Polyploidization in liver tissue.

International audiencePolyploidy (alias whole genome amplification) refers to organisms containing more than two basic sets of chromosomes. Polyploidy was first observed in plants more than a century ago, and it is known that such processes occur in many eukaryotes under a variety of circumstances. In mammals, the development of polyploid cells can contribute to tissue differentiation and, therefore, possibly a gain of function; alternately, it can be associated with development of disease, such as cancer. Polyploidy can occur because of cell fusion or abnormal cell division (endoreplication, mitotic slippage, or cytokinesis failure). Polyploidy is a common characteristic of the mammalian liver. Polyploidization occurs mainly during liver development, but also in adults with increasing age or because of cellular stress (eg, surgical resection, toxic exposure, or viral infections). This review will explore the mechanisms that lead to the development of polyploid cells, our current state of understanding of how polyploidization is regulated during liver growth, and its consequence on liver function

Àsìkò : On the Future of Artistic and Curatorial Pedagogies in Africa

Àsìkò s’empare du mot qui signifie « temps » en yoruba pour désigner un ensemble de pratiques artistiques et curatoriales en perpétuelle évolution. Inscrites dans la durée, ces pratiques captent le passage du temps et respirent une forme d’aller-retour avec leur milieu : le local est vécu en interconnexion avec une conscience élargie du monde de l’art contemporain, avec les aléas politiques globaux et avec l’histoire d’un continent. Àsìkò est un programme de workshops annuels tenus dans plusi..

Le point sur la nécrose hématopoiétique infectieuse et la septicémie hémorragique virale des salmonidés

La Nécrose Hématopoïétique Infectieuse (N.H.I.) et la Septicémie Hémorragique Virale (S.H.V.) sont deux viroses qui infectent les salmonidés. Nous nous y intéressons ici en tant que fléaux de la salmoniculture. L'épidémiologie dans le milieu naturel n'est pas totalement élucidée à ce jour. Déclarées maladies légalement reconnues contagieuses en France depuis 1985, leur déclaration est obligatoire. Des qualifications ont été mises en place pour les piscicultures afin de gérer les risques liés aux échanges. Des mesures de police sanitaire y sont associées. Cependant, les effets de ces mesures réglementaires n'apparaîtront pas rapidement. Un vaccin serait donc salvateur. Le virus impliqués appartiennent à la famille des Rhabdoviridae, genre Novirhabdovirus. Il exposent à leur surface une glycoprotéine très immunogène et donc d'intérêt majeur dans la recherche d'un vaccin. Différentes équipes travaillent en parallèle pour découvrir de nouvelles pistes dans la vaccination. Le meilleur compromis entre la protection engendrée et les exigences techniques et sanitaires a été obtenu avec les vaccins génétiques. A ce jour, les différentes voies ont été explorées mais des connaissances plus précises sur les poissons et leur système de défense éclaireraient les premières avancées

Trésors de l'Islam en Afrique : de Tombouctou à Zanzibar

L’exposition, Trésors de l'Islam en Afrique, montrait des œuvres d’art contemporain à côté d’objets culturels, traces matérielles d’une histoire mouvementée : manuscrits, talismans, objets régaliens, photographies documentaires. Les textes du catalogue constituent des introductions aux questions détaillées du vaste sujet de la diffusion des Islams à travers le Sahara et les interdépendances transsahariennes engendrées : plus de mille ans d’histoire se jouant sur un vaste continent. Ces relati..

Women in Art and Literature Networks : Spinning Webs

Par sa finition le livre évoque la fragilité, la subtilité, quelque chose de peu visible, peu tangible : le réseau est apparenté à la toile d’araignée, un système interconnecté, inter-communicant et paradoxal (p. 1). Suite à une série de publications françaises dédiées à « la création au féminin », les éditrices choisissent ici de traduire les essais vers l’anglais, s’ouvrant ainsi aux polémiques qui peuvent apparaitre entre les deux traditions universitaires quant aux usages d’un corpus théo..

Experimental and numerical study of the hydrodynamics of an isolated bubble in non-Newtonian liquid phase in a thin gap bubble column

International audienceDevelopment of photobioreactors (PBR) for microalgae cultivation is a primary concern, keeping in mind the applicative potential of these photosynthetic microorganisms. For this purpose, optimization of culture parameters and PBRs design are the two possible solutions in order to obtain high volumetric productivities. The thin-gap intensified PBR allows to obtain these performances via an increase of culture concentration for a given illuminated surface. When compared with usual PBRs, the confinement results in a high change of the hydrodynamics and mass transfer[1]. To optimize these production systems, our study focuses on the characterization of local hydrodynamics in a 2D bubble column of 4 mm thickness (FIG. 1). Furthermore, it has been shown that the increase in cell concentration is accompanied by rheological properties modifications of the microalgae suspension. To mimic such high concentration of Chlorella vulgaris cultures which have non-Newtonian shear thinning behaviour at concentrations ranging from 30-40 g/L[2], solutions of Xanthan Gum (XG) and Carboxymethyl cellulose (CMC) are used respectively at the concentrations of 1 g/L and 2 g/L. In order to put forward the effect of the rheological behaviour, demineralized water is also used as a Newtonian fluid. In this preliminary work, the main purpose is to estimate the terminal velocity (V t) of an isolated bubble in this confined column. In fact, if the terminal velocity for an isolated bubble is modified due to wall effects, there will have consequences for hydrodynamics and mass transfer of the whole bubble column: for instance, bubble residence time or gas hold up will be modified[1]. B.Figueroa Espinoza et al. [3] reported the confinement effect for a single clean bubble, pointing out that the drag coefficient widely increases for oscillating bubbles rising in a Hele-shaw cell. The experimental part consists in studying the local hydrodynamics behaviour of isolated bubbles of different diameters for three liquid media: water, CMC and XG solutions. Capillaries tubes, having diameters (d c) of 0.127, 0.264, 0.508, 0.762 or 1.016 mm are used to generate isolated bubbles at different diameter sizes with the help of a low-pressure syringe pump (NEMESYS, GERMANY). Bubble injection is performed 7 cm away from the lateral wall which can be considered sufficient to avoid wall influence on the hydrodynamics of isolated bubble. Bubble size and instantaneous bubble velocity are estimated by a shadowgraphy method using the DANTEC DYNAMICS Shadow Strobe. These measurements are performed at mid height of the column, where bubble terminal velocities have been reached. The experimental terminal velocities for different bubble diameters (d b) in water, CMC and XG liquid media are reported in Table 1 and plotted in FIG. 2(a). Water measurements are also compared to the correlation established by M.Jamialahmadi et al.[4] and the data of R.Clift et al. [5] which concern isolated bubble in pure water in infinite liquid medium (FIG. 2(b)). It is found that for an isolated bubble rising in quiescent liquid, with a diameter lower than 4 mm, the terminal velocity is divided by V t ratio between 1.2 and 1.6 for water. Besides this in non-Newtonian solutions, for lower bubble diameters the terminal velocity is less than water medium and as the bubble diameter increases it becomes constant this phenomena was also experienced by Shahram Amirnia et al.[6]. In parallel to experiments, a numerical study is performed to characterize the behaviour of one single bubble in the confined space between two walls in Newtonian and Non-Newtonian media. Simulations are performed with academic Ansys Fluent 17.2 solver using volume of fluid (VOF) method for interface tracking along with continuum surface Force (CSF) model to treat surface tension. Firstly, mesh independency verification has been performed by 2D and 3D simulations of a 3 mm diameter bubble in infinite medium. These results have been validated with the results of F.Bertola et al.[7](FIG.2(b)). Thereafter the same confined geometry as experimental setup has been adopted to simulate the bubble diameters determined experimentally. Numerical results are reported in FIG. 2(b) and seem to be in good agreement with the experiments results (FIG 2(b))

Traduire comme pratique artistique. Cinq propositions-interfaces Afrique du Sud/monde

En Afrique du Sud la coexistence de multiples langues trouve un écho dans les pratiques d’artistes qui se situent à l’interface entre deux milieux  : Lerato Shadi, Willem Boshoff, Moshekwa Langa, le duo Dorothée Kreutzfeldt/Bettina Malcomess et le collectif Center for Historical Reenactments. Nourri de la critique de la situation post-apartheid, ce travail prend la forme de fictions personnelles, de performances proche des arts vivants ou d’actions furtives réalisées par un artiste-enquêteur dans sa relation à l’historicité des phénomènes linguistiques et sociaux liés au langage.In South Africa the coexistence of multiple languages is felt in the artistic practices, who become like an interface between epistemological spaces. It is the case in the practices of Lerato Shadi, Willem Boshoff, Moshekwa Langa, the duo Dorothée Kreutzfeldt/Bettina Malcomess and the collective The Center for Historical Reenactments. Nourished by post apartheid critique these works take on the form of a personal fiction, performance close to actionism or “actions furtives” performed by an artist-researcher in his relationship with the historicity of linguistic and social phenomena linked to language