Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
An automated assay of anti-P1 allohemagglutinins has been carried out on 133 P2 subjects: 13 with acute hepatic distomiasis (Fascioliasis), 20 with hydatidosis and 100 healthy blood donors. Anti-P1 were detected in 100% of the distomatid sera, in 50% of the hydatid and in 29% of the healthy individuals. When compared to a reference serum test (anti-P1 standard), their concentration was found to be weak in healthy subjects, moderate in hydatidosis and exceptionally increased in acute distomiasis (up to 5-6 times the standard anti-P1 level). The 2-mercaptoethanol treatment showed that even the increased distomatid anti-P1 sera were of an IgM nature. The respective origin, synthesis and strength of these allohemagglutinins are discussed and the advantages of using distomatid IgM anti-P1 as human sera test are emphasized.
ISSN: 0042-9007

hal-00715441
https://hal.univ-antilles.fr/hal-00715441
PUBMED : 7385756

Éditeur(s) : HAL CCSD Springer/Terra Scientific Publishing Company
Résumé : International audience
We carried out a detailed paleomagnetic, rock-magnetic, and Thellier paleointensity study of all similar to 3.6 My Pliocene lava flow succession in southern Georgia. An earlier study (Camps et al., 1996) revealed that several consecutive lava flows record an intermediate polarity direction at the base of the section followed by a thick reverse polarity zone. The transitional field was interpreted as an excursion within chron 2Ar or all upper Cochiti-Gilbert reversal. New paleomagnetic data reported here have been obtained from nearby lava successions. In total, about 170 standard paleomagnetic cores belonging to 22 lava flows were collected during the 2005 sample collection campaign. Rock-magnetic experiments showed that the remanence is carried by Ti-poor titanomagnetite in most of the samples. The fraction of grains with multidomain magnetic structure does not seem to be important. Characteristic remanent magnetization was successfully determined oil all samples. The direct correlation with the original (Thoki) sequence, previous preliminary measurements of natural remanent magnetization (Sologashvili, 1986), and field observations allowed us to establish a new magnetic stratigraphy. The lower part of section is characterized by intermediate magnetic polarity followed by thick reversely magnetized lavas. The upper sequence, represented by 18 consecutive flows yielded normal magnetic polarity. The mean paleointensity of the intermediate field is drastically reduced with respect to the post-transitional field strength. Based on all available radiometric ages and new paleomagnetic data, it may be speculated that Gilbert-Gauss (R-N) reversal was recorded at the upper part of sequence. Lower intermediate polarity flows possibly represent a form of precursor of this reversal that is similar to the Matuyama-Brunhes geomagnetic transition.
ISSN: 1343-8832

hal-00413099
https://hal.archives-ouvertes.fr/hal-00413099

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
The elucidation of relationships between biodiversity and ecosystem processes has been limited by the definition of metrics of biodiversity and their integration into experimental design. Functional trait screening can strengthen the performance of these designs.* We suggest the use of Rao's quadratic entropy to measure both functional diversity and phylogenetic diversity of species mixtures proposed for an experimental design, and demonstrate how they can provide complementary information.* We also present an index assessing the statistical performance of these independent variables in different experimental designs. Measurement of independent variables as continuous vs. discrete variables reduces statistical performance, but improves the model by quantifying species differences masked by group assignments.* To illustrate these advances, we present an example from a tropical forest tree community in which we screened 38 species for nine functional traits. The proposed TropiDEP design is based on the relative orthogonality of two multivariate trait axes defined using principal component analysis.* We propose that independent variables describing functional diversity might be grouped to calculate independent variables describing suites of different traits with potentially different effects on particular ecosystem processes. In other systems these axes may differ from those reported here, yet the methods of analysis integrating functional and phylogenetic diversity into experimental design could be universal.
La compréhension des relations pouvant exister entre biodiversité et fonctionnement des écosystèmes a été longtemps limitée par la définition de méthodes de quantification de la diversité biologique et la mise en œuvre de dispositifs expérimentaux permettant sa mesure. L'identification de syndromes de traits fonctionnels clefs influençant des fonctions écosystémiques particulières peut renforcer la performance de ces dispositifs.* Nous suggérons l'utilisation de l'entropie quadratique de Rao pour mesurer la diversité fonctionnelle et phylogénétique dans des assemblages synthétiques d'espèces, et montrons comment ces mesures de diversité sont complémentaires.* Nous présentons également un indice permettant de tester la performance statistique de ces variables indépendantes dans différents modèles expérimentaux. L'utilisation de variables indépendantes continues plutôt que discrètes réduit la performance statistique mais améliore le modèle en quantifiant les différences fonctionnelles entre espèces; différences généralement masquées lors de leur assignation en groupes fonctionnels.* Pour illustrer ces avancées, nous présentons un exemple d'assemblages synthétiques à partir de 38 espèces d'arbres de forêt tropicale sélectionnées pour 9 traits fonctionnels (TropiDEP). Le plan d'expérience de TropiDEP est basé sur l'orthogonalité relative de deux axes multivariés de traits fonctionnels définis par analyse en composantes principales.* Nous proposons que les variables décrivant la diversité fonctionnelle soient groupées pour calculer des variables indépendantes, divisées en plusieurs axes décrivant des combinaisons de différents traits pouvant influencer des processus différents de l'écosystème (e.g. processus du N et du C). Dans d'autres systèmes, ces axes peuvent différer de ceux présentés ici, mais les méthodes d'analyse peuvent être universelles.
ISSN: 1286-4560

Droits : info:eu-repo/semantics/OpenAccess
hal-00883621
https://hal.archives-ouvertes.fr/hal-00883621
https://hal.archives-ouvertes.fr/hal-00883621/document
https://hal.archives-ouvertes.fr/hal-00883621/file/hal-00883621.pdf
DOI : 10.1051/forest/2009110

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
The distribution of the lagoon cockle Cerastoderma glaucum is strongly fragmented and usually restricted to isolated, shallow and nontidal lagoons. A high level of genetic structuring was found among the European populations of this species based on mtDNA (COI) sequences, as well as allozymic and microsatellite markers. However, the strengths and geographic locations of the major divisions differed among markers. In the present study we characterized the diversity of a new, potentially universal exon-primed intron-crossing marker, i34, for 17 C. glaucum populations. Allele frequency data at the i34 locus were informative and relevant with respect to geography. Multivariate analyses of new data together with previously published microsatellites confirmed the divergent character of the Ionian Sea and the Aegean-Ponto-Caspian populations, but also revealed the existence of a genetic cline from the Bay of Biscay to the Baltic Sea. Some noncongruent patterns among loci were detected, which may reflect either differential introgression along the genome at the hypothetical contact zone, or selective sweeps. This strong genetic differentiation, and the occurrence of private alleles, may hint at the presence of cryptic species within C. glaucum.
ISSN: 0260-1230

hal-01444646
https://hal.archives-ouvertes.fr/hal-01444646
DOI : 10.1093/mollus/eyw019

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The present study aims at better deciphering the different mechanisms involved in the functioning of the subduction interplate. A 2D thermo-mechanical model is used to simulate a subduction channel, made of oceanic crust, free to evolve. Convergence at constant rate is imposed under a 100 km thick upper plate. Pseudo-brittle and non-Newtonian behaviours are modelled. The influence of the subduction channel strength, parameterized by the difference in activation energy between crust and mantle () is investigated to examine in detail the variations in depth of the subduction plane down-dip extent, . First, simulations show that numerical resolution may be responsible for an artificial and significant shallowing of if the weak crustal layer is not correctly resolved. Second, if the age of the subducting plate is 100 Myr, subduction occurs for any . The stiffer the crust is, that is, the lower is, the shallower is (60 km depth if kJ/mol) and the hotter the fore-arc base is. Conversely, imposing a very weak subduction channel ( J/mol) leads there to an extreme mantle wedge cooling and inhibits mantle melting in wet conditions. Partial kinematic coupling at the fore-arc base occurs if kJ/mol. If the incoming plate is 20 Myr old, subduction can occur under the conditions that the crust is either stiff and denser than the mantle, or weak and buoyant. In the latter condition, cold crust plumes rise from the subduction channel and ascend through the upper lithosphere, triggering (1) partial kinematic coupling under the fore-arc, (2) fore-arc lithosphere cooling, and (3) partial or complete hindrance of wet mantle melting. then ranges from 50 to more than 250 km depth and is time-dependent if crust plumes form. Finally, subduction plane dynamics is intimately linked to the regime of subduction-induced corner flow. Two different intervals of are underlined: 80–120 kJ/mol to reproduce the range of slab surface temperature inferred from geothermometry, and 10–40 kJ/mol to reproduce the shallow hot mantle wedge core inferred from conditions of last equilibration of near-primary arc magmas and seismic tomographies. Therefore, an extra process controlling mantle wedge dynamics is needed to satisfy simultaneously the aforementioned observations. A mantle viscosity reduction, by a factor 4–20, caused by metasomatism in the mantle wedge is proposed. From these results, I conclude that the subduction channel down-dip extent, , should depend on the subduction setting, to be consistent with the observed variability of sub-arc depths of the subducting plate surface.
ISSN: 0031-9201

hal-01623155
https://hal.archives-ouvertes.fr/hal-01623155
DOI : 10.1016/j.pepi.2017.05.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We report paleomagnetic results from four overlapping stratigraphic sections (55 flows) through the lava pile in Tjörnes peninsula (North Iceland). The initial aim of our study was to check the existence of intermediate directions previously interpreted as belonging to the Matuyama-Brunhes geomagnetic reversal (MBR), and complete this record with Thellier-Thellier paleointensity determinations and 40Ar/39Ar radioisotopic dating. The directional results corroborate the findings by Kristjánsson et al. (1988): a sequence of reversed, transitional, normal, and transitional polarity (R-T-N-T) is found in each section. The polarity change is characterized by a jump from reversed virtual geomagnetic poles (VGPs) to a quasi-cluster of transitional VGPs located over China, followed by a second jump to a cluster of normal polarity before moving again towards intermediate polarities. Reversely magnetized flows exhibit a magnetic mineralogy well suited for paleointensity determination. Of these 25 flows, 20 yielded paleointensity estimates of good quality. Unfortunately, the systematic presence of coarse multidomain (MD) titanomagnetite in the transitional and normal polarity flows hampered paleointensity estimates for these flows. The Virtual Dipole Moments (VDM) calculated for the reversed polarity flows vary from 4.9 to 7.0 × 1022 Am2 with an arithmetic mean value of 5.5 ± 0.8 × 1022 Am2. This value is identical to the mean VDM obtained for the 0.3-5 Ma time window and thus strengthens the conclusion that the recent geomagnetic field strength is anomalously high compared to that older than 0.3 Ma. 40Ar/39Ar isochron ages were obtained with the incremental heating technique on groundmass separates or phenocryst-poor whole rock samples. Six of the transitionally magnetized lavas yielded isochron ages that are indistinguishable from one another at the 95% confidence level. The weighted average age is 862 ± 51 ka. In the upper part of this volcanic sequence, the normally magnetized flows yielded a weighted average age of 787 ± 40 ka. This finding supports the conclusion that a geomagnetic excursion within the Matuyama chron is recorded in the lower part of the Tjörnes volcanic sequence, whereas only the latest portion of the MBR is recorded by flows in the upper part of the lava pile. This conclusion is supported via comparison of the VGPs obtained from the lavas with those predicted by a geomagnetic field model.
ISSN: 0012-821X

hal-00618515
https://hal.archives-ouvertes.fr/hal-00618515
https://hal.archives-ouvertes.fr/hal-00618515/document
https://hal.archives-ouvertes.fr/hal-00618515/file/Camps-epsl2011.pdf
DOI : 10.1016/j.epsl.2011.07.026

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Chaperone synthesis in response to proteotoxic stress is dependent on a family of transcription factors named heat shock factors (HSFs). The two main factors in this family, HSF1 and HSF2, are co-expressed in numerous tissues where they can interact and form heterotrimers in response to proteasome inhibition. HSF1 and HSF2 exhibit two alternative splicing isoforms, called α and β, which contribute to additional complexity in HSF transcriptional regulation, but remain poorly examined in the literature. In this work, we studied the transcriptional activity of HSF1 and HSF2 splicing isoforms transfected into immortalized Mouse Embryonic Fibroblasts (iMEFs) deleted for both Hsf1 and Hsf2, under normal conditions and after proteasome inhibition. We found that HSF1α is significantly more active than the β isoform after exposure to the proteasome inhibitor MG132. Furthermore, we clearly established that, while HSF2 had no transcriptional activity by itself, short β isoform of HSF2 exerts a negative role on HSF1β-dependent transactivation. To further assess the impact of HSF2β inhibition on HSF1 activity, we developed a mathematical modelling approach which revealed that the balance between each HSF isoform in the cell regulated the strength of the transcriptional response. Moreover, we found that cellular stress such as proteasome inhibition could regulate the splicing of Hsf2 mRNA. All together, our results suggest that relative amounts of each HSF1 and HSF2 isoforms quantitatively determine the cellular level of the proteotoxic stress response.
ISSN: 1932-6203

inserm-00814784
http://www.hal.inserm.fr/inserm-00814784
http://www.hal.inserm.fr/inserm-00814784/document
http://www.hal.inserm.fr/inserm-00814784/file/journal.pone.0056085.pdf
DOI : 10.1371/journal.pone.0056085

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : Dehydration reactions result in minerals’ replacement and a transient fluid-filled porosity. These reactions involve interface-coupled dissolution–precipitation and might therefore lead to fixed crystallographic orientation relations between reactant (protolith) and product phases (i.e. topotaxy). We investigate these two phenomena in the dehydration of a foliated antigorite (atg) serpentinite by comparing the crystallographic preferred orientation (CPO) developed by olivine (ol), orthopyroxene (opx) and chlorite (chl) during high-pressure antigorite and chlorite dehydration in piston-cylinder experiments and in natural samples recording the dehydration of antigorite (Cerro del Almirez, Betic Cordillera, Spain). Experiments were performed under undrained conditions resulting in fluid-filled porosity and in strong CPO of the prograde minerals, controlled by the pre-existing antigorite CPO in the reactant foliated serpentinite. The orientation of a ol,opx and c∗chl is parallel to c∗atg from the protolith. The Cerro del Almirez samples show similar, locally well-developed topotactic relations between orthopyroxene, chlorite and antigorite, but the product CPOs are weaker and more complex at the thin section scale. In contrast to the experiments, olivine from natural samples shows a weak correlation between b ol and the former c∗atg. We relate the strengthening of local topotactic relations and the weakening of the inherited CPO at a larger scale in natural samples to compaction and associated fluid migration. Microstructural features that might be related to compaction in the natural samples include: (1) smooth bending of the former foliation, (2) gradual crystallographic misorientation (up to 16°) of prismatic orthopyroxene due to buckling by dislocation creep, (3) inversion of enstatite to low clinoenstatite (P21/c) along lamellae and (4) brittle fracturing of prismatic orthopyroxene enclosed by plastically deformed chlorite. The coexistence of orthopyroxene buckling and clinoenstatite lamellae enables estimating the local strain rates and shear stresses generated during compaction. An lower bound for the strain rates in the order of 10−12 to 10−13 s−1 and shear stresses of 60–70 MPa are estimated based on creep data. Lower shear stresses (20–40 MPa) are retrieved using a theoretical approach. These data point to slow compaction (and fluid extraction) in nature if the system is not perturbed by external forces, with rates only marginally higher than the viscoplastic deformation of the solid matrix.
ISSN: 0010-7999

hal-01174158
https://hal.archives-ouvertes.fr/hal-01174158
DOI : 10.1007/s00410-015-1129-4

Éditeur(s) : HAL CCSD Geological Society of London
Résumé : International audience
The mylonitic Cambrian quartzites, Moine Thrust Zone, NW Scotland, have long been used to study microstructural and petrofabric evolution and to develop understanding of grain-scale processes accommodating large-scale displacements. Today, structural geology is entering a new age of understanding of the basic processes involved in microstructural evolution due to the emergence of novel instrumental techniques and theoretical models. It seems apposite therefore to re-evaluate the microstructure of one example of this classic quartz mylonite from the Stack of Glencoul, Assynt, using arguably the most important of these new techniques, electron backscattered diffraction (EBSD). The three-dimensional (3D) microstructure and petrofabric of this rock was analysed using EBSD, to: 1) corroborate previous optical and X-ray texture goniometry measurements; 2) investigate the potential for sampling and/or tectonic sectioning bias that may be introduced inadvertently into any petrofabric analysis; and 3) predict its seismic properties. It is found that microstructures do differ between orthogonal structural sections, leading to variations in strengths of different components in the overall petrofabric that might impact on seismic properties. The results emphasize the true 3D nature of microstructures and petrofabrics, which can be recognized and accommodated more readily by this new generation of analytical techniques.
Continental Tectonics and Mountain Building: The Legacy of Peach and Horne

hal-00565749
https://hal.archives-ouvertes.fr/hal-00565749

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The analysis of three cataclastic band sets from Provence (France) reveals that the band density, their conjugate angles, their ratio of shear displacement to compaction, and the amount of cataclasis within the bands differ and can be expressed as functions of tectonic setting and petrophysical properties. We identify (1) a dense and closely spaced network of shear-enhanced (reverse) compaction bands; (2) a regularly spaced less dense network of reverse compactional shear bands; and (3) a localized network of normal shear bands. The field data show that strain localization is favored in an extensional regime and is characterized by shear bands with a large shear to compaction ratio and a small conjugate band angle. In contrast, distributed strain is favored in a contractional regime and is characterized by compactional bands with a low ratio of shear to compaction and a large conjugate band angle. To explain the mechanical origin of this strain localization, we quantify the yield strength and the stress evolution in extensional and contractional regimes in a frictional porous granular material. We propose a model of strain localization in porous sands as a function of tectonic stresses, burial depth, material properties, strain hardening and fluid pressure. Our model suggests that stress reduction, inherent to extensional regime, favors strain localization as shear bands, whereas stress increase during contraction favors development of compactional bands.
ISSN: 0191-8141

hal-00856921
https://hal.archives-ouvertes.fr/hal-00856921
DOI : 10.1016/j.jsg.2012.11.011

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
Microbial-based indicators, such as C and N contents or microbial functions involved in C and N cycles, are currently used to describe the status of soils in disturbed areas. Microbial functions are more accurate indicators but their measurement for studies at the ecosystem level remains problematical because of the huge spatial variability of these processes and, consequently, of the large number of soil samples which must be analyzed. Our goal was to test the capacity of near-infrared reflectance spectroscopy (NIRS) to predict respiration and denitrification but also carbon and nitrogen contents of soils submitted to various procedures of restoration. To achieve this objective, we took advantage of an experiment conducted on a reforestation system established after open-cast gold mining in French Guiana. In this experimental station, plantations of various ages and various soil textures were at our disposal. Our results showed that both plantations and soil texture had a strong impact on the recovery of soil functioning: carbon and nitrogen contents, respiration and denitrification increased with age of plantation and clay content. Calibrations were performed between spectral data and microbial-based indicators using partial least squares regression (PLS). The results showed that C and N contents were accurately predicted. Microbial functions were less precisely predicted with results more accurate on clayey soils than on sandy soils. In clayey soils, perturbed or restored soils and the year of plantation were discriminated very efficiently through principal component analyses of spectral signatures (over 80% of variance explained on the first two axes). Near-infrared spectroscopy may thus be extended to the prediction of functional soil parameters, but the capacity of this method must be strengthened by expending the databases with other soils in other contexts. The possibility of using NIRS provides many opportunities for understanding both the temporal dynamics and the spatial variability of the recovery of key microbial functions during soil restoration.
ISSN: 0929-1393

hal-01032188
https://hal.archives-ouvertes.fr/hal-01032188
DOI : 10.1016/j.apsoil.2007.07.001

Éditeur(s) : HAL CCSD Springer-Verlag Berlin Heidelberg
Résumé : International audience
Reaction wood produces very peculiar maturation stresses at the tree periphery i.e. compressive stress or very high tensile stress, for compression and tension wood respectively, as compared to moderately high tensile stress for normal wood. This means that both its mechanical state and its mechanical and physical properties differ from normal wood. Compression wood shows big differences from normal wood in conifers, for all physical and mechanical properties: higher density and axial crushing strength (MOR) but lower modulus of elasticity (MOE), far higher axial (longitudinal) shrinkage but lower radial and tangential shrinkage, sometimes even lower than the axial shrinkage. For tension wood things are less simple and can vary a lot from hardwood species to species. Globally there are no systematic differences in density and transverse shrinkage, MOE tends to be a little higher while MOR is slightly lower. However, axial shrinkage is much higher for tension wood with a gelatinous layer (G layer) than normal wood due to the specific gel like organization of cellulose microfibrils in the G layer. For tension wood without a G layer(which is rather frequent) axial shrinkage in the first drying operation is around two times higher than in normal wood mainly because of a kind of hygro-thermal release of locked in maturation stress. Overall the very high tensile stress and stored elastic energy in tension wood lead to problemsin wood processing (end splitting and board warping), which is far less the case for compression wood. But due to the large difference in properties relative to normal wood, compression wood occurrence is always a big problem for the in service behaviour of timber, which is seldom the case for tension wood.
The biology of reaction wood

ISBN : 978-3-642-10813-6
hal-01135273
https://hal.archives-ouvertes.fr/hal-01135273

Éditeur(s) : Gauthier-Villars
Résumé : The wind, temperature and current data collected during the joined French-USA FOCAL/SEQUAL programme carried in the equatorial Atlantic band in 1983 and 1984, allowed for the first time a simultaneous study of both the equatorial and coastal (5-degrees-N) upwellings along 4-degrees-W. At the equator, the decreases of both the surface temperature and the depth of the thermocline in boreal summer are correlated with the zonal component of the local windstress in the period band 1-2 months. This corresponds to the time required by the thermocline to lift up at 0-4-degrees-W in the presence of an easterly wind. The local wind cannot however explain the entire vertical variability of the thermal structure at 0-4-degrees-W. The correlation function shows in addition that the temperature there is highly correlated to the wind recorded at St Peter and St Paul Rocks (SPP) in the period band 0-2 months. This time scale is the one required by the Kelvin and Rossby waves to propagate along the equator through equatorial wave guide dynamics. The influence of these waves seems particularly important when considering the upward displacements of the thermocline both in February-March when the winds abruptly relax and in November-December when the wind at 0-4-degrees-W is southwesterly with no secondary negative maximum in the wind record at 1-degrees-N-29-degrees-W (SPP), contrary to the climatological wind field. The computation of the different terms of the heat equation applied to an homogeneous surface layer shows that the cooling is entirely due to vertical advection and eddy diffusion. The cooling would be more effective without the atmospheric heat flux and the horizontal advection of heat transported both by the South Equatorial Current at the surface and the southward current at the bottom of the mixed layer. At the coast, the amplitude and duration of the upwellings are not constant all along the coast: in boreal summer, they are maximum east of the two capes (Palmas and Three Pointes) while in winter the strength of the cooling is maximum in the east of Cape Palmas and then decreases eastward. The meridional slope of the thermocline off the coast concerns a distance which is much larger than the internal Rossby radius of deformation and is coherent with the latitudinal extension and intensity of the Guinea current both in summer and winter. In addition to this geostrophic adjustment, the upward tilt of the thermocline in summer is enhanced by the intensification of the component of the wind parallel to the coast. The application of a simple linear model forced with an eastward wind at that time explains the surface maximum cooling at the coast and the current distribution in both vertical and meridional directions. The two maxima of the zonal component of the Guinea current, in summer (main one) and in winter are in phase with the intensity of the vertical component of the windcurl. The application of the Sverdrup equations shows that the current speeds computed, for both seasons, are of the same order of magnitude as the speeds observed.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1991 , Vol. 14 , N. 3 , P. 223-240

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00101/21252/18865.pdf
http://archimer.ifremer.fr/doc/00101/21252/

Résumé : Les risques naturels majeurs constituent une menace plus ou moins récurrente pour la plupart des populations de la planète. Les catastrophes naturelles sont à la fois sources et révélatrices d’inégalités sociales et environnementales, dans le monde, mais aussi sur le territoire de la République française. Les Antilles françaises sont très fréquemment, et très lourdement frappées par les aléas naturels. La réponse en matière de gestion des crises, et, en amont, en matière de prévention, ne nous semble pas à la hauteur des défis, et des besoins des populations. C’est la raison pour laquelle nous nous interrogeons, à travers la présente thèse, sur la place de la solidarité et de l’égalité, dans le régime juridique des risques naturels majeurs. C’est une préoccupation doctrinale majeure, inscrite dans la constitution. La recherche du lien entre droit des risques naturels majeurs et justice sociale et environnementale est l’objet de la présente étude, s’agissant de la réponse juridique à la préoccupation des populations et catégories défavorisées, qui s’avèrent a priori les plus atteintes par les catastrophes naturelles. Les limites des textes, l’insuffisance des moyens, ainsi que les pratiques locales, facteurs d’aggravation des vulnérabilités, le laxisme des pouvoirs publics nationaux et territoriaux, l’absence de culture de risque et l’esprit « kokagneur » des populations (avec des différences de comportement entre la Guadeloupe et la Martinique), toutes ces considérations rendent illusoire la détermination proclamée des pouvoirs publics de résoudre les problèmes de risques naturels majeurs. Des voies d’un renforcement de la solidarité sont proposées. Cette contribution à la recherche sur les risques ambitionne d’apporter aux acteurs, une vision transversale de la problématique des risques naturels, par l’analyse du régime juridique confronté à une exigence de justice sociale et environnementale. Les Antilles françaises servent de support à cette étude.
Major natural hazards are more or less recurring threat for most people in the world. Natural disasters are both sources and revealing social and environmental inequalities in the world, but also in the French Republic. The French West Indies are very frequently and strongly hit by natural hazards. The answer in terms of crisis management, and beforehand, in terms of prevention, doesn’t seem to be up to the population’s challenges and needs. This is why we wonder, in this thesis, about the place of solidarity and equality in the legal system of major natural hazards. This is a major doctrinal concern in the constitution. The research of the relationship between major natural hazards law and environmental and social justice is the subject of this study, concerning the legal answer to the concerns of the underprivileged people and categories, which prove to be a priori the most struck by natural disasters. The limits of the legislation, inadequate resources and local practices, vulnerabilities worsening factor, the laxity of the national and territorial public authorities, the lack of risk culture and the "kokagneur" spirit of the populations (with behavior differences between Guadeloupe and Martinique), all these considerations make unreal the government’s proclaimed determination to solve the major natural hazards issues. Ways to strengthen solidarity are proposed. This contribution to risks research aims to bring to the players an interdisciplinary view of natural hazards issues, through the analysis of the legal system confronted with the requirement of social and environmental justice. The French West Indies are used as research support.

http://www.theses.fr/2015AGUY0824/document

Éditeur(s) : HAL CCSD BioMed Central
Résumé : [b]Background[/b]: [i]Amblyomma variegatum[/i] and [i]A. hebraeum[/i] are two ticks of veterinary and human health importance in south-east Africa. In Zimbabwe they occupy parapatric (marginally overlapping and juxtaposed) distributions. Understanding the mechanisms behind this parapatry is essential for predicting the spatio-temporal dynamics of Amblyomma spp. and the impacts of associated diseases. It has been hypothesized that exclusive competition between these species results from competition at the levels of male signal reception (attraction-aggregation-attachment pheromones) or sexual competition for mates. This hypothesis predicts that the parapatry described in Zimbabwe could also be present in other countries in the region. [br/][b]Methods[/b]: To explore this competitive exclusion hypothesis we conducted field surveys at the two species' range limits in Mozambique to identify areas of sympatry (overlapping areas) and to study potential interactions (communicative and reproductive interference effects) in those areas. At sympatric sites, hetero-specific mating pairs were collected and inter-specific attractiveness/repellent effects acting at long and short distances were assessed by analyzing species co-occurrences on co-infested herds and co-infested hosts.[br/] [b]Results[/b]: Co-occurrences of both species at sampling sites were infrequent and localized in areas where both tick and host densities were low. At sympatric sites, high percentages of individuals of both species shared attachment sites on hosts and inter-specific mating rates were high. Although cross-mating rates were not significantly different for[i] A. variegatum[/i] and [i]A. hebraeum[/i] females, attraction towards hetero-specific males was greater for [i]A. hebraeum[/i] females than for A. variegatum females and we observed small asymmetrical repellent effects between males at attachment sites.[br/][b]Conclusions[/b]: Our observations suggest near-symmetrical reproductive interference between [i]A. variegatum[/i] and [i]A. hebraeum[/i], despite between-species differences in the strength of reproductive isolation barriers acting at the aggregation, fixation and partner contact levels. Theoretical models predict that sexual competition coupled with hybrid inviability, greatly reduces the probability of one species becoming established in an otherwise suitable location when the other species is already established. This mechanism can explain why the parapatric boundary in Mozambique has formed within an area of low tick densities and relatively infrequent host-mediated dispersal events.
ISSN: 1756-3305

hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744/document
https://hal.archives-ouvertes.fr/hal-01220744/file/2015%20Bournez%20Parasites%20%26%20Vectors_%7B365AAFF5-7041-480B-9B77-9CD0485A9B72%7D.pdf
DOI : 10.1186/s13071-015-1116-7

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Heat stress is one of the major limiting factors of production efficiency in the swine industry. The aims of the present study were 1) to observe if hemorheological and hematological parameters could be associated to physiological acclimation during the first days of heat stress exposure and 2) to determine if water restriction could modulate the effect of thermal heat stress on physiological, hematological and hemorheological parameters. Twelve Large White male pigs were divided into an ad libitum and a water restricted group. All pigs were submitted to one week at 24 °C (D-7 to D-1). Then, at D0, temperature was progressively increased until 32 °C and maintained during one week (D1 to D7). We performed daily measurements of water and feed intake. Physiological (i.e., skin temperature, rectal temperature, respiratory rate), hematological and hemorheological parameters were measured on D-6, D-5, D0, D1, D2 and D7. Water restriction had no effect on physiological, hematological and hemorheological parameters. The first days of heat stress caused an increase in the three physiological parameters followed by a reduction of these parameters suggesting a successful acclimation of pigs to heat stress. We showed an increase in hematocrit, red blood cell aggregation and red blood cell aggregation strength during heat stress. Further, we observed an important release of reticulocytes, an increase of red blood cell deformability and a reduction of feed intake and blood viscosity under heat stress. This study suggests that physiological acute adaptation to heat stress is accompanied by large hematological and hemorheological changes.
ISSN: 1932-6203

hal-01210648
https://hal.archives-ouvertes.fr/hal-01210648
DOI : 10.1371/journal.pone.0102537
PRODINRA : 269557
PUBMED : 25013960

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Quartz is a common crustal mineral that deforms plastically in a wide range of temperatures and pressures, leading to the development of different types of crystallographic preferred orientation (CPO) patterns. In this contribution we present the results of an extensive modeling of quartz fabric transitions via a viscoplastic self-consistent (VPSC) approach. For that, we have performed systematic simulations using different sets of relative critical resolved shear stress of the main quartz slip systems. We have performed these simulations in axial compression and simple shear regimes under constant Von Mises equivalent strain of 100% (γ = 1.73), assuming that the aggregates deformed exclusively by dislocation glide. Some of the predicted CPOs patterns are similar to those observed in naturally and experimentally deformed quartz. Nevertheless, some classical CPO patterns usually interpreted as result from dislocation glide (e.g. Y-maxima due to prism < a > slip) are clearly not developed in the simulated conditions. In addition we reported new potential preferred orientation patterns that might happen in high temperature conditions, both in axial compression and simple shear. We have demonstrated that CPOs generated under axial compression are usually stronger that those predicted under simple shear, due to the continuous rotation observed in the later simulations. The fabric strength depends essentially on the dominant active slip system, and normally the stronger CPOs result from dominant basal slip in < a >, followed by rhomb < a > and prism [c] slip, whereas prism < a > slip does not produce strong fabrics. The opening angle of quartz [0001] fabric used as a proxy of temperature seems to be reliable for deformation temperatures of ~ 400 °C, when the main slip systems have similar behaviors.
ISSN: 0040-1951

hal-01115674
https://hal.archives-ouvertes.fr/hal-01115674
DOI : 10.1016/j.tecto.2014.08.011

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Background: During the last decade, French Guiana has been affected by major dengue fever outbreaks. Although this arbovirus has been a focus of many awareness campaigns, very little information is available about beliefs, attitudes and behaviors regarding vector-borne diseases among the population of French Guiana. During the first outbreak of the chikungunya virus, a quantitative survey was conducted among high school students to study experiences, practices and perceptions related to mosquito-borne diseases and to identify socio-demographic, cognitive and environmental factors that could be associated with the engagement in protective behaviors. Methodology/Principal Findings: A cross-sectional survey was administered in May 2014, with a total of 1462 students interviewed. Classrooms were randomly selected using a two-stage selection procedure with cluster samples. A multiple correspondence analysis (MCA) associated with a hierarchical cluster analysis and with an ordinal logistic regression was performed. Chikungunya was less understood and perceived as a more dreadful disease than dengue fever. The analysis identified three groups of individual protection levels against mosquito-borne diseases: “low” (30%), “moderate” (42%) and “high” (28%)”. Protective health behaviors were found to be performed more frequently among students who were female, had a parent with a higher educational status, lived in an individual house, and had a better understanding of the disease. Conclusions/Significance: This study allowed us to estimate the level of protective practices against vector-borne diseases among students after the emergence of a new arbovirus. These results revealed that the adoption of protective behaviors is a multi-factorial process that depends on both sociocultural and cognitive factors. These findings may help public health authorities to strengthen communication and outreach strategies, thereby increasing the adoption of protective health behaviors, particularly in high-risk populations. © 2016 Fritzell et al.
ISSN: 1935-2727

hal-01467556
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01467556
DOI : 10.1371/journal.pntd.0005081
PUBMED : 27802275

Résumé : L’incorporation de sous-produits agricoles ou de matériaux naturels dans la matrice cimentaire confère des propriétés intéressantes aux composites élaborés. L’objectif de cette thèse est d’élaborer un matériau pouvant répondre aux exigences mécaniques, thermiques et de durabilité des matériaux de construction en zone tropicale humide. Dans un premier temps, l’activité pouzzolanique d’une pouzzolane naturelle, de cendres de tronc de bambou et de cendres de bagasse de canne à sucre ont été évaluées. L’influence de leur incorporation a été ensuite étudiée sur les propriétés mécaniques et la durabilité des mortiers exposés à des ions chlorures et sulfates. Dans un second temps, l’influence de l’ajout de fibres de bagasse sur les propriétés thermiques et mécaniques des composites a été étudiée en fonction de différents paramètres (teneur en fibres, environnement de vieillissement, type de matrice cimentaire).Les résultats obtenus ont permis de montrer que les matériaux étudiés possèdent une activité pouzzolanique et qu’il est possible de les incorporer au ciment afin de lutter contre la corrosion. De plus, les composites élaborés avec des fibres de bagasse sont plus isolants que ceux élaborés sans fibres. Cependant, du point de vue des propriétés mécaniques, l’incorporation de fibres de bagasse diminue les contraintes à la flexion des composites.
The incorporation of crop wastes or natural materials in the cement matrix confers interesting properties to composites prepared. The aim of this thesis is to develop a material that can reach the mechanical, thermal and durability requirements for building materials in the humid tropical zone. Firstly, pozzolanic activity of a natural pozzolan, bamboo stem and sugar cane bagasse ashes has been determined. Influence of their incorporation on mechanical properties and durability of mortars exposed to chloride and sulphate ions was studied. Secondly, influence of addition of bagasse fibers on thermal and mechanical properties of composites was studied as a function of various parameters (fibers content, curing, type of cement matrix).These results has shown that the materials studied have pozzolanic activity and it is possible to incorporate them into the cement to fight against corrosion. Moreover, composites elaborated with bagasse fibers are more insulating than those elaborated without fibers. However, from the viewpoint of mechanical properties, incorporation of bagasse fibers decreases flexural strength of composites in the present work and under the conditions producing procedures that were adopted.

http://www.theses.fr/2014AGUY0804/document

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
BACKGROUND AND AIMS: Determining the sources of variation in floral morphology is crucial to understanding the mechanisms underlying Angiosperm evolution. The selection of floral and reproductive traits is influenced by the plant's abiotic environment, florivores and pollinators. However, evidence that variations in floral traits result from mutualistic interactions with insects other than pollinators is lacking in the published literature and has rarely been investigated. We aimed to determine whether the association with either Camponotus femoratus or Pachycondyla goeldii (both involved in seed dispersal and plant protection) mediates the reproductive traits and allocation of Aechmea mertensii, an obligatory ant-garden tank-bromeliad, differently. METHODS: Floral and reproductive traits were compared between the two A. mertensii ant-gardens. The nitrogen flux from the ants to the bromeliads was investigated through experimental enrichments with stable isotopes ((15)N). KEY RESULTS: Camponotus femoratus-associated bromeliads produced inflorescences up to four times longer than did P. goeldii-associated bromeliads. Also, the numbers of flowers and fruits were close to four times higher, and the number of seeds and their mass per fruit were close to 1*5 times higher in C. femoratus than in P. goeldii-associated bromeliads. Furthermore, the (15)N-enrichment experiment showed that C. femoratus-associated bromeliads received more nitrogen from ants than did P. goeldii-associated bromeliads, with subsequent positive repercussions on floral development. Greater benefits were conferred to A. mertensii by the association with C. femoratus compared with P. goeldii ants. CONCLUSIONS: We show for the first time that mutualistic associations with ants can result in an enhanced reproductive allocation for the bromeliad A. mertensii. Nevertheless, the strength and direction of the selection of floral and fruit traits change based on the ant species and were not related to light exposure. The different activities and ecological preferences of the ants may play a contrasting role in shaping plant evolution and speciation.
ISSN: 0305-7364

hal-00819112
https://hal.archives-ouvertes.fr/hal-00819112
DOI : 10.1093/aob/mcr253
PUBMED : 21984729