Éditeur(s) : Elsevier Science Bv
Résumé : Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc crust. Assimilation-Fractional Crystallization (AFC) quantitative modeling of trace element ratios and isotopic compositions requires 1% and 10% of assimilated partial melts of a mafic oceanic crust to account for the pre- and post-1960 lavas, respectively. The post-1960 lavas differ from the former lavas emitted similar to 20 years earlier by enrichments in fluid mobile elements (K, Ba, Rb ... ), Th, and Light Rare Earth Elements (LREE). We ascribe these features to slight variations in the metasomatic agent added to the sub-arc mantle and ultimately derived from the subducted lithosphere. However, the contrasting time scales involved in subducted lithosphere dehydration and magma genesis, relative to the time elapsed between eruptions of the two lava series, suggest that two different portions of mantle which have undergone slightly different metasomatism, gave birth to the Lopevi lavas. These distinct magmas are still present beneath the volcano.
Journal Of Volcanology And Geothermal Research (0377-0273) (Elsevier Science Bv), 2013-08 , Vol. 264 , P. 72-84

Droits : 2013 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00167/27801/26223.pdf
DOI:10.1016/j.jvolgeores.2013.07.005
http://archimer.ifremer.fr/doc/00167/27801/

Éditeur(s) : HAL CCSD Université des Antilles
Résumé : International audience
Considering the increasing importance of the tourist mobilities worldwide, the questioning on the interrelationships between tourism and natural resources is more current more than ever. Tourism is a powerful vehicle of territory transformations which must be comprehended though flows, practices, consumptions. It means taking of the complexity of tourist system and of identifiyng the economic, social and environmental stakes linked to the use and the exploitation of the biodiversity by this activity.
Le questionnement sur les interactions entre le tourisme et les ressources naturelles est plus que jamais d’actualité compte tenu de l’importance croissante des mobilités touristiques à travers le monde. Le tourisme est un puissant vecteur de transformation du territoire qui doit être appréhendé à travers les flux, les pratiques, les consommations. Il s’agit de prendre la mesure de la complexité du système touristique et d’identifier les enjeux économiques, sociaux et environnementaux liés à l’utilisation et l’exploitation de la biodiversité par cette activité.
ISSN: 1779-0980

Droits : http://creativecommons.org/licenses/by-nc/
hal-01625317
https://hal.archives-ouvertes.fr/hal-01625317

Éditeur(s) : HAL CCSD Presses Universitaires de France
Résumé : International audience
After a brief examination of the cleavages resulting from colonial subordination in the French West Indies, the paper analyzes the transition from identity claims to political claims and more especially two modalities of the process : the territorialization of partisan structures and the mobilization of local resources. Contradictions involved in the nationalist approach are also studied : attempts at superimposing cultural and political identities are thwarted by the insertion of social actors into a plurality of social and cultural spaces as well as by the multiplicity of allegiances and identification levels.
Après avoir abordé la question des clivages nés de la subordination coloniale dans les Antilles françaises, l’article s’intéresse au passage des revendications identitaires au politique. L’accent est mis sur deux modalités de ce processus : la territorialisation des structures partisanes et la mobilisation des ressources locales. On s’intéresse aussi aux contradictions de la démarche nationaliste : les tentatives de superposition des identités culturelle et politique sont contrariées par l’insertion des acteurs sociaux dans une pluralité d’espaces sociaux et culturels, ainsi que par la multiplicité des allégeances et des niveaux d’identification qui en découlent.
ISSN: 0046-2616

Droits : info:eu-repo/semantics/OpenAccess
hal-01675660
https://hal.univ-antilles.fr/hal-01675660
https://hal.univ-antilles.fr/hal-01675660/document
https://hal.univ-antilles.fr/hal-01675660/file/L%27espace%20politique%20%2811-2001%29_HAL.pdf
DOI : 10.3917/ethn.024.0589

Éditeur(s) : HAL CCSD American Institute of Mathematical Sciences
Résumé : International audience
In this paper, shape optimization tools are applied to coastal engineering. A barred beach protection study is described, using a new type of water wave attenuator device, namely geotextile tube, to reduce the mobilization of sediments. A global optimization algorithm, able to pursue beyond local minima, is used to search for the optimum properties of the geotextile tube. The optimal configuration is then post-validated for generated currents.
ISSN: 1531-3492

hal-00475636
https://hal.archives-ouvertes.fr/hal-00475636
DOI : 10.3934/dcdsb.2010.13.759

Éditeur(s) : HAL CCSD Cushman Foundation for Foraminiferal Research
Résumé : International audience
Benthic foraminifera are heterotrophic protists that utilize different trophic mechanisms and nutritional resources. They exhibit a wide range of trophic behaviours: selective (grazing) and indiscriminate herbivory, symbiosis, carnivory, parasitism, uptake of dissolved organic matter, passive suspension feeding and, most commonly, deposit feeding. The benthic foraminifera Ammonia tepida, previously known as an herbivore, fed as a carnivore in laboratory experiments where mobile metazoans were provided. We observed predation on the three types of metazoans provided: nematodes, copepods, and a larval gastropod. This foraminifera used its pseudopodial network to entrap the invertebrates, which were then stripped of their soft internal tissues within 24 hours. Our experiments are the first to demonstrate that Ammonia tepida, despite its limited motility, is able to utilize larger mobile animals as a food source. The great abundance of small metazoans in most marine environments suggests that they are a food source for foraminifera. Further study of foraminiferal feeding strategies will enhance our understanding of their role in marine communities.
ISSN: 0096-1191

hal-01248040
https://hal.archives-ouvertes.fr/hal-01248040
https://hal.archives-ouvertes.fr/hal-01248040/document
https://hal.archives-ouvertes.fr/hal-01248040/file/dupuy%20et%20al%202010.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
More and more animal species are endangered every day on earth. In order to study their adaptation to world and climate change and their chances of survival, numerous initiatives have been taken that mostly need human intrusion into animal communities. Today mobile devices enable researchers to go beyond this limit. In this paper, we propose an original solution that consists on a new framework for detecting individual songs in a bird population and identifying remotely by this way their collective behavior in movements without human interaction. Movement patterns are elicited by analyzing data collected via wireless sensors fitted with microphone. Whereas similar methods use mobile devices fitted on some specimens, we rather propose fixed sensors. We demonstrate that this solution provides a good answer to technical constraints assessed by the context and we discuss results of experimental simulations that allow to define optimized parameters for the architecture to be set up on the ground. Experimental results are provided and show the relative impact of different parameters such as the number of sensors or the population size on the detection rate.
Proceedings of the 8th International Conference on Advances in Mobile Computing and Multimedia (MOMM 2010)

hal-00601641
https://hal.archives-ouvertes.fr/hal-00601641

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We aim at testing and validating a mobile-immobile mass transfer model from a set of single-well injection withdrawal tracer tests in a heterogeneous porous aquifer. By varying the duration of the injection phase, different volumes of aquifer are investigated by the tracer. Hence, we focus the transport model validation not only on reproducing a single breakthrough curve (BTC) but also on the model's capacity to predict the amount of mixing as a function of the volume visited by the tracer. All the BTCs are strongly asymmetric, as expected when dispersion is controlled by diffusive mass transfers between the mobile water and the immobile water part of the porosity. However, the BTC cannot be modeled by a conventional mobile-immobile mass transfer model with a simple power law memory function. To account for that, we implement a continuous time random walk model in which the transition time distribution y (t), which is related to the excursion time probability of the tracer in the immobile domain, is a dual-slope power law distribution. The model best fits the BTC data set with a transitional regime controlled by y(t) t2 and an asymptotic regime characteristic of the conventional double-porosity model with y(t) t1.5 . This work emphasizes that high-resolution concentration measurement and multiple-scale tracer tests are required for assessing solute dispersion models in heterogeneous reservoirs and for subsequently obtaining reliable predictions.
ISSN: 0043-1397

insu-00373698
https://hal-insu.archives-ouvertes.fr/insu-00373698
https://hal-insu.archives-ouvertes.fr/insu-00373698/document
https://hal-insu.archives-ouvertes.fr/insu-00373698/file/Borgne_et_al-2008-Water_Resources_Research.pdf
DOI : 10.1029/2007WR006279

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Recent geochemical work shows that subduction-zone serpentinites are repositories for fluid-mobile elements absorbed during interaction with sediment-derived fluids. Unraveling the geochemical fingerprint of these rocks helps to define timing of tectonic accretion of sediments along the subduction interface and the role of serpentinite in element recycling to volcanic arcs. Here we present the trace element and isotopic composition (B–O–H, Sr, Pb) of high-pressure serpentinites from the Voltri Massif (Ligurian Western Alps, Italy), to discuss their role as incompatible element carriers and their contribution to recycling of sediment-derived components in subduction zones.The serpentinites presented here record metamorphic olivine growth during eclogite-facies metamorphism and show undeformed and mylonitic textures. Field relations show that undeformed rocks are enclosed in deformed ones and that no metasedimentary rocks are present nearby. Undeformed serpentinite has very high δ11BSRM951 (from +26‰ to +30‰), low Sr and Pb isotope ratios (87Sr/86Sr = 0.7053–0.7069; 206Pb/204Pb = 18.131–18.205) and low As and Sb contents (0.1 and 0.01 μg/g, respectively). Oxygen and hydrogen isotope compositions are +4.5‰ and −67‰, respectively. In contrast, mylonitic serpentinite shows lower δ11B (from +22‰ to +17‰), significant enrichment in radiogenic Sr and Pb isotopes (87Sr/86Sr up to 0.7105; 206Pb/204Pb up to 18.725), and enrichment in As and Sb (1.3 and 0.39 μg/g, respectively). δ18O of the mylonitic serpentinites reaches values of +5.9‰, whereas δD is comparable with that of undeformed rocks (approximately −70‰). In mylonitic serpentinites, the B and Sr isotopic values and the fluid-mobile element (FME) concentrations are near those for the Voltri metasedimentary rocks (calc- and mica-schists). Pb systematics also reveal influx of a crust-derived component.Our dataset shows that undeformed serpentinite still preserves an oceanic geochemical fingerprint, whereas mylonitic serpentinite is reset in its concentrations of FME and its B, Sr and Pb isotope compositions, due to interaction with sediment- and crust-derived fluids. The environment of this interaction is either compatible with (i) an outer-rise zone setting, with percolation of seawater-derived fluids enriched in sedimentary components into bending-related fault structures, or with (ii) subduction channel domains, where ascending sediment-derived slab fluids infiltrate slices of former oceanic serpentinite accreted to the plate interface domain. Influx of sediment-derived subduction fluids along major deformation zones in serpentinite modifies the element budget of the rocks, with important implications for element recycling and the tectonic history of serpentinite. The B, Sr and Pb isotopic systematics, coupled with FME concentration in serpentinites are particularly helpful geochemical tracers of interaction between different reservoirs in subduction-interface environments, and are more sensitive than the traditionally applied stable oxygen and hydrogen isotope compositions.
ISSN: 0016-7037

hal-01419940
https://hal.archives-ouvertes.fr/hal-01419940
DOI : 10.1016/j.gca.2016.06.034

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : Geochemistry, Geophysics, Geosystems, v. 9, p. Q12001, 2008. http://dx.doi.org/10.1029/2008GC002098
International audience
Rb/Sr, 40Ar/39Ar, and Sm/Nd isotopic data are reported in Caledonian eclogites from the Lindås Nappe, Bergen Arcs, Norway, in order to investigate processes controlling isotopic equilibrium at mineral scale in polymetamorphic rocks. The Bergen Arcs exposes Sveconorwegian ∼950–930 Ma granulites, partially overprinted by Caledonian eclogite-facies metamorphism at ∼425 Ma and amphibolite-facies metamorphism at ∼410 Ma. Geochemical and Rb-Sr data from more than 10 phengite fractions separated from one sample reflect the composition of the microdomain (a few hundred microns in size) in which phengite crystallized. Phengite crystallized after garnet or plagioclase by dissolution-precipitation processes yield apparent age between 700 and 600 Ma. At the time of their crystallization, these phengites inherited the isotopic composition of their precursor minerals, at a microdomain scale. Phengite from quartz veins, which crystallized from elements mobilized by the circulating fluid, yield an age closer to the eclogite-facies metamorphic age. The closed system evolution of the eclogitizing fluid, the segregation of textural and reactional microdomains, the high Sr content of the studied phengite, and the short duration of the recrystallization processes (<1Ma) are interpreted as the main factors responsible for the lack of a Rb/Sr isotopic equilibrium, at the scale of hand samples. Such equilibrium is nevertheless reached in quartz veins where the crystallization of minerals implies that the fluid circulation acted as a factor of isotopic homogenization. The in situ single mineral Ar/Ar datings revealed that both eclogite- and amphibolite-facies minerals are characterized by an excess of radiogenic argon (ages between 425 and 520 Ma). The excess of argon has been inherited from the previous granulite and has been only partially evacuated from the system by the circulating fluid. The apparent Sm/Nd ages from garnets inherited from the granulite-facies metamorphism (c. 930 Ma) are in agreement with previous estimates. This result confirms that the diffusion of Nd in garnet does not occur at temperatures lower than 700°C. This study highlights the complexity of radiochronometer behavior during HP metamorphism and demonstrates that coupling different radiochronometers, such as Ar/Ar and Rb/Sr, does not always guarantee the validity of the geochronological results.
ISSN: 1525-2027

hal-00407885
https://hal.archives-ouvertes.fr/hal-00407885
DOI : 10.1029/2008GC002098

Éditeur(s) : Elsevier
Résumé : The accumulation of nine heavy metals in fine-grained sediments from the mangrove fringed coast of French Guiana is evaluated. The dynamic features of the South American tropical coastline, from the Amazon to the Orinoco Rivers, result in mangrove sediments being alternately submitted to phases of erosion and net sedimentation a few tens of years long. This process influences the distribution of the heavy metals associated with these frequently re-mobilized deposits. Sedimentary cores and mangrove plant samples were collected, at different seasons, in various swamps characterized by different properties (content of sedimentary organic matter, distance from sea water and fresh water). The ranges of measured concentrations expressed in mu mol g(-1) were the following: Cu (0.06 to 0.61), Co (0.12 to 0.68), Pb (0.08 to 0.18), Ni (0.32 to 0.76), Cr (0.61 to 1.40), Zn (1.25 to 5.94), Mn (4.36 to 45.4) and Fe (441 to 1128). No differences were found between sediments from mangroves developing upstream and downstream of urban areas, i.e. Cayenne and Kourou. This suggests that the content of mangrove sediments in heavy metals along the coastline of French Guiana is essentially the result of the continuous alternation of accumulation and transport phases occurring upstream after departing from the Amazon watershed. The sources of this heavy metals content are thus difficult to identify. However it is well known that the alluvium produced by the natural erosion of the Amazonian soils is naturally enriched in mercury. Also, the run-off from gold mining activities is known to contribute to mercury pollution. Ranges in total Hg were between 0.15 and 2.57 nmol g(-1), with mean values close to 0.41 nmol g(-1), and were clearly correlated with total organic carbon except for some outstanding high values, which may be a result of rapid geochemical changes. Heavy metal concentrations showed variations with depth. The redox conditions and the decay processes affecting the organic matter control the cycling of iron and manganese, which in turn control the concentrations and associations of heavy metals. These preliminary results suggest that the variations in heavy metal content with depth or between mangrove areas result largely from diagenetic processes rather than changes in metal input resulting from local human activities. (c) 2005 Elsevier B.V. All rights reserved.
Marine Chemistry (0304-4203) (Elsevier), 2006 , Vol. 98 , N. 1 , P. 1-17

Droits : 2005 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2006/publication-1041.pdf
DOI:10.1016/j.marchem.2005.06.001
http://archimer.ifremer.fr/doc/00000/1041/

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
Many epidemiological studies examining long-term health effects of exposure to air pollutants have characterized exposure by the outdoor air concentrations at sites that may be distant to subjects' residences at different points in time. The temporal and spatial mobility of subjects and the spatial scale of exposure assessment could thus lead to misclassification in the cumulative exposure estimation. This paper attempts to fill the gap regarding cumulative exposure assessment to air pollution at a fine spatial scale in epidemiological studies investigating long-term health effects. We propose a conceptual framework showing how major difficulties in cumulative long-term exposure assessment could be surmounted. We then illustrate this conceptual model on the case of exposure to NO₂ following two steps: (i) retrospective reconstitution of NO₂ concentrations at a fine spatial scale; and (ii) a novel approach to assigning the time-relevant exposure estimates at the census block level, using all available data on residential mobility throughout a 10- to 20-year period prior to that for which the health events are to be detected. Our conceptual framework is both flexible and convenient for the needs of different epidemiological study designs
ISSN: 1660-4601

hal-01296781
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01296781
DOI : 10.3390/ijerph13030319
PUBMED : 26999170

Éditeur(s) : HAL CCSD
Résumé : International audience
Les plages sableuses constituent une frontière mobile et poreuse entre l'océan ouvert et la terre. La compréhension de la circulation dans les nappes de plage est importante pour une variété de processus physiques, biologiques et chimiques. On cherche à caractériser in-situ la dynamique souterraine sous la zone de swash. Le site atelier est la plage microtidale de Rousty (Camargue, France). L'étude, réalisée sur 48h les 13 et 14 décembre 2014, fait partie d'une plus grande campagne de mesure visant à caractériser la réponse hydro-morphologique de la plage de Rousty à une saison hivernale. La période présentée ici correspond à la phase de déclin d'une tempête modérée. La stratégie retenue dans le cadre de ce projet a été de déployer un réseau de15 capteurs de pression enterrés sous la zone de swash. Les caractéristiques des vagues incidentes, à la fois au large et dans la zone de surf interne, ont été mesurées conjointement à l'utilisation d'un LiDAR terrestre haute fréquence permettant de suivre la surface libre et l'évolution du lit sableux à haute fréquence sur la zone de swash. L'analyse des données moyennées dans le temps a mis en évidence la présence d'un schéma de circulation relativement robuste sous la zone de swash, qui se décale vers le large en suivant la descente du niveau moyen et la diminution de l'activité des vagues. La tendancedominante est un écoulement vers le large, avec une intensité maximale de l'ordre de 0.1mm/s modulé par des infiltrations et exfiltrations dans les parties hautes et basses de la zone de swash, respectivement. L'analyse haute fréquence à des événements de swash sélectionnés ont mis en évidence uncycle souterrain caractéristique.
XIV èmes Journées Nationales Génie Côtier – Génie Civil
toulon, France

hal-01357778
https://hal.archives-ouvertes.fr/hal-01357778

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Mobile-immobile mass transfer is widely used to model non-Fickian dispersion in porous media. Nevertheless, the memory function, implemented in the sink/source term of the transport equation to characterize diffusion in the matrix (i.e., the immobile domain), is rarely measured directly. Therefore, the question can be posed as to whether the memory function is just a practical way of increasing the degrees of freedom for fitting tracer test breakthrough curves or whether it actually models the physics of tracer transport. In this paper we first present a technique to measure the memory function of aquifer samples and then compare the results with the memory function fitted from a set of field-scale tracer tests performed in the same aquifer. The memory function is computed by solving the matrix diffusion equation using a random walk approach. The properties that control diffusion (i.e., mobile-immobile interface and immobile domain cluster shapes, porosity, and tortuosity) are investigated by X-ray microtomography. Once the geometry of the matrix clusters is measured, the shape of the memory function is controlled by the value of the porosity at the percolation threshold and of the tortuosity of the diffusion path. These parameters can be evaluated from microtomographic images. The computed memory function compares well with the memory function deduced from the field-scale tracer tests. We conclude that for the reservoir rock studied here, the atypical non-Fickian dispersion measured from the tracer test is well explained by microscale diffusion processes in the immobile domain. A diffusion-controlled mobileimmobile mass transfer model therefore appears to be valid for this specific case.
ISSN: 0043-1397

insu-00373705
https://hal-insu.archives-ouvertes.fr/insu-00373705
https://hal-insu.archives-ouvertes.fr/insu-00373705/document
https://hal-insu.archives-ouvertes.fr/insu-00373705/file/Gouze_et_al-2008-Water_Resources_Research.pdf
DOI : 10.1029/2007WR006690

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Serpentinites are one of the major components of the oceanic lithosphere and are stable in the slab and the mantle wedge up to 100-150 km depth in subduction zones. During oceanic mantle hydration and alteration, they trap trace and fluid mobile (FME: B, Li, As, Sb, Rb, Ba, Cs, Sr, U and Pb) elements that participate to elemental transfer occurring between the dehydrating slab and the mantle wedge in subduction context. The Lanzo massif is an eclogitized oceanic lithosphere that preserved its oceanic structure and recorded different steps of serpentinization/de-serpentinization from oceanic lizardite to prograde antigorite in subduction context, up to its dehydration and secondary olivine crystallization, and finally retrograde antigorite during massif exhumation. It constitutes a suitable place to study trace element behavior during serpentinization/de-serpentinization processes and associated chemical transfers between the different envelopes of the oceanic lithosphere and the mantle wedge. Geochemical analyses of serpentine and associated minerals show that the serpentinization/de-serpentinization of the Lanzo massif took place in a relatively closed system without significant trace element transfer between the different parts of the oceanic lithosphere. In the deeper part of the lithosphere, from the slightly serpentinized mantle peridotites (SSP, < 20% serpentinization) to the paleo-Moho, composed of massive serpentinites (MS, 80% serpentinization), the trace elements mobility is reduced. The chemical composition of lizardite and antigorite is homogenized with the local degree of serpentinization: in SSP, serpentine veins composition is inherited from the host mineral while, in MS, their composition is homogenous between destabilized phases at the scale of the outcrop (~ 5 m). In the shallowest part of the oceanic lithosphere, from the paleo-Moho to the oceanic paleo-seafloor, the serpentinites are foliated (FS, > 90% serpentinization). In that zone, the alpine deformation enhances the mobility of trace elements and permits their redistribution and the homogenization of antigorite composition at massif scale. Locally, in the SSP and MS, the crystallization of metamorphic veins of ~ 1-2 m corresponds to channelized fluid flows that allowed fluid transfers - and thereby trace elements - to longer distance. The successive crystallizations of antigorite and then olivine are accompanied by a diminution of some FME (B, Li, As, Sb, Ba, Rb) and Eu contents attesting that these elements are removed from slab to mantle wedge during subduction.
ISSN: 0009-2541

hal-00937661
https://hal.archives-ouvertes.fr/hal-00937661
DOI : 10.1016/j.chemgeo.2013.08.025

Éditeur(s) : HAL CCSD
Résumé : Indigenous territories comprise extensive areas of tropical forest and hold significant social and conservation value. Today, they are subject to various constraints and opportunities, and face many territorial transformations. These transformations are complex and multifaceted. They involve the adoption of new production and consumption modes, the modification of forms of social organisation and identity and territorial claims. However, the links between these on-going processes are still poorly understood, and make difficult to appreciate the adaptation dynamics of indigenous common natural resources management. This thesis is particularly concerned with the territorial dynamics of the Wayãpi and Teko indigenous people of the municipality of Camopi in French Guiana. It integrates methods that include land use analysis using remotely sensed data, socio-economic and agricultural systems analysis at the household scale, and empirical analysis on the influence of identity claims, kinship networks, and conservation policies. It shows that despite the residential settlement around local towns, the growth of cash income from wage labour and welfare, associated with strong kinship networks, allows the revival of mobility and the diversification of indigenous territorialities. Environmental policies implemented on the territory involve processes of identity and territorial claims and motivate the construction of a collective project of endogenous local development. A comparative approach with the situation of the wayãpi people living in Brazil and evolving in a completely different institutional, socio-economic and environmental context shows similar dynamics. Indigenous peoples of these two sites adopt "multi-local" land use systems, allowing them to extend their territory occupation and taking part of a broader dynamic of territorial and identity affirmation. They articulate forest and local town environments. This multi-local land use system can be interpreted as a new form of environmental governance, which overcomes the access difficulties to natural resources around local towns and ensures their sovereignty over the territory.
Les territoires amérindiens couvrent de vastes étendues de forêts tropicales et possèdent une forte valeur sociale et environnementale. Soumis à des contraintes et opportunités variées, ils sont de nos jours le siège de nombreuses transformations territoriales. Ces transformations sont complexes et multiformes. Elles impliquent l'adoption de nouveaux modes de production et de consommation, le réajustement des formes d'organisation sociale et des dynamiques de réaffirmation identitaire et territoriale. Or les liens entre tous ces processus sont encore mal compris, et rendent délicate la compréhension des dynamiques d'adaptation des systèmes amérindiens de gestion des ressources communes. Cette thèse s'intéresse particulièrement aux dynamiques territoriales des Amérindiens wayãpi et teko de la commune de Camopi en Guyane française. Elle intègre des données sur l'occupation du sol obtenues par télédétection, des données socio-économiques et productives à l'échelle des ménages et des données qualitatives sur les processus identitaires, les réseaux de parenté, les politiques de conservation et la gouvernance du territoire. Elle montre que malgré la sédentarisation de l'habitat autour des bourgs locaux, la croissance des revenus monétaires issus des emplois salariés et des aides sociales, combinée avec le maintien de réseaux de parenté et d'entraide, permet une redynamisation des systèmes de mobilité et une diversification des territorialités amérindiennes. De plus, les politiques environnementales mises en place sur le territoire impliquent des processus de territorialisation et de revendications identitaires et motivent la construction collective d'un projet de développement local endogène. Une approche comparative avec la situation des Amérindiens wayãpi vivant au Brésil et évoluant dans un contexte socio-économique, institutionnel et environnemental bien différent montre des dynamiques similaires. Les Amérindiens de ces deux pays adoptent des systèmes d'exploitation du territoire multi-locaux, leur permettant d'étendre leur occupation du territoire et s'inscrivant dans une dynamique de réaffirmation identitaire et territoriale. Ils articulent ainsi les espaces de la forêt et des bourgs. Cette forme d'exploitation multi-locale du territoire peut être interprétée comme une nouvelle forme de gouvernance environnementale, qui leur permet de contourner les difficultés d'accès aux ressources naturelles autour des bourgs et d'affirmer leur souveraineté sur le territoire.
https://tel.archives-ouvertes.fr/tel-00831619

tel-00831619
https://tel.archives-ouvertes.fr/tel-00831619
https://tel.archives-ouvertes.fr/tel-00831619/document
https://tel.archives-ouvertes.fr/tel-00831619/file/These_TRITSCH_mai2013_vf.pdf

Éditeur(s) : INRA : Institut National de la Recherche Agronomique Université des Antilles. Service commun de la documentation Caribbean Food Crops Society (CFCS)
Extrait de : 52e congrès annuel de la Société caribéenne des plantes alimentaires / 52nd annual meeting of the Caribbean food crops society (CFCS), du 10 au 16 juillet 2016. INRA, CFCS
Description : Farmers are very inventive, but their innovations often remain confined to their farm, or to small local networks. And the interest they might have for farmers other than their inventors is seldom analyzed. Tracking on-farm innovations aims at finding technical or organizational innovations designed by farmers, to characterize their agronomic, economic and environmental performance and analyze the conditions in which this performance is expressed. The talk presents the various stages of this tracking approach, applied to innovative cropping systems, basing on a variety of recent works, in France, Argentine, Burkina Faso and China: (1) Defining what we are looking for; (2) Identifying innovative systems; (3) Describing and characterizing innovative systems; (4) Assessing innovative systems; (5) Specifying the conditions for the success of innovative systems. The results of the tracking are aimed not only at the farmers, but at their advisors and researchers too: (i) Innovative and effective cropping systems, which can be a source of inspiration for farmers; (ii) Confirmation of the interest of a principle for reasoning cropping systems; (iii) Innovative practices, analyzed within a systemic framework, which can serve as bricks for the design of new systems; (iv) Questions to be looked into more thoroughly by experimentation. Compared to traditional approaches in agronomy, tracking innovative cropping systems provides a double break: break with a top-down approach, where agricultural R & D is regarded as the only source of innovation: by mobilizing the innovative capacities of farmers, tracking increases our collective capacity to invent new practices or new cropping systems, by using not only technical and scientific knowledge, but also the empirical knowledge, that is so rich in agriculture. And break with the primacy given to experimentation, as a source for the production of knowledge and the assessment of innovations. Les agriculteurs sont très inventifs, mais leurs innovations demeurent souvent confinées à leur ferme, ou à de petits réseaux locaux. Et l'intérêt qu'elles pourraient avoir pour des agriculteurs autres que leurs inventeurs est rarement analysé. Le cheminement des innovations à la ferme vise à trouver les innovations techniques ou organisationnelles conçues par des agriculteurs, pour caractériser leur agronomique, économique et la performance environnementale et pour analyser les conditions en lesquelles ces résultats sont exprimés. L'entretien présente les diverses étapes de cette approche de cheminement, appliquées aux systèmes d'emblavage innovateurs, basant sur un grand choix de travaux récents, les Frances, l'Argentin, au Burkina Faso et en Chine : (1) définissant ce que nous recherchons ; (2) identification des systèmes innovateurs ; (3) description et caractérisation des systèmes innovateurs ; (4) l'évaluation des systèmes innovateurs ; (5) spécification des conditions pour le succès des systèmes innovateurs. Les résultats du cheminement sont visés non seulement les agriculteurs, mais leurs conseillers et chercheurs trop : (i) systèmes d'emblavage innovateurs et efficaces, qui peuvent être une source d'inspiration pour des agriculteurs ; (ii) confirmation d'intérêt d'un principe pour les systèmes d'emblavage de motif ; (iii) pratiques innovatrices, analysées dans un cadre systémique, qui peut servir de briques à la conception de nouveaux systèmes ; (iv) questions à regarder dans plus complètement par expérimentation. Comparé aux approches traditionnelles en agronomie, le cheminement des systèmes d'emblavage innovateurs fournit une double coupure : cassez avec une approche hiérarchisée, où la R&D agricole est considérée comme la seule source d'innovation : en mobilisant les capacités innovatrices d'agriculteurs, le cheminement augmente notre capacité collective d'inventer de nouvelles pratiques ou nouveaux systèmes d'emblavage, à l'aide non seulement de technique et de la connaissance scientifique, mais également la connaissance empirique, qui est si riche en agriculture. Et coupure avec la primauté donnée à l'expérimentation, comme source pour la production de la connaissance et de l'évaluation des innovations.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V16242
V16242

Éditeur(s) : HAL CCSD
Résumé : The presence of biological matter (biofilms) in deep geological sites for storage of, for instance, toxic elements or groundwater in aquifers was clearly proved. That biomass triggers physical and chemical processes which greatly modify the durability and the sustainability of the sites. These processes, mainly from oxidative/reductive reactions, are poorly understood. This is mainly due to the fact that former studies were done at the macroscopic level far away from the micrometric scale where relevant processes induced by bacteria take place. Investigations at microscopic level are needed. Thus, we developed an experimental set-up based on the combined use of optical microscopy (transmission), atomic force microscopy (AFM) and electrical and electro-chemical AFM microscopy (EC_AFM) in order to get simultaneous information on topographic and electro-chemical processes. The first highly sensitive step was to use AFM with biological samples in liquid environment: wepresent here a study about AFM imaging of living, moving or self-immobilized bacteria, in their genuine physiological liquid medium and in true in vivo conditions. No external immobilization protocol, neither chemical nor mechanical was needed. For the first time, the native gliding movements of Gram negative Nostoc cyanobacteria upon the surface were studied by AFM. AFM height and mechanical stiffness data were simultaneously acquired. From these, mechanical parameters, inner turgor pressure and Young modulus, were derived for different bacterial species (Anabaenopsis circularis, Rhodococcus wratislaviensis). Our study revealed that AFM imaging is thus possible on moving living species. These results open a large window on new studies of both dynamical phenomena of practical and fundamental interests such as the formation of biofilms and dynamic properties of bacteria in real physiological conditions. The second delicate step was to combine AFM and optical measurements with electrical ones. We mounted a new experimental set-up coupling real-time (i) monitoring of optical properties as the optical density (OD) evolution related to bulk bacterial growth in liquid or as the counting of number of bacteria adhering on the surface of the sample as well and (ii) electrical and electrochemical measurements. Furthermore, these results will shortly be applied to the optimized monitoring of the in-situ activity of bacteria consuming oil pollutants, following this way, in real-time, the bioremediation of an oilcontaminated soil (ANR ECOTECH_BIOPHY program).
La présence de matière biologique (biofilms) dans les sites de stockage géologique profond, d'éléments toxiques ou encore de l'eau potable des aquifères est maintenant clairement démontrée. Cette biomasse est à l'origine de processus physiques et chimiques qui modifient considérablement la durabilité et la pérennité des sites concernés. Ces processus, principalement de type oxydo-réductif, sont encore mal compris. Ceci est principalement dû aux méthodes d'investigation, principalement macroscopiques, loin de l'échelle micrométrique caractéristique des bactéries. Seules des études, basées sur des méthodes d'investigation locale, peuvent apporter les informations requises. Ainsi, nous avons développé un dispositif expérimental basé sur l'utilisation combinée de la microscopie optique (en transmission), la microscopie à force atomique (AFM) et la microscopie AFM en mode électrique et électrochimique (EC_AFM) afin d'obtenir des informations simultanées sur la topographie de l'échantillon et sur les processus électrochimiques à l'échelle des bactéries. La première étape sensible consistait à utiliser l'AFM sur des échantillons biologiques en milieu liquide: nous présentons ici les résultats de l'imagerie AFM en milieu liquide de plusieurs types de bactéries dans leurs conditions physiologiques naturelles (conditions in vivo). Aucun protocole d'immobilisation, ni chimique ni mécanique, n'a été nécessaire; et pour la première fois, les mouvements de reptation de cyanobactéries Nostoc ont été étudiés par l'AFM. Les études AFM ont permis d'acquérir des données topographiques mais aussi mécaniques : nous avons pu ainsi mesurer le module d'Young, la pression de turgescence de différentes souches bactériennes (Anabaenopsis circularis, Rhodococcus wratislaviensis). Cette étude complète, a révélé que l'imagerie AFM est donc possible sur des espèces vivantes en mouvement. Ces résultats ouvrent une grande fenêtre sur de nouvelles études d'intérêts tels que la formation de biofilms et les propriétés dynamiques de bactéries dans des conditions physiologiques réelles. La deuxième étape délicate était de combiner l'AFM aux mesures optiques et électriques. Nous avons développé un nouveau dispositif expérimental permettant (i) le suivi de l'évolution de la croissance bactérienne par la mesure des propriétés optiques comme la densité optique DO (pour le développement bactérien en volume - milieu planctonique) , ou l'analyse de l'image du substrat par comptage du nombre de bactéries sur la surface de l'échantillon (biofilm), et (ii) les mesures électriques et électrochimiques. L'ensemble de ces résultats sera prochainement appliqué au développement de nouveaux outils de surveillance d'une biodépollution de terrain contaminé par les hydrocarbures, par le suivi in situ et en temps réel de l'activité de bactéries dépolluantes (ECOTECH_BIOPHY ANR).
https://tel.archives-ouvertes.fr/tel-01044714

tel-01044714
https://tel.archives-ouvertes.fr/tel-01044714
https://tel.archives-ouvertes.fr/tel-01044714/document
https://tel.archives-ouvertes.fr/tel-01044714/file/theseDhahri2013.pdf

Éditeur(s) : HAL CCSD
Résumé : This thesis falls within the scope of social and human geography and more exactly of« disability studies ». Understanding the disability like a « social object », the thesis analyzes the societal consideration of disabled people in non-urbanized areas with a high issue of touristic, recreational and patrimonial development. In the first place, it's the recent construction of disability as a social object that is discussed by reminding the history of the societal consideration of the disabled person in our occidental world. The French model and his fundamental rule of global accessibility for ail the domains of the social life are explained and the « Nature and Disability » thematic is more precisely analyzed as a development of an active living ideal for people who are in a disability situation. Secondly, the thesis develops this thematic on the particular field of the Reunion Island and tries to answer to a question which is both simple and complicated: « Today, how we live with a disability on the Reunion Island? ». ln a last time and on the basis of this study of the disability inside a Reunion Island society with accelerated transformations, the thesis specifies the current tendencies with the emergence of new public policies for the welcome of disabled people on natural and touristic areas of the island. To conclude and referring to an original survey, the thesis suggests some tools of evaluation and decision-making aids to these areas.
Cette thèse s'inscrit dans le champ de la géographie humaine et sociale et plus précisément dans celui des « disability studies ». En positionnant le handicap comme une « figure du social », la thèse analyse la prise en compte sociétale des personnes à mobilité réduite (PMR) dans des environnements non urbanisés, à très fort enjeu de développement touristique, récréatif et patrimonial. Dans un premier temps, c'est la construction récente du handicap en tant que figure du social qui est abordée, en rappelant l'historique de la considération de la personne handicapée dans nos sociétés occidentales. Le modèle français et son principe fondamental d'accessibilité généralisée à tous les domaines de la vie sociale sont détaillés et la thématique « Nature et Handicap » est analysée plus précisément, en tant que développement d'un idéal de vie active pour les personnes en situation de handicap. Dans un second temps, la thèse développe cette thématique sur le terrain particulier de l'Île de La Réunion et tente de répondre à une question à la fois simple et complexe : « comment vit-on avec une déficience aujourd'hui à La Réunion ? ». Dans un dernier temps et sur la base de cette analyse du handicap au sein d'une société réunionnaise aux mutations accélérées, la thèse précise les tendances actuelles avec l'apparition de nouvelles politiques publiques d'accueil des PMR dans les espaces naturels et touristiques de l'île. S'appuyant sur une enquête originale, la thèse propose enfin des outils d'évaluation et d'aide à la décision spécifiques à ces espaces.
https://tel.archives-ouvertes.fr/tel-01279042

NNT : 2012LARE0025
tel-01279042
https://tel.archives-ouvertes.fr/tel-01279042
https://tel.archives-ouvertes.fr/tel-01279042/document
https://tel.archives-ouvertes.fr/tel-01279042/file/2012lare0025_AGuenat.pdf

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The diffusion of titanium along with Ni, Co and Mn in pure synthetic forsterite has been studied as a function of temperature, oxygen fugacity, crystallographic orientation and chemical potentials in the four-component system MgO–SiO2–TiO2–TiO1·5. In over 100 different experimental conditions, no Ti diffusion profiles with the classical shape of the error function were observed. Instead, the profiles vary between ‘stepped’ at high fO2 (probably owing to diffusion on octahedral sites and trapping in tetrahedral sites), to hockey-stick shapes at low fO2 owing to concentration-dependent diffusion. The profile shapes vary systematically between these end-members according to oxygen fugacity. These profile shapes are also reproduced in experiments using natural San Carlos olivine. The change in profile shape is interpreted to be a function of valence-state change from Ti4+ to Ti3+, shown by a sigmoidal log fO2–diffusivity relationship. To distinguish between Ti4+ and Ti3+ in forsterite, a diffusion profile was also investigated using ‘hydroxylation spectroscopy’ whereby a crystal from a diffusion experiment was hydroxylated by annealing in an H2O-rich fluid at moderate pressure and temperature. The point defects associated with the added structural OH were then determined by infrared spectroscopy, providing evidence for the presence of Ti4+ and Ti3+ at intermediate oxygen fugacity. The transition from Ti4+ to Ti3+ occurs at considerably higher fO2 in these diffusion experiments than in equilibrium experiments in similar systems. Titanium diffusion, qualified using a mobility parameter (M), is fastest along the c-axis, at high activity of silica, low oxygen fugacity and high temperature. The rate of Ti diffusion is broadly similar to those of Mn, Ni and Co, and closer to published rates of Mg self-diffusion in olivine than Si self-diffusion. The observed Ti3+ and Ti4+ diffusion occurs on the M-sites. From statistical examination of the large Mn, Ni and Co diffusivity dataset, we determine that there is a 102/3 dependence of diffusion on aSiO2; the cations diffuse more rapidly at high aSiO2. In addition, diffusivity has a 10–1/8 dependence on fO2, suggested to be the result of increased concentration of loosely bound Ti3+–vacancy pairs, which enhance the mobility of other cations. This behaviour is likely to be present in natural systems where trivalent (e.g. Fe3+, Al3+, Cr3+) and divalent cations diffuse together. Consideration should be given to diffusive interference by highly charged, fast-moving cations when extracting time scales from frozen diffusion profiles.
ISSN: 0022-3530

hal-01531344
https://hal.archives-ouvertes.fr/hal-01531344
DOI : 10.1093/petrology/egw067

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Homosexuality stands at the center of the last two centuries’ struggle to understand human sexuality; the HIV epidemic among gay men has cemented that in place. And the era of HIV/AIDS finally brought the inherent uncertainties and conflicts in our understanding of human sexuality to the surface and opened the way to re-think sex, identity, and sexual health. I discuss these re-conceptualizations, providing a way around the analytic dichotomies by embracing our embodiment in ecological contexts. In concluding, I suggest how to get out of our “heads” where linguistic binaries dominate our thinking with the superior/inferior evaluations endemic to self-other comparisons. Through our thick, sensuous experience, we can live in the present moment as one embodied person among other interconnected bodies without psychological games of one-up and one-down.
L’homosexualité se trouve au centre de la mobilisation pour comprendre la sexualité humaine, vieille maintenant de deux siècles. L’épidémie du SIDA a endurci cette mobilisation et a remis sur le devant de la scène les incertitudes et les conflits qui entourent notre approche de la sexualité humaine, offrant une nouvelle manière de penser la sexualité, l’identité et la santé sexuelle. J’analyse cette re-conceptualisation dans un contexte écologique qui contourne les dichotomies analytiques. En conclusion, je suggère une manière de nous libérer des binarismes linguistiques qui nous emprisonnent dans le besoin endémique de s’évaluer par rapport aux autres en termes de supériorité et d’infériorité. En reconnaissant la signifiance de notre expérience sensuelle, nous pouvons vivre le moment présent et établir des connexions avec les autres sans sombrer mentalement dans un rapport de supériorité ou d’infériorité.

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5922
http://journals.openedition.org/etudescaribeennes/5922