Direct measurements of anisotropic energy transfers in a rotating turbulence experiment

We investigate experimentally the influence of a background rotation on the energy transfers in decaying grid turbulence. The anisotropic energy flux density, ${\bf F} ({\bf r}) =$, where $\delta {\bf u}$ is the vector velocity increment over separation ${\bf r}$, is determined for the first time using Particle Image Velocimetry. We show that rotation induces an anisotropy of the energy flux $\nabla \cdot {\bf F}$, which leads to an anisotropy growth of the energy distribution $E({\bf r}) = < (\delta {\bf u})^2 >$, in agreement with the K\'arm\'an-Howarth-Monin equation. Surprisingly, our results prove that this anisotropy growth is essentially driven by a nearly radial, but orientation-dependent, energy flux density ${\bf F} ({\bf r})$.Comment: to appear in Physical Review Letters (July 8, 2011 issue

The Value of Bacterial Culture During Clean Orthopedic Surgery a Prospective Study of 1,036 Patients

Abstract Objective: To determine whether bacterial cultures of the wounds of patients undergoing clean orthopedic surgery would help predict infection. Methods: During 1 year, 1,256 cultures were performed for 1,102 patients who underwent clean orthopedic surgery. Results were analyzed to evaluate their ability to predict postoperative infection. Results: The sensitivity, specificity, positive predictive value, and negative predictive value of the cultures were 38%, 92%, 7%, and 99%, respectively. Conclusions: Cultures performed during clean orthopedic surgery were not useful for predicting postoperative infectio

Langevin PDF simulation of particle deposition in a turbulent pipe flow

The paper deals with the description of particle deposition on walls from a turbulent flow over a large range of particle diameter, using a Langevin PDF model. The first aim of the work is to test how the present Langevin model is able to describe this phenomenon and to outline the physical as- pects which play a major role in particle deposition. The general features and characteristics of the present stochastic model are first recalled. Then, results obtained with the standard form of the model are presented along with an analysis which has been carried out to check the sensitivity of the predictions on different mean fluid quantities. These results show that the physical repre- sentation of the near-wall physics has to be improved and that, in particular, one possible route is to introduce specific features related to the near-wall coherent structures. In the following, we propose a simple phenomenological model that introduces some of the effects due to the presence of turbulent coherent structures on particles in a thin layer close to the wall. The results obtained with this phenomenological model are in good agreement with experimental evidence and this suggests to pursue in that direction, towards the development of more general and rigorous stochastic models that provide a link between a geometrical description of turbulent flow and a statistical one.Comment: 40 pages, 8 figure

La relation entre l’enfant et l’entrée dans la lecture: Etude de cas de sept élèves de 3ème HarmoS

La présente recherche a pour but d’établir un bilan des comportements d’élèves de 3ème HarmoS avec la lecture. Pour ce faire, il est nécessaire d’avoir un regard global sur les apprentissages de la lecture dès son commencement, c’est-à-dire dès sa naissance au sein de la famille jusqu’à ce que l’enfant entre en 3ème année HarmoS, étape charnière dans l’apprentissage de la lecture au travers du moyen d’enseignement « Que d’histoires ! ». Lors de ses expériences, dont le but pour l’enseignant est d’amener l’enfant à ressentir l’envie d’apprendre à lire, il découvre divers supports de lecture dont les fonctions sont multiples. Lors de mon analyse, j’ai cherché à comprendre le comportement que l’enfant entretient avec la lecture lors de son apprentissage en 3ème année HarmoS. Utilise-t-il la lecture comme un outil dans son quotidien ? Y a-t-il un lien entre son niveau de lecture et la transposition de cet outil? Finalement, quelle est sa conception du mot « lire »? Les données se basant sur sept élèves de 3ème HarmoS relevées sous forme qualitative, ainsi j’ai établi des liens entre les éléments théoriques présents et les dires de ces enfants, afin d’avoir une vision plus claire de ce qu’est la lecture pour un enfant au début de son apprentissage du code alphabétique

Selection for reduced muscle glycolytic potential in Large White pigs I. Direct responses

International audienc

Maturation of B Cells in the Lamina Propria of Human Gut and Bronchi in the First Months of Human Life

Little is known of the maturation of the mucosae-associated lymphoid tissue (MALT) in man, because, for ethical reasons, tissues from newborns are not easy to obtain. We used the opportunity provided by autopsies systematically performed in infants who died of Sudden Infant Death Syndrome (SIDS) to study the maturation of the MALT after birth. Gut and bronchus samples of 90 infants from postpartum to 90 months and who died from SIDS were collected and studied by histological and immunofluorescence examination. Plasma cells, absent at birth, appeared within a few hours after birth and initially were of the IgM isotype. IgA plasma cells appeared at 12 days. These cells were first observed in gut and later in bronchi, indicating that maturation of the gut precedes that of bronchi. The number of plasma cells increased rapidly over time and IgA plasma cells became predominant after 3 weeks in the gut and 6 weeks in bronchi. At birth, only small IgM bearing B-cell foci were seen and organized germinal centers appeared to develop over a few days, first in the gut and only later in bronchi. These results confirm that, in man, the MALT organization at birth is still in its fetal form and that maturation depends on intestinal challenges and evolves over several weeks before IgA becomes the predominant isotype secreted

Comparison between the three porcine RN genotypes for growth, carcass composition and meat quality traits

A three-step experimental design has been carried out to add evidence about the existence of the RN gene, with two segregating alleles RN- and rn+, having major effects on meat quality in pigs, to estimate its effects on production traits and to map the RN locus. In the present article, the experimental population and sampling procedures are described and discussed, and effects of the three RN genotypes on growth and carcass traits are presented. The RN genotype had no major effect on growth performance and killing out percentage. Variables pertaining to carcass tissue composition showed that the RN- allele is associated with leaner carcasses (about 1 s.d. effect without dominance for back fat thickness, 0.5 s.d. effect with dominance for weights of joints). Muscle glycolytic potential (GP) was considerably higher in RN- carriers, with a maximum of a 6.85 s.d. effect for the live longissimus muscle GP. Physico-chemical characteristics of meat were also influenced by the RN genotype in a dominant way, ultimate pH differing by about 2 s.d. between homozygous genotypes and meat colour by about 1 s.d. Technological quality was also affected, with a 1 s.d. decrease in technological yield for RN- carriers. The RN genotype had a more limited effect on eating quality. On the whole, the identity between the acid meat condition and the RN- allele effect is clearly demonstrated (higher muscle GP, lower ultimate pH, paler meat and lower protein content), and the unfavourable relationship between GP and carcass lean to fat ratio is confirmed

Selection for reduced muscle glycolytic potential in Large White pigs. II. Correlated responses in meat quality and muscle compositional traits

International audienc