A sea spray generation function for fetch-limited conditions

International audienceThis paper presents a sea spray generation function for aerosols produced by bubbles bursting that accounts for the effects of fetch. This is achieved by introducing a fetch-dependent model for the whitecap fraction, which is valid for fetch-limited conditions, i.e. steady-state conditions of the wave field in the whitecap droplet flux derived by Monahan et al. (1986). The aerosol generation fluxes calculated by this method show an enhancement of the aerosol production with increasing fetch. However, the predicted generation fluxes are lower than those calculated by using the classical model for the whitecap fraction proposed by Monahan and O'Muircheartaigh (1980). The results are then compared to aerosol size distributions measured in a Mediterranean coastal site at various fetch lengths. The data confirm the role of fetch, through its influence on marine aerosol generation and subsequent particle dispersion. The aerosol size distributions are divided into "fine" and "coarse" fractions. Submicrometer particles decrease in concentration at larger fetch, while the concentrations of super micron aerosols increase with increasing fetch

Le détail qui tue (Le Pen et les médias)

À propos de la célèbre question du « détail » soulevée par les propos tenus en 1987 par Jean-Marie Le Pen et régulièrement reprise depuis, on se propose, à travers une analyse minutieuse du document, d’en mettre au jour un aspect resté occulté pour des raisons qui ne tiennent pas à la négligence : en effet, au-delà du « lapsus » commis par Le Pen, qui révèle son substrat idéologique dénié, et de ses commentaires autojustificateurs, qui permettent une analyse affinée de son mode de raisonnement, c’est la logique du couple « pervers » (Daniel Sibony) qu’il forme avec les médias qui se trouve concrètement révélée

The Neonatal Development of Intraepithelial and Lamina Propria Lymphocytes in the Murine Small Intestine

During early neonatal life, important changes occur in the gut. The intestine is challenged by both milk and a microbial flora. Later on, at weaning, the diet of mice changes from milk to pelleted food leading to changes in microbial contents. This period seems essential for a complete development of the mucosal immune system. We investigated the development of both intraepithelial (IEL) and lamina propria lymphocytes (LPL), from day 5, and every 5 days, up to day 30 after birth. IEL and LPL were isolated from the small intestine and the phenotype was assessed by FACS analyses, using antibodies for detection of T-cell markers CD3, TCRαβ, TCRγδ, CD4, CD8α, CD8β, CD5, CD18, CD54, and CD49d. Our data show a clear increase in the number of LPL just before weaning, while the number of IEL increased after day 15. A more mature pattern of membrane antigen expression of both IEL and LPL was observed at weaning. The adhesion molecules CD18, CD54, and CD49d, essential for cellular communication of lymphocytes, showed an expression peak at weaning. In conclusion, the mouse mucosal immune system develops during the first 3 weeks of neonatal life leading to the formation of a more mature immune system at weaning

Circulation côtière en Méditerranée Nord Occidentale (courantométrie par radar HF et couplage avec un modèle numérique)

Le radar HF est actuellement le seul instrument courantométrique permettant d'obtenir une description synoptique à haute résolution spatiale et temporelle de la circulation côtière de surface. Un système radar déployé depuis 2010 en Méditerranée sur les côtes varoises offre pour la première fois une description exhaustive de la circulation, encore peu documentée dans cette zone.La cartographie des courants se fait classiquement en combinant les mesures d'au moins deux radars. Cependant des résultats significatifs ont été obtenus avec un seul radar concernant : l'identification de tourbillons méso-échelle ; la signature de phénomènes périodiques affectant la circulation superficielle dans les bandes diurne, inertielle et semi-diurne ; et les caractéristiques et les instabilités du Courant Nord Méditerranéen (CN).L'assimilation des mesures radar au moyen d'un lisseur de Kalman d'ensemble dans un modèle régional de la Méditerranée Nord Occidentale a été réalisée pour la première fois dans la zone d étude. Cette méthode, qui contraint les courants de surface en optimisant le vent et les forçages aux frontières ouvertes, améliore la description de la veine du CN en vitesse et positionThe HF radar is the sole instrument being able to monitor the surface coastal current at very high spatial and temporal resolution. A radar system deployed since 2010 on the Var coast (Western Mediterranean Sea) provides for the first time a comprehensive picture of the circulation, which remains poorly documented in this area.Surface current mapping is conventionally performed by combining measurements of at least two radars. However, significant results were obtained with a single radar concerning: the identification of mesoscale vortices; the signature of periodic phenomena affecting the surface circulation in the diurnal, inertial and semi-diurnal bands; and the features and instabilities of the North Mediterranean Current (NC).The assimilation of radar measurements using an ensemble Kalman smoother in a regional model of the North-Western Mediterranean Sea was performed for the first time in the study area. This method, which constraints the surface currents by wind and open boundary conditions optimisation, improves the simulation of the NC vein in terms of speed and position.TOULON-Bibliotheque electronique (830629901) / SudocSudocFranceF

Mycotoxines et éléments traces métalliques : co-contamination et toxicité croisée.

Ce numéro est constitué d’articles issus du colloque « Contaminants alimentaires – approches émergentes pour connaître et prévenir le risque » qui s’est tenu à Paris le 19 décembre 2018.Food safety is a major concern worldwide. Most of the toxicological data concern the effects of foodcontaminant when present alone; however, food and feedstuff are usually contaminated by more thanone toxic compound. In this study, we focused on the contamination and toxicity of the mixture betweena metallic chemical element, cadmium (Cd) and a mycotoxin, deoxynivalenol (DON). Their individualand combined cytotoxicity were first investigated in human cell lines from kidney, intestine, blood andliver. The types of interactions, determined by the combination index method, revealed the interaction isorgan specific. When looking more precisely at the intestine, we observed that the interaction betweenDON and Cd on the barrier function varied according to the dose and duration of exposure. Theexpression of junctional proteins was greatly reduced in any exposed cells, with a greater effect with themixture in DON+Cd. In vivo, intestine of rat exposed to DON, Cd or both, showed a higher lesionalscore and lower junctional-proteins expression than control animals. Taken together, our resultsdemonstrate that combined exposure to DON and Cd can induces more effect than a single exposureThey also reveal the complexity of the interaction between food contaminantsLa sécurité sanitaire des aliments est une préoccupation majeure. La plupart des donnéestoxicologiques concernent les effets des contaminants alimentaires présents seuls. Cependant, lesaliments sont généralement contaminés simultanément par plusieurs toxiques. Nous sommesintéressés à la contamination et à la toxicité du mélange d'un élément trace métallique, le cadmium (Cd)et d'une mycotoxine, le déoxynivalénol (DON). Leur cytotoxicité a d'abord été étudiée dans différenteslignées cellulaires humaines d'origine rénale, intestinale, sanguine et hépatique. L'analyse desinteractions, par l'indice de combinaison, montre que le type d'interaction est organe-spécifique. Uneanalyse plus fine sur l'intestin montre que l'interaction entre ces deux contaminants sur la fonction debarrière varie en fonction de la dose et de la durée d'exposition. L'expression des protéines de jonctionest réduite sur les cellules exposées aux contaminants, avec une réduction plus importante pour lemélange. In vivo, l'intestin des rats exposés au DON, au Cd ou au mélange a montré un score lésionnelplus élevé et une expression plus faible des protéines de jonction que les contrôles. De façon globale,nos résultats montrent qu'une exposition au mélange DON et Cd peut induire effets plus importantsqu'une exposition à un seul de ces contaminants. Ils révèlent également la complexité des interactionsentre les contaminants alimentaires

Phylogenomic analyses predict sistergroup relationship of nucleariids and Fungi and paraphyly of zygomycetes with significant support

Abstract Background Resolving the evolutionary relationships among Fungi remains challenging because of their highly variable evolutionary rates, and lack of a close phylogenetic outgroup. Nucleariida, an enigmatic group of amoeboids, have been proposed to emerge close to the fungal-metazoan divergence and might fulfill this role. Yet, published phylogenies with up to five genes are without compelling statistical support, and genome-level data should be used to resolve this question with confidence. Results Our analyses with nuclear (118 proteins) and mitochondrial (13 proteins) data now robustly associate Nucleariida and Fungi as neighbors, an assemblage that we term 'Holomycota'. With Nucleariida as an outgroup, we revisit unresolved deep fungal relationships. Conclusion Our phylogenomic analysis provides significant support for the paraphyly of the traditional taxon Zygomycota, and contradicts a recent proposal to include Mortierella in a phylum Mucoromycotina. We further question the introduction of separate phyla for Glomeromycota and Blastocladiomycota, whose phylogenetic positions relative to other phyla remain unresolved even with genome-level datasets. Our results motivate broad sampling of additional genome sequences from these phyla

Orbital dichotomy of Fermi liquid properties in Sr2_2RuO4_4 revealed by Raman spectroscopy

We report a polarization-resolved Raman spectroscopy study of the orbital dependence of the quasiparticles properties in the prototypical multi-band Fermi liquid Sr\textsubscript{2}RuO\textsubscript{4}. We show that the quasiparticle scattering rate displays $\omega^{2}$ dependence as expected for a Fermi liquid. Besides, we observe a clear polarization-dependence in the energy and temperature dependence of the quasiparticle scattering rate and mass, with the $d_{xz/yz}$ orbital derived quasiparticles showing significantly more robust Fermi liquid properties than the $d_{xy}$ orbital derived ones. The observed orbital dichotomy of the quasiparticles is consistent with the picture of Sr\textsubscript{2}RuO\textsubscript{4} as a Hund's metal. Our study establishes Raman scattering as a powerful probe of Fermi liquid properties in correlated metals.Comment: 9 pages, 4 figures, Supplementary Materials available at publisher sit