Étude de physique au-delà du Modèle Standard dans les désintégrations B→πK

Ce mémoire s'intéresse aux quatre désintégrations B→πK: B⁺→π⁺K⁰, B⁺→π⁰K⁺, Bd⁰→π⁻K⁺ et Bd⁰→π⁰K⁰. Celles-ci sont intéressantes à étudier puisqu'elles sont reliées à la violation CP dans le secteur des quarks. À l'aide d'ajustements, des données expérimentales les plus récentes et de l'approche diagrammatique, ce projet analyse ces désintégrations pour quantifier le désaccord avec le Modèle Standard, et déterminer si des modèles de nouvelle physique peuvent réduire ce désaccord. Les résultats obtenus montrent que le rapport |C'|/|T'| est central pour déterminer l'état du désaccord avec le Modèle Standard. Il s'agit du rapport entre les grandeurs des amplitudes de deux diagrammes intervenant dans les désitnégrations B→πK. Ces diagrammes sont le diagramme de type arbre avec suppression de couleur (C') et celui sans suppression de couleur (T'). Si ce rapport est élevé (∼ 0.5), le Modèle Standard peut expliquer les désintégrations. Ce n'est pas le cas s'il est faible (∼ 0.2). Dans ce cas, des modèles de nouvelle physique peuvent améliorer la situation, sans toutefois expliquer totalement le désaccord. C'est le cas du Z', une particule qui peut causer une transition b̄→s̄ au niveau des arbres. Pour qu'un modèle de Z' puisse réduire le désaccord dans les désintégrations B→πK, le Z' doit se coupler à ūRuR et/ou d̄RdR et le couplage ne doit pas être le même dans les deux cas. Plusieurs modèles permettent que le Z' se couple à b̄→s̄μ⁺μ⁻, ceux-ci peuvent expliquer plusieurs anomalies reliées à cette transition. Pour la moitié de ces modèles, le Z' respecte également les conditions nécessaires pour réduire le désaccord dans B→πK. Des modèles impliquant un diquark, une particule pouvant se coupler à deux quarks de même chiralité ont aussi été considérés. Les résultats obtenus montrent qu'un diquark étant un sextet de couleur et se couplant à uⁱL,RdʲL,R peut également réduire le désaccord dans les désintégrations B→πK.This thesis deals with the four B→πK decays: B⁺→π⁺K⁰, B⁺→π⁰K⁺, Bd⁰→π⁻K⁺ and Bd⁰→π⁰K⁰. These are interesting to study since they are related to CP violation in the quark sector. Using fits, the latest experimental results on these decays and the diagrammatic approach, this project measures the disagreement with the Standard Model and determines whether new physics models can reduce this disagreement. The results obtained show that the ratio |C'|/|T'| is essential to determine the state of the disagreement with the Standard Model. This is a ratio between the magnitudes of two diagrams contributing the B→πK decays. These diagrams are the color suppressed (C') and color allowed (T') tree diagrams. If this ratio is high (∼ 0.5), the Standard Model can explain the decays. If it is low (∼ 0.2), it cannot. In this case, it was found that new physics models can improve on the Standard Model, whithout however fully explaining the disagreement. This is the case for a Z', a particule that can cause a transition b̄→s̄ at tree level. For Z' models to improve on the Standard Model, the Z' must couple to ūRuR and/or d̄RdR, and the coupling in each of these cases must be different. In some models, the Z' can couple to b̄→s̄μ⁺μ⁻. These models can explain many anomalies observed in this transition. For half of these models, the Z' also has the requirements needed to reduce the disagreement in the B→πK decays. Models involving a diquark, a particle that can couple to 2 quarks of the same chirality were also considered. It was found that a color sextet diquark that couples to uⁱL,RdʲL,R can reduce the disagreement found in the B→πK decays

ARQUEOLOGIA E VALORIZAÇÃO DA ILHA SAINT-BARNABÉ (RIMOUSKI, QUÉBEC): DA MATERIALIZAÇÃO DE UM MITO À PERFORMANCE ARQUEOLÓGICA

This article offers reflections on the experience of a long-term archaeological investigation in an academic context and is interested in the evolution of the objectives, expectations, and interests of its various actors. The project combined research, education, and development, seeking a balance among these three dimensions of the project that fed each other. This balance allowed a place for the interests of each of the actors: those of the university professor-researchers and students, those of the local municipality and its tourism promotion agency, and those of the general public. Over time, the education mission of the project has taken on a more important role and the development has gradually taken the form of an archaeological performance. The authors question the long-term viability of this type of development.Este artigo estuda a evolução dos objetivos, das expectativas e dos interesses dos diferentes atores de uma experiência de intervenção arqueológica de longo prazo realizada no contexto universitário. A intervenção conciliava pesquisa, ensino e valorização, buscando equilibrar estas três dimensões que alimentavam reciprocamente. Este equilíbrio permitiu responder aos interesses de cada um dos atores: os da universidade, dos professores-pesquisadores e dos estudantes, os da municipalidade e do seu órgão de promoção turística, e os do publico em geral. Ao longo do tempo, o ensino assumiu uma importância cada vez maior e a valorização progressivamente assumiu a forma de uma performance arqueológica. Os autores questionam-se sobre a viabilidade à longo prazo deste tipo de valorização.Cet article propose un retour sur une expérience d’intervention archéologique de longue durée en contexte universitaire et s’intéresse à l’évolution des objectifs, des attentes et des intérêts de ses différents acteurs. L’intervention conciliait recherche, enseignement et mise en valeur, cherchant un équilibre entre ces trois dimensions qui se nourrissaient mutuellement. Cet équilibre permettait de répondre aux intérêts de chacun des acteurs : ceux de l’université, les professeurs-chercheurs et des étudiants, ceux de la municipalité et de son organisme de promotion touristique, ceux du public en général. Au fil du temps, l’enseignement a pris une dimension de plus en plus affirmée et la mise en valeur a graduellement pris la forme d’une performance archéologique. Les auteurs s’interrogent sur la viabilité à long terme d’une telle forme de mise en valeur

The translational repressor 4E-BP mediates hypoxia-induced defects in myotome cells.

International audienceCell growth, proliferation, differentiation and survival are influenced by the availability of oxygen. The effect of hypoxia on embryonic cells and the underlying molecular mechanisms to maintain cellular viability are still poorly understood. In this study, we show that hypoxia during Xenopus embryogenesis rapidly leads to a significant developmental delay and to cell apoptosis after prolonged exposure. We provide strong evidence that hypoxia does not affect somitogenesis but affects the number of mitotic cells and muscle-specific protein accumulation in somites, without interfering with the expression of MyoD and MRF4 transcription factors. We also demonstrate that hypoxia reversibly decreases Akt phosphorylation and increases the total amount of the translational repressor 4E-BP, in combination with an increase of the 4E-BP associated with eIF4E. Interestingly, the inhibition of PI3-kinase or mTOR, with LY29002 or rapamycin, respectively, triggers the 4E-BP accumulation in Xenopus embryos. Finally, the overexpression of the non-phosphorylatable 4E-BP protein induces, similar to hypoxia, a decrease in mitotic cells and a decrease in muscle-specific protein accumulation in somites. Taken together, our studies suggest that 4E-BP plays a central role under hypoxia in promoting the cap-independent translation at the expense of cap-dependent translation and triggers specific defects in muscle development

Byllis (Albanie), campagne 2007 : le quartier épiscopal, la basilique E et les carrières

La mission franco-albanaise à Byllis est subventionnée à parité par l’École française d’Athènes et le ministère des Affaires étrangères. L’année 2007 représentait la neuvième campagne sur le site ; elle a duré quatre semaines, du 8 mai au 2 juin . La mission de 2007 avait pour principal objectif la poursuite de la fouille du quartier épiscopal, sous la direction de N. Beaudry. On a également poursuivi l’étude du matériel découvert (céramique et métaux). L’étude d’une carrière de la ville a ét..

Le quartier épiscopal de Byllis (Albanie). Les campagnes de fouilles 2011-2012

Désertée à la fin du vie-début du viie siècle devant la pression continue des incursions avaro-slaves, la ville de Byllis, fondée à l’époque hellénistique au sommet d’une colline calcaire dominant la rive droite de la Vjosa (Aôos), constitue un observatoire privilégié des bouleversements que connaît le tissu urbain aux ve-vie siècles apr. J.-C. Siège épiscopal indépendant depuis le milieu du ve siècle, c’était au vie siècle l’une des villes les plus importantes de la province d’Epirus Nova. C..

Polycrystalline CdSeTe/CdTe absorber cells with 28 mA/cm2 short-circuit current

An 800-nm CdSeTe layer was added to the CdTe absorber used in high-efficiency CdTe cells to increase the current and produce an increase in efficiency. The CdSeTe layer employed had a band gap near 1.41 eV, compared to 1.5 eV for CdTe. This lower band-gap allowed a current increase from approximately 26 to over 28 mA/cm2. Voltage same as earlier demonstrated high efficiency CdTe-only device was maintained. The fill-factor was not significantly affected. Improving the short-circuit current and maintaining the open-circuit voltage lead to device efficiency over 19%. QE implied that the approximately half the current was generated in the CdSeTe layer and half in the CdTe. Cross-section STEM and EDS showed good grain structure throughout and diffusion of Se into the CdTe layer was observed. To the best of authors’ knowledge this is the highest efficiency polycrystalline CdTe photovoltaic device demonstrated amongst universities and national labs

Effect of CdCl2 passivation treatment on microstructure and performance of CdSeTe/CdTe thin-film photovoltaic devices

The effects of the CdCl2passivation treatment on thin-film CdTe photovoltaic films and devices have been extensively studied. Recently, with an addition of CdSeTe layer at the front of the absorber layer, device conversion efficiencies in excess of 19% have been demonstrated. The effects of the CdCl2passivation treatment for devices using CdSeTe has not been studied previously. This is the first reported study of the effect of the treatment on the microstructure of the CdSeTe /CdTe absorber. The device efficiency is < 1% for the as-deposited device but this is dramatically increased by the CdCl2treatment. Using Scanning Transmission Electron Microscopy (STEM), we show that the CdCl2passivation of CdSeTe/CdTe films results in the removal of high densities of stacking faults, increase in grain size and reorientation of grains. The CdCl2treatment leads to grading of the absorber CdSeTe/CdTe films by diffusion of Se between the CdSeTe and CdTe regions. Chlorine decorates the CdSeTe and CdTe grain boundaries leading to their passivation. Direct evidence for these effects is presented using STEM and Energy Dispersive X-ray Analysis (EDX) on device cross-sections prepared using focused ion beam etching. The grading of the Se in the device is quantified using EDX line scans. The comparison of CdSeTe/CdTe device microstructure and composition before and after the CdCl2treatment provides insights into the important effects of the process and points the way to further improvements that can be made

The spotted gar genome illuminates vertebrate evolution and facilitates human-teleost comparisons

To connect human biology to fish biomedical models, we sequenced the genome of spotted gar (Lepisosteus oculatus), whose lineage diverged from teleosts before teleost genome duplication (TGD). The slowly evolving gar genome has conserved in content and size many entire chromosomes from bony vertebrate ancestors. Gar bridges teleosts to tetrapods by illuminating the evolution of immunity, mineralization and development (mediated, for example, by Hox, ParaHox and microRNA genes). Numerous conserved noncoding elements (CNEs; often cis regulatory) undetectable in direct human-teleost comparisons become apparent using gar: functional studies uncovered conserved roles for such cryptic CNEs, facilitating annotation of sequences identified in human genome-wide association studies. Transcriptomic analyses showed that the sums of expression domains and expression levels for duplicated teleost genes often approximate the patterns and levels of expression for gar genes, consistent with subfunctionalization. The gar genome provides a resource for understanding evolution after genome duplication, the origin of vertebrate genomes and the function of human regulatory sequences