Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
UNLABELLED: During visceral leishmaniasis, the control of hepatic parasite burden is mainly due to granuloma assembly in a microenvironment consisting of both Th1 and Th2 components. Using enzyme-linked immunosorbent assay (ELISA) dosages, quantitative PCR (qPCR), immunohistochemistry, and flow cytometry, we studied the role of interleukin-33 (IL-33), a recently described cytokine signaling through the ST2 receptor, during visceral leishmaniasis. We showed that a higher level of IL-33 was detected in the serum of patients with visceral leishmaniasis than in that from healthy donors and demonstrated the presence of IL-33(+) cells in a liver biopsy specimen from a patient. Similarly, in BALB/c mice experimentally infected with L. donovani, a higher level of IL-33 was detected in the serum, as well as the presence of IL-33(+) cells and ST2(+) cells in the mouse liver. In ST2(-/-) BALB/c mice, better control of the hepatic parasite burden and reduced hepatomegaly were observed. This was associated with strong induction of Th1 cytokines (gamma interferon [IFN-γ] and IL-12) compared to the level in wild-type (WT) mice and better recruitment of myeloid cells associated with strongly induced chemokines (CCL2 and CXCL2) and receptors (CCR2 and CXCR2). Conversely, BALB/c mice treated twice weekly with recombinant IL-33 showed a dramatically reduced induction of Th1 cytokines and delayed inhibition of monocyte and neutrophil recruitment in the liver, which was associated with reduced KC/CXCL1 and CXCR2 expression. Taken together, our results suggest that IL-33 could be a new deleterious regulator of the hepatic immune response against Leishmania donovani, via the repression of the Th1 response and myeloid cell recruitment. IMPORTANCE: Visceral leishmaniasis is a life-threatening systemic disease due to the Leishmania protozoa L. infantum and L. donovani and is ranked by the World Health Organization as the second most important protozoan parasitic disease after malaria for its grave morbidity, high mortality, and global distribution. Leishmania parasites subvert the host's immune response to propagate to target organs, including the spleen, the bone marrow, and the liver. Control of hepatic parasite burdens depends on a delicate and poorly understood Th1/Th2 immune balance. To better understand this complex immune response, new cytokines are interesting targets for research studies. IL-33 is a newly described cytokine usually associated with Th2 response and involved in different diseases, including infectious diseases and hepatitis. Our results suggest that IL-33 could be a new factor of susceptibility and a potential prognostic marker during visceral leishmaniasis.
ISSN: 2150-7511

inserm-00871493
http://www.hal.inserm.fr/inserm-00871493
http://www.hal.inserm.fr/inserm-00871493/document
http://www.hal.inserm.fr/inserm-00871493/file/mBio.00383-13.pdf
DOI : 10.1128/mBio.00383-13

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
The spatio‐temporal dynamics of disease spread provide an area of acute scientific interest but substantial analytic challenges. Analytic approaches need to draw from current knowledge of disease systems yet be flexible enough to provide targeted inference without restrictive assumptions. We explore this balance in detail with respect to the observed pattern of spread of sugarcane yellow leaf virus, the causal agent of yellow leaf disease. This disease affects cultivated sugarcane plants and spreads via an aphid vector (Melanaphis sacchari). The system is of considerable economic interest, but presents several analytic complications. First, the plants begin as well separated individuals that grow into large plants with overlapping leaf canopies enabling increased vector access between neighbouring plants. The overlap between neighbouring plants first occurs within rows and then extends between rows, presenting another interesting spatial component to consider when modelling the propagation of infection. Second, the vector initially flies between plants but at some point sheds wings and shifts to walking between plants. We are particularly interested in how these two features of the system and their interrelation may impact the spatial spread of disease over time. In addition, we also explore the impact of potential immigration of infected vectors from outside of the study area. We treat our observed cane field as a spatial grid with regular spacing between rows and smaller spacing within rows. Our data consist of observed disease status of each of 1643 plants at each of six time points. We provide descriptive summaries of the temporal evolution of spatial pattern in infection, then propose hierarchical models to describe the pattern and capture the influence of the ecological and environmental factors listed above.
ISSN: 0143-9782

hal-00684235
https://hal.archives-ouvertes.fr/hal-00684235

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Deciphering the evolutionary processes driving nucleotide variation in multiallelic genes is limited by the number of genetic systems in which such genes occur. The complementary sex determiner (csd) gene in the honey bee Apis mellifera is an informative example for studying allelic diversity and the underlying evolutionary forces in a well-described model of balancing selection. Acting as the primary signal of sex determination, diploid individuals heterozygous for csd develop into females, whereas csd homozygotes are diploid males that have zero fitness. Examining 77 of the functional heterozygous csd allele pairs, we established a combinatorical criteria that provide insights into the minimum number of amino acid differences among those pairs. Given a data set of 244 csd sequences, we show that the total number of csd alleles found in A. mellifera ranges from 53 (locally) to 87 (worldwide), which is much higher than was previously reported (20). Using a coupon-collector model, we extrapolate the presence of in total 116-145 csd alleles worldwide. The hypervariable region (HVR) is of particular importance in determining csd allele specificity, and we provide for this region evidence of high evolutionary rate for length differences exceeding those of microsatellites. The proportion of amino acids driven by positive selection and the rate of nonsynonymous substitutions in the HVR-flanking regions reach values close to 1 but differ with respect to the HVR length. Using a model of csd coalescence, we identified the high originating rate of csd specificities as a major evolutionary force, leading to an origin of a novel csd allele every 400,000 years. The csd polymorphism frequencies in natural populations indicate an excess of new mutations, whereas signs of ancestral transspecies polymorphism can still be detected. This study provides a comprehensive view of the enormous diversity and the evolutionary forces shaping a multiallelic gene.
ISSN: 0737-4038

hal-01544758
https://hal.archives-ouvertes.fr/hal-01544758
DOI : 10.1093/molbev/mst207

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This paper presents Digital Image Correlation (DIC) and Infrared Thermography (IRT) methods to investigate the thermomechanical behavior of an aluminum at the microstructural scale. Electron BackScattered Diffraction (EBSD) is used to characterize the microstructure of a 3 mm thick specimen with centimetric grain size. This study combines the following imaging techniques: DIC to obtain displacement and strain fields during the test, and IRT to estimate temperature and heat source fields induced by the mechanical loading. Ultimately, the aim of this methodology is to provide energy balance during mechanical test at the scale of the microstructure, in order to propose thermomechanical con-stitutive modelling of crystalline plasticity.
ISSN: 0143-8166

hal-01287711
https://hal.archives-ouvertes.fr/hal-01287711
https://hal.archives-ouvertes.fr/hal-01287711/document
https://hal.archives-ouvertes.fr/hal-01287711/file/Local_experimental_investigations_Li_al_2016.pdf
DOI : 10.1016/j.optlaseng.2016.01.001

Éditeur(s) : Oxford Univ Press Inc
Résumé : Since the transition from terrestrial to marine environments poses strong osmoregulatory and energetic challenges, temporal and spatial fluctuations in oceanic salinity might influence salt and water balance (and hence, body condition) in marine tetrapods. We assessed the effects of salinity on three species of sea snakes studied by mark-recapture in coral-reef habitats in the Neo-Caledonian Lagoon. These three species include one fully aquatic hydrophiine (Emydocephalus annulatus), one primarily aquatic laticaudine (Laticauda laticaudata), and one frequently terrestrial laticaudine (Laticauda saintgironsi). We explored how oceanic salinity affected the snakes' body condition across various temporal and spatial scales relevant to each species' ecology, using linear mixed models and multimodel inference. Mean annual salinity exerted a consistent and negative effect on the body condition of all three snake species. The most terrestrial taxon (L. saintgironsi) was sensitive to salinity over a short temporal scale, corresponding to the duration of a typical marine foraging trip for this species. In contrast, links between oceanic salinity and body condition in the fully aquatic E. annulatus and the highly aquatic L. laticaudata were strongest at a long-term (annual) scale. The sophisticated salt-excreting systems of sea snakes allow them to exploit marine environments, but do not completely overcome the osmoregulatory challenges posed by oceanic conditions. Future studies could usefully explore such effects in other secondarily marine taxa such as seabirds, turtles, and marine mammals.
Integrative And Comparative Biology (1540-7063) (Oxford Univ Press Inc), 2012-08 , Vol. 52 , N. 2 , P. 235-244

Droits : The Author 2012. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.
http://archimer.ifremer.fr/doc/00089/20064/20739.pdf
DOI:10.1093/icb/ics081
http://archimer.ifremer.fr/doc/00089/20064/

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Las religiones de origen africano han sido tomadas en Brasil, en Cuba y más recientemente en Venezuela como instrumento para incrementar la entrada de divisas, en programas de desarrollo del turismo presentados por las autoridades como sostenibles. Pero, tanto el control ejercido sobre ellas por los organismos oficiales, con fines de comercialización, como las rivalidades entre paises, así como en algún caso, entre ciudades de un mismo país, conllevan una enajenación de la cultura (según la teoría del control cultural de Guillermo Bonfill), cuestionando la posibilidad de un desarrollo equilibrado, es decir sostenible.
Les religions d’origine africaine ont été transformées, au Brésil, à Cuba et plus récemment au Venezuela, en instruments pour augmenter la captation de devises, par le biais de programmes présentés par les autorités comme répondant aux normes du développement durable. Mais, tant le contrôle exercé sur ces manifestations culturelles, à des fins de commercialisation, que les rivalités engendrées entre pays, ou entre villes dans certains cas, mènent à une aliénation des acteurs de leur propre culture (après Guillermo Bonfill), contredisant la définition même de “développement durable”.
The religions of African origin have been taken in Brazil, in Cuba and more recently in Venezuela as instruments to increase the inflow of currency, in tourism development programs presented by the authorities as sustainable. But the control exercised on them by the State organizations, with marketing purposes, as well as the rivalries between countries, as well as between cities of the same country in some cases, carry an alienation of the culture (according to Guillermo Bonfill's theory of cultural control), questioning the possibility of a balanced development, that is to say a sustainable development.
Brésil
Cuba
Venezuela

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.3852
http://journals.openedition.org/etudescaribeennes/3852

Éditeur(s) : HAL CCSD
Résumé : International audience
The identification and economic valuation of ecosystem services (ES) are becoming important components of coral reef management. In many contexts, protection of human assets against coastal floods is one of the most important ES provided by coral reefs. The methods utilized to characterize this ES should be able to accommodate situations with low data availability, without sacrificing robustness. In this paper, we suggest such an approach that utilizes expert opinion and does not require copious amounts of data. Our primary objective is to find a balance between simple and complex models that can be used in a data scarce environment, to produce an economic valuation of the coral reef ES of protection against coastal floods. The approach has three steps: (i) identify geographic zones and assets at risk, (ii) identify the contributing role of coral reefs in the protection of coasts and, (iii) value the annual repair costs of assets through the avoided damage cost approach. The proposed method seems appropriate for advocacy with policy makers, but appears to be less effective for small scale approaches, such as those required for Payment for ES negotiations or marine spatial planning.
Ecosystem Services

hal-01359394
https://hal-univ-perp.archives-ouvertes.fr/hal-01359394
DOI : 10.1016/j.ecoser.2016.07.005

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : A preliminary version appeared in the 18th ACM-SIAM Symposium on Discrete Algorithms, pp. 746- 755, 2007
International audience
The Voronoi diagram of a finite set of objects is a fundamental geometric structure that subdivides the embedding space into regions, each region consisting of the points that are closer to a given object than to the others. We may define various variants of Voronoi diagrams depending on the class of objects, the distance function and the embedding space. In this paper, we investigate a framework for defining and building Voronoi diagrams for a broad class of distance functions called Bregman divergences. Bregman divergences include not only the traditional (squared) Euclidean distance but also various divergence measures based on entropic functions. Accordingly, Bregman Voronoi diagrams allow one to define information-theoretic Voronoi diagrams in sta- tistical parametric spaces based on the relative entropy of distributions. We define several types of Bregman diagrams, establish correspondences between those diagrams (using the Legendre transformation), and show how to compute them efficiently. We also introduce extensions of these diagrams, e.g. k-order and k-bag Bregman Voronoi diagrams, and introduce Bregman triangulations of a set of points and their connection with Bregman Voronoi diagrams. We show that these triangulations capture many of the properties of the celebrated Delaunay triangulation.
ISSN: 0179-5376

hal-00488441
https://hal.archives-ouvertes.fr/hal-00488441
https://hal.archives-ouvertes.fr/hal-00488441/document
https://hal.archives-ouvertes.fr/hal-00488441/file/BVD-DCG.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Climate models for the coming century predict rainfall reduction in the Amazonian region, including change in water availability for tropical rainforests. Here, we test the extent to which climate variables related to water regime, temperature and irradiance shape the growth trajectories of neotropical trees. . We developed a diameter growth model explicitly designed to work with asynchronous climate and growth data. Growth trajectories of 205 individual trees from 54 neotropical species censused every 2 months over a 4-year period were used to rank 9 climate variables and find the best predictive model. . About 9% of the individual variation in tree growth was imputable to the seasonal variation of climate. Relative extractable water was the main predictor and alone explained more than 60% of the climate effect on tree growth, i.e. 5.4% of the individual variation in tree growth. Furthermore, the global annual tree growth was more dependent on the diameter increment at the onset of the rain season than on the duration of dry season. . The best predictive model included 3 climate variables: relative extractable water, minimum temperature and irradiance. The root mean squared error of prediction (0.035 mm.d(-1)) was slightly above the mean value of the growth (0.026 mm.d(-1)). . Amongst climate variables, we highlight the predominant role of water availability in determining seasonal variation in tree growth of neotropical forest trees and the need to include these relationships in forest simulators to test, in silico, the impact of different climate scenarios on the future dynamics of the rainforest.
ISSN: 1932-6203

hal-01268350
https://hal.archives-ouvertes.fr/hal-01268350
DOI : 10.1371/journal.pone.0034074
PRODINRA : 215438
PUBMED : 22506012

Éditeur(s) : Neidine editeurs
Résumé : The publication draws up a balance sheet about the natural marine assets of New Caledonia by distinguishing the coast and the intertidal zones, the coral reefs and lagoons, the open sea or "deep blue". A set of assets relative to the living and mineral natural resources, to the characteristics of the shallow and deep marine biodiversity, to the potential marine energy resources are discussed. This publication, edited in a Consumer directed free magazine, draws up a set of perspectives relative to a blue economy to be built in a country still very centred on its ground resources, essentially the nickel mining industry.
Le dossier dresse un bilan des atouts naturels de la nouvelle-Calédonie en matière marine en distinguant le littoral et l'intertidal, les récifs et lagons, la mer ouverte ou "grand bleu". Sont discutés un ensemble d'atouts relatifs aux ressources naturelles vivantes et minérales, aux caractéristiques de la biodiversité marine peu profonde et semi profonde, aux ressources énergétiques potentielles.Cette publication, éditée dans une revue orientée Grand Public, dresse un ensemble de perspectives relatives à une économie bleue à construire dans un pays encore très axé sur ses ressources terrestres, essentiellement l'industrie minière de nickel.
Taï Kona (2269-7535) (Neidine editeurs), 2013-03 , N. 1 , P. 12-25

Droits : Tai Kona
http://archimer.ifremer.fr/doc/00142/25350/23432.pdf
http://archimer.ifremer.fr/doc/00142/25350/

Éditeur(s) : HAL CCSD
Résumé : International audience
The INTERREG Caribbean IV program recommends the valorization and protection of the region's environmental core, through collaborative and sustainable management of resources. It uses Martinique as the test case. The French territories of Saint-Martin, Saint-Barthélemy, Guadeloupe, and Martinique, and the member states of the Organization of Eastern Caribbean States are part of a geographic continuum that can easily be identified through its similar landscapes, climates, and natural resources and also through the environmental degradation the states have to face, caused by human activity (pollution and deterioration of ecosystems and habitats), natural hazards, and climate change including sea level rise. Therefore the islands of the Lesser Antilles are faced with an important developmental and environmental challenge, which could be easily summarized as a struggle for balance.
Meteorological Technology International

ird-00742661
http://hal.ird.fr/ird-00742661
http://hal.ird.fr/ird-00742661/document
IRD : fdi:010057442

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
This study investigates three-dimensional flow modes of orogenic plateaus by means of physical modeling. Experiments consist of shortening two contiguous lithospheres of contrasting strength, one being a weak plateau-type lithosphere and the other a strong craton-type lithosphere. The lateral boundaries are either totally confined or allow escape toward a lateral foreland on one side. Two synconvergence flow regimes are distinguished, which are governed by the balance between the gravity potential and the strength of the plateau crust and the resistance of its lateral foreland. The first regime implies transversal (orogen-normal) injection of plateau lower crust into the collision zone as a result of confinement of the plateau by an increasingly stiffer lateral boundary. As a precursor mechanism to channel flow, transversal injection responds to downward thickening of the plateau crust that is forcedly extruded into the orogenic wedge. The second regime is that of collapse-driven lateral escape of the plateau. This regime is established after a threshold is attained in the interplate coupling in the collision zone, which allows the gravity potential of the plateau to overcome the resistance of its lateral boundary. Under the collapse-driven escape regime (orogen parallel), such as that governing Tibet during the last 13 Ma, most of the convergence in the plateau and the top and rear of the collisional wedge is transformed into lateral flow and extension.
ISSN: 0148-0227

hal-01229107
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/file/2015JB012110_revised.pdf
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01229107/file/SupplementaryMaterial_final.pdf

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
The effect of trace concentrations of Ti on the rate and mechanism of hydrogen diffusion in pure forsterite was investigated experimentally. Forsterite doped with 350–400 ppm Ti (predominantly octahedral Ti3+, minor tetrahedral Ti4+) was prepared by diffusing Ti into pure synthetic forsterite at high temperature (1500 °C), very low oxygen fugacity (~QFM-5) at atmospheric pressure. The Ti-doped forsterite was then diffusively hydroxylated in a piston-cylinder apparatus at much lower temperatures (650–1000 °C) and higher oxygen fugacities, at 1.5–2.5 GPa, with chemical activities buffered by forsterite-enstatite or forsterite-periclase and partial pressure of H2O equal to total pressure. This produced hydrogen concentration-distance profiles of several hundred micrometers in length. Diffusion of hydrogen through the Ti-doped forsterite, even at very high Embedded Image , does not lead to redox re-equilibration of the high Ti3+/ΣTi ratio set during the synthesis of the starting material at extremely reducing conditions—the metastable point defects are partially preserved.Three main hydroxylated point defects are observed; hydroxyl is associated with Ti4+ (titano-clinohumite point defects), Ti3+ (and possibly other trivalent cations), and M-site vacancies. Concentration-distance profiles represent an interplay between diffusion and reaction (i.e., site rearrangement) to form the observed point defects. In all experiments, the concentration-distance profiles of the hydroxylated Ti defects coincide with the concentration-distance profiles of the M-site vacancy substitution, with the same crystallographic anisotropy. This suggests that the macroscopic movement of hydrogen through the crystal is due to one diffusion mechanism (the diffusion of hydroxylated M-site vacancies). The net H diffusion coefficient [logD(ΣH)], between 650–1000 °C, is Embedded Image where the values of logD0(ΣH) parallel to [100] and [001] directions are −3.0 ± 0.4 and −2.2 ± 0.4, respectively; diffusion is therefore around one order of magnitude faster along the c axis than along the a axis. The diffusion of hydrogen is slightly faster in Ti-doped forsterite than in pure forsterite. There is no effect of chemical activity or oxygen fugacity on the rate of diffusion. Hydrogen diffusion profiles represent a complex interplay between the movement of H through the crystal lattice and point-defect reactions to maintain charge balance.
ISSN: 0003-004X

hal-01467402
https://hal.archives-ouvertes.fr/hal-01467402
DOI : 10.2138/am-2016-55681571

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : En Indonésie orientale, entre l’île de Sumbawa et celle de Florès, se trouve le parc national de Komodo, du nom de la principale île habitée par les fameux varans, un superbe espace naturel désormais préservé par l’UNESCO et entouré de récifs coralliens. Quelques familles de pêcheurs, la plupart musulmans, peuplent ce petit archipel aujourd’hui prisé par les touristes internationaux pour ses dragons et ses lagons. En réalité, les varans géants de Komodo ne sont pas les derniers témoins de la préhistoire, mais d’énormes lézards, impressionnants, très photogéniques et parfois dangereux.Un endroit idéal pour s’adonner à une forme singulière de tourisme d’aventure, même s’il est aujourd’hui plus de masse que de niche. Entre une plage balnéaire et une balade en mini croisière, quelques dizaines de milliers de touristes annuels viennent approcher ces drôles de dragons qui effraient autant qu’ils fascinent les visiteurs. Aussi, promeneurs, baigneurs et excursionnistes se croisent — le temps d’un frisson bien encadré, il est vrai dans un décor de rêve — dans ce parc national, tous animés par les mêmes volontés et curiosité de « voir pour de vrai » cette créature étrange qui stimule notre imaginaire rempli de dinosaures.
In eastern Indonesia, between the island of Sumbawa and Flores that, is the Komodo National Park, named after the main island where the famous lizards are found, a beautiful natural area now protected by UNESCO and surrounded by reefs coral. Some families of fishermen, most Muslims inhabit this small archipelago prized today by international tourists for its dragons and lagoons. In reality, the giant Komodo dragons are the last witnesses of prehistory but huge lizards, impressive, photogenic and sometimes dangerous.An ideal place to indulge in a singular form of adventure tourism, although it is now more mass than niche. Between a seaside beach and a leisurely mini cruise, tens of thousands of annual tourists come to approach these funny dragons that scare as they fascinate visitors. Also, walkers, swimmers and hikers cross - time for a well supported thrill, it is true in a dream setting - in this national park, all driven by the same desire and curiosity to "see for real" this creature strange that stimulates our imagination filled with dinosaurs.
Indonésie
Komodo
Bali

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.7577
http://journals.openedition.org/etudescaribeennes/7577

Éditeur(s) : Neidine Editeurs
Résumé : This article first draws up a balance sheet of all various implemented techniques to observe and monitor the shallow marine biodiversity. Then the article focuses on the techniques of the rotating high resolution submarine video and their implementation in New Caledonia on various sites and habitats under various management / protection policies such as Marines Protected Areas, strict marine reserves, registered sites on UNESCO world heritage or free access zones. An evaluation of these techniques and of their contributions is proposed in terms of transfer to other geographical zones, of practical feasibility in the technical, logistic and cost point of view as also are analyzed the perspectives offered by those technologies in terms of innovation, of support for the management or as communication tool on the health of the observed biodiversity.
Cet article dresse tout d’abord un bilan des différentes techniques mises en oeuvre pour observer et suivre la biodiversité marine peu profonde. Ensuite l’article se focalise sur les techniques de la vidéo sous marine rotative de haute définition et leur mise en œuvre en Nouvelle-Calédonie sur différents sites et habitats soumis ou non à des règles de gestion/protection tels que des Aires Marines Protégées, des réserves intégrales ou des sites inscrits au patrimoine mondial. Une évaluation de ces techniques et de leur apports est proposée en termes de transfert à d’autres zones géographiques, de faisabilité pratique aux plans techniques, logistiques et de coût comme également sont analysées les perspectives en termes d’innovation, d’appui à la gestion ou encore d’outil de communication sur les états de la biodiversité observée.
Tai Kona (2269-7535) (Neidine Editeurs), 2014-01 , N. 6 , P. 12-26

Droits : Tai Kona
http://archimer.ifremer.fr/doc/00174/28506/26855.pdf
http://archimer.ifremer.fr/doc/00174/28506/

Éditeur(s) : HAL CCSD
Résumé : International audience
It is an admitted fact that mainstream boosting algorithms like AdaBoost do not perform well to estimate class conditional probabilities. In this paper, we analyze, in the light of this problem, a recent algorithm, unn, which leverages nearest neighbors while minimizing a convex loss. Our contribution is threefold. First, we show that there exists a subclass of surrogate losses, elsewhere called balanced, whose minimization brings simple and statistically efficient estimators for Bayes posteriors. Second, we show explicit convergence rates towards these estimators for unn, for any such surrogate loss, under a Weak Learning Assumption which parallels that of classical boosting results. Third and last, we provide experiments and comparisons on synthetic and real datasets, including the challenging SUN computer vision database. Results clearly display that boosting nearest neighbors may provide highly accurate estimators, sometimes more than a hundred times more accurate than those of other contenders like support vector machines.
European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML PKDD)
Bristol, United Kingdom

hal-00702771
https://hal.archives-ouvertes.fr/hal-00702771
https://hal.archives-ouvertes.fr/hal-00702771/document
https://hal.archives-ouvertes.fr/hal-00702771/file/ecml12-dnbnb-sub.pdf

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Le milieu marin de la Mer des Caraïbes est composé de trois écosystèmes principaux : les récifs coralliens, les mangroves et les herbiers, qui abritent une faune et une flore exceptionnelles. Mais l’équilibre fragile de ces espaces est menacé par les nombreuses activités humaines qui les dégradent progressivement. Face aux enjeux socio-économiques qu’ils représentent pour les pays caribéens, ces derniers ont établi un cadre juridique à l’échelle régionale pour la protection et la gestion de leur ressource marine, la Convention de Carthagène. Après avoir dressé un tableau de la situation environnementale des principaux écosystèmes marins caribéens, il convient de faire un point sur les modes de gestion mis en œuvre pour les préserver.
The marine environment of the Caribbean Sea is composed primarily of three main ecosystems: coral reefs, mangroves and seagrasses, home to fauna and flora. But the delicate balance of these areas is threatened by many human activities that deteriorate gradually deteriorated them. Deal with socio-economic issues around these resources, Caribbean countries have established a legal framework at the regional level to ensure the protection and management of marine resources (the Cartagena Convention). After drawing up an overview of the environmental situation of the main Caribbean marine ecosystems, it should present the management mode adopted to preserve them.
Caraïbes

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.4343
http://journals.openedition.org/etudescaribeennes/4343

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Reef positions record the interaction between eustasy and tectonics, and have been used worldwide to characterize vertical deformations of upper-plates at different time-scales and constrain the seismic behavior of megathrusts. Along the Lesser Antilles volcanic arc, high-resolution marine geophysical data were collected on the 2–20 km wide eastern Martinique reef platform to reconstruct its stratigraphic and morphologic history, and understand the influence of local normal faulting, volcanism and plate-scale subduction processes on Holocene and Late Pleistocene reef development. The subsiding Martinique platform's stratigraphy is composed of multiple superimposed sea-level highstand deposits separated by subaerial exposure surfaces of sea-level low stands. The carbonate platform consists of two laterally-extensive carbonate units (unit U2 overlying unit U3) that extend to the platform edge to a depth of − 95 m MSL (mean sea level), and form two morphologic terraces, M2 and M3 respectively. The landward portion of unit U2 is partially overlain between 0 and − 60 m MSL by the living reef tract U1. The current reef is composed of a landward fringing reef, a lagoon and a seaward barrier reef, the latter forming a double-bank barrier around the Caravelle Peninsula. In near-shore multi-channel seismic profiles, a distinct reflector at ~− 35 m MSL, probably a subaerial exposure surface E1, separates the reef sequence formed during the last transgression from a Pleistocene fossil reef tract forming unit U2. Offshore of Mount Pelée volcano (Late Pleistocene), the Holocene reef did not develop above unit U2, whose upper surface is incised by channels and apparent sinkholes. During the Holocene transgression, the possibility of excessive turbidity due to volcanic activity may have inhibited reef development in this area. The un-dated unit U2 probably developed 120–130 ka ago during the last interglacial (MIS 5.5) + 6 m MSL highstand as thick, extensive reefs deposited all along the Lesser Antilles arc. Due to subsidence, MIS 5.5 reefs are not represented by onshore facies, except along the southern Sainte Anne Peninsula where normal faulting and uplift balances island-scale subsidence. Based on unit U2's present elevation and assuming an MIS 5.5 age and + 6 m MSL sea level, Martinique has subsided at maximum 0.3 m/ky, likely due to subduction processes that question the coupling state of the megathrust.
ISSN: 0025-3227

hal-01307036
https://hal.archives-ouvertes.fr/hal-01307036
DOI : 10.1016/j.margeo.2015.08.001

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Yearly monitoring in one of the most affected coastal zones by the Prestige oil spill, namely Nemiña and O Rostro beaches (NW Spain), has been carried out since 2004. Topographic data of beaches revealed seasonal altimetric changes up to 4 m that would prevent the on shore persistence of oil. However, surficial and subsurficial oil was detected in the intertidal area of both beaches in all campaigns. The hydrocarbon analysis confirmed that this oil corresponded to the Prestige oil, even nine years after the accident. Tar balls were highly biodegraded suggesting that the oil was accumulated on the subtidal sediments for a long time and transported to the coast by the action of waves. The present work provides new evidence of the long term persistence of deep oil spills from wrecks in marine areas where the hydrodynamic conditions play a twofold key role, in determining the exposed coastal area to recurrent contamination and in burying and resurfacing the oil in the intertidal zone.
ISSN: 0304-3894

hal-01071707
https://hal.archives-ouvertes.fr/hal-01071707
DOI : 10.1016/j.jhazmat.2013.01.057

Éditeur(s) : HAL CCSD Wiley
Résumé : Sodium, an element which is needed by animals but often toxic in high concentrations to plants, may be deficient and limit animal abundance in inland continental regions, but may be overabundant and limit plant productivity in coastal regions. Here we present data from 50 independent plots (including leaf data from more than 2480 individual trees) showing that leaves in the Amazon basin uptake high amounts of sodium (Na) in a manner more similar to the essential cation potassium (K) than to the toxic cation aluminium (Al). Leaf Na increases linearly with soil Na concentrations, and there is no apparent mechanism for selective exclusion of Na in comparison to K, a key attribute of halophytes. This indicates that the Amazon basin is broadly non-halophytic and increased sodium concentrations in non-halophyte plants often decrease plant productivity. Total Na concentrations are approximate to 10 times higher in coastal regions than inland regions. Such concentration gradients in nutrients may have been reduced in the past because large animals that were abundant in the Pleistocene have been hypothesized to play a large role in reducing nutrient concentration gradients at continental scales. We use a diffusion model and a Na loss rate based on empirical data to estimate that large animals may have moved significant quantities of Na inland away from coastal regions in the Amazon Basin. Therefore, our simple model suggests that large animals may play an important, yet diminishing, role in maintaining the sodium balance of the planet.
ISSN: 0906-7590

hal-01531615
https://hal.archives-ouvertes.fr/hal-01531615
PRODINRA : 349612
DOI : 10.1111/ecog.01589