Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The Oman ophiolite is regarded as derived from a fast spreading oceanic ridge. As in its present-day marine analogs, expectedly, the gabbro unit crystallized in a large magma chamber underneath a small melt lens. In ophiolites, this melt lens is reduced to a horizon mapped in the field, where the floor and the roof of the melt lens joined. The magmatic activity of the former melt lens has been studied in gabbros located below the melt lens horizon. Beneath a stable melt lens, gabbros subside and drift through the steep walls of the magma chamber as steeply foliated gabbros. In contrast, in unstable melt lenses more specifically considered here, flat-lying gabbros are exposed beneath the lens. These gabbros were settling on the floor while the melt lens was retreating. Their strong magmatic foliations and lineations point to a dynamic deposition on the floor, and lineation trends record the structure of convection rolls within the lens. Time constraints suggest a similar to 100 year periodicity of melt recharge by short and powerful melt pulses followed by a shorter time of convection activity after recharge and a longer period of static magma settling, as recently proposed for the East Pacific Rise. At each new melt pulse, the lens nearly doubles its volume by surface expansion, within a short time lapse, before slowly and progressively retreating to feed crustal accretion. Large horizontal surface inflation of the lens better explains the seawater hydration of the accreting crust than melt lens vertical motion through the lid.
ISSN: 0148-0227

hal-00617452
https://hal.archives-ouvertes.fr/hal-00617452
DOI : 10.1029/2010JB007934

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The growth of relief in active tectonic areas is mainly controlled by the interactions between tectonics and surface processes (erosion and sedimentation). The study of long-lived morphologic markers formed by these interactions can help in quantifying the competing effects of tectonics, erosion and sedimentation. In regions experiencing active extension, river-long profiles and faceted spurs (triangular facets) can help in un- derstanding the development of mountainous topography along normal fault scarps. In this study, we devel- oped analogue experiments that simulate the morphologic evolution of a mountain range bounded by a normal fault. This paper focuses on the effect of the fault slip rate on the morphologic evolution of the foot- wall by performing three analogue experiments with different fault slip rates under a constant rainfall rate. A morphometric analysis of the modelled catchments allows comparing with a natural case (Tunka half- graben, Siberia). After a certain amount of fault slip, the modelled footwall topographies of our models reaches a dynamic equilibrium (i.e., erosion balances tectonic uplift relative to the base level) close to the fault, whereas the topography farther from the fault is still being dissected due to regressive erosion. We show that the rates of vertical erosion in the area where dynamic equilibrium is reached and the rate of re- gressive erosion are linearly correlated with the fault throw rate. Facet morphology seems to depend on the fault slip rate except for the fastest experiment where faceted spurs are degraded due to mass wasting. A stream-power law is computed for the area wherein rivers reach a topographic equilibrium. We show that the erosional capacity of the system depends on the fault slip rate. Finally, our results demonstrate the pos- sibility of preserving convex river-long profiles on the long-term under steady external (tectonic uplift and rainfall) conditions.
ISSN: 0040-1951

hal-00646966
https://hal.archives-ouvertes.fr/hal-00646966
https://hal.archives-ouvertes.fr/hal-00646966/document
https://hal.archives-ouvertes.fr/hal-00646966/file/preprint_Strak_2011.pdf
DOI : 10.1016/j.tecto.2011.10.005

Éditeur(s) : HAL CCSD Institute of Electrical and Electronics Engineers
Résumé : International audience
The state-space modeling of partially observed dynamical systems generally requires estimates of unknown parameters. The dynamic state vector together with the static parameter vector can be considered as an augmented state vector. Classical filtering methods, such as the extended Kalman filter (EKF) and the bootstrap particle filter (PF), fail to estimate the augmented state vector. For these classical filters to handle the augmented state vector, a dynamic noise term should be artificially added to the parameter components or to the deterministic component of the dynamical system. However, this approach degrades the estimation performance of the filters. We propose a variant of the PF based on convolution kernel approximation techniques. This approach is tested on a simulated case study.
ISSN: 0018-9251

inria-00459886
https://hal.inria.fr/inria-00459886
DOI : 10.1109/TAES.2009.5259183

Éditeur(s) : HAL CCSD Wiley
Résumé : The allocation and cycling of carbon (C) within forests is an important component of the biospheric C cycle, but is particularly understudied within tropical forests. We synthesise reported and unpublished results from three lowland rainforest sites in Amazonia (in the regions of Manaus, Tapajos and Caxiuana), all major sites of the Large-Scale Biosphere-Atmosphere Programme (LBA). We attempt a comprehensive synthesis of the C stocks, nutrient status and, particularly, the allocation and internal C dynamics of all three sites. The calculated net primary productivities (NPP) are 10.1 +/- 1.4 Mg C ha(-1) yr(-1) (Manaus), 14.4 +/- 1.3 Mg C ha(-1) yr(-1) (Tapajos) and 10.0 +/- 1.2 Mg C ha(-1) yr(-1) (Caxiuana). All errors bars report standard errors. Soil and leaf nutrient analyses indicate that Tapajos has significantly more plant-available phosphorus and calcium. Autotrophic respiration at all three sites (14.9-21.4 Mg C ha yr(-1)) is more challenging to measure, with the largest component and greatest source of uncertainty being leaf dark respiration. Comparison of measured soil respiration with that predicted from C cycling measurements provides an independent constraint. It shows general good agreement at all three sites, with perhaps some evidence for measured soil respiration being less than expected. Twenty to thirty percent of fixed C is allocated belowground. Comparison of gross primary productivity (GPP), derived from ecosystem flux measurements with that derived from component studies (NPP plus autotrophic respiration) provides an additional crosscheck. The two approaches are in good agreement, giving increased confidence in both approaches to estimating GPP. The ecosystem carbon-use efficiency (CUEs), the ratio of NPP to GPP, is similar at Manaus (0.34 +/- 0.10) and Caxiuana (0.32 +/- 0.07), but may be higher at Tapajos (0.49 +/- 0.16), although the difference is not significant. Old growth or infertile tropical forests may have low CUE compared with recently disturbed and/or fertile forests.
ISSN: 1354-1013

hal-01032150
https://hal.archives-ouvertes.fr/hal-01032150
DOI : 10.1111/j.1365-2486.2008.01780.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Despite the increasing dominance of turf algae in coral reefs, few studies have investigated their physiological and ecological responses to changes in abiotic factors. We tested the effects of depth and ultraviolet radiation on turf algae at different levels of successional stages using two experiments. Depth-related differences were found for all turf algal communities, characterized by a higher amount of the cyanobacteria taxon Dichothrix and the red filamentous genera Poly-/Herposiphonia in the shallow and the appearance of oscillating cyanobacteria in deeper waters. In the first experiment, cross-depth transplantation of 153 days old communities influenced percentage cover, biomass and taxa composition. Downward transplantation lowered overall biomass and abundance of the foraminifera Sorites, whereas the crustose green alga Pringsheimiella and filamentous cyanobacteria colonized the communities. A nearly reverse pattern was observed in upward transplanted communities. Overall we distinguished between sensitive taxa, like Oscillatoria, and taxa able to acclimate to alterations in their environment, like Pringsheimiella, Poly/Herposiphonia and Dichothrix. In the second experiment, algae grown for 285 days at 5 m were exposed together with a set of sterile settlement tiles to three UVR regimes at 2 m for 22 days. UVR had no effect on turf algal communities regardless of successional stage. This study highlights the presence of high light and UV tolerant species. The high UV tolerance of turf communities may confer a competitive advantage over other more sensitive coral reef biota, such as corals. This study demonstrates that turf algae are dynamic communities exhibiting species-specific resistance to environmental changes.
ISSN: 0022-0981

hal-01333486
https://hal-univ-perp.archives-ouvertes.fr/hal-01333486
DOI : 10.1016/j.jembe.2014.07.017

Éditeur(s) : HAL CCSD Wiley
Résumé : Tank bromeliads form a conspicuous, yet neglected freshwater habitat in Neotropical forests. Recent studies driven by interests in medical entomology, fundamental aspects of bromeliad ecology and experimental research on food webs have, however, prompted increasing interest in bromeliad aquatic ecosystems. As yet, there is nothing in the literature about the life histories and environmental drivers of invertebrate population dynamics in tank bromeliads. Based on fortnightly samples taken over oneyear, size frequency plots and individual dry masses allowed us to establish the life cycles and growth rates of the dominant aquatic invertebrates in a common bromeliad species of French Guiana. Linear mixed-effect models and Mantel tests were used to predict changes in density, biomass, and growth rates in relation to temperature, rainfall, humidity and detrital resources. Annual variations in invertebrate densities and biomasses could be described according to three types of distribution: unimodal, bimodal or almost constant. Despite seasonal variations, precipitation, temperature, relative humidity and detritus concentration accounted significantly for changes in density and biomass, but we found no significant responses in growth rates of most invertebrate species. Species rather displayed non-seasonal life cycles with overlapping cohorts throughout the year. There was also a trend for delayed abundance peaks among congeneric species sharing similar functional traits, suggesting temporal partitioning of available resources. Beyond novel knowledge, quantitative information on life histories is important to predict food-web dynamics under the influence of external forcing and self-organisation. Our results suggest that changes in species distribution that will affect population dynamics through biotic interactions in space and/or time could have greater effects on food webs and ecosystem functioning than changes in environmental factors per se.
ISSN: 0046-5070

hal-01607779
https://hal.archives-ouvertes.fr/hal-01607779
DOI : 10.1111/fwb.12862
PRODINRA : 407311

Résumé : Preliminary analysis of the impact of an environmental change on ichtyologic fauna marinates and fishing in Guyanese water enter within the framework of the program CHALOUPE (dynamic Change of the exploited marine biodiversity and the viability of the Fisheries) coordinated by Ifremer Cayenne and financed by the ANR (National Agency of Research). The study focuses on: -analysis temporal variations of various environmental parameters (sea surface temperature and salinity, the phenomenon El Niño) -fish physical characteristics (tolerances of temperature and salinity, maximum height, distribution…) - analysis of the unloadings per unit of effort of the inshore fishing and an economic analysis of the selling price of fish Data are found on data bases and are given by scientists. The statistical studies and the cartographic representations show that there is an increase in temperature of water in Guiana since the end of the Nineties. The model AquaMaps® simulates the potential consequences of this reheating on the fish distribution. Certain stocks of fishing are weakened. For the moment, if the composition of the captures of inshore fishing changes, that seems more due to a change of fishing strategy than due to an impact of the climatic change. In addition, the average value of the capture increased for reason commercial.
Les analyses de l’impact d’un changement environnemental sur la faune ichtyologique marine et la pêche dans les eaux guyanaises entrent dans le cadre du programme CHALOUPE (CHAngement gLObal, dynamiqUe de la biodiversité marine exploitée et de la viabilité des Pêcheries) coordonné par l’Ifremer Cayenne et financé par l’ANR (Agence Nationale de la Recherche). L’étude porte sur : -l’analyse des variations temporelles de différents paramètres environnementaux (température et salinité de surface des eaux, le phénomène El Niño) à l’échelle de quelques décennies -les caractéristiques physiques des poissons (tolérances de températures et de salinité (taille maximum, répartition…) ; -l’analyse des débarquements par unité d’effort de la pêche côtière depuis les années 70 ; -une analyse économique de la pêche ; Les données sont récoltées à partir de bases de données et au près de différents chercheurs. Les études statistiques et les représentations cartographiques démontrent qu’il y a bien une augmentation de température des eaux en Guyane depuis la fin des années 90. Le modèle statistique sous AquaMaps® permet de simuler les conséquences potentielles de ce réchauffement sur la répartition des poissons. Dans un tel contexte, certains stocks de pêche sont fragilisés. Pour le moment, si la composition des captures de la pêche côtière se modifie dans le même temps, cela semble plus du fait de changement de stratégie de pêche que du fait de l’impact du changement climatique. Par ailleurs, la valeur moyenne de la capture a augmenté pour des raisons commerciales.

Droits : 2006 Ifremer
http://archimer.ifremer.fr/doc/00077/18855/16429.pdf
http://archimer.ifremer.fr/doc/00077/18855/

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : The mechanical equilibrium of an orogenic wedge is maintained thanks to interactions between tectonic processes and surface processes. To better constrain the influence of erosion and sedimentation on the evolution of orogens, we performed a series of analogue models based on the tapered wedge principle, varying the amounts of erosion and sedimentation. The models develop by frontal accretion in the foreland basin and by simple underthrusting and subsequent underplating in the hinterland. The variations in rates of erosion and sedimentation strongly modify the extent, the morphology, the structures, the timing of development and the material paths in the different models. Under certain conditions, entire structural units can be formed and subsequently eroded out of the geological record, leading to important underestimations when restoring sections. Particles located in the converging lower-plate or in the upper-plate show complex uplift paths related to tectonic stages. The correlation between models and three Alpine tectonic cross-sections emphasizes the role of erosion and sedimentation on the dynamics and development of the orogen and adjacent Molasse basin. Along strike changes in the present structure of the orogen could be explained in part by differences in surface processes.
EISSN: 1777-5817

hal-00411140
https://hal.archives-ouvertes.fr/hal-00411140
DOI : 10.2113/gssgfbull.3.297

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Heterogeneous patterns of malaria transmission are thought to be driven by factors including host genetics, distance to mosquito breeding sites, housing construction, and socio-behavioural characteristics. Evaluation of local transmission epidemiology to characterize malaria risk is essential for planning malaria control and elimination programmes. The use of geographical information systems (GIS) techniques has been a major asset to this approach. To assess time and space distribution of malaria disease in Bandiagara, Mali, within a transmission season, data were used from an ongoing malaria incidence study that enrolled 300 participants aged under six years old ". Methods: Children's households were georeferenced using a handheld global position system. Clinical malaria was defined as a positive blood slide for Plasmodium falciparum asexual stages associated with at least one of the following signs: headache, body aches, fever, chills and weakness. Daily rainfall was measured at the local weather station. Landscape features of Bandiagara were obtained from satellite images and field survey. QGIS™ software was used to map malaria cases, affected and non-affected children, and the number of malaria episodes per child in each block of Bandiagara. Clusters of high or low risk were identified under SaTScan W software according to a Bernoulli model. Results: From June 2009 to May 2010, 296 clinical malaria cases were recorded. Though clearly temporally related to the rains, Plasmodium falciparum occurrence persisted late in the dry season. Two " hot spots " of malaria transmission also found, notably along the Yamé River, characterized by higher than expected numbers of malaria cases, and high numbers of clinical episodes per child. Conversely, the northeastern sector of the town had fewer cases despite its proximity to a large body of standing water which was mosquito habitat. Conclusion: These results confirm the existence of a marked spatial heterogeneity of malaria transmission in Bandiagara, providing support for implementation of targeted interventions. Background Malaria is one of the leading causes of morbidity and mortality in the world, with an estimated 3.3 billion people at risk of malaria [1]. The incidence of malaria worldwide is estimated to be 216 million cases per year, with 81% of these cases occurring in sub-Saharan Africa. Malaria kills approximately 655,000 people per year; 91% of deaths occur in sub-Saharan Africa [1], mostly in children under five years of age. In Mali, West Africa, malaria represents 36.5% of consultation motives in health center, it is a leading cause of morbidity and mortality children of less than five years of age and the first reason of anaemia in pregnant women [2]. Malaria transmission is seasonal. Malaria parasite transmission and clinical disease are characterized by important microgeographic variation, often between adjacent villages, households or families [3-8]. This local heterogeneity is driven by a variety of factors including human genetics [9,10], distance to potential breeding sites [11,12], housing construction
ISSN: 1475-2875

hal-01307672
https://hal-amu.archives-ouvertes.fr/hal-01307672
https://hal-amu.archives-ouvertes.fr/hal-01307672/document
https://hal-amu.archives-ouvertes.fr/hal-01307672/file/1475-2875-12-82.pdf
DOI : 10.1186/1476-072X-2-5

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Au cours des vingt dernières années, l'industrie des croisières au Mexique a apporté des changements importants qui découlent des tendances mondiales actuelles, d'un meilleur positionnement sur le marché, pour l'adoption généralisée de politiques nationales de promotion du tourisme croisière et pour la réforme radicale du système portuaire national qui a permis l'entrée de la participation privée dans les investissements des infrastructures, de gestion et d'exploitation des ports. Dans ce contexte, on a redéfini l´organisation spatiale du tourisme de croisière avec de nouveaux ports d´arrivée, des itinéraires variés à partir de différents ports d´origine et d’escales plaçant le Mexique en tête des destinations mondiales de l’industrie des croisières. Ainsi, l'objectif de cet article est d'examiner les conditions qui ont conduit à la dynamique spatio-temporelle du tourisme de croisière dans le pays à travers un examen critique de la nouvelle géographie régionale du tourisme de croisière au Mexique.
The cruise industry in Mexico has had significant changes stemming from current global trends during the last two decades. This has been due to its favorable and strategic geographical position in the market, its warm climate and proximity to the United States. Hence there has been a major relevance towards adopting national tourism policies as well as reforming the national port system allowing the entrance of private investment infrastructure, cruise terminal management and operation. The spatial organization of cruise tourism destination ports in Mexico has been redefined in this context. That is to say, there are new home ports, new routes and ports of call that have placed the country as a world’s leading destination for cruise ship arrivals. Therefore, the aim of this paper is to examine the conditions which have led the spatio-temporal dynamics into a critical review of the new regional geography of cruise tourism in Mexico.
En las dos últimas décadas el sector de los cruceros turísticos en México ha presentado profundos cambios, derivados de las tendencias globales, de un mayor aprovechamiento de su favorable condición geográfica dentro del mercado, por una mayor incorporación de la actividad en las políticas turísticas nacionales y por la profunda reforma del sistema portuario nacional que posibilitó el ingreso de la participación privada en la inversión de infraestructura, gestión y operación de terminales de cruceros. En este contexto se ha redefinido la organización espacial del turismo de cruceros con nuevas rutas que articulan diferentes puertos de origen y escalas que han posicionado a México como destino líder mundial en arribo de cruceros. De esta forma, el objetivo del presente artículo es examinar las condiciones que han propiciado la dinámica espacio-temporal del turismo de cruceros en el país, que conduzca a una revisión crítica de la nueva geografía regional de los cruceros turísticos en México.
Mexique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5077
http://journals.openedition.org/etudescaribeennes/5077

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Après avoir rappelé que comme concept de gestion des territoires, le développement durable peut s’inscrire dans un système territorial complexe, l’article s’interroge sur les imaginaires associés à la ruralité et à l’insularité. Largement issue du regard de nos sociétés urbaines, la critique des abus d’un modèle de développement insulaire peu respectueux d’un environnement détérioré et/ou à l’abandon, conduit à promouvoir une gestion des territoires intégrant également une dimension économique et socioculturelle, notamment un fort mouvement de « patrimonialisation », sorte de réinvention de l’île mythique, symbole d’un équilibre passé. Divers exemples (île grecque de Skopelos, Corse, Martinique) montrent que ressources et savoir-faire spécifiques, difficilement transposables en dehors du contexte insulaire, peuvent être considérés comme un atout pour le développement ; ils renforcent l’identité d’une communauté et inspirent des dynamiques sociales renouvelées. Pour autant, il importe de réfléchir aux interactions entre des filières qui partagent les mêmes lieux, les mêmes ressources et impliquent les mêmes personnes. À l’évidence, la qualité du lien social augmente la résilience du système territorial même si cela passe par une redéfinition des règles collectives qui visent à inventer des solidarités durables passant davantage par des savoir-être ensemble que par des savoir-faire purement techniques.
As a concept of territorial management, sustainable development can be analysed in the systemic vision allowed by complex territorial systems. This article wonders about the representations associated to rural areas and insularity. Largely encouraged by our modern societies, the critical vision of island development – not environmentally friendly models – promotes an integrated vision of development aiming at combining economical and sociocultural considerations. The great movement of cultural heritage, sort of reinvention of mythic islands symbolising a past equilibrium is then progressively supported. Different examples dealt with in this article (The Greek island of Skopelos, Corsica, Martinique) show that resources and specific know-how, not easily transferable out of the insular context, can be considered as strong advantages for development. They reinforce communities’ identity and favour new social dynamics. Obviously, quality ties increase the resilience of the territorial system even though it necessitates to redefine collective rules that aim at inventing sustainable solidarity relying mainly on knowing how to behave instead of pure technical know-how.
Grèce
Corse
Martinique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.3454
http://journals.openedition.org/etudescaribeennes/3454

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: The effects of pressure-controlled (PC) ventilation on the ventilatory and haemodynamic parameters during laparoscopy procedures had not been carefully assessed. This prospective cross-over study was undertaken to compare how volume-controlled (VC) and PC modes could affect pulmonary mechanics, gas exchange, and cardiac function in patients undergoing laparoscopy. METHODS: Twenty-one patients undergoing laparoscopic urological procedures had their lungs ventilated at the beginning with VC ventilation. PC ventilation was instituted at the end of the VC sequence. Ventilator settings were adjusted to keep tidal volume, respiratory rate, and Fi(o(2)) constant in every mode. A complete set of ventilatory, haemodynamic, and gas exchange parameters was obtained under VC after 40 min of pneumoperitoneum and 20 min after switching for PC. Transoesophageal echocardiography was performed in order to evaluate systolic and diastolic function of the heart. RESULTS: When VC was switched to PC, peak airway pressure decreased [mean (sd) 32 (6) vs 27 (6) cm H(2)O; P < 0.0001], peak inspiratory flow increased [17 (3) vs 48 (8) litre min(-1); P < 0.0001), and dynamic compliance improved [+15 (8)%]. No difference was noted for static airway pressure, static compliance, and arterial oxygenation. No significant change could be demonstrated in the systolic [left ventricular end-systolic wall stress 66 (16) vs 63 (14) x 10(3) dyn cm(-2) m(-2)] or diastolic function [early diastolic velocity 10.3 (2.5) vs 10.5 (2.7) cm s(-1)]. CONCLUSIONS: In this study, no short-term beneficial effect of PC ventilation could be demonstrated over conventional VC ventilation in patients with pneumoperitoneum.
BJA

hal-00689758
https://hal.archives-ouvertes.fr/hal-00689758
DOI : 10.1093/bja/aem166
PUBMED : 17626027

Éditeur(s) : HAL CCSD
Résumé : The social change which takes place in the French West Indies after the Second World War ensues from a historical interactive process. It occurs between 1946 and 1961, within the frame of the new dynamic fostered in the aftermath of the war. Here we refer to the new political status of Department, the outbreak of social conflicts during the process of decolonization, the public policies and the planning of “the economic and social development” of the overseas departments. The dynamic also includes the population growth with the birth of a new generation- from the sociological point of view. The aforementioned interaction instils the new type of society emerging in the French West Indies since the 1960’s, without drastically changing their colonial social structure. This transformation named “Departmentalization” seems paradoxical because it will generate “modern” social frustrations, while maintaining existing frustrations that stemmed from the plantation society. This process led to the transition from a slave society to a consumer society. It allows us to understand the persistence of a latent social unrest in these departments, in spite of the overall significant improvement of the living conditions during the early twentieth century.
La transformation sociale des Antilles françaises qui se produit après la Seconde Guerre mondiale résulte d’un processus interactif historique. Celui-ci se produit entre 1946 et 1961 autour des nouvelles dynamiques de l’après-guerre. Il s’agit du statut départemental, de la décolonisation avec l’explosion des conflits sociaux, de la politique publique de « développement économique et social » avec la planification dans les départements d’outre-mer, et de l’accroissement démographique avec l’apparition d’une nouvelle génération « sociologique ». C’est précisément cette interaction qui est à l’origine du nouveau type de société qui émerge aux Antilles à partir des années 1960 sans pour autant que leur structure sociale coloniale ne soit bouleversée. Cette construction qui prend le nom commun de « Départementalisation » est paradoxale car elle va générer des frustrations sociales « modernes », tout en maintenant des frustrations anciennes issues de la société de plantation. En induisant ainsi le passage d’un monde d’ « habitation » à un monde de consommation, cette construction permet de comprendre un peu mieux, le maintien, au début du XXIe siècle, d’un malaise social latent dans ces départements en dépit d’une amélioration sensible et générale des conditions de vie.
https://hal.archives-ouvertes.fr/tel-01675708

Droits : info:eu-repo/semantics/OpenAccess
tel-01675708
https://hal.archives-ouvertes.fr/tel-01675708
https://hal.archives-ouvertes.fr/tel-01675708/document
https://hal.archives-ouvertes.fr/tel-01675708/file/D%C3%A9colonisation%20et%20changement%20social%20aux%20Antilles%20fran%C3%A7aises%20%281946-1961%29%20-%20Ma%C3%ABl%20LAVENAIRE%202017.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In this paper, we present an original and formal framework, the D2SNet model designed to combine both the social network evolution and the diffusion dynamics among individuals. We have conducted experiments on three social networks that show identical characteristics as real social networks. A formal definition of the model is provided and we describe its implementation in a simulation tool. We represent human behaviors and information dissemination strategies by standard and synthetic scheme. In a first step, we study the impact of network growing strategies only and we highlight important parameters such as the evolution speed and mainly the kind of strategies that favour or not the spread. Then we study a more complete evolution strategy that involves link creation and deletion. We provide a deep analysis on the impact of each parameter such as evolution speed, creation and deletion probabilities and dynamic human behaviors on the diffusion amplitude and coverage. Our study gives a novel and useful insight in the diffusion process in a dynamic context.
ISSN: 0747-5632

hal-00786164
https://hal.archives-ouvertes.fr/hal-00786164
DOI : 10.1016/j.chb.2012.06.004

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
DNase I requires Ca²+ and Mg²+ for hydrolyzing double-stranded DNA. However, the number and the location of DNase I ion-binding sites remain unclear, as well as the role of these counter-ions. Using molecular dynamics simulations, we show that bovine pancreatic (bp) DNase I contains four ion-binding pockets. Two of them strongly bind Ca²+ while the other two sites coordinate Mg²+. These theoretical results are strongly supported by revisiting crystallographic structures that contain bpDNase I. One Ca²+ stabilizes the functional DNase I structure. The presence of Mg²+ in close vicinity to the catalytic pocket of bpDNase I reinforces the idea of a cation-assisted hydrolytic mechanism. Importantly, Poisson-Boltzmann-type electrostatic potential calculations demonstrate that the divalent cations collectively control the electrostatic fit between bpDNase I and DNA. These results improve our understanding of the essential role of cations in the biological function of bpDNase I. The high degree of conservation of the amino acids involved in the identified cation-binding sites across DNase I and DNase I-like proteins from various species suggests that our findings generally apply to all DNase I-DNA interactions.
ISSN: 1553-734X

hal-00645165
https://hal.archives-ouvertes.fr/hal-00645165
https://hal.archives-ouvertes.fr/hal-00645165/document
https://hal.archives-ouvertes.fr/hal-00645165/file/journal.pcbi.1001000.pdf
DOI : 10.1371/journal.pcbi.1001000

Résumé : The MEDECO Leg 2 cruise followed the MEDECO Leg 1 cruise that had crossed the Mediterranean Sea from the west to the east to study benthic communities of the Var canyon, deep corals found on the Calabrian Margin and cold seep ecosystems of the Mediterranean Ridge. The main objective of the MEDECO Leg 2 cruise was to study and compare, using a multidisciplinary approach, the structure and dynamics of deep-sea ecosystems at various active cold seep sites from the Nile deep sea fan and the Calabrian Arc, in the Eastern Mediterranean sea. During MEDECO Legs 1 & 2, a multiscale strategy was promoted to integrate (1) a high resolution cartography of geological structures (km2 scale), (2) a detailed mapping, including video imagery, of smaller-scale areas (scale 100 to 300 m2), (3) the physical, chemical and sedimentary characteristics of the habitat (multiscale), (4) the structure and functioning of faunal communities, including microbes, in terms of composition, diversity and biomass (multiscale), (5) small scale studies of interactions between organisms and their environment (scale < m2), (6) detailed ecophysiological studies at the organism scale on invertebrates. The use of the ROV “Victor 6000” and of various equipments for in situ and ex situ observations and measurements has helped reaching our objectives. The MEDECO cruise represented the key-Mediterranean cruise of the HERMES project “Hotspot Ecosystem Research on the Margins of European Seas” (P.I. P. Weaver, NOC-Southampton). The cruise was organized to follow the objectives of the HERMES program to better understand the functioning of deep ecosystems of the continental margins aiming at obtaining: (1) the description and quantification of the natural drivers (geological, hydrological, chemical factors) that control the distribution of ecosystems on margins; (2) the characterization and quantification of biodiversity, from bacteria to megafauna, as well as the knowledge of ecosystem functioning; (3) the study of ecosystems dynamics including the biology/physiology of key-species. Specific objectives. Colonization experiments conducted in the frame of two European programs, Diwoo and Chemeco, have given the opportunity to recover the fauna installed in the devices deployed during the Bionil cruise (2006) and to deploy new ones at the same site located in the pockmark area of the central province of Nile deep sea fan.

Droits : 2008 Insu, Cnrs, Locean
http://archimer.ifremer.fr/doc/00134/24550/22583.pdf
http://archimer.ifremer.fr/doc/00134/24550/

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Nucleation mechanisms occurring during dynamic recrystallization play a crucial role in the evolution of microstructures and textures during high temperature deformation. In polycrystalline ice, the strong viscoplastic anisotropy induces high strain heterogeneities between grains which control the recrystallization mechanisms. Here, we study the nucleation mechanisms occurring during creep tests performed on polycrystalline columnar ice at high temperature and stress (T=−5°C;σ=0.5 MPa) by post-mortem analyses of deformation microstructures using cryogenic electron backscatter diffraction. The columnar geometry of the samples enables discrimination of the nuclei from the initial grains. Various nucleation mechanisms are deduced from the analysis of the nuclei relations with the dislocation sub-structures within grains and at grain boundaries. Tilt sub-grain boundaries and kink bands are the main structures responsible for development of polygonization and mosaic sub-structures. Nucleation by bulging at serrated grain boundaries is also an efficient nucleation mechanism near the grain boundaries where strain incompatibilities are high. Observation of nuclei with orientations not related to the ‘parent’ ones suggests the possibility of ‘spontaneous’ nucleation driven by the relaxation of the dislocation-related internal stress field. The complexity of the nucleation mechanisms observed here emphasizes the impact of stress and strain heterogeneities on dynamic recrystallization mechanisms.This article is part of the themed issue ‘Microdynamics of ice’.
ISSN: 1364-503X

hal-01467152
https://hal.archives-ouvertes.fr/hal-01467152
DOI : 10.1098/rsta.2015.0345

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Cet article analyse les interactions socioculturelles d’acteurs multiples ayant des intérêts divergents en regard de la reconnaissance d’un espace naturel à titre d’aire protégée, plus particulièrement le Parc marin du Saguenay–Saint-Laurent (PMSSL), situé au Québec à l’embouchure de la rivière Saguenay. Compris dans le sens d’espace socialisé et investi de valeurs parfois contradictoires, ce territoire constitue le cas empirique sur lequel repose l’analyse des logiques d’acteurs. La perspective ici mise de l’avant repose à la fois sur une décision de l’État de créer et de mettre en valeur une aire marine ainsi que sur la participation active des collectivités territoriales dans la gestion du patrimoine environnemental et culturel lié à leur identité propre. Si la participation des communautés locales apparaît comme un élément essentiel et démocratique dans la reconnaissance d’un espace naturel protégé, il apparaît tout aussi capital de bien saisir la logique qui sous-tend les actions de l’État et du milieu. Les résultats empiriques montrent deux logiques d’action distinctes à l’œuvre, une logique classique de planification et implantation stratégiques de l’état réservant une espace de participation programmée pour la communauté et une logique stratégique communautaire à caractère émergent, de portée moins englobante, mais adaptable aux nouvelles réalités et contraintes gouvernementales. Les résultats peuvent être représentés sous forme d’un processus de gouvernance à l’œuvre, un caractérisé par une participation de base, mais un qui suggère qu’un processus plus hautement démocratique nécessiterait un plus haut degré de vigilance dans la perspective communautaire, suffisante pour produire une meilleure symétrie de pouvoir démocratique entre l’État.
This paper analyzes the socio-cultural dynamic between multiple stakeholders with divergent interests concerning the formalization of the status of a natural area into a protected area. The empirical case under analysis is the creation of the Saguenay Marine Park located at the confluence of the St-lawrence and Saguenay rivers in Québec, a rural region represented by different localities showing some contradictions in socio-economic values and agendas. The dual perspective put forth is, first, the governmental decision one to create and promote a marine protected area, and second, the regional community one to participate in the process and adapt the management of their cultural and environmental heritage to their own perception of their socio-economic identity. The objective of analysis is to identify the logics of action underlying both processes. The empirical results show two distinct logics at work, a government logic of classic managerial planning and implementation into which the community has a programmed role and a community logic of emergent planning, less comprehensive in scope, but adaptable to the emerging realities and limitations of the governmnent one. They can be seen in tandem as representing a governance process at work, one with a basic participative character, but one which suggests that an enhanced democratic process entails a higher vigilance level from a community perspective, such as to produce a more even democratic symmetry of powers between the State and the regional community.
Québec

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.3565
http://journals.openedition.org/etudescaribeennes/3565

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We performed torsional deformation experiments on pre-hydrated fine-grained olivine aggregates using an innovative experimental assembly to investigate water weakening in mantle rocks at high shear strains. San Carlos olivine powder was cold-pressed and then hot-pressed under hydrous conditions, producing aggregates with average grain sizes of 7 or 15 μm. Deformation experiments were performed in a high-resolution gas-medium apparatus equipped with a torsional actuator, under a confining pressure of 300 MPa, a temperature of 1200 °C, and constant shear strain rates ranging from 8 × 10−5 to 1.4 × 10−4 s−1. Maximum shear stresses range from 150 to 195 MPa. These values are 30% lower relative to those determined in previous torsion experiments on dry, fined-grained dunites under similar conditions. Textures and microstructures of the starting and deformed specimens were characterized by scanning and transmission electron microscopy. All deformed aggregates exhibit a shape-preferred orientation marking a foliation and lineation, as well as a reduction in mean grain size from 15 μm down to 3-4 μm due to dynamic recrystallization. Olivine crystallographic fabrics developed rapidly (γ < 0.1), but their strength, characterized by the J-index, is low compared to naturally deformed peridotites or to polycrystalline olivine deformed at similar finite shear strains under dry conditions. The crystallographic fabrics are consistent with deformation by a dislocation accommodated creep mechanism with activation of multiple {0 k l}[1 0 0] systems, among which the (0 1 0)[1 0 0] slip system is dominant, and minor participation of the (0 1 0)[0 0 1] slip system. Transmission electron microscopy confirmed the occurrence of dislocations with [1 0 0] and [0 0 1] Burgers vectors in most grains. Analysis of unpolarized infrared spectra indicates that hydrogen concentration in the olivine lattice is below the saturation level of 18 ppm wt H2O, which is similar to those typically observed in spinel-bearing peridotite xenoliths, and also provide evidence for water-rich inter-granular material trapped in pores and grain boundaries. Seismic properties computed from the CPO observations correspond to those most commonly observed in naturally deformed mantle peridotites with fast P-wave propagation and S-wave polarization subparallel to the shear direction. These torsion experiments on fine-grained olivine polycrystals under hydrous conditions indicate that water weakening under lithospheric conditions is linked to various defects with hydrogen in the olivine structure, as well as with water-derived species in grain boundaries or pores.
ISSN: 0031-9201

hal-00745170
https://hal.archives-ouvertes.fr/hal-00745170
DOI : 10.1016/j.pepi.2012.05.001

Éditeur(s) : Gauthier-Villars
Résumé : In contrast to plants, predation on animals is usually lethal. Analysis of the effect of predation on animal populations and on predator-prey dynamics typically assumes this is the case. However, sublethal predation occurs in echinoderms, primarily on the arms of crinoids, asteroids, and ophiuroids. Sublethal predation is important in these echinoderms as it meets one of Harris' (1989) major criteria, affecting basic biological processes such as acquisition of food and allocation of nutrients to growth and reproduction. Sublethal predation would have an effect on their ecological role. It is essential to consider sublethal predation in the analysis of the life-histories of these species.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1996 , Vol. 19 , N. 3-4 , P. 431-440

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00094/20499/18168.pdf
http://archimer.ifremer.fr/doc/00094/20499/