Le nouveau régime de l’appel public à l’épargne.

Le nouveau régime de l’appel public à l’épargne français a un champ d’application plus restreint mais aussi des obligations légales renforcées. Cette réforme, qui entraîne des conséquences notables pour la Place de Paris, participe de la stabilité financière.Appel public à l’épargne, prospectus, investisseur qualifié, émetteur.

A l'école et au supermarché: le développement des connaissances sur deux organisations sociales. At school and at the supermarket: the ontogenesis of knowledge about two social organizations

International audienc

Epitaxial YBa2Cu3O7-8/SrTiO3 heterostructures grown by pulsed laser deposition for voltage agile microwave filter applications

The performance of tunable microwave devices based on heteroepitaxial YBa2Cu3Ox/SrTiO3 films on (001) LaAlO3 substrate has been evaluated. It has been ascertained that 'out-of-plane' SrTiO3 lattice parameter is the relevant factor in determining both the agility and dielectric loss of the SrTiO3 layers. After high temperature annealing (1100 °C, 1 atm O2), only SrTiO3 layers deposited under low oxygen pressure (∼ 10-5 Torr) show an appreciable reduction of the dielectric losses whilst maintaining high agility. Annealed samples exhibit voltage independent losses of ∼ 5.10-3 simultaneously with 55% dielectric agility at 6 GHz and 77K

Stable isotope analysis of carnivores from the Turkana Basin, Kenya: Evidence for temporally-mixed fossil assemblages

 Stable isotope palaeoecology of fossil mammals is a key research tool for understanding the environmental context of hominin evolution in the Plio-Pleistocene of Africa. Well studied mammal groups include bovids, suids, equids, proboscideans and primates, but to date there has been no in-depth study of modern and fossil carnivores. Here we produce an Africa-wide oxygen and carbon enamel isotope dataset for modern carnivores and compare it with fossil carnivore data sampled from the Plio-Pleistocene Omo Group of the Turkana Basin, Kenya. Comparison of modern carnivore carbon isotopes with satellite images of land cover indicates that carnivore δ13C is related to the proportion of woody cover in the local environment. Modern carnivore oxygen isotopes are strongly influenced by the δ18O of meteoric water, through drinking from standing water and through prey body fluids. Carbon isotope data from fossil carnivores shows close agreement with palaeovegetation reconstructions from δ13C of palaeosol carbonates from the same geological Members, and a similar long-term trend in δ13C values through time (4 Ma to 1 Ma), reflecting a gradual increase in the proportion of C4 grasses in the Turkana Basin. This increase in the δ13C of large carnivores is consistent with the evidence from other mammalian groups for an increase in the proportion of grazers compared to browsers and mixed feeders during this time interval. Two distinct trends within oxygen versus carbon isotope space indicates that the fossil carnivores lived during two distinct climatic regimes – one in which palaeo-lake Turkana was freshwater, and one in which the lake resembled its modern-day hyperalkaline state. These two climatic states most likely represent the end-members of precessionally-driven rainfall extremes over the Ethiopian Highlands. This indicates that each studied faunal assemblage from the Omo Group is a time- and climate-averaged palimpsest; this has significant implications for the interpretation of environmental signals and community palaeoecology derived from Turkana Basin fossil mammals, including early hominins.