1,071 research outputs found
DRELIO : Un drone hélicoptÚre pour le suivi des zones littorales
International audienceLa connaissance du littoral, sa protection, son amĂ©nagement nĂ©cessitent un suivi des changements qui s'y produisent. Toutefois, en France, devant l'Ă©tendue des façades maritimes Ă couvrir, les techniques de mesures in situ ne peuvent ĂȘtre appliquĂ©es de façon systĂ©matique. Dans ce cas, les techniques de tĂ©lĂ©dĂ©tection spatiale ou aĂ©rienne sont des approches complĂ©mentaires. A partir de ces plates-formes, des images stĂ©rĂ©oscopiques multi-temporelles sont, aprĂšs une sĂ©rie de traitements photogrammĂ©triques appropriĂ©s, directement exploitables sous formes d'orthophotographies et de ModĂšles NumĂ©riques de Terrain (MNT). Ce type de produits permet notamment la quantification des changements morphosĂ©dimentaires Ă l'interface Terre-Mer (transport transversal et longitudinal de sĂ©diments, Ă©rosion,...). Actuellement, la rĂ©solution spatiale des MNT gĂ©nĂ©rĂ©s Ă partir d'images aĂ©riennes ou satellitaires (<50 cm) est insuffisante pour la plupart des applications sur la frange littorale. En outre, dans le cas d'interventions consĂ©cutives Ă un Ă©vĂ©nement extrĂȘme (tempĂȘte, raz de marĂ©e, pollution...), ces systĂšmes manquent de souplesse (trajectoires prĂ©dĂ©finies, contraintes d'altitude, de vitesse, coĂ»t de mise en oeuvre...) L'utilisation de drones constitue donc une alternative intĂ©ressante pour des suivis de prĂ©cision ou des interventions rapides
Experimental study of a preshower module and its readout system - Testbeam and testbench results
Study of multianode photomultipliers for the electomagnetic calorimeter preshower read out of the LHCb experiment
Faulting and volcanism in the axial valley of the slow-spreading center of the Mariana back arc basin from Wadatsumi side-scan sonar images
Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of
American Geophysical Union for personal use, not for redistribution. The definitive version was published
in Geochemistry Geophysics Geosystems 6 (2005): Q05006, doi:10.1029/2004GC000881.We analyzed in detail the geology of the median valley floor of the Mariana Basin slow-spreading ridge using sea surface geophysical data and a high-resolution deep-tow side-scan sonar survey over one spreading segment. Analysis of surface magnetic data indicates highly asymmetric accretion, with the half-spreading rate on the western side of the basin being two to three times larger than on the eastern side. Surface magnetic and reflectivity data together suggest that asymmetric spreading is accomplished through eastward ridge jumps of âŒ10 km of amplitude. Deep-tow backscatter data indicate along-axis variations of the volcanic processes with the emplacement of smooth and hummocky flows at the segment center and end, respectively. This variation likely relates to changes in the effusion rate due to the deepening or even disappearance of the magma chamber toward the segment end. Concerning tectonic processes, we find a power law distribution of the fractures, with an exponent of 1.74. This suggests that within the inner valley floor, fracture growth prevails over fracture nucleation and coalescence and that fractures accommodate less than 8% of the strain. According to our calculation based on a ratio of 0.02 to 0.03 between the vertical displacement and the length of faults, the amount of tectonic strain accommodated in the inner valley floor would consistently be âŒ1.1â3.4%. Data also show two distinct sets of fractures. One trend is parallel to the rift direction at the segment center (âŒN160°E) and perpendicular to the plate separation direction. Another set trends âŒ17° oblique to this direction (âŒN175°E) and is located over the eastern part of the valley, in the vicinity of a major bounding fault also trending âŒN175°E, that is, obliquely to the direction of plate motion. We modeled the stress field near a major fault that is oblique to the regional stress field associated with plate separation using a three-dimensional boundary element approach. We found that the orientation of the predicted fissuring near the oblique fault is locally rotated by âŒ15° due to a flexure of the bending plate close to this fault.The KR03-12 cruise was funded by both JAMSTEC and ORI. This research was supported by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the United States Geological Survey
Morphology and dynamics of inflated subaqueous basaltic lava flows
International audienceDuring eruptions onto low slopes, basaltic Pahoehoe lava can form thin lobes that progressively coalesce and inflate to many times their original thickness, due to a steady injection of magma beneath brittle and viscoelastic layers of cooled lava that develop sufficient strength to retain the flow. Inflated lava flows forming tumuli and pressure ridges have been reported in different kinds of environments, such as at contemporary subaerial Hawaiian-type volcanoes in Hawaii, La RĂ©union and Iceland, in continental environments (states of Oregon, Idaho, Washington), and in the deep sea at Juan de Fuca Ridge, the Galapagos spreading center, and at the East Pacific Rise (this study). These lava have all undergone inflation processes, yet they display highly contrasting morphologies that correlate with their depositional environment, the most striking difference being the presence of water. Lava that have inflated in subaerial environments display inflation structures with morphologies that significantly differ from subaqueous lava emplaced in the deep sea, lakes, and rivers. Their height is 2-3 times smaller and their length being 10-15 times shorter. Based on heat diffusion equation, we demonstrate that more efficient cooling of a lava flow in water leads to the rapid development of thicker (by 25%) cooled layer at the flow surface, which has greater yield strength to counteract its internal hydrostatic pressure than in subaerial environments, thus limiting lava breakouts to form new lobes, hence promoting inflation. Buoyancy also increases the ability of a lava to inflate by 60%. Together, these differences can account for the observed variations in the thickness and extent of subaerial and subaqueous inflated lava flows
Circulating adrenomedullin estimates survival and reversibility of organ failure in sepsis: the prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock-1 (AdrenOSS-1) study
Background: Adrenomedullin (ADM) regulates vascular tone and endothelial permeability during sepsis. Levels of circulating biologically active ADM (bio-ADM) show an inverse relationship with blood pressure and a direct relationship with vasopressor requirement. In the present prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock 1 (, AdrenOSS-1) study, we assessed relationships between circulating bio-ADM during the initial intensive care unit (ICU) stay and short-term outcome in order to eventually design a biomarker-guided randomized controlled trial. Methods: AdrenOSS-1 was a prospective observational multinational study. The primary outcome was 28-day mortality. Secondary outcomes included organ failure as defined by Sequential Organ Failure Assessment (SOFA) score, organ support with focus on vasopressor/inotropic use, and need for renal replacement therapy. AdrenOSS-1 included 583 patients admitted to the ICU with sepsis or septic shock. Results: Circulating bio-ADM levels were measured upon admission and at day 2. Median bio-ADM concentration upon admission was 80.5 pg/ml [IQR 41.5-148.1 pg/ml]. Initial SOFA score was 7 [IQR 5-10], and 28-day mortality was 22%. We found marked associations between bio-ADM upon admission and 28-day mortality (unadjusted standardized HR 2.3 [CI 1.9-2.9]; adjusted HR 1.6 [CI 1.1-2.5]) and between bio-ADM levels and SOFA score (p < 0.0001). Need of vasopressor/inotrope, renal replacement therapy, and positive fluid balance were more prevalent in patients with a bio-ADM > 70 pg/ml upon admission than in those with bio-ADM †70 pg/ml. In patients with bio-ADM > 70 pg/ml upon admission, decrease in bio-ADM below 70 pg/ml at day 2 was associated with recovery of organ function at day 7 and better 28-day outcome (9.5% mortality). By contrast, persistently elevated bio-ADM at day 2 was associated with prolonged organ dysfunction and high 28-day mortality (38.1% mortality, HR 4.9, 95% CI 2.5-9.8). Conclusions: AdrenOSS-1 shows that early levels and rapid changes in bio-ADM estimate short-term outcome in sepsis and septic shock. These data are the backbone of the design of the biomarker-guided AdrenOSS-2 trial. Trial registration: ClinicalTrials.gov, NCT02393781. Registered on March 19, 2015
First results of the CRLN seismic network in the western Corinth Rift: evidence for old-fault reactivation
Determination of gamma and -2beta_s from charmless two-body decays of beauty mesons
See paper for full list of authorsInternational audienceUsing the latest LHCb measurements of time-dependent CP violation in the B^0_s -> K^+K^- decay, a U-spin relation between the decay amplitudes of B^0_s -> K^+K^- and B^0 -> \pi^+\pi^- decay processes allows constraints to be placed on the angle gamma of the unitarity triangle and on the B^0_s mixing phase -2\beta_s. Results from an extended approach, which uses additional inputs on B^0 -> \pi^0\pi^0 and B^+ -> \pi^+\pi^0 decays from other experiments and exploits isospin symmetry, are also presented. The dependence of the results on the maximum allowed amount of U-spin breaking is studied. At 68% probability, the value \gamma = ( 63.5 +7.2 -6.7 ) degrees modulo 180 degrees is determined. In an alternative analysis, the value -2\beta_s = -0.12 +0.14 -0.16 rad is found. In both measurements, the uncertainties due to U-spin breaking effects up to 50% are included
Contribution française à l'upgrade de LHCb
La contribution française à l'upgrade de LHCb est d etaillée dans ce document et s'inscrit dans le prolongement du Framework TDR soumis au LHCC le 25 mai 2012. La France a contribué à la conception et à la réalisation de la mécanique et de l'électronique de lecture des calorimÚtres. Elle est l'acteur principal du systÚme de déclenchement de premier niveau et l'initiatrice du projet DIRAC, progiciel de traitement et d'analyse de données dans un environnement distribué. Les physiciens et ingénieurs français ont de nombreuses responsabilités de premier plan et sont trÚs fortement impliqués dans l'analyse des données. Les groupes français souhaitent poursuivre leur forte participation a l'expérience en contribuant a son upgrade, notamment l'électronique de lecture des calorimÚtres et du trajectographe en fibres scintillantes ainsi qu'au data processing
Contribution française à l'upgrade de LHCb
La contribution française à l'upgrade de LHCb est d etaillée dans ce document et s'inscrit dans le prolongement du Framework TDR soumis au LHCC le 25 mai 2012. La France a contribué à la conception et à la réalisation de la mécanique et de l'électronique de lecture des calorimÚtres. Elle est l'acteur principal du systÚme de déclenchement de premier niveau et l'initiatrice du projet DIRAC, progiciel de traitement et d'analyse de données dans un environnement distribué. Les physiciens et ingénieurs français ont de nombreuses responsabilités de premier plan et sont trÚs fortement impliqués dans l'analyse des données. Les groupes français souhaitent poursuivre leur forte participation a l'expérience en contribuant a son upgrade, notamment l'électronique de lecture des calorimÚtres et du trajectographe en fibres scintillantes ainsi qu'au data processing
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