A relationship between non-exponential stress relaxation and delayed elasticity in the viscoelastic process in amorphous solids: Illustration on a chalcogenide glass

International audienceInorganic glasses are viscoelastic materials since they exhibit, below as well as above their glass transition temperature, a viscoelas-tic deformation under stress, which can be decomposed into a sum of an elastic part, an inelastic (or viscous) part and a delayed elastic part. The delayed elastic part is responsible for the non-linear primary creep stage observed during creep tests. During a stress relaxation test, the strain, imposed, is initially fully elastic, but is transformed, as the stress relaxes, into an inelastic and a delayed elastic strains. For linear viscoelastic materials, if the stress relaxation function can be fitted by a stretched exponential function, the evolution of each part of the strain can be predicted using the Boltzmann superposition principle. We develop here the equations of these evolutions, and we illustrate their accuracy by comparing them with experimental evolutions measured on GeSe 9 glass fibers. We illustrate also, by simple equations, the relationship between any kind of relaxation function based on additive contribution of different relaxation processes and the delayed elastic contribution to stress relaxation: the delayed elasticity is directly correlated to the dispersion of relaxations times of the processes involved during relaxation

The Chardonnay wine concept: legend or reality?

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The role of olfactin in the elaboration and use of the Chardonnay wine concept

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Chardonnay wine aroma: a conjoint study between typicality assessment and olfactometric analysis

International audienceChardonnay is one of the widely spread white grape variety in the world and is especially important in Burgundy and Champagne French vineyards. Chardonnay wines present a large sensorial variability but also some common features. The objective of this work was to identify the key odorants that account for the typicality of Chardonnay wines. Two complementary approaches were carried out. The first one was aimed to assess the typicality of the samples, and the second one was an olfactometry approach aimed to identify the key odorants. First, a panel of French wine experts (n=28) assessed the typicality offorty-eight French white wines (29 from the Chardonnay variety and 19 from other white varieties: Aligoté, Chenin, Marsanne, Melon de Bourgogne, Pinot blanc, Sauvignon and Sylvaner) according to their Chardonnay concept. As expected, wines from the Chardonnay varicty were judged as globally more typical than the wines from other varieties, although a large overlap was observed. A subset of eighteen wines was selected for further analysis. The selected wines were either highly or lowly typical and for both typicality levels, some were from Chardonnay grapes and some from other varieties. Secondly, the 18 wines were analysed by Gas Chromatography-Olfactometry (GC-0) according to the detection frequency method (Pollien et al. 1997) by a trained panel (n=l 7). Seventy-two odorant areas (OA) were found. Partial Least Square regression between typicality scores and the detection frequency of each OA showed that 10 of the OA were potentially responsible of a high level of typicality. The identification of the corresponding compounds is currently undertaken

Etude des caractères sensoriels et non sensoriels d’une appellation d’origine contrôlée, une façon de protéger un terroir : Exemple de l’AOC Fleurie

Communication orale avec actes dans un colloque international.International audienceDepuis 1994, l’INAO a mis en place un groupe d’experts pour clarifier et formaliser les liens entre les caractéristiques d’un produit et son origine géographique. Ces réflexions ont abouti aux définitions des notions de terroir, typicité et typicité liée au terroir. En janvier 2007, à partir de ces concepts, la direction de l’INAO a missionné un groupe de travail pour élaborer des outils à destination des professionnels. Cette mission urgente s’est inscrite dans le cadre de la réforme des signes de l’origine et de la qualité. . Pour atteindre cet objectif, le groupe de travail "Terroir, typicité, évaluation sensorielle" de l’INAO , avec l’appui de ses partenaires scientifiques et techniques, a mis en place quatre expérimentations pour proposer une démarche opérationnelle aux professionnels de la filière viticole. Ainsi l’analyse des caractéristiques qui sous-tendent la typicité des appellations d’origine (groupe humain de référence, l’inventaire des savoirs partagés,…) et l’utilisation d’une méthodologie d’évaluation sensorielle relevant d’une approche globale (délimitation de l’espace sensoriel) sont autant de moyens mis à disposition des professionnels. . La présentation de l’expérimentation mise en place avec les professionnels de l’AOC Fleurie permettra de mieux appréhender l’intérêt d’une telle démarche dans le contexte viticole actuel. D’ores et déjà, cette approche permet d’aider les professionnels à donner un sens à leur AOC en lien au terroir et apporte une cohérence dans la gestion, la défense et la communication aux consommateurs

Les omnipraticiens a faible activite liberale : France 1990

SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 10931 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

L' hypertension arterielle en France Prevalence et prise en charge therapeutique

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : RP 16075 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc