The Embedded Super Star Cluster of SBS0335-052

We analyze the infrared (6-100 micron) spectral energy distribution of the blue compact dwarf and metal-poor (Z=Z_solar/41) galaxy SBS0335-052. With the help of DUSTY (Ivezic et al. 1999), a program that solves the radiation transfer equations in a spherical environment, we evaluate that the infrared (IR) emission of SBS0335-052 is produced by an embedded super-star cluster (SSC) hidden under 10^5 M_solar of dust, causing 30 mag of visual extinction. This implies that one cannot detect any stellar emission from the 2x10^6 M_solar stellar cluster even at near-infrared (NIR) wavelengths. The derived grain size distribution departs markedly from the widely accepted size distribution inferred for dust in our galaxy (the so-called MRN distribution, Mathis et al. 1977), but resembles what is seen around AGNs, namely an absence of PAH and smaller grains, and grains that grow to larger sizes (around 1 micron). The fact that a significant amount of dust is present in such a low-metallicity galaxy, hiding from UV and optical view most of the star formation activity in the galaxy, and that the dust size distribution cannot be reproduced by a standard galactic law, should be borne in mind when interpreting the spectrum of primeval galaxies.Comment: 32 pages, 3 figures,accepted for publication in A

Analyse stochastique de signaux multi-fractaux et estimations de paramètres

Le mouvement brownien fractionnaire (MBF) défini par Mandelbrot et Van Ness (1968) est utilisé dans de nombreuses situations. Mais, de part sa définition, il ne peut modéliser que des processus de R à valeurs dans R. Pour étudier des radiographies d'os afin de déterminer si une personne est atteinte ou non de l'ostéoporose, nous avions besoin d'un champ défini sur R2 à valeurs dans R. Nous avons donc généralisé le MBF et construit le drap brownien fractionnaire (DBF) dépendant de deux paramètres a et b. Nous avons montré que ce champ, comme le MBF, était auto-simulaire, à accroissements stationnaires. Puis nous avons défini des estimateurs de ces paramètres et construit un test d'auto-similarité en utilisant des techniques d'Istas et Lang (1997) comme le fait Bardet (1999) pour le MBF. Ce test d'auto-similarité nous a permis de montrer que les radiographies d'os ne possédaient pas cette propriété. En collaboration avec A. Ayache, nous avons défini un nouveau champ : le drap brownien multifractionnaire (DBM), non auto-similaire, en substituant aux paramètres a et b des fonctions höldériennes comme l'ont fait Lévy-Vehel, Peltier (1995) ou Bénassi, Jaffard, Roux (1997) pour le MBF. Nous nous sommes intéressés aux propriétés locales de ce champ, puis nous avons construit des estimateurs des fonctions a et b afin d'appliquer ce nouveau modèle à la caractérisation de l'ostéoporose.ORLEANS-BU Sciences (452342104) / SudocSudocFranceF

Dynamique et stabilité d'un système discret en présence de contact et de frottement

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Prédire à partir des pratiques d'élevage le rendement des carcasses et la tendreté de la noix d'entrecôte

National audienc

Prediction of beef carcass and meat traits from rearing factors in young bulls and cull cows

International audienceThe aim of this study was to predict the beef carcass and LM (thoracis part) characteristics and the sensory properties of the LM from rearing factors applied during the fattening period. Individual data from 995 animals (688 young bulls and 307 cull cows) in 15 experiments were used to establish prediction models. The data concerned rearing factors (13 variables), carcass characteristics (5 variables), LM characteristics (2 variables), and LM sensory properties (3 variables). In this study, 8 prediction models were established: dressing percentage and the proportions of fat tissue and muscle in the carcass to characterize the beef carcass; cross-sectional area of fibers (mean fiber area) and isocitrate dehydrogenase activity to characterize the LM; and, finally, overall tenderness, juiciness, and flavor intensity scores to characterize the LM sensory properties. A random effect was considered in each model: the breed for the prediction models for the carcass and LM characteristics and the trained taste panel for the prediction of the meat sensory properties. To evaluate the quality of prediction models, 3 criteria were measured: robustness, accuracy, and precision. The model was robust when the root mean square errors of prediction of calibration and validation sub-data sets were near to one another. Except for the mean fiber area model, the obtained predicted models were robust. The prediction models were considered to have a high accuracy when the mean prediction error (MPE) was ≤0.10 and to have a high precision when the was the closest to 1. The prediction of the characteristics of the carcass from the rearing factors had a high precision ( > 0.70) and a high prediction accuracy (MPE 0.10). Only the flavor intensity of the beef score could be satisfactorily predicted from the rearing factors with high precision ( = 0.72) and accuracy (MPE = 0.10). All the prediction models displayed different effects of the rearing factors according to animal categories (young bulls or cull cows). In consequence, these prediction models display the necessary adaption of rearing factors during the fattening period according to animal categories to optimize the carcass traits according to animal categories

Amélioration de la qualité sensorielle de la viande à l'aide des pratiques d'élevage

National audienceTo identify the benefic effects of breeding practices, for the fattening period, on the Longissimus Thoracis sensory properties, a dataset obtained from 329 young bulls (2 breed types: beef and hardy) was analyzed. Animals were classified in 2 clusters: high and low sensory quality of beef meat. Different breeding practices combinations driven to high sensory quality were highlighted with decision trees, according to breed types. A higher beef quality is possible with a forage intake ≥ 1.95 kg DM/d in the fattening diet and a fattening period duration < 178 d for young beef breed bulls. The slaughter age of young bulls had a positive impact on beef quality of hardy breeds (≥ 17.2 mo) and beef breeds (between 15.4 and 16.8 mo) if it was combined with a longer fattening period duration and a higher average daily gain, for beef breeds and in addition with a heavier weight for hardy breeds

Validation du questionnaire de précarité EPICES dans la population des femmes enceintes

International audienc

Quantitative determination of interfacial copolymers from co-extruded films

International audienc