Study of some optimal XFEM type methods

The XFEM method in fracture mechanics is revisited. A first improvement is considered using an enlarged fixed enrichment subdomain aroud the crack tip and a bonding condition for the corresponding degree of freedom. An efficient numerical integration rule is introduced for the nonsmooth enrichment functions. The lack of accuracy due to the transition layer between the enrichment aera and the rest of the domain leads to consider a pointwise matching condition at the boundary of the subdomain. An optimal numerical rate of convergence is then obtained using such a nonconformal method

Cdk1, Plks, Auroras, and Neks: the mitotic bodyguards.

In: Li JJ, Li SA, Mohla S, Rochefort H, Maudelonde T, (eds), 2008, Hormonal Carcinogenesis V : Proceedings of the Fifth International Symposium, New York, Springer-Verlag. (Adv. Exp. Med. Biol. 617)International audienceThe coordination of progression through mitosis is mainly orchestrated by protein phosphorylation insured by several serine/threonine kinases. In this short review we will focus on the four main mitotic kinase families: the cyclin-dependent kinase: Cdks, the polo-like kinases: Plks, the Aurora kinases and the NIMArelated kinases: Nerks

High order extended finite element method for cracked domains

The aim of the paper is to study the capabilities of the Extended Finite Element Method (XFEM) to achieve accurate computations in non smooth situations such as crack problems. Although the XFEM method ensures a weaker error than classical finite element methods, the rate of convergence is not improved when the mesh parameter h is going to zero because of the presence of a singularity. The difficulty can be overcome by modifying the enrichment of the finite element basis with the asymptotic crack tip displacement solutions as well as with the Heaviside function. Numerical simulations show that the modified XFEM method achieves an optimal rate of convergence (i.e. like in a standard finite element method for a smooth problem

EIF4E/4E-BP dissociation and 4E-BP degradation in the first mitotic division of the sea urchin embryo

AbstractThe mRNA’s cap-binding protein eukaryotic translation initiation factor (eIF)4E is a major target for the regulation of translation initiation. eIF4E activity is controlled by a family of translation inhibitors, the eIF4E-binding proteins (4E-BPs). We have previously shown that a rapid dissociation of 4E-BP from eIF4E is related with the dramatic rise in protein synthesis that occurs following sea urchin fertilization. Here, we demonstrate that 4E-BP is destroyed shortly following fertilization and that 4E-BP degradation is sensitive to rapamycin, suggesting that proteolysis could be a novel means of regulating 4E-BP function. We also show that eIF4E/4E-BP dissociation following fertilization is sensitive to rapamycin. Furthermore, while rapamycin modestly affects global translation rates, the drug strongly inhibits cyclin B de novo synthesis and, consequently, precludes the completion of the first mitotic cleavage. These results demonstrate that, following sea urchin fertilization, cyclin B translation, and thus the onset of mitosis, are regulated by a rapamycin-sensitive pathway. These processes are effected at least in part through eIF4E/4E-BP complex dissociation and 4E-BP degradation

Isolation and Characterization of New Leptospira Genotypes from Patients in Mayotte (Indian Ocean)

Leptospirosis has been recognized as an increasing public health problem affecting poor people from developing countries and tropical regions. However, the epidemiology of leptospirosis remains poorly understood in remote parts of the world. In this study of patients from the island of Mayotte, we isolated 22 strains from the blood of patients during the acute phase of illness. The pathogenic Leptospira strains were characterized by serology and various molecular typing methods. Based on serological data, serogroup Mini appears to be the dominant cause of leptospirosis in Mayotte. Further molecular characterization of these isolates allowed the identification of 10 pathogenic Leptospira genotypes that could correspond to previously unknown serovars. Further progress in our understanding of the epidemiology of Leptospira circulating genotypes in highly endemic regions should contribute to the development of novel strategies for the diagnosis and prevention of this neglected emerging disease

Analyse fonctionnelle du facteur elF4F au cours du développement embryonnaire précoce de l'oursin Sphaerechinus granularis

During this decade, the involvement of translation initiation factors was highlighted in the process of cell division, tumorigenesis and during embryonic development. Among these factors, the eIFA4E initiation factor is now recognized for a central role in the control of the regulation of gene expression and to be involved in the regulation of embryonic development.We analyzed the behavior of this factor and its main repressor 4E-BP, during the early embryonic development of the sea urchin. Our work shows that the sea urchin egg, fertilization causes dissociation of the complex eIFA4E / 4E-BP and the degradation of 4E-BP, original mechanism described here for the first time. Degradation and dissociation are sensitive to rapamycin, suggesting that they are both controlled by the kinase FRAP / mTOR. Alongside this work we analyzed the enzyme regulation upstream of eIFA4E / 4E-BP complex and determined that the PI3 kinase seems to exert very little control over this complex, contrary to what is reported in the literature.Furthermore, we show that the complex eIFA4E / 4E-BP controls the synthesis of cyclin B, essential for the accomplishment of the first mitosis of sea urchin egg. Another factor iniatiation, eIFA4G, also plays a key role for the first mitotic division.Finally, we have identified a new protein associating with eIFA4E: H4E-BP. We show that the amount of 4E-BP and BP-H4E and their degree of association with eIF4E is regulated during early development. Together, our results provide insight into how to articulate the cell cycle process and those of protein synthesis during early embryonic development.Au cours de cette décennie, l'implication des facteurs d'initiation de la traduction a été soulignée dans les processus de la division cellulaire, de la tumorigénèse ainsi qu'au cours du développement embryonnaire. Parmi ces facteurs, le facteur d'initiation eIFA4E est maintenant reconnu pour un rôle central dans le contrôle de la régulation de l'expression des gènes et pour être impliqué dans la régulation du développement embryonnaire. Nous avons analysé le comportement de ce facteur et de son principal répresseur, 4E-BP, au cours du développement embryonnaire précoce de l'oursin. Nos travaux démontrent que chez l'oursin, la fécondation provoque la dissociation du complexe eIFA4E / 4E-BP ainsi que la dégradation de 4E-BP, mécanisme original décrit ici pour la première fois. La dégradation et la dissociation sont sensibles à la rapamycine, suggérant qu'elles sont toutes deux sous contrôle de la kinase FRAP / mTOR. Parallèlement à ces travaux nous avons analysé la régulation enzymatique située en amont du complexe eIFA4E / 4E-BP et déterminé que la PI3 kinase semble n'exercer qu'un très faible contrôle sur ce complexe contrairement à ce qui est relaté dans la littérature. Par ailleurs, nous montrons que le complexe eIFA4E / 4E-BP contrôle la synthèse de la cycline B, indispensable pour l'accomplissement de la première mitose de l'oeuf d'oursin. Un autre facteur d'iniatiation, eIFA4G, joue lui aussi un rôle déterminant pour la première division mitotique. Enfin, nous avons identifié une nouvelle protéine s'associant à eIFA4E: H4E-BP. Nous montrons que la quantité de 4E-BP et H4E-BP, et leur degré d'association avec eIF4E sont régulés au cours du développement précoce. L'ensemble de nos résultats permettent de mieux comprendre comment s'articulent les processus du cycle cellulaire et ceux de la synthèse protéique au cours du développement embryonnaire précoce

Analyse fonctionnelle du facteur elF4F au cours du développement embryonnaire précoce de l'oursin sphaerechinus granularis

RENNES1-BU Sciences Philo (352382102) / SudocROSCOFF-Observ.Océanol. (292393008) / SudocSudocFranceF

Une empreinte inédite de l’anneau sigillaire de Childéric Ier conservée au Musée Dobrée à Nantes

Perin Patrick, Salaün Gildas. Une empreinte inédite de l’anneau sigillaire de Childéric Ier conservée au Musée Dobrée à Nantes. In: Bulletin de la Société Nationale des Antiquaires de France, 2008, 2015. pp. 111-119

Le public au bout du fil : le paradoxe de base

Pajon Patrick, Salaün Jean-Michel. Le public au bout du fil : le paradoxe de base. In: Réseaux, volume 8, n°39, 1990. L'invention du spectacteur. pp. 57-76