Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
BACKGROUND: HIV cohort collaborations, which pool data from diverse patient cohorts, have provided key insights into outcomes of antiretroviral therapy (ART). However, the extent of, and reasons for, between-cohort heterogeneity in rates of AIDS and mortality are unclear. METHODS: We obtained data on adult HIV-positive patients who started ART from 1998 without a previous AIDS diagnosis from 17 cohorts in North America and Europe. Patients were followed up from 1 month to 2 years after starting ART. We examined between-cohort heterogeneity in crude and adjusted (age, sex, HIV transmission risk, year, CD4 count and HIV-1 RNA at start of ART) rates of AIDS and mortality using random-effects meta-analysis and meta-regression. RESULTS: During 61 520 person-years, 754/38 706 (1.9%) patients died and 1890 (4.9%) progressed to AIDS. Between-cohort variance in mortality rates was reduced from 0.84 to 0.24 (0.73 to 0.28 for AIDS rates) after adjustment for patient characteristics. Adjusted mortality rates were inversely associated with cohorts' estimated completeness of death ascertainment [excellent: 96-100%, good: 90-95%, average: 75-89%; mortality rate ratio 0.66 (95% confidence interval 0.46-0.94) per category]. Mortality rate ratios comparing Europe with North America were 0.42 (0.31-0.57) before and 0.47 (0.30-0.73) after adjusting for completeness of ascertainment. CONCLUSIONS: Heterogeneity between settings in outcomes of HIV treatment has implications for collaborative analyses, policy and clinical care. Estimated mortality rates may require adjustment for completeness of ascertainment. Higher mortality rate in North American, compared with European, cohorts was not fully explained by completeness of ascertainment and may be because of the inclusion of more socially marginalized patients with higher mortality risk.
ISSN: 0300-5771

hal-00875138
https://hal.archives-ouvertes.fr/hal-00875138
DOI : 10.1093/ije/dys164
PUBMED : 23148105

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) : HAL CCSD M.L.M.S. Publisher
Résumé : International audience
This paper deals with educational language policy in the French overseas department of Guiana regarding the introduction of regional languages and cultures in school. It provides analyzes of recent official discourses of the Educational institution, of ordinary discourses of different social actors as well as a critical insight into the school's and future teachers' curricula. Taking into account sociolinguistic results in French Guiana, we discuss two main points in the present policy: the distinction drawn between regional languages and other languages and the distinction drawn between so-called “heterogeneous” and ethnically and linguistically “homogenous” schools.
Cet article traite de la politique linguistique éducative actuellement en vigueur en Guyane Française concernant la prise en compte des langues et cultures régionales dans ce département d'Outre Mer. Au travers d'une analyse des discours officiels de l'institution scolaire, des différentes actions mises en place dernièrement et des discours ordinaires des enseignants sur le terrain, il interroge les politiques actuellement en œuvre. S'appuyant sur des résultats d'enquêtes sociolinguistiques et sur un point de vue didactique, il critique un traitement doublement différencié : entre certaines langues « dites régionales » depuis leur mention dans le rapport Cerquiglini et les autres, et entre des publics scolaires dits « hétérogènes » et ceux considérés comme ethniquement et linguistiquement « homogènes ».
ISSN: 1626-3154

halshs-00181072
https://halshs.archives-ouvertes.fr/halshs-00181072
https://halshs.archives-ouvertes.fr/halshs-00181072/document
https://halshs.archives-ouvertes.fr/halshs-00181072/file/01_ml102005_alby_leglise1.pdf

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Introduction Bien que les îles de la Caraïbe présentent des caractéristiques historiques, culturelles et économiques similaires, leur urbanisation et leur évolution démographique révèlent des discontinuités majeures. De façon générale, l’urbanisation est contrastée, ce qui conforte l’idée selon laquelle ces espaces insulaires sont des objets hétérogènes, en dépit de leurs critères historiques et culturels homogènes (Note de l’auteur). Les mutations socioéconomiques observées ont des incidence...
Caraïbes

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.342
http://journals.openedition.org/etudescaribeennes/342

Éditeur(s) : HAL CCSD
Résumé : Red blood cell hemodynamics influence blood rheology and thus circulatory function. Different authors showed that red blood cells are heterogeneous in blood flow. This heterogeneity could be explained by physical characteristics such as morphology, aggregability and deformability, but also by cellular and molecular environment. All these notions are found in sickle cell disease where sickle red blood cells become more rigid, leading to vascular occlusions, increased with an inflammatory context. In a preceding study, our results showed that velocity heterogeneity allow RBC classification, leading to different RBC sub-groups, using a dynamical approach and flow studies. In order to have a better understanding of the physiological meaning of such an heterogeneity, dynamical velocity experiences have been conducted in the case of normal and sickle red blood cells with different endothelial activations by proinflammatory cytokines, under a constant venular flow. Thus, normal and sickle red blood cells are classified into different sub-groups, showing their heterogeneity. Moreover, sub-population velocities and distribution evolve differently according to vascular state or treatment. These results show that red blood cell velocities and rheology depend on vascular environment and red blood cell morphology. However, the physiological meaning of this behavior should be explained by cellular and molecular effects of such activation.
https://hal.archives-ouvertes.fr/hal-00201461

hal-00201461
https://hal.archives-ouvertes.fr/hal-00201461
https://hal.archives-ouvertes.fr/hal-00201461/document
https://hal.archives-ouvertes.fr/hal-00201461/file/RBCV_Marianne_v1.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We use a strike-slip fault analog model to study experimentally the role played by along-fault non-uniform and asymmetric applied normal stress on both coseismic slip and long-term fault behavior. Our model is based on a visco-elasto-plastic multi-layered rheology that allows to produce several hundreds of scaled analog microquakes and associated seismic cycles. Uniform or heterogeneous applied normal stress along the fault plane is imposed and maintained constant during the whole experiment durations. Our results suggest that coseismic slip patterns are strongly controlled by spatial normal stress variations and subsequent accumulated shear stress along fault strike. Major microquakes occur preferentially in zones of major shear stress asperities. Coseismic slip distributions exhibit a pattern similar to the along-fault applied normal stress distribution. The occurrence of isolated low to moderate microquakes where residual stresses persist around secondary stress asperities, indicates that stress conditions along the fault also control the whole variability of fault slip events. Moreover, when fault slip stability conditions are modulated by normal stress distribution, our experiments suggest that the along-fault stress heterogeneity influences the seismic cycle regularity and, consequently, long-term fault slip behavior. Uniform applied normal stress favors irregular seismic cycles and the occurrence of earthquakes clustering, whereas non-uniform normal stress with a single high amplitude stress asperity generates strong characteristic microquake events with stable return periods. Together our results strengthen the assumption that coseismic slip distribution and earthquake variability along an active fault may provide relevant information on long term tectonic stress and could thus improve seismic hazard assessment.
ISSN: 0012-821X

hal-01666379
https://hal.archives-ouvertes.fr/hal-01666379
DOI : 10.1016/j.epsl.2017.10.009

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : La question que pose cet article est : comment un individu cosmopolite, à partir du geste réflexif de s’éprouver dans le regard de l’autre, peut-il saisir et se représenter son appartenance à une commune humanité ? Nous proposons que la socialisation cosmopolite soit intimement liée à la nature du groupe d’accueil dans lequel se fait l’immersion dans un ailleurs. Or, cette rencontre ne peut se faire avec l’humanité en général, mais elle prend forme dans l’interrelation entre deux ou plusieurs entités culturelles spécifiques. Ce qui nous ouvre à d’autres questions : de quelle altérité parle-t-on ? Pour qui ? Pourquoi ? Pour quoi ? De ce fait, le sentiment d’appartenance à une commune humanité, s’il est, au moins dans une certaine mesure, partagé par tout individu cosmopolite, l’est à entendre d’un point de vue utopique. Si la socialisation cosmopolite dans des enclaves backpacker ou des dispositifs d’échanges universitaires est réalisée dans une logique d’intégration principalement dirigée vers une communauté occidentale cosmopolite, une autre forme de socialisation, par l’expérience de la grande itinérance, serait ainsi possible. Cette dernière serait immergée dans les cultures locales, elle serait éphémère, aléatoire, hétérogène et principalement réalisée dans le rite des hospitalités, et peut ainsi représenter une forme différente d’élaboration du sentiment cosmopolite. En effet, celle-ci ne serait pas élaborée dans la tension entre deux modèles (intégration), mais dans une réaction en chaine de multiples modèles, qui, par sérendipités, se travaillent les unes les autres, dans de multiples directions, sans pouvoir se fixer, ouvrant ainsi à la diversité de l’humanité. S’il faut ici parler de socialisation cosmopolite, elle serait plutôt à entendre sur le plan anthropologique qu’ethnologique.
The question raised by this article is: how a cosmopolitan individual, from the reflective gesture of experiencing himself in the gaze of the other, can grasp and represent his belonging to a common humanity. We propose that cosmopolitan socialization be intimately linked to the nature of the host group in which the immersion takes place. However, this encounter cannot be made with humanity in general, but it takes shape in the interrelationship between two or more specific cultural entities. What opens us to others questions: what kind of otherness are we talking about? For whom? Why? In which purpose? As a result, the feeling of belonging to a common humanity, if it is shared, at least to some extent, by each cosmopolitan individual, is to be understood from a utopian point of view. If cosmopolitan socialization in backpacker enclaves or academic exchanges is carried out in the logic of integration mainly directed towards a cosmopolitan Western community, then another form of socialization through the experience of itinerancy would be possible. The latter would be immersed in local cultures, it would be ephemeral, random and heterogeneous and mainly carried out in the rite of hospitalities, and may thus represent a different form of elaboration of cosmopolitan feeling. Indeed, this would not be elaborated in the tension between two models (integration), but in a chain reaction of multiple models, which by serendipities, work one another, in multiple directions, without being able to stabilized, opening to the diversity of humanity. If we speak here of cosmopolitan socialization, it would rather be understood on the anthropological level than on an ethnological one.

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.11283
http://journals.openedition.org/etudescaribeennes/11283

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Both flow field heterogeneity and mass transfer between mobile and immobile domains have been studied separately for explaining observed anomalous transport. Here we investigate non-Fickian transport using high-resolution 3-D X-ray microtomographic images of Berea sandstone containing microporous cement with pore size below the setup resolution. Transport is computed for a set of representative elementary volumes and results from advection and diffusion in the resolved macroporosity (mobile domain) and diffusion in the microporous phase (immobile domain) where the effective diffusion coefficient is calculated from the measured local porosity using a phenomenological model that includes a porosity threshold ( inline image) below which diffusion is null and the exponent n that characterizes tortuosity-porosity power-law relationship. We show that both flow field heterogeneity and microporosity trigger anomalous transport. Breakthrough curve (BTC) tailing is positively correlated to microporosity volume and mobile-immobile interface area. The sensitivity analysis showed that the BTC tailing increases with the value of inline image, due to the increase of the diffusion path tortuosity until the volume of the microporosity becomes negligible. Furthermore, increasing the value of n leads to an increase in the standard deviation of the distribution of effective diffusion coefficients, which in turn results in an increase of the BTC tailing. Finally, we propose a continuous time random walk upscaled model where the transition time is the sum of independently distributed random variables characterized by specific distributions. It allows modeling a 1-D equivalent macroscopic transport honoring both the control of the flow field heterogeneity and the multirate mass transfer between mobile and immobile domains.
ISSN: 0043-1397

hal-01278285
https://hal.archives-ouvertes.fr/hal-01278285
DOI : 10.1002/2015WR017645

Éditeur(s) : HAL CCSD Elsevier
Résumé : Vegetation phenology is the study of the timing of seasonal events that are considered to be the result of adaptive responses to climate variations on short and long time scales. In the field of remote sensing of vegetation phenology, phenological metrics are derived from time series of optical data. For that purpose, considerable effort has been specifically focused on developing noise reduction and cloud-contaminated data removal techniques to improve the quality of remotely-sensed time series. Comparative studies between time series composed of satellite data acquired under clear and cloudy conditions and from radiometric data obtained with high accuracy from ground-based measurements constitute a direct and effective way to assess the operational use and limitations of remote sensing for predicting the main plant phenological events. In the present paper, we sought to explicitly evaluate the potential use of MODerate resolution Imaging Spectroradiometer (MODIS) remote sensing data for monitoring the seasonal dynamics of different types of vegetation cover that are representative of the major terrestrial biomes, including temperate deciduous forests, evergreen forests, African savannah, and crops. After cloud screening and filtering, we compared the temporal patterns and phenological metrics derived from in situ NDVI time series and from MODIS daily and 16-composite products. We also evaluated the effects of residual noise and the influence of data gaps in MODIS NDVI time series on the identification of the most relevant metrics for vegetation phenology monitoring. The results show that the inflexion points of a model fitted to a MODIS NDVI time series allow accurate estimates of the onset of greenness in the spring and the onset of yellowing in the autumn in deciduous forests (RMSE <= one week). Phenological metrics identical to those provided with the MODIS Global Vegetation Phenology product (MDC12Q2) are less robust to data gaps, and they can be subject to large biases of approximately two weeks or more during the autumn phenological transitions. In the evergreen forests, in situ NDVI time series describe the phenology with high fidelity despite small temporal changes in the canopy foliage. However, MODIS is unable to provide consistent phenological patterns. In crops and savannah, MODIS NDVI time series reproduce the general temporal patterns of phenology, but significant discrepancies appear between MODIS and ground-based NDVI time series during very localized periods of time depending on the weather conditions and spatial heterogeneity within the MODIS pixel. In the rainforest, the temporal pattern exhibited by a MODIS 16-day composite NDVI time series is more likely due to a pattern of noise in the NDVI data structure according to both rainy and dry seasons rather than to phenological changes. More investigations are needed, but in all cases, this result leads us to conclude that MODIS time series in tropical rainforests should be interpreted with great caution. (C) 2013 Elsevier Inc. All rights reserved.
ISSN: 0034-4257

hal-01032407
https://hal.archives-ouvertes.fr/hal-01032407
DOI : 10.1016/j.rse.2013.01.010

Éditeur(s) : HAL CCSD
Résumé : Different applications of linear elasticity in structural geology are presented in this thesis through the development of three types of numerical computer codes. The first one uses forward modeling to study displacement and perturbed stress fields around complexly faulted regions. We show that incorporating inequality constraints, such as static Coulomb friction, enables one to explain the angle of initiation of jogs in extensional relays. Adding heterogeneous material properties and optimizations, such as parallelization on multicore architectures and complexity reduction, admits more complex models. The second type deals with inverse modeling, also called parameter estimation. Linear slip inversion on faults with complex geometry, as well as paleo-stress inversion using a geomechanical approach, are developed. The last type of numerical computer code is dedicated to restoration of complexly folded and faulted structures. It is shown that this technique enables one to check balanced cross-sections, and also to retrieve fault chronology. Finally, we show that this code allows one to smooth noisy 3D interpreted faulted and folded horizons using geomechanics.
Différentes applications de l'élasticité linéaire en géologie structurale sont présentées dans cette thèse à travers le développement de trois types de codes numériques. Le premier utilise la modélisation directe pour étudier les déplacements et champs de contraintes autour de zones faillées complexes. On montre que l'ajout de contraintes inégalitaires, telles que la friction de Coulomb, permet d'expliquer l'angle d'initiation des dominos dans les relais extensifs. L'ajout de matériaux hétérogènes et d'optimisations, telles la parallélisation sur processeurs multi-coeurs ainsi que la réduction de complexité des modèles, permettent l'étude de modèles beaucoup plus complexes. Le second type de code numérique utilise la modélisation inverse, aussi appelée estimation de paramètres. L'inversion linéaire de déplacements sur les failles ainsi que la détermination de paléo-contraintes utilisant une approche géomécanique sont développées. Le dernier type de code numérique concerne la restauration de structures complexes plissées et faillées. Il est notamment montré qu'une telle méthode permet de vérifier l'équilibre de coupes géologiques, ainsi que de retrouver la chronologie des failles. Finalement, nous montrons que ce même code permet de lisser des horizons 3D faillés, plissés et bruités en utilisant la géomécanique.
https://tel.archives-ouvertes.fr/tel-00537899

tel-00537899
https://tel.archives-ouvertes.fr/tel-00537899
https://tel.archives-ouvertes.fr/tel-00537899/document
https://tel.archives-ouvertes.fr/tel-00537899/file/thesemaerten.pdf

Éditeur(s) : HAL CCSD Publisher : Paris : Baillière [1980-. Latest Publisher : Paris : Elsevier
Résumé : National audience
Introduction Les monocytes sont constitués de populations cellulaires hétérogènes aux propriétés distinctes. Il est retrouvé une sur-représentation de la population monocytaire CD14+/CD16+ pro-inflammatoire au cours de certaines connectivites. Cette population monocytaire s’oppose aux monocytes CD14+/CD16– qui jouent un moindre rôle dans l’amplification de la réponse inflammatoire. Les monocytes et les macrophages pourraient jouer un rôle central dans les mécanismes de fibrose au cours de la sclérodermie systémique. L’association entre les manifestations cliniques de la sclérodermie systémique et les différentes populations monocytaires reste à préciser. L’objectif de cette étude « proof of concept »est d’évaluer l’association entre la population monocytaire CD14+/CD16+ et les manifestations cliniques de fibrose chez les patients sclérodermiques. Patients et méthodes Cinquante-cinq patients répondant aux critères ACR 2013 de sclérodermie systémique ont été inclus de manière consécutive de mars à juillet 2015. Les atteintes fibrosantes ont été évaluées simultanément selon les données du bilan viscéral annuel en centre de compétence : l’atteinte cutanée était évaluée cliniquement selon le score de Rodnan modifié, les patients étaient classés selon la classification de Leroy (atteinte cutanée diffuse, atteinte cutanée limitée, sine scleroderma). La présence d’une pneumopathie interstitielle diffuse était évaluée par TDM thoracique, son retentissement sur la fonction respiratoire était précisé par les épreuves fonctionnelles respiratoires (capacité pulmonaire totale, capacité vitale forcée, DLCO). La NFS réalisée le jour du bilan viscéral était traitée en hématoflow permettant de préciser les sous populations monocytaires en fonction de leur statut CD16+ ou CD16–. Les données cliniques étaient relevées en aveugle vis-à-vis des données de cytométrie en flux. Résultats 55 patients sclérodermiques ont été inclus. Le taux moyen de monocytes CD16+ était de 0,054 G/L (SD = 0,029). Les patients avec une atteinte cutanée diffuse avaient des taux significativement plus élevés de monocytes CD16+ (p = 0,021), alors que les taux de monocytes CD16–ne différaient pas entre les patients avec atteinte cutanée diffuse et cutanée limitée. Le score de Rodnan modifié était corrélé de manière significative avec le taux de monocytes CD16+ (R = 0,513, p < 0,001). Il existait une tendance à l’association entre des taux élevés de CD16+ et la présence d’une pneumopathie interstitielle diffuse détectée par TDM (p = 0,113). Il existait une corrélation négative significative (p < 0,05) entre les taux de CD16+ et les résultats des épreuves fonctionnelles respiratoires (capacité pulmonaire totale et DLCO), attestant d’une fonction respiratoire moins bonne chez les patients à taux plus élevés de monocytes CD16+. Il n’était pas retrouvé d’association entre les taux de CD16+ et les autres paramètres cliniques ou immunologiques. Discussion Cette étude « proof of concept » semble montrer une association entre des taux élevés de monocytes CD16+ et certains paramètres de gravité des atteintes fibrosantes de la maladie. En plus de leur association à la gravité des atteintes fibrosantes de la sclérodermie systémique, les taux de monocytes CD16+ pourraient également avoir un intérêt pronostique qui reste à évaluer. Des travaux in vitro ont montré que l’ajout de TGFb au milieu de culture cellulaire de monocytes induisait une augmentation de l’expression du CD16+ par ces monocytes. Les monocytes CD16+ sont également une source de production d’IL-1 bêta et de TNF alpha pro-inflammatoires. D’autres travaux in vitro ont très récemment démontré la plus grande capacité des monocytes CD16+ à se différencier préférentiellement en macrophages ayant également des propriétés pro-inflammatoires. La sous-population monocytaire CD16+ peut également être hiérarchisée en fonction de l’intensité d’expression du CD16. La place précise de ces différentes populations monocytaires dans la physiopathologie de la sclérodermie systémique reste encore à déterminer. Les liens ténus entre monocytes et macrophages, dont l’implication est maintenant reconnue au cours de la sclérodermie invitent à investiguer davantage le rôle possible du monocyte dans le cadre de cette maladie inflammatoire et fibrosante afin d’identifier d’éventuelles nouvelles cibles thérapeutiques ou marqueurs pronostiques. Conclusion Dans cette étude « proof of concept », sur un nombre restreint de patients atteints de sclérodermie systémique répondants aux critères ACR 2013, le taux de monocytes CD16+ semble corrélé avec les atteintes fibrosantes de la maladie, laissant supposer une implication possible de cette sous-population monocytaire dans la physiopathologie de cette connectivite
ISSN: 0248-8663

hal-01321851
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01321851
DOI : 10.1016/j.revmed.2016.04.253

Éditeur(s) : HAL CCSD
Résumé : This paper develops a two-way director-firm fixed effect model to study the relationship between independent directors’ individual heterogeneity and firm operating performance, using French data. This strategy allows considering and differentiating in a unified empirical framework mechanisms related to board functioning and mechanisms related to director selection. We first show that the independence status, netted out unobservable individual heterogeneity, is negatively related to performance. This result suggests that independent board members experience a strong informational gap that outweighs other monitoring benefits. However, we show that industry-specific expertise as well as informal connections inside the boardroom may help to bridge this gap. Second, we provide evidence that independent directors have higher intrinsic ability as compared to affiliated board members, consistent with a reputation-based selection process.
https://hal.archives-ouvertes.fr/hal-01060211

hal-01060211
https://hal.archives-ouvertes.fr/hal-01060211
https://hal.archives-ouvertes.fr/hal-01060211v2/document
https://hal.archives-ouvertes.fr/hal-01060211/file/cahier%202014-29.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : The correct characterization of the effective reactive transport dynamics is an important issue for modeling reactive transport on the Darcy scale, specifically in situations in which reactions are localized, that is when different reactions occur in different portions of the porous medium. Under such conditions the conventional approach of homogenizing only the porous medium chemistry is not appropriate. We consider here reactive transport in a porous medium that is characterized by mass transfer between a mobile and a distribution of immobile regions. Chemical and physical heterogeneities are reflected by distributions of kinetic reaction rate constants and residence times in the immobile zones. We derive an effective reactive transport equation for the mobile solute that is characterized by non-local physical mass transfer and reaction terms. Specifically, chemical heterogeneity is upscaled in terms of a reactive memory function that integrates both chemical and physical heterogeneity. Mass transfer limitations due to physical heterogeneity yield effective kinetic rate coefficients that can be much smaller than the volumetric average of the local scale coefficients. These results help to explain and quantify the often reported discrepancy between observed field reaction rate constants and the ones obtained under well mixed laboratory conditions. Furthermore, these results indicate that transport under physical and chemical heterogeneity cannot be upscaled separately.
ISSN: 0169-7722

hal-00617674
https://hal.archives-ouvertes.fr/hal-00617674
DOI : 10.1016/j.jconhyd.2010.06.002

Éditeur(s) : HAL CCSD Integrated Ocean Drilling Program
Résumé : In this report we present the results of laboratory measurements carried out to explore the electrical properties of gabbroic and troctolitic samples from Integrated Ocean Drilling Program (IODP) Hole U1309D in the Atlantis Massif, an oceanic core complex located at 30°N on the Mid-Atlantic Ridge. Oceanic core complexes are presumably localized in portions of heterogeneous oceanic crust that are relatively rich in igneous rocks and are the locus of significant hydrothermal activity. Electrical properties of igneous rocks are used to discuss the rocks' porosity structure as a function of mineralogy, alteration processes, and deformation. Electrical properties of the gabbroic suites sampled during IODP Expedition 304/305 can contribute to the understanding of these processes in the Atlantis Massif. We present the full suite of electrical data together with density and porosity measurements on the same suite of samples.
ISSN: 1930-1014

hal-00464179
https://hal.archives-ouvertes.fr/hal-00464179
DOI : 10.2204/iodp.proc.304305.204.2009

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study analyses the interactions between deformation and reactive fluid and melt percolation, and their effects on sub-arc mantle seismic properties based on microstructural observations on mantle xenoliths extracted by the Tubaf and Edison seamounts close to the Lihir Island, in the Papua New Guinea archipelago. These xenoliths sample an oceanic lithosphere, which has experienced high-temperature deformation in the presence of fluids or melts. This was followed by metasomatism under static conditions. Syn-kinematic percolation of reactive Si-rich melts or fluids in peridotites has produced pyroxene-enrichment, grain size reduction, and dispersion of olivine crystal preferred orientation (CPO). Fourier transform infrared spectroscopy analyses show that olivine has very low water contents (1-4 wt. ppm H2O), similar to spinel peridotites from other subduction zones. These low values may record both low water solubility in olivine at low pressure and dehydration during transport and exhumation. Water contents in pyroxenes are highly variable and likely result from spatially heterogeneous melt or fluid percolation. Analysis of olivine CPO indicates dominant activation of both (010)[100] and (001)[100] slip systems, which are characteristic of deformation under high temperature, low stress, low pressure and low to moderate hydrous conditions. Fast S-wave polarization and P- and Rayleigh propagation directions are thus parallel to the mantle flow direction. The pyroxene enrichment by melt-rock reactions is accompanied by dispersion of olivine CPO and induces a significant decrease of the maximum S-wave and P-wave anisotropy in the peridotites. The calculated seismic properties also show that the lowest Vp/Vs ratios (< 1.7) mapped in fore-arc mantle may only be explained by taking in consideration the CPO-induced elastic anisotropy of the peridotites.
ISSN: 0040-1951

hal-00950058
https://hal.archives-ouvertes.fr/hal-00950058
DOI : 10.1016/j.tecto.2013.09.024

Éditeur(s) : HAL CCSD
Résumé : While often criticized, independence remains the ultimate criterion for evaluating board composition, whether for regulators or shareholder activists. In this study, we examine the relationship between board independence and firm operating performance in a panel of French listed companies, paying particular attention to heterogeneity and endogeneity concerns. We take advantage of an original database, with a time-series dimension that can be used to mitigate heterogeneity and dynamic endogeneity issues through GMM estimators. In addition, this database can be disaggregated at the individual (director) level. This design enables us to introduce firm fixed effects and individual fixed effects in (firm) performance equations, thereby controlling for heterogeneity at the firm and individual levels. To our knowledge, this is the first paper so far to provide a systematic account on this issue for France. Our main result is to document a significant negative relationship between accounting performance and the independence status (irrespective of the person). This result supports the argument of an information gap suffered by independent board members, as developed by Adams and Ferreira (2007).
https://hal.archives-ouvertes.fr/hal-00919408

hal-00919408
https://hal.archives-ouvertes.fr/hal-00919408
https://hal.archives-ouvertes.fr/hal-00919408v2/document
https://hal.archives-ouvertes.fr/hal-00919408/file/cahier_de_recherche_2014-01.pdf

Éditeur(s) : HAL CCSD Ocean Drilling Programm
Résumé : This paper provides a summary of postcruise scientific results from Ocean Drilling Program (ODP) Leg 209 available to date, building upon shipboard observations and syntheses summarized in the Leg 209 Initial Results volume. During Leg 209, 19 holes were drilled at 8 sites along the Mid-Atlantic Ridge from 14°43´ to 15°44´N, mainly in residual mantle peridotite intruded by gabbroic rocks, in order to understand the tectonic and structural processes responsible for formation of oceanic lithosphere with abundant residual peridotite exposed on the seafloor coupled with a relatively low proportion of volcanic rocks. Based on proportions of recovered lithologies, the entire area may be underlain by mantle peridotite with ~20%–40% gabbroic intrusions and impregnations. Impregnated peridotites with olivine + two pyroxenes + plagioclase + spinel that apparently formed in equilibrium probably record crystallization from primitive mid-ocean-ridge basalt at pressures of 0.5–0.6 GPa. Metamorphic equilibria record isobaric cooling to ~1100°C at this pressure. Thus, the conductively cooled thermal boundary layer beneath the Mid-Atlantic Ridge in this region is >15 km thick. Combined crystallization and reaction with residual peridotite formed a series of impregnated peridotites recording increasing Na content at nearly constant Mg#; this process could explain some of the variation in fractionation-corrected Na (e.g., Na = 8.0) observed in mid-ocean-ridge basalts. Clinopyroxene textures and compositions record such impregnation processes, and they are particularly well documented for Site 1274. Other Leg 209 gabbroic rocks formed from extensive crystallization of highly evolved melts, indicating that a substantial proportion of melt entering the thermal boundary layer crystallizes entirely beneath the seafloor, with no volcanic equivalent. Alteration of peridotites occurred over a range of temperatures and is the result of three distinct processes: rock-dominated serpentinization with formation of brucite in olivine-rich lithologies, fluid-dominated serpentinization with formation of magnetite and no brucite, and fluid-dominated talc alteration with addition of SiO2 as well as H2O and oxygen. The latter two processes also exhibit detectable trace element metasomatism that is distinct in its character from the igneous impregnation described in the previous paragraph. Microstructures show that most residual peridotites were not ductilely deformed at temperatures less than ~1200°C. Structural and paleomagnetic data require tectonic rotations of relatively undeformed blocks; some rotations probably exceeded 60° around nearly horizontal axes parallel to the rift axis. Rotations occurred along several generations of high-temperature mylonitic shear zones extending deeper than 15 km depth and numerous faults at lower temperature. Early formed shear zones and faults were passively rotated around later features; such a process could have produced low-angle fault surfaces without slip on low-angle faults. This region provides end-member examples of processes that are common at many or most slow-spreading ridges. Osmium isotope ratios indicate an ancient history of depletion for residual peridotites from the 14°–16°N region along the Mid-Atlantic Ridge. Though depleted Os isotope ratios in peridotite have been reported elsewhere along the global ridge system, the values from this region are among the most depleted. In general, Os isotope ratios from mid-ocean-ridge basalts are systematically more radiogenic than Os isotope ratios from ridge peridotite samples, suggesting a polygenetic heterogeneous source for mid-ocean-ridge basalts. Geochemical studies of zircons from Leg 209 gabbroic rocks and impregnated peridotites, together with other ridge and arc-related zircons, indicate that ridge zircons have systematically lower fractionation-corrected U and Th concentrations compared to arc zircons. This observation provides a tool for interpreting the tectonic provenance of ancient detrital zircons and indicates an arclike provenance for Hadean detrital zircons. Geobiological studies and aerobiological studies were also undertaken during Leg 209. The geobiological work found no measurable microbial enhancement of olivine dissolution rate, possibly because the samples from Leg 209 were sterile. The aerobiological study determined that dust from North Africa, collected from the derrick of the JOIDES Resolution during Leg 209, contains a variety of abundant microorganisms.
Proceedings ODP, scientific results, 209

hal-00407966
https://hal.archives-ouvertes.fr/hal-00407966
DOI : 10.2973/odp.proc.sr.209.001.2007

Éditeur(s) : HAL CCSD Elsevier
Résumé : This contribution reports our preliminary work to determine Cu isotope ratios for various granite rocks and examine the Cu isotope systematics within granite suites. A chemical procedure, modified from Marechal [Marechal, C.N., Telouk, R and Albarede, F., 1999. Precise analysis of copper and zinc isotopic compositions by plasma-source mass spectrometry. Chemical Geology, 156(1-4): 251-273.], Was used to separate Cu from rock matrix. Quantitative recovery (100.6 +/- 1.6%), with a low total procedural blank (2.65 +/- 0.66 ng) for Cu, has been achieved, allowing Cu isotopic measurements on samples with as little as 10 ppm Cu. The Cu isotope ratios (delta Cu-65 relative to NIST SRM 976) of 32 rock samples, ranging from mafic to felsic compositions, from 3 batholiths (2 I-type, 1 S-type) from the Lachlan Fold Belt in southeastern Australia. vary from -0.46 parts per thousand to 1.51 parts per thousand. Most of them cluster around zero, With mean values for the I-type and S-type granites of 0.03 +/- 0.15 parts per thousand and - 0.03 +/- 0.42 parts per thousand (2 sigma) respectively. These data, together with Cu isotope ratios of two loess samples, provide preliminary evidence that the baseline Cu isotopic composition of the crystalline part of upper continental crust is close to zero. The tight clustering of Cu isotope ratios of rocks from the I-type suites Suggests that high-temperature magmatic processes do not produce significant Cu isotope fractionation. However, two granites with abnormally heavy Cu isotope signatures (up to 1.51 parts per thousand) appears to be the result of localized hydrothermal alteration. Measurable variation in Cu isotopic composition of the S-type granite may reflect isotopic heterogeneity in the sedimentary Source region as a result of redox processes or may be due to hydrothermal overprinting. Thus, Cu isotope geochemistry may be a useful tracer for studying hydrothermal alteration and Source heterogeneity of granitic rocks.
ISSN: 0009-2541

hal-00413130
https://hal.archives-ouvertes.fr/hal-00413130
DOI : 10.1016/j.chemgeo.2008.06.047

Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01489008
https://hal-univ-perp.archives-ouvertes.fr/hal-01489008

Éditeur(s) : HAL CCSD Wiley
Résumé : Unveiling the genetic basis of local adaptation to environmental variation is a major goal in molecular ecology. In rugged landscapes characterized by environmental mosaics, living populations and communities can experience steep ecological gradients over very short geographical distances. In lowland tropical forests, interspecific divergence in edaphic specialization (for seasonally flooded bottomlands and seasonally dry terra firme soils) has been proven by ecological studies on adaptive traits. Some species are nevertheless capable of covering the entire span of the gradient; intraspecific variation for adaptation to contrasting conditions may explain the distribution of such ecological generalists. We investigated whether local divergence happens at small spatial scales in two stands of Eperua falcata (Fabaceae), a widespread tree species of the Guiana Shield. We investigated Single Nucleotide Polymorphisms (SNP) and sequence divergence as well as spatial genetic structure (SGS) at four genes putatively involved in stress response and three genes with unknown function. Significant genetic differentiation was observed among sub-populations within stands, and eight SNP loci showed patterns compatible with disruptive selection. SGS analysis showed genetic turnover along the gradients at three loci, and at least one haplotype was found to be in repulsion with one habitat. Taken together, these results suggest genetic differentiation at small spatial scale in spite of gene flow. We hypothesize that heterogeneous environments may cause molecular divergence, possibly associated to local adaptation in E. falcata.
ISSN: 1010-061X

hal-01032412
https://hal.archives-ouvertes.fr/hal-01032412
DOI : 10.1111/jeb.12069