Simulation de la mise en forme et de la tenue mécanique de pièces obtenues par semi-découpe

National audienceLe procédé de semi-découpe de tôles d'acier est utilisé pour la mise en forme de composants de sièges d'automobiles. La tenue mécanique sous sollicitation radiale de pièces semi- découpées est étudiée par la réalisation d'essais de mise en forme et d'arrachement. La réponse des pièces aux sollicitations est prédite par simulation numérique. La prise en compte de la mise en forme dans la simulation de l'arrachement entraîne un gain de rigidité en adéquation avec l'expérience. La rupture des pièces intervient dans une zone de faible triaxialite.See http://hal.archives-ouvertes.fr/docs/00/59/27/17/ANNEX/r_VB1CWP70.pd

The arithmetic of centrosome biogenesis

How do cells regulate centrosome number? A canonical duplication cycle generates two centrosomes from one in most proliferating cells. Centrioles are key to this process, and molecules such as centrins, SAS-4 and ZYG-1 govern daughter centriole formation. Cdk2 activity probably couples centrosome duplication with the S phase, and a licensing mechanism appears to limit centrosome duplication to once per cell cycle. However, such mechanisms must be altered in some cells--for example, spermatocytes--in which centrosome duplication and DNA replication are uncoupled. There are also alternative pathways of centrosome biogenesis. For example, one centrosome is reconstituted from two gametes at fertilization; in this case, the most common strategy involves differential contributions of centrioles and pericentriolar material (PCM) from each gamete. Furthermore, centrioles can sometimes form de novo from no apparent template. This occurs, for instance, in the early mouse embryo and in parthenogenetic species and might rely on a pre-existing seed that resides within PCM but is not visible by ultrastructural analysis

Conserved domains control heterochromatin localization and silencing properties of SU(VAR)3-7

The Drosophila protein SU(VAR)3-7 is essential for fly viability, chromosome structure, and heterochromatin formation. We report that searches in silico and in vitro for homologues of SU(VAR)3-7 were successful within, but not outside, the Drosophila genus. Protein sequence homology between the distant sibling species Drosophila melanogaster and Drosophila virilis is low, except for the general organization of the protein and three conserved motives: seven widely spaced zinc fingers in the N-terminal half and the BESS and BoxA motives in the C-terminal half of the protein. We have undertaken a fine functional dissection of SU(VAR)3-7 in vivo using transgenes encoding truncations of the protein. BESS mediates interaction of SU(VAR)3-7 with itself, and BoxA is required for specific heterochromatin association. Both are necessary for the silencing properties of SU(VAR)3-7. The seven zinc fingers, widely spaced over the N-terminal half of SU(VAR)3-7, are required for binding to polytene chromosomes. One finger is necessary and sufficient to determine the appropriate chromatin association of the C-terminal half of the protein. Conferring a function to each of the conserved motives allows us to better understand the mode of action of SU(VAR)3-7 in triggering heterochromatin formation and subsequent genomic silencin

Les "vagues voyageuses" du campagnol terrestre en Franche-Comté

Dans les prairies d'altitude, les dégâts provoqués par le campagnol terrestre posent un problème économique et agricole récurrent depuis le début des années 70. Dans la lutte contre cette peste agricole, l'utilisation croissante d'un anticoagulant rodenticide, la bromadiolone, a en plus considérablement augmenté la mortalité de nombreuses espèces animales, notamment de rapaces (légalement protégés), de renards et de sangliers. Dès le début du siècle, les recherches sur les variations de populations de rongeurs ont montré que la densité de certaines espèces de petits mammifères (lemmings, campagnols, etc.) fluctue de manière plus ou moins cyclique

Revisiting the loading dose of amikacin for patients with severe sepsis and septic shock

It has been proposed that doses of amikacin of >15 mg/kg should be used in conditions associated with an increased volume of distribution (Vd), such as severe sepsis and septic shock. The primary aim of this study was to determine whether 25 mg/kg (total body weight) of amikacin is an adequate loading dose for these patients.Clinical TrialJournal ArticleMulticenter StudyResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Transmission Ecology of Echinococcus multilocularis in Wildlife : What Can Be Learned from Comparative Studies and Multiscale Approaches?

アラスカ、中国、北海道、そして、フランス東部での調査結果をもとに野生動物間でのエキノコックス（多包条虫）の伝播生態について述べた。エキノコックスの伝播は、ハビタットの異質性が低く、周期的個体数変動をする感受性の高い中間宿主にとって好適なハビタットの割合が高いランドスケープでより生じやすいことや、伝播過程は宿主の生態に強く依存し、キツネの行動様式や主たる餌資源の分布などによって、感染の季節的変化を含め地域での伝播様式に違いの生じることを示した。また、異なるスケールでのランドスケープや群集の解析によるエキノコックスの伝播に関する総合的な研究の重要性について指摘した

Sumoylation of Drosophila SU(VAR)3-7 is required for its heterochromatic function

In Drosophila, SU(VAR)3-7 is an essential heterochromatin component. It is required for proper chromatin condensation, and changing its dose modifies position-effect variegation. Sumoylation is a post-translational modification shown to play a role in diverse biological processes. Here, we demonstrate that sumoylation is essential for proper heterochromatin function in Drosophila through modification of SU(VAR)3-7. Indeed, SU(VAR)3-7 is sumoylated at lysine K839; this modification is required for localization of SU(VAR)3-7 at pericentric heterochromatin, chromosome 4, and telomeres. In addition, sumoylation of SU(VAR)3-7 is a prerequisite for its ability to enhance position-effect variegation. Thus, these results show that the heterochromatic function of SU(VAR)3-7 depends on its own sumoylation, and unveil a role for sumoylation in Drosophila heterochromatin

Characterization of the exopolysaccharides from Rhodotorula minuta IBRC-M 30135 and evaluation of their emulsifying, antioxidant and antiproliferative activities

Some microorganisms such as yeasts can produce high molecular weight and valuable polymers that known as exopolysaccharides (EPSs). Given the functional properties of yeast exopolysaccharides (EPSs) and a few numbers of studies in this field, the present study was aimed to characterize the EPSs from Rhodotorula minuta (IBRC-M 30135) and to evaluate their emulsifying, antioxidant and antiproliferative activities. R.minuta excreted 1.2 +/- 0.1 g of the EPSs per 1000 ml of fermentation medium. Glucose, mannose and rhamnose were found as main monosaccharides of the EPSs (49, 38 and 13 mol%, respectively) through gas chromatography-mass spectrometry (GC-MS) analysis. In addition, three EPS fractions were obtained with the molecular weights of 356, 500 and 220 kDa. The water retention capacity of the EPSs was 342 +/- 27%. The EPSs exhibited relatively good oil-emulsifying activity and the enhanced synergism between the R.minuta's EPSs and commercially used hydrocolloids (guar gum and sodium alginate) was observed. In vitro, antioxidant activity was investigated against DPPH, hydroxyl and superoxide free radicals. At a concentration of 10 mg/ml, the DPPH, hydroxyl and superoxide free radicals scavenging activities were 21.8 +/- 0.7%, 24.6 +/- 1.4% and 12.1 +/- 0.4%, respectively; and the scavenging activities against all were higher than hyaluronic acid. In addition, the treatment of human breast adenocarcinoma (MCF7) and Madin-Darby Canine Kidney (MDCK) cell lines with 20-1000 mu g/ml of the EPSs caused no significant differences in the cells proliferation (P>0.05). These results indicated the promising potential of the EPSs from R.minuta as non-toxic and biocompatible compounds for using in food, cosmetic and pharmaceutical fields