Prevention of chronic renal failure in the adult

peer reviewedChronic renal failure is an unrecognised disease, with an insidious and rather silent development, for which the general practitioners are too often passive. This review would like to insist on the detection of people at risk or with early abnormalities, on the optimal guidelines to slowdown the evolution to more severe and irreversible stages, on the prevention of uremic and cardiovascular complications and on the preparation to end stage renal treatments

New Potential Model for Molecular Dynamic Simulation of liquid HF. II -Parameter Optimization for Repulsion-Dispersion potential

International audienceIn order to build a complete potential model to perform classical molecular dynamic simulations of liquid HF, a new optimization method is proposed to obtain transferable parameters for repulsion-dispersion potential on the basis of ab initio reference data. This process is decomposed into two steps. The first step, using the force-matching method, consists in exploring the parameter space and selecting a first potential used as a start point for the second step. This last step consists in optimizing the parameters of the selected potential in order to reproduce reference thermodynamic and structural data. The obtained potential correctly reproduces the radial distribution functions and the pressures of HF liquid over a large range of thermodynamic states

Molecular Simulations of Hugoniots of detonation products mixtures at chemical equilibrium: Microscopic calculation of the Chapman-Jouguet State

International audienceIn this work, we used simultaneously the Reaction Ensemble Monte Carlo (ReMC) method and the Adaptive Erpenbeck Equation Of State (AE-EOS) method to directly calculate the thermodynamical and chemical equilibrium of mixtures of detonation products on the Hugoniot curve. The ReMC method (W. R. Smith and B. Triska, J. Chem. Phys. 100, pp 3019-3027 (1994)) allows to reach the chemical equilibrium of a reacting mixture, and the AE-EOS method (J. J. Erpenbeck, Phys. Rev. A, 46, p 6406 (1992)) constrains the system to satisfy the Hugoniot relation. Once the Hugoniot curve of the detonation products mixture is established, the CJ state of the explosive can be determined. Performing a NPT simulation at P(CJ) , T(CJ) , we then calculate the direct thermodynamic properties and the following derivative properties of the system using a fluctuation method: calorific capacities, sound velocity and Gruneisen coefficient. As the composition fluctuates, and the number of particles is not necessarily constant in this ensemble, a fluctuation formula has been developed to take into account the fluctuations of mole number and composition. This type of calculation has been applied to several usual energetic materials: nitromethane, tetranitromethane, hexanitroethane, PETN and RDX

Charcoal kilns and environmental history in the eastern Pyrenees (France). A methodological approach

International audienceSince 15 years, an interdisciplinary research program on long-term forest history and the impact of metallurgy has been undertaken in the eastern Pyrenees. The objective is to describe the spatial evolution of forests and pastoral landscapes and the principal historical events and their causes. Our methodology is based on large-scale regressive studies of various characteristic sites (in valleys or forests) and includes the application of history, phytogeography, palynology, anthropology and archaeology. Remains of charcoal kilns are numerous in the mouton forest areas, wether these are actual or potential, all over the eastern Pyrenees and in particular in Ariege and in the Catalan mountains. Charcoal kilns can thus be used as tool for reconstructing environmental history and ancient woodlands. Two different methods are described here : (i) an anthraco-biogeographic method, based on a geosystemic approach, comparative studies and spatialisation of results ; (ii) an archeo-environmental method, that allows a precise diachronic study of limited forest units and charcoal kilns sites.Un programme interdisciplinaire de recherche est conduit depuis 15 ans sur l'histoire des forêts et l'impact de la métallurgie au bois dans les Pyrénées de l'est. L'objectif est de décrire l'évolution spatiale des paysages forestiers et pastoraux et de saisir les principaux seuils historiques et leurs causes. La méthodologie est basée sur l'étude régressive à grande échelle de sites caractéristiques (vallée ou unités forestières), en utilisant la phytogéographie, la palynologie, l'anthracologie et l'archéologie. Dans toutes les Pyrénées de l'est, en particulier dans les montagnes ariégeoises et catalanes, les restes d'anciennes charbonnières sont innombrables dans l'ensemble de l'aire de la forêt, actuelle ou potentielle. Les charbonnières ont donc été utilisées en tant qu'outil pour l'histoire de l'environnement et la reconstitution des forêts du passé. Deux méthodes sont décrites ici : (i) la méthode anthraco-biogéographique qui est basée sur une démarche géosystémique et permet une approche comparative et spatialité ; (ii) la méthode archéo-environnementale qui permet une étude diachronique précise d'unités forestières limitées et des sites de charbonnage

Histoire de l'environnement et cartographie du temps dans la moitié est des Pyrénées. Pour une " chrono-chorologie ".

Des recherches interdisciplinaires ont été menées à partir de la fin des années 1980 dans les Pyrénées. Elles portent sur une période allant du Néolithique à l'actuel. Un des objectifs de ces travaux était d'obtenir une représentation spatiale des états successifs de l'environnement sous forme de modèles paysagers ou de cartographies éco-historiques. Ces représentations spatiales sont issues du croisement de relevés phytogéographiques et de données historiques, archéologiques, paléo-environnementales. Elles ont été facilitées par l'impact ancien de la métallurgie au bois et du charbonnage dans toute la moitié orientale des Pyrénées. En effet, la multitude de vestiges que ces pratiques ont laissé dans tout l'espace étudié (charbonnières, crassiers de forges, mines) permet une spatialisation des modes d'exploitation passés, et une analyse comparative entre sources historiques et paléo-environnementales. Est présentée ici une synthèse chronologique de l'évolution des espaces forestiers à l'échelle des Pyrénées de l'est, sous la forme de chrono-systèmes. Ces chrono-systèmes font ensuite l'objet d'une tentative de cartographie sous forme d'états successifs de l'environnement à l'échelle 1/250 000ème

Bilateral kidney preservation by volumetric-modulated arc therapy (RapidArc) compared to conventional radiation therapy (3D-CRT) in pancreatic and bile duct malignancies

<p>Abstract</p> <p>Background</p> <p>To compare volumetric-modulated arc therapy plans with conventional radiation therapy (3D-CRT) plans in pancreatic and bile duct cancers, especially for bilateral kidney preservation.</p> <p>Methods</p> <p>A dosimetric analysis was performed in 21 patients who had undergone radiotherapy for pancreatic or bile duct carcinoma at our institution. We compared 4-field 3D-CRT and 2 arcs RapidArc (RA) plans. The treatment plan was designed to deliver a dose of 50.4 Gy to the planning target volume (PTV) based on the gross disease in a 1.8 Gy daily fraction, 5 days a week. Planning objectives were 95% of the PTV receiving 95% of the prescribed dose and no more than 2% of the PTV receiving more than 107%. Dose-volume histograms (DVH) for the target volume and the organs at risk (right and left kidneys, bowel tract, liver and healthy tissue) were compared. Monitor units and delivery treatment time were also reported.</p> <p>Results</p> <p>All plans achieved objectives, with 95% of the PTV receiving ≥ 95% of the dose (D95% for 3D-CRT = 48.9 Gy and for RA = 48.6 Gy). RapidArc was shown to be superior to 3D-CRT in terms of organ at risk sparing except for contralateral kidney: for bowel tract, the mean dose was reduced by RA compared to 3D-CRT (16.7 vs 20.8 Gy, p = 0.0001). Similar result was observed for homolateral kidney (mean dose of 4.7 Gy for RA vs 12.6 Gy for 3D-CRT, p < 0.0001), but 3D-CRT significantly reduced controlateral kidney dose with a mean dose of 1.8 Gy vs 3.9 Gy, p < 0.0007. Compared to 3D-CRT, mean MUs for each fraction was significantly increased with RapidArc: 207 vs 589, (p < 0.0001) but the treatment time was not significantly different (2 and 2.66 minutes, p = ns).</p> <p>Conclusion</p> <p>RapidArc allows significant dose reduction, in particular for homolateral kidney and bowel, while maintaining target coverage. This would have a promising impact on reducing toxicities.</p