32 research outputs found
Interaction between forced and natural convection in a thin cylindrical fluid layer at low Prandtl number
Motivated by nuclear safety issues, we study the heat transfers in a thin
cylindrical fluid layer with imposed fluxes at the bottom and top surfaces (not
necessarily equal) and a fixed temperature on the sides. We combine direct
numerical simulations and a theoretical approach to derive scaling laws for the
mean temperature and for the temperature difference between the top and bottom
of the system. We find two asymptotic scaling laws depending on the flux ratio
between the upper and lower boundaries. The first one is controlled by heat
transfer to the side, for which we recover scaling laws characteristic of
natural convection. The second one is driven by vertical heat transfers
analogous to Rayleigh Benard convection. We show that the system is inherently
inhomogeneous, and that the heat transfer results from a superposition of both
asymptotic regimes. Keeping in mind nuclear safety models, we also derive a
one-dimensional model of the radial temperature profile based on a detailed
analysis of the flow structure, hence providing a way to relate this profile to
the imposed boundary conditions.Comment: 27 pages, 18 Figure
Apprendre à gérer des collections patrimoniales en bibliothÚque
Vous venez d'ĂȘtre nommĂ©-e responsable de la collection patrimoniale d'une bibliothĂšque mais vous n'ĂȘtes pas spĂ©cialiste ou vos connaissances sont lointaines. D'oĂč viennent ces vieux livres qui dorment dans la rĂ©serve ? Qu'en faire ? A-t-on le droit de s'en dĂ©barrasser s'ils paraissent ne servir Ă personne ? Y en a-t-il qui sont rares et qu'il faudrait mettre en valeur ? Quelques-uns sont cataloguĂ©s mais c'est loin d'ĂȘtre le cas de tous, comment faire ? Et puis il y a des gravures dans des portefeuilles, des photographies anciennes ici et lĂ . Comment savoir si elles ont quelque intĂ©rĂȘt ? Dans un coin des magasins, des moisissures sont brusquement apparues et semblent contaminer peu Ă peu les ouvrages. Comment s'en dĂ©barrasser ? Qui prĂ©venir ? Si vous vous posez parfois ces dĂ©licates questions, ce manuel est pour vous. (Dominique Coq, responsable scientifique du volume) ĂclairĂ© par des retours d'expĂ©riences de spĂ©cialistes, ce manuel rĂ©unit un ensemble raisonnĂ© d'informations de base, qui prĂ©sente la marche Ă suivre pour apprĂ©hender, traiter, signaler et valoriser ces fonds patrimoniaux ; il permet d'en comprendre l'environnement juridique, administratif et documentaire. Un document indispensable pour les professionnels peu formĂ©s dans le domaine, confrontĂ©s pour la premiĂšre fois Ă une collection patrimoniale, ou qui s'y destinent, et dĂ©sireux d'acquĂ©rir les rudiments nĂ©cessaires pour la gĂ©rer
Conseil à l'officine face à une éruption vésiculo-bulleuse
PARIS-BIUP (751062107) / SudocSudocFranceF
Interaction between forced and natural convection in a thin cylindrical fluid layer at low Prandtl number
International audienceMotivated by nuclear safety issues, we study the heat transfers in a thin cylindrical fluid layer with imposed fluxes at the bottom and top surfaces (not necessarily equal) and a fixed temperature on the sides. We combine direct numerical simulations and a theoretical approach to derive scaling laws for the mean temperature and for the temperature difference between the top and bottom of the system. We find two asymptotic scaling laws depending on the flux ratio between the upper and lower boundaries. The first one is controlled by heat transfer to the side, for which we recover scaling laws characteristic of natural convection (Batchelor, Q. Appl. Maths , vol. 12, 1954, pp. 209â233). The second one is driven by vertical heat transfers analogous to RayleighâBĂ©nard convection (Grossmann & Lohse, J. Fluid Mech. , vol. 407, 2000, pp. 27â56). We show that the system is inherently inhomogeneous, and that the heat transfer results from a superposition of both asymptotic regimes. Keeping in mind nuclear safety models, we also derive a one-dimensional model of the radial temperature profile based on a detailed analysis of the flow structure, hence providing a way to relate this profile to the imposed boundary conditions
Characterisation of protected denomination of origin cheeses: relationships between sensory texture and instrumental data
International audienc
Characterisation of protected denomination of origin cheeses:relationships between sensory texture and instrumental data
International audienc
Highlighting of quorum sensing lux genes and their expression in the hydrothermal vent shrimp Rimicaris exoculata ectosymbiontic community. Possible use as biogeographic markers.
Rimicaris exoculata is a caridean shrimp that dominates the fauna at several hydrothermal vent sites of the Mid-Atlantic Ridge. It has two distinct and stable microbial communities. One of these epibiontic bacterial communities is located in the shrimp gut and has a distribution and role that are poorly understood. The second colonizes its enlarged gill chamber and is involved in host nutrition. It is eliminated after each molt, and has colonization processes reminiscent of those of a biofilm. The presence and expression of genes usually involved in quorum sensing (QS) were then studied. At four sites, Rainbow, TAG, Snake Pit and Logatchev, two lux genes were identified in the R. exoculata epibiontic community at different shrimp molt stages and life stages. RT-PCR experiments highlighted lux gene expression activity at TAG, Snake Pit and Rainbow vent sites. Their potential QS activity and their possible roles in epibiont colonization processes are discussed. Moreover, phylogenetic analysis has shown the presence of three clades for luxS (Epsilonproteobacteria) and four clades for luxR (Gammaproteobacteria) genes, each clade being restricted to a single site. These genes are more divergent than the 16S rRNA one. They could therefore be used as biogeographical genetic markers
Corpus callosum size may predict late-life depression in women: A 10-year follow-up study
Background Recent research on late-life depression (LLD) pathophysiology suggests the implication of abnormalities in cerebral white matter and particularly in interhemispheric transfer. Corpus callosum (CC) is the main brain interhemispheric commissure
Les carnets aujourdâhui
Petit objet nomade Ă lâapparence souvent anodine, le carnet a dĂ©voilĂ© au fil du temps ses nombreuses potentialitĂ©s matĂ©rielles et crĂ©atives, exploitĂ©es autant par les Ă©crivains que les scientifiques, autant par les artistes que les thĂ©oriciens. Lâexploration de ces potentialitĂ©s en contexte dâapprentissage ou de formation rĂ©unit, depuis 2012, des chercheurs et des enseignants Ă lâĂ©cole supĂ©rieure du professorat et de lâĂ©ducation (ESPE) de lâuniversitĂ© de Caen Normandie. Leurs Ă©changes et leurs rĂ©flexions ont fait Ă©merger trois dimensions clĂ©s du carnet : la construction dâun sujet lecteur / scripteur Ă partir de carnets de lecture ou dâĂ©criture, lâapprentissage (inter)disciplinaire facilitĂ© par lâutilisation du carnet en classe, et enfin les liens complexes qui se tissent entre carnet, mobilitĂ© et interculturalitĂ©. De maniĂšre inĂ©dite, cet ouvrage croise les regards sur lâobjet carnet en proposant des dispositifs institutionnels, des recherches acadĂ©miques, anthropologiques et didactiques, mais aussi des comptes rendus dâexpĂ©riences sur le terrain, en classe comme en formation