Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Underground CO2 sequestration is highly recommended as an effective means of significantly decreasing CO2 concentration in the atmosphere. Mineral storage is the more secure technology, but requires the presence of high concentration of divalent cations in the pore-fluid. Results from CO2 percolation experiments through chlorite/zeolite-rich sandstone samples from the Pretty Hill Formation (Otway Basin, Australia) are presented. The dissolution of the laumontite (7 wt.%) and chamosite (7 wt.%) are the potential sources of calcium, iron and magnesium required for carbonate precipitation. The percolation experiment was setup to reproduce, at laboratory scale, the in situ temperature and pressure conditions (T = 95 degrees C and P = 10 MPa). The fluid injected at constant flow rate is a rock-equilibrated brine subsequently enriched in CO2 up to partial pressure of 6 MPa. We observe feldspars, laumontite and chamosite dissolution, kaolinite and silica precipitation and a noticeable sink of CO2 in the sample which is attributed to the precipitation of both amorphous carbon due to the reduction of CO2 and Fe-rich carbonate. Permeability decreases of about one order of magnitude due to the localization of the kaolinite precipitation in the main flow paths, while porosity increases. The high reactivity of this sandstone makes this reservoir a valuable target for CO2 mineralization, but the associated permeability decrease may limit the injection rate and the spreading of the CO2 in the reservoir.
ISSN: 0009-2541

hal-00712829
https://hal.archives-ouvertes.fr/hal-00712829
DOI : 10.1016/j.chemgeo.2011.11.018

Éditeur(s) : Elsevier Science Bv
Résumé : Monitoring fish and underwater habitats, particularly in and around marine protected areas (MPAs) requires non-destructive observation methods. This is generally achieved by divers conducting underwater visual censuses (UVC), but video-based techniques are now being used more often to observe underwater macrofauna and habitats. A comparison of these two techniques is relevant with the development of high-definition (HD) video, which constitutes a substantial improvement over previously available video resolutions at limited extra cost. We conducted a paired observation experiment involving both HD video and UVC in an MPA located in the New Caledonian lagoon, which is a highly diversified coral reef ecosystem. We compared three techniques for counting fish along 50 m x 4 m delineated strip transects: UVC and two video techniques in which the diver used either a straight trajectory (I-type transect) or a browsing one (S-type transect). The results showed that the proportion of fish that were not identified up to the species level did not exceed 3.3% in video observations versus 1.7% in UVC. The abundance and species richness were larger in UVC than in videos, and S-type transects detected more individuals and species than I-type transects. The average abundance and species richness observed by UVC were 1094 individuals and 69.7 species per transect respectively. In comparison with UVC. I-type and S-type video transects detected on average 56% and 61% of the abundance and 85% and 77% of the species richness seen by UVC respectively. Our results showed that, in comparison to UVC data recorded in situ, the post field analysis of HD video images provided representative observations of fish abundance and species diversity, although fewer species and individuals were detected. The advantages and shortcomings of each observation technique for monitoring fish assemblages, particularly in an MPA are discussed. HD video appears to be a cost-effective technique in terms of the human resources and time needed for field implementation. Overall, this study suggests that HD video-based techniques constitute an interesting complement to UVC, or an alternative when these cannot be implemented. (C) 2010 Elsevier B.V. All rights reserved.
Fisheries Research (0165-7836) (Elsevier Science Bv), 2011-01 , Vol. 107 , N. 1-3 , P. 84-93

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00031/14192/11470.pdf
DOI:10.1016/j.fishres.2010.10.011
http://archimer.ifremer.fr/doc/00031/14192/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
1. The use of targets to provide measurable objectives and benchmarks for management, conservation, andrestoration of ecosystems is commonplace. In the marine and coastal realms, targets have been successful insetting sustainable limits to fisheries harvests, thresholds for pollutants, and recommended amounts ofrepresentative habitat included in marine protected area (MPA) networks. Quantifiable targets can dissuadegovernments from making dubious claims about investments in ocean protection that sound impressive butcannot be verified. Examples are presented where protection targets have been used successfully for marinemanagement, and instances where measurable and meaningful benchmarks serve to allow tracking of true progress.2. However, the setting of targets can also be a double-edged sword. In some cases, targets have proven useful,but in many instances, interventions made to fulfil targets not only give a false illusion of progress or even success,they present opportunity costs that impede further conservation.3. Some of these issues were raised in the 2003 article ‘Dangerous Targets?: Unresolved issues and ideologicalclashes around marine protected areas’ that appeared in Aquatic Conservation: Marine and FreshwaterEcosystems. Since its publication, the article’s warnings about how targets can sometimes be dangerous andcounter-productive have led to intense debate among scientists and policy-makers alike, and the paper has beencited in more than 500 publications. Yet today, more than a dozen years after the first ‘Dangerous Targets’publication, new targets are driving more MPA designations and conservation strategies than ever before, andthe ‘dangerous’ aspects of target setting have been largely ignored.4. This paper discusses old ‘dangers’ in the context of new developments in marine conservation, including thelingering problem of having simplistic metrics drive marine policies, and the unintended result that can often occurwhen outputs (percentage of area under MPA designation) do not align with true outcomes of effectivemanagement and conservation. Newly emerging ‘dangers’ in letting areal targets (percentage of area underMPA designation) drive MPA designations are also discussed, including how the rush to fulfil obligations toprotect a certain proportion of area is taking place in planning, separate from broader level, and potentiallymore holistic, marine spatial planning (MSP).5. The paper suggests five recommendations that would allow policy-makers to use targets more effectively,including: (1) increase transparency in planning, especially around specific goals and objectives of MPAestablishment; (2) use time-based areal targets when representativity is a goal of the protected area strategy; (3)
ISSN: 1052-7613

hal-01380963
https://hal-univ-perp.archives-ouvertes.fr/hal-01380963
DOI : 10.1002/aqc.2675

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 Elsevier
Résumé : International audience
A reactive percolation experiment was conducted by injecting seawater into a permeable olivine aggregate at 190 °C and 19 MPa to explore the relationships between hydration reactions and hydrodynamic properties during the onset of serpentinization in the ultramafic lithosphere exposed at mid-ocean ridges. The experiment was stopped after 23 days when the sample became impermeable. The initial flow rate was 0.2 mL/h and then was decreased down to 0.06 mL/h after 8 days. Permeability decreased continuously throughout the experiment. The analyses of fluid chemistry time series and of the mineralogy and structure of the reacted sample showed olivine dissolution and precipitation of proto-serpentine, brucite and Fe-oxides. These reactions are controlled by coupled hydrodynamic and chemical processes interacting at different time and spatial scales. Their first characteristic is the production of silica rich outlet fluids in disequilibrium with the observed reacted mineral assemblages. These compositions are interpreted as resulting from a suite of coupled dissolution-precipitation reactions, controlled at the pore scale by surface kinetic processes, that rapidly reaches steady-state (constant fluid composition independent of fluid flux). Hence, the effective rate of serpentinization was controlled, to the first order, by the transport of reactants during the experiment. Mass balance calculations show that the rate of olivine conversion was fast (0.2-0.5 wt%/day), yet only ∼8 wt% of the olivine sample reacted, because the permeability drop limited fluid circulation. Porosity varied little during the experiment compared to permeability changes: the decrease of permeability was explained by the structure of the newly formed serpentine favouring the clogging of fluid paths. The rate at which permeability decreased was the fastest at low flux conditions. This suggests that permeability changes were not controlled simply by the kinetics of the serpentinization reactions, but mainly reflected the development of low Peclet pore scale zones forming micro-environments that control the serpentinization reaction-paths. These results outline the need to take into account the coupling of hydrodynamic and chemical processes when modelling the effects of reactive transport within the hydrating oceanic lithosphere.
ISSN: 0012-821X

hal-00855043
https://hal.archives-ouvertes.fr/hal-00855043
DOI : 10.1016/j.epsl.2013.03.052

Résumé : The main aim of the CAMP project (2009-2011) is to estimate the efficient connectivity between the Marine Protected Areas (MPA) of the South-West Indian Ocean (SWIO). For that purpose, we use a population genetics approach on 3 reef fishes: Epinephelus merra, Lutjanus kasmira et Myripristis berndti. The overall goal of the project is to provide new elements to MPA managers that will contribute to design the best network of MPAs in the SWIO. In the first year of the project, most of the time was spent to sample fishes. Based on collaborations with 5 international and national partners, we succeed to sample more than 1100 fishes within 12 sites of the SWIO. More than 850 of the 1100 fishes were already sequenced. The development of third microsatellite libraries is under-going and should be available for the 2nd part of the year 2010. The second year of the project (2010) will focus on the end of the sampling in the SWIO as well as doing most of the genetic analysis of the samples collected in 2009 (microsatellit analysis) and in 2010 (mtDNA sequencing). At the end of the second year, we expect to be able to do a first regional analysis of the genetic structure of these reef fishes population. Then, in 2011, the project team will elaborate some recommendations to MPAs managers on the basis of the whole genetic dataset
L’objectif principal du projet CAMP (2009-2011) est d’estimer la connectivité effective entre les Aires Marines Protégées (AMP) du sud ouest de l’océan Indien (SOOI) par le biais de la génétique des populations de 3 modèles biologiques : Epinephelus merra, Lutjanus kasmira et Myripristis berndti. L’objectif final est de fournir des éléments de réflexion aux gestionnaires afin de contribuer significativement au dessin du réseau des AMPs dans le SOOI. La première année du projet a été consacrée essentiellement à l’échantillonnage. Basé sur une coopération avec nos 5 partenaires nationaux et internationaux, cet échantillonnage a permis de collecter plus de 1100 échantillons de tissus de ces 3 espèces de poissons répartis dans 12 sites du SOOI. Sur ces 1100 poissons, plus de 850 séquences d’ADN mitochondrial ont d’ores et déjà été effectuées. En parallèle, le développement des banques microsatellites pour les 3 espèces est en cours et devrait être disponible pour à la mi 2010. La deuxième année du projet (2010) aura pour objectif de poursuivre l’échantillonnage sur l’ensemble du SOOI et de réaliser les analyses microsatellites des échantillons collectés en 2009 ainsi que les séquences des échantillons collectés en 2010. Au terme de cette deuxième année, une analyse de la structure génétique de ces populations de poissons de récifs pourra être menée, suivie en 2011 de l’élaboration d’aides à la gestion sur la base de l’ensemble des données acquises dans le cadre de ce projet.

Droits : 2010 Ifremer
http://archimer.ifremer.fr/doc/00100/21086/18710.pdf
http://archimer.ifremer.fr/doc/00100/21086/

Éditeur(s) : HAL CCSD
Résumé : Scope: TNF-Related Apoptosis-Inducing Ligand (TRAIL) induces apoptosis via the extrinsic death pathway in human colon cancer cells. Short Chain Fatty Acids (SCFA) by contrast induce apoptosis of cancer cells via the intrinsic death pathway. We have previously shown that food-grade dairy propionibacteria induce intrinsic apoptosis of colon cancer cells, via SCFA metabolites (propionate and acetate) acting on mitochondria. We investigate here the possible synergistic pro-apoptotic effect between Propionibacterium freudenreichii and TRAIL. Methods and results: Whole transcriptomic analysis demonstrated that propionibacterial supernatant or propionibacterial SCFA, in combination with TRAIL, increased pro-apoptotic gene expression (TRAIL-R2/DR5) and decreased anti-apoptotic gene expression (FLIPL, XIAP) in HT29 human colon cancer cells. The revealed synergistic pro-apoptotic effect, depending on both death receptors (TRAIL-R1/DR4, TRAIL-R2/DR5) and caspases (caspase-8, -9 and -3) activation, was lethal on cancer cells but not on normal human intestinal epithelial cells (HIEC), and was inhibited by Bcl-2 expression. Finally, milk fermented by P. freudenreichii induced HT29 cells apoptosis and enhanced TRAIL cytotoxic activity, as did P. freudenreichii culture supernatants or its SCFA metabolites.Conclusion: The revealed synergy opens new applications for food-grade P. freudenreichii-containing products as new adjuvants to potentiate TRAIL-based cancer therapy in colorectal cancer.
International Scientific Conference on Probiotics and Prebiotics - IPC2016
Budapest, Hungary

hal-01286497
https://hal.archives-ouvertes.fr/hal-01286497
PRODINRA : 349367

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
A series of two-stage torsion experiments on Carrara marble were conducted to constrain the influence of known prior deformation on rheological response and microstructural evolution. Comparison with previous experimental data on Carrara marble flow and fabric evolution during single-stage torsion deformation experiments provided direct insights into the significance of initial deformation at various conditions. Our experiments were conducted at 727 degrees C temperature and 300 MPa confining pressure, while maintaining a constant strain rate of 3 x 10(-4) s(-1) on the periphery of the cylindrical samples. Under these conditions, the marble is known to deform in power-law (n = 6-10) ductile flow. All torsion experiments were performed with a Paterson type gas-medium testing machine equipped with a torsion actuator module.;Prior (D1) and subsequent (D2) deformation are accomplished by two torsion experiments in sequence on same sample segments. The effect of D1 strain history is investigated during D2 by applying counter-clockwise torsion to a sandwich sample consisting of three segments with different D1 rotation sense. D2 samples experienced continued, first and reversed shearing deformation in top, centre and bottom segments, respectively. D2 bulk strain was chosen equal to D1 strain in top and bottom segments.;D1 experiments followed the typical single-stage deformation behaviour of Carrara marble under the applied experimental conditions. Yielding was followed by strain hardening until a peak stress was reached at a shear strain around 1, after which work softening occurred. Weakening gradually evolved into a constant stress regime. During hardening, a shear microstructure and crystallographic preferred orientation (CPO) developed. Afterwards the volume fraction of smaller dynamic recrystallised grains increased continuously, resulting in a recrystallisation microstructure and CPO at shear strains of 5 and higher. The new D2 experiments displayed a strain variation between homogeneously deformed sample segments that increased with increasing D1 strain. The stress-strain behaviour of the D2 bulk sandwich samples showed less pronounced work-hardening and -softening when compared with single-stage deformation experiments. Furthermore, constant flow stress was attained at increasingly lower strain with increasing D1 strain. In most D2 segments, fabric development is equivalent to single-stage experiments at corresponding absolute strain. The fabrics differed markedly from those in single-stage experiments in the case of reversed two-stage deformation at moderate strain (D1 shear strain 1 and 2.6). Experiments show that grain shape by shearing of relict grains is defined by finite strain and thus affected by strain reversal. Recrystallisation is controlled by absolute strain and not influenced by strain reversal.
ISSN: 0040-1951

hal-00617686
https://hal.archives-ouvertes.fr/hal-00617686
DOI : 10.1016/j.tecto.2010.09.029

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) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The mantle above a subducting slab is the site of complex interactions between deformation, partial melting, fluid migration and magma transport. To constrain these interactions and their effects on olivine deformation, we analyze microstructures, crystal preferred orientations, and water contents of peridotite xenoliths entrained by andesites of the Avacha volcano, southern Kamchatka arc. These xenoliths are refractory spinel harzburgites that have coarse-grained microstructures with widely spaced subgrain boundaries and sinuous grain boundaries in olivine, consistent with deformation by dislocation creep under low deviatoric stress (< 13 MPa) and with a significant contribution from diffusional processes. Analysis of crystal preferred orientations (CPO) indicates dominant activation of high-temperature, low-stress {0kl}[100] slip systems in olivine and of(100)[001] in orthopyroxene. In most samples, coarse opx crystals, elongated parallel to the lineation, enclose small olivine grains in crystallographic continuity with neighbouring crystals, indicating crystallization of orthopyroxene at the expense of olivine as a result of reactive percolation of Si-rich fluids coeval with the high-temperature deformation. Secondary crystallization of interstitial orthopyroxene led locally to development of opx-rich lenses parallel to the foliation, characterized by a decrease in olivine grain size and dispersion of the olivine CPO without changing the dominant slip systems. Half of the samples also show acicular orthopyroxene aggregates with which is associated a fine-grained matrix composed of rounded strain-free olivine, orthopyroxene, spinel, and rare amphibole crystals. This matrix occurs pervasively along grain boundaries or forms millimeter-scale irregular lenses and anastomosing veinlets that crosscut the coarse crystals and their ductile deformation structures. Both acicular orthopyroxene and the fine-grained matrix are interpreted as resulting from reactive transport of H2O-rich fluids under static conditions, probably in the lithospheric mantle. Infrared analyses show that olivine contains 1-8 center dot 6 ppm by weight of water. These low water contents are similar to those observed in spinel peridotites from other subduction zones and probably record both the low solubility of water in olivine at low pressure and dehydration during exhumation of the xenoliths. Water contents in orthopyroxene are highly variable (25-506 ppm H2O), probably recording spatially heterogeneous interaction with fluids or melts and compositional disequilibrium in the studied samples. Change in the dominant percolation mechanism from porous flow to fracturing suggests cooling, consistent with the low temperatures estimated from pyroxene thermometry (< 800-900 degrees C). The Avacha xenoliths therefore record pervasive deformation of a region of the mantle under asthenospheric conditions, followed by its accretion to the base of the lithosphere, probably as a result of cooling of the mantle wedge. Percolation of Si-rich fluids or hydrous melts is recorded at all stages; this probably enhanced diffusion and lowered deviatoric stresses during ductile deformation, but did not change the dominant slip direction in olivine from [100] to [001].
ISSN: 0022-3530

hal-00456053
https://hal.archives-ouvertes.fr/hal-00456053
DOI : 10.1093/petrology/egp085

Éditeur(s) : HAL CCSD Taylor & Francis (Routledge): STM, Behavioural Science and Public Health Titles
Résumé : International audience
The aim of this study was to determine factors associated with complete satisfaction with the care provided (satisfaction with physicians and satisfaction with services and organization) among HIV-infected patients followed up in the French ANRS CO8 APROCO-COPILOTE cohort. Analyses focused on cross-sectional data collected during the ninth year of cohort follow-up. Satisfaction with care, sociodemographic characteristics, and behavioral data were collected using self-administered questionnaires, while clinical data were derived from medical records. Complete satisfaction with care was defined as being 100% satisfied. Two logistic regression models were used to identify predictors of (1) complete satisfaction with physicians (n=404) and (2) complete satisfaction with services and organization (n=396). Sixteen percent of patients were completely satisfied with physicians, while 15.9% were completely satisfied with services and organization. Being older and reporting fewer discomforting antiretroviral therapy (ART) side effects were factors independently associated with complete satisfaction with both physicians and services and organization. Strong support from friends and absence of hepatitis C (HCV) co-infection were independently associated with complete satisfaction with physicians, while strong support from one's family and comfortable housing conditions were independently associated with complete satisfaction with services and organization. Even after nine years of follow-up, social vulnerabilities still strongly influence HIV-infected patients' interactions with the health care system. Day-to-day experience with the disease, including perceived treatment side effects, appears to play a key role in the quality of these interactions. More attention should be given to patient satisfaction, especially for socially vulnerable patients, in order to avoid potentially detrimental consequences such as poor adherence to ART.
AIDS Care

hal-00875619
https://hal.archives-ouvertes.fr/hal-00875619
DOI : 10.1080/09540121.2011.613909
PUBMED : 21999644

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We conducted triaxial compression experiments to investigate the effects of pressure, temperature and strain rate on the rheology of talc rocks. The tests were carried out at T from 25 to 860 degrees C, P from 0.1 to 300 MPa, and <(epsilon) over dot> from 0.3 to 30 x 10-5 s(-1). In addition to being very weak, there are other important differences between the mechanical behavior of talc and that of most other silicates. Deformation at all temperatures up to dehydration was accommodated by a combination of crystal plasticity, frictional sliding, and cataclasis. A transition from localized to distributed deformation occurred at P = 300 MPa and T = 400 degrees C, but this transition is ill-defined as both distributed and localized deformation were observed at P = 300 MPa and T = 600 degrees C. Unlike most silicates, both the coefficient of internal friction and the coefficient of (sliding) friction are very low and nearly equal to each other. Temperature enhances plastic deformation (kinking), and inter- and intra-granular microcracks are observed parallel to the (001) planes at all conditions. Voids are created by delamination along (001) planes at kink-band boundaries. Full crystal plasticity was not achieved under any of the conditions tested, i.e., the von Mises criterion was never satisfied. However, the strength of the aggregates remained much less than the confining pressure. These unusual properties are likely a manifestation of the pronounced mechanical anisotropy of talc at the grain scale. At T >= 750 degrees C dehydration is observed, but only along shear zones. These results suggest that feedbacks between deformation and reaction kinetics could control fluid flow in fault zones. The presence of talc can promote significant weakening and strain localization in the oceanic lithosphere, the subducting plate and the overlying mantle wedge. (c) 2008 Elsevier B.V. All rights reserved.
ISSN: 0012-821X

hal-00492706
https://hal.archives-ouvertes.fr/hal-00492706
DOI : 10.1016/j.epsl.2008.02.004

Éditeur(s) : HAL CCSD Inter-Research
Résumé : International audience
Ecological connectivity is important for effective marine planning and biodiversity conservation. Our aim was to identify factors important in influencing variation in benthic community structure on shallow rocky reefs in 2 regions of the Mediterranean Sea with contrasting oceanographic regimes. We assessed beta (β) diversity at 146 sites in the littoral and shallow sub-littoral from the Adriatic/Ionian Seas (eastern region) and Ligurian/Tyrrhenian Seas (western region) using a null modelling approach to account for variation in species richness. The distance decay relationship between species turnover within each region and geographic distance by sea was determined using generalised linear models. Mantel tests were used to examine correlations between β diversity and connectivity by ocean currents, estimated from Lagrangian dispersal simulations. Variation in β diversity between sites was partitioned according to environmental and spatial components using a distance-based redundancy approach. Species turnover along a gradient of geographic distance was greater by a factor of 3 to 5 in the western region than the eastern region, suggesting lower con-nectivity between sites. β diversity was correlated with connectivity by ocean currents at both depths in the eastern region but not in the western region. The influence of spatial and environmental predictors of β diversity varied considerably between regions, but was similar between depths. Our results highlight the interaction of oceanographic, spatial and environmental processes influencing benthic marine β diversity. Persistent currents in the eastern region may be responsible for lower observed β diversity compared to the western region, where patterns of water circulation are more variable.
Marine Ecology Progress Series

Droits : http://creativecommons.org/licenses/by/
hal-01357935
https://hal-univ-perp.archives-ouvertes.fr/hal-01357935
https://hal-univ-perp.archives-ouvertes.fr/hal-01357935/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01357935/file/m553p001.pdf
DOI : 10.3354/meps11783

Éditeur(s) : Inter-research
Résumé : Marine protected areas (MPAs) have the potential to enhance the long-term sustainability of coastal resources, and the artisanal fisheries which depend on them. However, recreational fisheries, which are increasing their impacts on coastal resources worldwide, may reduce the benefits that MPAs provide to declining artisanal fisheries. Here we used the Bonifacio Straits Natural Reserve (BSNR) Corsica as a study case to simulate the combined effects on coastal resources of artisanal and recreational fishing efforts. The BSNR ecosystem was modelled using mass-balance modelling of trophic interactions. This model was compared to another built on a non-protected area from the same region. We aggregated fishing fleets into artisanal and recreational categories, and we simulated various combinations of fishing effort over a 20 yr dynamic simulation using Ecosim. We showed that fishing activities have an additional top-down effect on the food web and that they decrease the targeted group's biomass, such as piscivorous species. We found, for some trophic groups, non-trivial patterns of biomass variation through trophic cascades. Our trophic approach revealed that some groups may suffer a biomass decrease when MPAs are set or enforced, due to the combined effect of artisanal and recreational fisheries. Overall, our results illustrate the value of modelling to manage MPAs, as a complementary tool to surveys. Models provide the opportunity to anticipate the potential consequences, at the ecosystem level, of socio-political decisions that aim to sustain coastal resources while managing artisanal and recreational fisheries.
Marine Ecology-progress Series (0171-8630) (Inter-research), 2010-08 , Vol. 412 , P. 207-221

Droits : Inter-Research 2010
http://archimer.ifremer.fr/doc/00013/12436/9246.pdf
http://archimer.ifremer.fr/doc/00013/12436/9247.pdf
DOI:10.3354/meps08679
http://archimer.ifremer.fr/doc/00013/12436/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: Evidence of human sexual transmission during Zika virus emergence is a matter of concern, particularly in procreation, but to date, kinetics of seminal shedding and the effects of infection on human reproductive function have not been described. To investigate the effects of Zika virus infection on semen and clearance of Zika virus from semen and body fluids, we aimed to study a cohort of Zika virus-infected men. METHODS: This prospective observational study recruited men presenting with acute Zika virus infection at Pointe-à-Pitre University Hospital in Guadeloupe, French Caribbean, where a Zika virus outbreak occurred between April and November, 2016. Blood, urine, and semen were collected at days 7, 11, 20, 30, 60, 90, and 120 after symptom onset, and semen characteristics, such as total sperm count, sperm motility, vitality, and morphology, and reproductive hormone concentrations, such as testosterone, inhibin, follicle-stimulating hormone, and luteinising hormone, were assessed. At days 7, 11, and 20, semen was processed to isolate motile spermatozoa. Zika virus RNA was detected by RT-PCR using whole blood, serum, urine, seminal plasma, semen cells, and motile spermatozoa fractions. Zika virus was isolated from different sperm fractions on Vero E6 cultures. FINDINGS: 15 male volunteers (mean age 35 years [SD 5; range 25-44) with acute Zika virus infection and positive Zika virus RNA detection in blood or urine were enrolled. Total sperm count was decreased from median 119 × 10(6) spermatozoa (IQR 22-234) at day 7 to 45·2 × 10(6) (16·5-89·6) at day 30 and 70 × 10(6) (28·5-81·4) at day 60, respectively, after Zika virus infection. Inhibin values increased from 93·5 pg/mL (IQR 55-162) at day 7 to 150 pg/mL (78-209) at day 120 when total sperm count recovered. In motile spermatozoa obtained after density gradient separation, Zika virus RNA was found in three of 14 patients at day 7, four of 15 at day 11, and four of 15 at day 20, and replication-competent virus was found in the tested patient. Seminal shedding kinetics seemed heterogeneous among patients. Whole blood was the fluid most frequently positive for Zika virus RNA (62 of 92 samples) and three patients remained positive at day 120. INTERPRETATION: Semen alterations early after acute Zika virus infection might affect fertility and could be explained by virus effects on the testis and epididymis. Frequency of shedding and high viral load in semen, together with the presence of replicative virus in a motile spermatozoa fraction, can lead to Zika virus transmission during sexual contact and assisted reproduction procedures. Whole blood seems to be the best specimen for Zika virus RNA detection, diagnosis, and follow-up. FUNDING: Agence de la Biomédecine/Agence Régionale de Santé de la Guadeloupe/Inserm-REACTing.
ISSN: 0140-6736

hal-01647078
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647078
DOI : 10.1016/S1473-3099(17)30444-9
PUBMED : 28838639

Éditeur(s) : HAL CCSD Elsevier
Résumé : Nominally anhydrous minerals (NAMs) of Earth's mantle can contain hydrogen as atomic impurity in their crystal structures. This hydrogen substantially modifies many physical properties of Earth's mantle rocks. Also, the Earth's deep interior is made of rocks where minerals are separated by nanometer-scale interfaces call grain boundaries and interphase boundaries. These grain boundaries should carefully be considered as a potential hydrogen reservoir as well. I report here an experimental investigation of hydrogen diffusion through grain boundaries in olivine polycrystalline aggregates. Hot-press and diffusion experiments were performed using a gas-medium high-pressure vessel at a confining pressure of 300 MPa, over a temperature range of 1000-1200 degrees C. The diffusion assembly consisted of a dense polycrystalline cylinder of natural olivine from San Carlos (Arizona) mixed with olivine singles crystals of millimeter size. This mixture was couple with a talc cylinder. Ni capsule were used to buffer the oxygen fugacity at Ni-NiO level. Experiment durations varied from 3 min to 4 h. The presence of hydrogen in the sample was quantified using Fourier transform infrared spectroscopy. The calculation of the diffusion coefficients was based on the estimation of the length of polycrystalline solid affected by the diffusion of hydrogen. The absence or presence of hydrogen was recorded by the large olivines behaving here as "hydrogen sensor", which are implanted in the aggregate. The results indicate that effective hydrogen diffusivity which includes grain boundaries effect in olivine aggregate is barely one order of magnitude faster than hydrogen diffusion in an olivine single crystal with a diffusivity similar to 8.5x 10(-10) m(2) s(-1) 1000 degrees C and only twice faster similar to 2.1 x10(-9) m(2) s(-1) 1200 degrees C. Calculations of the diffusion data in relation to the Arrhenius Law, yield an activation energy of similar to 70 +/- 10 kJ mol(-l) . From these effective diffusivities and combined with published diffusion data for olivine single crystals, hydrogen diffusion in grain boundaries is extracted and yield diffusivities almost three order of magnitude faster (similar to 5 x 10(-6) m(2) s(-1) at 1200 degrees C) than in an olivine single crystal at the equivalent high temperature. On geological scales and for coarse-grain rocks, hydrogen diffusivity in grain boundaries is not fast enough to compete with lattice diffusion. The relative large grain size of mantle rocks will ensure a very limited hydrogen transport by effective diffusion, and a good conservation of water-rich zones in the Earth's mantle.
ISSN: 0012-821X

hal-00512821
https://hal.archives-ouvertes.fr/hal-00512821
DOI : 10.1016/j.epsl.2010.04.019

Éditeur(s) : HAL CCSD
Résumé : Staphylococcus aureus can cause a wide range of infections in humans and warm-blooded animals. The epithelial surface is the principal site of staphylococcal infection. The goal of this work was to investigate the cytopathic effect of S. aureus and its ability to affect host cell cycle. Cultures of human cervix cancer HeLa and mammary gland bovine MAC-T epithelial cells were used to study in vitro the effects of S. aureus strains from human or ruminant origins. Using microscopic examination, we found that S. aureus induced an enlargement of the host cells and we observed that S. aureus slowed down cell proliferation. Similar effect was observed on both human and bovine cells using the human or the ruminant strains. Microscopic analysis of DAPI-stained cells revealed huge decrease of mitotic indexes in infected HeLa and Mac-T cells, synchronized by Double Thymidine Block. Flow cytometry analysis showed that S. aureus induces G2/M phase delay in synchronous HeLa cells. Western blot analysis revealed that the G2/M phase delay was associated with an accumulation of inactive phosphorylated cyclin-dependent kinase Cdk1/cdc2, a key inducer of mitosis entry, and dephosphorylation of core histone H3, an important component of the epigenetic landscape. Altogether, these results suggest that the delay in G2/M phase transition of the infected epithelial cells may be one of the mechanisms employed by S. aureus to survive and to propagate inside the host. Further investigations are ongoing to fully understand the mechanisms associated to this type of S. aureushost cell interactions.
journées des Microbiologistes de l' INRA 2012
L'Isle sur la Sorgue, France

hal-01209365
https://hal.archives-ouvertes.fr/hal-01209365
PRODINRA : 174569

Éditeur(s) : HAL CCSD
Résumé : Fault zones are major discontinuities in sedimentary basins. Understanding their role on fluid migrations is an essential issue to (i) characterize the mechanisms and kinematics of deformation and (ii) to determine the parameters which control the distribution of energetic or mineral resources. This work applies to faulting under a temperature range of 200-250°C, corresponding to that of deeply buried reservoirs as well as potentially seismogenic fault zones. The studied faults are normal faults affecting the “Grès d’Annot” Formation, a Priabonian-Rupelian siliclastic turbidite succession of the Alpine foreland basin. They are located in two distinct areas: the Moutière-Restefond area in the eastern part of the basin and the Estrop area in the western part. Vitrinite reflectance outside fault zones indicates maximal temperatures of 240-260°C at Moutière-Restefond and 170-200°C at Estrop, i.e. burial depths around 8 km and 6 km, respectively, assuming a mean geothermal gradient of 30°C/km. Burial was due to underthrusting below the Embrunais-Ubaye Alpine nappes, the difference in burial between the two areas traducing the westward taper of the nappe front.The studied faults affect alternating arkosic sandstone beds and pelite layers with offsets from centimeters to decameters. Two types of core zones are recognized: (1) the foliated core zones of the Moutière-Restefond area, where deformation dominated by pressure solution and synkinematic phyllosilicate neoformation resulted in a foliated fabric, and (2) the core zones of the Estrop area, characterized by dilatant quartz-mineralized veins and breccia. Fault and host rock petrophysical properties were measured on drill plugs, using the water porosity technique and nitrogen permeability technique under 2 Mpa of confining pressure. In the Moutière-Restefond fault zones, plug axes were oriented in three orthogonal directions corresponding to the main deformation axes (X, Y, Z) of the foliated arkose to characterize the effect of structural anisotropy. In the Estrop fault zones, where deformation does not show equivalent anisotropy, the plug axes were oriented according to the main fault plane orientation (i.e., parallel to azimuth, parallel to dip and normal). In each fault zone, the porosity of fault rocks is equivalent to that of host rocks. In the Moutière-Restefond fault zones, the plugs parallel to the X and Z axes of deformation have a permeability similar to that of the host rocks, whereas permeability parallel to the Y axis (i.e. parallel to the foliation and the main fault plane) is one order of magnitude higher. By contrast, the permeability values in the Estrop fault zones are isotropic and equivalent to the host rock values. This study highlights the importance of various types of deformation mechanisms and related fluid-rock interactions in determining different fault rock types within a similar protolith, ultimately controlling distinct petrophysical properties of fault zones.
Les zones de failles constituent des discontinuités majeures dans la croûte supérieure. Ce mémoire s’intéresse aux failles actives à des profondeurs de 5-8 km, i.e. dans des conditions pouvant jouer un rôle important (i) sur le comportement mécanique de de la croûte, en particulier sur son potentiel sismogénique et (ii) sur la compartimentation des réservoirs géologiques profondément enfouis.Les failles étudiées sont des failles normales (rejet jusqu’à 50 mètres) affectant des alternances de bancs de grès arkosiques et de pélites dans les Grès d’Annot, une formation turbiditique d’âge priabonien-rupélien du bassin d’avant-chaine alpin. Les Grès d’Annot ont été enfouis sous les nappes de l’Embrunais-Ubaye peu de temps après leur dépôt et exhumés au Miocène moyen-supérieur. L’étude a été réalisée dans deux secteurs des Alpes de Haute-Provence, (1) le secteur de l’Estrop (chaine des Trois Evéchés, dans la partie occidentale du bassin) et (2) le secteur de Point Vert-Restefond (alentours du col de la Bonette, dans la partie orientale du bassin). La réflectance de la vitrinite dans les Grès d’Annot indique des températures maximales de 160-190°C dans le secteur (1) et de 240-260 °C dans le secteur (2) , soit des profondeurs d’enfouissement de 5-6 km et 8-10 km, respectivement, dans l’hypothèse d’un gradient géothermique moyen de 25-30°C/km. A partir des observations microstructurales, de données d’inclusions de fluides, de modélisations thermodynamiques sur chlorites syncinématiques et des indices de cristallinité de l’illite, on a établi que les failles du secteur (1) ont fonctionné à une température d’environ 200°C pour une pression de 0.6Kbar et celles du secteur (2) dans une gamme de température de 200-220°C et de pression comprise entre 0.6 et 1.1 Kba. L’activité de la faille de Point-Vert a été datée par la méthode 40Ar/39Ar au Miocène inférieur (21 Ma). Ces failles sont interprétées comme associées aux premiers stades du soulèvement résultant de l’activité des chevauchements dans le socle sous-jacent.Deux types principaux de roches de failles caractérisent les failles étudiées. Les brèches dilatantes sont majoritaires dans les zones de failles du secteur (1) alors que les arkoses foliées sont majoritaires dans les zones de failles du secteur (2). Les brèches dilatantes témoignent de mécanismes de déformation dominés par la fracturation transgranulaire et la pression-solution des silicates. Ce dernier mécanisme se manifeste principalement par d’abondantes précipitations cycliques de quartz, les stylolites restant peu développés. Les géométries structurales sont associées à l’activation de plans T de Riedel déterminant l’ouverture de relais extensifs et un régime localement dilatant. Nous associons ce type de roche de faille à une faible pression effective au cours de la déformation.La déformation cisaillante exprimée dans les arkoses foliées témoigne de mécanismes de déformation dominés par (i) la fracturation intragranulaire et transgranulaire, (ii) la pressionsolution/ précipitation des silicates, principalement le quartz, (iii) la néoformation de micas blancs liée à l’altération des feldspaths et (iv) la précipitation de chlorite. Ce travail montre également que les transformations minéralogiques liées aux interactions fluide-roche dans la zone de faille (forte augmentation de la proportion des phyllosilicates au dépend des feldspaths) changent radicalementla composition minéralogique de la roche. Nous associons ce type de roche de faille à une forte pression effective au cours de la déformation.La pétrophysique montre que les brèches de failles (secteur 1) ont une perméabilité isotrope et équivalente à celle du protolithe (10-3mD sous 2 MPa de confinement) tandis que les roches foliées (secteur 2) montrent une augmentation de perméabilité (10-2mD) selon l’axe Y de la déformation, d’un ordre de grandeur supérieure aux perméabilités suivant les axes X et Z et dans la roche hôte (10-3mD). Ce drain préférentiel potentiel est associé à l’orientation des phyllosilicates dans la foliation.
https://hal.archives-ouvertes.fr/tel-01310382

tel-01310382
https://hal.archives-ouvertes.fr/tel-01310382
https://hal.archives-ouvertes.fr/tel-01310382/document
https://hal.archives-ouvertes.fr/tel-01310382/file/Th%C3%A8seCAVAILHES2012.pdf

Éditeur(s) : HAL CCSD
Résumé : Staphylococcus aureus can cause a wide range of infections in humans and warm-blooded animals. The epithelial surface is the principal site of staphylococcal infection. The goal of this work was to investigate the cytopathic effect of S. aureus and its ability to affect host cell cycle. Cultures of human cervix cancer HeLa and mammary gland bovine MAC-T epithelial cells were used to study in vitro the effects of S. aureus strains from human or ruminant origins. Using microscopic examination, we found that S. aureus induced an enlargement of the host cells and we observed that S. aureus slowed down cell proliferation. Similar effect was observed on both human and bovine cells using the human or the ruminant strains. Microscopic analysis of DAPI-stained cells revealed huge decrease of mitotic indexes in infected HeLa and Mac-T cells, synchronized by Double Thymidine Block. Flow cytometry analysis showed that S. aureus induces G2/M phase delay in synchronous HeLa cells. Western blot analysis revealed that the G2/M phase delay was associated with an accumulation of inactive phosphorylated cyclin-dependent kinase Cdk1/cdc2, a key inducer of mitosis entry, and dephosphorylation of core histone H3, an important component of the epigenetic landscape. Altogether, these results suggest that the delay in G2/M phase transition of the infected epithelial cells may be one of the mechanisms employed by S. aureus to survive and to propagate inside the host. Further investigations are ongoing to fully understand the mechanisms associated to this type of S. aureus-host cell interactions.
International Symposium on Staphylococci and Staphylococcal Infections -ISSSI-2012
Lyon, France

hal-01209356
https://hal.archives-ouvertes.fr/hal-01209356
PRODINRA : 173265

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
Abstract Indoor fungal contamination has been associated with a wide range of adverse health effects, including infectious diseases, toxic effects and allergies. The diversity of fungi contributes to the complex role that they play in indoor environments and human diseases. Molds have a major impact on public health, and can cause different consequences in hospitals, homes and workplaces. This review presents the methods used to assess fungal contamination in these various environments, and discusses advantages and disadvantages for each method in consideration with different health risks. Air, dust and surface sampling strategies are compared, as well as the limits of various methods are used to detect and quantify fungal particles and fungal compounds. In addition to conventional microscopic and culture approaches, more recent chemical, immunoassay and polymerase chain reaction (PCR)-based methods are described. This article also identifies common needs for future multidisciplinary research and development projects in this field, with specific interests on viable fungi and fungal fragment detections. The determination of fungal load and the detection of species in environmental samples greatly depend on the strategy of sampling and analysis. Quantitative PCR was found useful to identify associations between specific fungi and common diseases. The next-generation sequencing methods may afford new perspectives in this area.
ISSN: 1040-841X

hal-00874670
https://hal.archives-ouvertes.fr/hal-00874670
DOI : 10.3109/1040841X.2013.777687
PUBMED : 23586944