Discovery of a Visual T-Dwarf Triple System and Binarity at the L/T Transition

We present new high contrast imaging of 8 L/T transition brown dwarfs using the NIRC2 camera on the Keck II telescope. One of our targets, the T3.5 dwarf 2MASS J08381155 + 1511155, was resolved into a hierarchal triple with projected separations of 2.5+/-0.5 AU and 27+/-5 AU for the BC and A(BC) components respectively. Resolved OSIRIS spectroscopy of the A(BC) components confirm that all system members are T dwarfs. The system therefore constitutes the first triple T-dwarf system ever reported. Using resolved photometry to model the integrated-light spectrum, we infer spectral types of T3, T3, and T4.5 for the A, B, and C components respectively. The uniformly brighter primary has a bluer J-Ks color than the next faintest component, which may reflect a sensitive dependence of the L/T transition temperature on gravity, or alternatively divergent cloud properties amongst components. Relying on empirical trends and evolutionary models we infer a total system mass of 0.034-0.104 Msun for the BC components at ages of 0.3-3 Gyr, which would imply a period of 12-21 yr assuming the system semi-major axis to be similar to its projection. We also infer differences in effective temperatures and surface gravities between components of no more than ~150 K and ~0.1 dex. Given the similar physical properties of the components, the 2M0838+15 system provides a controlled sample for constraining the relative roles of effective temperature, surface gravity, and dust clouds in the poorly understood L/T transition regime. Combining our imaging survey results with previous work we find an observed binary fraction of 4/18 or 22_{-8}^{+10}% for unresolved spectral types of L9-T4 at separations >~0.1 arcsec. This translates into a volume-corrected frequency of 13^{-6}_{+7}%, which is similar to values of ~9-12% reported outside the transition. (ABRIDGED)Comment: Accepted for publication in the Astrophysical Journal. 23 pages, 12 figure

Gossamer Technology to Deorbit LEO Non-Propulsion Fitted Satellite

Since 2004, CNES has decided to apply the end of life Code of Conduct rules to debris mitigation. Originally drawn up by the main European space agencies, it contains basic rules to be applied in space in order to limit the increase of orbital debris. In low Earth orbit, the rule is to limit in-orbit lifetime to 25 years after the end of the operational mission, or else to transfer to a graveyard orbit above 2000 km. In order to follow these instructions, a task force was set up in 2005 to find the best way to implement them on MICROSCOPE and CNES microsatellite family (MYRIADE). This 200-kg spacecraft should be launched in 2014 on a 790-km high circular orbit. Without targeted action, its natural re-entry would occur in 67 years. Two strategies to reduce this time period were compared: propulsive maneuvers at the end of the mission or the deployment of large surfaces to increase significantly the ballistic coefficient. At the end of the trade off, it was recommended: .. For the non-propulsive system fitted satellites, to use passive aerobraking by deployment of added surface, .. For satellites having propulsive subsystem in baseline for mission purposes, to keep sufficient propellant and implement specific maneuvers. The poster gives an overview of the process that led to the development of a deployable aerobraking wing using a lightweight aluminized Kapton membrane and an inflatable aluminum laminate boom. The main requirements; The trade off among various aerobraking solutions; The development plan. This technology presents a very attractive potential and it could be a first step in using of inflatable technology on spaces vehicles, before to deal with others more exigent applications

The diet of young eaters: a specific requirement requiring a reorganisation of family eating habits

International audienceThe diet of young eaters: a specific requirement requiring a reorganisation of family eating habitsL’alimentation des jeunes mangeurs : un besoin spécifique entrainant une réorganisation alimentaire familialeWe decided to take a look at what children eat by focusing on some analyses and results from a research programme on the diet of very young eaters, i.e. children aged between 0 and 3 (Dupuy and Rochedy, 2015). By analysing the underside of domestic and parental production in respect of the diet of small children, the report will focus on the supply journey, storage methods, culinary techniques, table manners and post-meal practices, describing them in terms of different life stages and also in respect of the development and socialisation of children. From a sociological point of view, how can we analyse the parental practices related to the act of feeding alongside those related to the construction of the list, or even the register, of what young children eat as a result of diversification? The various aspects of the work of parents have been investigated (Vandelac et al., 1985): the material work (shopping, preparing food and feeding the child/children but also the rest of the family, etc.), the cognitive work (thinking about what to eat and how to prepare it and anticipating the shopping that needs to be done, etc.) and the sentimental and relational work (family cohesion, being together, conversations/discussions around the child's diet, pleasure, conviviality and the child's well-being, etc.). It then becomes possible to question the evidence of this social fact: studying the work of parents in respect of the diet of young eaters in order to understand the changes, the disparities and the inequalities as well as the construction of the dietary practices of young eaters and the impact of parental work on their socialisation. This line of questioning, which is situated at the crossroads of the sociology of food, childhood, the family, health and gender relations, demands that particular attention be given to the juxtaposition and the combination of several dimensions. Firstly, the social construction of childhood (and early childhood) with the current place of the child and the small child, of children and small children, of childhood and early childhood, in the family, in culture and, more widely, the society under examination, which creates understanding of the socialisation, and particularly the multiple facets (horizontal, vertical and inverse) of food socialisation and the underlying inter/intra-generational relationships. Furthermore, the life stages and diet of the child are taken into account in the process of constructing the list of food (construction of likes and dislikes, rejections, preferences, neophobia, pleasure and emotion) alongside the prevalent childcare norms today. Finally, the issue of domestic and parental work (mental and physical tasks and the division and inequality of work within the family) and the "care" aspect, i.e. "thinking about others", which includes tangible and intangible practices, such as "emotional" components, provide an insight into the complexity of this task.Several points concerning the study are worthy of particular attention. The first relates to the fact that it takes into account a change in the child's diet from birth with milk given to begin with (dietary diversification with the first purée and then textured food with the introduction of lumps) until the child is integrated into family mealtimes, both physically and symbolically, by being served the same food as the rest of the family. These changes require ongoing readjustments in the feeding environment. Furthermore, this study takes a look at the practices and representations of the young child's diet from the point of view of the feeding environment while also considering what the child does with what he receives. Next, transitory ritualisation processes will be considered in order to reflect on the issue of these small rites that enable the child's socialisation and to verbalise the unspoken organisational aspects of the feeding environment in terms of certain cognitive shortcuts that are far from insignificant in daily life, comprising a vital process for parental organisation and, more broadly, for the feeding environment. The "transitory" dimension made it possible to put change and the dynamics of child and adult adaptation at the centre of the ritualisation of daily life as a result of the swings and transitions at work during food socialisation leading the child towards a non-specific diet. Thus, by analysing the diet of young children in this way, it was possible to study the various mental and physical pressures present in the feeding environment and the disparities at work in the threefold work of acquisition-transformation, relationship and love involved in the feeding role. Here again, the plurality and the complexity observed made it possible to re-question the division of domestic and parental tasks in respect of food during early childhood both in practice and in terms of values. Finally, implicitly throughout this study, we looked at the effects of the various educational influences on the processes of food socialisation in the child. The more a person is involved in the feeding role, the more that person has an influence on the relationship between food and the child's health, pleasure, well-being, self-fulfilment and development (Dupuy, 2013, 2014). Consequently, the socialisation processes experienced with the child are complicated, even more so given the concerns that weigh heavily on early childhood, which are currently centred on the importance of feeding children tasty healthy food in the first 1000 days of their lives. Nutritional needs, dietary needs and emotional needs are combined and are translated into, among other things, a sense of catching up in the feeding methods used or by parental guilt and also by a "stencil effect" (Fischler, 1990) in terms of both the list of foods offered to the child and the way in which the child is fed depending on the circumstances, the place, the time, the effect produced, etc. These elements can influence the socialisation processes at work in the child, i.e. what the child receives, how he experiences it and relates to it emotionally and, more importantly, what he takes away from it. Consequently, in the first part, we will set out the context and the challenges of children's diets in order to set the stage for questions involving the concerns surrounding the relationships between diet and health and diet and transmission for early childhood as a result of the importance placed on the first 1000 days in the life of a child. This will provide an opportunity to put these notions back in the centre of individual, collective and social dynamics. The second part will deal with the unequal distribution of the feeding work in respect of the young child. A third part will look at the empirical data of this study, and will be broken down into discussions on the methodology employed and on the study populations in the two geographical areas of France: Toulouse, Paris and their respective suburbs. Finally, the fourth and fifth parts will revisit two particular results from our research. We will discuss the organisational logic and the processes of food socialisation in order to gain an understanding of the evolution of the dietary act by moving away from the specific in favour of the general. We will then suggest a description and an analysis of the complex and unequal feeding work undertaken by parents. Bibliography: Dupuy A., 2013, Plaisirs alimentaires, Socialisation des enfants et des adolescents, Rennes, Presses Universitaires de Rennes.Dupuy A., 2014, « Regard(s) « sur » et « par » l’alimentation pour renverser et comprendre comment sont renversés les rapports de générations : l’exemple de la socialisation alimentaire inversée », Enfances Familles Générations, p. 79-108.Dupuy A et Rochedy A., 2015, L’alimentation des O-3 ans.Compréhension des processus de socialisations alimentaires des enfants entre 0 et 3 ans et étude des logiques de co-socialisation et de co-éducation de l’entourage nourricier, Rapport de Recherche CNRS – Blédina. Fischler C., 1990, L’homnivore, Paris, Odile Jacob.Vandelac L., Bélisle D., Gauthier A. et Pinard Y., 1985, Du travail et de l’amour, les dessous de la production domestique, Québec, Saint-Martin

Effets de la guerre civile au centre-Mozambique et évaluation d'une intervention de la Croix Rouge

Afin de mesurer l'évolution de la mortalité avant, pendant et après la guerre civile, une enquête a été conduite dans le district de Maringué, au Mozambique, en octobre 1994. L'enquête a porté sur les histoires des maternités de 1503 femmes de 15 à 60 ans. Les résultats de l'analyse révèlent une évolution complexe de la mortalité des enfants. Au cours de la fin de la période coloniale, la mortalité des moins de 5 ans baisse de 373 pour mille (1955-1959) à 270 pour mille (1970-1974). Puis elle passe par une période de stagnation entre 1975 et 1979. A partir de 1980, début de la guerre civile, la mortalité augmente rapidement pour atteindre un pic de 473 pour mille en 1986, à un niveau près du double de l'étiage des annnées 1965-1969. Puis la mortalité baisse à nouveau pour atteindre un plateau en 1990-1991 (380 pou mille). Ce sont surtout les maladies infectieuses et parasitaires, principales causes de décès dans la population, qui expliquent l'augmentation pendant la période de crise, les morts violentes ne représentant que moins de 1% du total. Une intervention conduite par la Croix Rouge depuis la fin de l'année 1991 a permis de réduire la mortalité à 269 pour mille en 1994. La baisse récente de la mortalité s'explique essentiellement par la diminution de quatre causes de décès seulement : la rougeole, la diarrhée, le tétanos et la malnutrition. Ces maladies étaient les principales cibles du programme d'intervention de la Croix Rouge, qui portaient notamment sur les vaccinations et sur la supplémentation en vitame "A". (Résumé d'auteur

Two Extraordinary Substellar Binaries at the T/Y Transition and the Y-Band Fluxes of the Coolest Brown Dwarfs

Using Keck laser guide star adaptive optics imaging, we have found that the T9 dwarf WISE J1217+1626 and T8 dwarf WISE J1711+3500 are exceptional binaries, with unusually wide separations (~0.8 arcsec, 8-15 AU), large near-IR flux ratios (~2-3 mags), and small mass ratios (~0.5) compared to previously known field ultracool binaries. Keck/NIRSPEC H-band spectra give a spectral type of Y0 for WISE J1217+1626B, and photometric estimates suggest T9.5 for WISE J1711+3500B. The WISE J1217+1626AB system is very similar to the T9+Y0 binary CFBDSIR J1458+1013AB; these two systems are the coldest known substellar multiples, having secondary components of ~400 K and being planetary-mass binaries if their ages are <~1 Gyr. Both WISE J1217+1626B and CFBDSIR J1458+1013B have strikingly blue Y-J colors compared to previously known T dwarfs, including their T9 primaries. Combining all available data, we find that Y-J color drops precipitously between the very latest T dwarfs and the Y dwarfs. The fact that this is seen in (coeval, mono-metallicity) binaries demonstrates that the color drop arises from a change in temperature, not surface gravity or metallicity variations among the field population. Thus, the T/Y transition established by near-IR spectra coincides with a significant change in the ~1 micron fluxes of ultracool photospheres. One explanation is the depletion of potassium, whose broad absorption wings dominate the far-red optical spectra of T dwarfs. This large color change suggests that far-red data may be valuable for classifying objects of <~500 K.Comment: ApJ, in press (accepted Aug 1, 2012). Small cosmetic changes in version 2 to match final publicatio

Geochemistry and tectonic setting of pre-collision Cretaceous and Paleogene volcanic rocks of Ecuador

Etude et caractérisation géochimique des roches volcaniques de la zone cotière et de la Cordillère occidentale de la Bolivie. Proposition d'un modèle d'évolution géodynamique de cette partie de la chaîne des Andes au cours du Crétacé supérieur