Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : The Mediterranean small-scale fleet is highly adaptive, showing a dynamic fishing intensity and strategy, and exploiting seasonal abundant resources. In this area, the aggregatory behaviour under floats of juvenile fish has been used since ancient times to exploit oceanic migratory species such as dolphinfish (Coryphaena hippurus), using Fish Aggregating anchored Devices (fads). A total of 2 300 boats are engaged in this fishery from August to December, the main fishing areas being those around Malta, Tunisia, Sicily and Majorca. The fads ( arrow right m2) are made of different cheap floating materials, and are moored in fixed places, ranging from shore waters to areas 60 miles off the coast (1 500 m depth). Each boat deploys an average of 20 to 100 fads. The gears used are special surrounding nets without purse line, and traditional purse seine nets. The fishery exploits young-of-the-year dolphinfish (<6 months old), originated by a pre-spawning migration of adults from Atlantic waters. Their catches show high annual and monthly variability, depending on the recruitment and the accessibility of recruits to the fishery. Pilotfish (Naucrates ductor) and greater amberjack (Seriola dumerili) are also exploited in this fishery as by-catch. A total of about 1 000 metric tons of dolphinfish are yearly caught mainly in September-October. The fads are historically laid in August. Recently, the fads fishing period has increased in Sicily, and the fads are laid in July, so as to catch pilotfish and greater amberjak juveniles. In recent years, the interest for this fishing method and the study of these fisheries has increased in the Mediterranean. Though the market and its seasonality limit this exploitation, this fishery is economically profitable with good revenue.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15286/12672.pdf
http://archimer.ifremer.fr/doc/00042/15286/

Éditeur(s) : Institut de Ciències del Mar de Barcelona, CSIC
Résumé : The main characteristics of the biology of bigeye scad were studied from commercial fishery catches around Reunion Island. Biometric relationships were calculated. The monitoring of size distribution, aggregated by month, allowed us to estimate the theoretical growth equation using the ELEFAN software. The von Bertalanffy growth parameters were adjusted with a seasonal modulation: L8 = 265 mm; K = 1.64 year-1; c = 0.068; ? = 0.38. The growth of the cohort was quite high during the austral summer (November-April) and decreased during the austral winter (May-October). The arrival of a new cohort with homogeneous small sizes (65 to 90 mm) in the fishery in November coincided with the disappearance of large individuals. A feature of the reproductive biology was that the sex ratio remained constant month by month and that there was no predominance of male or female even in the larger size classes. Fish were mature by April and the proportion of mature fish progressively increased until November, when the gonad-indices were the highest. The size at first maturity (L50) was reached at 215 mm (fork length). The largest specimens observed were 255 mm long (fork length). After reproduction, massive mortality occurred and few individuals survived.
Scientia Marina (0214-8358) (Institut de Ciències del Mar de Barcelona, CSIC), 2007-03 , Vol. 71 , N. 1 , P. 137-144

Droits : 2007 CSIC
http://archimer.ifremer.fr/doc/2007/publication-2335.pdf
http://archimer.ifremer.fr/doc/00000/2335/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We use first first-principle methods and the Peierls-Nabarro model to evaluate the resistance to glide, characterized by the Peierls stress, of glide systems for end-member MgSiO3 Perovskite at mantle pressures. [010](100) is the easiest glide system in Mg-Perovskite at all pressures. Peierls stresses increase systematically with pressure for all systems except [001](010), indicating the importance of lattice friction at lower mantle pressures. The ratio of the maximum Peierls stress for each system relative to the [010](100) value defines their critical resolved shear stress (CRSS). These CRSS are used in a visco-plastic self-consistent homogenization model to predict the evolution of crystal preferred orientations (CPO) during deformation of polycrystalline Mg-Perovskite. In axial compression, [100] tends to align with the compression direction, in agreement with in situ observations in axial compression experiments. In simple shear, [010] concentrates near the shear direction and (100), although more dispersed, tends to align near the shear plane, consistent with the dominant activity of the easier [010](100) system. The calculated seismic anisotropy for a 100% Mg-Perovskite aggregate using the CPO in simple shear and the elastic constants Of MgSiO3 perovskite at lower mantle pressures and temperatures is weak (>3% for P-waves with and >2% for S-waves) and decreases with increasing temperature and pressure. P-waves show the fastest propagation parallel to the lineation and S-waves fast polarization is in the foliation at 38 GPa and normal to the lineation at 88 GPa. This weak anisotropy is consistent with global seismological observations of a nearly isotropic lower mantle. There are however two regions where strain-induced Mg-Perovskite CPO could contribute to anisotropy; a) low temperature regions in the uppermost lower mantle, where the predicted S-wave polarization anisotropy may attain 1.6% with a fast polarization parallel to the foliation, b) in high high-temperature domains in the D '' layer, where Mg-Perovskite may be the major stable phase, leading to polarization of fast S-waves normal to the lineation for propagation directions at high angle to the lineation and an apparent isotropy for all other propagation directions.
ISSN: 0012-821X

hal-00411460
https://hal.archives-ouvertes.fr/hal-00411460
DOI : 10.1016/j.epsl.2008.03.058

Résumé : Les travaux de recherche présentés dans ce mémoire s'inscrivent dans la lignée des approches de modélisation hydrologiques prédictives dirigées par les données. Nous avons particulièrement développé leur application sur le contexte difficile des phénomènes de crue éclairs caractéristiques des bassins versants de la région Caraïbe qui pose un dé fi sé.curi taire. En envisageant le problème de la prévision de crues comme un problème d'optimisation combinatoire difficile nous proposons d'utiliser la notion de métaneuristiques, à travers les algorithmes évolutionnaire notamment pour leur capacité à parcourir efficacement de grands espaces de recherche et fi fournir des solutions de bOlIDe qualité en des temps d'exécution raisonnables. Nous avons présenté l'approche de prédiction AV2D : Aggregate Variable Data Driven dom le concept central est la notion de variable agrégée. L'idée sous-jacente à ce concept est de considérer le pouvoir prédictif de nouvelles variables définies comme le résultat de fonctions tatistiques, dites d'agrégation calculées sur de donnée' correspondant à des périodes de temps précédent uo événem nt à prédire. Ces variable sont caractérisées par des ensembles de paramètres correspondant a leur pJ:opriétés. Nous avons imroduitle variables agrégées hydrométéorologiques permettant de répondre au problème de la classification d événements hydrologiques. La complexité du parcours de l'espace de recherche engendré par les paramètres définissant ces variables a été prise en compte grâce à la njse en oeuvre d'un algorithme évolutionnaire particulier dont les composants ont été spécifiquement définis pour ce problème. Nous avons montré, à travers une étude comparative avec d'autres approches de modélisation dirigées par les données, menée sur deux cas d'études de bassins versant caribéens, que l'approche AV2D est particulièrement bien adaptée à leur contexte. Nous étudions par la suite les bénéfices offerts par les approches de modélisation hydrologiques modulaires dirigées par les données, en définissant un procédé de division en sous-processus prenant en compte les caractéristiques paniculières des bassins versants auxquels nous nous intéressons. Nou avons proposé une extension des travaux précédents à travers la définition d'une approche de modélisation modulaire M2D: Spatial Modular Data Driven, consistant à considérer des sous-processus en divisant l'ensemble des exemples à classifier en sous-ensembles correspondant à des comportements hydrologiques homogènes. Nous avons montré à travers une étude comparative avec d autres approches dU'igées par les données mises en oeuvre sur les mêmes sous-ensembles de données que celte approche permet d améliorer les résultats de prédiction particulièrement à coun Lenne. Nous avons enfin proposé la modélisation d un outil de pi
The work presented in this thesis is in the area of data-driven hydrological modeling approaches. We particularly investigared their application on the difficult problem of flash flood phenomena typically observed in Caribbean watersheds. By considering the problem of flood prediction as a combinatorial optimization problem, we propose to use the notion of Oleraheuristics, through evolutionary algorithms, especially for their capacity ta visit effjciently large search space and to provide good solutions in reasonable execution times. We proposed the hydrological prediction approach AV2D: Aggregate Variable Data Driven which central concept is the notion of aggregate variable. The underlying idea of this [concept is to consider the predictive power of new variables defined as the results of statistical functions, called aggregation functions, computed on data corresponding ta time periods before an event ta predict. These variables are characterized by sets of parameters corresponding ta their specifications. We introduced hydro-meteorological aggregate variables allowing ta address the classification problem of hydrological events. We showed through a comparative study on two typical caribbean watersheds, using several common data driven modelling techniques that the AV2D approach is panicul.rly weil fitted ta the studied context. We also study the benefits offered by modulaI' approaches through the definition of the SM2D: Spatial Modular DataDriven approach, consisting in considering sub-processes partly defined by spatial criteria. We showed that the results obtained by the AV2D on these sub-processes allows to increase the performances particularly for short term prediction. Finally we proposed the modelization of a generic control tool for hydro-meteorological prediction systems, H2FCT: Hydro-meteorological Flood Forecasting Control 1'001

http://www.theses.fr/2013AGUY0673/document

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Leg ulcer is a disabling complication in patients with sickle cell anemia (SCA) but the exact pathophysiological mechanisms are unknown. The aim of this study was to identify the hematological and hemorheological alterations associated with recurrent leg ulcers. Sixty-two SCA patients who never experienced leg ulcers (ULC-) and 13 SCA patients with a positive history of recurrent leg ulcers (ULC+) - but with no leg ulcers at the time of the study - were recruited. All patients were in steady state condition. Blood was sampled to perform hematological, biochemical (hemolytic markers) and hemorheological analyses (blood viscosity, red blood cell deformability and aggregation properties). The hematocrit-to-viscosity ratio (HVR), which reflects the red blood cell oxygen transport efficiency, was calculated for each subject. Patients from the ULC+ group were older than patients from the ULC- group. Anemia (red blood cell count, hematocrit and hemoglobin levels) was more pronounced in the ULC+ group. Lactate dehydrogenase level was higher in the ULC+ group than in the ULC- group. Neither blood viscosity, nor RBC aggregation properties differed between the two groups. HVR was lower and RBC deformability tended to be reduced in the ULC+ group. Our study confirmed increased hemolytic rate and anemia in SCA patients with leg ulcers recurrence. Furthermore, our data suggest that although systemic blood viscosity is not a major factor involved in the pathophysiology of this complication, decreased red blood cell oxygen transport efficiency (i.e., low hematocrit/viscosity ratio) may play a role.
ISSN: 1932-6203

inserm-00922105
http://www.hal.inserm.fr/inserm-00922105
http://www.hal.inserm.fr/inserm-00922105/document
http://www.hal.inserm.fr/inserm-00922105/file/2013_Connes_-_Decreased_Hematocrit.pdf
DOI : 10.1371/journal.pone.0079680

Éditeur(s) : HAL CCSD
Résumé : International audience
Modelling techniques for river hydrologic forecasting systems have taken advantage of machine learning methods especially for flood prediction. But current solutions, mostly based on artificial neural networks do not always meet end users requirements on the readability and the understandability of predictive models. In this paper, we present a new version of our original solution based on the concept of aggregate variables in order to predict flash flood events from observed water level and/or rain measurements, particularly in the context of caribbean watersheds in which flash flood are much uncertain. We combine aggregate variables in juries. Juries of aggregate variables are trained and tested using a typical 10-fold cross validation scheme. Best juries are searched through an evolutionary approach that is optimized. Different parameters are set up like aggregation periods and jury sizes to prove the efficiency of the proposed approach compared to classical solutions.
Congress on Evolutionary Computation (CEC) 2013
Cancun, Mexico

hal-00847582
https://hal.archives-ouvertes.fr/hal-00847582
DOI : 10.1109/CEC.2013.6557656

Éditeur(s) : HAL CCSD IWA Publishing
Résumé : International audience
UV spectrophotometry is largely used for water and wastewater quality monitoring. The measurement/estimation of specific and aggregate parameters such as nitrate and dissolved organic carbon (DOC) is possible with UV spectra exploitation, from 2 to multi wavelengths calibration. However, if nitrate determination from UV absorbance is known, major optical interferences linked to the presence of suspended solids, colloids or dissolved organic matter limit the relevance of UV measurement for DOC assessment. A new method based on UV spectrophotometric measurement of raw samples (without filtration) coupling a dual pathlength for spectra acquisition and the second derivative exploitation of the signal is proposed in this work. The determination of nitrate concentration is carried out from the second derivative of the absorbance at 226 nm corresponding at the inflexion point of nitrate signal decrease. A short optical pathlength can be used considering the strong absorption of nitrate ion around 210 nm. For DOC concentration determination the second derivative absorbance at 295 nm is proposed after nitrate correction. Organic matter absorbing slightly in the 270-330 nm window, a long optical pathlength must be selected in order to increase the sensitivity. The method was tested on several hundred of samples from small rivers of two agricultural watersheds located in Brittany, France, taken during dry and wet periods. The comparison between the proposed method and the standardised procedures for nitrate and DOC measurement gave a good adjustment for both parameters for ranges of 2-100 mg/L NO3 and 1 30 mg/L DOC. (C) 2016 Elsevier Ltd. All rights reserved.
ISSN: 0043-1354

hal-01460742
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01460742
DOI : 10.1016/j.watres.2016.11.010
PUBMED : 27838025

Éditeur(s) : HAL CCSD European Geosciences Union (EGU)
Résumé : International audience
We consider here wind speed time series and the aggregate output wind power from a wind farm. We study their scaling statistics in the framework of fully developed turbulence and Kolmogorov's theory. We estimate their Fourier power spectra and consider their scaling properties in the physical space. We show that the atmospheric wind speed and the aggregate power output from a wind farm are intermittent and multifractal over a wide range of scales. The coupling between simultaneous data of the wind speed and aggregate power output is investigated through a joint multifractal description using the generalized correlation functions (GCFs). This multiscaling test is compatible with a linear relation between the wind speed and the aggregate power output fluctuations for timescales T > 103 s ' 15min.
ISSN: 1023-5809

hal-00958490
https://hal.archives-ouvertes.fr/hal-00958490
DOI : 10.5194/npg-21-379-2014

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Approximately 4,000 petroleum (oil and gas) platforms exist in the northern Gulf of Mexico and form one of the world's most extensive de facto artificial reef systems. Collectively, these structures may comprise one of the largest fad (Fish Aggregating Device) arrays in the world, attracting surface and midwater pelagic fishes. The diverse composition of pelagic fish fauna at ngom platforms is described and includes valued species such as Thunnus albacares, Thunnus atlanticus, Coryphaena hippurus, Acanthocybium solandri, Rachycentron canadum, Seriola dumerili, Scomberomorus cavalla, and Decapterus punctatus. Petroleum platforms influence pelagic fishery resources and are an important component of the Gulf's commercial and recreational fishing industries. Reviewed literature revealed a sparsity of fundamental knowledge of densities, temporal and spatial occurrence, and fishing effort/catch rates of pelagic fishes at platforms. The role of Gulf petroleum platforms "as fads" is examined, possible mechanisms for aggregation are reviewed, and a synopsis of the author's preliminary findings on life history aspects of A. solandri and R. canadum from platforms is presented. It is proposed that platforms provide opportunities for the study of pelagic species to better understand the life history, ecology, behaviour, and habitat requirements of pelagic fishery resources in the Gulf of Mexico.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15301/12633.pdf
http://archimer.ifremer.fr/doc/00042/15301/

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Hydrogen can be stored in the structure of nominally anhydrous minerals as point defects, and these impurities substantially modify many physical properties of Earth's mantle minerals. However, mantle rocks are composed of mineral grains separated by grain boundaries and interphase grains boundaries. Therefore, as a potential hydrogen reservoir, grain boundaries should be given proper attention. Here, I report an experimental investigation into hydrogen diffusion through grain boundaries in polycrystalline aggregates Sintering and diffusion experiments were performed using a gas-medium high-pressure vessel at under pressure of 300 MPa and over a temperature range of 900-1,250 degrees C. The diffusion assembly consisted of a polycrystalline cylinder of aluminous spinel + olivine crystals with a talc cylinder as the main hydrogen source. A Ni capsule was used to buffer the oxygen fugacity at Ni-NiO Experimental durations varied from 5 min to 5 h. The presence of hydrogen in the crystals was measured by Fourier-transform infrared spectroscopy. The calculation of the diffusion coefficients was based on the estimation of the characteristic distance. The absence or presence of hydrogen recorded by the 'hydrogen sensor' olivines embedded in the aggregate allows the estimation of bounds on this characteristic distance. Results presented here suggest that hydrogen effective diffusion coefficients are only one order of magnitude faster (similar to 10(-9) m(2)s(-1) at 1,000 degrees C) than in an olivine single crystal along the [100] axis. Resulting diffusion coefficients for hydrogen in grain boundary are four orders of magnitude faster than in a single crystal, but this diffusivity is not fast enough to affect hydrogen mobility in mantle rocks with grain sizes greater than similar to 1 mm. Thus, very limited chemical homogenization would occur using grain boundaries diffusion in mantle hydrous peridotite for incompatible and volatile element, such as hydrogen.
ISSN: 0010-7999

hal-00564353
https://hal.archives-ouvertes.fr/hal-00564353
DOI : 10.1007/s00410-010-0512-4

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Objectives To investigate the association between priapism in men with sickle cell anemia (SCA) and hemorheological and hemolytical parameters. Materials and Methods Fifty-eight men with SCA (median age: 38 years) were included; 28 who had experienced priapism at least once during their life (priapism group) and 30 who never experienced this complication (control group). Twenty-two patients were treated with hydroxycarbamide, 11 in each group. All patients were at steady state at the time of inclusion. Hematological and biochemical parameters were obtained through routine procedures. The Laser-assisted Optical Rotational Cell Analyzer was used to measure red blood cell (RBC) deformability at 30 Pa (ektacytometry) and RBC aggregation properties (laser backscatter versus time). Blood viscosity was measured at a shear rate of 225 s(-1) using a cone/plate viscometer. A principal component analysis was performed on 4 hemolytic markers (i.e., lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT), total bilirubin (BIL) levels and reticulocyte (RET) percentage) to calculate a hemolytic index. Results Compared to the control group, patients with priapism exhibited higher ASAT (p = 0.01), LDH (p = 0.03), RET (p = 0.03) levels and hemolytic indices (p = 0.02). Higher RBC aggregates strength (p = 0.01) and lower RBC deformability (p = 0.005) were observed in patients with priapism compared to controls. After removing the hydroxycarbamide-treated patients, RBC deformability (p = 0.01) and RBC aggregate strength (p = 0.03) were still different between the two groups, and patients with priapism exhibited significantly higher hemolytic indices (p = 0.01) than controls. Conclusion Our results confirm that priapism in SCA is associated with higher hemolytic rates and show for the first time that this complication is also associated with higher RBC aggregate strength and lower RBC deformability.
ISSN: 1932-6203

hal-01390971
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01390971
DOI : 10.1371/journal.pone.0154866
PUBMED : 27145183

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper presents the background for the calculation of anisotropic piezoelectric properties of single crystals and the graphical display of the results in two or three dimensions, and the calculation of the aggregate properties from constituent crystals and the texture of the aggregate in a coherent manner. The texture data can be obtained from a wide range of sources, including pole figure diffraction and single orientation measurements (electron backscattered diffraction, electron channelling pattern, Laue Pattern, optical microscope universal-stage). We consider the elastic wave propagation in piezoelectric crystals as an example of the interaction of electrical (2nd rank tensor), piezoelectric (3rd rank tensor) and elastic properties (4th rank tensor). In particular, we give explicit formulae for the calculation of the Voigt averaged tensor from individual orientations or from an orientation distribution function. For the latter we consider numerical integration and an approach based on the expansion into spherical harmonics. We illustrate the methods using single crystals, polycrystalline quartz measured using electron channelling patterns and ideal Curie limiting groups applied to quartz aggregates. This paper also serves as a reference paper for the mathematical tensor capabilities of the texture analysis software MTEX
Geological Society Special Publication, 409

hal-01277789
https://hal.archives-ouvertes.fr/hal-01277789
DOI : 10.1144/SP409.2

Éditeur(s) : HAL CCSD IOS Press
Résumé : International audience
Little is known about the impact of blood rheology on the occurrence of retinopathy in sickle cell disease (SCD). Fifty-nine adult SCD patients in steady-state condition participated to the study: 32 with homozygous SCD (sickle cell anemia; SCA) and 27 with sickle cell hemoglobin-C disease (SCC). The patients underwent retinal examination and were categorized according to the classification of Goldberg: 1) no retinopathy (group 1), 2) non-proliferative or proliferative stage I-II retinopathy (group 2) and 3) proliferative stage III-IV-V retinopathy (group 3). Hematological and hemorheological (whole blood viscosity, RBC deformability and aggregation properties) measurements were performed for each patient. In the whole SCD group (SCA + SCC patients) and in SCC patients, the group 3 had higher platelets count than group 2 but the difference between group 3 and group 1 did not reach statistical significance. No difference was observed for the other parameters between the three groups. SCC patients from the group 3 exhibited higher whole blood viscosity than SCC patients from the group 1. No significant difference was observed between the three groups in SCA patients. This study revealed that severe sickle proliferative retinopathy is associated with blood hyperviscosity in SCC patients but not in SCA patients.
ISSN: 1386-0291

inserm-00849032
http://www.hal.inserm.fr/inserm-00849032
http://www.hal.inserm.fr/inserm-00849032/document
http://www.hal.inserm.fr/inserm-00849032/file/inserm-00849032.pdf
DOI : 10.3233/CH-2012-1622

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Marine Protected Areas (MPAs) are increasingly used for biodiversity conservation and the management of sustainable fisheries. The use of taxonomic surrogates in routine monitoring of the reserve effects on fish assemblages may represent a promising method due to its substantial technical and economic benefits. However, higher taxonomic ranks should be used as surrogates with caution, especially for fish, where the approach is still virtually undocumented. This study aims to shed light on relationships between taxonomic relatedness and ecological similarity, which is crucial to assess the relevance of species surrogacy to reflect species-level information and detect changes in fish related to protection regimes. By analyzing data from a Mediterranean MPA, we show that rather being related to taxonomic relationships, the ability of higher taxa to reflect species-level patterns was explained in terms of aggregation level and distribution of species within taxa. Null models using random aggregations of species were created to identify the best surrogates able to depict changes in responses of assemblages to protection observed at the species-level. Comparison of null model predictions with the more classical higher-taxon approach revealed that the latter was not reliable because, unlike null model outcomes, surrogates determined empirically were not relevant for other subsequent independent monitoring. The effectiveness of species surrogates to depict changes in responses of assemblages to protection observed at the species-level depended (1) on the numerical resolution of the aggregation and (2) the magnitude of differences between protected and unprotected locations. Such findings suggest that surrogacy approaches may be applied for routine monitoring of Mediterranean reef fish communities, although mere empirical determinations of sufficient taxonomy seems to be not reliable, legitimizing the use of alternative methods based on null models. Guidelines for the careful use of species surrogacy in the ecological evaluation of MPAs on fish assemblages are provided.
ISSN: 0006-3207

hal-01174428
https://hal-univ-perp.archives-ouvertes.fr/hal-01174428
DOI : 10.1016/j.biocon.2015.06.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
To better understand the microstructural evolution of a "serpentinized" mantle rock and the influence of various hydrous phases on the seismic properties of the mantle wedge, we have conducted the detailed microstructural analyses of a sample of tremolite-chlorite-antigorite schist collected from the Moses Rock dike (central part of the Colorado Plateau). We performed differential effective media (DEM) modelling to study the effect of three hydrous phases forming two-phase aggregates with olivine, considering the crystallographic preferred orientation (CPO) of each phase and the shape ratio of the hydrous phases. We have demonstrated that in a partially serpentinized peridotite, the olivine CPO characteristic of [100](010) dislocation glide is still preserved, and the high-temperature asthenospheric flow is preserved with a foliation normal to that of antigorite schist. The transformation of olivine into antigorite occurs predominantly (~ 75%) by the relationship (100)ol || (001)atg with [001]ol || [010]atg, with the (010)ol || (001)atg and [001]ol || [010]atg relationship observed in areas of weak antigorite CPO. Chlorite results from the phase transformation of olivine in a relatively static environment, as shown by the correlation between the olivine-chlorite CPOs with (100)ol || (100)ch, (010)ol || (001)ch and (001)ol || (010)ch. The fluid percolation that caused the localized metasomatism and partial hydration of the mantle occurred possibly along trans-lithospheric shear zones. The presence of chlorite induces the most important drop on the P-wave velocities and may help to explain some local low velocities in the fore-arc mantle wedges, but is unlikely to be of global importance due to its very high Vp/Vs ratio ~ 1.9. On the other hand, antigorite is the only phase that causes important modification on the propagation directions of P and S-waves, and the only phase to explain the polarization of the fastest shear waves parallel to the subduction trench.
ISSN: 0040-1951

hal-00858061
https://hal.archives-ouvertes.fr/hal-00858061
DOI : 10.1016/j.tecto.2013.03.022

Éditeur(s) : HAL CCSD Ferrata Storti Foundation
Résumé : International audience
BACKGROUND: Little is known about the effects of blood rheology on the occurrence of acute chest syndrome and painful vaso-occlusive crises in children with sickle cell anemia and hemoglobin SC disease. DESIGN AND METHODS: To address this issue, steady-state hemorheological profiles (blood viscosity, red blood cell deformability, aggregation properties) and hematologic parameters were assessed in 44 children with sickle cell anemia and 49 children with hemoglobin SC disease (8-16 years old) followed since birth. Clinical charts were retrospectively reviewed to determine prior acute chest syndrome or vaso-occlusive episodes, and rates of these complications were calculated. RESULTS: Multivariate analysis revealed that: 1) a higher steady-state blood viscosity was associated with a higher rate of vaso-occlusive crises in children with sickle cell anemia, but not in children with hemoglobin SC disease; 2) a higher steady-state red blood cell disaggregation threshold was associated with previous history of acute chest syndrome in children with hemoglobin SC disease and boys with sickle cell anemia. CONCLUSIONS: Our results indicate for the first time that the red blood cell aggregation properties may play a role in the pathophysiology of acute chest syndrome in children with hemoglobin SC disease and boys with sickle cell anemia. In addition, whereas greater blood viscosity is associated with a higher rate of vaso-occlusive crises in children with sickle cell anemia, no association was found in children with hemoglobin SC disease, underscoring differences in the etiology of vaso-occlusive crises between sickle cell anemia and hemoglobin SC disease.
ISSN: 0390-6078

inserm-00849038
http://www.hal.inserm.fr/inserm-00849038
http://www.hal.inserm.fr/inserm-00849038/document
http://www.hal.inserm.fr/inserm-00849038/file/inserm-00849038.pdf
DOI : 10.3324/haematol.2012.066670

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
MR and MDHD contributed equally to this work. Summary Painful vaso-occlusive crisis, a hallmark of sickle cell anaemia, results from complex, incompletely understood mechanisms. Red blood cell (RBC) damage caused by continuous endogenous and exogenous oxidative stress may precipitate the occurrence of vaso-occlusive crises. In order to gain insight into the relevance of oxidative stress in vaso-occlusive crisis occurrence , we prospectively compared the expression levels of various oxidative markers in 32 adults with sickle cell anaemia during vaso-occlusive crisis and steady-state conditions. Compared to steady-state condition, plasma levels of free haem, advanced oxidation protein products and myeloperoxi-dase, RBC caspase-3 activity, as well as the concentrations of total, neutrophil-and RBC-derived microparticles were increased during vaso-occlusive crises, whereas the reduced glutathione content was decreased in RBCs. In addition, natural anti-band 3 autoantibodies levels decreased during crisis and were negatively correlated with the rise in plasma advanced oxidation protein products and RBC caspase-3 activity. These data showed an exacerbation of the oxidative stress during vaso-occlusive crises in sickle cell anaemia patients and strongly suggest that the higher concentration of harmful circulating RBC-derived microparticles and the reduced anti-band 3 autoantibodies levels may be both related to the recruitment of oxidized band 3 into membrane aggregates.
ISSN: 0007-1048

inserm-01476067
http://www.hal.inserm.fr/inserm-01476067
http://www.hal.inserm.fr/inserm-01476067/document
http://www.hal.inserm.fr/inserm-01476067/file/2016%2C%20Hierso%20-%20Exacerbation%20of%20oxidative%20stress%20during%20sickle%20vaso-occlusive%20crisis.pdf
DOI : 10.1111/bjh.14476

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Studies performed in the last decades have highlighted the need to better understand the contribution of the endothelium, vascular function, oxidative stress, inflammation, coagulation, hemolysis and vascular adhesion mechanisms to the pathophysiology of acute vaso-occlusive like events and chronic organ damages in sickle cell disease (SCD). Although SCD is a hemorheological disease, a few works focused on the contribution of blood viscosity, plasma viscosity, red blood cell deformability and aggregation in the pathophysiology of SCD. After a brief description of basic hemorheology, the present review focuses on the role of the hemorheological abnormalities in the causation of several SCD complications, mainly in sickle cell anemia and hemoglobin (Hb) SC disease. Several genetic and cellular modulators of blood rheology in SCD are discussed, as well as unresolved questions and perspectives.
ISSN: 0268-960X

hal-01668334
https://hal.univ-antilles.fr/hal-01668334
DOI : 10.1016/j.blre.2015.08.005

Éditeur(s) : Actes de colloque Ifremer n°28, 2000. ISBN-13 978-2-84433-047-5 ISBN-10 978-2-84433-047-5
Résumé : The international symposium "Tuna Fishing and Fish Aggregating Devices " , October 1999, in Martinique, takes stock of the exploitation of large pelagic fish around FADs, based on regional synthesis for the three oceans and the Mediterranean Sea. Main themes include technology, fishing methods, impact on resources, biology of fish aggregation, anthropology and economic aspects of FAD exploitation. The meeting will gather and disseminate results from recent and ongoing studies on FADs in the different oceans of the world, enhance collaboration between scientists and managers involved in the development of FADs, promote the emergence of scientific and technical research, form a network for cooperation and enhance communications between researchers in the different locations concerned.
Le colloque international « Pêche thonière et dispositifs de concentration de poissons» organisé en octobre 1999, en Martinique, permet de dresser un bilan, sous forme de synthèses régionales, de l'exploitation des grands poissons pélagiques à l'aide de DCP dans les trois océans et en Méditerranée. La technologie, les méthodes de pêche, l'impact sur les ressources, le comportement agrégatif des poissons et les aspects socio-économiques de l'utilisation des DCP sont les principaux thèmes développés. Ces travaux permettront d'assurer une diffusion large des résultats à l'échelle de l'océan mondial, de favoriser les échanges entre les scientifiques et les gestionnaires impliqués dans le développement des systèmes DCP, de promouvoir l'émergence de thèmes et projets de recherche scientifique et technologique, de mettre en oeuvre un réseau de communication et d'échanges entre les sites et les régions concernées.

Droits : 2000 Ifremer
http://archimer.ifremer.fr/doc/00042/15326/12646.pdf
http://archimer.ifremer.fr/doc/00042/15326/

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

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