Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Serpentinites are one of the major components of the oceanic lithosphere and are stable in the slab and the mantle wedge up to 100-150 km depth in subduction zones. During oceanic mantle hydration and alteration, they trap trace and fluid mobile (FME: B, Li, As, Sb, Rb, Ba, Cs, Sr, U and Pb) elements that participate to elemental transfer occurring between the dehydrating slab and the mantle wedge in subduction context. The Lanzo massif is an eclogitized oceanic lithosphere that preserved its oceanic structure and recorded different steps of serpentinization/de-serpentinization from oceanic lizardite to prograde antigorite in subduction context, up to its dehydration and secondary olivine crystallization, and finally retrograde antigorite during massif exhumation. It constitutes a suitable place to study trace element behavior during serpentinization/de-serpentinization processes and associated chemical transfers between the different envelopes of the oceanic lithosphere and the mantle wedge. Geochemical analyses of serpentine and associated minerals show that the serpentinization/de-serpentinization of the Lanzo massif took place in a relatively closed system without significant trace element transfer between the different parts of the oceanic lithosphere. In the deeper part of the lithosphere, from the slightly serpentinized mantle peridotites (SSP, < 20% serpentinization) to the paleo-Moho, composed of massive serpentinites (MS, 80% serpentinization), the trace elements mobility is reduced. The chemical composition of lizardite and antigorite is homogenized with the local degree of serpentinization: in SSP, serpentine veins composition is inherited from the host mineral while, in MS, their composition is homogenous between destabilized phases at the scale of the outcrop (~ 5 m). In the shallowest part of the oceanic lithosphere, from the paleo-Moho to the oceanic paleo-seafloor, the serpentinites are foliated (FS, > 90% serpentinization). In that zone, the alpine deformation enhances the mobility of trace elements and permits their redistribution and the homogenization of antigorite composition at massif scale. Locally, in the SSP and MS, the crystallization of metamorphic veins of ~ 1-2 m corresponds to channelized fluid flows that allowed fluid transfers - and thereby trace elements - to longer distance. The successive crystallizations of antigorite and then olivine are accompanied by a diminution of some FME (B, Li, As, Sb, Ba, Rb) and Eu contents attesting that these elements are removed from slab to mantle wedge during subduction.
ISSN: 0009-2541

hal-00937661
https://hal.archives-ouvertes.fr/hal-00937661
DOI : 10.1016/j.chemgeo.2013.08.025

Éditeur(s) : HAL CCSD
Résumé : Patagonia is well known for spectacular occurrences of a variety of glacial-derived landforms and deposits and for a long history of ancient glaciations. In this paper, we first review the diverse evidence that demonstrates the development of glacial-related sedimentary units within the Central Patagonian Cordillera since 7 Ma. Well preserved glacial landforrns at the top surface of mesetas on both sides of the Lago General Carrera-Buenos Aires are described: the Meseta Guenguel to the north, and the volcanic Meseta del Lago Buenos Aires to the south. The latter meseta corresponds to a 3 Ma old, morphologically inverted paleo-piedmont, based on Ar/Ar dates of the uppermost lava flows. It shows evidence of glacier advances to the NE direction. Over a distance of 20 km, glacial landforms observed by remote sensing data and digital elevation model define glacial tongues that were fed by the Cordillera reliefs to the west. These lobes are now beheaded from their westward sources along a morpho-structural corridor that bounds the Meseta del Lago Buenos Aires to the west. These remnants can be correlated with the oldest glacial landforms recognized north of Lago General Carrera-Buenos Aires, on the Meseta Guenguel that form the Chipanque moraine system. From these features it is concluded that the glacial drainage network of Central Patagonia has been strongly modified following relief inversion in response to erosion processes and to tectonic causes. Changes occurred after 3 Ma, from a smooth piedmont surface covered by an extensive ice mantle ending with ample glacial lobes, to the current series of deeply incised glacial valleys such as the Lago General Carrera-Buenos Aires depression. These new data bear important constraints on the history and development of the first glaciations in southern South America.
ANDEAN GEOLOGY

hal-00512682
https://hal.archives-ouvertes.fr/hal-00512682

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Our ability to decipher the mechanisms behind metamorphic transformation processes depends in a major way on the extent to which crystallographic and microstructural information is transferred from one stage to another. Within the Leka Ophiolite Complex in the Central Norwegian Caledonides, prograde olivine veins that formed by dehydration of serpentinite veins in dunites exhibit a characteristic distribution of microstructures: The outer part of the veins comprises coarse-grained olivine that forms an unusual, brick-like microstructure. The inner part of the veins, surrounding a central fault, is composed of fine-grained olivine. Where the fault movement included a dilational component, optically clear, equant olivine occurs in the centre. Electron backscatter diffraction mapping reveals that the vein olivine has inherited its crystallographic preferred orientation (CPO) from the olivine in the porphyroclastic host rock; however, misorientation is weaker and associated to different rotation axes. We propose that prograde olivine grew epitaxially on relics of mantle olivine and thereby acquired its CPO. Growth towards pre-existing microfractures along which serpentinisation had occurred led to straight grain boundaries and a brick-like microstructure in the veins. When dehydration embrittlement induced slip, a strong strain localisation on discrete fault planes prevented distortion of the CPO due to cataclastic deformation; grain size reduction did not significantly modify the olivine CPO. This illustrates how a CPO can be preserved though an entire metamorphic cycle, including hydration, dehydration, and deformation processes, and that the CPO and the microstructures (e.g. grain shape) of one phase do not necessarily record the same event.
ISSN: 0010-7999

hal-01622643
https://hal.archives-ouvertes.fr/hal-01622643
DOI : 10.1007/s00410-017-1378-5

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
In Alpine Corsica (France), deeply subducted metabasalts are well preserved as lawsonite-bearing eclogite (Law-Ecl), occurrence of which is restricted to similar to 10 localities worldwide. The Corsican Law-Ecl, consisting of omphacite + lawsonite + garnet + phengite + titanite, occurs as both single undeformed metabasaltic pillows surrounded by lawsonite blueschist (Law-Bs), and carbonate-bearing eclogitic veins. Law-Bs are found as variably deformed metabasaltic pillows locally cross-cut by eclogitic veins and consist of glaucophane + actinolite + lawsonite + garnet + phengite + titanite. Field evidence and microstructures reveal that both Law-Ecl and Law-Bs are stable at the metamorphic peak in the lawsonite-eclogite stability field. Isochemical phase diagrams (pseudosections) calculated for representative Law-Ecl and Law-Bs samples indicate that both lithologies equilibrated at the same conditions of similar to 520 +/- 20 degrees C and 2.3 +/- 0.1 GPa. Therefore, the coexistence at the same peak metamorphic conditions of Law-Ecl and Law-Bs implies that different portions of deeply subducted oceanic crust may store significantly different H2O contents, depending on bulk-rock chemical composition. In addition, thermodynamic modelling of phase equilibria indicates that the occurring progressive dehydration reactions, which are significantly depending on bulk-rock chemical composition, strongly influence rock densification and eclogite formation in subducting slabs.
ISSN: 0263-4929

hal-00617768
https://hal.archives-ouvertes.fr/hal-00617768
DOI : 10.1111/j.1525-1314.2011.00931.x

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Detailed structural and petrological mapping in the Beni Bousera peridotite (Rif Belt, northern Morocco) shows that this orogenic peridotite massif is composed of four tectono-metamorphic domains with consistent kinematics, marked by a pervasive, shallowly dipping foliation with a NW-SE stretching lineation that progressively rotates towards a NNE-SSW orientation in the lowermost part of the massif. From top to bottom, these domains are garnet-spinel mylonites, Ariègite subfacies fine-grained porphyroclastic spinel peridotites, Ariègite-Seiland subfacies porphyroclastic, and Seiland subfacies coarse-porphyroclastic to coarse-granular spinel peridotites. Microstructures and crystal preferred orientations point to deformation dominantly by dislocation creep in all domains, but the continuous increase in average olivine grain size indicates decreasing plastic work rates from top to bottom. This evolution in deformation conditions is consistent with the change in synkinematic pressure and temperature conditions, from 900°C at 2*0 GPa in garnet-spinel mylonites to 1150°C at 1*8 GPa in the Seiland domain. A pervasive diffuse dunitic-websteritic layering subparallel to the foliation suggests deformation in the presence of melt in the Seiland domain. Gravitational instabilities owing to local melt accumulation may account for <200 m wide areas exhibiting a vertical lineation in this domain. To account for the consistent kinematics and the tectono-metamorphic evolution, which implies a temperature gradient of c. 125°C km−1 preserved across the Beni Bousera massif, we propose that the entire massif records the functioning of a low-angle shear zone, a few kilometres wide, which accommodated exhumation of the base of the lithosphere from ∼90 to ∼60 km depth. Partial melting in the Seiland domain may be explained by fast decompression of the footwall, without the need for exotic heat sources. Moreover, if the present-day orientation of the shear zone is similar to that when it was active in the mantle, the stretching lineations at high angle to the metamorphic gradient imply that shearing parallel to the trend of the belt accompanied thinning; that is, a transtensional deformation of the margin.
ISSN: 0022-3530

hal-00950056
https://hal.archives-ouvertes.fr/hal-00950056
DOI : 10.1093/petrology/egt067

Éditeur(s) : HAL CCSD
Résumé :   Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, 97387 Kourou, Guyane (France) Diplôme : Master Recherche
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
The gravitropic reaction is a fundamental phenomenon in the life of the young trees in under-storey of a tropical rain forest. It enables them to preserve a growth in height even after a fall of remains or a wind fallen wood had leaning them. This reaction passes mainly by the differentiation of reaction wood and the offsetting of the radial growth. The gravitropic reaction is also under the control of various parameters such as the diameter of the stems, the hardness of wood, or masses they carried. The tropical rain forest contains a great specific diversity and ecological strategies. In this work we seek to know if this diversity is reflected in the strategies of recovery of the species in particular on a level of efficiency of reaction. We compared eight species of tropical rain forest with various ecological behaviours. We studied their changes in form in the course of time, as to their growth. We showed that there are indeed interspecific differences in the gravitropic reaction. Some behaviours are specific to some species. We also showed that for the majority of the species, the deformation energy is strongly correlated with the relative growth of the species.
Le redressement gravitropique est un phénomène fondamental dans la vie des jeunes arbres en sous-bois de forêt tropicale. Il leur permet de conserver une croissance en hauteur même après avoir subi la chute de débris ou même un chablis ayant conduit à leur inclinaison. Ce redressement passe principalement par la différentiation de bois de réaction et l’excentrement de la croissance radiale. Le redressement gravitropique est également sous le contrôle de différents paramètres tels que le diamètre des tiges, la dureté du bois, ou les masse portées. La forêt tropicale humide contient une grande diversité spécifique et de stratégies écologiques. Dans ce travail nous cherchons à savoir si cette diversité se reflète dans les stratégies de redressement des espèces notamment au niveau de l’efficience de la réaction. Nous avons comparé huit espèces de forêt tropicale humide avec différents comportements écologiques. Nous avons étudié leurs changements de forme au cours du temps, ainsi que leur croissance. Nous avons réussi à montrer qu’il existe effectivement des différences interspécifiques de redressement. Des comportements particuliers à certaines espèces ont pu être dégagés. Nous avons également montré que pour la majorité des espèces, l’énergie de déformation est fortement corrélée à la croissance relative de l’espèce.
https://hal.archives-ouvertes.fr/hal-01189172

hal-01189172
https://hal.archives-ouvertes.fr/hal-01189172
PRODINRA : 11396

Résumé : Les espaces naturels protégés sont aujourd’hui à l‘échelle mondiale l’une des principales politiques publiques mises en œuvre pour faire face à la destruction des écosystèmes. Leur nombre a beaucoup augmenté ces dernières années et les modes d’action qu’ils recouvrent se sont considérablement diversifiés. Pour autant, les écosystèmes continuent à se dégrader, et l’efficacité de ces dispositifs est souvent remise en cause. Cette thèse vise à analyser les facteurs influant sur l’efficacité des espaces protégés pour la conservation d’écosystèmes amazoniens encore peu dégradés. Elle étudie pour cela la mise en œuvre de dispositifs relevant de doctrines de gestion de l’environnement différentes, basées sur (i) la limitation réglementaire maximale des activités humaines impactantes pour les écosystèmes, (ii) la gestion des ressources par des populations locales ou traditionnelles ou (iii) la mise en place d’une gestion forestière durable sur des terres publiques. Nous nous plaçons dans une posture comparative entre la Guyane (France) et l’Amapá (Brésil), territoires partageant une frontière commune, principalement matérialisée par le fleuve Oyapock. La comparaison internationale entre ces deux régions présentant une couverture exceptionnelle en espaces protégés, dans des conditions écologiques et géographiques relativement similaires, nous permet d’observer l’influence du contexte historique et sociopolitique sur les modes de prise en charge de la gestion de l’environnement par les aires protégées. Nous nous sommes basés sur une approche constructiviste, appuyée sur une production de données principalement qualitatives (entretiens semi-directifs, analyse de documents, observation participante…). Nous avons ainsi procédé à une déconstruction critique des dispositifs « aires protégées », permettant de mettre en lisibilité les enjeux environnementaux qu’ils portent, et d’analyser l’efficacité environnementale des stratégies mises en œuvre. Cette analyse s’est articulée autour d’une lecture à la fois diachronique et multiscalaire des processus de gestion.Nous montrons que la mise en place des espaces protégés de Guyane et d’Amapá a été portée par des coalitions d’acteurs structurées autour de doctrines de gestion, c’est à dire de conceptions partagées des conditions de mise en œuvre d’une « bonne gestion environnementale ». Les dispositifs créés ont hérité des ressources stratégiques d’action et de la légitimité de ces coalitions. Les coalitions porteuses de la création des espaces protégés en Amapá sont fortement articulées aux mouvements sociaux et environnementaux plus généraux de l’Amazonie brésilienne, notamment pour les revendications socio-environnementales émergeant à la sortie de la période dictatoriale. En Guyane française, les espaces naturels protégés sont principalement la résultante de compromis entre d’une part une volonté d’exemplarité de l’action de la France en Amazonie, et d’autre part une recherche de minimisation des conflits avec les acteurs politiques locaux.
Nowadays, natural protected areas are one of the main public policies implemented at the international level in order to prevent the destruction of ecosystems. During the last decades, they became very numerous, and mobilized more and more diversified modes of action. However, natural ecosystems continue to deteriorate, and the effectiveness of protected areas is often questioned. The aim of this thesis was to analyse the factors influencing the effectiveness of protected areas in a context of Amazonian ecosystems that are still well preserved. We observed the implementation of environmental management arrangement (protected areas) that are based on various doctrines: (i) the strong limitation of all harmful human activities through legislation; (ii) the management of resources by local or traditional populations; and (iii) the implementation of sustainable forest management on public lands. We adopted a comparative approach between Guyana (France) and Amapá (Brazil), territories that share a common border, mainly identifiable by the Oyapock River. These two territories present quite similar ecological and geographical conditions, and both have an exceptional coverage of protected areas. Therefore this international comparison allowed us to observe the influence of the historical and socio-political context on the implementation of protected areas. We used a constructivist approach, mainly based on qualitative data (semi-structured interviews, document analysis, participant observation...). We effected a critical deconstruction of "protected areas" management arrangements in order to make their environmental objectives intelligible, and we analysed the environmental effectiveness of the strategies implemented. This analysis was based on a diachronic and multiscalar lecture of management processes. We show that the establishment of protected areas in Guiana and Amapá was led by coalitions of actors structured around management doctrines, i.e. shared conceptions of "good environmental management". Management arrangements created inherited the strategic resources of action and the legitimacy of these coalitions. In Amapá, coalitions were strongly articulated with wider social and environmental movements of the Brazilian Amazon, especially in the case of socio-environmental claims rising at the end of the dictatorship. In French Guiana, the natural protected areas are mainly the result of compromise between the French willingness to serve as an example in the Amazon region, and the minimisation of conflicts with local politicians.

http://www.theses.fr/2014AGUY0744/document

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper deals with a comparison of different colour space in order to improve high resolution images classification. The background of this study is the measure of the agriculture impact on the environment in islander context. Biodiversity is particularly sensitive and relevant in such areas and the follow-up of the forest front is a way to ensure its preservation. Very high resolution satellite images are used such as QuickBird and IKONOS scenes. In order to segment the images into forest and agriculture areas, we characterize both ground covers with colour and texture features. A classical unsupervised classifier is then used to obtain labelled areas. As features are computed on coloured images, we can wonder if the colour space choice is relevant. This study has been made considering more than fourteen colour spaces (RGB, YUV, Lab, YIQ, YCrCs, XYZ, CMY, LMS, HSL, KLT, IHS, I1I2I3, HSV, HSI, etc.) and shows the visual and quantitative superiority of IHS on all others. For conciseness reasons, results only show RGB, I1I2I3 and IHS colour spaces.
SPIE Remote Sensing Proceedings
Cardiff, United Kingdom

hal-00602277
https://hal.archives-ouvertes.fr/hal-00602277

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The temperate symbiotic sea anemone Anemonia viridis, a member of the Cnidaria phylum, is a relevant experimental model to investigate the molecular and cellular events involved in the preservation or in the rupture of the symbiosis between the animal cells and their symbiotic microalgae, commonly named zooxanthellae. In order to increase research tools for this model, we developed a primary culture from A. viridis animal cells. By adapting enzymatic dissociation protocols, we isolated animal host cells from a whole tentacle in regeneration state. Each plating resulted in a heterogeneous primary culture consisted of free zooxanthellae and many regular, small rounded and adherent cells (of 3-5 mu m diameter). Molecular analyses conducted on primary cultures, maintained for 2 weeks, confirmed a specific signature of A. viridis cells. Further serial dilutions and micromanipulation allowed us to obtain homogenous primary cultures of the small rounded cells, corresponding to A. viridis ``epithelial-like cells''. The maintenance and the propagation over a 4 weeks period of primary cells provide, for in vitro cnidarian studies, a preliminary step for further investigations on cnidarian cellular pathways notably in regard to symbiosis interactions.
ISSN: 0920-9069

hal-01546173
https://hal.archives-ouvertes.fr/hal-01546173
DOI : 10.1007/s10616-013-9566-2

Éditeur(s) : HAL CCSD Heldermann
Résumé : International audience
We present an iterative method for finding zeroes of maximal monotone operators in a real Hilbert space. The underlying idea relies upon the discretization of a first order dissipative dynamical system which allows us to preserve the local feature, as well as to obtain convergence results. The main theorems do not only recover known convergence results of standard and inertial proximal methods, but also provide a theoretical basis for the application of new iterative methods.
Journal of Convex Analysis

hal-00780210
https://hal.univ-antilles.fr/hal-00780210

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This article summarizes the geodynamic evolution of the Variscan to Mesozoic Tethyan subduction history, based on a review of geochronological data from Eastern Anatolia and the Lesser Caucasus, and new isotopic ages for the Georgian crystalline basements. The geological history of the basements of Georgia (Transcaucasus) and NE Turkey (eastern Pontides) appears to be similar and provides evidence for a continuously active continental margin above a north-dipping subduction since at least the Lower Jurassic. New La-ICPMS U-Pb ages from the Georgian basement provide further evidence for the derivation of the Transcaucasus and its western continuation (the eastern Pontides) from Gondwana. A migmatized granodiorite provides preserved magmatic zircon cores with an age of 474 ± 3 Ma, while the age of migmatization is constrained by its 343 ± 2 Ma metamorphic rims. Metamorphism is synchronous with widespread I-type granites that were emplaced at 335 ± 8 Ma in the neighbouring Dzirula massif, and in the eastern Pontides. These U-Pb ages are in close agreement with recently obtained Ar/Ar ages from biotites and muscovites from metamorphic schists and U-Pb ages ranging from 340 to 330 Ma in the Georgian basement. The narrow range of ages suggests that the Variscan LP-HT metamorphic event in the eastern Pontides and Georgia was of short duration and likely related to mantle-derived intrusives. Furthermore, we suggest that (1) rifting of the Pontides-Transcaucasus block (PTB) from Gondwana at 450–350 Ma could have been driven by roll-back of the south-dipping Rheic slab, (2) that the main metamorphic and coeval magmatic events are related to the accretion of the PTB to the Eurasian margin at c. 350 Ma, while the source of magmatism is ascribed to slab detachment of the south-dipping slab at 340 Ma and that (3) three subduction zones may have been contemporaneously active in the Tethyan domain during the Jurassic: (i) the Lesser Caucasus South Armenian Block (SAB) shares a similar Gondwana affinity, but bears younger ages for its MP-MT metamorphic evolution and calc-alkaline magmatism bracketed from 160 to 123 Ma; (ii) north-dipping subduction below the PTB from c. 210 Ma to 150 Ma; (iii) northward intra-oceanic subduction bracketed from 180 to 90 Ma between the SAB and the PTB.
ISSN: 0264-3707

hal-01347761
https://hal.archives-ouvertes.fr/hal-01347761
DOI : 10.1016/j.jog.2016.03.003

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We have analyzed shear wave splitting recorded by portable and permanent broadband and long-period stations located in the eastern United States. Teleseismic shear waves (SKS, SKKS, and PKS) were used to retrieve the splitting parameters: the orientation of the fast wave polarization plane ϕ and the delay time δt. In total, 120 seismic events were processed, allowing for more than 600 splitting measurements. Within the Appalachians, stations located in the western (external) part are characterized by δt≈1s and ϕ trending N50°– 70°E in the south and central regions and N30°–40°E in the north, closely following the trend of the orogenic belt in these areas. The transition region between north and central is characterized by δt≈1–1.3 s and by E-W trending ϕ that are at a high angle to the regional geologic trend. Measurements at two stations located in the eastern (internal) part of the belt indicate very weak anisotropy. The large-scale pattern of anisotropy is not consistent with that predicted for simple asthenospheric flow beneath the plate. Splitting along the southern and eastern margins of the continent is consistent with that expected for Grenvillian deformation, an alternative model of asthenospheric flow around the cratonic keel cannot be ruled out. Within the cratonic core, the correlation between δt and lithospheric thickness suggests a lithospheric anisotropy. Smaller-length-scale variations also argue for a significant contribution of lithospheric structures. The fabric responsible for shear wave splitting may have formed during tectonic episodes that affected the eastern United States, i.e., the Grenville and Appalachian orogenies and the subsequent rifting of the North Atlantic Ocean. Our observations in the western Appalachians suggest that the anisotropy may be preserved since the Grenvillian orogeny. The absence of detectable splitting in the two stations in the eastern Appalachians is attributed to the igneous intrusions related to the Atlantic rifting. The measurements in the transition between the northern and central southern Appalachians, constitute an intriguing anomaly, whose E-W ϕ have little obvious relation to the regional surface geology. We suggest two possible causes: (1) the local dominance of asthenospheric flow, motivated by the proximity of a pervasive low-velocity anomaly and (2) lithospheric deformation in a transcontinental strike-slip fault zone active during the Appalachian collision.
ISSN: 2169-9313

hal-01388859
http://hal.univ-reunion.fr/hal-01388859
http://hal.univ-reunion.fr/hal-01388859/document
http://hal.univ-reunion.fr/hal-01388859/file/Barruol_JGR_1997.pdf
DOI : 10.1029/96JB03800

Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
Coronaviruses (CoVs) have shown neuroinvasive properties in human and animal secondary to replication in peripheral organ but the mechanism of neuroinvasion is unknown. The major aim of our work was to evaluate the ability of CoVs to enter the central nervous system (CNS) through the blood brain barrier (BBB). Using the high hepatotropic mouse hepatitis virus (MHV) type 3, its attenuated variant 51.6-MHV3, showing low tropism for endothelial cells, and the low hepatotropic MHV-A59 strains from murine coronavirus group, we investigated the viral-induced dysfunctions of BBB in vivo and in brain microvascular endothelial cells (BMECs) in vitro. We report here a MHV strain-specific ability to cross the BBB during acute infection according to their virulence for liver. Brain invasion was only observed in MHV3-infected mice and correlated with enhanced BBB permeability associated with decreased expression of ZO-1, VE-cadherin and occludin but not claudin-5 in the brain or in cultured BMECs. BBB breakdown in MHV3 infection was not related to production of barrier-dysregulating inflammatory cytokines or chemokines by infected BMECs but rather to a downregulation of barrier protective IFN-β production. Our findings highlight the importance of IFN-β production by infected BMECs in preserving BBB function and preventing access of blood-borne infectious viruses to the brain. IMPORTANCE: Coronaviruses (CoVs) infect several mammals including humans and are associated with respiratory, gastrointestinal and/or neurological diseases. Some evidences suggest that human respiratory CoVs may show neuroinvasive properties. Indeed, the SARS-CoV, causing severe acute respiratory syndrome, and the CoVs OC43 and 229E were found in the brains of SARS and multiple sclerosis patients respectively. These finding suggest that hematogenous spread CoVs may gain access to CNS at the BBB level. Herein we report for the first time that CoVs exhibit ability to cross the BBB according to strain virulence. BBB invasion by CoVs correlates with viral-induced disruption of tight junctions on BMECs, leading to BBB dysfunction and enhanced permeability. We provide evidence that production of IFN-β by BMECs during CoV infection may prevent BBB breakdown and brain viral invasion
ISSN: 0022-538X

hal-01187308
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01187308
DOI : 10.1128/JVI.01501-15
PUBMED : 26202229

Éditeur(s) : HAL CCSD
Résumé : In the bay of Aigues-Mortes, the managers of the co astal cities try to preserve the socio-economic and patrimonial stakes against the coastal hazards, such as contamination, storm surge and erosion. In this context, a massive beach nourishment of sand (1 million of m3 for 10km of coastline) was made at the beginning of year 2008 to reduce erosion. The REPBAM project (REchargements et Panaches sédiment aires dans la Baie d'Aigues-Mortes) aims to qualify and quantify by in-situ measurements and numerical modelling: 1. the geomorphological evolution of this modified coast and 2. the impact of the sediment's resuspension on the coastal ecosystems, in particular the one of the Posidonia oceanica seagrass. A numerical modelling "wave/current/sediment" is first implemented for December 2008. Nested and curvilinear grids allow a very high resolution for the beach area but also include the inner shelf where the seagrasses are located. Hydrodynamic and topo-bathymetric measurements were acquired from January to May 2012. Model and measurements results show the same trends during storms: strong currents, seaward migrationof the innerbar, sediment resuspension and turbid on the inner shelf.
Coastal Dynamics 2013
Arcachon, France

hal-00908082
https://hal.archives-ouvertes.fr/hal-00908082

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
In the Tifnoute Valley, three plutonic units have been defined: the Askaoun intrusion, the Imourkhssen intrusion and the Ougougane group of small intrusions. They are made of quartz diorite, granodiorite and granite and all contain abundant mafic microgranular enclaves (MME). The Askaoun granodiorite and the Imourkhssen granite have been dated by LA-ICP-MS on zircon at 558 ± 2 Ma and 561 ± 3 Ma, respectively. These granitic intrusions are subcontemporaneous to the widespread volcanic and volcano-detrital rocks from the Ouarzazate Group (580-545 Ma), marking the post-collisional transtensional period in the Anti-Atlas and which evolved towards alkaline and tholeiitic lavas in minor volume at the beginning of the Cambrian anorogenic intraplate extensional period. Geochemically, the Tifnoute Valley granitoids belong to an alkali-calcic series (high-K calc-alkaline) with typical Nb-Ta negative anomalies and no alkaline affinities. Granitoids and enclaves display positive εNd-560Ma (+0.8 to +3.5) with young Nd-TDM between 800 and 1200 Ma and relatively low 87Sr/86Sr initial ratios (Sri: 0.7034 and 0.7065). These values indicate a mainly juvenile source corresponding to a Pan-African metasomatized lithospheric mantle partly mixed with an old crustal component from the underlying West African Craton (WAC). Preservation in the Anti-Atlas of pre-Pan-African lithologies (c. 2.03 Ga basement, c. 800 Ma passive margin greenschist-facies sediments, allochthonous 750-700 Ma ophiolitic sequences) indicates that the Anti-Atlas lithosphere has not been thickened and was never an active margin during the Neoproterozoic. After a transpressive period, the late Ediacaran period (580-545 Ma) is marked by movement on near vertical transtensional faults, synchronous with the emplacement of the huge Ouarzazate Group and the Tifnoute Valley granitoids. We propose here a geodynamical model where the Tifnoute Valley granitoids as well as the Ouarzazate Group were generated during the post-collisional metacratonic evolution of the northern boundary of the West African craton. The convergence with the peri-Gondwanan active margin produced brittle fracturing of the cratonic boundary without thickening, allowing rising of magmas. The Tifnoute Valley granitoids display a metasomatized lithospheric mantle source mixed with a minor ancient (2 Ga) continental crust component from the underlying WAC.
ISSN: 0930-0708

halsde-00782152
https://hal.archives-ouvertes.fr/halsde-00782152
DOI : 10.1007/s00710-012-0245-3

Éditeur(s) : HAL CCSD Editions de la maison des sciences de l'Homme
Résumé : International audience
En 2000, deux gisements préservés de façon exceptionnelle étaient découverts sur l'arrière-plage de Baie Orientale à Saint-Martin, une île des Petites Antilles : des campements du Mésoindien (800 av. J.-C - 100 ap. J.-C.) associant activités de subsistance et fabrication d'outils sur pierre, coquille ou corail, ce qui est sans précédent pour la période précéramique, et une occupation du Néoindien récent (740-960 ap. J.-C.) interprétée comme un campement spécialisé, satellite du village de Pointe du Canonnier, selon un schéma d'occupation du territoire caractéristique de cette période. L'étude à la fois novatrice et originale que nous en propose Dominique Bonnissent, nous permet d'accéder au mode de vie complexe des populations précéramiques nomades qui ont sillonné la mer Caraïbe, et fait de cet ouvrage une ressource incontournable pour l'archéologie précolombienne caribéenne. En tête de chaque chapitre, un résumé avec références bibliographiques et renvois aux figures permettra aux lecteurs de langue anglaise et espagnole d'accéder aux données essentielles de la démonstration. Ces deux chapitres traitent de la caractérisation et de l'origine de la matière première lithique utilisée par ces deux groupes d'occupants
Les gisements précolombiens de la Baie Orientale. Campements du Mésoindien et du Néoindien sur l'île Saint-Martin (Petites Antilles)

ISBN : 978-2-7351-1124-4
hal-00989501
https://hal.archives-ouvertes.fr/hal-00989501

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy A1 - Oxford Open Option C
Résumé : International audience
BACKGROUND: Infections of renal grafts with Candida species can induce life-threatening complications in the recipient. METHODS: A 9-year retrospective study involving all of the transplant centers in France was designed to determine the incidence, origin, characteristics, and outcome of graft-site candidiasis that occurred after kidney transplantation. Yeasts cultured from preservation or drainage solutions and graft specimens were recorded. RESULTS: Among 18,617 kidney grafts, 18 recipients corresponding to 12 donors developed culture-confirmed graft-site candidiasis (incidence, 1 case per 1000 grafts) a median of 25 days after the graft procedure. Clinical presentations included 14 cases of renal arteritis (13 were complicated by aneurysm), 1 urinoma, 2 graft site abscesses, and 1 surgical site infection. Candida albicans was involved in 13 cases. A unique C. albicans genotype or a single rare Candida species was involved in each episode. Together with the clinical history, these findings demonstrate that organ contamination followed by transmission to the recipient occurred during recovery. Therapeutic management varied from simple monitoring in 1 case to a combination of surgery (nephrectomy in 9 cases and arterial bypass in 9 cases) and antifungal therapy (14 cases). Overall, 3 of 18 kidney transplant recipients died, and 9 had their graft surgically removed. CONCLUSION: Graft-transmitted candidiasis that ends most often in fungal arteritis is associated with high morbidity and mortality after kidney transplantation and is related to organ contamination during recovery in the donor.
Clinical Infectious Diseases

hal-00676313
https://hal.archives-ouvertes.fr/hal-00676313
DOI : 10.1086/595688
PUBMED : 19090753

Éditeur(s) : HAL CCSD
Résumé : 1 page
The main aim of this study, co-funded by BRGM, Regional Council of Guadeloupe, European Union, ADEME and UAG, was to examine the silica deposition mechanisms and estimate their deposition kinetics at acidic and basic pH conditions, during the cooling from 260 to 25°C of separated waters, discharged from production wells, located in the Bouillante geothermal field. The acquisition of this type of information is very useful not only for the geothermal exploitation but especially, if production fluids are re-injected in the ground, as this is envisaged in the Bouillante geothermal field. The different on site experiments showed that, in these conditions, the silica deposition was always initiated by a silica polymerization mechanism and the formation of a white colloidal gel, which slowed down the silica precipitation. In agreement with the literature data, this polymerization mechanism is characterized by an order 2 kinetic law, strongly dependant on pH. The determination of the specific surface area by specific mercury porosimetry for this gel (250 m2/g) in the UAG laboratories, allowed estimating the corresponding kinetic constant at 25°C. Other experiments at different final temperatures (50, 75 and 100°C) are necessary in order to define this constant as a function of the temperature. The silica precipitation under amorphous silica form was observed much later, after the polymerization stage, and only in particular conditions (long time of atmospheric exposure, water stagnation...). The pH of the Bouillante geothermal fluid is estimated to be close to 5.3±0.3, at 260°C, in the reservoir conditions. If this parameter, very influent on the kinetics of silica deposition, can be preserved at values less than 7 during the re-injection of the production fluids in the ground at relatively high temperatures (150-160°C), it is strongly probable that no chemical treatment is necessary to avoid silica precipitation.
19ème Conférence Géologique de la Caraïbe - 2011
Gosier, Guadeloupe, France

hal-00575943
https://hal-brgm.archives-ouvertes.fr/hal-00575943