821 research outputs found

    Note sur quelques foraminifères du Strunien et du Dinantien d'Europe Occidentale

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    Description of new Dinantian Foraminifers: Earlandiidae, Tournayellidae, Endothyridae and Loeblichiidae. Emendations and corrections relating to Archaediscidae, Endothyridae and Tournayellidae

    Morphological analysis of stylolites for paleostress estimation in limestones surrounding the Andra Underground Research Laboratory site

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    We develop and test a methodology to infer paleostress from the morphology of stylolites within borehole cores. This non-destructive method is based on the analysis of the stylolite trace along the outer cylindrical surface of the cores. It relies on an automatic digitization of high-resolution photographs and on the spatial Fourier spectrum analysis of the stylolite traces. We test and show, on both synthetic and natural examples, that the information from this outer cylindrical surface is equivalent to the one obtained from the destructive planar sections traditionally used. The assessment of paleostress from the stylolite morphology analysis is made using a recent theoretical model, which links the morphological properties to the physical processes acting during stylolite evolution. This model shows that two scaling regimes are to be expected for the stylolite height power spectrum, separated by a cross-over length that depends on the magnitude of the paleostress during formation. We develop a non linear fit method to automatically extract the cross-over lengths from the digitized stylolite profiles. Results on cores from boreholes drilled in the surroundings of the Andra Underground Research Laboratory located at Bure, France, show that different groups of sedimentary stylolites can be distinguished, and correspond to different estimated vertical paleostress values. For the Oxfordian formation, one group of stylolites indicate a paleostress of around 10 MPa, while another group yields 15 MPa. For the Dogger formation, two stylolites indicate a paleostress of around 10 MPa, while others appear to have stopped growing at paleostresses between 30 and 22 MPa, starting at an erosion phase that initiated in the late Cretaceous and continues today. This method has a high potential for further applications on reservoirs or other geological contexts where stylolites are present.Comment: International Journal of Rock Mechanics and Mining Sciences (2013) online firs

    Prevalencia del consumo de tabaco, grado de dependencia y estilo de vida de los estudiantes del Campus Universitario Duques de Soria

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    Introducción. Los estudiantes universitarios se caracterizan por poseer unos determinados estilos de vida y hábitos de salud en relación a la alimentación, la actividad física y la higiene del sueño que están su vez, relacionados con el consumo del tabaco. Aunque las medidas tomadas por el gobierno para reducir el consumo de tabaco en España han sido efectivas, existe una gran prevalencia de fumadores universitarios. Los estudiantes fumadores se caracterizan por llevar una inadecuada alimentación, realizar poco ejercicio físico y padecer insomnio, factores que derivan en una mayor probabilidad de desarrollar diversas enfermedades y que, como se ha indicado, se relacionan con el hábito de consumir tabaco. Objetivos. En el presente estudio se pretende determinar la prevalencia del consumo, grado de dependencia y estilo de vida de los estudiantes del Campus Universitario Duques de Soria. Metodología. Se realizó una revisión bibliográfica en bases de datos: Scielo, Dialnet, Uvadoc, Scopus, Medline, Redalyc para la posterior elaboración de un cuestionario, que, basado en cuestionarios validados, se entregaría a los estudiantes fumadores del Campus Universitario Duques de Soria para cumplimentarlo de forma voluntaria. Resultados. La prevalencia obtenida de estudiantes fumadores es de 5,95%, siendo el 85,1% fumadores habituales. Respecto el estilo de vida de los estudiantes, su alimentación se caracteriza por llevar una dieta pobre en frutas y verduras y rica en grasas e hidratos de carbono. Así mismo, su higiene del sueño es inadecuada, ya que no suelen tener horario fijo para acostarse y no se sienten descansados al levantarse. Por último, un 86,17% realiza algún deporte, pero no llegan a las recomendaciones mínimas sobre actividad física propuestas por la Organización Mundial de la Salud. Conclusiones. En el Campus Universitario Duques de Soria, existe una baja prevalencia de fumadores y el hábito tabáquico predomina en la población femenina. El estilo de vida se caracteriza por una alimentación pobre en verduras y frutas; un inadecuado patron del sueño y practicar algún deporte aunque no realizar las recomendaciones mínimas de la Organización Mundial de la Salud.Grado en Enfermerí

    Stratigraphic interpretation of the Tohogne borehole (province de Luxembourg). Devonian - Carbinoferous transition

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    The Tohogne borehole section, from the Lower Tournaisian into the Upper Famennian, has a remarkable micropalaeontological content (conodonts, foraminifers, spores) which enabled a detailed subdivision of these strata. New data in biostratigraphy and systematic palaeontology and palaeogeographic implications are presented, as well as correlations with reference sections

    Influence of the North Atlantic on simulated atmospheric variability

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    An atmospheric general circulation model is used to investigate the influence of the North Atlantic Ocean on atmospheric variability. The study covers the period from 1950 to 1994. The observed sea surface temperature and sea ice extension are used to force the atmospheric model. Several configurations of the oceanic boundary conditions were made to isolate the role of the North Atlantic and to study its non-linear interaction with forcings from other oceanic basins. The multi-realization character of the experiments distinguishes between the internal random part and the external forced part of the total variability. The potential predictability can thus be evaluated. The response of the atmosphere is also studied with a modal approach in terms of hemispheric teleconnection patterns. The North Atlantic Ocean has a direct influence on both the Northern Hemisphere annular mode and the Pacific-North-America pattern, leading to a weak predictability. However the direct response is largely modulated by forcings from other oceanic basins. The non-linearity of the system compensates the predictable component of the annular mode induced by the North Atlantic forcing. Furthermore it reduces the forced component of the Pacific-North-America pattern, increasing its chaoticity

    A novel method to assess human population exposure induced by a wireless cellular network

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    <p>This paper presents a new metric to evaluate electromagnetic exposure induced by wireless cellular networks. This metric takes into account the exposure induced by base station antennas as well as exposure induced by wireless devices to evaluate average global exposure of the population in a specific geographical area. The paper first explains the concept and gives the formulation of the Exposure Index (EI). Then, the EI computation is illustrated through simple phone call scenarios (indoor office, in train) and a complete macro urban data long-term evolution scenario showing how, based on simulations, radio-planning predictions, realistic population statistics, user traffic data, and specific absorption rate calculations can be combined to assess the index.</p

    Foramiminifères, spores et coraux du Famennien superieur et du Dinantien du Massif de l'Omolon (extreme-orient sovietique)

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    Faunal assemblages allowing biostratigraphical Upper Famennian and Dinantian correlations between the Omolon Massif and Western Europe were recorded by Simakov in 1979. New investigations in 1981 allowed to improve the correlations using forams, corals and also palynological material from one shaly sample

    On the Thermo-Hydro-Mechanical Behaviour of a Sheared Callovo-Oxfordian Claystone Sample with Respect to the EDZ Behaviour

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    International audienceTo better understand the impact of temperature elevation on the response of the excavation damaged zone around repository cells and galleries for radioactive waste disposal, the combined effects of shear and temperature elevation were investigated in the laboratory on the Cal-lovo-Oxfordian claystone. To do so, a hollow cylinder thermal triaxial cell with short drainage path specifically developed for low permeability rocks was used. Once properly saturated under stress conditions close to in situ, the specimen was sheared along a constant effective mean stress path mimicking the stress path followed during gallery excavation. The shear stress was afterwards released and an undrained heating test was performed on the sheared specimen. It was observed that the temperature increase under undrained conditions led to a thermal increase in pore water pressure resulting in a decrease in mean effective stress that brought back the sheared specimen to failure, evidencing a thermally induced failure. Steady state radial permeability tests performed at various stages of the test demonstrated that the overall permeability of the sheared specimen was comparable to that before shearing, confirming the excellent self-sealing properties of the Callovo-Oxfordian claystone. This shows that, in spite of being possibly remobilised by temperature elevation, the EDZ will keep an overall permeability constant equal to that of the massive rock, keeping the same isolation properties
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