52 research outputs found

    Gossamer Technology to Deorbit LEO Non-Propulsion Fitted Satellite

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    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

    Rapport d'activité : le projet d'appui à la filière porcine (du 01/09/96 au 15/12/1998)

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    Ce rapport décrit la phase ultime des actions de repeuplement porcin réalisées en République d'Haïti dans le cadre du projet d'Appui à la Filière Porcine, financé par l'Agence Française de Développement. Ce projet, intégré au Programme de Développement de l'Elevage Porcin (financé par la Banque Interaméricaine de Développement), couvre la période 1996-1998 pour un budget de 10,5 MF. La diffusion de reproducteurs de race rustique en milieu rural a été assurée par un centre de multiplication primaire et une quinzaine de centres secondaires. L'exploitation de ces centres a mis en évidence le coût élevé du développement d'une génétique porcine rustique en Haïti. Néanmoins, le financement externe a permis de maintenir l'offre de reproducteurs de qualité à un prix de vente fixé très bas par les autorités haïtiennes. Les contraintes de la production traditionnelle (faibles ressources alimentaires, foncier, organisation ... ) restent fortes, limitant ainsi une valorisation optimale de la qualité de la génétique diffusée. Cette offre (qui ne peut dans les conditions actuelles s'autofinancer) doit cependant se maintenir au risque de voir disparaître rapidement les effets d'une dizaine d'années d'amélioration génétique. La diffusion d'une race rustique en milieu paysan, désormais confiée aux autorités haïtiennes, ne pourra se poursuivre à court terme que si elle est subventionnée pour préserver la capacité d'investissement des éleveurs. Le développement d'une production plus spécialisée, de type semi-industriel, demeure, à ce jour, entravée en amont par un coût des aliments trop élevé, un approvisionnement local de ceux-ci irrégulier, un individualisme assez fort des partenaires et, en aval, par un marché solvable difficile à séduire et une concurrence très fort

    Sub-genomic origin and regulation patterns of a duplicated WRKY gene in the allotetraploid species #Coffea arabica$

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    International audienceThe extensively cultivated coffee species Coffea arabica is an allotetraploid resulting from a recent hybridization between two wild diploid Coffea species. We describe in this paper the first identification and functional assessment of homoeologous gene copies in C. arabica. When cloning the CaWRKY1 gene encoding a transcription factor of the WRKY superfamily associated with plant defense responses to pathogens (Ganesh et al. in Plant Sci 170:1045-1051, 2006), two distinct gene copies (CaWRKY1a and CaWRKY1b) were obtained from C. arabica. Southern blots experiments and phylogenetic analysis of the WRKY1 gene in related diploid Coffea species showed that CaWRKY1a and CaWRKY1b are homoeologous sequences in the allopolyploid coffee genome and are probably close descents of the extant Coffea canephora and C. eugenioides WRKY1 genes. To verify if CaWRKY1a and CaWRKY1b were both functional, gene expressions were monitored in C. arabica plants challenged by the rust fungus Hemileia vastatrix, the root-knot nematode Meloidogyne exigua, and after several abiotic treatments. Real-time quantitative polymerase chain reaction (PCR) assays showed that CaWRKY1 homoeologs were concomitantly expressed and displayed the same altered patterns of expression in leaves and roots during biotic and abiotic treatments. These results suggest that CaWRKY1a and CaWRKY1b were functionally retained in the coffee genome after allopolyploidization and that no functional divergence occurred between the duplicated genes in the C. arabica genome. This study provides the first molecular data on sub-genome-specific expression in allopolyploid coffee. The origin of the C. arabica sub-genomes is discussed with regards on the probable progenitors of this important crop species

    Interspecific hybridization and rootstock breeding for peach

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    On design of analogue multipliers using gallium arsenide MESFETs

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