26 research outputs found
Saving the republic:State nostalgia and slavery reparations in media and political discourses
Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond
La fracture en France est encore plus forte Ă gauche
Lâaffaire grecque divise toute la classe politique. Mais comme en Italie et en Espagne, la fracture en France est encore plus forte Ă gauche, une partie du PS tombant dâaccord avec le Front de gauche pour exprimer sa solidaritĂ© avec TsĂpras et glorifier lâattitude du peuple grec. LâintensitĂ© de ce dĂ©bat atteste de la prĂ©gnance dans la culture française de la gauche radicale. Au travers du cas grec, on retrouve ses thĂ©matiques historiques : lâaffirmation dâune solidaritĂ© internationale, dont la traduction au moment de la guerre dâEspagne fut son soutien aux rĂ©publicains espagnols ; dâune solidaritĂ© aussi avec les peuples en souffrance, qui raisonne avec le tropisme trĂšs fort en France du complexe de David contre Goliath. On retrouve aussi lâhostilitĂ© au libĂ©ralisme, ce que lâon appelait lâanticapitalisme ; la critique de lâEurope, une constante de la gauche radicale, non pas au nom de lâanti-europĂ©anisme mais au nom de la construction dâ«une autre Europe» plus sociale ; et puis enfin la cĂ©lĂ©bration de la dĂ©mocratie directe, rĂ©fĂ©rendaire. [Premier paragraphe
Porous Gold Films Fabricated by Wet-Chemistry Processes
Porous gold films presented in this paper are formed by combining gold electroless deposition and polystyrene beads templating methods. This original approach allows the formation of conductive films (2 Ă 106â(Ω·cm)â1) with tailored and interconnected porosity. The porous gold film was deposited up to 1.2âÎŒm on the silicon substrate without delamination. An original zirconia gel matrix containing gold nanoparticles deposited on the substrate acts both as an adhesion layer through the creation of covalent bonds and as a seed layer for the metallic gold film growth. Dip-coating parameters and gold electroless deposition kinetics have been optimized in order to create a three-dimensional network of 20ânm wide pores separated by 20ânm thick continuous gold layers. The resulting porous gold films were characterized by GIXRD, SEM, krypton adsorption-desorption, and 4-point probes method. The process is adaptable to different pore sizes and based on wet-chemistry. Consequently, the porous gold films presented in this paper can be used in a wide range of applications such as sensing, catalysis, optics, or electronics
Chemical evolution of Titan's tholins exposed to solar radiation in Low Earth Orbit onboard the EXPOSE facility and possible incidence on Titan's aerosols composition (Screen 5)
International audienceWith the objective to characterize the aging of Titan's aerosols produced in the upper atmosphere and submitted to solar radiation during their long descent to the satellite surface, Titan's tholins were exposed to the direct solar radiation in low Earth orbit using the ESA's EXPOSE facility that was mounted outside the ISS for months. The interest of such an experiment comes from the exposure of the sample to the real solar radiation spectrum. Two varieties of tholins with different chemical properties were produced with the PAMPRE laboratory experiment, one using a (98:2) N2:CH4 gaseous mixture, and another one with a (90:10) mixture. These samples were exposed to the same solar radiation for the months the EXPOSE facility was mounted outside ISS. Their chemical properties measured before the flight and after their return to the laboratory were compared. Results clearly show that both tholins structure have been modified by the solar radiation. Thanks to control samples placed in the EXPOSE facility in blind cells, and in a facility in the laboratory, this evolution can be definitely attributed to UV radiation. We present here the corresponding results and the consequences we can deduce for the aging of the Titan'
Chemical Aging of Titan's Tholins Exposed to Solar Radiation in Low Earth Orbit onboard the EXPOSE Facility
International audienceTitan's organic aerosols are produced from the chemistry occurring in the atmosphere from gaseous N2 and CH4 submitted to UV solar radiation and energetic particles from Saturn magnetosphere. Our direct knowledge about their chemical composition is limited but we know they are among the most complex organic materials on Titan, composed of a solid core incorporating at least both carbon, hydrogen and nitrogen atoms. This chemistry is unique in the solar system and it could help understanding pathways of the prebiotic chemistry that resulted in the emergence of life. Titan's aerosols composition is indirectly studied through the production and analysis of analogues, called tholins, using laboratory experiments which mimic Titan's atmosphere chemistry conditions. But usually, these tholins are analyzed straight after their production, and it is only recently that the question of their aging was raised. In particular, the aging of the Titan's aerosols submitted to solar radiation during their long descent to the satellite surface was studied in the laboratory using specific UV wavelengths (1). With the same objective, Titan's tholins were exposed to the direct solar radiation in low Earth orbit using the ESA's EXPOSE facility mounted outside the ISS for months. Two varieties of tholins with different chemical properties were produced with the PAMPRE laboratory experiment (2), the first one using a (98:2) N2:CH4 gaseous mixture, and the other one, a (90:10) one. Increasing the amount of initial methane results in a more aliphatic material. These samples were exposed to the same solar radiation for the months the EXPOSE facility was mounted outside ISS. The chemical properties of these samples measured before the flight and after their return to the laboratory were compared. They clearly showed that both tholins structure have been modified in some extent by the solar radiation. Thanks to control samples placed in the EXPOSE facility in blind cells, and in a facility in the laboratory, this evolution can be definitely attributed to UV radiation. We present here the corresponding results and the consequences we can deduce for the aging of the Titan's aerosols Ref:[1]Carrasco N.(2018) Nat. Ast. [2] Szopa C. (2005) Planet. Space Sci
The AMINO experiment: methane photolysis under Solar VUV irradiation on the EXPOSE-R facility of the International Space Station
International audienceThe scientific aim of the present campaign is to study the whole chain of methane photo-degradation, as initiated by Solar vacuum-ultraviolet irradiation in Titan's atmosphere. For this purpose, the AMINO experiment on the EXPOSE-R mission has loaded closed cells for gas-phase photochemistry in space conditions. Two different gas mixtures have been exposed, named Titan 1 and Titan 2, involving both N2-CH4 gas mixtures, without and with CO2, respectively. CO2 is added as a source of reactive oxygen in the cells. The cell contents were analysed thanks to infrared absorption spectroscopy, gas chromatography and mass spectrometry. Methane consumption leads to the formation of saturated hydrocarbons, with no detectable influence of CO2. This successful campaign provides a first benchmark for characterizing the whole methane photochemical system in space conditions. A thin film of tholin-like compounds appears to form on the cell walls of the exposed cells
Recherche, politique et pratiques en Ă©ducation : services rendus et questions posĂ©es dâun univers Ă lâautre
Ă lâoccasion de son 200e numĂ©ro, la Revue française de pĂ©dagogie, revue gĂ©nĂ©raliste de recherche en Ă©ducation de rĂ©fĂ©rence dans le monde francophone, a souhaitĂ© renouer avec lâune des interrogations fondamentales qui la caractĂ©risent depuis sa crĂ©ation en 1967 : celle des rapports entre recherche, politique, administration et pratique professionnelle en Ă©ducation. FondĂ© sur un appel Ă contributions inĂ©dit, ce numĂ©ro a la particularitĂ© de ne pas regrouper uniquement des articles Ă©manant de chercheurs, mais de croiser ceux-ci avec des contributions dâacteurs aux profils divers. Les analyses prĂ©sentĂ©es permettent ainsi de couvrir une grande diversitĂ© de situations nationales et institutionnelles, notamment : rĂŽle et fonctionnement de diffĂ©rents « Conseils supĂ©rieurs » en France ou au QuĂ©bec, dĂ©bats et controverses mĂ©diatiques et scientifiques Ă propos dâune loi sur « lâĂ©cole inclusive » en RĂ©publique tchĂšque, construction de sĂ©quences didactiques fondĂ©es sur la recherche au Mexique, accompagnement dâĂ©tablissements scolaires par la recherche dans le canton de Vaud en Suisse ou encore place de la recherche dans des revues dâinterface. Deux axes majeurs structurent le numĂ©ro : lâĂ©tude de divers espaces, supports ou acteurs assurant une fonction de mĂ©diation entre les univers Ă©tudiĂ©s ; lâanalyse de la place et des transformations de la recherche en contexte non strictement acadĂ©mique (situations dâexpertise ou de formation par exemple). En cela, ce numĂ©ro apporte une contribution fondamentale aux nombreux questionnements actuels sur les rĂŽles et la structuration de la recherche en Ă©ducation dans une sociĂ©tĂ© dite de la connaissance. For its 200th issue, the Revue française de pĂ©dagogie, a generalist journal of research in education and one of the leading publication on the subject in the French-speaking world, decided to take a fresh look at one the fundamental questions which have defined it since it was first published in 1967: the relationship between academic research, politics, administration and professional practice in education. Based on a new call for papers, this issue consists of articles by scholars and contributions from stakeholders from a range of backgrounds (experts, policy makers, activists etc.). The articles cover a wide variety of domestic and institutional situations including: the role and functioning of âHigh Councilsâ for education in France and Quebec; media and academic debate and controversy surrounding an "inclusive education" law in the Czech Republic; the design of teaching sequences in Mexico; research-based support for schools in the Swiss canton of Vaud; or the place of research in some professional journals which interface with the academic world. Two main themes run through the issue: the study of various spaces, resources or stakeholders which perform a mediating role between academic research and other areas, and the analysis of the place of and changes in research in a non-academic context (expertise or training situations, for instance). In this regard, this issue makes a significant contribution to the many current studies on the role of academic research and how it is organised in a so-called knowledge society