Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Cratons represent the oldest preserved lithospheric domains. Their lithosphere (lithospheric mantle welded to overlying Precambrian crystalline basement) is considered to be particularly robust and long-lived due to the protecting presence of buoyant and rigid “keels” made up of residual harzburgites. Although the cratons are mostly assumed to form in the Archaean, the timing of their formation remains poorly constrained. In particular, there are very few datasets describing concurrently the age of both the crustal and mantle portions of the lithosphere. In this study, we report new U–Pb ages and Hf isotope compositions for zircons in crustal xenoliths from the Udachnaya kimberlite in the central Siberian craton; this dataset includes samples from both the upper and lower portions of the crust. The zircon ages agree well with model melt-extraction Re–Os ages on refractory peridotite xenoliths from the same pipe; taken together they allow an integrated view of lithosphere formation. Our data reveal that the present day upper crust is Archaean, whereas both the lower crust and the lithospheric mantle yield Paleoproterozoic ages. We infer that the deep lithosphere beneath the Siberian craton was not formed in a single Archaean event, but grew in at least two distinct events, one in the late Archaean and the other in the Paleoproterozoic. Importantly, a complete or large-scale delamination and rejuvenation of the Archaean lower lithosphere (lower crust and lithospheric mantle) took place in the Paleoproterozoic. This further demonstrates that craton formation can be a protracted, multi-stage process, and that the present day crust and mantle may not represent complementary reservoirs formed through the same tectono-magmatic event. Further, deep cratonic lithosphere may be less robust and long living than often assumed, with rejuvenation and replacement events throughout its history.
ISSN: 0012-821X

hal-01467648
https://hal.archives-ouvertes.fr/hal-01467648
DOI : 10.1016/j.epsl.2016.09.046

Éditeur(s) : HAL CCSD
Résumé : International audience
This study investigated the possibility of there being differences in respiratory muscle strength and endurance in elite and competition triathletes who have similar maximal oxygen uptakes (V_O2max) and ventilatory thresholds (Thvent). Five internationally-ranked elite, [mean (SD) age 23.8 (1.4) years] and six nationallyand regionally-ranked competition [age 21.1 (1.1) years] male triathletes performed two successive trials: first an incremental cycle test to assess V_O2max and Thvent and second 20 min of cycling followed by 20 min of running (C-R) at intensities higher than 85% V_O2max. Cardioventilatory data were collected every minute during the two trials, using an automated breath-by-breath system. Maximal expiratory and inspiratory (PImax) strength were assessed before and 10 min after C-R from the functional residual capacity. Respiratory muscle endurance was assessed 1 day before and 30 min after C-R by measuring the time limit (tlim). The results showed firstly that during C-R, the competition triathletes had significantly (P<0.05) higher minute ventilation [mean (SEM) 107.4 (3.1) compared to 99.8 (3.7) lÆmin-1], breathing frequency [44.4 (2.0) compared to 40.2 (3.4) Æmin-1] and heart rate [166 (3) compared to 159 (4) beatsÆmin-1] and secondly that after C-R, they had significantly lower PImax [127.1 (4.2) compared to 130.7 (3.0) cmH2O] and tlim [2:35 (0:29) compared to 4:12 (0:20) min] than the elite triathletes. We conclude that, despite similar V_O2max and Thvent, the competition triathletes showed less extensive adaptive mechanisms, including those in the respiratory muscles, than did the elite triathletes. This led to higher ventilation, which appeared to be the cause of the faster development of fatigue in the inspiratory muscles in this group.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720562
https://hal.univ-antilles.fr/hal-00720562
https://hal.univ-antilles.fr/hal-00720562/document
https://hal.univ-antilles.fr/hal-00720562/file/BoussanaEJAP02_2_.pdf

Éditeur(s) : HAL CCSD American Chemical Society
Résumé : International audience
Aromatic amines and structurally related heterocyclic aromatic amines (HAAs) are produced during the combustion of tobacco or during the high-temperature cooking of meat. Exposure to some of these chemicals may contribute to the etiology of several common types of human cancers. 2-Amino-9H-pyrido[2,3-b]indole (AαC) is the most abundant HAA formed in mainstream tobacco smoke: it arises in amounts that are 25-100 times greater than the levels of the arylamine, 4-aminobiphenyl (4-ABP), a human carcinogen. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a prevalent HAA formed in cooked meats. AαC and MeIQx are rodent carcinogens; however, their carcinogenic potency in humans is unknown. A preliminary assessment of the carcinogenic potential of these HAAs in humans was conducted by examining the capacity of primary human hepatocytes to form DNA adducts of AαC and MeIQx, in comparison to 4-ABP, followed by the kinetics of DNA adduct removal by cellular enzyme repair systems. The principal DNA adducts formed were N-(deoxyguanosin-8-yl) (dG-C8) adducts. Comparable levels of DNA adducts were formed with AαC and 4-ABP, whereas adduct formation was ∼5-fold lower for MeIQx. dG-C8-AαC and dG-C8-4-ABP were formed at comparable levels in a concentration-dependent manner in human hepatocytes treated with procarcinogens over a 10,000-fold concentration range (1 nM-10 μM). Pretreatment of hepatocytes with furafylline, a selective inhibitor of cytochrome P450 1A2, resulted in a strong diminution of DNA adducts signifying that P450 1A2 is a major P450 isoform involved in bioactivation of these procarcinogens. The kinetics of adduct removal varied for each hepatocyte donor. Approximately half of the DNA adducts were removed within 24 h of treatment; however, the remaining lesions persisted over 5 days. The high levels of AαC present in tobacco smoke and its propensity to form persistent DNA adducts in human hepatocytes suggest that AαC can contribute to DNA damage and the risk of hepatocellular cancer in smokers.
ISSN: 0893-228X

inserm-00869907
http://www.hal.inserm.fr/inserm-00869907
DOI : 10.1021/tx4002226
PUBMED : 23898916

Éditeur(s) : Elsevier Sci Ltd
Résumé : Several marine geophysical data and piston-coring surveys acquired during the last decade allow one to better understand the close dynamic interactions between the sand-rich Orinoco turbidite system and the compressional structures of the Barbados prism. These interactions have been active since Eocene time as illustrated by the study of outcrops onshore Barbados Island. Because of strong morphologic and tectonic control in the east-Caribbean active margin, the present-day Orinoco turbiditic pattern system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the South-American margin induces the convergence of the turbidite channels toward the abyssal plain, at the front of the accretionary prism. Also, whereas in most passive margins the turbidite systems are organized upstream to downstream as canyon, channel-levee and lobes, here, due to the tectonic control, the sedimentary system is organized upstream to downstream as channel-levee, canyons and channelized lobes. Indeed, at the edge of the Orinoco platform, the system has multiple sources with several distributaries and downstream the channel courses are complex with frequent convergences or divergences that are emphasized by the effects of the undulating seafloor tectonic morphologies associated with active thrust tectonics and mud volcanism. On top of the accretionary prism, turbidite sediments are filling transported piggy-back basins whose timing of sedimentation vs. deformation is complex. While erosion processes are almost absent on the highly subsiding Orinoco platform and in the upper part of the turbidite system, they develop mostly between 2000 and 4000 m of water depth, above the compressional structures of the Barbados prism (canyons up to 3 km wide and 300 m deep). In the abyssal plain, the main turbiditic channel develops toward the east and connects with the Vidal mid-Atlantic channel. The sediments transported in this channel are filling several elongated basins linked with fracture zones (notably the Barracuda Basin), and finally end their course in the Puerto-Rico trench, the deepest morphologic depression of the region. Piston-cores have demonstrated that turbidite sediments above the accretionary prism and in the abyssal plain are mostly coarse sandy deposits covered by recent pelagic planktonic-rich sediments, which corresponds to slower sand deposition during the post-glacial sea level rise. Numerical stratigraphic modelling suggests that during the last glacial event, the main depocentres were located above the tectonic prism and in the abyssal plain, at the front of the prism and that, during the Holocene eustatic rise, a large accommodation space formed on the shelf confining sedimentation mostly on the Orinoco deltaic platform and producing a starvation downstream in the turbidite system.
Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2015-06 , Vol. 64 , P. 76-103

Droits : 2015 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00252/36373/34913.pdf
DOI:10.1016/j.marpetgeo.2014.12.015
http://archimer.ifremer.fr/doc/00252/36373/

Éditeur(s) : Ieee-inst Electrical Electronics Engineers Inc
Résumé : We validate Soil Moisture and Ocean Salinity (SMOS) sea surface salinity (SSS) retrieved during August 2010 from the European Space Agency SMOS processing. Biases appear close to land and ice and between ascending and descending orbits; they are linked to image reconstruction issues and instrument calibration and remain under study. We validate the SMOS SSS in conditions where these biases appear to be small. We compare SMOS and ARGO SSS over four regions far from land and ice using only ascending orbits. Four modelings of the impact of the wind on the sea surface emissivity have been tested. Results suggest that the L-band brightness temperature is not linearly related to the wind speed at high winds as expected in the presence of emissive foam, but that the foam effect is less than previously modeled. Given the large noise on individual SMOS measurements, a precision suitable for oceanographic studies can only be achieved after averaging SMOS SSS. Over selected regions and after mean bias removal, the precision on SSS retrieved from ascending orbits and averaged over 100 km $times$ 100 km and 10 days is between 0.3 and 0.5 pss far from land and sea ice borders. These results have been obtained with forward models not fitted to satellite L-band measurements, and image reconstruction and instrument calibration are expected to improve. Hence, we anticipate that deducing, from SMOS measurements, SSS maps at 200 km $times$ 200 km, 10 days resolution with an accuracy of 0.2 pss at a global scale is not out of reach.
Ieee Transactions On Geoscience And Remote Sensing (0196-2892) (Ieee-inst Electrical Electronics Engineers Inc), 2012-05 , Vol. 50 , N. 5 , P. 1662-1675

Droits : 2012 IEEE
http://archimer.ifremer.fr/doc/00074/18557/16108.pdf
DOI:10.1109/TGRS.2012.2184546
http://archimer.ifremer.fr/doc/00074/18557/

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : During the 2003 summer monsoon, the Hi-CLIMB seismological stations deployed across the Himalayan Range detected bursts of high-frequency seismic noise that lasted several hours to days. On the basis of the cross correlation of seismic envelopes recorded at 11 stations, we show that the largest transient event on 15 August was located nearby a village partially destroyed on that day by a devastating debris flow. This consistency in both space and time suggests that high-frequency seismic noise analysis can be used to monitor debris flow generation as well as the evacuation of the sediment. A systematic study of one year of seismic noise, focusing on the detection of similar events, provides information on the spatial and temporal occurrence of mass movements at the front of the Himalayas. With a 50% probability of occurrence of a daily event, a total of 46 debris flows are seismically detected. Most of them were generated in regions of steep slopes, large gullies, and loose soils during the 2003 summer monsoon storms. These events are compared to local meteorological data to determine rainfall thresholds for slope failures, including the cumulative rainfall needed to bring the soil moisture content to failure capacity. The inferred thresholds are consistent with previous estimates deduced from soil studies as well as sediment supply investigations in the area. These results point out the potential of using seismic noise as a dedicated tool for monitoring the spatiotemporal occurrence of landslides and debris flows on a regional scale.
ISSN: 0148-0227

hal-00464177
https://hal.archives-ouvertes.fr/hal-00464177
DOI : 10.1029/2008JF001198

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND: Histoplasmosis is an endemic fungal infection in French Guiana. It is the most common AIDS-defining illness and the leading cause of AIDS-related deaths. Diagnosis is difficult, but in the past 2 decades, it has improved in this French overseas territory which offers an interesting model of Amazonian pathogen ecology. The objectives of the present study were to describe the temporal trends of incidence and mortality indicators for HIV-associated histoplasmosis in French Guiana. METHODS: A retrospective study was conducted to describe early mortality rates observed in persons diagnosed with incident cases of HIV-associated Histoplasma capsulatum var. capsulatum histoplasmosis admitted in one of the three main hospitals in French Guiana between 1992 and 2011. Early mortality was defined by death occurring within 30 days after antifungal treatment initiation. Data were collected on standardized case report forms and analysed using standard statistical methods. RESULTS: There were 124 deaths (45.3%) and 46 early deaths (16.8%) among 274 patients. Three time periods of particular interest were identified: 1992-1997, 1998-2004 and 2005-2011. The two main temporal trends were: the proportion of early deaths among annual incident histoplasmosis cases significantly declined four fold (χ2, p<0.0001) and the number of annual incident histoplasmosis cases increased three fold between 1992-1997 and 1998-2004, and subsequently stabilized. CONCLUSION: From an occasional exotic diagnosis, AIDS-related histoplasmosis became the top AIDS-defining event in French Guiana. This was accompanied by a spectacular decrease of early mortality related to histoplasmosis, consistent with North American reference center mortality rates. The present example testifies that rapid progress could be at reach if awareness increases and leads to clinical and laboratory capacity building in order to diagnose and treat this curable disease.
ISSN: 1935-2727

inserm-01065109
http://www.hal.inserm.fr/inserm-01065109
http://www.hal.inserm.fr/inserm-01065109/document
http://www.hal.inserm.fr/inserm-01065109/file/PLOS_Neglected_Tropical_Dis_2014.pdf
http://www.hal.inserm.fr/inserm-01065109/file/2014_Adenis_-_HIV-associated_histoplasmosis_early_mor.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The development of inflammatory granulomas around infected Kupffer cells is necessary for hepatic parasite clearance during visceral leishmaniasis. Invariant NKT (iNKT) cells are predominant T cells in the mouse liver and can synthesize large quantities of IL-4 and IFN-γ, two cytokines involved in granuloma formation. This study analyzed the role of iNKT cells in the hepatic immune response during Leishmania donovani infection, using a murine model of wild-type (WT) and iNKT cell-deficient (Jα18⁻/⁻) C57BL/6 mice sacrificed 15, 30 or 60 days post-infection. We recorded hepatic parasite loads, cytokine expression, and analyzed granulomatous response by immunohistochemistry and hepatic immune cell infiltration by flow cytometry. Whereas WT animals rapidly controlled the infection and developed an inflammatory response associated with a massive influx of iNKT cells observed by flow cytometry, Jα18⁻/⁻ mice had significantly higher parasitic loads on all time points. This lack of control of parasite burden was associated with a delay in granuloma maturation (28.1% of large granulomas at day 60 versus 50.7% in WT). Cytokine transcriptome analysis showed that mRNA of 90/101 genes encoding chemokines, cytokines and their receptors, was underexpressed in Jα18⁻/⁻ mice. Detection of IL-4 and TNF-α by ELISA in liver extracts was also significantly lower in Jα18⁻/⁻ mice. Consistent with flow cytometry analysis, cytokinome profile in WT mice showed a bias of expression towards T cell-chemoattractant chemokines on D15, and displayed a switch towards expression of granulocytes and/or monocytes -chemoattractant chemokines on D60. In Jα18⁻/⁻ mice, the significantly lower expression of CXCL5, MIP-2 and CCL2 mRNA was correlated with a defect in myeloperoxidase positive-cell attraction observed by immunohistochemistry and with a lower granulocyte and monocyte infiltration in the liver, as shown by flow cytometry. These data indicate that iNKT cells play a role in early and sustained pro-inflammatory cytokine response warranting efficient organization of hepatic granulomas and parasite clearance.
ISSN: 1932-6203

hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897/document
https://hal.archives-ouvertes.fr/hal-00696897/file/Invariant_NKT_Cells_Drive-accepted.pdf
DOI : 10.1371/journal.pone.0033413

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Chenaillet Ophiolite in the Franco-Italian Alps represents a well-exposed ocean-floor sequence that was only weakly overprinted by Alpine metamorphism during its emplacement in the Alpine nappe stack. Pillow lavas showing a Mid Ocean Ridge Basalt (MORB) signature overlie tectonically exhumed gabbros and serpentinized mantle rocks similar to oceanic core complexes (OCC) described from present-day slow- to ultraslow-spreading ridges. Based on detailed mapping it can be shown that: 1) syn-magmatic high-temperature shear zones are truncated by oceanic detachment faults; 2) sediments consisting exclusively of clasts derived from the footwall of the detachment are overlain by voluminous lavas, and 3) emplacement of lavas is linked with high-angle faulting that overprint the oceanic detachment fault. Based on stratigraphic and cross cutting relationships we conclude that: 1) a complex relation between high- and low-temperature shear zones exists, 2) oceanic detachment faults may be obliterated by later emplaced of MOR basalts, and 3) high-angle faults may serve at shallow levels as feeder channels for the overlying pillow basalts. These observations raise questions about the relative relations in time and space between magmatic, hydrothermal and tectonic processes at spreading systems. We propose that the observed change from exhumation along an oceanic detachment fault to high-angle faulting associated with extrusion of volcanic rocks may represent an evolution within a life cycle of a spreading system that may be comparable to present-day slow- to ultraslow-spreading ridges.
ISSN: 0024-4937

hal-00617678
https://hal.archives-ouvertes.fr/hal-00617678
DOI : 10.1016/j.lithos.2010.10.017

Éditeur(s) : HAL CCSD Inter-Research
Résumé : Precise knowledge of lifetime migrations is vital in exploited fish species, since all essential habitats must be protected to maintain sustainable stock levels. The present study used multi-element otolith fingerprints of the gilthead sea bream Sparus aurata (L.) to discriminate its main juvenile and adult habitats in the Languedoc-Roussillon region (Gulf of Lions, northwest Mediterranean) and infer the lifetime migrations of 12 individuals from the area (11 from the present day and 1 from the Roman era). This allowed for the first time the identification of key habitats for the successful completion of the species' life cycle in the Gulf of Lions, and the connectivity between them. Our results revealed that lagoon use by S. aurata is probably ancient (>2500 yr) and confirmed its current commonness. Yet, although most observed migration patterns were in accordance with the migratory behavior previously described for the species, strong inter-individual variations and new patterns in habitat use were detected. At the juvenile stage, a preference for shallow lagoons with low salinities was evidenced. Nevertheless, the first year of life can also be successfully completed in marine conditions. At the adult stage, lagoon use was shown to occur until at least age 4 yr, with periods of lagoon residency of up to 11 mo in a year, often including winter months. Because overwintering in the lagoons was previously thought to be impossible for S. aurata due to low temperatures, this finding has important implications for future stock management, especially since the species breeds in winter.
Marine Ecology Progress Series

hal-00682003
https://hal.archives-ouvertes.fr/hal-00682003
DOI : 10.3354/meps09444

Éditeur(s) : HAL CCSD
Résumé : Ocean Drilling Program Hole 1256D reached for the first time the transition zone between the sheeted dike complex and the uppermost gabbros. The recovered crustal section offers a unique opportunity to study the deepest part of the hydrothermal system in present-day oceanic crust. We present a structural analysis of electrical borehole wall images. We identified, and measured the orientations of four categories of structures: major faults, minor fractures, possibly hydrothermal veins, and dikes. All structures tend to strike parallel to the paleo-ridge axis. Three major fault zones (meter thick) and dikes are steeply dipping (~ 75° on average) outward the ridge. Centimeter-thick moderately conductive planar features are interpreted as hydrothermal veins, are organized in arrays of consistent spacing, thickness, and orientation, and are dipping about 15-20° toward the ridge. This structural pattern is interpreted as an on-axis paleohydrothermal circulation system, with vertical, dike-parallel fractures, and sub-horizontal high-temperature hydrothermal veins at the base of the sheeted dike, which was subsequently rotated ~ 15° westward around a ridge-parallel, sub-horizontal axis. This rotation can be caused by upper-crustal block rotation along a listric normal fault, and/or subsidence at the ridge axis.
Ofioliti

hal-00757592
https://hal.archives-ouvertes.fr/hal-00757592
DOI : 10.4454/ofioliti.v37i1.402

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Within the framework of the international field campaign COPS (Convective and Orographically induced Precipitation Study), a large suite of state-of-the-art meteorological instrumentation was operated, partially combined for the first time. This includes networks of in situ and remote-sensing systems such as the Global Positioning System as well as a synergy of multi-wavelength passive and active remote-sensing instruments such as advanced radar and lidar systems. The COPS field phase was performed from 01 June to 31 August 2007 in a low-mountain area in southwestern Germany/eastern France covering the Vosges mountains, the Rhine valley and the Black Forest mountains. The collected dataset covers the entire evolution of convective precipitation events in complex terrain from their initiation, to their development and mature phase until their decay. Eighteen Intensive Observations Periods with 37 operation days and eight additional Special Observations Periods were performed, providing a comprehensive dataset covering different forcing conditions. In this article, an overview of the COPS scientific strategy, the field phase, and its first accomplishments is given. Highlights of the campaign are illustrated with several measurement examples. It is demonstrated that COPS research provides new insight into key processes leading to convection initiation and to the modification of precipitation by orography, in the improvement of quantitative precipitation forecasting by the assimilation of new observations, and in the performance of ensembles of convection-permitting models in complex terrain.
ISSN: 0035-9009

hal-00565513
https://hal.archives-ouvertes.fr/hal-00565513
DOI : 10.1002/qj.752

Éditeur(s) : Gauthier-Villars
Résumé : Five particle traps were deployed at depths of 4 400 to 4 900 rn at two stations on the Demerara abyssal plain and one station on the Cape Verde abyssal plain (tropical Atlantic). At the same time, an intensive sampling of superficial sediments was carried out using a 0,25 m2 box corer. The total particle flux varied from 372 to 87,7 mg dry weightfm2/day. The average concentration of organic carbon was 40 mg/g of material collected. ln the surface sediment this was only 4 mg/g. A direct relationship existed between the intensity of the flux of organic matter and the richness of the organic matter of the deposited sediment. According to our calculations, more than 90% of the organic matter arriving at the bottom is consumed by the abyssal benthos and only 1% is lost to permanent sediment deposits. For 100 calories consumed by the benthos, 99 are utilized by the infauna and flora, 0, 7 by the holothurian egafauna and 0,3 by near-bottom fisches. The biochemical composition of the particles is characterized at ali stations by a predominance of "humic" material in the total organic matter (more than 55%). The part of the molecules unaltered form living material varied from on station to another: for the most oceanic station the protein dominated, composing 20% of the total energy. At the station onder the influence of the continent the lipid fraction grew and was almost equal to that of the protein. ln this case, the carbohydrate fraction was very weak (7% of the organic matter). Finally the preference of the animais which feed on the particles is principally for the most energetic (lipid) and the most easily hydrolysable (labile protein) molecules: the other molecules, such as the humic matter, are less preferred, although they still contribute to about half of the energy consumed by the abyssal benthic animais.
Cinq pièges à particules ont été déployés à des profondeurs comprises entre 4400 et 4 900 rn sur deux stations dans la plaine abyssale de Demerara et une station dans la plaine abyssale du Cap Vert (Atlantique tropical). Dans le même temps, un échantillonnage intensif du sédiment superficiel a été réalisé à l'aide d'un carottier de 0,25 m2 d'ouverture. Le flux particulaire total mesuré varie de 372 mg de matière sèche/m2/jour à 87,7 mg/m2/g de matériel récolté. Dans les sédiments superficiels, elle n'est plus que d'environ 4 mg/g. Il existe une relation directe entre l'intensité du flux organique et la richesse en composés organiques du sédiment. D'après nos estimations, plus de 90% du matériel organique arrivant sur le fond sont consommés par les organismes benthiques abyssaux et seulement 1% est perdu dans la sédimentation permanente. Pour 100 calories consommées par le benthos, 99 le sont par la petite faune et la flore vivant dans le sédiment, 0, 7 calories sont utilisées par les holothuries (mégafaune) et 0,3 calories par les poissons. La composition biochimique des particules se caractérise, à toutes les stations, par la prédominance des composés organiques transformées néobiogéniques ( « humus ») dans la matière organique totale (plus de 55%). La part des molécules de la matière vivante varie d'une station à l'autre: à la station la plus océanique, les protéines dominent et composent 200/o de l'énergie totale des apports. Dans la station plus soumise aux influences continentales, la concentration en lipides augmente et peut égaler celle des protéines. Dans ce cas, le taux de glucides des particules est très faible (7% des apports organiques). Enfin, les préférences nutritionnelles des animaux qui s'alimentent sur ces particules se portent principalement sur les molécules les plus énergétiques (lipides) et les plus facilement hydrolysables (protéines labiles) : les autres molécules, comme les composés néobiogéniques sont moins recherchés bien qu'ils contribuent pour moitié à l'énergie consommée par les animaux benthiques abyssaux
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1985 , Vol. 8 , N. 3 , P. 293-301

Droits : Gauthier-Villars
http://archimer.ifremer.fr/doc/00112/22318/19991.pdf
http://archimer.ifremer.fr/doc/00112/22318/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Geochronological studies of samples from continuous crustal sections of fossil intra-oceanic arcs are paramount for determining the precise timing of major processes that took place during the building of an oceanic island-arc crust. In this study, laser ablation ICP-MS U-Pb zircon (and conventional Rb-Sr) analyses pinpoint the timing of major events responsible for crustal growth of the Kohistan paleo-island arc (Northern Pakistan). Inheritance in magmatic rocks is evidence for recycling of intra-arc material and indicates that the Kohistan arc may have formed as early as 135 +/- 4 Ma. One older inherited grain indicates that the arc developed on a young oceanic lithosphere whose remnants include a c. 175 Ma old component. An interesting consequence is that intra-oceanic arc magmas can yield inherited zircons, which can be much older than the arc system itself without requiring recycling back into the mantle by subduction processes. In the case of the Kohistan arc, ante-arc Neotethys oceanic lithosphere was tapped by arc magmas during their way upward into the arc crust. The oldest magmatic ages measured in this study fall in the range 101-102 Ma (100.9 +/- 0.6 and 102.1 +/- 0.4 Ma). This period corresponds to arc build-up and thickening of the arc crust. Leucogranitic melts dated at 89.9 +/- 0.4 Ma and 90.9 +/- 1.0 Ma are considered as produced by dehydration/melting reaction accompanying granulitisation of the thickened lower arc crust. A maximum age for this event is 97.7 +/- 0.7 Ma, the age of emplacement of a garnet meta-tonalite affected by granulite facies metamorphism. Magmatic activity was still ongoing during and after the granulitisation as testified by emplacement of a diorite and a gabbro dated at 89.1 +/- 0.6 and 88.2 +/- 0.9 Ma respectively. The upper part of the metaplutonic sequence contains diorite samples dated at 84.6 +/- 0.5 Ma and 84.3 +/- 0.5 Ma and as young as 81.1 +/- 0.7 Ma. During this period, and based on the present day outcropping sequences, the mean crustal growth rate varied from 32 to 65 km(3)/km/Ma (volume per unit width along the strike of the arc) which is comparable to the range for present day arcs of the Western Pacific region. The correspondence of crustal growth rates observed for present-day island arcs and the good preservation of the crustal section in the Kohistan arc, make this area an exceptional natural laboratory to study arc related processes and to check models of continental crust formation by arc accretion.
ISSN: 0012-821X

hal-00644555
https://hal.archives-ouvertes.fr/hal-00644555
DOI : 10.1016/j.epsl.2011.07.016

Éditeur(s) : HAL CCSD
Résumé : Karstic aquifers represent the most important fresh water reservoirs in many regions of the world like the Mediterranean Basin. However, because of complex processes of karstification, those aquifers are highly heterogeneous at all spatial scales and vulnerable to contamination. In this dissertation, we studied the potential of gravimetry and ambient seismic noise for hydrological modeling in karstic areas.The dolomitic area surrounding the “GEK” observatory in the Durzon catchment on the Larzac plateau, in France, is the preferred site for these studies. Inside the observatory, a superconducting gravimeter dedicated to hydrology has continuously measured gravity changes since 2011 with high precision, undertaken for the first time on a karst. From this gravity monitoring, we made conceptual hydrological models which laid the foundation of 1-D flow physical models. Indeed, gravimetry is an integrative hydro-geophysical method which allows 1) to consider the epikarst, locally heterogeneous as an equivalent tabular medium and 2) to define the types of transfer (fast & slow) occurring at the site. Especially, the lack of fast transfer through the GEK epikarst was precisely quantified for the first time at the field scale (~100m). Gravity-driven water mass balance with local meteorological data (evapotranspiration from a flux tower and precipitation) allowed setting the bottom outlet of the model to 1 mm.day-1. This flow has proved to be representative of the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. This result supposes the homogeneity of the dolomitic epikarst almost at the basin scale. Model parameters were next calibrated using one year of ambient seismic noise monitored at two stations. Phase velocity changes obtained by cross-correlating the noise between 6 and 8 Hz were used as a ”timer” to follow the water infiltration between a depth of 30 and 60 meters. Thus, monitoring seismic velocity changes using ambient seismic noise demonstrates great potential for the study of deep and complex critical zones and could fill the instrumental gap currently existing in hydrology.Time-lapse gravity measurements with a spring-based portable gravimeter have also demonstrated the different behavior of two epikarsts and their variability at the scale of a few hundred meters. Monthly measurements around the observatory revealed the spatial homogeneity of this dolomitic epikarst: all the stations showed the same water storage changes. On the contrary, seasonal surface to depth gravity measurements along the underground passage of the Saint-Ferréol sinkhole, in limestone, have shown fast transfer and strong spatial variability of water storage. Lithology is then expected to play a part in the epikarst capacity to retain water. The precision needed to measure the weak hydrological induced signals during those surveys required robust methodology and an ambient temperature effect on measurements with spring-based gravimeter was observed in the field and quantified in the laboratory.
Les aquifères karstiques représentent des ressources en eau essentielles dans de nombreuses régions du monde comme le bassin Méditerranéen. Cependant, de par les processus complexes de karstification, ces aquifères sont hétérogènes à de nombreuses échelles et vulnérables. Dans cette thèse, nous étudions le potentiel de la gravimétrie et du bruit sismique ambiant pour la modélisation hydrologique en milieu karstique.Le site dolomitique de l’observatoire « GEK », sur le bassin du Durzon dans le Larzac, est le site d’étude privilégié de ces travaux. Dans l’observatoire, un gravimètre supraconducteur dédié à l’hydrologie mesure depuis 2011 les variations de gravité en continu et à une très haute précision, pour la première fois sur un karst. Des modèles hydrologiques conceptuels ont été réalisés à partir de cette surveillance gravimétrique et ont permis de poser les bases de modèles physiques d’écoulements 1-D. En effet la gravimétrie, intégratrice, permet 1) de considérer l’épikarst localement hétérogène comme un milieu tabulaire équivalent et 2) de définir les types de transfert à l’œuvre sur le site. En particulier, l’absence de transfert rapide dans l’épikarst a été quantifiée avec précision pour la première fois à l’échelle du terrain (~100m). A l’aide de données météorologiques locales, un bilan de masse précis a permis de définir le flux en limite inférieure du modèle à 1 mm.jour-1. Ce flux s’est montré représentatif du débit de basses-eaux de la source drainant l’ensemble du bassin. Ce résultat suppose une homogénéité de l’épikarst dolomitique quasiment à l’échelle du bassin. Les paramètres des modèles physiques ont ensuite pu être calibrés à l’aide d’un an d’intercorrélation du bruit sismique ambiant entre deux stations. Les variations de vitesses de phase obtenues entre 6 et 8Hz nous ont servi de « chronomètre » pour suivre l’infiltration entre 30 et 60m de profondeur. La surveillance passive des variations de vitesses sismiques par intercorrélation du bruit sismique ambiant montre ainsi un fort potentiel pour l’étude des zones critiques profondes et complexes à l’échelle du terrain et peut combler la lacune instrumentale qui existe actuellement en hydrologie.Des campagnes répétées de mesures avec un gravimètre portable à ressort ont également mis en évidence le fonctionnement différent de deux épikarsts et leur variabilité à l’échelle de la centaine de mètres. Des mesures mensuelles autour de l’observatoire ont mis en évidence l’homogénéité spatiale de cet épikarst dolomitique : toutes les stations ont les mêmes variations temporelles de stock d’eau. Au contraire, des mesures saisonnières en surface et en profondeur le long de la galerie souterraine calcaire de l’abîme de Saint-Ferréol ont montré une variabilité spatiale forte du stockage ainsi que du transfert rapide. La lithologie de l’épikarst est donc suspectée de jouer un rôle dans sa capacité de stockage. Lors de ces campagnes, la faiblesse du signal recherché a nécessité une méthodologie précautionneuse et un effet de température sur les mesures des gravimètres relatifs à ressort a été observé sur le terrain et quantifié en laboratoire.
https://tel.archives-ouvertes.fr/tel-01649606

NNT : 2016MONTT128
tel-01649606
https://tel.archives-ouvertes.fr/tel-01649606
https://tel.archives-ouvertes.fr/tel-01649606/document
https://tel.archives-ouvertes.fr/tel-01649606/file/2016_FORES_archivage.pdf

Éditeur(s) : Elsevier
Résumé : To improve the knowledge of the survival of enteric viruses in a marine environment, the influence of physico-chemical parameters (temperature, UV, salinity) on the survival of infectious poliovirus 1 and hepatitis A Virus (HAV) in seawater was first studied, the influence of suspended solids (SS) on poliovirus adsorption and survival in seawater was then evaluated and the detection of rotavirus genome in environmental samples (shellfish, river water, treated wastewater) was finally investigated. The results show that temperature has a major impact on virus survival in seawater as the time necessary to inactivate 90 % of the virus (T-90) is 671 days at 4 degrees C and only 25 days at 25 degrees C. Ultraviolet light (42 mW s cm(-2)) rapidly inactivates viruses but HAV is more resistant (T-90 = 2.6 min) than the poliovirus 1 (T-90 = 1.3 min). By contrast, seawater salinity has no effect on virus survival. In presence of SS, 90 % to 99.9 % of the viruses were adsorbed. This adsorption does not provide any protection for viruses with low SS concentrations (3 and 15 mg L-1) but a slight increase in virus survival was observed with a high SS concentration (500 mg L-1). Finally environmental sample analysis indicated that 20 % shellfish, about 40 % river water and 40 % treated wastewater tested positive for the rotavirus genome.
Ce travail a pour but de mieux comprendre le devenir des virus en milieu marin. Dans ce cadre, l'influence de certains paramètres physicochimiques (température, UV et salinité) sur le pouvoir infectieux du poliovirus 1 et du virus de l'hépatite A (VHA) en eau de mer a été évalué, puis l'adsorption du poliovirus 1 sur les matières en suspension (MES) a été étudié, ainsi que les conséquences sur le pouvoir infectieux du virus et enfin le génome des rotavirus a été recherché en milieu naturel (eaux et coquillages). Les résultats montrent que la température est un paramètre important pour la survie des virus puisque le temps nécessaire à inactiver 90 % des virus (T90) en eau de mer est de 671 j à 4 °C alors qu'il est seulement de 25 j à 25 °C. Le rayonnement ultraviolet (42 mW s cm−2) testé en pilote expérimental, permet d'obtenir une inactivation rapide du poliovirus 1 (T90 = 1,3 min). Le VHA est plus résistant avec un T90 = 2,6 min. En revanche la salinité de l'eau de mer n'a pas d'influence sur la survie des virus. En ce qui concerne l'influence des MES, les résultats montrent qu'en présence de 3, 15 et 500 mg L−1 de Na-montmorillonite la majorité des virus est adsorbée (90 à 99,9 %). Cet état adsorbé ne procure aucune protection aux virus pour les faibles concentrations de MES (3 et 15 mg L−1) alors qu'une augmentation significative de survie est observée pour les fortes concentrations (500 mg L−1). Enfin, l'analyse d'échantillon de l'environnement a montré que 20 % des fruits de mer, environ 40 % des eaux de rivière et environ 40 % des eaux usées traitées testées contenaient du génome de rotavirus.
Oceanologica Acta (0399-1784) (Elsevier), 1998-11 , Vol. 21 , N. 6 , P. 983-992

Droits : 1998 Ifremer / CNRS / IRD - Published by Elsevier SAS
http://archimer.ifremer.fr/doc/1998/publication-846.pdf
DOI:10.1016/S0399-1784(99)80020-6
http://archimer.ifremer.fr/doc/00000/846/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self-recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts.
ISSN: 1464-7931

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01334353
https://hal-univ-perp.archives-ouvertes.fr/hal-01334353
https://hal-univ-perp.archives-ouvertes.fr/hal-01334353/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01334353/file/Green_et_al-2015-Biological_Reviews.pdf
DOI : 10.1111/brv.12155

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The brain of the adult teleost fish exhibits intense neurogenic activity and an outstanding capability for brain repair. Remarkably, the brain estrogen-synthesizing enzyme, aromatase B, is strongly expressed, particularly in adult fishes, in radial glial cells, which act as progenitors. Using zebrafish, we tested the hypothesis that estrogens affect adult neurogenesis and brain regeneration by modulating the neurogenic activity of radial glial cells. To investigate this, the estrogenic environment was modified through inhibition of aromatase activity, blockade of nuclear estrogen receptors, or estrogenic treatments. Estrogens significantly decreased cell proliferation and migration at the olfactory bulbs/telencephalon junction and in the mediobasal hypothalamus. It also appears that cell survival is reduced at the olfactory bulbs/telencephalon junction. We also developed a model of telencephalic lesion to assess the role of aromatase and estrogens in brain repair. Proliferation increased rapidly immediately after the lesion in the parenchyma of the injured telencephalon, while proliferation at the ventricular surface appeared after 48 h and peaked at 7 days. At this time, most proliferative cells express Sox2, however, none of these Sox2 positive cells correspond to aromatase B-positive radial glial cells. Interestingly, aromatase B expression was significantly reduced 48 h and 7 days after the injury, but surprisingly, at 72 h after lesion, aromatase B expression appeared de novo expressed in parenchyma cells, suggesting a role for this ectopic expression of aromatase in brain repair mechanisms. Altogether these data suggest that estrogens modulate adult, but not reparative neurogenesis, in zebrafish.
ISSN: 0018-506X

inserm-00831715
http://www.hal.inserm.fr/inserm-00831715
DOI : 10.1016/j.yhbeh.2012.04.003
PUBMED : 22521210

Éditeur(s) : HAL CCSD Cushman Foundation for Foraminiferal Research
Résumé : International audience
This study proposes a new method for fast and inexpensive extraction of a large number of living foraminifera for laboratory cultures. The method is a significant improvement over current extraction methods, which are highly time-consuming. Several treatments were designed to test the method. Sediment bearing foraminifera from Brouage Mudflat (Atlantic coast of France) was washed through a 50-µm sieve and distributed in glass Petri dishes with 20, 40 and 80 specimens of Hydrobia ulvae, a common gastropod from European intertidal mudflats. As a control experiment, one dish was treated similarly but maintained without Hydrobia. After two days, most of the sediment in the Hydrobia treatments was compacted into small cylindrical gastropod feces and the tests of living benthic foraminifera (Ammonia tepida and Haynesina germanica) were clean and easily visible. Additional experiments showed that the foraminifera were not ingested by Hydrobia ulvae, and could be picked quickly and easily.
ISSN: 0096-1191

hal-01248034
https://hal.archives-ouvertes.fr/hal-01248034
https://hal.archives-ouvertes.fr/hal-01248034/document
https://hal.archives-ouvertes.fr/hal-01248034/file/rossignol%20et%20al%202007.pdf
DOI : 10.2113/gsjfr.37.1.8

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : À la suite à d’une envolée des prix du carburant en Guyane, alors même que le cours du baril de pétrole mondial est en chute, les Guyanais s’emploient à mobiliser toute la société. En date du 24 novembre 2008, débute une manifestation contre la hausse du prix du carburant, et plus globalement contre la vie chère. La Guyane, paralysée pendant plus de dix jours au départ, connaîtra une crise qui durera près d’un an. Elle a su transformer admirablement une contestation isolée en une mobilisation collective non conventionnelle et l’inscrire dans une logique décrite au plan théorique par A. Touraine : elle a transformé une particularité en « Totalité » (revendication globale), donné au mouvement une « Identité » en propulsant à sa tête un puissant acteur de classe et entrepreneur du mouvement, désigné un « Adversaire » de classe, en l’occurrence la puissance publique avec laquelle elle partage les mêmes objectifs (peser sur l’historicité de la collectivité), mais en dispute les moyens. Deux consultations populaires ont marqué par la voie référendaire un attachement de la Guyane à la métropole (1ère consultation du 10 janvier 2010) et la volonté d’une simplification administrative des décisions (2nde consultation du 24 janvier 2010).
In 2008, fuel prices increased in French Guyana, whilst at the same time world fuel prices fell. In reaction to this the Guyanese began a protest on November 24th, 2008 against the rise of fuel prices and the high cost of living in general. Paralyzed for more than ten days during the protest, the country suffered a year long a crisis. This small isolated protest was transformed into an unconventional collective movement. The situation in Guyana can be applied to the A. Touraine’s theory of how a movement can give a country and its people an identity, which allows them to fight against the adversary. The public power with whom they share the same objectives but disagree on the means of achieving them. Two popular consultations marked the attachment of French Guyana to Metropolitan France, such as the simplification of the administration sector.
Guyane française

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.4889
http://journals.openedition.org/etudescaribeennes/4889