Modèles probabilistes de la dégradation des matériaux, structures et ouvrages

National audienceDegradation phenomena of materials and structures are a major industrial preoccupation. Indeed, they condition strategies on inspection, maintenance, repair and extending the service life of facilities. We introduce here the Theme 4 of the JFMS 2014 which was devoted to the probabilistic modelling of degradations caused by the mechanical behaviour and the natural environment of materials and structures. This document presents briefly the 6 papers related to the Theme 4 JFMS 2014 and it summarizes the contribution of these papers to the probabilistic modelling of degradations.Les phénomènes de dégradation des matériaux et des structures constituent une préoccupation industrielle majeure. Ils conditionnent les stratégies d’inspection, maintenance, réparation et prolongation de la durée de vie des installations. Nous introduisons ici le Thème 4 des JFMS 2014 qui a été consacré à la modélisation probabiliste des dégradations dues au fonctionnement mécanique et à l’environnement naturel des matériaux et des structures. Ce document présente les 6 communications associées au Thème 4 des JFMS 2014 et synthétise l’apport de ces communications à la modélisation probabiliste des dégradations

Analytical prediction of the polarized Doppler spectrum from nonlinear ocean surface at microwave frequency

International audienceWe present the use of combined hydrodynamic and electromagnetic analytical models for the simulation of the polarized ocean Doppler spectrum at microwave frequencies. We consider linear and weakly nonlinear sea surfaces after the Choppy Wave Model and incorporate them in the Weighted Curvature Approximation surface scattering method. Statistical expressions are derived, for the Doppler spectrum as well as for its central frequency and width. Results compare favorably with rigorous numerical computations for one-dimensional surfaces published in the literature. The simplicity of the analytical models provide a valuable tool for the Doppler analysis of two-dimensional sea-surfaces

Analytical techniques for the Doppler signature of sea surfaces in the microwave regime-II : nonlinear surfaces

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Fabrication of bicontinuous double networks as thermal and pH stimuli responsive drug carriers for on-demand release

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Smart Eyeglasses: A Valid and Reliable Device to Assess Spatiotemporal Parameters during Gait

International audienceThe study aims to determine the validity and reproducibility of step duration and step length parameters measured during walking in healthy participants using an accelerometer embedded in smart eyeglasses. Twenty young volunteers participated in two identical sessions comprising a 30 s gait assessment performed at three different treadmill speeds under two conditions (i.e., with and without a cervical collar). Spatiotemporal parameters (i.e., step duration and step length normalized by the lower limb length) were obtained with both the accelerometer embedded in smart eyeglasses and an optoelectronic system. The relative intra-and inter-session reliability of step duration and step length computed from the vertical acceleration data were excellent for all experimental conditions. An excellent absolute reliability was observed for the eyeglasses for all conditions and concurrent validity between systems was observed. An accelerometer incorporated in smart eyeglasses is accurate to measure step duration and step length during gait

Modelization of microwave doppler spectrum from nonlinear ocean profiles at grazing angles

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Sea surface microwave scattering at extreme grazing angle : numerical investigation of the Doppler shift

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Cholesterol-lowering effect of non-viscous soluble dietary fiber NUTRIOSE (R) 6 in moderately hypercholesterolemic hamsters

International audienceNUTRIOSE (R) 6 is a new wheat starch-based low-digestible carbohydrate. This study investigated the effect of this soluble non-viscous fiber on cholesterol metabolism. Hamsters fed with 0.25% cholesterol-enriched diet (CHO) were given graded amounts of NUTRIOSE (R) 6, i.e. 0% (cellulose, CHO), 3% (N3), 6% (N6) or 9% (N9) (w:w). As compared to CHO diet, 9% NUTRIOSE (R) 6 significantly lowered plasma and LDL cholesterol by 14.5 and 23.8%, respectively. The LDL-cholesterol lowering effect was also significant with the 6% dose (-21.4%). NUTRIOSE (R) 6 diets prevented hepatic cholesterol accumulation (-10 to -20%) and significantly decreased bile cholesterol (-47 to -68%) and phospholipids (-30 to -45%) concentrations. The 9% NUTRIOSE (R) 6 diet significantly decreased the rate of dietary cholesterol absorption (-25%) and markedly stimulated faecal neutral sterol (+81%) and bile salts (+220%) excretion. No significant change in cholesterol 7-alpha-hydroxylase or LDL-receptor activities was observed whereas 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity was reduced by 29%. Reduced cholesterol and bile salt absorptions and lowered cholesterol synthesis are likely mechanisms underlying the cholesterol lowering effect of NUTRIOSE (R) 6. Results suggest the use of NUTRIOSE (R) 6 as a new dietary cholesterol-lowering agent that should be tested in humans as treatment and evenly prevention of mild hypercholesterolemia

High and low pathogenicity avian influenza virus discrimination and prediction based on volatile organic compounds signature by SIFT-MS: a proof-of-concept study

Abstract High and low pathogenicity avian influenza viruses (HPAIV, LPAIV) are the primary causes of poultry diseases worldwide. HPAIV and LPAIV constitute a major threat to the global poultry industry. Therefore, early detection and well-adapted surveillance strategies are of the utmost importance to control the spread of these viruses. Volatile Organic Compounds (VOCs) released from living organisms have been investigated over the last decades as a diagnostic strategy. Mass spectrometry instruments can analyze VOCs emitted upon viral infection. Selected ion flow tube mass spectrometry (SIFT-MS) enables direct analysis of cell headspace in less than 20 min. As a proof-of-concept study, we investigated the ability of a SIFT-MS coupled sparse Partial Least Square-Discriminant Analysis analytical workflow to discriminate IAV-infected cells. Supernatants of HPAIV, LPAIV, and control cells were collected from 1 to 72 h post-infection and analyzed using our analytical workflow. At each collection point, VOCs' signatures were first identified based on four independent experiments and then used to discriminate the infectious status of external samples. Our results indicate that the identified VOCs signatures successfully discriminate, as early as 1-h post-infection, infected cells from the control cells and differentiated the HPAIV from the LPAIV infection. These results suggest a virus-dependent VOCs signature. Overall, the external samples' status was identified with 96.67% sensitivity, 100% specificity, and 97.78% general accuracy