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International audience; Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasinglyconsidered potential competitors, especially since recent local declines in harbourseal numbers while grey seal numbers remained stable or increased at their Europeancore distributions. A better understanding of the interactions between these speciesis critical for conservation efforts. This study aimed to identify the trophic nicheoverlap between harbour and grey seals at the southern limit of their Europeanrange, in the Baie de Somme (BDS, Eastern English Channel, France), where numbersof resident harbour seals and visiting grey seals are increasing exponentially. Dietaryoverlap was identified from scat contents using hierarchical clustering. Isotopic nicheoverlap was quantified using δ13C and δ15N isotopic values from whiskers of 18 individuals,by estimating isotopic standard ellipses with a novel hierarchical modeldeveloped in a Bayesian framework to consider both intraindividual variability andinterindividual variability. Foraging areas of these individuals were identified fromtelemetry data. The three independent approaches provided converging results, revealinga high trophic niche overlap due to consumption of benthic flatfish. Two dietclusters were dominated by either small or large benthic flatfish; these comprised85.5% [CI95%: 80.3%–90.2%]of harbour seal scats and 46.8% [35.1%–58.4%]of greyseal scats. The narrower isotopic niche of harbour seals was nested within that ofgrey seals (58.2% [22.7%–100%]overlap). Grey seals with isotopic values similar toharbour seals foraged in coastal waters close to the BDS alike harbour seals did, suggestingthe niche overlap may be due to individual grey seal strategies. Our findingstherefore provide the basis for potential competition between both species (foragingon benthic flatfish close to the BDS). We suggest that a continued increase in sealnumbers and/or a decrease in flatfish supply in this area could cause/amplify competitiveinteractions and have deleterious effects on harbour seal colonies.

Natural Environment Research Council (GrantNumber(s): SMRU1001; Grant recipient(s): Ailsa Hall) 1. In the United Kingdom (UK), several harbour seal (Phoca vitulina) populations have been declining over the past decade. In order to understand the effect of these changes in abundance, this study seeks to determine the population structure of harbour seals in the UK, and in Scotland in particular, on a wider and finer spatial scale than has previously been reported. 2. Harbour seals were genotyped from 18 different localities throughout the UK and neighbouring localities in mainland Europe, at 12 microsatellite loci. Results from Bayesian and frequency based tests of population structure suggested an initial structural division into two main groups consisting of localities in northern UK and southern UK-mainland Europe, respectively. 3. These two clusters were further divided into four geographically distinct genetic clusters. 4. An overall agreement between the genetic results and the existing management areas for UK harbour seals was observed, but it is also clear that an adaptive management approach should be adopted, in which the delineation of the current management areas is maintained until further genetic and ecological information has been accumulated and analysed. Publisher PDF

International audience

International audience; Shipping noise is a threat to marine wildlife. Grey seals are benthic foragers, and thus experience acoustic noise throughout the water column, which makes them a good model species for a case study of the potential impacts of shipping noise. We used ship track data from the Celtic Sea, seal track data and a coupled ocean-acoustic modelling system to assess the noise exposure of grey seals along their tracks. It was found that the animals experience step changes in sound levels up to ~20dB at a frequency of 125Hz, and ~10dB on average over 10 1000Hz when they dive through the thermocline, particularly during summer. Our results showed large seasonal differences in the noise level experienced by the seals. These results reveal the actual noise exposure by the animals and could help in marine spatial planning. 2

International audience; The current information systems manage several, different and huge databases. The data can be temporal, spatial and other application domains with specific knowledge. For these reasons, new approaches must be designed to fully exploit data expressiveness and heterogeneity taking into account application's needs. As part of ontology-based information system design, this paper proposes an ontology modeling approach. After introducing the theoretical modeling's part, we give an implementation based on real trajectory data. We also discuss some issues related to the computation complexity.

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International audience; L'évolution des systèmes de capture des données concernant les objets mobiles a donné naissance à de nouvelles générations d'applications dans différents domaines. Les données capturées, communément appelées "trajectoires", sont au coeur des applications qui analysent et supervisent le trafic routier, maritime et aérien ou également celles qui optimisent le transport public. Elles sont aussi exploitées dans les domaines du jeu vidéo, le cinéma ou le sport par les systèmes de capture des mouvements. Dans cet article, nous présentons un travail issu d'une collaboration avec une équipe de recherche qui s'intéresse à l'analyse et la compréhension des comportements des mammifères marins dans leur milieu naturel. On présente quelques requêtes qui intéressent les experts du domaine qui montrent l'impossibilité d'exploiter les trajectoires dans leurs états bruts. En effet, l'analyse de ces requêtes fait ressortir trois types de composantes sémantiques : thématique, spatiale et temporelle. Ces composantes doivent être rattachées aux données des trajectoires ce qui conduit à introduire un processus d'annotation qui transforme les trajectoires brutes en trajectoires sémantiques. Pour exploiter les trajectoires sémantiques, on construit une ontologie du domaine qui modélise les données brutes et leurs annotations à travers des règles métiers. L'ontologie du domaine est reliée à des ontologies spatiales et temporelles. Cette intégration nous permet d'envisager des requêtes nécessitant un raisonnement complet combinant à la fois des concepts du domaine et d'autres en relation avec le temps ou l'espace. Enfin, cet article présente la difficulté de mise en oeuvre sur des données de taille réelles (des centaines de milliers d'individus) lors du raisonnement à travers les mécanismes d'inférence utilisant des règles métiers.

lien internet : http://www.scirp.org/journal/ojcm/; International audience; Thermal dissipation in power electronic devices can be improved through the elaboration of a new generation of layered heat sinks based on copper (Cu) -carbon nanofibers (CNF) composites. Though the high theoretical thermal conductivity of CNF (1200 W/m.K) no Cu-CNF composites with enhanced thermal properties are available. Indeed conventional compositing processes do not allow neither a good dispersion of the nano-reinforcements nor a control of the nanofiber-matrix interface which is not suitable for efficient heat transfers. In this paper, a process based on CNF coating with Cu followed by uniaxial hot pressing in described. It is shown that under proper experimental conditions the salt decomposition coating method is capable of achieving the desired high thermal conductivity values (> 400 W/m.K) thanks to a good dispersion of the CNF, low porosity content and the control of Cu-CNF interfaces.

Cu/CNF (Carbon Nano Fiber) composite materials can be used as heat sink in power electronic devices. They can substitute Copper by combining a high thermal conductivity and a coefficient of thermal expansion close to the printed circuit one (alumina or aluminum nitride). After studying the properties of Copper matrix and CNF, three methods were set up for the elaboration of the Cu/CNF composite materials. It was first synthesized by a simple powder metallurgy process. Second, in order to obtain a better homogeneity, CNF were individually coated with Cu by an electroless deposition method. Third, an original technique involving the decomposition of a metallic salt has been used. Measurements of the density, the thermal properties (conductivity and dilatation), and the characterization of the microstructure of the composite materials have been performed. It reveals the complexity of the realization of such a composite. Indeed, the dispersion of CNF and the chemical nature of the Cu/CNF interfaces have to be controlled in order to reach the desired thermal properties. Analytical and numerical simulations have been conducted and correlated with the experimental results to predict final properties of our materials.; Le matériau composite Cu/NFC (Nano Fibre de Carbone) peut être utilisé en tant que drain thermique par les industriels de l'électronique de puissance. En remplacement du cuivre, il doit combiner une conductivité thermique élevée et un coefficient de dilatation thermique adapté à celui de la céramique du circuit imprimé (alumine ou nitrure d'aluminium). Après avoir étudié les propriétés de la matrice cuivre et des NFC, plusieurs méthodes de synthèse du composite Cu/NFC ont été développées. Le composite a tout d'abord été élaboré par métallurgie des poudres. Puis, dans le but d'améliorer l'homogénéité, il a été envisagé de revêtir individuellement chaque NFC par du cuivre déposé par voie chimique electroless ainsi que par une méthode originale de décomposition d'un sel métallique. Des mesures de densité et de propriétés thermiques (conductivité et dilatation) ainsi que les caractérisations microstructurales de ces matériaux montrent la complexité de l'élaboration d'un tel composite. En effet, la dispersion des nanofibres, la nature des interfaces fibres/matrice et surtout les phénomènes thermiques à l'échelle nanométrique sont autant de paramètres à contrôler afin d'obtenir les propriétés recherchées. La simulation numérique et analytique, qui a été mise en oeuvre en parallèle a été corrélée aux résultats expérimentaux, afin de prédire les propriétés finales de nos matériaux.

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