278 research outputs found

    A Mechanistic Modeling Framework for Predicting Metabolic Interactions in Complex Mixtures

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    Background: Computational modeling of the absorption, distribution, metabolism, and excretion of chemicals is now theoretically able to describe metabolic interactions in realistic mixtures of tens to hundreds of substances. That framework awaits validation

    Philosophie sociale

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    Vincent Descombes, JĂ©rĂŽme Dokic, FrĂ©dĂ©ric Nef, directeurs d’études avec Alban Bouvier, professeur Ă  l’UniversitĂ© Aix-Marseille-I Compte rendu non communiquĂ©

    L’émergence en question

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    JĂ©rĂŽme Dokic, Frederic Nef, Bernard Walliser, directeurs d’étudesAlban Bouvier, professeur Ă  l’UniversitĂ© Aix-Marseille-II/Provence L’émergence en question : les niveaux d’explication Ce sĂ©minaire transversal a traitĂ© du problĂšme de l’émergence entendue comme apparition de propriĂ©tĂ©s macroscopiques Ă  partir d’élĂ©ments microscopiques en interaction. Des sĂ©ances spĂ©cialisĂ©es ont donnĂ© la parole Ă  des spĂ©cialistes de disciplines diverses qui ont exposĂ© comment l’émergence Ă©tait traitĂ©e dans leur..

    Philosophie sociale

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    Vincent Descombes, JĂ©rĂŽme Dokic, FrĂ©dĂ©ric Nef, directeurs d’études avec Alban Bouvier, professeur Ă  l’UniversitĂ© Aix-Marseille-I Compte rendu non communiquĂ©

    Assessment of myocardium at risk with contrast enhanced steady-state free precession cine cardiovascular magnetic resonance compared to single-photon emission computed tomography

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    <p>Abstract</p> <p>Background</p> <p>Final infarct size following coronary occlusion is determined by the duration of ischemia, the size of myocardium at risk (MaR) and reperfusion injury. The reference method for determining MaR, single-photon emission computed tomography (SPECT) before reperfusion, is impractical in an acute setting. The aim of the present study was to evaluate whether MaR can be determined from the contrast enhanced myocardium using steady-state free precession (SSFP) cine cardiovascular magnetic resonance (CMR) performed one week after the acute event in ST-elevation myocardial infarction (STEMI) patients with total coronary occlusion.</p> <p>Results</p> <p>Sixteen patients with STEMI (age 64 ± 8 years) received intravenous 99 m-Tc immediately before primary percutaneous coronary intervention. SPECT was performed within four hours. MaR was defined as the non-perfused myocardial volume derived with SPECT. CMR was performed 7.8 ± 1.2 days after the myocardial infarction using a protocol in which the contrast agent was administered before acquisition of short-axis SSFP cines. MaR was evaluated as the contrast enhanced myocardial volume in the cines by two blinded observers. MaR determined from the enhanced region on cine CMR correlated significantly with that derived with SPECT (r<sup>2 </sup>= 0.78, p < 0.001). The difference in MaR determined by CMR and SPECT was 0.5 ± 5.1% (mean ± SD). The interobserver variability of contrast enhanced cine SSFP measurements was 1.6 ± 3.7% (mean ± SD) of the left ventricle wall volume.</p> <p>Conclusions</p> <p>Contrast enhanced SSFP cine CMR performed one week after acute infarction accurately depicts MaR prior to reperfusion in STEMI patients with total occlusion undergoing primary PCI. This suggests that a single CMR examination might be performed for determination of MaR and infarct size.</p

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

    Vapor phase preparation and characterization of the carbon micro-coils

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    Contribution a l'etude de la reactivite de tetraaminophosphoranes tetracycliques et de leurs derives : applications en chimie de coordination

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    CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc
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