Éditeur(s) : HAL CCSD
Résumé : The coastal intrusion of brine threatens populations. This is particularly prejudicial in carbonate environments. We have studied the Miocene coral reef of S-E Majorca for better understanding the relation between geological structure and intrusion. For that purpose, we have used multi-scalar and multi-disciplinary methods. The measurements in 25 boreholes over the whole coral platform have allowed defining the stratigraphic structure and some elements of the regional tectonic. The reef progrades in the NE-SW direction, starting from the Aquitanian to terminates at the Messinian. The Messinian Salinity Crisis involves a disappearance of the Mediterranean corals and results in a Terminal Carbonate Complex which overlays a great part of the previously living corals of Majorca. At the experimental site scale, the study of the mineral composition, the texture, and the diagenesis have allowed characterization of the carbonate sequence heterogeneity. Layers of mineralization accompanied by dolomitization and low porosity correspond to postdepositional eustatic levels. The causes for the existence and the orientation of fractures are studied. The permeability to porosity relation is approached. The porosity structure is studied by comparison between primary and secondary porosity. This study contributes to the knowledge of the world best documented site for the evolution of carbonate reef reservoirs, with applications for brine intrusion and for hydrocarbon extraction.
Les intrusions d'eau salée en zone côtière constituent une menace pour la population. Celles-ci sont particulièrement dommageables en contexte carbonaté. Nous avons étudié le récif corallien Miocène du sud-est de Majorque afin de comprendre la relation entre structure géologique et intrusion. Pour cela nous avons utilisé des méthodes multi-scalaires et multi-disciplinaires. Les mesures dans 25 forages sur l'ensemble de la plateforme corallienne ont permis de préciser la structure stratigraphique et certains éléments de la tectonique régionale. Le récif prograde dans la direction NE-SO, en partant de l'Aquitanien pour aboutir au Messinien. La Crise de Salinité Messinienne entraîne une disparition des coraux méditerranéens et se traduit par un Complexe Carbonaté Terminal qui s'étend sur une grande partie des coraux autrefois vivants de Majorque. A l'échelle du site expérimental, l'étude de la composition minérale, de la texture et de la diagenèse ont permis de caractériser l'hétérogénéité de la séquence carbonatée. Des couches de minéralisation accompagnées de dolomitisation et de faible porosité correspondent à différents niveaux eustatiques post-dépositionnels. Les causes de l'existence et de l'orientation des fractures sont étudiées. La relation de perméabilité à porosité est précisée. La structure de porosité est étudiée par comparaison entre la porosité primaire et la porosité secondaire. Cette étude contribue à la connaissance du site le mieux documenté au monde pour l'évolution des réservoirs carbonatés récifaux, avec applications pour les intrusions d'eau salée et l'extraction des hydrocarbures.
https://tel.archives-ouvertes.fr/tel-00440019

tel-00440019
https://tel.archives-ouvertes.fr/tel-00440019
https://tel.archives-ouvertes.fr/tel-00440019/document
https://tel.archives-ouvertes.fr/tel-00440019/file/thesemariasube.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Experimental modelling applied to the study of orogenic wedge dynamics has been a subject of fruitful research for more than 30 years, although the technique dates back as far as the early XIXth century. On one hand, several first order parameters controlling the structural evolution of mountain belts have been intensively investigated using the classic tectonic "sandbox" models. The main parameters are the properties of the basal décollement, the deforming material, the backstop, and fluxes, kinematics and surface processes. On the other hand, the morphological evolution of a mountain relief subjected to changing tectonic or climatic forcing has been addressed using another kind of approach called "geomorphic" models. Nowadays, the literature is extremely rich, particularly for the sandbox technique, so that it becomes difficult to have an exhaustive view of the effects of the above parameters on mountain evolution. In this article, we propose a detailed review of the main results obtained using both "tectonic" and "geomorphic" approaches. Our goal is to provide an almost complete state-of-the-art in the experimental study of relief dynamics to guide present and future researchers in their understanding of mountain belt evolution.
ISSN: 0040-1951

hal-00757713
https://hal.archives-ouvertes.fr/hal-00757713
DOI : 10.1016/j.tecto.2012.01.027

Éditeur(s) : HAL CCSD
Résumé : In order to minimize CO2 atmospheric concentration, a solution consists in sequestrating CO2 in geological reservoirs. To estimate long term risks, it is necessary to quantify the couplings between reaction processes as well as structural and hydrodynamical modifications. We realised two experimental benches enabling injecting CO2-enriched-brine in conditions corresponding to in situ storage (T < 200 oC and P < 200 bar) and developed
an experimental protocol using X-Ray microtomography and fluid and rock analyses in order to measure the variations of physical and chemical parameters.
The study of carbonated reservoirs near the injection well, allows quantifying different k-phi relationships depending on the dissolution processes and triggered by the local fluid chemical composition and initials conditions. Away from the injection well, we observe carbonate precipitation decreasing the permeability. The study of fracturated caprock samples shows that alternative percolation of CO2-enriched-brine and CO2 gas increases the fracture permeability.
The study of silicated rocks indicates carbonate precipitation in zeolite sandstone and sintered dunite grains. Nevertheless, in zeolite sandstone we also observe the precipitation of clay particles located in the uid pathways which decrease strongly the permeability.
Afin de minimiser la concentration en CO2 dans l'atmosphère une solution consiste à le séquestrer dans les réservoirs géologiques. Pour évaluer les risques à long terme, il est nécessaire de quantifier les couplages entre les processus réactionnels et les modifications structurales et hydrodynamiques. Dans cette optique, nous avons construit deux dispositifs expérimentaux permettant d'injecter des saumures chargées en CO2 dans les conditions de stockage (T < 200 °C et P < 200 bar) et mis en oeuvre un protocole expérimental utilisant la microtomographie RX et l'analyse des roches et des fuides pour quantifier les variations des paramètres physiques et chimiques. Dans le cas des réservoirs carbonatés, on observe, près du puits d'injection, une forte variabilité des relations k-phi en fonction du régime de dissolution contrôlé par la chimie locale du fluide, ainsi que par les conditions initiales. A plus grande distance, on observe des processus de précipitation diminuant fortement la perméabilité. L'étude des roches de couverture fracturées (argilite) a montré qu'une percolation alternée d'une saumure chargée en CO2 et de CO2 gaz augmentait la perméabilité de fracture. Dans le cas des roches silicatées, la précipitation de carbonates est mise en évidence aussi bien dans les grès à zéolites que dans les frittés de dunite de San Carlos. Cependant, dans les grès à zéolites, la précipitation d'une phase argileuse est observée dans les chemins d'écoulement et engendre une forte diminution de la perméabilité.
https://tel.archives-ouvertes.fr/tel-00416408

tel-00416408
https://tel.archives-ouvertes.fr/tel-00416408
https://tel.archives-ouvertes.fr/tel-00416408/document
https://tel.archives-ouvertes.fr/tel-00416408/file/These_Luquot.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A detailed rock-magnetic and archeointensity study was carried out on materials baked by a western Mexican artisan following traditional techniques to produce faithful reproductions of archeological pieces of the Michoacan region (Western Mesoamerica). The field strength at the site (41.0 +/- 0.51 mu T) was measured with a fluxgate magnetometer and the temperature of the furnace during the baking process was monitored continually by means of a thermocouple placed in the middle of the baking cavity.;Rock-magnetic experiments performed on the raw material (clay and paste) and on in situ prepared baked ceramics and bricks included measurement of thermomagnetic curves (susceptibility and strong-field magnetization versus temperature), first-order reversal curves (FORC), anisotropy of magnetic susceptibility (AMS) and anisotropy of thermoremanent magnetization (A-TRM). Magnetite and probably hematite are present in the samples as carriers of the remanence. Hysteresis ratios suggest that the samples fall in the pseudo-single-domain grain size region, which may indicate a mixture of multidomain and a significant amount of single-domain grains.;Ceramic pieces and brick fragments were subjected to the Thellier-Coe archeointensity method and to an alternative paleointensity experiment, with a TRIAXE magnetometer, in order to check whether they are faithful recorders of the local geomagnetic field strength.;Mean raw-intensity of sample M1 (pottery) overestimates a 7% the expected site intensity, while those corresponding to the brick samples (LQ1 and LQ2) underestimate it 15%. Brick sample LNQ shows a slightly lower intensity (7%), but agrees with the expected site intensity within the experimental uncertainty. The intensity retrieved from the volcanic fragment also included closely reproduces the expected intensity. After A-TRM and cooling-rate corrections, all mean raw values move closer to the expected intensity.;Measurement of temperatures at different parts inside the kiln (bottom and upper parts of both central and peripheral parts) revealed the existence of significant thermal gradients, similar to those observed in ovens from other localities. Different cooling rates are then expected in a single oven.;The scatter in the intensity determinations observed in this study, retrieved from pieces elaborated together in the same oven, could arise from this differentiated cooling rate within the oven and thus, to an inappropriate cooling rate correction in the archeointensity protocol. As this situation was probably reproduced in the baking of ancient ceramic artifacts, a better knowledge of the temperature distribution inside these types of kiln would be desirable in order to choose the appropriate cooling rate correction.
ISSN: 0031-9201

hal-00644559
https://hal.archives-ouvertes.fr/hal-00644559
DOI : 10.1016/j.pepi.2011.06.007

Éditeur(s) : Springer
Résumé : Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r (2) = 0.91, n = 12, p < 0.0001) to bacterial production, making this value a good predictor of active cell dynamics along the study. While confinement and temperature were the two principal experimental factors affecting bacterial community composition and dynamics, respectively, additions of freshwater viruses had significant effects on coastal bacterial communities. Thus, foreign viruses significantly reduced net bacterial population increase as compared to the enrichment treated with inactivated virus. Moreover, freshwater viruses recurrently and specifically affected bacterial community composition, as compared to addition of autochthonous viruses. In most cases, the combined treatment viruses and freshwater dissolved organic matter helped to maintain or even enhance species richness in coastal bacterial communities in agreement to the 'killing the winner' hypothesis. Thus, riverine virus input could potentially influence bacterial community composition of the coastal bay albeit with modest modification of bulk bacterial growth.
Microbial Ecology (0095-3628) (Springer), 2009-02 , Vol. 57 , N. 2 , P. 295-306

Droits : 2009 Springer
http://archimer.ifremer.fr/doc/2009/publication-6636.pdf
DOI:10.1007/s00248-008-9428-1
http://archimer.ifremer.fr/doc/00000/6636/

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : International audience
Replenished axial melt lenses at fast-spreading mid-oceanic ridges may move upward and intrude into the overlying hydrothermally altered sheeted dikes, resulting in high-grade contact metamorphism with the potential to trigger anatexis in the roof rocks. Assumed products of this process are anatectic melts of felsic composition and granoblastic, two-pyroxene hornfels, representing the residue after partial melting. Integrated Ocean Drilling Program Expeditions 309, 312, and 335 at Site 1256 (eastern equatorial Pacific) sampled such a fossilized oceanic magma chamber. In this study, we simulated magma chamber roof rock anatectic processes by performing partial melting experiments using six different protoliths from the Site 1256 sheeted dike complex, spanning a lithological range from poorly to strongly altered basalts to partially or fully recrystallized granoblastic hornfels. Results show that extensively altered starting material lacking primary magmatic minerals cannot reproduce the chemistry of natural felsic rocks recovered in ridge environments, especially elements sensitive to hydrothermal alteration (e.g., K, Cl). Natural geochemical trends are reproduced through partial melting of moderately altered basalts from the lower sheeted dikes. Two-pyroxene hornfels, the assumed residue, were reproduced only at low melting degrees (<20 vol%). The overall amphibole absence in the experiments confirms the natural observation that amphibole is not produced during peak metamorphism. Comparing experimental products with the natural equivalents reveals that water activity (aH2O) was significantly reduced during anatectic processes, mainly based on lower melt aluminum oxide and lower plagioclase anorthite content at lower aH2O. High silica melt at the expected temperature (1000–1050 °C; peak thermal overprint of two-pyroxene hornfels) could only be reproduced in the experimental series performed at aH2O = 0.1.
ISSN: 0010-7999

hal-01174139
https://hal.archives-ouvertes.fr/hal-01174139
DOI : 10.1007/s00410-015-1136-5

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Rheological properties of mantle minerals and rocks at temperatures (T) appropriate to much of Earth's lithosphere have remained poorly constrained, even though past experimental studies on olivine single crystals and polycrystalline aggregates have quantified the high-temperature creep mechanisms (T > 1200 degrees C). Consequently, we have performed deformation experiments on crystals of San Carlos olivine at lower temperatures, from 900 degrees to 1200 degrees C, in triaxial compression along the [101](c) direction. The experiments were carried out at a confining pressure of 300 MPa in a high-resolution gas-medium mechanical testing apparatus at differential stresses of 100 to 500 MPa. Several samples were deformed at constant displacement rate and others at constant load, in order to provide insight into possible effects of work-hardening. Under the deformation conditions investigated, little evidence of work-hardening was observed. The data follow a power-law dependence on stress, as in previous high-temperature deformation studies. The samples were, however, considerably weaker than predicted by the experimentally determined high-temperature constitutive equation for olivine crystals of this orientation from the study of Bai et al. (1991). The mechanical behavior correlates instead with the weaker of the two mechanisms (flow laws) that contribute to the high-temperature constitutive equation. Thus, our experiments demonstrate that published high-temperature constitutive equations overestimate the strength of lithospheric mantle and that the transition to low-temperature creep occurs at lower temperatures than previously inferred. Citation: Demouchy, S., S. E. Schneider, S. J. Mackwell, M. E. Zimmerman, and D. L. Kohlstedt (2009), Experimental deformation of olivine single crystals at lithospheric temperatures, Geophys. Res. Lett., 36, L04304, doi: 10.1029/2008GL036611.
ISSN: 0094-8276

hal-00420070
https://hal.archives-ouvertes.fr/hal-00420070
DOI : 10.1029/2008GL036611

Éditeur(s) : HAL CCSD Publisher : Baltimore : Williams & Wilkins, c1950-. Latest Publisher : Bethesda, MD : American Association of Immunologists
Résumé : International audience
Hepatic periportal fibrosis, which affects 5–10% of subjects infected by Schistosoma mansoni, is caused by the T cell-dependent granuloma that develop around schistosome eggs. Experimental models of infection have shown that granuloma and fibrosis are tightly regulated by cytokines. However, it is unknown why advanced periportal fibrosis occurs only in certain subjects. The goal of the present study was to evaluate the cytokine response of S. mansoni-infected subjects with advanced liver disease in an attempt to relate susceptibility to periportal fibrosis with an abnormal production of cytokines that regulate granuloma and fibrosis. Fibrosis was evaluated by ultrasound on 795 inhabitants of a Sudanese village in which S. mansoni is endemic: advanced periportal fibrosis was observed in 12% of the population; 35% of the affected subjects exhibited signs of portal hypertension. Age (odds ratio (OR), 11.5), gender (OR, 4.2), and infection levels (OR, 2.2) were significantly (p < 0.01) associated with hepatic fibrosis. Cytokines produced by egg-stimulated blood mononuclear cells from 99 subjects were measured (75 with no or mild fibrosis; 24 subjects with advanced fibrosis). Multivariate analysis of cytokine levels showed that high IFN-γ levels were associated with a marked reduction of the risk of fibrosis (p = ‫OR, 0.1); in contrast, high TNF-α levels were associated with an increased risk (p = 0.05; OR, 4.6) of periportal fibrosis. Moreover, infection levels were negatively associated with IFN-γ production. These results with observations in experimental models strongly suggest that IFN-γ plays a key role in the protection of S. mansoni-infected patients against periportal fibrosis, whereas TNF-α may aggravate the disease.
ISSN: 0022-1767

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01211587
https://hal.archives-ouvertes.fr/hal-01211587
https://hal.archives-ouvertes.fr/hal-01211587/document
https://hal.archives-ouvertes.fr/hal-01211587/file/929.full.pdf
DOI : 10.4049/jimmunol.169.2.929

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Several studies, both theoretical and experimental, show that sedimentary rocks have a fractal pore-grain interface. In this paper a computer simulated 3-D sedimentary rock structure generated by the Relaxed Ballistic Bidisperse Deposition Model (RBBDM), is investigated to characterize the micro structure of its pores. The pore volume and the rock-pore interface show the same fractal dimension indicating that the pore volume is a fractal. The two point density correlation is computed for the pore space and the results compare favourably with the range reported from experiments. An array of 2-D X-ray tomography micrograph sections of a real sedimentary rock, an oolitic limestone (pure calcite) from the Mondeville formation of Middle Jurassic age (Paris Basin, France), was used to generate a 3-D bitmap. The 3-D real rock sample generated in this manner, was analysed for similar studies as the simulated structure. The results were compared with those obtained from simulation. The simulation results agree qualitatively with the real rock sample. Diffusion through the connected pore space of the simulated structure was studied using a random walk algorithm and the results compared with the similar simulation study done on the 3-D oolitic limestone specimen. In both cases diffusion was found to be anomalous indicating that the sedimentary rock has a fractal geometry. The favourable comparability of results between the simulated and real rock supports the usefulness of the model of sedimentary rock generation which can be applicable to transport phenomena.
ISSN: 0956-540X

hal-00823061
https://hal.archives-ouvertes.fr/hal-00823061
DOI : 10.1093/gji/ggs084

Éditeur(s) : Université des Antilles et de la Guyane
Résumé : Cette étude permet une approche distincte de la réflexion sur les ressources marines dans le cadre d'une aire protégée. En effet, les écosystèmes marins sont essentiels, d’autant plus, qu’ils présentent en Nouvelle-Calédonie une grande richesse, notamment en termes de patrimoine culturel. Ce sont majoritairement les Kanak qui habitent sur la Côte Est de la Province Nord, où la Collectivité et le WWF collaborent à la mise en place de plusieurs aires marines protégées (AMP). Jusqu’à présent, la gestion coutumière Kanak a permis une relative préservation de ces écosystèmes dans un secteur littoral non soumis aux pressions de l’urbanisation, du tourisme ou de la navigation. L’étude s’attache à souligner les enjeux autour de la mise en place des AMP et des perspectives de développement local, sur le milieu marin et les populations locales. Il s’agit de voir comment cette expérimentation est envisagée par les différents acteurs (État, Province Nord, associations, coutumiers etc.) et de s’interroger sur les mécanismes de gouvernance.
This study allows a distinct approach to thinking about the marine resources in a protected area. Indeed, marine ecosystems are essential, especially as they are in New Caledonia, particularly in terms of cultural heritage. It is mainly Kanak who live on the East Coast of the North Province, where the Community and WWF collaborate on the installation of several marine protected areas (MPAs). So far, the Kanak customary management allowed a relative preservation of these ecosystems in a coastal area not subject to the pressures of urbanization, tourism and navigation. The study aims to highlight the issues surrounding the establishment of MPAs and opportunities for local development on the marine environment and local populations. This is to see how this experiment is considered by the various actors (State, Northern Province, associations, etc. customary.) And to consider the mechanisms of governance.

urn:doi:10.4000/etudescaribeennes.4513
http://etudescaribeennes.revues.org/4513

Éditeur(s) : Université de La Rochelle, Ecole doctorale Gay Lussac
Résumé : The thesis work is part of the very current issue on mass mortality outbreaks affecting Pacific oyster, C. gigas, spat and juveniles and questions about the involvement of pesticides in this phenomenon. The first part of this thesis was devoted to study the effects of pesticides on hemocyte parameters in the Pacific oyster (in vitro and in vivo). The immunomodulator effect of selected pesticides (alone or in mixture) has been explored principally through flow cytometry. The second part concerned the study of the effects of a pesticides mixture on OsHV-1 itself. No direct effects have been reported on the viral particles in presence of the pollutants. Moreover, pesticide effects on Pacific oysters were also explored through experimental pathology assays after treatment of animals with a polluant mixture. Results showed that pesticide treated oysters appeared more susceptible to the viral infection in experimental conditions. The third part concerned the study of autophagy in the Pacific oyster, C. gigas. The publication of the complete genome in 2012 has opened up new possibilities for the study of innate immunity in this species. The study of autophagy for the first time in oysters consisted in a first step in the in silico search for genes involved in this pathway and the corresponding proteins by Western blotting. Then, the role of this important process in innate immunity has been explored through reproduction infections tests with or without modulators of autophagy. Results showed that autophagy appeared as involved in defence mechanisms against viral and bacterial infection in Pacific oysters.
Le travail de thèse s’inscrit dans la problématique très actuelle des mortalités massives de naissain et de juvéniles d’huîtres creuses, C. gigas, et des questionnements autour de l’implication des pesticides dans ce phénomène. La première partie de la thèse a été consacrée à l’étude des effets de pesticides sur les capacités hémocytaires de l’huître creuse (in vitro et in vivo). L’effet immunomodulateur des xénobiotiques sélectionnés (seul ou en mélange) a été exploré principalement au travers de la cytométrie en flux. La deuxième partie de la thèse a concerné l’étude des effets d’un mélange de pesticides sélectionnés sur le virus OsHV-1 et l’infection qu’il induit chez l’huître creuse. Les effets des pesticides sur le virus lui-même ont été évalués. Les expériences réalisées non pas permis de mettre en évidence dans les conditions testées, de dégradation des particules virales en présence des polluants. D’autre part, leurs effets sur les huîtres elles-mêmes ont été explorés après traitement des animaux avec un mélange de pesticides lors d’essais de pathologie expérimentale. Il a ainsi pu être montré que des huîtres préalablement comtaminées par un mélange de pesticides à des concentrations retrouvées dans l’environnement semblaient être plus sensibles à l’infection virale. La troisième partie de la thèse a concerné l’étude de l’autophagie chez l’huître creuse, C. gigas. La publication du génome complet de cette espèce en 2012 a ouvert de nouvelles possibilités pour étudier l'immunité innée. L’étude de l’autophagie réalisée pour la première fois chez l’huître creuse a consisté lors d’une première étape en la recherche in silico de gènes impliqués dans cette voie et des protéines correspondantes par western blotting. Puis, le rôle de ce processus important dans l’immunité innée a été exploré au travers d’essais de reproduction d’infections en présence ou non de modulateurs de l’autophagie. Les résultats obtenus semblent montrer que l’autophagie soit un processus important pouvant être impliqué dans les capacités de défense de l’huître creuse vis-à-vis d’infections virales et bactériennes.

Droits : 2014 Université de La Rochelle
http://archimer.ifremer.fr/doc/00226/33740/32149.pdf
http://archimer.ifremer.fr/doc/00226/33740/

Éditeur(s) : Poster présenté au colloque Carribean & Latin American Aquaculture 2007, 6 - 9 novembre 2007, San Juan, Puerto Rico
Résumé : The first aim of this study was to evaluate on a technical basis the rearing of shrimps in floating cages set up in earthen ponds. Shrimps reared in and outside the cages presented comparable growths and survival rates. Then it was concluded that shrimp culture in floating cages did not present zootechnical biases comparing to pond culture. The second objective of this study was to assess the present method as a statistical point of view. We found that for expected differences of 20% to the control mean, 3 and 6 floating cages per treatment will be reasonable to determined statistical differences for growth parameters and survival. Furthermore, we showed a significant pond effect as regard as survival and growth between both sets of cages. This results illustrated the within farm variability among the ponds, and confirmed that specific characteristics of each ponds from a same farm make difficult to use them as experimental unit. The study demonstrates that floating cages rearing is an economical, powerful, and sensitive experimental tool for shrimp culture studies specifically undertaken under close to semi-intensive production conditions.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2007/acte-4100.pdf
http://archimer.ifremer.fr/doc/00000/4100/

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Strain and strain rate partitioning in partially molten rocks are two of the important mechanisms that govern the process of coupling and/or decoupling of the partially molten lithosphere. Consequently, the proportion of partial melt and crystals and their network in partially molten rocks influence the degree of the partitioning along with the bulk rheology of the system. This study explores the possible role of finite strain and strain rate on the rate and volume of partial melting and crystallization in a metapelitic system undergoing deformation. Cylinders of synthetic quartz-muscovite aggregate (7: 3 volume ratio) were deformed in torsion at 750 C, 300 MPa and constant shear strain rate ((gamma) over dot = 3 x 10(-4) s(-1)) for finite shear strains (gamma) 1-15. The deformed samples were studied along the longitudinal tangential ( LT) and axial ( LA) sections to obtain the data along a range of strain rates for a given finite strain and vice versa. The results showed that deformation plays an important role on the kinetics of partial melting and crystallization. With increasing strain rate, amount and rate of crystallization comprise the volumetrically dominant process compared to partial melting at a given finite strain. In contrast, when the strain rate is constant, partial melting is the dominant process over crystallization up to moderate strain (gamma < 5). The dominant process reverses at higher strain, and the system shows more crystallization than partial melting. Application of the experimental data to geological systems implies that for metapelites a significant amount (similar to 20%) of partial melt can generate at high strain rate and moderate strain (gamma similar to 7), but at high strain (gamma = 15) the system is melt depleted. Under such conditions, decoupling should take place in brittle-ductile mode. On the other hand, rocks undergoing deformation with low strain rates and strain (gamma < 3) contain more than 25% partial melt, which can act as a major decoupling agent by localizing ductile shear zones.
ISSN: 0148-0227

hal-00617714
https://hal.archives-ouvertes.fr/hal-00617714
DOI : 10.1029/2010JB007865

Éditeur(s) : PSIC 11 - 11th Pacific Science Inter-Congress : Pacific Countries and their Ocean: Facing Local and Global Changes / 2nd Symposium on French Research in the Pacific. March 2 - 6, 2009 Tahiti, French Polynesia.
Résumé : Experimental infections together with epidemiological studies have shown that pathogenic and non‐pathogenic isolates of V. nigripulchritudo co‐existed in shrimp farm environment (2, 3). Moreover, obtained results also demonstrated that the “summer syndrome”was caused by a single, possibly emerging, cluster of virulent strains. Consequently, it was hypothesized that pathogenic strains of V. nigripulchritudo may persist from one year to the next in the shrimp farm environment and re‐develop inside the grow‐out system at the following rearing cycle (3). This study was therefore aimed at determining whether V. nigripulchritudo isolates may survive, or not, in a shrimp pond bottom soil during a 18‐week drying period. To this end, V.nigripulchritudo mapping was performed with recently developed molecular tools and classical culture‐dependent techniques.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00197/30874/29242.pdf
http://archimer.ifremer.fr/doc/00197/30874/

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : Fire-free forest conversion with organic inputs as an alternative to slash-and-burn could improve agro-ecosystem sustainability. We assessed soil carbon mass changes in a sandy-clayey and well-drained soil in French Guiana after forest clearing by the chop-and-mulch method and crop establishment. At the experimental site of Combi, native forest was cut down in October 2008; woody biomass was chopped and incorporated into the top 20 cm of soil. After about one year of legume and grass cover, three forms of land management were compared: grassland (Urochloa ruziziensis), maize/soybean crop rotation with disk tillage and in direct seeding without tillage. There were four replicates. We measured 14.16 kg m(-2) of carbon in 2 mm-sieved soil down to 2 m depth for the initial forest. Forest clearing did not induce significant soil compaction; neither did any specific agricultural practice. In converted soils, C stocks were measured in the 0-30 cm layer after each crop for three years. Carbon mass changes for soil fractions <2 mm (soil C stock) and >2 mm (soil C pool) in the 0-5, 5-10, 10-20 and 20-30 cm soil layers were assessed on an equivalent soil mass basis. One year and 1.5 years after deforestation, higher C stocks (+0.64 to 1.16 kg C m(-2) yr(-1)) and C pools (+0.52 to 0.90 kg C m(-2) yr(-1)) were measured in converted soils, compared to those of the forest into the top 30 cm of soil. However, the masses of carbon in these converted soils declined later. The highest rates of carbon decrease were measured between 1.5 and 2 years after forest conversion in the <2 mm soil fraction, from 0.46 kg Cm-2 yr(-1) (in grassland soils) to 0.71 kg C m(-2) yr(-1) (in cropland under no tillage). The carbon pool declined during the third year at rates of 0.41 kg C m(-2) yr(-1) (cropland under disk tillage) to 0.76 kg C m(-2) yr(-1) (grassland soils). Three years after forest conversion, C masses in the top 30 cm of soils for grassland showed similar values than for forest. In comparison, the carbon stock in cropped soils managed under no tillage in direct seeding (without mulch) was significantly 17% and 16% lower than in forest and grassland soils, respectively. None of the studied agricultural practices succeeded in accumulating carbon from the chopped forest biomass.
ISSN: 0167-8809

hal-01032438
https://hal.archives-ouvertes.fr/hal-01032438
DOI : 10.1016/j.agee.2013.11.009

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Chlordecone is a persistent organochlorine pesticide that was used in the French West Indies until the early 1990s for banana weevil borer control. Human exposure to this chemical in this area still occurs nowadays due to consumption of contaminated food. Although adverse effects on neurodevelopment, including tremors and memory deficits, have been documented in experimental studies conducted with rodents exposed during the gestational and neonatal periods, no study has been conducted yet to determine if chlordecone alters child development. This study examines the relation of gestational and postnatal exposure to chlordecone to infant development at 18 months of age in a birth-cohort of Guadeloupean children. In a prospective longitudinal study conducted in Guadeloupe (Timoun mother-child cohort study), exposure to chlordecone was measured at birth from an umbilical cord blood sample (n=141) and from a breast milk sample collected at 3 months postpartum (n=75). Toddlers were assessed using an adapted version of the Ages and Stages Questionnaire. Higher chlordecone concentrations in cord blood were associated with poorer fine motor scores. When analyses were conducted separately for boys and girls, this effect was only observed among boys. These results suggest that prenatal exposure to chlordecone is associated with specific impairments in fine motor function in boys, and add to the growing evidence that exposure to organochlorine pesticides early in life impairs child development.
ISSN: 0161-813X

hal-00875907
https://hal.archives-ouvertes.fr/hal-00875907
PUBMED : 23376090
DOI : 10.1016/j.neuro.2013.01.007

Éditeur(s) : HAL CCSD Springer International Publishing
Résumé : The intensive farming practices that have been developed over the past 60 years are based mainly on the use of chemical inputs such as fertilisers and pesticides, mechanical tillage and monoculture. The limitations of these methods are now clear: long-term degradation of soil fertility, impacts on the environment and human health, high consumption of fossil fuels, low efficiency of inputs and threats to food security in a context of climate change. Would farming practices that rely on the activation of ecological processes be an alternative to achieve a balance between high productivity and environmental preservation? While many studies suggest a positive relationship between soil biodiversity and ecosystem services, there is considerable debate on the form such agricultural systems should take. This study reviewed the state of current knowledge and identified aspects requiring further research to achieve the aim of sustainable intensification of agriculture. The following major points emerged: 1) Most studies focused on the evaluation of individual practices. However, changes in farmers’ cropping practices to take advantage of soil biodiversity services would need to manage not only the interactions between various practices but also the trade-off between the technical and socio economic constraints of cropping systems. Advances in agricultural system design approaches may help to ensure appropriate trade-offs. 2) More attention should be given to drawing on knowledge from different sources: laboratory studies focusing on the ecological functions of soil biodiversity, experimental surveys on farmers’ fields to rank the farming practices and processes to be included in site-specific models, and on- station experiments to test hypotheses and acquire additional reference material. 3) Whereas advances in technical and scientific knowledge provide an increasing number of relevant indicators for characterizing biodiversity and ecological functions, studies are rarely targeted at the development of indicators that are accessible to farmers or their technical advisors. The lack of indicators accessible to grassroots players for evaluating the impacts of their decisions on soil biodiversity remains a serious obstacle to the development of innovative agro-ecological systems.
Sustainable Agriculture Reviews 14

ISBN : 978-3-319-06015-6
hal-01268743
https://hal.archives-ouvertes.fr/hal-01268743
DOI : 10.1007/978-3-319-06016-3_5
PRODINRA : 270786

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Aim The aim of the present study was to examine whether listening to music during warming-up might influence short-term maximal performance (STMP), cognitive anxiety, self-confidence, and enjoyment during Ramadan, and whether these affects might predict STMP. Methods Nine male physical education students (age: 21 ± 1.1 years; height: 1.8 ± 0.04 m; body mass: 83 ± 5 kg) volunteered to participate in the present study. A within-subjects design consisted of four experimental sessions: Two sessions occurred one week before Ramadan and two others took place during Ramadan. They were scheduled at 5 p.m. and were conducted as follows: After a 10-minute warm-up either with or without listening to music, each participant performed a 5-m multiple shuttle run test, after which he was asked to answer items intended to assess his affective state during the experimental task. Results Our findings revealed that STMP was lower during Ramadan than before Ramadan in the no-music condition. Additionally, it was found that STMP was higher in the music condition than in the no-music condition during Ramadan, and that STMP measured before Ramadan did not differ from that measured during Ramadan in the music condition. Regarding affects, the findings revealed that enjoyment was lower during Ramadan than before Ramadan in the music condition, and that cognitive anxiety was lower in the music condition than in the no-music condition before Ramadan. Self-confidence was not influenced by the experimental conditions. Conclusion This study showed that listening to music during warming-up not only would be beneficial for STMP in Ramadan fasters, but also would counteract the negative effects of Ramadan observance on STMP.
ISSN: 1932-6203

hal-01467699
https://hal-univ-paris10.archives-ouvertes.fr/hal-01467699
DOI : 10.1371/journal.pone.0136400

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We developed a new granular material (MatIV) to study experimentally landscape evolution in active mountain belt piedmonts. Its composition and related physical properties have been determined using empirical criteria derived from the scaling of deformation, erosion-transport and sedimentation natural processes. MatIV is a water-saturated composite material made up with 4 granular components (silica powder, glass microbeads, plastic powder and graphite) whose physical, mechanical and erosion-related properties were measured with different laboratory tests. Mechanical measurements were made on a modified Hubbert-type direct shear apparatus. Erosion-related properties were determined using an experimental set-up that allows quantifying the erosion/sedimentation budget from tilted relaxation topographies. For MatIV, we also investigated the evolution of mean erosion rates and stream power erosion law exponents in 1D as a function of slope.;Our results indicate that MatIV satisfies most of the defined criteria. It deforms brittlely according to the linear Mohr-Coulomb failure criterion and localizes deformation along discrete faults. Its erosion pattern is characterized by realistic hillslope and channelized processes (slope diffusion, mass wasting, channel incision). During transport, eroded particles are sorted depending on their density and shape, which results in stratified alluvial deposits displaying lateral fades variations. To evaluate the degree of similitude between model and nature, we used a new experimental device that combines accretionary wedge deformation mechanisms and surface runoff erosion processes. Results indicate that MatIV succeeded in producing detailed morphological and sedi-mentological features (drainage basin, channel network, terrace, syntectonic alluvial fan). Geometric, kinematic and dynamic similarity criteria have been investigated to compare precisely model to nature. Although scaling is incomplete, it yields particularly informative orders of magnitude. With all these characteristics, MatIV appears as a very promising material to investigate experimentally a wide range of scientific questions dealing with relief dynamics and interactions between tectonics, erosion and sedimentation processes.
ISSN: 0040-1951

hal-00669904
https://hal.archives-ouvertes.fr/hal-00669904
DOI : 10.1016/j.tecto.2011.09.029

Éditeur(s) : Wiley-blackwell Publishing, Inc
Résumé : Vibrio splendidus, strain LGP32, is an oyster pathogen associated with the summer mortalities affecting the production of Crassostrea gigas oysters worldwide. Vibrio splendidus LGP32 was shown to resist to up to 10 mu M Cg-Def defensin and Cg-BPI bactericidal permeability increasing protein, two antimicrobial peptides/proteins (AMPs) involved in C. gigas immunity. The resistance to both oyster Cg-Def and Cg-BPI and standard AMPs (polymyxin B, protegrin, human BPI) was dependent on the ompU gene. Indeed, upon ompU inactivation, minimal bactericidal concentrations decreased by up to fourfold. AMP resistance was restored upon ectopic expression of ompU. The susceptibility of bacterial membranes to AMP-induced damages was independent of the ompU-mediated AMP resistance. Besides its role in AMP resistance, ompU proved to be essential for the adherence of V. splendidus LGP32 to fibronectin. Interestingly, in vivo, ompU was identified as a major determinant of V. spiendidus pathogenicity in oyster experimental infections. Indeed, the V. splendidus-induced oyster mortalities dropped from 56% to 11% upon ompU mutation (Kaplan Meier survival curves, P < 0.01). Moreover, in co-infection assays, the ompU mutant was out competed by the wild-type strain with competitive indexes in the range of 0.1-0.2. From this study, ompU is required for virulence of V. splendidus. Contributing to AMP resistance, conferring adhesive properties to V. splendidus, and being essential for in vivo fitness, the OmpU porin appears as an essential effector of the C. gigas/V. splendidus interaction.
Environmental Microbiology (1462-2912) (Wiley-blackwell Publishing, Inc), 2010-04 , Vol. 12 , N. 4 , P. 951-963

Droits : 2010 Society for Applied Microbiology and Blackwell Publishing Ltd
http://archimer.ifremer.fr/doc/00003/11421/8044.pdf
DOI:10.1111/j.1462-2920.2009.02138.x
http://archimer.ifremer.fr/doc/00003/11421/