Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Adult fish exhibit a strong neurogenic capacity due to the persistence of radial glial progenitor cells. In zebrafish, radial glial cells display well-established markers such as the estrogen-synthesizing enzyme (AroB) and the brain lipid binding protein (Blbp), which is known to strongly bind omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA). While Blpb is mainly described in the telencephalon of adult zebrafish, its expression in the remaining regions of the brain is poorly documented. The present study was designed to further investigate Blbp expression in the brain, its co-expression with AroB, and its link with radial glial cells proliferation in zebrafish. We generated a complete and detailed mapping of Blbp expression in the whole brain and show its complete co-expression with AroB, except in some tectal and hypothalamic regions. By performing PCNA and Blbp immunohistochemistry on cyp19a1b-GFP (AroB-GFP) fish, we also demonstrated preferential Blbp expression in proliferative radial glial cells in almost all regions studied. To our knowledge, this is the first complete and detailed mapping of Blbp-expressing cells showing strong association between Blbp and radial glial cell proliferation in the adult brain of fish. Given that zebrafish is now recognized models for studying neurogenesis and brain repair, our data provide detailed characterization of Blbp in the entire brain and open up a broad field of research investigating the role of omega-3 polyunsaturated fatty acids in neural stem cell activity in fish
ISSN: 1567-133X

hal-01237088
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01237088
DOI : 10.1016/j.gep.2015.11.003
PUBMED : 26611722

Éditeur(s) : HAL CCSD European Geosciences Union (EGU)
Résumé : International audience
Climate models project that rising atmospheric carbon dioxide concentrations will increase the frequency and the severity of some extreme weather events. The flood events represent a major risk for populations and infrastructures settled on coastal lowlands. Recent studies of lagoon sediments have enhanced our knowledge on extreme hydrological events such as palaeo-storms and on their relation with climate change over the last millennium. However, few studies have been undertaken to reconstruct past flood events from lagoon sediments. Here, the past flood activity was investigated using a multi-proxy approach combining sedimentological and geochemical analysis of surfaces sediments from a southeastern Tunisian catchment in order to trace the origin of sediment deposits in the El Bibane Lagoon. Three sediment sources were identified: marine, fluvial and aeolian. When applying this multi-proxy approach on core BL12-10, recovered from the El Bibane Lagoon, we can see that finer material, a high content of the clay and silt, and a high content of the elemental ratios (Fe ∕ Ca and Ti ∕ Ca) characterise the sedimentological signature of the palaeo-flood levels identified in the lagoonal sequence. For the last century, which is the period covered by the BL12-10 short core, three palaeo-flood events were identified. The age of these flood events have been determined by 210Pb and 137Cs chronology and give ages of AD 1995 ± 6, 1970 ± 9 and 1945 ± 9. These results show a good temporal correlation with historical flood events recorded in southern Tunisia in the last century (AD 1932, 1969, 1979 and 1995). Our finding suggests that reconstruction of the history of the hydrological extreme events during the upper Holocene is possible in this location through the use of the sedimentary archives.
ISSN: 1814-9324

hal-01571962
https://hal.archives-ouvertes.fr/hal-01571962
https://hal.archives-ouvertes.fr/hal-01571962/document
https://hal.archives-ouvertes.fr/hal-01571962/file/affouri2017.pdf
DOI : 10.5194/cp-13-711-2017

Éditeur(s) : HAL CCSD
Résumé : International audience
The paper proposes a new knowledge discovery method called MAX-FLMin for extracting frequent patterns in social networks. Unlike traditional approaches that mainly focus on the network topological structure, the originality of our solution is its ability to exploit information both on the network structure and the attributes of nodes in order to elicit specific regularities that we call "Frequent Links". This kind of patterns provides relevant knowledge about the groups of nodes most connected within the network. First, we detail the method proposed to extract maximal frequent links from social networks. Second, we show how the extracted patterns are used to generate aggregated networks that represent the initial social network with more semantics. Qualitative and quantitative studies are conducted to evaluate the performances of our algorithm in various configurations.
Database (Weston, Conn.) and Expert Systems Applications
Vienna, Austria

hal-00767052
https://hal.archives-ouvertes.fr/hal-00767052
DOI : 10.1007/978-3-642-32600-4_35

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 Elsevier
Résumé : International audience
Wood debris are an important component of mangrove marine environments. Current knowledge of the ecological role of wood falls is limited by the absence of information on metazoan colonization processes over time. The aim of this study was to provide insights to their temporal dynamics of wood eukaryotic colonization from a shallow water experiment in a mangrove swamp. Combined in situ chemical monitoring and biological surveys revealed that the succession of colonizers in the mangrove swamp relates with the rapid evolution of sulfide concentration on the wood surface. Sulfide-tolerant species are among the first colonizers and dominate over several weeks when the sulfide content is at its maximum, followed by less tolerant opportunistic species when sulfide decreases. This study supports the idea that woody debris can sustain chemosynthetic symbioses over short time-scale in tropical shallow waters.
ISSN: 0141-1136

hal-01545913
https://hal.archives-ouvertes.fr/hal-01545913
DOI : 10.1016/j.marenvres.2013.03.007

Éditeur(s) : HAL CCSD SciTePress
Résumé : International audience
Data integration and knowledge capitalization combine data and information coming from different data sources designed by different experts having different purposes. In this paper, we propose to assist the underlying model merging activity. For close models made by experts of various specialities, we partially automate the identification of a Greatest Common Model (GCM) which is composed of the common concepts (core concepts) of the different models. Our methodology is based on Formal Concept Analysis which is a method of data analysis based on lattice theory. A decision tree allows to semi-automatically classify concepts from the concept lattices and assist the GCM extraction. We apply our approach on the EIS-Pesticide project, an environmental information system which aims at centralizing knowledge and information produced by different specialized teams.
ICEIS 2012: 14th International Conference on Enterprise Information Systems
Wroclaw, Poland

lirmm-00727009
https://hal-lirmm.ccsd.cnrs.fr/lirmm-00727009

Éditeur(s) : HAL CCSD IGI Global
Résumé : International audience
Standard data mining techniques have been applied and adapted for eliciting knowledge from social networks, by achieving classical tasks such as classification, search for frequent patterns or link prediction. Most works have exploited only the network topological structure, and therefore cannot be used to answer questions involving nodes features. For instance, the frequent pattern discovery task generally refers to the search for sub-networks frequently found in a single network or in a set of networks. In the same area, this paper focuses on the concept of frequent link that stands as a regularity found in a network on links between node groups that share common characteristics. The extraction of such links from a social network is a particularly challenging and computationally intensive problem, since it is much dependent on the number of links and attributes. In this study, we propose a solution for reducing the search space of frequent links, by filtering the nodes features on a criterion of frequency. We make the assumption that frequent links occur between sets of features that are themselves frequent. This property is used to reduce the search space and speed up the extraction process. We empirically show that it is well founded. We discuss the efficiency of the solution in terms of computation time and number of frequent patterns found depending on several frequency thresholds.
ISSN: 1947-8186

hal-00786166
https://hal.archives-ouvertes.fr/hal-00786166

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ciguatera Fish Poisoning (CFP) is a non-bacterial seafood poisoning well characterized in the remote archipelagos of French Polynesia, yet poorly documented in the Society archipelago, most notably on Moorea, the second most populated island in French Polynesia, which counts a high proportion of fishermen fishing on a regular basis. To address this knowledge gap, a holistic study of the ciguatera issue was conducted on Moorea. First, ciguatera risk was analysed in terms of incidence rate, fish species most commonly involved and risk stratification in Moorea lagoon based on 2007–2013 epidemiological data. A mean incidence rate of 8 cases per 10,000 inhabitants for the study period and an average under-reporting rate of 54% were found. Taking into account hospitalization and medication fees, and loss of productive days, the health-related costs due to CFP were estimated to be USD $1613 and $749 for each reported and unreported case, respectively, with an overall cost of USD $241,847 for the study period. Comparison of the present status of CFP on Moorea with a risk map established in the late 1970’s showed that the spatial distribution of the risk has stayed relatively stable in time, with the north shore of the island remaining the most prone to ciguatera. Evaluation of the current knowledge on CFP among different populations groups, i.e. fishermen, residents and visitors, was also conducted through direct and indirect interviews. About half of the fishermen interviewed were actually able to identify risky fishing areas. While, overall, the CFP risk perception in the fishing community of Moorea seemed accurate, although not scientifically complete, it was sufficient for the safe practice of their fishing activities. This may be due in part to adaptive responses adopted by 36% of the fishermen interviewed, such as the avoidance of either high-risk fishing sites or toxic species. At the residents and visitors’ level, the study points out a striking lack of awareness of the CFP issue among visitors, as compared to local residents. Indeed, less than 25% of Moorea visitors vs. an average of 98% in residents were aware of CFP or of its presence on the island. Interestingly, evaluation of the fish consumption preferences showed that 70% of visitors do not consume lagoon fish during their stay, not for fear of CFP, but mainly due to the lack of availability of these species in recreational facilities or because they have nutritional preference for pelagic fish. This lack of awareness, along with the report by several CFP patients of the consumption of fish species yet banned for sale, stress the need for improved communication efforts on this critical issue among both residents and visitors on Moorea. The implementation of a public outreach strategy is proposed, based on both existing information networks and low-cost communication actions through information displays at various strategic locations, e.g. Tahiti-Faa’a international airport, the ferry boat station, recreational facilities, as well as the major trading points on Moorea Island.
ISSN: 1568-9883

hal-01391648
https://hal-univ-perp.archives-ouvertes.fr/hal-01391648
DOI : 10.1016/j.hal.2016.10.003

Éditeur(s) : HAL CCSD Hindawi Publishing Corporation
Résumé : During the 1982-1984 bradyseismic crises in the Campi Flegrei area (Italy), the University of Wisconsin deployed a network of seismological stations to record local earthquakes. In order to analyse the potential of the recorded data in terms of tomographic imaging, a blind test was recently set up and carried out in the framework of a research project. A model representing a hypothetical 3D structure of the area containing the Campi Flegrei caldera was also set up, and a synthetic dataset of time arrivals was in turn computed. The synthetic dataset consists of several thousand P- and S-time arrivals, computed at about fourteen stations. The tomographic inversion was performed by four independent teams using different methods. The teams had no knowledge of either the input velocity model or the earthquake hypocenters used to create the synthetic dataset. The results obtained by the different groups were compared and analysed in light of the true model. This work provides a thorough analysis of the earthquake tomography potential of the dataset recording the seismic activity at Campi Flegrei in the 1982-1984 period. It shows that all the tested earthquake tomography methods provide reliable low-resolution images of the background velocity field of the Campi Flegrei area, but with some differences. However, none of them succeeds in detecting the hypothetical structure details (i.e. with a size smaller than about 1.5-2 km), such as a magmatic chamber 4 km deep and especially the smaller, isolated bodies, which represent possible magmatic chimneys and intrusions.
ISSN: 1687-885X

hal-00795584
https://hal.archives-ouvertes.fr/hal-00795584
DOI : 10.1155/2012/505286

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Africa faces a number of unique environmental challenges. Unfortunately, it lacks the infrastructure needed to support the comprehensive environmental studies that could provide the scientific basis to inform environmental policies. There are a number of known sources of endocrine-disrupting chemicals (EDCs) and other hazardous chemicals in Africa. However, a coordinated approach to identify and monitor these contaminants and to develop strategies for public health interventions has not yet been made. OBJECTIVES: This commentary summarizes the scientific evidence presented by experts at the First African Endocrine Disruptors meeting. We describe a "call to action" to utilize the available scientific knowledge to address the impact of EDCs on human and wildlife health in Africa. DISCUSSION: We identify existing knowledge gaps about exposures to EDCs in Africa and describe how well-designed research strategies are needed to address these gaps. A lack of resources for research and a lag in policy implementation slows down intervention strategies and poses a challenge to advancing future health in Africa. CONCLUSION: To address the many challenges posed by EDCs, we argue that Africans should take the lead in prioritization and evaluation of environmental hazards, including EDCs. We recommend the institution of education and training programs for chemical users, adoption of the precautionary principle, establishment of biomonitoring programs, and funding of community-based epidemiology and wildlife research programs led and funded by African institutes and private companies. https://doi.org/10.1289/EHP1774.
Environmental Health Perspectives

hal-01616487
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616487
DOI : 10.1289/EHP1774
PUBMED : 28935616

Éditeur(s) : HAL CCSD
Résumé : International audience
Semantic web standards, tools, ontologies and related technologies have considerably matured in the recent years. Nowadays, accessing a wide catalogue of biological, social, environmental, and ecological data sources helps stakeholders working on biodiversity to answer their complex questions. Will the real time access to web resources effectively support the definition of strategies to conserve and manage biodiversity? How might semantic web technologies help us to handle the complex and heterogeneous big data related to biodiversity? The workshop aims to identify the key challenges faced by the bioinformatics community, discuss potential solutions and identify the opportunities emerging from the trans-disciplinary interactions between Plant Science and Informatics experts. Therefore, we expect the bioinformatics experts to explain how they apply semantic web standards and tools to their scientific topic, from biology, agriculture, agro-ecology, genomics, environmental studies, to social sciences, citizen sciences. Research papers presenting various aspects of semantic web technologies applied to biodiversity data, ranging from position papers to implemented systems descriptions and their evaluation, will be selected. We are particularly interested in the use of the semantic technologies to design and develop systems that supports research on agricultural and wild biodiversity conservation and management for food security. Examples may include strategies for resilience to climate change pressures, sustainability of productive ecosystems, ecosystems services monitoring or territories management, rather than systems supporting only research on climate patterns or soil erosion.
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757

lirmm-00831757
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757/document

Éditeur(s) : HAL CCSD
Résumé : International audience
Geographic Information Systems (GIS) help addressing geographical and environmental issues by providing information about a region or a city as a set of maps (layers), each one displaying information about a given theme like roads, vegetation, tourist spots or museums for instance. By combining different layers on a region, one can associate a given area to characteristics from their related themes. Indeed, the information from two or more layers might be merged and then transformed into a new layer as defined in map "algebra". When a theme vocabulary is organized as a taxonomy with concepts linked by is-a relationships, there are different ways to annotate an area with a concept depending on the level selected into the layer taxonomy. In this paper, we present an heuristic- based approach for an optimal merging of such layers in a GIS. Our goal is to generate new layers which sum up information from several themes in a most useful way. Two optimization criteria are considered, the average size of resulting areas and the average informative value of their resulting annotation. We demonstrate the validity of the proposed solution, firstly, on a formal example, and then, on a real world application.
Proceedings of the 4th International Conference on Advanced Geographic Information Systems, Applications, and Services
Valencia, Spain

hal-00679555
https://hal.archives-ouvertes.fr/hal-00679555

Éditeur(s) : SéretB. & J.-Y. Sire, eds Paris: Soc. Fr. lchtyol. & IRD, 2000: 29-45
Résumé : Forty one manned submersible dives were carried out during 2 cruises in the Bay of Biscay covering a range of depth from about 100 to 2100 m. Chondrichthyan species were observed in most of the dives, some of them were easily identified and their behaviour could be studied. Twenty-two chondrichthyan species (9 sharks, 8 rays and 5 chimaeras) were recorded. Shark species were always seen active except Scyliorhinus canicula and Galeus melastomus. Some representatives were found motionless on the bottom, sometimes forming groups for the first species. Chimaeras appeared to strongly react to the presence of the submersible. The density of chondrichtyes and their relative frequency in the total fish assemblage were estimated, the results are globally consistent with former knowledge and the differences with results from trawl surveys are discussed. The observations presented here suggest peak of Chimaera monstrosa abundance at upper slope depth (200-500 m) that was not documented formerly for that area.
Quarante et une plongées en submersible habité ont été effectuées lors de 2 campagnes dans le Golfe de Gascogne par des profondeurs de 100 à 2100 m environ. Des Chondrichtyens ont été observés au cours de la plupart des plongées, 22 espèces (9 requins, 8 raies et 5 chimères) ont été identifiées et leurs comportements ont pu être étudiés. Les requins étaient toujours actifs sauf Scyliorhinus canicula et Galeus melastomus dont certains représentants ont été trouvés immobiles sur le fond, parfois en groupe pour la première espèce. Les chimères se sont montrées très réactives à la présence du submersible. Les densités et fréquences relatives pour l'ensemble des Chondrichtyens ont été estimées, les résultats sont globalement cohérents avec les estimations antérieures; les différences avec les estimations issues de chalutages sont discutées. Les observations présentées ici suggèrent qu'il existe un pic d'abondance de Chimaera monstrosa à la profondeur de la pente supérieure (200-500 m). Ce pic n'avait pas été observé précédemment dans cette zone.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2000/acte-2571.pdf
http://archimer.ifremer.fr/doc/00000/2571/

Résumé : Favorisées par les gouvernants en quête d’un nouveau modèle post-industriel, les économies basées sur la connaissance vont devenir en quelques décennies le référentiel à atteindre pour le développement de territoires soumis aux pressions de la globalisation.Longtemps considérés comme des éléments indispensables à la production et à la transmission du savoir, les établissements d’enseignement supérieur et de recherche, comme les universités, ont été de plus en plus intégrés dans les analyses sur le développement territorial à mesure que s’imposait le paradigme américain de la valorisation des activités de la recherche publique. Cette nouvelle mission imposée aux établissements de recherche, suppose qu’ils sont des facteurs d’un développement localisé. Mais le rôle qui leur est assigné est-il justifié ? À travers l’impact singulier de la recherche publique, on peut analyser la place de ces établissements sur leur territoire d’accueil. Apres avoir fait un état de l’art en matière d’analyse d’impact nous utilisons le cadre méthodologique de l’étude d’un cas illustrant cette problématique. L’agglomération de Brest mise sur la forte concentration d’établissements de recherche à vocation maritime pour développer le cluster local. Bien que non généralisable, ce cas éclaire les recherches dans ce domaine. Au-delà, la thèse apporte une autre vision sur les réformes de type top down des systèmes d’enseignement supérieur et de recherche considérant le savoir comme n’importe quel bien économique. Or la connaissance n’est pas un bien comme les autres. Et c’est cette singularité qui explique les difficultés d’analyse dans le champ de l’économie de la connaissance.
Promoted by governments seeking for a new post-industrial model, the knowledge-based economies will become in a few decades the repository to reach for the development of territories subject to the pressures of globalization. Regarded as essential to the production and transmission of knowledge, higher education and research institutions, such as universities, have been increasingly integrated into the analysis of territorial development while was emerging the american paradigm for valorisation of public research activities. This new mission imposed on research institutions, assume they are factors of localized development. Is this assigned role justified? Through the singular impact of public research, we can analyze the role of these institutions on their home territory. After a state of the art on the impact assessments, we developed a methodological framework for case study illustrating this problem. In the agglomeration of Brest, there is a high concentration of research institutions with maritime vocation on which rely the local cluster. Although not generalizable, this case enlightens the research in this domain. In addition, the thesis sheds new light on the top-down reforms of higher education and research systems considering knowledge as any economic good. But knowledge is not a commodity like others. And that would explain the difficulties of analysis in the field of the knowledge economy.

http://www.theses.fr/2014AGUY0807/document

Éditeur(s) : HAL CCSD
Résumé : International audience
Cumulative human impacts have led to the degradation of marine ecosystems and thedecline of biodiversity in the European and contiguous seas. Effective conservationmeasures are urgently needed to reverse these trends. Conservation must entail societalchoices, underpinned by human values and worldviews that differ between the countriesbordering these seas. Social, economic and political heterogeneity adds to the challenge ofbalancing conservation with sustainable use of the seas. Comprehensive macro-regionalcoordination is needed to ensure effective conservation of marine ecosystems andbiodiversity of this region. Under the European Union Horizon 2020 framework programme,the MarCons COST action aims to promote collaborative research to support marinemanagement, conservation planning and policy development. This will be achieved bydeveloping novel methods and tools to close knowledge gaps and advance marineconservation science. This action will provide support for the development of macro-regional and national policies through six key actions: to develop tools to analysecumulative human impacts; to identify critical scientific and technical gaps in conservationefforts; to improve the resilience of the marine environment to global change and biologicalinvasions; to develop frameworks for integrated conservation planning across terrestrial,freshwater, and marine environments; to coordinate marine conservation policy acrossnational boundaries; and to identify effective governance approaches for marine protectedarea management. Achieving the objectives of these actions will facilitate the integration ofmarine conservation policy into macro-regional maritime spatial planning agendas for theEuropean and contiguous seas, thereby offsetting the loss of biodiversity and ecosystemservices in this region.
Research Ideas and Outcomes

hal-01474085
https://hal-univ-perp.archives-ouvertes.fr/hal-01474085
https://hal-univ-perp.archives-ouvertes.fr/hal-01474085/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01474085/file/RIO_article_11884.pdf
DOI : 10.3897/rio.3.e11884

Éditeur(s) : HAL CCSD Springer-Verlag
Résumé : The seismology is the most effective method to explore the Structure of subduction zones to great depth. The distinguishing feature of the mantle in the subduction regions is the presence of hydrated phases, which transport water into the Earth's interior and release it with dramatic local consequences, triggering earthquakes and melting. The seismological detection of these hydrous phases and geo-dynamic interpretation of flow in the hydrous mantle depend on knowledge of the anisotropic elastic properties and the characteristics of the wave propagation in anisotropic media. In this paper we briefly recall the distinguishing features of anisotropic wave propagation and the observable parameters. We suggest the Vp/Vs ratio is a physically sound parameter than can be observed by seismology in anisotropic regions of the Earth, whereas the Poisson's ratio, which is often quoted, is not directly observable and does not correspond to the characteristics of wave propagation in an anisotropic or isotropic medium. We report for the first time the ratios of Vp/Vs1 and Vp/Vs2, where Vs1 is the fastest and Vs2 slowest S-wave velocities of an anisotropic media. We present the current knowledge of the anisotropic seismic properties of hydrous minerals in the upper mantle, transition zone, and lower mantle that are stable along low temperature geotherms associated with subduction, and identify which minerals are likely to influence seismological observations because they have very high volume fractions, or very high anisotropies, or both of these.;In the upper mantle antigorite and talc are exceptionally anisotropic (Vp 71% Vs 68% and Vp 65%, Vs 68%, respectively) and chlorite is also very anisotropic for S-waves (Vp 35%, Vs 76%). Comparatively less anisotropic are hornblende (Vp 27%, Vs 31%), used as proxy for tremolite in subduction zones, and clinohumite (21.8%, Vs 15.9%). Brucite at 4 GPa (Vp 26.5%, Vs 30.9%) and the dense hydrogen magnesium silicate (DHMS) phase A at 9GPa (Vp 9.3%, Vs 17.6%) are the only hydrous minerals stable in the upper mantle that have had their elastic properties measured at in situ mantle pressures. Except for the phase A, all these minerals are more anisotropic than olivine for at least one parameter (Vp, Vs, Vp/Vs1, or Vp/Vs2). In the transition zone the major phases hydrous wadsleyite and ringwoodite C have moderate to weak anisotropies (Vp 16.3%, Vs 16.5%, and Vp 1.9%, Vs 4.4%, respectively). The DHMS Superhydrous B has a moderate anisotropy (Vp 6.9%, Vs 11.6%). At greater depth the DHMS phase D Lit 24 GPa (Vp 10.8%, Vs 18.0%) is the only hydrous phase that can transport hydrogen from the transition zone into the lower mantle. The phase D is more anisotropic for S than P waves like many of the hydrous phases. From these data it is clear that hydrous phases are in general very anisotropic. However, pressure can play a strong role in reducing anisotropy. It is the case for brucite and talc, in which increasing pressure from ambient to 4 GPa reduces the anisotropy by about 50% for both P and S waves. In contrast, the anisotropy of the DHMS phase A does not change significantly with pressure.;Our picture of the seismic anisotropy of hydrated minerals remains incomplete; the elastic properties of many have not been measured even at ambient conditions (e.g., 10 angstrom phase and phase E) or not measured in their true elastic symmetry (e.g., clinochlore). The majority of hydrous minerals have not been measured at high pressure. and none related to hydrated mantle have been measured at elevated temperature. We have shown in the few cases where hydrous minerals have been measured as a function of pressure, that this variable has an important effect oil the velocity distribution and in most cases reduces the degree of anisotropy, hence we Would expect seismic anisotropy to play a key role in the determination of the shallow structure of subduction zones in the upper mantle.
Subduction zone geodynamics

hal-00420893
https://hal.archives-ouvertes.fr/hal-00420893

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
he search for frequent conceptual links (FCL) is a new network clustering approach that exploits both the network structure and the node properties. While recent works have been focused on the optimisation of the FCL extraction, no study has been conducted on the matching or the intersections between the conceptual links and the classical clustering approach which consists in extracting communities. In this paper, we focus on these two approaches. Our objective is to evaluate the possible relationships existing between FCL and communities to understand how the patterns obtained by each kind of methods may match as well as the useful knowledge resulting from the intersections of these two kinds of knowledge. For this purpose, we propose a set of original measures, based on the notion of homogeneity, assessing the level of shared information between these patterns when they are extracted from the same dataset. The measures are applied on three datasets and demonstrate the importance of considering simultaneously various kinds of knowledge and their intersections.
ISSN: 1869-5450

hal-01312313
https://hal.archives-ouvertes.fr/hal-01312313
DOI : 10.1007/s13278-014-0197-1

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Mussels of the subfamily Bathymodiolinae thrive around chimneys emitting hot fluids at deep sea hydrothermal vents, as well as at cold seeps and on sunken organic debris (sunken wood, whale falls). Despite the absence of light-driven primary production in these deep-sea ecosystems, mussels succeed reaching high biomasses in these harsh conditions thanks to chemosynthetic, carbon-fixing bacterial symbionts located in their gill tissue. Since the discovery of mussel symbioses about three decades ago our knowledge has increased, yet new findings are published regularly regarding their diversity, role and evolution. This article attempts to summarize current knowledge about symbiosis in Bathymodiolinae, focusing on mussel species for which information is available regarding both hosts and symbionts. Moreover, new data obtained from small mussels inhabiting sunken woods around the Philippines are provided. Indeed, mussel species from organic falls remain poorly studied compared to their vent and seep relatives despite their importance for the understanding of the evolution of symbiosis in the subfamily Bathymodiolinae.
ISSN: 1631-0691

hal-00750422
https://hal.univ-antilles.fr/hal-00750422

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Because many biological processes related to the dynamics of infectious diseases are caused by complex interactions between the environment, the host(s) and the agent(s), the necessity to address the methodological implications of this inherent complexity has recently emerged in epidemiology. Most epidemiologists now acknowledge that most human infectious diseases are likely to have complex dynamics. However, this knowledge still percolates with difficulty in their statistical "modus operandi". Indeed, for the study of complex systems, the traditional first-line statistical toolbox of epidemiologists (mainly built around the Generalized Linear Model family), despite its undeniable practicality and robustness, has structural limitations deprecating its usefulness. Three major sources of complexity neglected or not taken into account by this first-line statistical toolbox and having deep statistical implications are the multi-level organization of data, the non-linear relationships between variables and the complex interactions between variables. Three promising candidates to incorporate along with traditional tools for a new first-line statistical toolbox more suitable to apprehend these sources of complexity are the generalized linear mixed models, the generalized additive models, and the structural equation models. The aforementioned methodologies have the advantage to be generalizations of GLM models and are relatively easy to implement. Their assimilation and implementation would thus be greatly facilitated for epidemiologists. More globally, this text underlines that an improved use of other methods as such described here compared to traditional ones has to be performed to better understand the complexity challenging epidemiologists every day. This is particularly true in the field of infectious diseases for which major public health challenges will have to be addressed in the coming decades.
ISSN: 1567-1348

inserm-00872354
http://www.hal.inserm.fr/inserm-00872354
http://www.hal.inserm.fr/inserm-00872354/document
http://www.hal.inserm.fr/inserm-00872354/file/main_document.pdf
DOI : 10.1016/j.meegid.2013.09.006

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
1. Our understanding of the contribution of interspecific interactions to functional diversity in nature lags behind our knowledge of spatial and temporal patterns. Although two-species mutualisms are found in all types of ecosystems, the study of their ecological influences on other community members has mostly been limited to third species, while their influence on entire communities remains largely unexplored. 2. We hypothesized that mutualistic interactions between two respective ant species and an epiphyte mediate the biological traits composition of entire invertebrate communities that use the same host plant, thereby affecting food webs and functional diversity at the community level. 3. Aechmea mertensii (Bromeliaceae) is both a phytotelm ('plant-held water') and an ant-garden epiphyte. We sampled 111 bromeliads (111 aquatic invertebrate communities) associated with either the ant Pachycondyla goeldii or Camponotus femoratus. The relationships between ants, bromeliads and invertebrate abundance data were examined using a redundancy analysis. Biological traits information for invertebrates was structured using a fuzzy-coding technique, and a co-inertia analysis between traits and abundance data was used to interpret functional differences in bromeliad ecosystems. 4. The vegetative traits of A. mertensii depended on seed dispersion by C. femoratus and P. goeldii along a gradient of local conditions. The ant partner selected sets of invertebrates with traits that were best adapted to the bromeliads' morphology, and so the composition of the biological traits of invertebrate phytotelm communities depends on the identity of the ant partner. Biological traits suggest a bottom-up control of community structure in C. fenaoratus-associated phytotelmata and a greater structuring role for predatory invertebrates in P. goeldii-associated plants. 5. This study presents new information showing that two-species mutualisms affect the functional diversity of a much wider range of organisms. Most biological systems form complex networks where nodes (e.g. species) are more or less closely linked to each other, either directly or indirectly, through intermediate nodes. Our observations provide community-level information about biological interactions and functional diversity, and perspectives for further observations intended to examine whether large-scale changes in interacting species/community structure over broad geographical and anthropogenic gradients affect ecosystem functions.
Functional Ecology

hal-01096909
https://hal-agroparistech.archives-ouvertes.fr/hal-01096909
DOI : 10.1111/j.1365-2435-2011.01863.x