Éditeur(s) : HAL CCSD
Résumé : International audience
Structure and evolution of networks have been areas of growing interest in recent years, especially with the emergence of Social Network Analysis (SNA) and its application in numerous fields. Researches on diffusion are focusing on network modeling for studying spreading phenomena. While the impact of network properties on spreading is now widely studied, involvement of network dynamicity is very little known. In this paper, we address the epidemiology context and study the consequences of network evolutions on spread of diseases. Experiments are conducted by comparing incidence curves obtained by evolution strategies applied on two generated and two real networks. Results are then analyzed by investigating network properties and discussed in order to explain how network evolution influences the spread. We present the MIDEN framework, an approach to measure impact of basic changes in network structure, and DynSpread, a 2D simulation tool designed to replay infections scenarios on evolving networks.
Database and Expert Systems Applications - 22nd International Conference, DEXA 2011, Toulouse, France, August 29 - September 2, 2011, Proceedings, Part II
Toulouse, France

hal-00614925
https://hal.archives-ouvertes.fr/hal-00614925
DOI : 10.1007/978-3-642-23091-2_49

Éditeur(s) : HAL CCSD
Résumé : The concept of network provides a model for representing a wide variety of objects and systems, both natural and social, in which a set of homogeneous or heterogeneous entities interact. It is now widely used to describe various kinds of relational structures. However, if everyone has an idea of the concept of network, we often ignore the implications that these structures have in real world phenomena. This is for example the case of processes such as the spread of a rumor, the disease transmission, or even the emergence of subjects of common interest for a group of individuals, in which the relations maintained between individuals, and their nature, often prove to be the main factors determining the evolution of the phenomenon. This is the reason why the study of networks has become one of the emerging areas in the 21st century called the "Science of networks." In this thesis, we address three issues of the domain of the science of networks: the problem of diffusion in social networks, where we have addressed more particularly the impact of the network dynamics on the diffusion process, the problem of the analysis of social networks, in which we have proposed a solution to take full advantage of all information available on the network by combining information on both structure and node attributes and the central problem of the social data collection, for which we have focused on the particular case of the data collection in a wild environment.
Le concept de réseau offre un modèle de représentation pour une grande variété d'objets et de systèmes, aussi bien naturels que sociaux, dans lesquels un ensemble d'entités homogènes ou hétérogènes interagissent entre elles. Il est aujourd'hui employé couramment pour désigner divers types de structures relationnelles. Pourtant, si chacun a une idée plus ou moins précise de ce qu'est un réseau, nous ignorons encore souvent les implications qu'ont ces structures dans de nombreux phénomènes du monde qui nous entoure. C'est par exemple le cas de processus tels que la diffusion d'une rumeur, la transmission d'une maladie, ou même l'émergence de sujets d'intérêt commun à un groupe d'individus, dans lesquels les relations que maintiennent les individus entre eux et leur nature s'avèrent souvent être les principaux facteurs déterminants l'évolution du phénomène. C'est ainsi que l'étude des réseaux est devenue l'un des domaines émergents du 21e siècle appelé la "Science des réseaux". Dans ce mémoire, nous abordons trois problèmes de la science des réseaux: le problème de la diffusion dans les réseaux sociaux, où nous nous sommes intéressés plus particulièrement à l'impact de la dynamique du réseau sur le processus de diffusion, le problème de l'analyse des réseaux sociaux, dans lequel nous avons proposé une solution pour tirer parti de l'ensemble des informations disponibles en combinant les informations sur la structure du réseau et les attributs des noeuds et le problème central de la collecte de données sociales, où nous nous sommes intéressés au cas particulier de la collecte de données en milieux sauvages.
https://tel.archives-ouvertes.fr/tel-00830882

Droits : info:eu-repo/semantics/OpenAccess
tel-00830882
https://tel.archives-ouvertes.fr/tel-00830882
https://tel.archives-ouvertes.fr/tel-00830882/document
https://tel.archives-ouvertes.fr/tel-00830882/file/These_STATTNER_2012.pdf

Éditeur(s) : HAL CCSD IGI Global
Résumé : International audience
The social behavior of individuals is an important factor of the transmission and the evolution of many diseases. As such, epidemic studies have attempted to integrate social aspects in dissemination modeling. Since the pioneering works of Klovdahl on AIDS in 1985, epidemiological investigations and interventions increasingly focus on social networks. Significant factors of the transmission and outbreak of many infectious diseases are the structure and nature of human interactions. Network-based modeling approaches have found various applications in epidemiology as a simple yet efficient way to represent the complexity of human relationships implicated in dissemination processes. However, most results have been obtained by considering social networks as steady stage structures. Evolving networks have not been explored. The objective is first to give an overview of network-based modeling attempts in epidemiology to analyze and understand the dissemination processes with an emphasis on dynamic networks. The authors approach is designed to understand the impact of social links dynamics on epidemic spread. The authors present the results obtained by combining network evolution patterns (link creation and deletion) and a typical epidemic model. The speed of link dynamics and the infection time strongly influence the occurrence and value of the epidemic peak.
ISSN: 1947-8186

hal-00700105
https://hal.archives-ouvertes.fr/hal-00700105
DOI : 10.4018/jismd.2012070103

Éditeur(s) : HAL CCSD
Résumé : International audience
While the impact of network properties on information spread- ing is now widely studied, in uence of network dynamics is very little known. In this paper, we study how evolution mechanisms tradition- ally observed within social networks can a ect information di usion. We present an approach that merges two models: model of informa- tion di usion through social networks and model of network evolution. Since epidemics provide a reference in application domains of information spreading, we measure the impact of basic network structure changes on epidemic peak value and timing. Then we investigate observed trends in terms of changes appearing in the network structure. Our results provide promising results on how and why network dynamics is a strong param- eter to integrate in requirements for information spreading modelling.
World Summit on the Knowledge Society
Mykonos, Greece

hal-00768405
https://hal.archives-ouvertes.fr/hal-00768405

Éditeur(s) : HAL CCSD
Résumé : International audience
In this work, we focus on the issue of diffusion in dynamic networks. We begin by proposing a generic framework that merges two essential aspects of the problem: diffusion and network dynamics. Then, our framework is used for comparing effects of two aspects of the human behavior, sociability and network dynamics. On the one hand the dynamics of the network is related to the movements of individuals in a social space that lead ephemeral social proximity contacts. On the other hand the diffusion phenomenon is studied through the epidemic paradigm. The results obtained by simulations provide original insight about how and why the "social dynamics" of individuals, related to the proximity in a social space and its evolutions, influences diffusion phenomena through a population.
International Conference on Advances in Social Networks Analysis and Mining
Istanbul, Turkey

hal-00786162
https://hal.archives-ouvertes.fr/hal-00786162
DOI : 10.1109/ASONAM.2012.104

Éditeur(s) : HAL CCSD Society for the Study of Reproduction
Résumé : International audience
Spermmotility notably depends on the structural integrity of the flagellum and the regulation ofmicrotubule dynamics. Although researchers have started to use " omics" techniques to characterize the human sperm's molecular landscape, the constituents responsible for the assembly, organization, and dynamics of the flagellum microtubule have yet to be fully defined. In this study, we defined a core set of 116 gene products associated with the human sperm microtubulome (including products potentially involved in abnormal ciliary phenotypes and male infertility disorders). To this end, we designed and applied an integrated genomics workflow and combined relevant proteomics, transcriptomics, and interactomics datasets to reconstruct a dynamic interactome map. By further integrating phenotypic information, we defined a disease-interaction network; this enabled us to highlight a number of novel factors potentially associated with altered sperm motility and male fertility. Lastly, we experimentally validated the expression pattern of two candidate genes (CUL3 and DCDC2C) that had never previously been associated with male germline differentiation. Our analysis suggested that CUL3 and DCDC2C's products have important roles in the sperm flagellum. Taken as a whole, our results demonstrate that an integrated genomics strategy can highlight relevant molecular factors in specific sperm components. This approach could be easily extended by including other " omics" data (from asthenozoospermic men, for example) and identifying other critical proteins from the human sperm microtubulome. Summary Sentence Although researchers have started to use "omics" techniques to characterize the human sperm's molecular landscape, the constituents responsible for the assembly, organization, and dynamics of the flagellum microtubule have yet to be fully defined.
ISSN: 0006-3363

hal-01515563
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01515563
DOI : 10.1095/biolreprod.116.143479
PUBMED : 28395323

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We propose a new geometric approach to describe the qualitative dynamics of chemical reactions networks. By this method we identify metastable regimes, defined as low dimensional regions of the phase space close to which the dynamics is much slower compared to the rest of the phase space. These metastable regimes depend on the network topology and on the orders of magnitude of the kinetic parameters. Benchmarking of the method on a computational biology model repository suggests that the number of metastable regimes is sub-exponential in the number of variables and equations. The dynamics of the network can be described as a sequence of jumps from one metastable regime to another. We show that a geometrically computed con-nectivity graph restricts the set of possible jumps. We also provide finite state machine (Markov chain) models for such dynamic changes. Applied to signal transduction models, our approach unravels dynamical and functional * corresponding author capacities of signalling pathways, as well as parameters responsible for speci-ficity of the pathway response. In particular, for a model of TGFβ signalling, we find that the ratio of TGFBR2 to TGFBR1 receptors concentrations can be used to discriminate between metastable regimes. Using expression data from the NCI60 panel of human tumor cell lines, we show that aggressive and non-aggressive tumour cell lines function in different metastable regimes and can be distinguished by measuring the relative concentrations of receptors of the two types.
ISSN: 0303-2647

hal-01379033
https://hal.inria.fr/hal-01379033
https://hal.inria.fr/hal-01379033/document
https://hal.inria.fr/hal-01379033/file/Samal_et_al_Biosystems_final.pdf
DOI : 10.1016/j.biosystems.2016.07.004

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Le débat théorique sur les migrations et la famille connait une ambivalence allant du postulat de la migration comme une logique « individualiste » et de distanciation de la famille à celui de la migration vue comme une stratégie de survie portée par le réseau familial. C’est dans le but de contribuer à ce débat que le présent texte aborde l’analyse du processus migratoire sous l’angle des stratégies déployées par les migrants « Hloua » de la côte béninoise. Quatre dimensions ont particulièrement retenu notre attention : la prise de décision, le financement et l’organisation du voyage, l'intégration dans le milieu d’accueil, et les rapports maintenus avec le milieu d'origine.L’analyse s’appuie sur les récits de migration collectés auprès de migrants de retour ou de membres de familles restés au village, ceci dans le cadre d’une enquête plus large sur la pauvreté et les stratégies de survie dans le milieu de la pêche artisanale (Avloh, Ayiguinnou et Agoué) au Bénin. Cette analyse de récit a été complétée par des analyses de type quantitatif sur la fréquence des recours pour l’organisation et la prise de décision, la fréquence de recours pour l’insertion résidentielle et professionnelle, et le montant des envois de fonds. Les résultats montrent la place centrale du réseau familial le long du processus migratoire depuis la prise de décision, l’organisation du voyage, le « confiage » de la femme et des enfants du migrant, à l’établissement résidentiel et l’insertion professionnelle dans le milieu d’accueil. Ce réseau organise et structure efficacement le phénomène migratoire en intervenant lors des étapes décisives. Cependant, une fois insérés, les rapports maintenus avec le réseau familial se limitent pour la plupart à une solidarité affective, caractérisée par des contacts téléphoniques ou transferts de message et quelques envois de fonds largement en deçà des attentes. Ce qui fait dire de plus en plus que le migrant diminue le capital social de la famille sans pour autant y contribuer de façon substantielle sur le plan financier : Un paradoxe qui pourrait bien trouver son explication dans les recherches futures sous une perspective dynamique des migrations.
The theoretical debate on migration and family is ambivalent. Migration can be seen from an “individualist’’ and distant logic of the family or, on the other hand, migration can be viewed as a strategy of survival for the family network. It is in the objective of contributing to this debate, the present article will analyze the migration process from a migrant strategy perspective, more specifically from the perspective of the “Hloua” migrants off the Benin coast. Four dimensions are of particular interest: the decision making process, the cost and organization of the trip, integration in the host community and the maintenance of relations with the host community. Within a large scale research on poverty and the strategies of survival of artisan fishing (Avloh, Ayiguinnou et Agoué) in Bénin, the present analysis is based on migration stories collected from returning migrants or from family members still living in the village. This story analysis has been completed with quantitative analyses on the frequency of the use of organization and decision making, the frequency of the use of residential and professional insertion, and the amount of remittances. The results show the central place of family ties during the migratory process from the start of the decision making process, the travel planning, the entrusting of the women and children of the migrant, to the residential establishment and the professional insertion in the host society. This network organizes and structures efficiently the migratory phenomenon by intervening during the decisive steps. However, once inserted, the connections maintained with the family network are limited for the majority to an affective solidarity characterized by telephone contacts or message transfers, and sometimes remittances sent back largely lower to the family’s expectations. This results more and more in the migrant diminishing the social capital of the family without always contributing in some substantially way on the financial side. A paradox which could find its explanation in future researches under a perspective of migrations’ dynamics.
Bénin

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5785
http://journals.openedition.org/etudescaribeennes/5785

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
While the effects of deforestation and habitat fragmentation on parasite prevalence or richness are well investigated, host-parasite networks are still understudied despite their importance in understanding the mechanisms of these major disturbances. Because fragmentation may negatively impact species occupancy, abundance and co-occurrence, we predict a link between spatiotemporal changes in habitat and the architecture of host-parasite networks. For this, we used an extensive data set on 16 rodent species and 29 helminth species from seven localities of South-East Asia. We analysed the effects of rapid deforestation on connectance and modularity of helminth-parasite networks. We estimated both the degree of fragmentation and the rate of deforestation through the development of land uses and their changes through the last 20 to 30years in order to take into account the dynamics of habitat fragmentation in our statistical analyses. We found that rapid fragmentation does not affect helminth species richness per se but impacts host-parasite interactions as the rodent-helminth network becomes less connected and more modular. Our results suggest that parasite sharing among host species may become more difficult to maintain with the increase of habitat disturbance.
ISSN: 0021-8790

hal-01355307
https://hal.archives-ouvertes.fr/hal-01355307
DOI : 10.1111/1365-2656.12368
IRD : fdi:010064927

Éditeur(s) : HAL CCSD
Résumé : The present PhD thesis is devoted to the numerical simulation and analysis of shear on cohesive granular materials. In the framework of the Contact Dynamics method, we developed a model of cohesive bonding, which mimics cohesion by cementation. This model involves three contact strength parameters (a tensile strength, a coefficient of sliding friction, and a coefficient of rolling friction) as well as a local criterion, which controls the creation and the breaking of cohesive bonds. All contacts are cohesive at the beginning of the numerical simulations, and contact rupture leads to an irreversible loss of tensile strength (debonding). We varied systematically the three contact strength parameters and studied their influence on the shear strength, the dilatancy, and the microstructure of the granular media. Our results show that internal friction and macroscopic tensile strength have different origins at the contact scale. We also find that the microstructure of the granular media, when sheared at the steady state (also known as the `critical state"), is strongly affected by the local coefficients of sliding and rolling friction. In particular, the mechanical role of the weak network changes with these two contact parameters, which results from the formation of a new structure of force transmission. On the other hand, we also applied the same numerical simulation method to the simulation of landslides. We developed a methodology, which takes into account the initial morphology of the hillslope, the strength of geomaterials, and a triggering factor, integrating in the same model the initiation and propagation phases of the landslide. To illustrate this methodology, we applied it to the simulation of a hypothetical example of avalanche triggered by the progressive rise of a water table.
Ce travail de thèse porte sur la modélisation numérique et l'analyse du cisaillement dans les milieux granulaires cohésifs. Dans le cadre de la méthode de la Dynamique des Contacts, nous avons développé un modèle de cohésion qui cherche à imiter la cohésion par cimentation. Ce modèle fait intervenir trois paramètres de résistance au niveau des contacts (une résistance à la traction, un coefficient de frottement de glissement, et un coefficient de frottement de roulement) ainsi qu'un critère de création et de rupture des liens cohésifs. Les contacts sont cohésifs au début des simulations et leur rupture entraîne la perte irréversible de la résistance à la traction. Nous avons fait varier les trois paramètres microscopiques et nous avons étudié leur influence dans la résistance au cisaillement, la dilatance, et la microstructure du milieu. Nos résultats montrent que le frottement interne et l'adhésion macroscopiques ont des origines microscopiques différentes. Nous observons aussi que la microstructure du milieu cisaillé à l'état stationnaire (aussi connu comme ``l'état critique") est fortement affectée par l'angle de frottement et la résistance au roulement au niveau des contacts. En particulier, le rôle mécanique du réseau faible change avec ces deux paramètres microscopiques, ce qui résulte de la formation d'une nouvelle structure de transmission de forces. D'autre part, nous avons appliqué cette méthode de simulation numérique à l'étude d'un processus naturel : les glissements de terrain. Nous avons développé une méthodologie qui tient compte de la morphologie initiale du système, de la résistance des géomatériaux, et d'un mécanisme de déclanchement, ce qui permet d'intégrer dans le même modèle les phases d'initiation et de propagation du glissement. Pour illustrer cette méthodologie, nous l'avons appliquée à la modélisation d'un exemple hypothétique d'avalanche déclenchée par la montée progressive du niveau d'une nappe d'eau.
https://tel.archives-ouvertes.fr/tel-00311303

tel-00311303
https://tel.archives-ouvertes.fr/tel-00311303
https://tel.archives-ouvertes.fr/tel-00311303/document
https://tel.archives-ouvertes.fr/tel-00311303/file/these_estrada.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) : Université des Antilles Études caribéennes
Résumé : Sur fond de crise du tourisme au Nord, de la globalisation de l’économie et de l’accélération des mobilités, une évolution des formes de développement touristiques semble à l’œuvre dans les confins géographiques. Dans certains territoires touristiques du fait de conflits dans l’usage des ressources naturelles, des pratiques récréatives alternatives émergent qui combinent une logique économique avec des préoccupations socio-environnementales.Notre article analyse l’apparition du tourisme scientifique dans la région « non-touristique » de Aysén, en Patagonie chilienne. Des acteurs d’un territoire se mobilisent selon des pôles culturels et des axes thématiques autour de projets pilotes, de recherche expérientielle et de médiations scientifiques innovantes. Sur ce front pionnier, un réseau informel d’acteurs coordonne ses actions pour aborder les problématiques sociales et environnementales de leur territoire. Opérateurs et prestataires pour le tourisme scientifique créent de manière participative une offre originale. Un système touristique alternatif, axé sur la protection de l’environnement, de la culture et des dynamiques sociales de la communauté d’accueil, favorise l’acquisition et le partage de savoirs entre scientifiques, acteurs locaux et visiteurs.Le tourisme scientifique s’inscrit-il dans une évolution globale des pratiques touristiques ? En proposant de dépasser les frontières, entre activités récréatives et le travail, de lieux de vie et de loisir, il apparaît comme l’expression d’un « après-tourisme ». L’hybridation des pratiques, une approche scientifique associée à l’esprit de la découverte inhérent au voyage, semble pouvoir relever des défis sociétaux liés à l’essor d’un tourisme globalisé. Alors que le tourisme est pensé depuis longtemps en termes de transfert de compétences, de modèles et d’ingénierie du Nord vers le Sud, une périphérie propose de nouveaux cadres de pensée, d’action et de participation qui renouvellent le sens du voyage.
In the context of a tourism crisis in the north, a globalized economy and an increase of mobility, a change in the forms of tourism development seems to occur in peripheral areas. In some tourism areas and due to conflicts over the use of natural resources, alternative recreational practices arise that combine economic needs and socio-environmental concerns.Our article analyzes the appearance of scientific tourism in the "non-tourist" region of Aysén, in Chilean Patagonia. Actors of a territory unite according to specific cultural poles and thematic axes through experiential research and innovative scientific mediation pilot projects. On this pioneer front, an informal network of stakeholders coordinates its actions to address the social and environmental issues of their territory. Operators and service providers for scientific tourism create an innovative offer in a participatory process. An alternative tourism system, focused on protecting the environment, the culture and social dynamics of the host community, promotes the acquisition and sharing of knowledge between scientists, local actors and visitors.Is scientific tourism part of a global evolution of tourism practices? By proposing to go beyond established boundaries, of recreational activities and work, everyday places and leisure areas, it appears as the expression of an “After-Tourism”. The hybridization of practices, a scientific approach associated with the spirit of the discovery inherent of the travel experience, seems to respond to the challenges of the community confronted to the rise of a globalized tourism. While tourism has always been thought of in terms of transfer of skills, models and engineering from the North to the South, a periphery offers new frameworks of thought, action and participation that renew the meaning of travel.
En un escenario de crisis del turismo en los países desarrollados, de la globalización de la economía y del incremento de las movilidades, una evolución de las formas de desarrollo del turismo parece estar en marcha en los confines geográficos. En ciertos territorios turísticos, debido a los conflictos de uso de los recursos naturales, prácticas recreativas alternativas surgen que combinan una lógica económica con preocupaciones socio-ambientales.El presente artículo analiza el surgimiento del turismo científico en la región “no-turística” de Aysén en la Patagonia chilena. Actores del territorio se unen según polos y temáticas científicas, a través de proyectos pilotos, de investigación experiencial y mediaciones científicas innovadoras. En este frente pionero, una red informal se organiza para abordar las problemáticas sociales y ambientales de su territorio. Operadores y proveedores de servicios para el turismo científico crean de manera participativa una oferta novedosa. Un sistema turístico alternativo, basado en el cuidado del medio ambiente, de la cultura y de las dinámicas sociales del comunidad de acogida, favorece la adquisición y el intercambio de conocimientos entre científicos, actores locales y visitantes. ¿Será la aparición del turismo científico la expresión de una evolución global de las practicas turísticas? Al invitar a que sean sobrepasadas las fronteras, entre actividades recreativas y el trabajo, lugares de vida y sitios de esparcimiento, este se presenta como un “Pos-Turismo”. La hibridación de las prácticas, una aproximación científica asociada al espíritu de descubrimiento inherente del viaje, parece poder resolver los desafíos de nuestras sociedades vinculados al auge de un turismo globalizado. Cuando el turismo suele ser pensado desde hace mucho, como un proceso de transferencia de capacidades, de modelos y de ingenierías, del Norte hacia el Sur, una periferia propone nuevos marcos conceptuales, de acción y de participación, que renuevan el sentido del viaje.
Patagonie

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.11169
http://journals.openedition.org/etudescaribeennes/11169

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The actin cytoskeleton is a dynamic structure that provides an interactive platform for organelles and cellular components. It also serves as track for membranes and vesicles that move via myosin. The actin cytoskeleton of Symbiodinium is a well-organized reticular structure suggestive of multiple membrane interactions, very likely including those of the chloroplast. The Symbiodinium chloroplast membrane network is, in turn, a highly organized structure, suggestive of being under the control of an organizing network. We visualized the chloroplast membranes of cultured Symbiodinium sp. under various light conditions and observed changes dependent on illumination intensity. Since we suspected interaction between these two organelles, and we knew that the Symbiodinium actin cytoskeleton collapses upon treatment with either latrunculin B, an actin microfilament-disrupting agent, or butanedione monoxime, a myosin function inhibitor, we tested the Symbiodinium sp. oxygen evolution in their presence. Upon latrunculin B addition, the oxygen production decreased compared to non-treated cells; however, this was not observed after a 24 h latrunculin treatment. On the contrary, butanedione monoxime treatment caused a non-recoverable dysfunction of the chloroplast causing a severe loss in oxygen production even after long-term exposure. Using electron microscopy, we observed an alteration of the Symbiodinium sp. chloroplast distribution after latrunculin B treatment, with respect to untreated cells. Furthermore, a thorough disorganization of the chloroplast grana was observed after butanedione monoxime treatment. These data suggest that an actomyosin system would be important for chloroplast organization and distribution, and critical for normal photosynthetic function of Symbiodinium sp.
ISSN: 0166-8595

hal-01546164
https://hal.archives-ouvertes.fr/hal-01546164
DOI : 10.1007/s11120-015-0142-9

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Structural controls are critical during magmatic-to-hydrothermal transition in the formation of intrusion-related gold deposits. They may explain why only some parts of intrusions are mineralized and why only very few intrusions host large deposits. Moreover, most of these gold deposits postdate peak regional metamorphism and were formed in zones of relatively low strain. Indeed, the efficiency of structural gold traps is highest along favourably oriented intrusion/host-rock contacts where mechanical instability maintains high permeability in the cracked thermal aureole. This may be reinforced by melt injections from an underlying root zone. We present a structural analysis of the deformation features of a granite-pluton roof; large-scale dykes and a network of gold veins are intensively developed in this roof, recording a succession of mechanical instabilities. Our gravity survey underlines the presence of a pluton feeder zone located just beneath the mineralized network. It is argued that interferences between regional stress and melt injection in the feeder zone favoured the development of the network by strain located close to the granite roof. This stresses the role of mechanical instabilities triggered by the combined effects of regional stress and melt dynamics in determining the location and size of this type of gold deposit.
ISSN: 0191-8141

insu-00914780
https://hal-insu.archives-ouvertes.fr/insu-00914780
https://hal-insu.archives-ouvertes.fr/insu-00914780/document
https://hal-insu.archives-ouvertes.fr/insu-00914780/file/manuscript.pdf
DOI : 10.1016/j.jsg.2013.11.006

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) : HAL CCSD
Résumé : International audience
In this work, we have led an analysis of the error of different global solar radiation prediction models according to the global solar radiation variability. Different predictions models where performed such as machine learning techniques (Neural Networks, Gaussian processes and support vector machines) in order to forecast the Global Horizontal solar Irradiance (GHI). We also include in this study a simple linear autoregressive (AR) model as well as two naive models based on persistence of the GHI and persistence of the clear sky index (denoted herein scaled persistence model). The models are calibrated and tested with data from three 3 French islands: Corsica (42.15°N ; 9.08°E), Guadeloupe (16.25°N ; 61.58°W) and Reunion (21.15°S ; 55.5°E). Guadeloupe and Reunion are located in a subtropical climatic zone whereas Corsica is in a tempered climatic zone. Hence the global solar radiation variation differs significantly. The output error of the different models was quantified by the nRSME. In order to quantify the influence of the global solar radiation variability on the forecasting models error we performed a classification of typical days according to different typical days. Each class of typical day is defined by a variation of global solar radiation rate. For each class and for each location, the selected forecasting models where performed and the error was quantified. With this analysis a global solar radiation forecasting models can be selected according to the location, the global solar radiation fluctuations and hence the meteorological conditions. INTRODUCTION Large and frequent variations of solar radiation can be observed in tropical climates with amplitudes reaching 800 W/m² and occurring within a short time interval, from few seconds to few minutes, according to the geographical location. Such fluctuations can be due for example to the dynamic of clouds which can be very complex and depend on cloud type, size, speed and spatial distribution and, more generally, due to some specific local meteorological conditions. Thus, the solar energy forecasting, a process used to predict the amount of solar energy available in the current and near terms, might be a difficult task. Some of the best predictors found in literature are Autoregressive and moving average (ARMA) [5,7,8], Bayesian inferences [9,10], Markov chains [11], k-Nearest-Neighbors predictors [12] or artificial intelligence techniques as the Artificial Neural Network (ANN) [9-11]. Although these methodologies are potentially good in many areas, we observed in our previous studies on global radiation prediction [9,13,14] that the simple model based on the persistence of the clear sky index gives often very good results with acceptable errors [15] for short term forecasting time horizon (<= 1 hour). The goal of this paper is to determinate the influence of solar radiation variability regarding different classes of days on the expected error provided by different forecasting methods that the modeller can possibly implement. The paper is organized as follow: Section 2 describes the data we have used. Section 3 exposes the classification methodology and the results obtained for the three studied locations. In the two following sections, the forecasting methods are exposed and then 3 the errors on the forecasting results for each location and for each class are exposed.
The Third Southern African Solar Energy Conference (SASEC2015)
Kruger National Park, South Africa

Droits : info:eu-repo/semantics/OpenAccess
hal-01099487
https://hal.archives-ouvertes.fr/hal-01099487
https://hal.archives-ouvertes.fr/hal-01099487/document
https://hal.archives-ouvertes.fr/hal-01099487/file/article%20SASEC.pdf

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
Traditional network generation models aim to replicate global structural properties observed on various real-world networks through synthetic link formation mechanisms such as triadic closure or preferential attachment. Nowadays, the large amount of data available allow to study more precisely the link formation processes and to compare models with real situations. In this work, we analyze the network formed by the communication activities of the users of a telephony operator for studying the link formation process. Our goal is to identify the underlying formation mechanisms and checking if they match those proposed in traditional models. Indeed, the communications emitted and received by users are strong indicators for understanding the underlying patterns of the link formation process and highlighting how some individual properties induce the formation process in such a network. In a first study conducted at a global level, we show that the traditional mechanisms commonly used in network generation models cannot reproduce alone the link formation in this network. In a second study, we adopt a new point of view and analyze locally the link formation process by searching for correlations between some user attributes and the formation of the new links. The results obtained show that a very strong percentage of new links are formed between individuals with strong similarity.
ISSN: 1869-5450

hal-01312310
https://hal.univ-antilles.fr/hal-01312310
DOI : 10.1007/s13278-015-0304-y

Éditeur(s) : HAL CCSD American Physical Society
Résumé : International audience
We investigate a class of granular materials characterized by the possibility of interlocking between the particles. The interlocking is modeled by its effect through rolling resistance depending on relative rotation and normal force at the contact points and involving a single parameter analogous to the sliding friction coefficient. The model, which is introduced in the framework of the contact dynamics, method, is applied to simulate the simple shear of a large granular sample. We present a detailed analysis regarding the influence of rolling and sliding friction parameters on the macroscopic response in terms of shear strength, fabric properties, and force transmission. Interestingly, two distinct regimes can be distinguished in which the steady-state shear strength is controlled by either rolling resistance or sliding friction. The relative contributions of rolling and sliding contacts to the shear strength are consistent with the same two regimes. Interlocking strongly affects the force network by enhancing the arching effect and thus increasing the relative importance of weak contact forces and torques, which is reflected in a decreasing power-law probability distribution of the contact forces and torques below the mean. Due to the combined effect of friction and interlocking, the force-carrying backbone takes an increasingly columnar aspect involving a low fraction of particles. Our data suggest that the nature of the weak contact network is strongly affected by the formation of these columns of particles which do not need to be propped laterally. In particular, in the limit of high rolling resistance and sliding friction, the role of the weak network of contacts is no longer to prop the force chains, but, like the strong contact network, to actively sustain the deviatoric load imposed on the system.
ISSN: 1539-3755

hal-00412020
https://hal.archives-ouvertes.fr/hal-00412020
DOI : 10.1103/PhysRevE.78.021301

Éditeur(s) : HAL CCSD
Résumé : International audience
Human spatial motions determine geographic social contacts that influence the way an information is spread on a population or a community. As mobility is a transverse dimension to social practices it is important to better understand its role. With the Eternal-Return model we propose, we simulate an artificial world populated by heterogeneous agents who differ in their mobility. We have chosen a multi-agent framework perspective for this simulation. We endow the agents with simple rules on how to move around the space and how to establish proximity-contacts. This allows to distinguish different kinds of mobile agents, from sedentary ones to travelers. To summarize the dynamics induced by mobility over time, we define the mobility-based Social Proximity Network as being the network of all distinct contacts between agents. Its properties give insight in the process of information spreading. We conduct simulations to understand how an information can be broadcast when agent-nodes are in motion.
IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining
Niagara falls, Canada

hal-00874344
https://hal.archives-ouvertes.fr/hal-00874344

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In oblique collision settings, parallel and perpendicular components of the relative plate motion can be partitioned into different structures of deformation and may be localized close to the plate boundary, or distributed on a wider region. In the Southern Alps of New Zealand, it has been proposed that one-third of the regional convergence is distributed in a broad area along the Southern Alps orogenic wedge. To better document and understand the regional dynamics of such systems, reliable markers of the horizontal tectonic motion over geological time scales are needed. River networks are able to record a large amount of distributed strain and they can thus be used to reconstruct the mode and rate of distribution away from major active structures. To explore the controls on river resilience to deformation, we develop an experimental model to investigate river pattern evolution over a doubly-vergent orogenic wedge growing in a context of oblique convergence. We use a rainfall system to activate erosion, sediment transport and river development on the model surface. At the end of the experiment, the drainage network is statistically rotated clockwise, confirming that rivers can record the distribution of motion along the wedge. Image analysis of channel time-space evolution shows how the fault-parallel and fault-perpendicular components of motion decrease toward the fault and impose rotation to the main trunk valleys. However, rivers do not record the whole imposed rotation rate, which suggest that the natural lateral channel dynamics can alter the capacity of rivers to act as passive markers of deformation.
ISSN: 0040-1951

hal-01467564
https://hal.archives-ouvertes.fr/hal-01467564
DOI : 10.1016/j.tecto.2016.04.016