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Effects of vegetation cover and season on soil nitrifiers in an African savanna: Evidence of archaeal nitrifier inhibition by grasses
No full textInternational audienceFor the first time in a savanna, we analysed the joint influence of climate seasonality and plant cover type on the abundances and transcription levels of bacterial and archaeal nitrifiers, and nitrification enzyme activity (NEA). The dominant tree and grass species stimulated and inhibited nitrification, respectively: NEA was 4-fold higher and 5-fold lower under trees and grasses than in bare soil, respectively. The abundances of bacterial nitrifiers (AOB-amoA) followed the same trend as the abundances of total bacteria did, with higher abundances under grasses and trees than in bare soil and higher abundances during the wet season, but AOB-amoA transcripts were always below detection limit. In contrast, the abundances of archaeal nitrifiers (AOA-amoA) were 13-fold lower under grasses and 2-fold higher under trees than in bare soil, and the AOA-amoA transcript level decreased under grasses during the wet season. Our results show that nitrifier abundances and transcriptional activities are highly seasonal and that nitrification is likely to be dominated by AOA-amoA in these savanna soils. We show for the first time that a dominant grass species (Hyparrhenia diplandra) of humid African savannas inhibits nitrification through marked decreases in AOA-amoA expression levels
POTENTIAL METHOD AND PROJECTION THEOREMS FOR MACROSCOPIC HAUSDORFF DIMENSION
No full textThe macroscopic Hausdorff dimension Dim H (E) of a set E ⊂ R d was introduced by Barlow and Taylor to quantify a "fractal at large scales" behavior of unbounded, possibly discrete, sets E. We develop a method based on potential theory in order to estimate this dimension in R d. Then, we apply this method to obtain Marstrand-like projection theorems: given a set E ⊂ R 2 , for almost every θ ∈ [0, 2π], the projection of E on the straight line passing through 0 with angle θ has dimension equal to min(Dim H (E) , 1)
Le "bien-être" et le "mal-être" adolescent face aux réseaux sociaux numériques (RSN)
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The two-top molecule 3-penten-2-one: Acetyl methyl torsion in α,β-unsaturated ketones
No full textInternational audienceUsing a molecular jet Fourier transform spectrometer, the microwave spectrum of E-3-penten-2-one, also called methyl propenyl ketone, was recorded in a range from 2.0 to 26.5 GHz. Two conformers, antiperiplanar (ap) and synperiplanar (sp), could be identified. Complicated splitting patterns arising due to the internal rotation of the acetyl methyl and propenyl methyl groups could be resolved, and all measured rotational transitions were fitted to measurement accuracy. The barrier heights of the acetyl methyl group are 434.149(37) cm−1 and 358.076(26) cm−1 for the ap and sp conformers, respectively. For the propenyl methyl group, the barrier is 581.903(45) cm−1 for the ap conformer and 595.271(71) cm−1 for the sp conformer. By comparing these results to those of other ketones categorized in a class system connecting the internal rotation of the acetyl methyl group to the structures of the molecules, we extended the categorization with a new class for α,β-unsaturated ketones
Reconstruction post-Irma à Saint-Martin : réviser les documents d’occupation des sols pour recomposer un territoire moins vulnérable
No full textInternational audienceOn September 6, 2017, Hurricane Irma (category 5 on the Saffir-Simpson scale) passed through Saint Martin (French West Indies). Based on a field survey conducted in the French part of the island, this work aims to characterise the preventive opportunity of the post-disaster reconstruction period by questioning the land use reorganisation (via the revision of the Plan de Prévention des Risques Naturels – PPRN). The IPCC, in its 2019 report on the Oceans and Cryosphere, highlights that societies are developing a multitude of measures to adapt to coastal risks, most often in response to disasters. The analysis of reconstruction choices and their consequences therefore provides information on the concrete adaptation processes. By analysing the revision procedure of the PPRN of Saint-Martin, we examine the State’s willingness to integrate the ‘lessons learned’ from Irma, and question how it reveals the dysfunctions and tensions that pre-existed in the socio-territorial system. This concrete example shows the obstacles and levers to the implementation of a preventive reconstruction strategy that involves the reorganisation of the territory to take better account of present and future risks. This study allows us to conclude on the paradox of post-disaster recovery, which is both a ‘window of opportunity’ and a catalyst of vulnerabilities, an opportunity for change and an illustration of the weight of past legacies and the inertia of systems.Le 6 septembre 2017, l’ouragan Irma (de catégorie 5 sur l’échelle de Saffir-Simpson) a traversé Saint Martin (Antilles françaises). Fondé sur une enquête de terrain menée dans la partie française de l’île, ce travail a pour objectif de caractériser l’opportunité préventive de la période de reconstruction post-catastrophe en questionnant la recomposition du territoire (via la révision du Plan de Prévention des Risques Naturels – PPRN). Le GIEC dans son rapport de 2019 met en évidence que les sociétés développent une multitude de mesures d’adaptation aux risques côtiers, le plus souvent en réponse aux catastrophes. L’analyse des choix de reconstruction et de leurs conséquences permet donc de renseigner sur les modalités concrètes d’adaptation. En analysant le processus de révision du PPRN de Saint-Martin, nous interrogeons la volonté de l’État d’intégrer les « leçons apprises » d’Irma, et questionnons comment elle révèle les dysfonctionnements et les tensions qui préexistaient sur le territoire. Cet exemple concret donne à voir les freins et leviers à la mise en œuvre d’une stratégie de reconstruction préventive, qui passe par la réorganisation de l’occupation des sols, pour prendre davantage en compte les risques présents et futurs. Cette étude permet de conclure sur le paradoxe de la reconstruction, à la fois « fenêtre d’opportunité » et catalyseur des vulnérabilités, opportunité de changement et illustration du poids des héritages passés et de l’inertie des systèmes
Former les managers de demain: Kit créatif pour les formateurs
No full textInternational audienceNotre société se transforme à grande vitesse et fait émerger de nouveaux enjeux économiques, sociaux, sociétaux et environnementaux. Ces évolutions remettent en cause les pratiques managériales des entreprises.Pour répondre à ces nouveaux défis, le conseil, la formation et l’enseignement du management se renouvellent et se tournent vers de nouvelles approches mobilisant le jeu, le monde virtuel, l’art, le numérique ou le design thinking.Cet ouvrage a pour ambition de diffuser des expériences pédagogiques créatives développées par des enseignants-chercheurs de l’enseignement supérieur et adaptées à ces nouveaux enjeux. Tout en exerçant un regard réflexif et académique sur ces expériences, ce livre servira de boîte à outils pour les consultants, les enseignants et les formateurs désireux d’accroître leur palette d’approches et de méthodes pédagogiques pour former à un management renouvelé
Chemical and genetic evidences that multiple hornet colonies attack honeybee colonies
No full textInternational audienceThe yellow-legged hornet, Vespa velutina nigrithorax, is an invasive species that is causing numerous ecological and economic problems, particularly for beekeepers, whose apiaries are seriously affected by hornet predation. The effects may be intensified if hornet workers from different colonies are preying upon bees from the same apiary. Therefore, to determine whether such could occur, we sampled hornets found within identifiable colonies versus in front of bee hives. We employed two complementary methodological approaches: the analysis of chemical markers (i.e., cuticular hydrocarbons) and genetic markers (i.e., microsatellites). Although there was chemical variation among hornets, we determined that at least two chemically homogeneous hornet groups could be found within each apiary studied (using Kmeans clustering). Furthermore, when hornet chemical dissimilarity was quantified at three different levels (within apiaries, within hornet colonies, and between hornet colonies), we discovered that the within-apiary dissimilarity was intermediate relative to within-colony and between-colony dissimilarity, suggesting that the hornets within a given apiary represented a mixture of individuals from more than one colony. Based on the genetic markers, hornet genetic diversity was low at the population level, as expected for this introduced species. That said, the genetic results mirrored the chemical results: genetic dissimilarity was larger between colonies and smaller within colonies. However, the hornets within a given apiary displayed an intermediate dissimilarity value. Consequently, both our chemical and genetic findings suggested that apiaries could be attacked by hornets from more than one colony
Neonatal cyanosis with Hb St Mandé, a low O 2 affinity hemoglobin variant affecting β‐globin
No full textInternational audienc
Clinical outcomes after treatment with direct antiviral agents: beyond the virological response in patients with previous HCV-related decompensated cirrhosis
No full textInternational audienceBACKGROUND: In HCV-infected patients with advanced liver disease, the direct antiviral agents-associated clinical benefits remain debated. We compared the clinical outcome of patients with a previous history of decompensated cirrhosis following treatment or not with direct antiviral agents from the French ANRS CO22 HEPATHER cohort. METHODS: We identified HCV patients who had experienced an episode of decompensated cirrhosis. Study outcomes were all-cause mortality, liver-related or non-liver-related deaths, hepatocellular carcinoma, liver transplantation. Secondary study outcomes were sustained virological response and its clinical benefits. RESULTS: 559 patients met the identification criteria, of which 483 received direct antiviral agents and 76 remained untreated after inclusion in the cohort. The median follow-up time was 39.7 (IQR: 22.7-51) months. After adjustment for multivariate analysis, exposure to direct antiviral agents was associated with a decrease in all-cause mortality (HR 0.45, 95% CI 0.24-0.84, p = 0.01) and non-liver-related death (HR 0.26, 95% CI 0.08-0.82, p = 0.02), and was not associated with liver-related death, decrease in hepatocellular carcinoma and need for liver transplantation. The sustained virological response was 88%. According to adjusted multivariable analysis, sustained virological response achievement was associated with a decrease in all-cause mortality (HR 0.29, 95% CI 0.15-0.54, p < 0.0001), liver-related mortality (HR 0.40, 95% CI 0.17-0.96, p = 0.04), non-liver-related mortality (HR 0.17, 95% CI 0.06-0.49, p = 0.001), liver transplantation (HR 0.17, 95% CI 0.05-0.54, p = 0.003), and hepatocellular carcinoma (HR 0.52, 95% CI 0.29-0.93, p = 0.03). CONCLUSION: Treatment with direct antiviral agents is associated with reduced risk for mortality. The sustained virological response was 88%. Thus, direct antiviral agents treatment should be considered for any patient with HCV-related decompensated cirrhosis. TRIAL REGISTRATION: ClinicalTrials.gov registry number: NCT01953458
Plurilinguisme et enseignement des mathématiques: Mise en perspectives des Journées Plurimaths 2020
No full textInternational audienceCroisement de deux point de vue : les langages pour dire-penser- faire les mathématiques d'une part, et les mathématiques qui se font, existent et se transmettent par les langages d'autre part. Pour donner à voir, à lire, à faire, à penser, à imaginer, trente chercheurs, formateurs, praticiens ont accordé leur savoir et savoir-faire pour composer cet opus de treize chapitres.Auteurs : Myriam ABOU-SAMRA, Nathalie AUGER, Céline BEAUGRAND, Michel CANDELIER, Julie CANDY , Alexandre CA V ALCANTE, Aurélie CHESNAIS, Isabelle CROS, Jim CUMMINS, Delphine D'HONDT, Fanny DUREYSSEIX, Pierre ESCUDÉ, Laurent GAJO, Christophe HACHE, Martine JAUBERT, Emile JENNY, Emilie KASAZIAN, Emmanuelle LE PICHON-VORSTMAN, Jérémie MAUGEZ, Catherine MENDONÇA DIAS, Ismaïl MILI, Karine MILLON FAURÉ, Marianne MOULIN, Estelle MOUMIN, Florence PETEERS, Caroline POISARD, Maryse REBIÈRE, Avenilde ROMO VÁZQUEZ, Jean-Jacques SALONE, Élodie SURGET