Éditeur(s) : Universite Montpellier II
Résumé : Since 1980, the expansion of a green macro-alga: Valonia aegagropila (C Agardh) is observed in Salses-Leucate lagoon (France). It is currently distributed in the north of the lagoon with important biomasses (40 gDW/m²) eroding the cover of Zostera noltii. The free form of the alga can be transported with the surface or bottom currents depending on seasons. It multiplies mainly by vegetative reproduction. There are few studies on the ecophysiological capacities of V. aegagropila. This work tries to answer why (physiological adaptation) and how (mechanical process of transport) the alga invaded the lagoon, with an approach including observations, experiments in controlled environment and biological and hydrodynamic models. The growth capacities depend on temperature and light intensities, the nutrients absorption rates and internal nitrogen and phosphorus internal quotas were measured and modelled using a Droop model based on internal quota. Vertically transport was studied with laboratory experiments and measurements of biomass transport were made into the lagoon. The biological model (growth, vertical transport, mortality) was coupled to the MARS 3D hydrodynamic model with a meshgrid of 160m. The results show an adaptation of the alga to low availability of phosphorus and an annual growth of biomass controlled by the availability of nutrient during winter. The alga seems to occupy the whole zones where growth is optimal and the risk of invasion of the southern part of the lagoon is limited. This work opens on research prospects on an ecological model (confronting physiological capacities and competition of V. aegagropila, Zostera noltii, green algae and primary production), new physiological experiments, ecological observations and potential valorisation of V. aegagropila.
Depuis 1980, est observée dans l'étang de Salses-Leucate l'expansion d'une macro-algue verte : Valonia aegagropila (C. Agardh). En 2004, elle était présente sur la presque totalité de la moitié nord de la lagune avec des biomasses importantes (jusqu'à 600 gPS/m²). L'algue envahit et érode également la couverture d'herbiers garant de la biodiversité, de la productivité et de la stabilité de l'écosystème. V. aegagropila se reproduit essentiellement de manière végétative (fragmentation des thalles) et possède la particularité de retenir de l'oxygène de la photosynthèse dans sa structure sphérique. Cet oxygène piégé lui donne la possibilité de mouvement sur la verticale et d'être transportée dans le domaine par les courants. Les conditions physico-chimiques de l'étang présentent de fortes variations saisonnières en salinité, en température et en turbidité, ainsi que des apports nutritifs faibles : la production primaire est principalement limitée par le phosphore. Il existe malheureusement peu d'informations sur V. aegagropila ainsi que trop peu de connaissances sur son écophysiologie. Elle semble vivre dans des milieux plutôt oligotrophe dans des régions tropicales à sub-tropicales. Ce travail basé sur une approche d'observations de terrain, d'expérimentations en milieu contrôlé (en laboratoire) et de modélisation des processus, a permis d'une part d'explorer les capacités adaptatives physiologiques de V. aegagropila aux conditions environnementales de l'étang et d'autre part de mettre à jour les modes de fonctionnement de la dynamique spatio-temporelle de la population. Les capacités de croissance ont été mesurées sur un large spectre de température et de lumière. Les capacités d'absorption des sels nutritifs dans l'eau et les facultés de l'algue à stocker l'azote et le phosphore dans ses tissus ont également été étudiées. D'autre part, un modèle de dynamique des populations a été conceptualisé puis développé. Les processus pris en compte dans ce modèle sont la croissance de l'algue (modèle à quota interne), la flottabilité de l'algue et la mortalité par surdensité. Ces processus ont été paramétrés en majeure partie par des expérimentations réalisées en laboratoire. Ce modèle 0D a par la suite était couplé au modèle hydrodynamique MARS3D (modèle Ifremer) mis en place sur la lagune de Salses-Leucate, utilisant deux grilles de calcul (160m ou de 80m de résolution). Les simulations réalisées permettent d'appréhender les capacités spatio-temporelles de la croissance de l'algue dans l'étang, le turnover annuel de la biomasse totale et les attracteurs de biomasse du système sous différents évènements météorologiques. Ces résultats sont comparés avec les répartitions cartographiques de la population observées in situ en 1999 et 2004 et des flux de biomasses mesurés au cours d'observations de terrain entre juin 2003 et septembre 2004. L'ensemble des résultats montre d'une part une adaptation de l'algue à évoluer dans un milieu pauvre en phosphore et d'autre part une croissance annuelle de la biomasse totale qui est principalement contrôlée par les apports hivernaux en sels nutritifs dans la lagune. Les résultats des simulations montrent également que V. aegagropila semble occuper à présent la majeure partie des zones favorables à sa croissance. Il est également montré que si sa capacité de mouvement peut favoriser la dispersion d'individus dans la lagune et accélérer la croissance de la population pour de faibles biomasses initiales, cette même capacité de mouvement joue plutôt un rôle de régulation de la population lorsque la biomasse totale devient importante. On peut penser que le risque de colonisation de l'herbier à zostère de la partie sud de la lagune (bassin de Salses) est limité. Ce travail ouvre enfin des perspectives de recherche sur l'amélioration du modèle de dynamique des populations de l'espèce, sur de nouvelles expérimentations à réaliser ou encore sur la surveillance écologique du milieu. Des propositions sont faites pour concevoir un modèle écologique confrontant les capacités physiologiques des macrophytes (algues vertes, Valonia et zostères) afin d'apréhender les phénomènes de compétitions et les modes de fonctionnement du réseau trophique de la lagune de Salses- Leucate. Des pistes sur la valorisation de la matière algale de V. aegagropila sont enfin proposées.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/these-2453.pdf
http://archimer.ifremer.fr/doc/00000/2453/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The 40Ar/39Ar geochronological technique has significantly contributed to the study of crustal deformation. However, the frequent occurrence of extraneous argon in high-pressure terrains can make the interpretation of 40Ar/39Ar ages problematic. This contribution attempts to: i) characterize the distribution and origin of extraneous argon in the Cycladic Blueschist Unit (CBU, Greece) by applying the 40Ar/39Ar dating technique on three Cycladic islands, Syros, Tinos and Ios, which span a complete transect of the CBU and ii) discuss regional implications for the tectonometamorphic evolution of the CBU. Our results, combined with ages available in the literature, show that periods of peak-burial conditions (55–49 Ma) and syn- (45–38 Ma) to post-orogenic exhumation (37–21 Ma) are well constrained in the CBU by the 40Ar/39Ar method. Moreover, Variscan apparent ages are preserved in the Cycladic basement of Ios, indicating that the 40Ar/39Ar system was not completely reset during the Eocene metamorphic episode. Additionally, our 40Ar/39Ar data show that the occurrence of extraneous argon is heterogeneously distributed in the CBU. While high-pressure rocks of Syros and Tinos are only locally affected, extraneous argon is clearly evidenced in the CBU of Ios, yielding geologically meaningless ages up to 900 Ma. On each island, the most affected ages were obtained in microstructures where fluid circulation is enhanced such as shear bands or strain shadows around garnets. We suggest that the Cycladic Basement, a polymetamorphic continental unit, behaved as an argon reservoir that has been mobilized by fluid circulation at the Eocene. These argon-enriched fluids have then heterogeneously contaminated metamorphic rocks when percolating through the CBU. Finally, we claim that a minimum closure temperature of 550 °C must be accepted for the phengites of the CBU and conclude that volume diffusion is not the main process resetting the argon isotopic system in high-pressure rocks compare to recrystallization enhanced by fluid circulation and deformation.
ISSN: 0024-4937

Droits : http://creativecommons.org/licenses/by-nc-nd/
insu-01424268
https://hal-insu.archives-ouvertes.fr/insu-01424268
https://hal-insu.archives-ouvertes.fr/insu-01424268/document
https://hal-insu.archives-ouvertes.fr/insu-01424268/file/Valentin-Lithos-Accepted-2016.pdf
DOI : 10.1016/j.lithos.2016.12.013

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
High-grade migmatitic and mylonitic gneisses from the Day Nui Con Voi massif in northern Vietnam record temperatures of 760-810 °C at pressures of 6-10 kbars. High temperature conditions have resulted in the development of major element diffusional profiles in garnet. Laser ablation ICP-MS analyses of trace elements indicate that REE and Hf closely followed Rayleigh-like fractionation trends but underwent significant post-crystallization modification. Light REE and to a lesser extent, HREE rim-to-rim zonation profiles show progressive flattening with the decreasing garnet size. Nd and Sm are completely homogenized in the crystals smaller than 1.5 mm, while Lu always preserves variable degrees of core-to-rim concentration gradient. The observed REE patterns are interpreted as resulting from the combination of protracted garnet growth of progressively smaller crystals and intracrystalline diffusion. This had profound influence on Sm-Nd geochronology and resulted in isochron ages ranging from 50 to 32 Ma. The youngest age was obtained for a sample, where all garnet crystals are smaller than 2 mm in which light REE profiles are completely or nearly completely homogenized. Thus, only the youngest age represents geologically meaningful event, and 31.7 ± 0.9 Ma age is interpreted as the best estimate of the resetting episode due to high temperature diffusional homogenization of light REE during early Oligocene metamorphism. Older Sm-Nd ages reflect mixed analyses of variably reset individual garnet crystals. Lu-Hf isotopic analyses of bulk garnet fractions, despite yielding high parent/daughter isotopic ratios appeared very scattered and did not allow defining isochron ages. Instead, apparent ages defined by whole rock and individual garnet fractions range from c. 80 to 160 Ma. Very old apparent ages are interpreted as being the consequence of intracrystalline Lu diffusion and preservation of the original Hf distribution, which leads to lower 176Lu/177Hf ratios, and thus steeper (older) isochrons. Back diffusion of Lu during commonly observed resorption played a subordinate role in modifying isotope systematics.
ISSN: 0009-2541

hal-00813949
https://hal.archives-ouvertes.fr/hal-00813949
DOI : 10.1016/j.chemgeo.2012.04.024

Éditeur(s) : HAL CCSD Institute of Electrical and Electronics Engineers
Résumé : International audience
: A new set-up for exposure of human cells in vitro at 37°C to pulse-modulated 300 MHz and 500 MHz signals of future magnetic resonance imaging (MRI) systems is designed, built up, and characterized. Two dipole antennas, specifically designed for ultra high field MRI, are used as radiating structures. The electromagnetic (EM) field distribution inside the incubator containing the cells is computed, and it is shown to be in a good agreement with measurements. The electric field at the cell level is quantified numerically. Local, 1g average, and averaged over the culture medium volume SAR are provided along with the standard deviation values for each well. Temperature increments are measured inside the culture medium during the exposure using an optical fiber thermometer. Then we identify the pulse parameters corresponding to the thermal threshold of 1°C, usually considered as a threshold for thermally-induced biological effects. For these parameters, the induction of heat shock proteins is assessed to biologically verify a potential thermal response of cells. The data demonstrate that, under the considered experimental conditions, exposure to pulsemodulated radiations emulating typical ultra high field MRI signals, corresponding to temperature increments below 1°C, does not trigger any heat shock response in human brain cells.
ISSN: 0018-9294

hal-00874329
https://hal.archives-ouvertes.fr/hal-00874329
DOI : 10.1109/TBME.2013.2270371
PUBMED : 23799680

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
Objectives: We propose a novel approach to examine vulnerability in the relationship between heat and years of life lost and apply to neighborhood social disparities in Montreal and Paris. Methods: We used historical data from the summers of 1990 through 2007 for Montreal and from 2004 through 2009 for Paris to estimate daily years of life lost social disparities (DYLLD), summarizing social inequalities across groups. We used Generalized Linear Models to separately estimate relative risks (RR) for DYLLD in association with daily mean temperatures in both cities. We used 30 climate scenarios of daily mean temperature to estimate future temperature distributions (2021-2050). We performed random effect meta-analyses to assess the impact of climate change by climate scenario for each city and compared the impact of climate change for the two cities using a meta-regression analysis. Results: We show that an increase in ambient temperature leads to an increase in social disparities in daily years of life lost. The impact of climate change on DYLLD attributable to temperature was of 2.06 (95% CI: 1.90, 2.25) in Montreal and 1.77 (95% CI: 1.61, 1.94) in Paris. The city explained a difference of 0.31 (95% CI: 0.14, 0.49) on the impact of climate change. Conclusion: We propose a new analytical approach for estimating vulnerability in the relationship between heat and health. Our results suggest that in Paris and Montreal, health disparities related to heat impacts exist today and will increase in the future
ISSN: 1660-4601

hal-01207279
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207279
DOI : 10.3390/ijerph120911869
PUBMED : 26402690

Éditeur(s) : HAL CCSD Wiley
Résumé : Tank bromeliads form a conspicuous, yet neglected freshwater habitat in Neotropical forests. Recent studies driven by interests in medical entomology, fundamental aspects of bromeliad ecology and experimental research on food webs have, however, prompted increasing interest in bromeliad aquatic ecosystems. As yet, there is nothing in the literature about the life histories and environmental drivers of invertebrate population dynamics in tank bromeliads. Based on fortnightly samples taken over oneyear, size frequency plots and individual dry masses allowed us to establish the life cycles and growth rates of the dominant aquatic invertebrates in a common bromeliad species of French Guiana. Linear mixed-effect models and Mantel tests were used to predict changes in density, biomass, and growth rates in relation to temperature, rainfall, humidity and detrital resources. Annual variations in invertebrate densities and biomasses could be described according to three types of distribution: unimodal, bimodal or almost constant. Despite seasonal variations, precipitation, temperature, relative humidity and detritus concentration accounted significantly for changes in density and biomass, but we found no significant responses in growth rates of most invertebrate species. Species rather displayed non-seasonal life cycles with overlapping cohorts throughout the year. There was also a trend for delayed abundance peaks among congeneric species sharing similar functional traits, suggesting temporal partitioning of available resources. Beyond novel knowledge, quantitative information on life histories is important to predict food-web dynamics under the influence of external forcing and self-organisation. Our results suggest that changes in species distribution that will affect population dynamics through biotic interactions in space and/or time could have greater effects on food webs and ecosystem functioning than changes in environmental factors per se.
ISSN: 0046-5070

hal-01607779
https://hal.archives-ouvertes.fr/hal-01607779
DOI : 10.1111/fwb.12862
PRODINRA : 407311

Éditeur(s) : Gauthier-Villars
Résumé : Pegasus current measurements carried out along a section located off French Guiana are presented; the section was repeated five times from September 1989 to June 1991 during the NOE (region Nord-Ouest equatoriale)/STACS (Sub Tropical Atlantic Climate Studies) cruises on board the NOAA (National Oceanographic and Atmospheric Administration) research vessels. The data (vertical and horizontal distributions) show, as suggested by earliest observations, the presence of different currents. At the surface, and in winter, the North Brazil Current (NBC) flows northwestward (positive), is strong (120 cm/s), confined in the first 250 m, coastally trapped (within 250 km) and fed by offshore waters; in summer the NBC strengthens (the velocity increases to 150 cm/s), vertically extends (down to 800 m) and veers offshore; the mean NBC mass flux computed from all the sections available is 34 +/- 9 Sv with absolute maximum and minimum respectively in September 1989 (81 +/- 4 Sv) and February 1990 (13 +/- 1 Sv). Subsurface, a southeastward (negative) undercurrent (herein after named Western Boundary UnderCurrent) is present in winter-spring and located in the layer 250-800 m with similar velocities in February 1990 (- 33 cm/s) and June 1991 (- 29 cm/s) but with largest vertical and horizontal extensions in the latter case; in summer (September 1989 and September 1990) this undercurrent is absent; the mean mTBUC mass flux is - 9 +/- 3 Sv; the maximum is observed in June 1991 (- 19 +/- 2 Sv) and the minimum in February 1990 (- 3 +/- 0.4 Sv) and January 1991 (- 5 +/- I Sv). Deeper, the equatorward Deep Western Boundary Current is trapped against the continental shelf (within 100 km of the shelf break), extends downward from 1 200 to 3 000 m depth with the velocity core centred in the 1 700-2 000 m layer, is maximum (- 50 cm/s) in spring-summer and minimum (- 23 cm/s) in winter; the absolute velocity (- 92 cm/s) has been recorded at 2 000 m depth in September 1989 suggesting a strong variability at this level; the mean equatorward DWBC mass flux is - 30 +/- 14 Sv with absolute maximum and minimum respectively in September 1989 (- 59 +/- 6 Sv) and September 1990 (- 7 +/- 1 Sv). The Integrated Mass, Temperature and Salt Fluxes (IMF, ITF and ISF) with the cumulated errors, computed across the whole section and down to 3 000 m depth for the September 1990, January 1991 and June 1991 cruises, are all positive in September 1990 (respectively 1.9 +/- 19 Sv, 3.1 +/- 30.1 PW and 74 +/- 1 845 Tt/s) but all negative both in January 1991 (- 13.3 +/- 17.0 Sv, - 15.6 +/- 26.5 PW and - 478 +/- 1594 Tt/s) and June 1991 (- 3.8 +/- 10.1 Sv, - 4.0 +/- 16.3 PW, - 130 +/- 989 Tt/s) showing a strong variability between the summer and winter periods. The mean IMF, ITF and ISF values (respectively - 5.1 +/- 46.4 Sv, - 5.2 +/- 73 PW and - 178 +/- 4428 Tt/s) are high and negative, indicating the large influence of the DWBC and the associated North Atlantic Deep Water (upper part) off French Guiana at 5 degrees N.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 2 , P. 143-157

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00098/20881/18495.pdf
http://archimer.ifremer.fr/doc/00098/20881/

Éditeur(s) : HAL CCSD
Résumé : International audience
The aim of this study is to suggest two automated techniques able to help medical staff to detect earlier than usual some diseases using wireless sensor networks (WSNs). In this context, a patient is equipped with physical sensors (for temperature, pressure, ..). This WSN will perform some computations and will run an alarm when a disease is suspected. The first technique uses a population protocol to handle data exchanged between motes and provides an efficient algorithm to suggest that a disease is diagnosed on a patient. The algorithm is distributed, i.e., the decision may be done by any mote dealing with the disease detection. The second technique uses a token algorithm where, some motes, denoted as masters. Each of them is in charge of deciding if a specific disease occurs. This technique is not totally distributed but enhances the network efficiency regarding to the energy consumption, the time execution and the number of exchanged messages.
Proceedings of The Ninth IEEE International Symposium on Networking Computing and Applications
Cambridge, MA, United States

hal-00519599
https://hal.archives-ouvertes.fr/hal-00519599

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes1. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre2, 3. At temperatures above 300–450 degrees Celsius, usually found at depths greater than 10–15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional–mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades4, 5. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.
ISSN: 0028-0836

hal-01685757
https://hal.archives-ouvertes.fr/hal-01685757
DOI : 10.1038/nature22355

Éditeur(s) : HAL CCSD
Résumé : International audience
In this paper, we focus on providing new tools to help doctors in their diagnosis. We study the feasibility of using a distributed approach over Wireless Sensor Networks (WSN). We define a Wireless Body Area Network (WBAN) as a set of wireless sensors which equipped a patient. Each sensor senses a health parameter, for example, temperature or heart pulse. Our aim is to understand how a distributed approach can be a fair alternative to the common centralized paradigm. We study a distributed approach based on the token paradigm. Then, we compare this approach to the centralized one, throw simulations and experimentations over real sensors.
11th International Conference on Innovative Internet Community Systems

hal-00602207
https://hal.archives-ouvertes.fr/hal-00602207

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
To understand the deep cycle of water, upper mantle water content and distribution between nominally anhydrous minerals (NAMs) and hydrous minerals (e.g., amphibole) must be constrained. We need then to understand H behaviour during mantle melting and metasomatism. Major, minor and trace element compositions including water contents were obtained on ten xenoliths of spinel-bearing peridotites from the Ray Pic locality, in the Southern part of the Massif Central (France). The sample suite investigated here is composed of rather fertile lherzolites (89.4 ≤ Fo ≤ 90.8%; 11.3 ≤ cr# in spinel ≤ 21.1%; 0.942 ≤ [Yb]cpx ≤ 1.90 ppm; cpx: clinopyroxene), which can be best explained by batch melting, with degree of melting between 3 and 10%. These xenoliths contain up to 8% modal amphibole. Three groups are defined as a function of the amphibole modal abundance (above or below 1%) and equilibrium temperature (above or below 1000 °C). Results show no clear positive correlation between modal metasomatism (amphibole) and incompatible element enrichment in cpx. Trace element compositions in cpx show strong enrichments of the most incompatible elements (e.g., (La/Sm)PM as high as 15.7; PM: normalised to primitive mantle values), but strong negative anomalies of the high field strength elements (e.g., (Th/Nb)PM as high as ~ 680). Such trace element fractionations are usually ascribed to the so-called carbonatitic metasomatism involving the percolation of small volume melts which are enriched in volatiles. The hydrogen concentrations in cpx range from 203 to 330 ppm wt. H2O, in orthopyroxene from 66 to 160 ppm wt. H2O and in olivine from 2 to 6 ppm wt. H2O. These values are within the common concentration range of other spinel-bearing peridotites. Amphiboles contain 1.9 ± 0.5 wt.% of H2O.The effect of metasomatism on water abundances in NAMs is not straightforward. Hydrous metasomatism (i.e., leading to the crystallisation of OH-bearing amphibole) has no effect on the water content of the co-existing NAMs. This suggests thus that the occurrence of hydrous minerals, such as amphibole, does not systematically imply that the coexisting NAMs are water-rich (saturated). Further, the percolation of volatile-rich small volume melts, which is fingerprinted by the strong enrichment of the incompatible elements, has also no clear effect on the water content of the NAMs. These data are thus difficult to reconcile with the admitted highly incompatible behaviour of H in upper mantle minerals.
ISSN: 0024-4937

hal-01278062
https://hal.archives-ouvertes.fr/hal-01278062
DOI : 10.1016/j.lithos.2015.08.013

Éditeur(s) : Mercator Ocean
Résumé : Face to the lack of data to assess precisely the spatial distribution of catches and fishing effort and for the environmental characterization of the fishing area, Ifremer has been implemented since 2005 a new project, Recopesca. It consists in fitting out a sample of voluntary fishing vessels with sensors recording data on fishing effort (and at mid-terms catches) and physical parameters such as temperature or salinity. Recopesca aims at setting up a network of sensors, for scientific purposes, to collect data and improve resources assessment and diagnostics on fisheries, and environmental data required for ecosystem-based management initiatives. The challenge was to develop sensors with no trouble for the fishermen, tough enough to be fixed up on fishing gears, self powered and autonomous. Insofar as the sample of targeted vessels intends to be representative of all the metiers and fleets, the sensors are modular and scalable to collect new data. Different sensors have been implemented: (i) a temperature-salinity sensor, able to record physical parameters, depth and duration of immersion, for passive and active gears, and (ii) a specific sensor to record number or length of passive gears. A GPS monitors the position of the vessels and the temperature or salinity profiles and series. Each sensor is equipped with a radio device transferring the data to a receiver on-board, called “concentrator” that sends the data to Ifremer central databases by GPRS. An anti-rolling weigh-scale has been developed and is currently on test to record catches per species and fishing operation. The presentation will show the first data and results of this participative approach.
Mercator Ocean - Quarterly Newsletter (Mercator Ocean), 2010-04 , N. 37 , P. 40-48

Droits : 2010 Mercator Ocean
http://archimer.ifremer.fr/doc/00024/13500/10514.pdf
http://archimer.ifremer.fr/doc/00024/13500/

Éditeur(s) : Gauthier-Villars
Résumé : Long tropical instability waves are described at around 3-4 degrees N based on results of a simulation performed with a general circulation model for the Atlantic Ocean. This description is in agreement with earlier observations of organized undulations of the summer thermal front associated with anti-cyclonic eddies propagating westward at 30-40 km/day along 3-4 degrees N from 10 to 40 degrees W through the Atlantic basin. However, the simulation indicated the presence of long waves in early boreal winter. In this respect, satellite observations during short cold events in winter show thermal front undulations similar to those associated with long wave propagations. The simulation clearly demonstrated large vertical movements between the surface and a depth of 70 m, associated with anti-cyclonic eddies at around 3 degrees N. These vertical movements could commonly reach the thermocline in the central part of the Atlantic basin (10-20 degrees W). In this region, long instability waves could subsequently affect biological production by ''eddy pumping''. During the PIRAL cruise at 4 degrees N-20 degrees W in June 1986, remarkably high chlorophyll concentrations (the highest values in our data bank for the equatorial Atlantic and typical of a very productive zone) were associated with currents similar to those of an anticyclonic eddy and characterized by a surface temperature distribution typical of the long instability wave pattern. These high chlorophyll concentrations may have resulted from ''eddy pumping'' and/or strong meridian advection since each of these mechanisms is associated with long instability waves.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 6 , P. 585-596

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00099/21034/18660.pdf
http://archimer.ifremer.fr/doc/00099/21034/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Orogenic lherzolites exhibit a specific (although reproducible) platinum-group element signature characterized by slight positive deviations of Pd/Ir, Rh/Ir and Ru/Ir ratios from the canonical chondritic model. Such a signature was alternatively considered to be a compositional feature of the primitive upper mantle or resulting from sulfide melt addition by refertilisation reactions in the continental lithosphere. To shed additional light on this conundrum, the distribution of PGE in FON B 93, an unserpentinized, fertile (3.24% Al2O3) orogenic lherzolite (French Pyrenees) used as in-house standard by our group, has been studied to different scales, from the bulk rock to trace minerals. In addition to new ICPMS analyses after separation into Nis and Te coprecipitation, its whole-rock PGE concentrations were redetermined by three different laboratories using very precise ID-ICP-MS methods after digestion of the sample in Carius tube at T=250 degrees C and 320 degrees C or in high-pressure asher (HPA-S). The four methods produce reproducible Ru, Rh and Pd contents (7.1 +/- 0.18 ppb; 1.43 +/- 0.05 ppb; 7.1 +/- 0.30 ppb) whereas the non-ID NiS-fire assay method underestimates the Os and Ir concentrations by c.a. 10 and 15% compared to ID-ICP-MS analyses (4.40 +/- 0.07 and 4.00 +/- 0.17 ppb, respectively). Platinum was the most difficult to analyse. If performed on powder aliquots smaller than 3 g, the ID-ICP-MS analyses generate strong nugget effects while the non-ID NiS-fire assay method yields statistically lower (but highly reproducible) Pt concentrations (6.92 +/- 0.26 ppb). These features reflect the strong partitioning of Pt into trace phases that SEM and laser ablation-ICP-MS analyses on thin sections identify as both high-temperature Pt-Ir-Os alloys and Pt-(Pd) tellurides of likely subsolidus origin; ten to fifteen grains ranging in maximum dimension from a few micrometres to a few hundreds of nanometers, were identified by standard polished thin section. LA-ICP-MS data on base metal sulfides (25 grains analysed), coupled with the whole-rock S concentration (277 +/- 10 ppm) and modal composition of the BMS (90% pentlandite+accessory pyrite and secondary pyrrhotite + 10% chalcopyrite) allowed the contribution of the BMS phase to the PGE budget of FON B 93 to be estimated. Except Pt that exhibits a 95% deficit in the BMS phase, the PGE concentrations measured by ID-ICP-MS can be balanced by BMS while Al-spinel is a negligible contributor, accounting for less than 0.5% of the Ru budget. The occurrence of Pt in trace phases may bias the whole-rock Pt concentrations because 1) mechanical collection of Pt-rich trace phases remains problematic with the Nis button, and 2) Pt-Ir-Os alloys may be prone to digestion problems in conventional Carius tube procedures. Since they could be stable at mantle depth, such refractory alloys that contain Os and Ir may also have enhanced the heavy PGEs/light PGEs fractionation. Our observations likely pertain to orogenic lherzolites as a whole because BMS assemblages in these mantle rocks record evolution at low sulfur fugacity, which prevents Pt-Ir-Os alloy from entering the Mss in the mantle; moreover, at subsolidus temperature, pentlandite, the major BMS, cannot accommodate 0 valence state Pt.
ISSN: 0009-2541

hal-00411486
https://hal.archives-ouvertes.fr/hal-00411486
DOI : 10.1016/j.chemgeo.2007.06.030

Éditeur(s) : HAL CCSD
Résumé : 15 pages
International audience
In analogy to the classical isomorphism between $mathcal{L}left( mathcal{S}left( mathbb{R}^{n}right) ,mathcal{S}^{prime}left( mathbb{R}^{m}right) right) $ and $mathcal{S}^{prime}left( mathbb{R}^{n+m}right) $, we show that a large class of moderate linear mappings acting between the space $mathcal{G}_{mathcal{S}}left( mathbb{R}^{n}right) $ of Colombeau rapidly decreasing generalized functions and the space $mathcal{G}_{ au}left( mathbb{R}^{n}right) $ of temperate ones admits generalized integral representations, with kernels belonging to $mathcal{G}_{ au}left( mathbb{R}^{n+m}right) $. Furthermore, this result contains the classical one in the sense of the generalized distribution equality.
Math. Proc. Camb. Philos. Soc.

Droits : info:eu-repo/semantics/OpenAccess
hal-00019916
https://hal.archives-ouvertes.fr/hal-00019916
https://hal.archives-ouvertes.fr/hal-00019916/document
https://hal.archives-ouvertes.fr/hal-00019916/file/KernelSADelcroixfeb7th.pdf
ARXIV : math.FA/0603035

Éditeur(s) : HAL CCSD
Résumé : Water vapour is highly variable in the atmosphere with concentration reaching saturation in the tropics and with dry areas over elevated continental region. Good knowledge of the amount of integrated water vapour in the air is necessary to predict phase changes and in particular precipitation. Water vapour variability measurements are still insufficient with standard observing systems. Moreover accurate GPS antenna positioning is affected by the refractivity index variation in the troposphere. Consequently, vertical positioning component estimation is difficult. This variation is directly linked to distribution of variables such as pressure, temperature and humidity along the path between satellite and receiver. Here we study more specifically heavy rains et notably Cevenols events. This thesis work consists to check the GPS measurement validity to quantify water vapour in comparison with measurements from radiosoundings and meteorological model outputs. GPS observations and flux surface information have been analysed to see if water vapour quantification by GPS allowed characterising heavy rain events (cumulative rainfall amount greater than 150 mm). Then, we tested the GPS data assimilation impact on cumulative precipitation forecasts using the high resolution Meteo France AROME model (2.5 km). Finally the quality and the contribution of GPS measurement on sea is evaluated for water vapour measurement. This study has been realised in the framework of VAPIMED experiment.
La vapeur d'eau varie largement dans l'atmosphère avec des concentrations allant de la saturation dans les tropiques à des zones presque sèches au-dessus des zones continentales élevées. Une bonne connaissance du contenu en vapeur d'eau dans l'air est nécessaire pour la prévision des changements de phases, notamment les précipitations. La mesure de la variabilité de la vapeur d'eau est une lacune des systèmes d'observation. Par ailleurs, il est apparu que le positionnement précis des antennes GPS était affecté par la variation de l'indice de réfraction dans la troposphère, ce qui rend particulièrement difficile l'estimation de la composante verticale. Cette variation est directement liée à la distribution des variables pression, température et humidité sur les trajets satellite-récepteur. On s'intéresse ici à l'étude des précipitations intenses et notamment aux épisodes Cévenols. Ce travail de thèse consiste à vérifier la validité de la mesure GPS pour la quantification de la vapeur d'eau en la comparant avec des mesures issues de radiosondage et des sorties de modèle météorologique. On cherche à analyser si la quantification de vapeur d'eau par GPS permet de caractériser les forts événements précipitants (cumuls supérieurs à 150 mm) à l'aide d'observations conjointes sur les flux de surface. On étudie ensuite l'impact de l'assimilation de données GPS issues d'un réseau GPS dense sur la prévision des cumuls de pluies dans le modèle à hauterésolution (2.5 km) AROME de Météo France. Finalement on évalue la qualité et l'apport de la mesure de vapeur d'eau par GPS en mer dans le cadre d'une campagne de mesure VAPIMED).
https://tel.archives-ouvertes.fr/tel-00444081

Droits : info:eu-repo/semantics/OpenAccess
tel-00444081
https://tel.archives-ouvertes.fr/tel-00444081
https://tel.archives-ouvertes.fr/tel-00444081/document
https://tel.archives-ouvertes.fr/tel-00444081/file/These_KBoniface.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
In this work, we have led an analysis of the error of different global solar radiation prediction models according to the global solar radiation variability. Different predictions models where performed such as machine learning techniques (Neural Networks, Gaussian processes and support vector machines) in order to forecast the Global Horizontal solar Irradiance (GHI). We also include in this study a simple linear autoregressive (AR) model as well as two naive models based on persistence of the GHI and persistence of the clear sky index (denoted herein scaled persistence model). The models are calibrated and tested with data from three 3 French islands: Corsica (42.15°N ; 9.08°E), Guadeloupe (16.25°N ; 61.58°W) and Reunion (21.15°S ; 55.5°E). Guadeloupe and Reunion are located in a subtropical climatic zone whereas Corsica is in a tempered climatic zone. Hence the global solar radiation variation differs significantly. The output error of the different models was quantified by the nRSME. In order to quantify the influence of the global solar radiation variability on the forecasting models error we performed a classification of typical days according to different typical days. Each class of typical day is defined by a variation of global solar radiation rate. For each class and for each location, the selected forecasting models where performed and the error was quantified. With this analysis a global solar radiation forecasting models can be selected according to the location, the global solar radiation fluctuations and hence the meteorological conditions. INTRODUCTION Large and frequent variations of solar radiation can be observed in tropical climates with amplitudes reaching 800 W/m² and occurring within a short time interval, from few seconds to few minutes, according to the geographical location. Such fluctuations can be due for example to the dynamic of clouds which can be very complex and depend on cloud type, size, speed and spatial distribution and, more generally, due to some specific local meteorological conditions. Thus, the solar energy forecasting, a process used to predict the amount of solar energy available in the current and near terms, might be a difficult task. Some of the best predictors found in literature are Autoregressive and moving average (ARMA) [5,7,8], Bayesian inferences [9,10], Markov chains [11], k-Nearest-Neighbors predictors [12] or artificial intelligence techniques as the Artificial Neural Network (ANN) [9-11]. Although these methodologies are potentially good in many areas, we observed in our previous studies on global radiation prediction [9,13,14] that the simple model based on the persistence of the clear sky index gives often very good results with acceptable errors [15] for short term forecasting time horizon (<= 1 hour). The goal of this paper is to determinate the influence of solar radiation variability regarding different classes of days on the expected error provided by different forecasting methods that the modeller can possibly implement. The paper is organized as follow: Section 2 describes the data we have used. Section 3 exposes the classification methodology and the results obtained for the three studied locations. In the two following sections, the forecasting methods are exposed and then 3 the errors on the forecasting results for each location and for each class are exposed.
The Third Southern African Solar Energy Conference (SASEC2015)
Kruger National Park, South Africa

Droits : info:eu-repo/semantics/OpenAccess
hal-01099487
https://hal.archives-ouvertes.fr/hal-01099487
https://hal.archives-ouvertes.fr/hal-01099487/document
https://hal.archives-ouvertes.fr/hal-01099487/file/article%20SASEC.pdf

Éditeur(s) : HAL CCSD American Meteorological Society
Résumé : Global positioning system (GPS) data from a dense network have been used for the analysis of the diurnal cycle of water vapor over Marseille, France, during the second intensive observation period (IOP2; 21–26 June 2001) of the Expérience sur Sites pour Contraindre les Modèles de Pollution Atmosphérique et de Transport d'Emission (ESCOMPTE) field experiment. Both tomographic analyses and integrated water vapor (IWV) contents from GPS have been used, in addition to wind profiler data and surface observations. Tomographic analysis of data from the dense GPS network and radiosondes provided the continuous temporal evolution of the vertical distribution of water vapor over the city of Marseille. The city is located on the shore of the Mediterranean Sea in southeastern France and is often under the influence of sea-breeze effects. Two different layers of breeze circulation are identified: a shallow sea breeze, blowing perpendicular to the local coastline, and a deep sea breeze, induced by the regional temperature gradient between sea and land. The origin of water vapor is shown to be mainly due to the advection of marine moist air by these sea-breeze circulations. However, the diurnal cycle of water vapor over Marseille is strongly influenced by the synoptic situation, which changes during the IOP2 (between a northerly mistral in the early stage of the IOP and an easterly wind at the end). It is shown that vertical profiles from tomographic analyses (combined with wind profiler data) allow for a proper interpretation of the diurnal cycle observed in IWV. Two-dimensional maps of IWV are also shown to complement the description of the horizontal advection of moisture by the different circulation regimes.
ISSN: 1558-8424

hal-00273624
https://hal.archives-ouvertes.fr/hal-00273624
https://hal.archives-ouvertes.fr/hal-00273624/document
https://hal.archives-ouvertes.fr/hal-00273624/file/drJAM_cycle_diurne_GPS_rev1.pdf
DOI : 10.1175/JAM2450.1

Éditeur(s) : Proceedings of the 59th Annual Gulf and Caribbean Fisheries Institute
Résumé : In most of marine fishes cultured, larvae in their early development are fed with live prey (rotifer and/or artemia). In hatcheries, culture of these preys is labour consuming, needs specific facilities and represent an important part of production cast. On the other hand, world artemia production is subjected to fluctuation of harvest in the wild which could Iimit fish farming industry in the near future. A dried formula adapted to marine fish larvae has been perfected by Ifremer's center of Brest (France) and is distributed by a feeding company since 1999. This artificial microbound diet has been successfully tested on several temperate fishes such as European seabass (Dicentrarchus labrax), Atlantic cod (Gadus morhua) or European seabream (Sparus aurata) in a co-feeding (i.e. artemia and dried diet) strategy. Experiments described here were carried out ta evaluate the performances obtained during total substitution of artemia by this diet in Red drum (Sciaenops ocellatus) larval culture. ln 2004 and 2005, four experiments were conducted on feed technology aspects (experimental or industrial manufacturing), weaning strategy (direct or co-feeding) and feed distribution method (prototypes or classical self feeder) in comparison to the standardized method using live preys. At the end of larval phase (day 15) and at day 30, end of nursery phase (0.6 g), survival relative to control (RTC) was respectively 96.9% and 111.0% in the best treatment. Concerning growth, the weight RTC reached at day 15 and day 30 was respectively 82.8% and 72.4%. However, it is important to note that rearing protocols have to be adapted ta the use of these micro pellets in order toprevent degradation of culture quality. These results show that this new product can be applied on industrial scale in private hatcheries. But further research is needed ta evaluate replacement of rotifers by this dried formula in order to completely eliminate live prey in larval culture of Red drum.
Dans la plupart des poisons marins élevés, les larves sont nourries avec des proies vivantes (rotifères et/ou artémia) au début de leur développement. Dans les écloseries, la culture de ces proies est consommatrice de main d'oeuvre, nécessite des installations spécifiques et entre pour une part importante dans le coût de production. Par ailleurs, la production mondiale d'artémia est dépendante de la fluctuation des récoltes dans le milieu naturel, ce qui pourrait gêner la filière piscicole marine dans un futur proche. Une formulation alimentaire inerte adaptée aux larves de poisson marin a été mise au point par le centre Ifremer de Brest (France) et est commercialisée par un provendier depuis 1999. Ces microparticules artificielles ont été testée avec succès sur plusieurs poissons tempérés comme le bar européen (Dicentrarchus labrax), la morue atlantique (Gadus morha) ou la daurade européenne (Sparus aurata) dans un contexte de co-feeding (i.e. artémia et aliment inerte). Les expériences décrites ici ont été menées afin d'évaluer les performances obtenues lors de la substitution totale des artémia par cet aliment dans l'élevage larvaire de l'ombrine (Sciaenops ocellatus). En 2004 et 2005, quatre expériences ont été menées sur l'aspect technologie alimentaire (fabrication expérimentale ou industrielle), la stratégie de sevrage (direct ou co-feeding) et le mode de distribution de l'aliment (distributeur classique ou prototypes) en comparaison au standard sur proies vivantes. En fin de phase larvaire (jour 15) et au jour 30 après une phase de prégrossissement (0.6g), la survie par rapport au témoin (RTC) était respectivement de 96.9% et 111 .1% dans le meilleur traitement. Concernant la croissance, les poids obtenus aux jours 15 et 30 atteignaient respectivement 82.8% et 72.4%. Cependant il est important de relever que les protocoles d'élevage doivent être adaptés à l'utilisation de ces microparticules afin de prévenir une dégradation de la qualité d'élevage. Ces résultats montrent que ce nouveau produit peut être appliqué à l'échelle industrielle dans les écloseries privées. Cependant, les recherches doivent être poursuivies pour évaluer les possibilités de remplacement des rotifères par ces aliments inertes afin de s'affranchir complètement de l'utilisation de proies vivantes dans l'élevage larvaire de l'ombrine.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/acte-6597.pdf
http://archimer.ifremer.fr/doc/00000/6597/

Éditeur(s) : HAL CCSD
Résumé : International audience
The most active deep convection area in the western Mediterranean Sea is located in the Gulf of Lions. Recent studies in this area provides some insights on the complexity of the physical dynamics of convective regions, but very little is known about their impacts on the biogeochemical properties. The CASCADE (CAscading, Surge, Convection, Advection and Downwelling Events) cruise, planed in winter 2011, give us the opportunity to compare vertical profiles of properties sampled either during stratified conditions or after/during a convection event. In the present study, we focus on the distributions of the carbonate system properties (mainly total alkalinity, AT; and total dissolved inorganic carbon, CT) because, in the context of the climate change, deep convection areas are suspected to significantly increase the sequestration of anthropogenic CO2 (CANT). Given its limited size, the impact of the Mediterranean Sea on the global carbon budget is probably minor but this marginal sea can be used as a laboratory to better understand carbon sequestration and its transfer to the basin interior by deep convection processes. Distributions of AT and CT, both measured from bottle samples, and that of CANT (estimated with the TrOCA approach) are first analyzed in the light of other key properties (salinity, temperature, and dissolved oxygen). An objective interpolation procedure is then applied to estimate CT and AT from CTD measured properties. With this procedure, the vertical resolution goes from a maximum of 32 samples per station to one property estimate every meter (more detailed distributions are obtained). Results provide arguments to conclude that CANT is rapidly transferred to the deepest layer due to deep convection events. During deep convection events, the increase of CANT in the water column is positively correlated to that of potential density and oxygen content. The challenge of quantifying the amount of sequestered carbon is however not resolved due to the complexity and the highly dynamical nature of the convective regions. Deep convection in the Gulf of Lions, in parallel with cascading along the continental slope, could thus potentially explain the very high levels of both CANT and acidification estimated in the deep layers of the western Mediterranean Sea.
Deep Sea Research Part I: Oceanographic Research Papers

hal-01336725
https://hal-univ-perp.archives-ouvertes.fr/hal-01336725
DOI : 10.1016/j.dsr.2016.04.003