Usages et représentations de la punition : étude de cas au sein d’un lycée général et technologique de la proche banlieue toulousaine

La question que nous nous posons, de manière primordiale, est celle des finalités de la punition et du rapport aux normes scolaires entretenu par les enseignants. Quelles sont les stratégies mises en place pour punir moins ? Pour punir mieux ? Pour éviter de punir ? Et plus globalement : comment la punition s’inscrit-elle dans le cadre de la gestion de la classe par l’enseignant ?Pour répondre à ces questions le choix a été fait de privilégier une approche dite «pragmatique» en sociologie.Afin de mieux saisir les fonctions et finalités des punitions dans les lycées aujourd’hui et pour mieux cerner les différentes configurations d’assujettissement pensées par les enseignants, nous allons nous pencher sur la gestion de classe dans le cadre d’un style d’enseignement particulier, sur les modalités d’intervention qui sont privilégiées par les acteurs, puis dans un second temps il sera question de la punition telle que se la représentent les enquêtés, en pointant aussi ses limites et son caractère potentiellement contre-productif

Convergence in law in the second Wiener/Wigner chaos

Let L be the class of limiting laws associated with sequences in the second Wiener chaos. We exhibit a large subset L_0 of L satisfying that, for any F_infinity in L_0, the convergence of only a finite number of cumulants suffices to imply the convergence in law of any sequence in the second Wiener chaos to F_infinity. This result is in the spirit of the seminal paper by Nualart and Peccati, in which the authors discovered the surprising fact that convergence in law for sequences of multiple Wiener-It\^o integrals to the Gaussian is equivalent to convergence of just the fourth cumulant. Also, we offer analogues of this result in the case of free Brownian motion and double Wigner integrals, in the context of free probability.Comment: 14 pages. This version corrects an error which, unfortunately, appears in the published version in EC

Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion

Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found >2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics—similar to those associated with modern stratospheric ozone depletion over Antarctica—plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka

Candidate genes revealed by a genome scan for mosquito resistance to a bacterial insecticide: sequence and gene expression variations

<p>Abstract</p> <p>Background</p> <p>Genome scans are becoming an increasingly popular approach to study the genetic basis of adaptation and speciation, but on their own, they are often helpless at identifying the specific gene(s) or mutation(s) targeted by selection. This shortcoming is hopefully bound to disappear in the near future, thanks to the wealth of new genomic resources that are currently being developed for many species. In this article, we provide a foretaste of this exciting new era by conducting a genome scan in the mosquito <it>Aedes aegypti </it>with the aim to look for candidate genes involved in resistance to <it>Bacillus thuringiensis </it>subsp. <it>israelensis </it>(<it>Bti</it>) insecticidal toxins.</p> <p>Results</p> <p>The genome of a <it>Bti</it>-resistant and a <it>Bti</it>-susceptible strains was surveyed using about 500 MITE-based molecular markers, and the loci showing the highest inter-strain genetic differentiation were sequenced and mapped on the <it>Aedes aegypti </it>genome sequence. Several good candidate genes for <it>Bti</it>-resistance were identified in the vicinity of these highly differentiated markers. Two of them, coding for a cadherin and a leucine aminopeptidase, were further examined at the sequence and gene expression levels. In the resistant strain, the cadherin gene displayed patterns of nucleotide polymorphisms consistent with the action of positive selection (e.g. an excess of high compared to intermediate frequency mutations), as well as a significant under-expression compared to the susceptible strain.</p> <p>Conclusion</p> <p>Both sequence and gene expression analyses agree to suggest a role for positive selection in the evolution of this cadherin gene in the resistant strain. However, it is unlikely that resistance to <it>Bti </it>is conferred by this gene alone, and further investigation will be needed to characterize other genes significantly associated with <it>Bti </it>resistance in <it>Ae. aegypti</it>. Beyond these results, this article illustrates how genome scans can build on the body of new genomic information (here, full genome sequence and MITE characterization) to finally hold their promises and help pinpoint candidate genes for adaptation and speciation.</p

Modélisation du canal de propagation Air-Sol-Air appliqué aux Radioaltimètres

National audienceUne nouvelle approche pour l'étude de la propagation air-sol-air dans le contexte aéronautique est proposée dans cet article. L'élaboration d'un simulateur à base de fonctions de distribution de réflexion bidirectionnelle destiné à la caractérisation d'équipements de radionavigation aéronautique est détaillée et l'étude du contexte de développement du simulateur, le principe de calcul électromagnétique déployé et les premiers résultats obtenus sont abordés

Small scale structure in diffuse molecular gas from repeated FUSE and visible spectra of HD 34078

We present preliminary results from an ongoing program devoted to a study of small scale structure in the spatial distribution of molecular gas. Our work is based on multi-epoch FUSE and visible observations of HD34078. A detailed comparison of H2, CH and CH+ absorption lines is performed. No short term variations are seen (except for highly excited H2) but long-term changes in N(CH) are clearly detected when comparing our data to spectra taken about 10 years ago.Comment: 4 pages, 2 figures, To appear in the Proceedings of the XVII IAP Colloquium "Gaseous Matter in Galaxies and Intergalactic Space

A MITE-based genotyping method to reveal hundreds of DNA polymorphisms in an animal genome after a few generations of artificial selection

<p>Abstract</p> <p>Background</p> <p>For most organisms, developing hundreds of genetic markers spanning the whole genome still requires excessive if not unrealistic efforts. In this context, there is an obvious need for methodologies allowing the low-cost, fast and high-throughput genotyping of virtually any species, such as the Diversity Arrays Technology (DArT). One of the crucial steps of the DArT technique is the genome complexity reduction, which allows obtaining a genomic representation characteristic of the studied DNA sample and necessary for subsequent genotyping. In this article, using the mosquito <it>Aedes aegypti </it>as a study model, we describe a new genome complexity reduction method taking advantage of the abundance of miniature inverted repeat transposable elements (MITEs) in the genome of this species.</p> <p>Results</p> <p><it>Ae. aegypti </it>genomic representations were produced following a two-step procedure: (1) restriction digestion of the genomic DNA and simultaneous ligation of a specific adaptor to compatible ends, and (2) amplification of restriction fragments containing a particular MITE element called <it>Pony </it>using two primers, one annealing to the adaptor sequence and one annealing to a conserved sequence motif of the <it>Pony </it>element. Using this protocol, we constructed a library comprising more than 6,000 DArT clones, of which at least 5.70% were highly reliable polymorphic markers for two closely related mosquito strains separated by only a few generations of artificial selection. Within this dataset, linkage disequilibrium was low, and marker redundancy was evaluated at 2.86% only. Most of the detected genetic variability was observed between the two studied mosquito strains, but individuals of the same strain could still be clearly distinguished.</p> <p>Conclusion</p> <p>The new complexity reduction method was particularly efficient to reveal genetic polymorphisms in <it>Ae. egypti</it>. Overall, our results testify of the flexibility of the DArT genotyping technique and open new prospects as regards its application to a wider range of species, including animals which have been refractory to it so far. DArT has also a role to play in the current burst of whole-genome scans carried out in various organisms, which track signatures of selection in order to unravel the basis of genetic adaptation.</p

Experimental determination of carbonate-associated sulfate δ^(34)S in planktonic foraminifera shells

Understanding the coupling of oxygen, carbon, and sulfur cycles in the past is critical for reconstructing the history of biogeochemical cycles, paleoclimatic variations, and oceanic chemistry. The abundance of sulfur isotopes (δ^(34)S) in sulfate from ancient marine carbonates, or carbonate-associated sulfate (CAS), is commonly used, along with other archives (mainly evaporites and barite), to estimate the δ^(34)S of seawater throughout Earth history. Analyses of CAS from hand-picked foraminifera are potentially valuable because this group of organisms is used in numerous paleoceanographic studies. They could provide coupled, high-resolution records of δ^(13)C, δ^(18)O, and δ^(34)S isotopic changes directly linked to orbitally tuned records of climate change through the Cenozoic. Such measurements have not previously been possible due to limitations of sensitivity in conventional IRMS-based techniques. However, the recent development of CAS analysis by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) now allows us to work on samples containing just a few nmol of sulfur with accuracy for δ^(34)S values approaching 0.1‰ and, consequently, to analyze hand-picked samples of foraminifera shells. Here we report the results of culture experiments with the planktonic species Orbulina universa, that establish a shell:seawater δ^(34)S calibration for future applications to the fossil record. Our new method uses <650 μg of carbonate (∼15 shells) per analysis. The results show that S isotopes are fractionated consistently by −1‰ between seawater and O. universa tests. We also demonstrate that O. universa faithfully records the [SO^(2−)_(4)]/[Ca^(2+)] ratio of the seawater in which it grew

PIAS3 modulate HIV-1 integrase SUMOylation

International audienc

Nitrogen isotope record of a perturbed paleoecosystem in the aftermath of the end-Triassic crisis, Doniford section, SW England

International audience[1] The Triassic-Jurassic transition (TJ) is characterized by successive perturbations of the carbon cycle during a time of biotic disruption as recorded by the carbon isotopic composition of organic matter (δ13Corg). The nitrogen isotopic composition of sedimentary organic matter (δ15Norg) constitutes a key parameter to explore the functioning of the ecosystem during carbon cycle perturbations and biological crises, because it provide information on seawater redox conditions and/or nutrient cycling. Here we report the first continuous δ15Norg record across the TJ transition at the Doniford Bay section (Bristol Channel Basin, UK), combined with δ13Corg, kerogen typology and carbon (δ13Cmin) and oxygen (δ18Omin) isotopic composition of bulk carbonates. The end Triassic is characterized by a major negative excursion both in δ13Corg and δ13Cmin, very low TOC (Total Organic Carbon, wt%) and high δ15Norg values, associated with a sea level lowstand. A second δ13Corg negative excursion occurs during the lower Hettangian. This interval is characterized by phases of carbonate production increase alternated with phases of exceptional accumulations of type I organic matter (up to 12%) associated with lower δ15Norg and δ13Corg. This alternation likely reflects a succession of nutrient input increase to the basin leading to enhanced productivity and eutrophication, which promoted a primary production driven by organic-walled prokaryotic organisms. The following OM export increase generates anaerobic conditions within the basin. These events occur between periods of relatively good seawater column ventilation and nutrient recycling boosting the carbonate producer recovery. Ecosystems remain perturbed in the Bristol Channel Basin during the aftermath of the end-Triassic crisis