Comparison between classical potentials and ab initio for silicon under large shear

The homogeneous shear of the {111} planes along the <110> direction of bulk silicon has been investigated using ab initio techniques, to better understand the strain properties of both shuffle and glide set planes. Similar calculations have been done with three empirical potentials, Stillinger-Weber, Tersoff and EDIP, in order to find the one giving the best results under large shear strains. The generalized stacking fault energies have also been calculated with these potentials to complement this study. It turns out that the Stillinger-Weber potential better reproduces the ab initio results, for the smoothness and the amplitude of the energy variation as well as the localization of shear in the shuffle set

Dislocation formation from a surface step in semiconductors: an ab initio study

The role of a simple surface defect, such as a step, for relaxing the stress applied to a semiconductor, has been investigated by means of large scale first principles calculations. Our results indicate that the step is the privileged site for initiating plasticity, with the formation and glide of 60$^\circ$ dislocations for both tensile and compressive deformations. We have also examined the effect of surface and step termination on the plastic mechanisms

Entre faits divers et débats publics : comment la presse écrite aborde la psychiatrie ?

Dans la littérature scientifique et psychiatrique, on admet généralement que la presse, exploitant notamment les faits divers, pèse négativement sur les représentations que la population nourrit concernant les personnes affectées de troubles mentaux. L’article vise à nuancer cette thèse à partir de l’analyse d’un corpus de quatre quotidiens. Dans un premier temps, nous comparerons l’écho donné par la presse aux réformes législatives en matière de psychiatrie et la place accordée aux faits divers. Dans un deuxième temps, nous préciserons les sujets relatifs à la psychiatrie les plus traités par ces quotidiens. Nous nous arrêterons enfin sur le traitement quantitatif des faits divers par ces derniers. Ces éléments permettront de souligner la variabilité du traitement des questions de psychiatrie ainsi que des faits divers selon l’orientation politique des quotidiens.Scientific and psychiatric studies use to consider that press has a negative impact on common representations of people with mental diseases. This paper aims to discuss this thesis based on a qualitative and quantitative analysis of 4 French daily newspapers. We compare firstly the papers devoted to legislative reforms, in psychiatric, and the papers devoted to news items. Then we analyse the psychiatric topics the daily newspapers deal with. Finally we propose a quantitative analysis of news items published by each newspaper. Based on these elements we show the different approaches of the psychiatric topics and of the news items in each daily newspaper