Evolución estacional del patrón de nutrientes sobre la plataforma continental del golfo de Vizcaya durante los años 1999-2000

The French Atlantic shelf is subjected to strong anthropic influences (urban, industrial and agricultural discharges) of two main rivers (Loire and Gironde). The extension and consequences of these continental loadings for the nutrient and chlorophyll distribution have never been studied before on the Bay of Biscay continental shelf as a whole. We present the first synoptic view of the nutrient distribution and evolution on the French Atlantic shelf. Nutrient concentrations of the surface layer were studied during four cruises in April, June, September 1999 and March 2000. Until June, the freshwater inputs induce a nitrate gradient from river mouths to offshore waters in the vicinity of the 100 m isobath. The Redfield’s ratio study highlights the nitrate excess in river loadings. The early spring situation is characterised by high N:P ratios in front of the two estuaries and by a potential Si-limitation in the northern part. Nitrate removal continues in spite of the P-limitation and the increase in silicate concentrations during summer supposes high regeneration processes. At the end of summer, the water column is thermally stratified and the surface mixed layer is totally depleted in nitrate.La zona de plataforma del Atlántico francés está sujeta a una fuerte influencia antropogénica (urbana, industrial, descargas de la agricultura) principalmente de dos rios (Loire y Gironde). La extensión y consecuencias de tales descargas continentales sobre la distribución de nutrientes y clorofila, no ha sido todavía estudiada en la totalidad de la plataforma continental del golfo de Vizcaya. Aquí presentamos una visión sinóptica de la distribución y evolución de nutrientes sobre la plataforma del Atlántico francés. Las concentraciones de nutrientes de las capas superficiales han sido estudiadas durante 4 campañas en abril, junio, septiembre de 1999 y marzo de 2000. Hasta junio, los aportes de agua dulce inducen a un gradiente de nitratos desde la desembocadura del río hasta las aguas oceánicas en la vecindad de la isobata de 100 m. La determinación del cociente de Redfield evidencia una descarga del río con exceso de nitrato. La situación de principios de primavera está caracterizada por un cociente alto de N:P en contraste con los dos estuarios y por una potencial limitación de Si en la parte norte. La eliminación de nitrato que tiene lugar, a pesar de la limitación de fósforo y el incremento de la concentración de Si durante el verano, supone procesos de alta regeneración. Al final del verano, la columna de agua está termicamente estratificada y la superficie de la capa de mezcla está totalmente agotada de nitrato

Influence de l'arrangement granulaire d'un sédiment polydisperses sur le seuil de mise en mouvement

La prédiction du transport d'un mélange de particules de plusieurs tailles est un point sensible d'une représentation de la dynamique sédimentaire sur de nombreux faciès en rivière ou en mer. Afin de déterminer les processus critiques qui régissent la mise en mouvement de tels mélanges et de quantifier leur contributions, des essais ont été réalisés dans un petit canal à courant. Ils ont porté sur des échantillons reconstitués, formés de sables naturels lithoclastiques bien triés ou de mélanges sableux bimodaux. L'objectif est d'observer et de quantifier les différences de comportement à l'entrainement entre un sédiment unimodal et un sédiment mélangé. Les résultats obtenus sont comparés à une sélection de formulations issues de la littérature. La série de tests a permis de mettre en évidence quelques processus particuliers du début du transport sédimentaire multiclasse dans un écoulement stationnaire. La granulométrie utilisée s'étend des sables fins aux sables très grossiers. Des paramètres du mélange tels que le rapport de taille des particules, le taux de saturation des échantillons par les grains dont la taille est la plus fine ou la porosité influent sur la modulation de la contrainte de frottement critique. Les comparaisons mesures / formules ont mis en évidence la difficulté de prédire le seuil de mise en mouvement des particules d'un mélange hétérométrique. Par conséquent, l'incertitude sur la granulométrie transportée s'accroît lorsque le frottement est proche du frottement critique d'une certaine classe de taille

Second primary squamous cell carcinoma arising in cutaneous flap reconstructions of two head and neck cancer patients

Early complications of myocutaneous flap transfers following surgical eradication of head and neck tumors have been extensively described. However, knowledge concerning long-term complications of these techniques remains limited. We report the cases of two patients with a prior history of squamous cell carcinoma of the head and neck (HNSCC), who developed a second primary SCC on the cutaneous surface of their flaps, years after reconstruction. Interestingly, it seems that the well-known risk of a second primary SCC in patients with previous head and neck carcinoma also applies to foreign tissues implanted within the area at risk. Given the important expansion of these interventions, this type of complication may become more frequent in the future. Therefore, long-term follow-up of patients previously treated for HNSCC not only requires careful evaluation of the normal mucosa of the upper aero-digestive tract, but also of the cutaneous surface of the flap used for reconstruction

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution

Accretion, structure and hydrology of intermediate spreading-rate oceanic crust from drillhole experiments and seafloor observations

Downhole measurements recorded in the context of the Ocean Drilling Program in Hole 504B, the deepest hole drilled yet into the oceanic crust, are analyzed in terms of accretion processes of the upper oceanic crust at intermediate spreading-rate. The upper part of the crust is found to support the non steady-state models of crustal accretion developed from seafloor observations (Kappel and Ryan, 1986; Gente, 1987). The continuous and vertical nature of borehole measurements provides stratigraphic and structural data that cannot be obtained solely from seafloor studies and, in turn, these models define a framework to analyze the structural, hydrological, and mineralogical observations made in the hole over the past decade.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43190/1/11001_2005_Article_BF01204282.pd

Représentations des adolescentes en matière de contraception (étude qualitative par focus group dans le nord Finistère)

Après avoir présenté les modèles physiologiques, sociologiques, psychologique et psychanalytiques des adolescentes, les particularités de leurs sexualités puis de leur moyens de contraception, l'auteur cherche à comprendre quelles seraient les attentes des adolescentes en matière de contraception en soin primaire. Il réalise un étude qualitative par cinq focus group chez des adolescentes de 15-19 ans recrutées par volontariat dans des lycées du nord Finistère. Il conclut en faisant part de représentation paternaliste du médecin de famille , d'un manque de confiance dans le secret médical ou dans la formation reçue, même si les adolescentes interrogées gardent une vision de proximité, de confiance en leur médecin généraliste. La tâche des professionnels de santé serait peut être donc d'aborder plus systématiquement le sujet de la sexualité et de la contraception lors des consultations.BREST-BU Médecine-Odontologie (290192102) / SudocSudocFranceF

In vitro effect of hydrostatic pressure exposure on hydroxyl radical production in fish red muscle.

International audienceThe effects of hydrostatic pressure on reactive oxygen species (ROS) production have been studied in vitro on fish red muscle fibres. In the eel, Anguilla anguilla, previous studies have shown that hydrostatic pressure acclimatization improves oxidative phosphorylation efficiency together with a supposed concomitant decrease in electron leak and ROS production. In order to test the hypothesis of an electron leak decrease under pressure, hydroxyl radical (HO*) production and oxygen consumption were measured on fish red muscle fibres directly exposed to hydrostatic pressure. Experiments were performed under two conditions--atmospheric pressure and hydrostatic pressure (16.1 MPa)--on eel and trout (which exhibit low- and high-pressure sensitivity, respectively). This work has permitted, first, the validation of an indirect HO* measurement (in vitro) on fish red muscle and the documentation of reference values for fish. Second, at atmospheric pressure, results show higher oxygen consumption for trout (+40%) than for eel which is accompanied by higher HO* production (+90%); in addition, both species present a positive relationship between HO* production and oxygen consumption. Hydrostatic pressure exposure reverses this relationship for eel but not for trout. These preliminary results only partially verify the proposed hypothesis and further experiments are needed