Ist die Studienwahl abhängig von der besuchten Schule?

Dans cet article, nous tentons d’étudier les différences de choix d’études d’élèves en fin de secondaire en Communauté française de Belgique, en fonction de leurs caractéristiques individuelles (sexe, SES, filière, redoublement), mais aussi en fonction de l’école fréquentée (effet de l’offre d’enseignement et du recrutement social de l’école). L’analyse multiniveau montre que les projets d’études supérieures ne sont pas seulement indépendants des caractéristiques de l’individu mais également, dans certains cas, de l’établissement dans lequel les élèves sont scolarisés en fin de secondaire après contrôle des caractéristiques individuelles. En effet, lorsqu’on étudie le choix d’aller à l’université plutôt que non, on constate un effet de la composition sociale de l’établissement. Toutes choses égales par ailleurs, l’offre d’enseignement n’a quant à elle pas d’effet significatif sur les aspirations d’études. (DIPF/Orig.)In diesem Beitrag wird die Studienwahl von Schülerinnen und Schülern am Ende der Sekundarstufe II im französischsprachigen Teil Belgiens untersucht. Dabei werden sowohl individuelle Merkmale der Schüler/innen (Geschlecht, sozioökonomischer Hintergrund, Klassenwiederholung) als auch Merkmale der besuchten Schule (Unterrichtsangebot, soziale Herkunft der Schüler/innen) zur Erklärung der Studienwahl herangezogen. Die Mehrebenenanalyse zeigt zwar, dass die Studienvorhaben nicht unabhängig von den individuellen Merkmalen sind. Sie zeigt aber zusätzlich, dass – nach Kontrolle der individuellen Merkmale – auch die Institution, die die Schüler/innen am Ende der Sekundarstufe II besuchen, in einigen Fällen eine Rolle spielt. Der Entscheid, ob jemand an die Universität geht oder nicht, wird von der sozialen Zusammensetzung der Herkunftsschulen beeinflusst. Das Bildungsangebot der Herkunftsschule alleine hat demgegenüber keinen Einfluss auf die angestrebten Studien. (DIPF/Orig.

Strain Rate and Orientation Dependencies of the Strength of Single Crystalline Copper under Compression

Molecular dynamics (MD) simulations are used to model the compression under uniaxial strain of copper single crystals of different orientations at various temperatures and strain rates. Uniaxial strain is used because of the close resemblance of the resulting stress state with the one behind a shock front, while allowing a control of parameters such as strain rate and temperature to better understand the behavior under complex dynamic shock conditions. Our simulations show that for most orientations, the yield strength of the sample is increased with increasing strain rate. This yield strength is also dependent on the orientation of the sample, but less dependent on temperature. We find three regimes for the atomistic behavior around the yield: homogeneous dislocation nucleation, appearance of disordered atoms followed by dislocation nucleation, and amorphization. Finally, we show that a criterion solely based on a critical resolved shear and normal stress is insufficient at these strain rates to determine slip on a system

Signalisation par les récepteurs des œstrogènes : mécanismes de reconnaissance de l’ADN et nouvelles approches pharmacologiques d’inhibition

Malgré les progrès des traitements des cancers du sein, ceux-ci demeurent la seconde cause de mortalité par cancer au Canada. Parmi les gènes associés aux cancers du sein, le récepteur des œstrogènes ERα est exprimé dans plus de 70% des tumeurs mammaires, qui prolifèrent en réponse aux œstrogènes, faisant de lui une cible de choix. ERα est un facteur de transcription ligand-dépendant, liant des éléments de réponse PuGGTCAnnnTGACCPy. Afin d’examiner la capacité des récepteurs nucléaires à reconnaitre de nouveaux motifs ADN, des mutants aux capacités de liaison modifiées ont été générés. Parmi les quatre résidus interagissant avec l’ADN, R211 ne peut pas être modifiée sans perdre complètement la liaison du récepteur à l’ADN. Néanmoins, les mutations combinées de plusieurs acides aminés contactant les bases de l’ERE ont généré des récepteurs capables de reconnaitre de nouveaux motifs, tout en conservant des niveaux de transactivation efficaces. L’utilisation potentielle des récepteurs nucléaires comme outils de thérapie génique hormono-dépendant, repose sur la prédiction des motifs de liaison efficaces. Étant donné son importance dans la carcinogenèse mammaire, ERα est une cible cruciale des thérapies anti-néoplastiques. L’anti-œstrogène total, ICI, induit la dégradation de ERα et l’arrêt de la croissance des cellules tumorales mammaires ERα-positives. De plus, la nouvelle drogue anti-tumorale HDACi, SAHA, module la voie de signalisation des œstrogènes et possède des propriétés prometteuses en association avec d’autres traitements anti-tumoraux. En effet, le co-traitement ICI et SAHA a un impact synergique sur l’inhibition de la prolifération des cellules mammaires tumorales ERα-positives. Cette synergie repose sur la coopération des effets de ICI et SAHA pour réduire les niveaux protéiques de ERα et bloquer la progression du cycle cellulaire via la modulation de la transcription des gènes cibles des œstrogènes. En fait, les fortes doses de HDACis masquent rapidement et complètement la signalisation transcriptionnelle des œstrogènes. De plus, les gènes cibles primaires des œstrogènes, contenant des EREs, présentent la même régulation transcriptionnelle en réponse aux fortes doses de SAHA ou du co-traitement, avec des doses utilisables en clinique de ICI et SAHA. En fait, ICI mime l’impact des fortes doses de SAHA, en dégradant ERα, potentialisant ainsi la répression de la transcription ERE-dépendante par SAHA. Finalement, la synergie des effets de ICI et SAHA pourrait augmenter l’efficacité des traitements des tumeurs mammaires.Despite the progress in breast cancer therapy, it is still the second cause of death by cancer in the western world. The estrogen receptor alpha (ER) is expressed in more than 70% of breast tumors, which then proliferate in response to E2 stimulation. ERα is a ligand-dependant transcription factor, which binds to palindromic response elements composed of PuGGTCA motifs. In order to examine the capacity of nuclear receptors to be tailored to recognize novel DNA motifs, rational design of ERα mutants with altered binding specificity were achieved. Of the four amino-acids interacting with DNA, R211 cannot be altered to another residu without a complete loss of DNA binding. However, combined mutagenesis of the amino-acids contacting the bases of the ERE generate receptors that recognized a new type of motifs with efficient transcriptional transactivation levels. In order to consider nuclear receptors as potential hormonal-dependent tools for genetic therapy, bio-informatic models predicting DNA binding are needed. Considering its importance in breast carcinogenesis, ERα is a crucial target for anti-neoplastic therapies. The full anti-estrogen ICI provokes ER degradation and ER-positive breast cancer growth arrest. Moreover, the new HDACi anti-tumoral drug, SAHA modulates the estrogen pathway and have promising properties in association with other anti-neoplastic drugs. In this context, our goal was to determine the effects of the ICI and SAHA combined treatment on breast cancer cell proliferation. The combined treatment has a synergistic impact on inhibiting ERα-positive breast cancer cell growth. It occurs through the cooperation of ICI and SAHA to reduce ER protein level, and to block the cell cycle progression through the transcriptional regulation of E2-target genes. Actually, high doses of HDACis completely and rapidly mask E2-transcriptional signaling. Moreover, primary E2-target genes show the same transcriptional regulation in presence of high doses of SAHA as with the co-treatment, using clinically feasible doses of ICI and SAHA. In fact, ICI mimics the impact of high doses of SAHA through ER degradation, and then potentiate the repressional effect of low doses of SAHA on ERE-dependant transcription. Finally, the synergy of ICI and SAHA might increase the potency of breast cancer therapy

Ghrelin in Female and Male Reproduction

Ghrelin and one of its functional receptors, GHS-R1a (Growth Hormone Secretagogue Receptor 1a), were firstly studied about 15 years. Ghrelin is a multifunctional peptide hormone that affects several biological functions including food intake, glucose release, cell proliferation… Ghrelin and GHS-R1a are expressed in key cells of both male and female reproductive organs in several species including fishes, birds, and mammals suggesting a well-conserved signal through the evolution and a role in the control of fertility. Ghrelin could be a component of the complex series of nutrient sensors such as adipokines, and nuclear receptors, which regulate reproduction in function of the energy stores. The objective of this paper was to report the available information about the ghrelin system and its role at the level of the hypothalamic-pituitary-gonadal axis in both sexes

Motion of a spherical capsule in simple shear flow: influence of the bending resistance

National audienceWe simulate the motion of an initially spherical capsule in a simple shear flow in order to determine the influence of the bending resistance on wrinkle formation on the membrane. We use a numerical method coupling a nonlinear shell finite element method for the capsule wall mechanics with a boundary integral method to solve the Stokes equation. The capsule wall is discretized with MITC linear triangular shell finite elements. We find that, at low flow strength, buckling occurs in the central region of the capsule. The number of wrinkles on the membrane decreases with the bending stiffness and above a critical value, wrinkles no longer form. For thickness to radius ratios below 5%, the bending stiffness does not have any significant effect on the overall capsule motion and deformation. The mean capsule shape is identical whether the wall is modeled as a shell or a two-dimensional membrane, which shows that the dynamics of thin capsules is mainly governed by shear elasticity and membrane effects

Coupling boundary integral and shell finite element methods to study the fluid structure interactions of a microcapsule in a simple shear flow

International audienceWe simulate the motion of an initially spherical capsule in a simple shear flow in order to determine the influence of the bending resistance on the formation of wrinkles on the membrane. The fluid structure interactions are obtained numerically coupling a boundary integral method to solve for the Stokes equation with a nonlinear finite element method for the capsule wall mechanics. The capsule wall is discretized with MITC linear triangular shell finite elements. We find that, at low flow strength, buckling occurs in the central region of the capsule. The number of wrinkles on the membrane decreases with the bending stiffness and, above a critical value, wrinkles no longer form. For thickness to radius ratios below 5%, the bending stiffness does not have any significant effect on the overall capsule motion and deformation. The mean capsule shape is identical whether the wall is modeled as a shell or a two-dimensional membrane, which shows that the dynamics of thin capsules is mainly governed by shear elasticity and membrane effects

Biochars from various biomass types as anodes for sodium-ion batteries

Until now, the applications targeted for biochars have mostly been focused in the field of energy, as combustion fuel, or of agronomy, as soil amendment. However, high-added value materials in the field of electrochemistry are now more and more mentioned as promising applications to investigate (Deng et al. 2016). At the moment, one major topic in electrochemistry is the development of alternative to lithium-ion battery in order to solve the issue of lithium supply. One of the most mature options is sodium-ion battery (Wang et al. 2016). In such battery, anode is generally made up of hard carbon, that has surface area below 10 m2.g-1 and subnanometric pores. Please click on the file below for full content of the abstract

Effect of adiponectin on bovine granulosa cell steroidogenesis, oocyte maturation and embryo development

<p>Abstract</p> <p>Background</p> <p>Adiponectin is an adipokine, mainly produced by adipose tissue. It regulates several reproductive processes. The protein expression of the adiponectin system (adiponectin, its receptors, AdipoR1 and AdipoR2 and the APPL1 adaptor) in bovine ovary and its role on ovarian cells and embryo, remain however to be determined.</p> <p>Methods</p> <p>Here, we identified the adiponectin system in bovine ovarian cells and embryo using RT-PCR, immunoblotting and immunohistochemistry. Furthermore, we investigated in vitro the effects of recombinant human adiponectin (10 micro g/mL) on proliferation of granulosa cells (GC) measured by [3H] thymidine incorporation, progesterone and estradiol secretions measured by radioimmunoassay in the culture medium of GC, nuclear oocyte maturation and early embryo development.</p> <p>Results</p> <p>We show that the mRNAs and proteins for the adiponectin system are present in bovine ovary (small and large follicles and corpus luteum) and embryo. Adiponectin, AdipoR1 and AdipoR2 were more precisely localized in oocyte, GC and theca cells. Adiponectin increased IGF-1 10(-8) M-induced GC proliferation (P < 0.01) but not basal or insulin 10(-8) M-induced proliferation. Additionally, adiponectin decreased insulin 10(-8) M-induced, but not basal or IGF-1 10(-8) M-induced secretions of progesterone (P < 0.01) and estradiol (P < 0.05) by GC. This decrease in insulin-induced steroidogenesis was associated with a decrease in ERK1/2 MAPK phosphorylation in GC pre-treated with adiponectin. Finally, addition of adiponectin during in vitro maturation affected neither the percentage of oocyte in metaphase-II nor 48-h cleavage and blastocyst day 8 rates.</p> <p>Conclusions</p> <p>In bovine species, adiponectin decreased insulin-induced steroidogenesis and increased IGF-1-induced proliferation of cultured GC through a potential involvement of ERK1/2 MAPK pathway, whereas it did not modify oocyte maturation and embryo development in vitro.</p