂ©pondre Ă cette demande, le groupe "RĂ©seau" a fait un Ă©tat des lieux, proposĂ© une configuration, et Ă©valuĂ© les moyens nĂ©cessaires. Lâinventaire des dispositifs expĂ©rimentaux Ă©tudiant des systĂšmes de culture a recensĂ© 87 dispositifs en grande culture, 33 en arboriculture fruitiĂšre, 9 en vigne et 36 en cultures lĂ©gumiĂšres. Les donnĂ©es collectĂ©es sâavĂšrent dispersĂ©es et disparates, difficiles Ă mobiliser et Ă valoriser faute dâoutils compatibles entre eux ou communs pour gĂ©rer ces donnĂ©es, et globalement insuffisantes. Le dispositif proposĂ© comprend 2 fonctions complĂ©mentaires et indissociables : - un rĂ©seau expĂ©rimental pour lâacquisition de rĂ©fĂ©rences, avec la construction et lâĂ©valuation de systĂšmes de culture Ă©conomes en pesticides via un rĂ©seau dâexpĂ©rimentation-dĂ©monstration comprenant des dispositifs dâapprentissage, de mise en oeuvre en conditions commerciales et de dĂ©monstration, avec 3 modules (EXPE, FERME et DECI) ; - un systĂšme dâinformation pour la gestion des connaissances, avec la mise Ă disposition de ressources pour lâactivitĂ© des conseillers et la valorisation de lâactivitĂ© de recherche, dâexpĂ©rimentation et de production de rĂ©fĂ©rences, avec 2 modules (BASE et GECO). Lâorganisation de lâensemble repose sur un pilotage du dispositif au sein dâun mĂȘme groupement et un conventionnement avec les partenaires rĂ©gionaux ou nationaux. En rĂ©gime de croisiĂšre, lâopĂ©ration pourrait comprendre 50 sites expĂ©rimentaux (EXPE), 800 fermes pilotes (FERME), 30 projets de recherche en cours (DECI) sur la base de 10 nouveaux projets dâune durĂ©e de 3 ans chaque annĂ©e, plus la gestion de la base de donnĂ©es et de la plateforme informatique associĂ©e (BASE), et la base de gestion des connaissances (GECO). Sur cette base de calcul, il mobiliserait lâĂ©quivalent de 130 ETP au total