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 American College of Sports Medicine (ACSM)
Résumé : International audience
PURPOSE AND METHODS: To determine the effects of cycling on a subsequent triathlon run, nine male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 5 km of running (C-R), and 4) 30 min of running followed by 5 km of running (R-R). Before and 10 min after the third and fourth trials, the triathletes underwent pulmonary function testing including spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R and R-R trials, arterialized blood samples were obtained to measure arterial oxygen pressure (PaO2). During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. RESULTS: The results showed that 1) the oxygen uptake (VO2) observed during subsequent running was similar for the C-R and R-R trials; 2) the ventilatory response (VE) during the first 8 min of subsequent running was significantly greater in the C-R than in R-R trial (P < 0.05); 3) only the C-R trial induced a significant increase (P < 0.05) in residual volume (RV), functional residual capacity (FRC), and the ratio of residual volume to total lung capacity (RV/TLC); and 4) although a significant decrease (P < 0.05) in DL(CO) was noted after C-R, no difference between the two exercise trials was found for the maximal drop in PaO2. CONCLUSIONS: We concluded that 1) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle fatigue and/or exercise-induced hypoxemia, and 2) the greater VE observed during the first minute of running after cycling was due to the specificity of cycling. This reinforces the necessity for triathletes to practice multi-trial training to stimulate the physiological responses experienced during the swim-cycle and the cycle-run transitions.
ISSN: 0195-9131

hal-00720412
https://hal.univ-antilles.fr/hal-00720412
https://hal.univ-antilles.fr/hal-00720412/document
https://hal.univ-antilles.fr/hal-00720412/file/Article.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Ibituruna quartz-syenite was emplaced as a sill in the Ribeira-Aracuai Neoproterozoic belt (Southeastern Brazil) during the last stages of the Gondwana supercontinent amalgamation. We have measured the Anisotropy of Magnetic Susceptibility (AMS) in samples from the Ibituruna sill to unravel its magnetic fabric that is regarded as a proxy for its magmatic fabric. A large magnetic anisotropy, dominantly due to magnetite, and a consistent magnetic fabric have been determined over the entire Ibituruna massif. The magmatic foliation and lineation are strikingly parallel to the solid-state mylonitic foliation and lineation measured in the country-rock. Altogether, these observations suggest that the Ibituruna sill was emplaced during the high temperature (similar to 750 degrees C) regional deformation and was deformed before full solidification coherently with its country-rock. Unexpectedly, geochronological data suggest a rather different conclusion. LA-ICP-MS and SHRIMP ages of zircons from the Ibituruna quartz-syenite are in the range 530-535 Ma and LA-ICP-MS ages of zircons and monazites from synkinematic leucocratic veins in the country-rocks suggest a crystallization at similar to 570-580 Ma, i.e., an HT deformation >35My older than the emplacement of the Ibituruna quartz-syenite. Conclusions from the structural and the geochronological studies are therefore conflicting. A possible explanation arises from Ar-40-Ar-39 thermochronology. We have dated amphiboles from the quartz-syenite, and amphiboles and biotites from the country-rock. Together with the ages of monazites and zircons in the country-rock, Ar-40-Ar-39 mineral ages suggest a very low cooling rate: <3 degrees C/My between 570 and similar to 500 Ma and similar to 5 degrees C/My between 500 and 460 Ma. Assuming a protracted regional deformation consistent over tens of My, under such stable thermal conditions the fabric and microstructure of deformed rocks may remain almost unchanged even if they underwent and recorded strain pulses separated by long periods of time. This may be a characteristic of slow cooling "hot orogens" that rocks deformed at significantly different periods during the orogeny, but under roughly unchanged temperature conditions, may display almost indiscernible microstructure and fabric.
ISSN: 0040-1951

hal-00445262
https://hal.archives-ouvertes.fr/hal-00445262
DOI : 10.1016/j.tecto.2009.02.039

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Evidence of a changing environment in the catchment area of a small pond (Lansquenet, Lorraine, France) during the last millennium was provided by coupling palynology data and organic ratios [terrestrial to aquatic ratio: TAR(HC); the C29 vs. C27 sterols, C29/C27(ST); average chain length, ACL and aquatic/macrophytes ratio, Paq]. The depositional and alteration conditions of organic matter (OM) were provided by the 5α(H)-stanols/Δ5-sterols ratio. This study shows that quite simple organic ratios clearly allow identification of the different evolution steps of a watershed, from a swamp to the progressive settlement of a pond. During the swampy period, the C/N(at) (ca. 11.1), TAR(HC) (ca. 36.8), C29/C27(ST) (ca. 8.7) and Paq (<0.3) show a high contribution of allochthonous OM associated with the presence of particular aquatic and mesohygrophilous species. A woody level dated to the XIIIth century reflects the period of the settlement of the pond in a more oxic environment [5α(H)-stanol/Δ5sterol ratio <0.2]. Then, the progressive increase in aquatic input and the development of submerged and floating macrophytes are evidenced by low C/N(at) (<7.6), TAR(HC) (ca. 2.7), C29/C27(ST) (ca. 2) and high Paq (ca. 0.5), suggesting an increase in the water level and eutrophication of the pond. A second oxic event [5α(H)-stanols/Δ5sterols ratio averaging 0.16], associated with extensive OM degradation, corresponds to the most recent dredging in 2002 and reflects an important disturbance of sediments due to pond management.
ISSN: 0146-6380

hal-00758066
https://hal.archives-ouvertes.fr/hal-00758066
DOI : 10.1016/j.orggeochem.2012.06.004

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
The hematocrit-to-viscosity ratio (HVR) has been widely used has an estimate of red blood cell (RBC) oxygen transport effectiveness into the microvasculature or as an oxygen delivery index. However, no study investigated the possibility of HVR to truly reflect RBC oxygen transport effectiveness or to be an oxygen delivery index. We measured blood viscosity at high shear rate (225 s −1), hematocrit, HVR, as well as the microvascular oxyhemoglobin saturation (TOI; tissue oxygen index) by spatial resolved near-infrared spectroscopy (NIRS) at cerebral and muscle levels in three population known to have various degrees of hemorheological abnormalities: healthy subjects (AA), patients with sickle cell SC disease (SC) characterized by moderate anemia and patients with sickle cell anemia (SS) marked by severe anemia. At both the cerebral and muscle level, HVR was positively correlated with TOI (r = 0.28; p = 0.03 and r = 0.38; p = 0.003, at the cerebral and muscle level, respectively). These findings suggest that HVR probably play a key role in blood flow and hemodynamic regulation in the microvasculature, hence modulating the amount of oxygen available for tissues. Nevertheless, the strengths of the associations are weak (R 2 < 0.50), suggesting that other determinants modulate microvascular blood flow and oxygenation, such as vascular geometry and vasomotor reserve.
ISSN: 1386-0291

hal-01163460
https://hal.univ-antilles.fr/hal-01163460
DOI : 10.3233/CH-131742

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND: Sampling design is a key issue when establishing species inventories and characterizing habitats within highly heterogeneous landscapes. Sampling efforts in such environments may be constrained and many field studies only rely on subjective and/or qualitative approaches to design collection strategy. The region of Cacao, in French Guiana, provides an excellent study site to understand the presence and abundance of Anopheles mosquitoes, their species dynamics and the transmission risk of malaria across various environments. We propose an objective methodology to define a stratified sampling design. Following thorough environmental characterization, a factorial analysis of mixed groups allows the data to be reduced and non-collinear principal components to be identified while balancing the influences of the different environmental factors. Such components defined new variables which could then be used in a robust k-means clustering procedure. Then, we identified five clusters that corresponded to our sampling strata and selected sampling sites in each stratum. RESULTS: We validated our method by comparing the species overlap of entomological collections from selected sites and the environmental similarities of the same sites. The Morisita index was significantly correlated (Pearson linear correlation) with environmental similarity based on i) the balanced environmental variable groups considered jointly (p = 0.001) and ii) land cover/use (p-value<0.001). The Jaccard index was significantly correlated with land cover/use-based environmental similarity (p-value = 0.001). CONCLUSIONS: The results validate our sampling approach. Land cover/use maps (based on high spatial resolution satellite images) were shown to be particularly useful when studying the presence, density and diversity of Anopheles mosquitoes at local scales and in very heterogeneous landscapes.
BMC Ecology

pasteur-00914104
https://hal-riip.archives-ouvertes.fr/pasteur-00914104
https://hal-riip.archives-ouvertes.fr/pasteur-00914104/document
DOI : 10.1186/1472-6785-13-45
PUBMED : 24289184

Éditeur(s) : HAL CCSD Elsevier
Résumé : We report a preliminary analysis on the relationships between drainage basin structure and genetic structure of populations of the European vector of fasciolosis, Galba truncatula. In the study area, 251 snails belonging to 12 populations were collected along different ditches of a same river network. Each snail was genotyped at six variable microsatellite loci. Our results show that all sample sites are characterized by a low level of polymorphism and a very high and significant heterozygote deficiency. Our data reveal a significant genetic differentiation, even at a small scale, and failed to delimit clear patterns of isolation by euclidian distance. Our study shows that genetic differentiation significantly increases with hydrographic distance along the streams (p < 0.002), in consistence with the hypothesis that dispersion along the stream is dependent on the direction of water flow. This study shows that relationships can exist between the organization of the hydrological network and population biology of a disease vector, which has strong potential applications to drainage network management issues.
ISSN: 1567-1348

hal-00496374
https://hal.archives-ouvertes.fr/hal-00496374
DOI : 10.1016/j.meegid.2010.01.005

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND AND AIM: The impact of basal core promoter (BCP) and precore (PC) mutants of the hepatitis B virus (HBV) on liver disease severity remains controversial. The aim of the present study was to screen BCP and PC mutations in 252 HBV surface antigen (HBsAg) positive carriers in France and to assess relationships between these mutations and severe fibrosis. METHODS: Direct sequencing of the precore/core gene was used to detect A1762T/G1764A and G1757A mutations in the BCP and G1896A and G1899A mutations in the PC region. RESULTS: The prevalences of A1762T/G1764A, G1757A, G1896A, and G1899A mutations were 34.1%, 38.7%, 54.9%, and 29.3% (P < 0.001), respectively. The independent predictors of severe fibrosis (>/=F3 Metavir) were older age (P < 0.001), male gender (P = 0.012), elevated alanine aminotransferase (P < 0.001), and the double A1762T/G1764A mutant with no other mutations (P = 0.011). Interestingly, the association of the G1899A mutation with the double A1762T/G1764A mutant significantly counteracted the deleterious effect of the sole double A1762T/G1764A mutant (odds ratio [OR] = 0.28 vs. OR = 3.55, respectively, P = 0.028). CONCLUSIONS: Patients with the A1762T/G1764A mutation have a higher risk of severe fibrosis. The G1899A mutation is a protective factor against severe fibrosis that counteracted the deleterious effect of the A1762T/G1764A mutation. Finally, host phenotypic and HBV genotypic markers independently predict fibrosis severity.
Journal of gastroenterology and hepatology

hal-01477209
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01477209
DOI : 10.1111/jgh.13338
PUBMED : 26992056

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
BACKGROUND: This study examines gene-environment interaction between the MTHFR C667T polymorphism and folic acid in the etiology of orofacial clefts (OFC). We used a pooled-analytical approach on four studies that used similar methods. METHODS: We used logistic regression to analyze the pooled sample of 1149 isolated cases and 1161 controls. Fetal and maternal MTHFR C677T genotypes, and maternal periconceptional exposure to smoking, alcohol, vitamin containing folic acid and folic acid supplements were contrasted between the cleft types [non-syndromic clefts lip or without cleft palate (CL(P)) and non-syndromic cleft palate (CP)] and control groups. RESULTS: There was a reduced risk of CL(P) with maternal folic acid use (p = 0.008; OR = 0.70, 95% CI: 0.65-0.94) and with supplements containing folic acid (p = 0.028, OR = 0.80, 95% CI: 0.65-0.94). Maternal smoking increased the risk of both CL(P) (p < 10 e-3; OR = 1.62, 95% CI: 1.35-1.95) and CP (p = 0.028; OR = 1.38, 95% CI: 1.04-1.83). No significant risk was observed with either maternal or fetal MTHFR C677T genotypes. CONCLUSION: This individual participant data (IPD) meta-analysis affords greater statistical power and can help alleviate the problems associated with aggregate-level data-sharing. The result of this IPD meta-analysis is consistent with previous reports suggesting that folic acid and smoking influence OFC outcomes.
ISSN: 1542-0752

hal-00875899
https://hal.archives-ouvertes.fr/hal-00875899
DOI : 10.1002/bdra.23133
PUBMED : 23670871

Éditeur(s) : HAL CCSD Elsevier
Résumé : In this study, we assessed past and present influence of ancient mining activity on metal(loid) enrichment in sediments of a former mining watershed (Gardon River, SE France), that is now industrialized and urbanized. A sedimentary archive and current sediments were characterized combining geochemical analyses, zinc isotopic analyses and sequential extractions. The archive was used to establish local geochemical background and recorded (i) increasing enrichment factors (EFs) for Pb, Zn, Cd, Tl, Hg, As and Sb throughout the industrial era, (ii) a contamination peak in 1976 attributed to a tailings dam failure, and (iii) current levels in 2002 and 2011 similar to those of 1969, except for Sb and Hg, reflecting a persisting contamination pattern. Inter-element relationships and spatial distribution of EF values of current sediments throughout the watershed suggested that both ancient and current contamination had a common origin for Pb, Zn, Cd, Tl and As related to the exploitation of Pb/Zn mineralization while old Sb mines and coal extraction area were the main sources for Sb and Hg respectively. This prevailing mining origin was reflected for Zn by a relatively uniform isotopic composition at δ66Zn = 0.23 ± 0.03‰, although slight decrease from 0.23‰ to 0.18‰ was recorded from upstream to downstream sites along the river course in relation with the contribution of the lighter δ66Zn signature (~ 0.08‰) of acid mine drainage impacted tributaries. Results from sequential extractions revealed that the potential mobility of the studied metal(loid)s varied in the order Sb < Tl ≈ As < Zn < Pb < Cd, with an increase of the mobile pool for Cd, Pb, Zn and to a lesser extent for As and Tl associated to increased enrichment. Altogether, these results tend to demonstrate that ancient mining activity still contributes to metal enrichment in the sediments of the Gardon River and that some of these metals may be mobilized toward the water compartment.
ISSN: 0048-9697

hal-01054163
https://hal.archives-ouvertes.fr/hal-01054163
DOI : 10.1016/j.scitotenv.2014.02.078

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
Résumé : International audience
Previous studies have reported respiratory, cardiac and muscle changes at rest in triathletes 24 h after completion of the event. To examine the effects of these changes on metabolic and cardioventilatory variables during exercise, eight male triathletes of mean age 21.1 (SD 2.5) years (range 17-26 years) performed an incremental cycle exercise test (IET) before (pre) and the day after (post) an official classic triathlon (1.5-km swimming, 40-km cycling and 10-km running). The IET was performed using an electromagnetic cycle ergometer. Ventilatory data were collected every minute using a breath-by-breath automated system and included minute ventilation (V(E)), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio, ventilatory equivalent for oxygen (V(E)/VO2) and for carbon dioxide (V(E)/VCO2), breathing frequency and tidal volume. Heart rate (HR) was monitored using an electrocardiogram. The oxygen pulse was calculated as VO2/HR. Arterialized blood was collected every 2 min throughout IET and the recovery period, and lactate concentration was measured using an enzymatic method. Maximal oxygen uptake (VO2max) was determined using conventional criteria. Ventilatory threshold (VT) was determined using the V-slope method formulated earlier. Cardioventilatory variables were studied during the test, at the point when the subject felt exhausted and during recovery. Results indicated no significant differences (P > 0.05) in VO2max [62.6 (SD 5.9) vs 64.6 (SD 4.8) ml x kg(-1) x min(-1)], VT [2368 (SD 258) vs 2477 (SD 352) ml x min(-1)] and time courses of VO2 between the pre- versus post-triathlon sessions. In contrast, the time courses of HR and blood lactate concentration reached significantly higher values (P < 0.05) in the pre-triathlon session. We concluded that these triathletes when tested 24 h after a classic triathlon displayed their pre-event aerobic exercise capacity, bud did not recover pretriathlon time courses in HR or blood lactate concentration.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720432
https://hal.univ-antilles.fr/hal-00720432
https://hal.univ-antilles.fr/hal-00720432/document
https://hal.univ-antilles.fr/hal-00720432/file/Article_2.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The seismic (elastic) properties of the crust have been modelled using hypothetical polycrystals with typical crustal compositions and commonly measured petrofabrics. This modelling allows us to better evaluate and quantify the crustal contribution to splitting of teleseismic SKS-waves. Mafic rocks such as anorthosite or pyroxene-bearing gabbros have complex S-waves properties, i.e. with small shear-wave anisotropies (< 3%) and without clear relationships between the fast shear-wave polarization plane orientations and the fabric. On the other hand foliated felsic rocks such as gneisses or schists and mafic rocks such as amphibole-bearing gabbros are strongly birefringent (anisotropies greater than 5%) and exhibit clear relationships with the structure. Biotite and amphibole preferred orientations clearly play a major rote in shear-wave splitting in crustal rocks. We show strong correlations between the orientation of the foliation and the amplitude of the delay time. Maximum delay time is systematically observed for waves propagating parallel to the foliation. The fast shear-wave is furthermore polarized parallel to the foliation plane. We calculate a delay time of about 0.1-0.2 s per 10 km of crustal rocks.
ISSN: 0031-9201

hal-01389713
http://hal.univ-reunion.fr/hal-01389713
http://hal.univ-reunion.fr/hal-01389713/document
http://hal.univ-reunion.fr/hal-01389713/file/Barruol_SKS_crust_PEPI1993_hal.pdf
DOI : 10.1016/0031-9201(93)90161-2

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
To constrain the crystallization of alkaline and volatile-rich lavas present in intraplate settings, we studied the petrological features and the geochemical composition of major, trace, and volatile elements of mineral and bulk-rock of two sodalite-bearing phonolites: (1) haüyne-plagioclase-bearing Si-K-rich phonolite from Laacher See (Germany) and (2) nosean-nepheline-bearing Si-poor phonolite from Saghro (Morocco). In haüyne-bearing phonolites (55–59 wt% SiO2, K > Na, Na+K/Al = 0.96–1.08), we found that the low silica and low sodium activity promoted the early crystallization of S-rich haüyne (13.7–13.9 wt% SO3, 0.4 wt% Cl) + S-rich apatite (0.7–0.9 wt% SO3), titanite, and rare pyrrhotite followed by clinopyroxene-plagioclase-sanidine at relatively low pressure and temperature (P = 250 MPa and T = 850 °C) and oxidized condition (ΔNNO-NNO+1, where NNO is nickel-nickel oxide buffer). The crystallization of haüyne occurred at fluid-undersaturated conditions from a silicate melt with 6 wt% H2O, 0.17–0.23 wt% Cl, 0.11–0.4 wt% S, and 0.07–0.14 wt% F. Nosean-bearing phonolites from Saghro are silica-poor and peralkaline (52–54 wt% SiO2, Na > K, Na+K/Al = 1.2) and crystallized at higher P and T (300 MPa and 950 °C) and more reduced conditions (NNO) compared to haüyne-bearing phonolites. The incongruent reaction to form nosean requires high silica and Na2O activity. The mineral assemblage and composition suggest early crystallization of nepheline followed by nosean (7.8–8.8 wt% SO3; 1–1.1 wt% Cl). The sequence of crystallization is: clinopyroxene + nepheline + S-poor apatite (<0.04 wt% SO3) + pyrrhotite followed by nosean and titanite. Nosean-bearing magmas are fluid-undersaturated with relatively low volatile content (4 wt% H2O, <0.25 wt% Cl, <0.056 wt% S, 0.08–0.1 wt% F), although Cl may have exsolved during ascent and formed a fluid phase (NaCl-bearing).Both haüyne- and nosean-bearing phonolites are last equilibrated at relatively low pressure and high temperature. Haüyne and nosean crystallized at oxidized and volatile-rich pre-eruptive conditions. They record the volatile concentrations at depth and may be used as oxybarometer. The incongruent reactions involved to form haüyne and nosean suggest that phonolitic magmas became more oxidized during crystallization. The initial volatile concentrations in basanite/nephelinite magmas, from partial melting of volatile-bearing K2O-rich mantle rock, should have been one important factor influencing the crystallization of haüyne-bearing Si-K-rich phonolite and nosean-bearing Si-poor phonolite in intracontinental setting.
ISSN: 0003-004X

hal-01278067
https://hal.archives-ouvertes.fr/hal-01278067
DOI : 10.2138/am-2015-5318

Éditeur(s) : HAL CCSD
Résumé : International audience
Despite the recent interest in psychiatric illness in prison, the psychopathology of the Remire-Montjoly prison population remains largely unknown. Subject to significant population movements, French Guiana and its prison houses a very mixed population in which recent history has left a strong mark (earthquake in Haïti, civil war in Suriname, violence related to gold mining population and drug trafficking). These negative life events appear as potential vectors of psychological trauma. Additionally, strong links have been established in the literature between post-traumatic stress disorder (PTSD) and many other psychiatric disorders, including suicidal behavior and addictions. Under these conditions, we felt it essential to focus on the identification of PTSD in this sensitive population.Through adapted reception interviews, we tried to identify the PTSD, to describe by means of socio-demographic factors the studied population and to detect psychiatric comorbidities. The screening tool was the M.I.N.I. 5.0, which identifies 17 psychiatric disorders including the PTSD, based on the DSM IV definition. The target population was the prison incomers, agreeing to participate in the study, aged more than 18 years old and imprisoned between 18 January 2013 and 31 December 2013. To this date, 549 inmates were included in the study.The main result of this study was a prevalence of PTSD of 17% for incomers in detention. We found that the PTSD+ population is more likely to be female (15% against 7% p = 0.0246), which is consistent with the literature data. The M.I.N.I. 5.0 showed a higher prevalence of psychiatric disorders in the PTSD+ group. This association was confirmed in several types of pathology like mood disorders including: major depressive episode and manic or hypomanic episode, suicidal risk, some anxiety disorders including: panic disorder, obsessive-compulsive disorder and generalized anxiety disorder. Strong association was found for current major depressive episode, current manic or hypomanic episode and suicidal risk (p < 0.005).The prevalence of PTSD is very high in this study, about 24 times higher than in a general population survey using the same screening tool.A large number of comorbidities have been identified, which corresponds to those described in the literature. The specific issues of psychiatry in prison lead us to examine more specifically the significance of the results about suicide risk. A comprehensive suicide risk (sum of medium and high risk screened by the M.I.N.I.) was found in significantly more PTSD+ inmates (17% versus 7%, p = 0.005). This study supports the need for routine screening of PTSD among incomers in detention. This disease is both worrying and common in this population but the real issues are the comorbidities. Suicidal potential is among the most important issues in detention. Its evaluation should be completed by an early recognition of a PTSD.
Soumis à des mouvements de population importants, la Guyane Française et son centre pénitentiaire abritentune population métissée chez qui l’histoire récente a laissé une empreinte forte (tremblement de terre en Haïti,guerre civile au Suriname, violence liée à l’orpaillage et au trafic de stupéfiants). Ces événements de vienégatifs apparaissent comme autant de vecteurs potentiels de psychotraumatismes. Dans ces conditions, il nous a paru essentiel de mettre l’accent sur le repérage du TSPT (Trouble de Stress Post-traumatique) dans cette population sensible. A l'aide d’entretiens d’accueil dédiés nous nous sommes proposé de repérer les TSPT, de décrire sur un plan sociodémographique la population étudiée et de rechercher les comorbidités psychiatriques. Le résultat principal de cette étude était une prévalence du TSPT de 17% chez les arrivants en détention. Le MINI 5.0 a montré une prévalence plus élevée des pathologies psychiatriques dans le groupe présentant un TSPT avec un lien très fort (p<0.005) pour l’épisode dépressif majeur actuel, l’épisode (hypo)maniaque actuel et le risque suicidaire. Cette étude appuie la nécessité d’avoir un dépistage systématique du TSPT chez les arrivants en détention. Cette pathologie est à la fois fréquente dans cette population et invalidante mais ce sont ses comorbidités, dont le potentiel suicidaire, qui font tout l’enjeu d’un repérage précoce.
ISSN: 0383-6320

inserm-01421075
http://www.hal.inserm.fr/inserm-01421075
http://www.hal.inserm.fr/inserm-01421075/document
http://www.hal.inserm.fr/inserm-01421075/file/2016%2C%20Arnal%20-%20Post-Traumatic%20Stress%20Disorder%20among%20Incomers%20in%20Remire-Montjoly%20Prison%2C%20French%20Guiana.pdf
PUBMED : 27570960

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Transmission electron microscopy observations on olivine crystals deformed at moderate (≤1273 K) temperature evidenced dislocations interactions explaining the hardening observed in the experiments, but also recovery mechanisms by the absorption or emission of point defects. Thus we investigate the possibility that, at geological strain-rates, these recovery processes allow steady-state deformation by dislocation creep at low to moderate temperatures in the lithospheric mantle. We test this hypothesis using a 2.5-D dislocation dynamics (DD) model, which combines dislocation glide and recovery by climb. This model shows that diffusion-controlled recovery processes allow for steady-state deformation by dislocation creep in the lithospheric mantle at stresses <500 MPa. For stresses of 50–200 MPa, steady-state strain-rates of 10−15 s−110−15 s−1 may be attained at temperatures as low as 900 K. Fitting of the DD model produces a flow law, which represents a lower bound for the lithospheric mantle strength, since the models describe the deformation of an olivine single crystal in an easy slip orientation. Comparison of strain-rates and Moho temperatures inferred for different geodynamic environments and the predictions of this model-based flow law implies, nevertheless, that, except in incipient rifts, most of the observed deformation may be produced by stress levels ≤200 MPa, consistent with those inferred to be produced by convection. This convergence suggests that the present models, which explicitly calculate the time-dependent dislocation dynamics, may provide a correct first order estimate of the mechanical behaviour of the lithospheric mantle, which cannot be derived directly from any existing data.
ISSN: 0012-821X

hal-01277178
https://hal.archives-ouvertes.fr/hal-01277178
https://hal.archives-ouvertes.fr/hal-01277178/document
https://hal.archives-ouvertes.fr/hal-01277178/file/Boioli.pdf
DOI : 10.1016/j.epsl.2015.10.012

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Talc is a hydrous magnesium rich layered silicate that is widely disseminated in the Earth from the seafloor to over 100 km depth, in ultra-high pressure metamorphism of oceanic crust. In this paper we determine the single crystal elastic constants at pressures from 0 to 12 GPa of talc triclinic (C 1¯) and monoclinic (C2/c) polytypes using ab initio methods. We find that talc has an extraordinarily high elastic anisotropy at zero pressure that reduces with increasing pressure. The exceptional anisotropy is complemented by a negative Poisson's ratio for many directions in crystal space. Calculations show that talc is not only one of very few common minerals to exhibit auxetic behaviour, but the magnitude of this effect may be the largest reported so far for a mineral. The compression (Vp) and shear (Vs) wave velocity anisotropy is 80% and 85% for the triclinic polytype. At pressures where talc is known be stable in the Earth (up to 5 GPa) the Vp and Vs anisotropy is reduced to about 40% for both velocities, which is still a very high value. Vp is slow parallel to the c-axis and fast perpendicular to it. This remains unchanged with increasing pressure and is observed in both polytypes. The shear wave splitting (difference between fast and slow S-wave velocities) at low pressure has high values in the plane normal to the c-axis, with a maximum near the alow asterisk-axis in the triclinic and the b-axis in the monoclinic polytype. The c-axis is the direction of minimum splitting. The pattern of shear wave splitting does not change significantly with pressure. The volume fraction of talc varies between 11 and 41% for hydrated mantle rocks, but the lack of data on the crystallographic preferred orientation (CPO) precludes a detailed analysis of the impact of talc on seismic anisotropy in subduction zones. However, it is highly likely that CPO can easily develop in zones of deformation due to the platy habit of talc crystals. For random aggregates of talc, the isotropic Vp, Vs and Vp/Vs ratio have significantly lower values than those of antigorite and may explain low-velocity regions in the mantle wedge. Vp/Vs ratios are more complex in anisotropic media because there are fast and slow S-waves, resulting in Vp/Vs1 and Vp/Vs2 ratios for every propagation direction, making interpretation difficult in deformed polycrystalline talc with a CPO. Talc on the subduction plate boundary can strongly influence guided wave velocity as CPO would develop in this region of intense shearing. The very low coefficient of friction (< 0.1) of talc above 100 °C could also explain silent earthquakes at shallow depths (ca 30 km) along the subduction plate boundaries, frequently responsible for tsunami.
ISSN: 0012-821X

hal-00411481
https://hal.archives-ouvertes.fr/hal-00411481
DOI : 10.1016/j.epsl.2008.07.047

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
BACKGROUND: Human immunodeficiency virus (HIV)-infected patients have decreased immune response to vaccines. Few data are available about pandemic flu vaccination in this population. METHODS: We conducted a multicenter, patient-blinded, randomized trial in a cohort of HIV-infected adults. Patients received 2 injections 21 days apart of a AS03(A)-adjuvanted H1N1v vaccine containing 3.75 μg hemagglutinin (HA) or a nonadjuvanted H1N1v vaccine containing 15 μg HA to assess hemagglutination inhibition (HI) response and safety. RESULTS: A total of 309 patients were randomized, and 306 were vaccinated. After the first vaccine dose, HI titers ≥1:40 were observed in 93.4% of the patients in the adjuvanted group (A group) (n = 155) and in 75.5% in the nonadjuvanted group (B group) (n = 151) (P < .001); seroconversion rates were 88.8% and 71.2%, and factor increases in geometric mean titers (GMT) of 21.9 and 15.1, respectively. After 2 injections, 98.6% of patients of the A group and 92.1% of the B group demonstrated HI titers ≥1:40 (P = .018); seroconversion rates were 96.5% and 87.1%, respectively, and factor increases in GMT were 45.5 and 21.2, respectively. The majority of adverse events were mild to moderate in severity; no impact on CD4+ cell count or viral load has been detected. CONCLUSIONS: In HIV-1-infected adults, the AS03(A)-adjuvanted H1N1v vaccine yielded a higher immune response than did the nonadjuvanted one, with no impact on HIV infection.
ISSN: 0022-1899

hal-00875299
https://hal.archives-ouvertes.fr/hal-00875299
DOI : 10.1093/infdis/jir211
PUBMED : 21628666

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Bronchoalveolar lavage (BAL) is a major diagnostic tool in lung diseases, including viral respiratory infections. We aimed to better define the situations where viral tests should be performed on BAL fluid (BALF). We retrospectively studied all cases where viral tests [immunofluorescence, immunocytochemistry, viral culture, and/or polymerase chain reaction (PCR)] were performed on BALF during a period of 1 year (2008) in our institution. We compared the characteristics of patients with virus-positive versus virus-negative BALF. Of the 636 BALF samples sent to the microbiology laboratory, 232 underwent viral tests. Of these, 70 (30 %) were positive and identified 85 viruses: herpes simplex virus (HSV)-1 (n = 27), cytomegalovirus (CMV, n = 23), Epstein-Barr virus (EBV, n = 18), human herpesvirus (HHV)-6 (n = 12), respiratory syncytial virus (RSV, n = 3), rhinovirus (n = 1), and adenovirus (n = 1). The variables associated with positive viral tests on univariate analysis were immunosuppression [human immunodeficiency virus (HIV), corticosteroids >10 mg/day for ≥3 weeks, or other immunosuppressive therapy], ground-glass attenuations on computed tomography (CT) scanning, late-onset ventilator-associated pneumonia (VAP), and durations of (i) hospital stay, (ii) intensive care unit (ICU) stay, and (iii) mechanical ventilation before BAL (p < 0.01 for each comparison). On multivariate analysis, only immunosuppression [odds ratio (OR) 6.4, 95 % confidence interval (CI) [2.8-14.3], p < 0.0001] and ground-glass attenuations (OR 3.7, 95 % CI [1.8-7.7], p = 0.0004) remained associated with virus-positive BAL. None of the viral tests performed on BALF for the initial assessment of diffuse infiltrative lung disease (n = 15) was positive. PCR improved the diagnostic yield of viral tests on BALF by 50 %. Testing for viruses on BALF should be mostly restricted to immunocompromised patients with acute respiratory diseases and/or patients with unexplained ground-glass attenuations on CT scanning.
ISSN: 0934-9723

hal-00873158
https://hal.archives-ouvertes.fr/hal-00873158
DOI : 10.1007/s10096-012-1791-7
PUBMED : 23238685

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The Nile delta sedimentation constitutes a continuous high resolution (1.6 mm/year) record of Ethiopian African monsoon regime intensity. Multiproxy analyses performed on core MS27PT recovered in hemipelagic Nile sediment margin (<90 km outward of the Rosetta mouth of the Nile) allow the quantification of the Saharan aeolian dust and the Blue/White Nile River suspended matter frequency fluctuations during the last 21 cal. ka BP. The radiogenic Sr and Nd isotopes, clay mineralogy, bulk elemental composition and palynological analyses reveal large changes in source components, oscillating between a dominant aeolian Saharan contribution during the LGM and the Late Holocene (~4 to 2 cal. ka BP), a dominant Blue/Atbara Nile River contribution during the early Holocene (15 to 8.4 cal. ka BP) and a probable White Nile River contribution during the Middle Holocene (8.4 to 4 cal. ka BP). The following main features are highlighted: 1. The rapid shift from the LGM arid conditions to the African Humid Period (AHP) started at about 15 cal. ka BP. AHP extends until 8.4 cal. ka BP, and we suggest that the Ethiopian African Monsoon maximum between 12 and 8 cal. ka BP is responsible for a larger Blue/Atbara Nile sediment load and freshwater input into the Eastern Mediterranean Sea. 2. The transition between the AHP and the arid Late Holocene is gradual and occurs in two main phases between 8.4 and 6.5 cal. ka BP and 6.5 to 3.2 cal. ka BP. We suggest that the main rain belt shifted southward from 8.4 to ~4 cal. ka BP and was responsible for progressively reduced sediment load and freshwater input into the eastern Mediterranean Sea. 3. The aridification along the Nile catchments occurred from ~4 to 2 cal. ka BP. A dry period, which culminates at 3.2 cal. ka BP, and seems to coincide with a re-establishment of increased oceanic primary productivity in the western Mediterranean Sea. We postulate that the decrease in thermo-haline water Mediterranean circulation could be part of a response to huge volumes of fresh-water delivered principally by the Nile River from 12 to 8.4 cal. ka BP in the eastern Mediterranean. We propose that the large hydrological change in Ethiopian latitude could be a trigger for the 8.2 ka cooling event recorded in high latitude. Revel R., Colin C., Bernasconi S., Combourieu-Nebout N., Ducassou E., Grousset F.E., Rolland Y., Migeon S., Brunet P., Zhaa Y., Bosch D., Mascle J.,. "21,000 years of Ethiopian African moonsoon variability recorded in sediments of the western Nile deep sea fan", Regional Environmental Change,
ISSN: 1436-3798

hal-00836300
https://hal.archives-ouvertes.fr/hal-00836300