Changements côtiers et inondations suite au passage d’un ouragan extrême (Irma, 2017) aux Petites Antilles

Cette étude porte sur les changements côtiers et les inondations suite au passage d’un ouragan de catégorie 5 (Irma) les 5 et 6 septembre 2017 sur les îles de Saint-Martin et Saint-Barthélemy aux Antilles. Deux missions de terrain à t+2 mois et t+8 mois sur les deux îles ont permis d’analyser les impacts de l’ouragan Irma sur des côtes basses particulièrement sensibles aux événements météo-marins extrêmes et aux pressions anthropiques. Le retour d’expérience a été réalisé sur les côtes les plus touchées par l’évènement. Pour comparer les impacts de l’ouragan Irma et les interactions avec les systèmes côtiers et les infrastructures côtières, nous avons choisi d’analyser des côtes peu urbanisées et des littoraux densément aménagés. La méthode a reposé sur l’analyse d’images satellites avant le passage de l’ouragan Irma et l’analyse d’images drones post-évènement. Elle s’est aussi appuyée sur des observations géomorphologiques, la mesure des hauteurs de vagues et la cartographie des espaces inondées. Les systèmes côtiers ont répondu très différemment en fonction du degré d’artificialisation de la côte, révélant des changements côtiers variés, des transferts sédimentaires perturbés et une influence sur les hauteurs d’eau maximales à la côte.This study deals with the coastal changes, flooding and damage after the passage of a category 5 hurricane (Irma) on 6 September 2017 over the islands of Saint-Martin and Saint-Barthélemy in the Lesser Antilles. Two field work were made 2 and 8 months after the catastrophe over the two islands. It made it possible to analyze the impacts of Hurricane Irma on the low-lying shores that are particularly susceptible to extreme cyclonic events and anthropogenic stressors. The field work was made on the coasts most affected by the cyclonic event. To compare impacts of hurricane Irma and interactions with coastal systems and coastal infrastructure, we chose to analyze undeveloped to highly urbanized coasts. The method was based on the analysis of satellite images and Unmanned Aerial Vehicle surveys. It also relied on qualitative observations, geomorphological and sedimentary surveys and the measurement of wave run up and the mapping of flooded areas. The coastal system revealed a variety of morpho-sedimentary responses on both the natural and highly urbanized coasts, showing varied coastal changes, perturbed sedimentary transfers and the effects of coastal structures and street on flow channeling and on water level increas

Edema Toxin Impairs Anthracidal Phospholipase A2 Expression by Alveolar Macrophages

Bacillus anthracis, the etiological agent of anthrax, is a spore-forming Gram-positive bacterium. Infection with this pathogen results in multisystem dysfunction and death. The pathogenicity of B. anthracis is due to the production of virulence factors, including edema toxin (ET). Recently, we established the protective role of type-IIA secreted phospholipase A2 (sPLA2-IIA) against B. anthracis. A component of innate immunity produced by alveolar macrophages (AMs), sPLA2-IIA is found in human and animal bronchoalveolar lavages at sufficient levels to kill B. anthracis. However, pulmonary anthrax is almost always fatal, suggesting the potential impairment of sPLA2-IIA synthesis and/or action by B. anthracis factors. We investigated the effect of purified ET and ET-deficient B. anthracis strains on sPLA2-IIA expression in primary guinea pig AMs. We report that ET inhibits sPLA2-IIA expression in AMs at the transcriptional level via a cAMP/protein kinase A–dependent process. Moreover, we show that live B. anthracis strains expressing functional ET inhibit sPLA2-IIA expression, whereas ET-deficient strains induced this expression. This stimulatory effect, mediated partly by the cell wall peptidoglycan, can be counterbalanced by ET. We conclude that B. anthracis down-regulates sPLA2-IIA expression in AMs through a process involving ET. Our study, therefore, describes a new molecular mechanism implemented by B. anthracis to escape innate host defense. These pioneering data will provide new molecular targets for future intervention against this deathly pathogen

New Linguliformean Brachiopods from the Lower Tremadocian (Ordovician) of The Brabant Massif, Belgium, with comments on contemporaneoux faunas from the Stavelot-Venn Massif

Lower Ordovician brachiopod macrofaunas in Belgium (Avalonia) are seldom collected and studied due to the poor preservation of material. Here we describe a new fauna of linguliformean brachiopods from the Chevlipont Formation (lower Tremadocian) in the Brabant Massif. The fauna is of low diversity (at least three species belonging to Rosobolus?, Thysanotos, and Broeggeria have been identified) and is dominated by B. cf. salteri (Holl). Low diversity linguliformean brachiopod assemblages in a peri-Gondwanan terrane are characteristic of the lowermost Ordovician. Such assemblages are rooted in the Cambrian indicating that their geographic distribution during the early Ordovician was controlled by the radiation and dispersion of lineages surviving through the latest Cambrian-earliest Tremadocian linguliformean brachiopods taxonomic crisis. In addition we figure for the first time and comment on contemporaneous brachiopod faunas from the Stavelot-Venn Massif in SE Belgium. Finally, we present new graptolite data that enable a more precise constraint on the age for the Solwaster Member of the Jalhay Formation in the Stavelot-Venn Massif.IGCP 73

Mortalité et cyclones en Guadeloupe (Antilles françaises)

Cet article pose les bases méthodologiques d’un catalogue historique des évènements hydro-météorologiques significatifs et mortels qui ont frappé l’archipel de Guadeloupe et les îles du Nord (Saint-Martin et Saint-Barthélemy) depuis 1635. Pour la période récente, post 1950, il est doublé d’un Système d’Information Géographique permettant de localiser et de renseigner chaque victime avec son profil, son comportement, les circonstances et causes du décès. Outre l’apport de bilans humains consolidés, ce nouveau référentiel géo-historique permet d’analyser l’évolution de la mortalité au cours du temps en lien avec les principaux facteurs de vulnérabilité. On peut en tirer un certain nombre d’enseignements utiles pour guider la prévention des risques en Guadeloupe.This paper lays the methodological basis for a historical catalogue of significant and deadly hydro-meteorological events that have occurred in the Guadeloupe archipelago and the northern islands since 1635. For the recent period, post 1950, it is supplemented by a Geographical Information System used to locate and inform each victim with his profile, his behavior, the circumstances and causes of death. In addition to the contribution of consolidated human death tolls, this new geo-historical framework makes it possible to analyze the evolution of mortality over time in relation to the main factors of vulnerability. A number of useful lessons can be drawn from this to guide risk prevention in Guadeloupe

The effect of short-chain fatty acids on human monocyte-derived dendritic cells

The gut microbiota is essential for human health and plays an important role in the pathogenesis of several diseases. Short-chain fatty acids (SCFA), such as acetate, butyrate and propionate, are end-products of microbial fermentation of macronutrients that distribute systemically via the blood. The aim of this study was to investigate the transcriptional response of immature and LPS-matured human monocyte-derived DC to SCFA. Our data revealed distinct effects exerted by each individual SCFA on gene expression in human monocyte-derived DC, especially in the mature ones. Acetate only exerted negligible effects, while both butyrate and propionate strongly modulated gene expression in both immature and mature human monocyte-derived DC. An Ingenuity pathway analysis based on the differentially expressed genes suggested that propionate and butyrate modulate leukocyte trafficking, as SCFA strongly reduced the release of several pro-inflammatory chemokines including CCL3, CCL4, CCL5, CXCL9, CXCL10, and CXCL11. Additionally, butyrate and propionate inhibited the expression of lipopolysaccharide (LPS)-induced cytokines such as IL-6 and IL-12p40 showing a strong anti-inflammatory effect. This work illustrates that bacterial metabolites far from the site of their production can differentially modulate the inflammatory response and generally provides new insights into host-microbiome interactions

Magnetite solubility and iron transport in magmatic-hydrothermal environments

Abstract-We have examined the effect of pressure on the apparent equilibrium constant, K=, for magnetite solubility (Fe 3 O 4 mt ϩ 6HCl fluid ϩ H 2 fluid ϭ 3FeCl 2 fluid ϩ 4H 2 O fluid ) and the relative iron-carrying capacities of magmatic vapor and brine by conducting experiments in a rhyolite melt-vapor-brine-magnetite system at 800°C, f O 2 ϭ NNO and pressures ranging from 100 to 145 MPa. Iron concentrations in synthetic vapor and brine fluid inclusions were quantified by using laser-ablation inductively-coupled-plasma-mass-spectrometry (LA-ICPMS). Hydrogen chloride (HCl) concentrations in magmatic vapor were inferred by potentiometric measurements of H ϩ in quenched run product fluids. These data yield calculated values for log K=, assuming a H 2 O ϭ X H 2 O , of 1.7, 4.9, 6.2, 6.8 and 9.1 at 100, 110, 130, 140 and 145 MPa, respectively. The concentration of iron in magmatic vapor increases by an order of magnitude, whereas the concentration of iron in magmatic brine remains constant (within 1) with increasing pressure as the 800°C critical pressure is approached along the vapor-brine solvus. The concentrations of iron in vapor and brine fluid inclusions yield calculated partition coefficients (D Fe v/b ) of 0.05, 0.14, 0.27 and 0.56 at 110, 130, 140 and 145 MPa, respectively. Our data reveal that pressure fluctuations may significantly affect the value of log K=. More importantly, the data demonstrate conclusively that a significant amount of iron can be transported by a low-density aqueous vapor in the magmatic-hydrothermal environment

Refining seismic parameters in low seismicity areas by 3D trenching: The Alhama de Murcia fault, SE Iberia.

Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 mm per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 +/- 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 +/- 1.1 ka and 21.9-22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault: The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 53 and 63 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas. (C) 2016 Elsevier B.V. All rights reserved

WP2 final report

This document summarises the significant results in work package 2 of the DigiMon project. Detailed descriptions and results from each task can be found in the referenced deliverables and publications