Éditeur(s) : HAL CCSD Springer
Résumé : International audience
This contribution is an attempt to present a self-contained and comprehensive survey of the mathematics and physics of material behavior of rocks in terms of texture and anisotropy. Being generally multi-phase and poly-crystalline, where each single crystallite is anisotropic with respect to its physical properties, texture, i.e., the statistical and spatial distribution of crystallographic orientations becomes a constitutive characteristic and determines the material behavior except for grain boundary effects, i.e., in first order approximation. This chapter is in particular an account of modern mathematical texture analysis, explicitly clarifying terms, providing definitions and justifying their application, and emphasizing its major insights. Thus, mathematical texture analysis is brought back to the realm of spherical Radon and Fourier transforms, spherical approximation, spherical probability, i.e., to themathematics of spherical tomography
Handbook of Geomathematics

hal-00564939
https://hal.archives-ouvertes.fr/hal-00564939

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
Wadsleyites with various iron contents were synthesized at ~12-14 GPa and 1400 °C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and Mössbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ~30% Fe3+/Fetotal. Two XANES results were cross-checked by Mössbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm−1 and a new band located at 3500 cm−1. The intensity of these two bands is higher for Fe3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., XFe/(XFe + XMg) × 100 ratio]. The divalent cation concentrations (i.e., Mg2+ + Fe2+), the Si as well as the H content in wadsleyite decrease with increasing Fe3+ content, indicating an incorporation mechanism via substitution into the metal (Me = Mg2+ and Fe2+) and Si sites with a ratio of 5/3 for (Fe3++H+):Me and of 5/1 for (Fe3++H+):Si, similarly as in the dry system. Thus, coupled substitution of Fe3+ and H+ does not affect the incorporation mechanism of Fe3+, but does affect the location of H+, which is partly incorporated at tetrahedral edges forming [FeSi′-(OH)o*]X neutral defects substituting for Si. In this model 25% of the ferric iron occupies the tetrahedral sites.
ISSN: 0003-004X

hal-00758071
https://hal.archives-ouvertes.fr/hal-00758071
DOI : 10.2138/am.2012.3869

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
To test if hydrogen incorporation by ionic diffusion can occur between a volatile-rich kimberlitic liquid and forsterite, results of high-pressure and high-temperature experiments using a piston-cylinder apparatus at 1200–1300 °C and 1 GPa for durations of 1 min, 5 h, and 23 h, are reported here. Kimberlitic liquid in the system CaO-MgO-Al2O3-SiO2-CO2-H2O and synthetic forsterite single crystals were chosen as a first simplification of the complex natural kimberlite composition. Unpolarized Fourier transform infrared spectroscopy was used to quantify the concentrations of OH in the crystallographically oriented forsterite. Scanning electron microscopy, electron backscattered diffraction, electron microprobe analyses, and transmission electron microscopy were performed to identify the run products. After 5 and 23 h, a forsterite overgrowth crystallized with the same orientation as the initial forsterite single crystal. The kimberlitic liquid has crystallized as micrometer-scale euhedral forsterite neocrystals with random crystallographic orientations, as well as a nanoscale aluminous phase and a calcic phase. Despite theoretical water-saturation of the system and long duration, none of the initial forsterite single crystals display signs of hydration such as hydrogen diffusion profile from the border toward the center of the crystal. Most likely, the presence of CO2 in the system has lowered the H2O fugacity to such an extent that there is no significant hydration of the starting forsterite single crystal or its overgrowth. Also, the presence of CO2 enhances rapid forsterite crystal growth. Forsterite growth rate is around 2 × 108 μm3/h at 1250 °C. These experimental results suggest a deep mantle origin of the high OH content found in natural mantle-derived xenoliths transported in kimberlites, as reported from the Kaapvaal craton. In agreement with previous studies, it also points out to the fact that significant hydration must take place in a CO2-poor environment.
ISSN: 0003-004X

hal-01217157
https://hal.archives-ouvertes.fr/hal-01217157
DOI : 10.2138/am-2015-5200

Éditeur(s) : HAL CCSD Springer Verlag
Résumé :  
In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers' predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.
ISSN: 0028-1042

hal-01032079
https://hal.archives-ouvertes.fr/hal-01032079
DOI : 10.1007/s00114-008-0448-y

Éditeur(s) : HAL CCSD
Résumé : International audience
(Guava (Psidium guajava L.) is a tropical fruit widely consumed around the world. The study wascarried out on four selected guava varieties grown in Martinique. Two fruit harvests were gathered at two-yearintervals, at the green/yellow color change maturity stage. First, we established the homogeneity of all fruitbatches by bootstrapping, ANOVA, box plot and multiple comparison statistical analysis on physicalparameters. Red Supreme Ruby clearly differs from the other three varieties, whereas the results for CentenoProlific are between Beauséjour and Enana Cuba. We determined on puree obtained from a homogeneousbatch of each variety the physicochemical and functional properties as well as the antioxidant properties. Ourresults show that the combination of lycopene and vitamin C, and their synergistic mechanisms in the fruitextracts may be responsible for the high antioxidant activity of guava puree, and we demonstrate a statisticallysignificant positive correlation between EC50 and lycopene.
IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT)

hal-01672064
https://hal.univ-antilles.fr/hal-01672064
DOI : 10.9790/2402-1109015767

Éditeur(s) : HAL CCSD
Résumé : International audience
Indic scripts are among few scripts in the world that have had continuous development for more than two millennia. The modern forms of the scripts are the result of infinitesimal changes in handwriting being accumulated over centuries. They present us with a unique opportunity to understand various changes occurring in handwriting behavior. We have taken four major Indic scripts in six different stages of evolution and extracted features quantifying their handwriting behavior. We have derived these features by applying the principles of handwriting production and gesture analysis on a paleographic data set. We present various trends and behaviors that occurred during script development and discuss our interpretation of the results in terms of evolution of handwriting behavior. We then briefly discuss the detailed analyses that will be performed on the dataset in the future. We also consider the applications of these results in digital paleography and handwriting-driven systems.
17th Biennial Conference of the International Graphonomics Society
Pointe-à-Pitre, Guadeloupe

hal-01165770
https://hal.univ-antilles.fr/hal-01165770
https://hal.univ-antilles.fr/hal-01165770/document
https://hal.univ-antilles.fr/hal-01165770/file/IGS_2015_submission_8.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
The natural science education aims to help children build a rational representation of their environment. In this perspective it is usual to build authentic teaching by implementing a process of investigation rooted in a particular ecological context. Previous studies have described the effects of context as events occurring in a learning situation when two participant bring contrastive contexts. But these context effects were never filmed in science learning. We postulate that the effects of contexts can be considered not as a limit to learning but as an asset. In addition, we believe it is possible to build science lessons based on their emergences.The objective of this internationnal project called gounouy is to build an educational innovation for recording and description of effect of context and their interest in learning. It involved four research laboratories (two in Guadeloupe CRREF and LARGE, two in Quebec LICEF and GDAC) and two schools. In a design methodology based research, many direct and indirect data have been collected. They are constitute by videos, student productions, digital items (vidéoconférence and digital workspace) and interviews with students. The results show two different types of expression of context effects and different learning indicators. Adaptations and limits reuse of this new type of education will be discussed.Following a design based research methodology, many direct and indirect data on learning situations have been collected. They are constitute by videos, student, digital items videoconference, digital workspace) and interviews with students. The results show two different types of expression of context effects and different learning indicators. Adaptations and limits of this new type of education will be discussed.
Biennial Conference of Caribbean Academy of Sciences
Tobago, Trinidad and Tobago

hal-01539476
https://hal.univ-antilles.fr/hal-01539476

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : The diversity and functional identity of organisms are known to be relevant to the maintenance of ecosystem processes but can be variable in different environments. Particularly, it is uncertain whether ecosystem processes are driven by complementary effects or by dominant groups of species. We investigated how community structure (i.e., the diversity and relative abundance of biological entities) explains the community-level contribution of Neotropical ant communities to different ecosystem processes in different environments. Ants were attracted with food resources representing six ant-mediated ecosystem processes in four environments: ground and vegetation strata in cropland and forest habitats. The exploitation frequencies of the baits were used to calculate the taxonomic and trophic structures of ant communities and their contribution to ecosystem processes considered individually or in combination (i.e., multifunctionality). We then investigated whether community structure variables could predict ecosystem processes and whether such relationships were affected by the environment. We found that forests presented a greater biodiversity and trophic complementarity and lower dominance than croplands, but this did not affect ecosystem processes. In contrast, trophic complementarity was greater on the ground than on vegetation and was followed by greater resource exploitation levels. Although ant participation in ecosystem processes can be predicted by means of trophic-based indices, we found that variations in community structure and performance in ecosystem processes were best explained by environment. We conclude that determining the extent to which the dominance and complementarity of communities affect ecosystem processes in different environments requires a better understanding of resource availability to different species.
ISSN: 0029-8549

hal-01606497
https://hal.archives-ouvertes.fr/hal-01606497
DOI : 10.1007/s00442-016-3741-z
PRODINRA : 407457

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In order to qualify the fluctuating nature of solar radiation under tropical climate, we classify daily distributions of the clearness index kt by estimating a finite mixture of Dirichlet distributions without assuming any parametric hypothesis on these daily distributions. The method is applied to solar radiation measurements performed in Guadeloupe (16°2 N, 61 W) where important fluctuations can be observed even within a short period of a few minutes. The results put in evidence four distinct classes of distributions corresponding to different types of days. The sequence of such classes can be of interest for prediction.
ISSN: 0038-092X

hal-01527878
https://hal.archives-ouvertes.fr/hal-01527878
DOI : 10.1016/j.solener.2009.01.010

Éditeur(s) : HAL CCSD Elsevier - International Brain Research Organization
Résumé : International audience
Women are more likely to develop depression during childbearing years with up to 20% of women suffering from depression during pregnancy and in the postpartum period. Increased prevalence of depression during the perinatal period has resulted in frequent selective serotonin reuptake inhibitor (SSRI) antidepressant treatment; however the effects of such medications on the maternal brain remain limited. Therefore, the aim of the present study is to investigate the effects of the SSRI medication, fluoxetine, on neurobiological differences in the maternal brain. To model aspects of maternal depression, gestational stress was used. Sprague-Dawley rat dams were exposed to either gestational stress and/or fluoxetine (5mg/kg/day) to form the following four groups: 1. Control+Vehicle, 2. Stress+Vehicle, 3. Control+Fluoxetine 4. Stress+Fluoxetine. At weaning maternal brains were collected. Main findings show that gestational stress alone increased synaptophysin and serotonin metabolism in the CG2 region of the cortex while fluoxetine treatment after stress normalized these effects. In the hippocampus, fluoxetine treatment, regardless of gestational stress exposure, decreased both global measures of methylation in the dentate gyrus, as measured by Dnmt3a immunoreactivity, as well as serotonin metabolism. No further changes in synaptophysin, PSD-95, or Dnmt3a immunoreactivity were seen in the cortical or hippocampal areas investigated. These findings show that gestational stress and SSRI medication affect the neurobiology of the maternal brain in a region-specific manner. This work adds to a much needed area of research aimed at understanding neurobiological changes associated with maternal depression and the role of SSRI treatment in altering these changes in the female brain
ISSN: 0306-4522

hal-01301509
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01301509
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01301509/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01301509/file/Gestational%20stress%20and%20fluoxetine%20treatment%20%281%29.pdf
PUBMED : 27060483

Éditeur(s) : Elsevier
Résumé : The ZoNeCo programme is devoted to the evaluation of the marine resources of the Economic Zone of New Caledonia. The results are essentially dependent on the quality of the seafloor mapping. From 1993 to 1996, four geological and geophysical surveys using the EM12 DUAL multibeam echosounder provided swath-mapping and acoustic imagery data of the seafloor of selected sites on the northern and southern parts of the Norfolk ridge, the Loyalty basin, around the Loyalty islands and in the westernmost part of the Economic Zone of New Caledonia. The accuracy of these documents shows the morphology of the seafloor in detail and allows rocky substratum to be differentiated from muddy bottom. It allows favorable emplacements of future exploratory fishing surveys to be determined. The benefits of swath mapping are illustrated by the Halipro 2 deep sea trawling cruise (1996) which used the swath mapping data of ZoNeCo 1 cruise (1993) on the southern prolongation of the New Caledonia mainland and Loyalty Islands.
Le programme ZoNéCo a pour objectif l'évaluation des ressources marines de la zone économique de Nouvelle-Calédonie. Les résultats du programme dépendent essentiellement de la qualité de la cartographie des fonds marins. De 1993 à 1996, au cours de quatre campagnes bathymétriques et géophysiques, une couverture bathymétrique et d'imagerie a été effectuée en utilisant le sondeur multifaisceaux EM 12 DUAL sur des sites choisis sur les segments Nord et Sud de la ride de Norfolk, dans le bassin des Loyauté, autour des îles Loyauté ainsi qu'à l'ouest de la zone économique de Nouvelle-Calédonie. La qualité des cartes obtenues permet de préciser la morphologie du fond mais aussi de différencier un substratum rocheux d'un substratum couvert par des sédiments et d'identifier les sites favorables à la réalisation de campagne de pêche exploratoire. Les bénéfices de la bathymétrie multifaisceaux sont illustrés, à partir des données de ZoNéCo 1 (1993), par la campagne de chalutage profond Halipro 2 (1996) sur la prolongation méridionale de la Grande Terre de Nouvelle-Calédonie et des îles Loyauté.
Oceanologica Acta (0399-1784) (Elsevier), 1999-11 , Vol. 22 , N. 6 , P. 641-650

Droits : 1999 Ifremer / CNRS / IRD / Editions scientifique et mtdicales Elsevier SAS
http://archimer.ifremer.fr/doc/1999/publication-833.pdf
DOI:10.1016/S0399-1784(00)88955-0
http://archimer.ifremer.fr/doc/00000/833/

Éditeur(s) : Wiley-blackwell
Résumé : Aims Exopolysaccharides (EPS) are industrially valuable molecules with numerous useful properties. This study describes the techniques used for the identification of a novel Vibrio bacterium and preliminary characterization of its EPS. Methods and Results Bioprospection in marine intertidal areas of New Caledonia followed by screening for EPS producing brought to selection of the isolate NC470. Phylogenetic analysis (biochemical tests, gene sequencing and DNADNA relatedness) permitted to identify NC470 as a new member of the Vibrio genus. The EPS was produced in batch fermentation, purified using the ultrafiltration process and analysed by colorimetry, Fourier Transform Infrared spectroscopy, gas chromatography, Nuclear Magnetic Resonance and HPLC-size exclusion chromatography. This EPS exhibits a high N-acetyl-hexosamines and uronic acid content with a low amount of neutral sugar. The molecular mass was 672x103Da. These data are relevant for possible technological exploitation. Conclusions We propose the name Vibrio neocaledonicus sp. nov for this isolate NC470, producing an EPS with an unusual sugar composition. Comparison with other known polymers permitted to select applications for this polymer. Significance and Impact of the Study This study contributes to evaluate the marine biodiversity of New Caledonia. It also highlights the biotechnological potential of New Caledonia marine bacteria.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell), 2013-06 , Vol. 114 , N. 6 , P. 1702-1712

Droits : 2013 The Society for Applied Microbiology
http://archimer.ifremer.fr/doc/00144/25501/24036.pdf
DOI:10.1111/jam.12184
http://archimer.ifremer.fr/doc/00144/25501/

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy B
Résumé : International audience
AIMS: Indications for surgery in acute infective endocarditis (IE) are detailed in guidelines, but their application is not well known. We analysed the agreement between the patient's attending physicians and European Society of Cardiology guidelines regarding indications for surgery. We also assessed whether surgery was performed in patients who had an indication. METHODS AND RESULTS: From the 2008 prospective population-based French survey on IE, 303 patients with definite left-sided native IE were identified. For each case, we prospectively recorded (i) indication for surgery according to the attending physicians and (ii) indication for surgery according to guidelines. Surgery was indicated in 194 (65%) patients according to attending physicians and in 221 (73%) according to guidelines, while 139 (46%) underwent surgery. Agreement was moderate between attending physicians and guidelines (kappa 0.41-0.59) and between indication according to guidelines and the performance of surgery (kappa 0.38). Of the 90 (30%) patients not operated despite indication, contraindication to surgery was reported by the attending physicians in 42 (47%), and indication was not identified in 48 (53%). One-year survival was 76% in patients with indication and surgery performed (n = 131), 69% in patients without indication and no surgery (n = 74), 56% in patients with identified indication and contraindication to surgery (n = 42), and 60% in patients with no identified indication (n = 48; P = 0.059). CONCLUSION: Cardiac surgery during acute IE was recommended in almost three out of four patients, although fewer than half were actually operated. Indication was not acknowledged by the attending physicians in one out of six patients
ISSN: 0195-668X

hal-01255874
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01255874
DOI : 10.1093/eurheartj/ehv650
PUBMED : 26685134

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The symbiotic interaction between cnidarians, such as corals and sea anemones, and the unicellular algae Symbiodinium is regulated by yet poorly understood cellular mechanisms, despite the ecological importance of coral reefs. These mechanisms, including host-symbiont recognition and metabolic exchange, control symbiosis stability under normal conditions, but also lead to symbiosis breakdown (bleaching) during stress. This study describes the repertoire of the sterol-trafficking proteins Niemann-Pick type C (NPC1 and NPC2) in the symbiotic sea anemone Anemonia viridis. We found one NPC1 gene in contrast to the two genes (NPC1 and NPC1L1) present in vertebrate genomes. While only one NPC2 gene is present in many metazoans, this gene has been duplicated in cnidarians, and we detected four NPC2 genes in A. viridis. However, only one gene (AvNPC2-d) was upregulated in symbiotic relative to aposymbiotic sea anemones and displayed higher expression in the gastrodermis (symbiont-containing tissue) than in the epidermis. We performed immunolabelling experiments on tentacle cross sections and demonstrated that the AvNPC2-d protein was closely associated with symbiosomes. In addition, AvNPC1 and AvNPC2-d gene expression was strongly downregulated during stress. These data suggest that AvNPC2-d is involved in both the stability and dysfunction of cnidarian-dinoflagellate symbioses.
ISSN: 0962-1083

hal-01546166
https://hal.archives-ouvertes.fr/hal-01546166
DOI : 10.1111/mec.12876

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Four lyophilizated liver flüke antigens and one of hydatid fluid were examined for the presence of blood group like antigens P1, A, B, M and N by an hemagglutination inhibition test with hyperimmune and natural hemagglutinating sera. P1 or P1-like substance was found in the extracts of "Fasciola hepatica" and "F. gigantica" in a lower concentration than in echinoccocal fluid. This presence may explain the occurrence of anti-P1 antibodies in patients infected with liver flüke and belonging to the P2 blood group. However biochemical studies will be necessary to determine if the P1 activity is due to the blood group P1 substance of the red cell itself or due to a P1 like substance.
ISSN: 0369-8114

hal-00715431
https://hal.univ-antilles.fr/hal-00715431
PUBMED : 392420

Éditeur(s) : ISTPM
Résumé : The 1951 cruise of the "Président-Théodore-Tissier" was conducted from February 13th to June 30th, 1951. During these four and a half months, the vessel, which departed from Brest, stopped successively in Madeira, the French Caribbean, the Bermudas, Woods Hole, Halifax, on the banks of Newfoundland, the Azores Islands, Saint-Jean-de-Luz, and then sailed back to Brest after 13,000 miles in the Northern Atlantic Ocean. The North-Western Atlantic and the Caribbean Pycnogonida have been the focus in 1948 of a very comprehensive and documented review by J. W. Hedgpeth followed by a catalogue of the stations of the different expeditions which worked in the Northern Atlantic Ocean and the studied species. Moreover, the work of Marcus (1940) on the South-American Pycnogonida is an excellent basis for the study of the tropical Atlantic Pycnogonida. Recently, J.-H. Stock (1954 a) published a preliminary study on Pycnogonida collected at small depths in the Caribbean. During the 1951 cruise of the "Président-Théodore-Tissier", 15 species of Pycnogonida were collected at 16 stations which can be classified, from a biogeographic point of view, in five groups of unequal importance: the floating sargassum (8 stations), the Little Caribbean (5 stations), the Bermudas (1 station), the surroundings of Wood Hole (1 station), the banks of Newfoundland (1 station).
La croisière 1951 du « Président-Théodore-Tissier» a duré du 13 février au 30 juin 1951. Pendant ces quatre mois et demi, le navire, parti de Brest, s'est rendu successivement à Madère, aux Antilles française, aux Bermudes, à Woods Hole, à Halifax, sur les Bancs de Terre-Neuve, aux Açores, à Saint-Jean-de-Luz, et est rentré à Brest après avoir parcouru plus de 13.000 milles dan l'Atlantique Nord. Les Pycnogonides de l'Atlantique Nord-Ouest et des Antilles ont fait l'objet en 1948 d'une révision très complète et documentée de J. W. Hedgpeth suivie d'un catalogue des stations des différentes expéditions ayant travaillé dans l'Atlantique Nord et des espèces récoltées. Par ailleurs, le travail de Marcus (1940) sur les Pycnogonides sud-américains constitue une excellente base pour l'étude des Pycnogonides de l'Atlantique tropical. Enfin, tout récemment J.-H. Stock (1954 a) a publié une étude préliminaire des Pycnogonides récoltés à faible profondeur dans les Antilles. Au cour de la campagne 1951 du «Président-Théodore-Tissier », 15 espèces de Pycnogonides ont été recueillies en 16 stations qui peuvent, au point de vue biogéographie, être classés en cinq groupes d'importance très inégale: les sargasses flottantes (8 stations), les petites Antilles (5 stations), les Bermudes (1 station), les environs de Wood Hole (1 station), les Bans de Terre-Neuve (1 station). ATTENTION : Ce texte a été extrait du document par un processus automatique, non contrôlé, de reconnaissance optique de caractères (OCR). Il est donc susceptible de comporter des erreurs. En cas de doute, consultez le fichier PDF.
Revue des Travaux de l'Institut des Pêches Maritimes (0035-2276) (ISTPM), 1955-12 , Vol. 19 , N. 4 , P. 581-609

Droits : Ifremer
http://archimer.ifremer.fr/doc/1955/publication-6612.pdf
http://archimer.ifremer.fr/doc/00000/6612/

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
This work evaluates the influence of three different intensities of refinement of sisal pulp and the effect of accelerated aging cycles on the behavior of composites. Fiber-cements were prepared by the slurry de-watering method and pressing as a crude simulation of the Hatschek process. Mechanical behavior of composites was evaluated by four-point bending test at 28 days, and after 50 and 100 wet/dry cycles. Refinement of pulp and aging have increased the strength and bulk density of composites and decreased the toughness and porosity. The best mechanical performance after aging was achieved for samples with highly refined fibers.
ISSN: 1042-6914

hal-00809817
https://hal.univ-antilles.fr/hal-00809817
DOI : 10.1080/10426910601062065

Éditeur(s) : HAL CCSD Elsevier
Résumé : This study deals with the preliminary data of rare earth elements (REE) obtained on northeastern Algerian phosphorites from the Tébessa region. These phosphorites are located in two different basins: the northern basin represented by Dj. El Kouif, Dj. Dyr and Tazbant showings and the southern basin with the giant Dj. Onk phosphate deposit. The host sedimentary formation is Late Paleocene to Early Eocene. Twenty-six (26) samples from the four (4) localities were collected and analyzed for their REE contents using the ICP-MS technique. Phosphates from the southern basin (Dj. Onk deposit) show ∑REE contents ranging from 174.41 and 906.39 ppm (average ∑REE = 623.01 ppm), while the northern phosphorites have lower ∑REE contents (from 125.45 to 472.44 ppm; average = 265.57 ppm). PAAS-normalized REE patterns and binary Box plot of (Sm/Pr)N vs (Sm/Yb)N show HREE enrichments for samples from the northern localities while most samples from the southern basin are HREE depleted. Normalized (La/Yb)N vs (La/Sm)N plot shows that (La/Sm)N ratios of all samples are similar to those of modern seawater (from 0.83 to 1.55). However, the (La/Yb)N ratios of the two basins are significantly higher (from 0.67 to 1.18), which indicates an early diagenesis. The Ce/Ce* vs Pr/Pr* diagram shows that the observed Ce anomaly was not affected by diagenesis and more likely represents a proxy for redox conditions. The obtained results substantiate that the northern phosphorites were formed in more oxic environment with more pronounced negative Ce anomalies, whereas the southern phosphorites have lower Ce anomalies. Northern phosphorites are different from those from the south probably because the northern basin was more connected to an open sea as did the Sra Ouartan basin in northern Tunisia. These results have also been confirmed by statistical method studies, such as factorial discriminate analysis.
ISSN: 1877-7058

hal-01412572
https://hal.archives-ouvertes.fr/hal-01412572
https://hal.archives-ouvertes.fr/hal-01412572/document
https://hal.archives-ouvertes.fr/hal-01412572/file/kechided2016.pdf
DOI : 10.1016/j.proeng.2016.02.048

Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
We investigated the characteristics of the sulfur-oxidizing symbiont hosted in the gills of Codakia orbicularis, a bivalve living in shallow marine tropical environments. Special attention was paid to describing the heterogeneity of the population by using single-cell approaches including flow cytometry (FCM) and different microscopic techniques and by analyzing a cell size fractionation experiment. Up to seven different subpopulations were distinguished by FCM based on nucleic acid content and light side scattering of the cells. The cell size analysis of symbionts showed that the symbiotic population was very heterogeneous in size, i.e., ranging from 0.5 to 5 _m in length, with variable amounts of intracellular sulfur. The side-scatter signal analyzed by FCM, which is often taken as a proxy of cell size, was greatly influenced by the sulfur content of the symbionts. FCM revealed an important heterogeneity in the relative nucleic acid content among the subclasses. The larger cells contained exceptionally high levels of nucleic acids, suggesting that these cells contained multiple copies of their genome, i.e., ranging from one copy for the smaller cells to more than four copies for the larger cells. The proportion of respiring symbionts (5-cyano-2,3-ditolyl-terazolium chloride positive) in the bacteriocytes of Codakia revealed that around 80% of the symbionts hosted by Codakia maintain respiratory activity throughout the year. These data allowed us to gain insight into the functioning of the symbionts within the host and to propose some hypotheses on how the growth of the symbionts is controlled by the host.
ISSN: 0099-2240

hal-00716079
https://hal.univ-antilles.fr/hal-00716079
DOI : 10.1128/AEM.01683-06

Éditeur(s) : HAL CCSD Cambridge University Press (CUP)
Résumé : International audience
Upper Triassic volcanic and sedimentary rocks of the Mamonia Complex in southwestern Cyprus are exposed in erosional windows through the post-Cretaceous cover, where the Mamonia Complex is tectonically imbricated with the Troodos and Akamas ophiolitic suites. Most of these Upper Triassic volcanic rocks have been considered to represent remnants of Triassic oceanic crust and its associated seamounts. New Nd and Pb isotopic data show that the whole Mamonia volcanic suite exhibits features of oceanic island basalts (OIB). Four rock types have been distinguished on the basis of the petrology and chemistry of the rocks. Volcanism began with the eruption of depleted olivine tholeiites (Type 1) and oceanic island tholeiites (Type 2) associated with deep basin siliceous and/or calcareous sediments. The tholeiites were followed by highly phyric alkali basalts (Type 3) interbedded with pelagic Halobia-bearing limestones or white reefal limestones. Strongly LREE-enriched trachytes (Type 4) were emplaced during the final stage of volcanic activity. Nd and Pb isotopic ratios suggest that tholeiites and mildly alkali basalts derived from partial melting of heterogeneous enriched mantle sources. Fractional crystallization alone cannot account for the derivation of trachytes from alkaline basalts. The trachytes could have been derived from the partial melting at depth of mafic material which shares with the alkali basalts similar trace element and isotopic compositions. This is corroborated by the rather similar isotopic compositions of the alkali basalts and trachytes. The correlations observed between incompatible elements (Nb, Th) and {varepsilon}Nd and Pb isotopic initial ratios suggest that the Mamonia suite was derived from the mixing of a depleted mantle (DMM) and an enriched component of High µ (µ = 238U/204Pb, HIMU) type. Models using both Nd and Pb isotopic initial ratios suggest that the depleted tholeiites (Type 1) derived from a DMM source contaminated by an Enriched Mantle Type 2 component (EM2), and that the oceanic tholeiites (Type 2), alkali basalts (Type 3) and trachytes (Type 4) were derived from the mixing of the enriched mantle source of the depleted tholeiites with a HIMU component. None of the Mamonia volcanic rocks show evidence of crustal contamination. The Upper Triassic within-plate volcanism likely erupted in a small southerly Neotethyan basin, located north of the Eratosthenes seamount and likely floored by oceanic crust.
ISSN: 0016-7568

insu-00353657
https://hal-insu.archives-ouvertes.fr/insu-00353657
DOI : 10.1017/S0016756806002937