Developing an interatomic potential for martensitic phase transformations in zirconium by machine learning

Interatomic potentials: predicting phase transformations in zirconium Machine learning leads to a new interatomic potential for zirconium that can predict phase transformations. A team led by Hongxian Zong at Xi’an Jiaotong University, China, and Turab Lookman at Los Alamos National Laboratory, U.S.A, used a Gaussian-type machine learning approach to produce an interatomic potential that predicted phase transformations in zirconium. They expressed each atomic energy contribution via changes in the local atomic environment, such as bond length, shape, and volume. The resulting machine-learning potential successfully described pure zirconium’s physical properties. When used in molecular dynamics simulations, it predicted a zirconium phase diagram as a function of both temperature and pressure that agreed well with previous experiments and simulations. Developing learnt interatomic potentials in phase-transforming systems could help us better simulate complex systems

In Vivo Fate Analysis Reveals the Multipotent and Self-Renewal Features of Embryonic AspM Expressing Cells

Radial Glia (RG) cells constitute the major population of neural progenitors of the mouse developing brain. These cells are located in the ventricular zone (VZ) of the cerebral cortex and during neurogenesis they support the generation of cortical neurons. Later on, during brain maturation, RG cells give raise to glial cells and supply the adult mouse brain of Neural Stem Cells (NSC). Here we used a novel transgenic mouse line expressing the CreERT2 under the control of AspM promoter to monitor the progeny of an early cohort of RG cells during neurogenesis and in the post natal brain. Long term fate mapping experiments demonstrated that AspM-expressing RG cells are multi-potent, as they can generate neurons, astrocytes and oligodendrocytes of the adult mouse brain. Furthermore, AspM descendants give also rise to proliferating progenitors in germinal niches of both developing and post natal brains. In the latter –i.e. the Sub Ventricular Zone- AspM descendants acquired several feature of neural stem cells, including the capability to generate neurospheres in vitro. We also performed the selective killing of these early progenitors by using a Nestin-GFPflox-TK allele. The forebrain specific loss of early AspM expressing cells caused the elimination of most of the proliferating cells of brain, a severe derangement of the ventricular zone architecture, and the impairment of the cortical lamination. We further demonstrated that AspM is expressed by proliferating cells of the adult mouse SVZ that can generate neuroblasts fated to become olfactory bulb neurons

Le Lions Clubs au Bénin : un club caritatif qui pratique une liturgie à dessein politique

Comparer les réunions et le protocole du Lions Clubs à un rite offre l’occasion de mesurer la portée politique de cette communauté et de mesurer les effets que les réunions provoquent en dehors de ce cercle. L’observation permet également d’appréhender l’importance du Lions Clubs en Afrique où il ne peut être réduit à un lieu de rencontre entre riches séduits par l’ostentation et à la recherche de nouveaux profits. Les « Lions » sont comparés par la population à des diplomates, parce qu’ils portent des uniformes et des décorations et parce qu’ils sont reçus par les plus hautes autorités politiques des États. Depuis l’Occident, ce comportement est considéré comme une caricature de la gouvernance. Pourtant les réunions sont, pour les membres, des moments de travail et de rencontre qui ressemblent à une religion politique par leur but caché qui est de conquérir l’indépendance de l’Afrique au sein du Lions Clubs. Cet objectif est facilité par l’explosion du nombre de membres africains qui attestent du mouvement social sévissant au sommet de la société. L’élite africaine, en transformant la mission caritative en un rassemblement politique, propose un nouveau panafricanisme.The comparison of meetings and protocol of the Lions Clubs in a ritual, offers an opportunity to measure the political impact of this community and the effect the meetings have outside the circle. The study also allows us to understand the importance of the Lions Clubs in Africa, where it cannot be reduced to a meeting of wealthy people seduced by the opulence and the opportunity to find new sources of profit. Lions are compared by population to diplomats because of their appearance, wearing uniforms and medals and are received by the highest political authorities from other nations. In the West this behaviour is seen as a caricature of governance but for members the meetings offer occasions for work and friendship. This appears like political religion because of the hidden goal: to conquer the independence of Africa in the Lions Clubs. This objective is facilitated by the explosion in the number of African members showing the social movement that rages at the top levels of society. The African elite, by its transformation of charity into political rally, proposes a new form of pan-Africanism