Vérité et mensonge dans Un Amour de Swann de Marcel Proust

Séance solennelle du 14 décembre 201

Age-dependent role of steroids in the regulation of growth of the hen follicular wall

<p>Abstract</p> <p>Background</p> <p>The ovaries are the primary targets of senescence effects in mammalian and avian species. In the present study, relationships between reproductive aging, sex steroids and the growth pattern of the pre-ovulatory follicle wall were investigated using young hens with long clutch (YLC), old hens with long clutch (OLC), old hens with short clutch (OSC), and old hens with interrupted long clutch (OILC).</p> <p>Methods</p> <p>Experiment 1: Hens were sacrificed 1.5 and 14.5 h after ovulation. Experiment 2: YLC and OILC hens were sacrificed 3.5 h after treatments with LH and/or aminoglutethimide (AG), an inhibitor of steroid synthesis. Volumes of pre-ovulatory follicles (F1-F5) and plasma concentrations of ovarian steroids were determined. Experiment 3: Granulosa and theca cells from F3 follicles of OSC and/or YLC hens were exposed in vitro to estradiol-17beta (E₂), testosterone (T) and LH and the proliferative activity of the cells was examined using CellTiter 96 Aqueous One Solution Assay.</p> <p>Results</p> <p>In YLC and OLC groups, the total volume of F1-F5 follicles rose between 1.5 and 14.5 h after ovulation (P < 0.01), negatively correlating with the plasma level of E₂(P < 0.01). There was no growth of pre-ovulatory follicles in the middle of the ovulatory cycle in the OSC group, with a positive correlation being present between E₂and the follicular volume (P < 0.05). In young hens, AG caused a rise in the total follicular volume. This rise was associated with a fall in E₂(r = -0.54, P < 0.05). E₂enhanced proliferation of granulosa cells from YLC and OSC groups. The proliferative activity of granulosa and theca cells of YLC hens depended on the interaction between T and LH (P < 0.01).</p> <p>Conclusions</p> <p>These data indicate for the first time that the growth pattern of pre-ovulatory follicles during the ovulatory cycle changes in the course of reproductive aging. E₂seems to play a dual role in this adjustment; it stimulates the growth of the follicular wall in reproductive aged hens, whereas it may inhibit this process in young birds. T and LH are apparently involved in the growth regulation during the pre-ovulatory surge in young hens.</p

La formation des doctorants à l'information scientifique et technique

La formation des doctorants aux problématiques de l'information scientifique et technique représente un enjeu particulièrement sensible pour l'enseignement supérieur et la recherche en France. Doublement affectée par de profondes transformations institutionnelles ainsi que par l'évolution accélérée des technologies numériques, la culture de l'information scientifique demeure l'un des piliers fondamentaux de la recherche et un élément incontournable dans la mise en œuvre d'une politique éclairée. La plupart des domaines d'activité du chercheur sont concernés : l'investigation, la propriété intellectuelle, la recherche documentaire, l'écriture scientifique, la publication, la communication scientifique, l'évaluation, les évolutions et les opportunités offertes par les outils numériques, la vulgarisation scientifique… Cet ouvrage se propose de poser quelques jalons afin d'alimenter la réflexion des divers protagonistes, universitaires, documentalistes, bibliothécaires, qui interviennent auprès du doctorant pour l'informer ou le guider tout au long de son parcours : quels seraient les attentes des doctorants et les besoins du monde académique ? Quelles connaissances et compétences les formateurs ont-ils à mobiliser ? Quels enseignements tirer des expériences et dispositifs mis en place ? Autant de questions pour approcher une thématique à la morphologie complexe. Le débat qu'elles suscitent met en lumière un bilan riche en interrogations et fécond pour l'avenir

Search for top squark pair production in pp collisions at root s=13 TeV using single lepton events

Peer reviewe

Search for direct production of supersymmetric partners of the top quark in the all-jets final state in proton-proton collisions at root s=13 TeV

Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

Search for direct production of supersymmetric partners of the top quark in the all-jets final state in proton-proton collisions at √s = 13 TeV

A search for direct production of top squark pairs in events with jets and large transverse momentum imbalance is presented. The data are based on proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector in 2016 at the CERN LHC, and correspond to an integrated luminosity of 35.9 fb−1. The search considers a variety of R-parity conserving supersymmetric models, including ones for which the top squark and neutralino masses are nearly degenerate. Specialized jet reconstruction tools are developed to exploit the unique characteristics of the signal topologies. With no significant excess of events observed above the standard model expectations, upper limits are set on the direct top squark pair production cross section in the context of simplified supersymmetric models for various decay hypotheses. Models with larger differences in mass between the top squark and neutralino are probed for masses up to 1040 and 500 GeV, respectively, whereas models with a more compressed mass hierarchy are probed up to 660 and 610 GeV, respectively. The smallest mass difference probed is for masses near to 550 and 540 GeV, respectively