Search results for "Fonction"

Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates

2012

Marine N<sub>2</sub> fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N<sub>2</sub>) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic …

Variations spatiales et temporelles des communautés adventices des cultures annuelles en France

2007

Although arable weed species are particularly well adapted to habitats characterised by high levels of disturbance(ploughing, harvest), the degree and rate at which agro-ecosytems have been transformed in the last 50 years in Europe(use of chemicals, changes in crop rotations) has led to profound changes in the composition and diversity of arable weedcommunities. This thesis provides an update on the composition and diversity of weed communities that can be foundacross the main crop types and regions of France. It also addresses two objectives i) applying (community) ecologytheories for the analysis and interpretation of spatial and temporal variations in weed communities and ii) using the …

Les activités de rééducation GAPP à l'école primaire : analyse du fonctionnement et évaluation des effets

1991

Alain Mingat : Die Umschulungsaktivitäten der GAPP (Gruppen zur psychopädagogischer Hilfe) in der Grundschule. Die GAPP wurden vor za. 20 Jahren geschaffen mit dem Zweck, die Schüler zu unterstützen, die vorübergehende Schwierigkeiten zur guten Eingliederung in die Schule aufweisen. Diese Einrichtung wurde bisher lediglich diskursiv analysiert. Der vorliegende Artikel zeigt, dass starke Unterschiede im Funktionieren der Dienstleistungen bestehen (Mittelzuweisung durch die Verwaltung, Umschulungspraxis, allgemein und zwischen den einzelnen GAPP-Einrichtungen) mit der Konsequenz, dass die Zulassungsentscheidungen sehr ungenau sind : das erleichtet nebenbei die Bewertung der Auswirkungen. Dies…

Etude asymptotique et transcendance de la fonctionvaleur en contrôle optimal. Catégorie log-exp en géométrie sous-Riemannienne dans le cas Martinet.

2000

The main subject of this work is the study and the role ofabnormal trajectories in optimal control theory.We first recall some fundamental results in optimal control. Thenwe investigate the optimality of abnormal trajectories forsingle-input affine systems with constraint on the control, firstfor the time-optimal problem, and then for any cost, the finaltime being fixed or not.Using such an affine system,we extend this theory to sub-Riemannian systems of rank 2.These results show that, under general conditions, an abnormaltrajectory is \it{isolated} among all solutions of the systemhaving the same limit conditions, and thus is \it{locallyoptimal}, until a first \it{conjugate point} which ca…

Impact of t-PA administration on brain BDNF levels in physiological conditions and in circulating BDNF levels in ischemic conditions : Human and anim…

2014

Our objective was to test the hypothesis that the beneficial effect of the administration of the recombinant form of tissue plasminogen activator (rt-PA) in ischemic stroke patient not only results from its fibrinolytic activity but also from its ability to increase brain-derived neurotrophic factor (BDNF) in the brain. To this end, we conducted an initial study to evaluate the effect of rt-PA on brain BDNF levels in healthy animals. In a second study, we investigated the effect of rt-PA on serum BDNF levels in ischemic stroke patients and in animals subjected to permanent focal cerebral ischemia. Blood samples were obtained from patient on admission (D0), D1, D7 and D90 after stroke and in…

Towards a Better Understanding of the Functioning of School Systems for Better Decision Making : The Case of Primary Schools in Togo

1991

International audience

Togo

1995

Towards a Better Understanding of the Functioning of School Systems for Better Decision Making : The Case of Private Schools in Togo

1993

International audience

L'école primaire en Afrique

1992

The tools like evidences of metal working? : strike supports, abrasives and burnishers, sharpening tools and crushing tools

2013

Lots of lithic tools are present in Metal Ages, but few are studied. In metal production, they are especially constitued by strike supports, abrasives, burnishers, sharpening tools and crushing tools. A part of them are in metal ( strike supports) or in ceramic (abrasives, sharpening tools). Contemporary forms of these tools are too different to permit a dierct comparison. It is necessary to work on the function of the tools, deduced from the analysis of these structure. Strike supports used for metal working are easily identifiable. They allow to reproduce more or less precisely the objects that they were fabricated with. Abrasives are difficult to relate to a material, but the traces of u…