Prediction Of Beef Fatty Acid Composition Using Near Infrared Spectroscopy: Effects Of Tissue And Sample Preparations

International audienceThe aims of the study were to determine the best site of bovine carcass for predicting fatty acid (FA) composition using a NIRS (near infrared spectroscopy) portable equipment and to study the effect of different methods of sample preparation. 78 animals were sampled from different types and rearing systems. Seven tissues (Longissimus thoracis, Infraspinatus, Diaphragma, Rectus abdominis, shoulder subcutaneous adipose tissue (SAT), intercostal SAT and intermuscular fat at the 5th rib) were measured after sampling and grinding in liquid nitrogen. The effect of samples preparation were measured on carcass (C0), muscle without grinding (B0), ground with a meat chopper (B1), ground with a knife mill (B2) on RA muscle. FA composition was assessed using gas chromatograph and the spectra were measured at wavelengths between 350 and 2500 nm. For adipose tissue, FA were not correctly predicted from NIRS. However, predictions were more satisfactory for the major FA (C16:0, C18:0, C18:1d9c), total saturated and monounsaturated FA of muscles. The results show a better prediction of FA composition concomitant with an increased gradient of sample homogenization. For other FA and especially polyunsaturated fatty acids, the performances were not satisfactory for quantitative purposes whatever the grinding method

Quelques problèmes d'homogénéisation à faible et fort contraste

Dans cette thèse, on étudie l'homogénéisation de problèmes de conduction et d'élasticité linéarisée en dimension~2 et~3. En dimension~2, on traite d'une part de l'homogénéisation de l'effet Hall considéré comme un problème à faible contraste. On établit d'autre part des résultats de compacité et de dualité pour des suites de conductivités non nécessairement symétriques et non uniformément bornées soit inférieurement, soit supérieurement; ce qui correspond à des problèmes à fort contraste. En dimension~3, on s'intéresse à des structures fibrées non périodiques. D'une part, en s'appuyant sur l'homogénéisation à faible contraste de Tartar, on obtient des modèles homogénéisés en conduction et en élasticité isotrope. De plus, on étend le résultat de Tartar à l'élasticité anisotrope, ce qui permet d'obtenir un modèle simple. D'autre part, en homogénéisation à fort contraste, on obtient un modèle correspondant aux cas où le milieu extérieur est faiblement conducteur.This thesis is devoted to the homogenization of conduction and linearized elasticity equations in dimensions~2 and~3. In dimension~2, we first consider the homogenization of the Hall effect which can be seen as a low contrast problem. Then we study the inverse case of high contrast problems. We establish compacity and duality results for sequences of conductivities which are not necessarily symmetric and not uniformly bounded from below or from above. In dimension~3, we are interested in non periodic fibered microstructures. On the one hand, using the small amplitude homogenization procedure of Tartar, we obtain some homogenized models in conduction and in isotropic elasticity. Moreover, we extend the results of Tartar to the anisotropic elasticity, which permits to derive a simplified model. On the other hand, in high contrast homogenization, we obtain a model in the case where the external medium has a low conductivity.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Duality results in the homogenization of two-dimensional high-contrast conductivities

International audienceThe paper deals with some extensions of the Keller-Dykhne duality relations arising in the classical homogenization of two-dimensional uniformly bounded conductivities, to the case of high-contrast conductivities. Only assuming a L-1-bound on the conductivity we prove that the conductivity and its dual converge respectively, in a suitable sense, to the homogenized conductivity and its dual. In the periodic case a similar duality result is obtained under a less restrictive assumption

Modulation de l'expression des transporteurs membranaires au niveau des lymphocytes et du placenta chez l'homme

L efficacité des médicaments agissant sur les lymphocytes humains, ainsi que le degré de passage transplacentaire de nombreux médicaments, peuvent être modulés par le niveau d expression des transporteurs ABC. Parmi les facteurs de variabilité influençant leur expression, nous nous sommes intéressés à l effet inducteur potentiel de plusieurs co-traitements impliquant l activation de différents récepteurs nucléaires. Nous avons montré que la rifampicine et le phénobarbital n induisaient pas la P-gp lymphocytaire in vitro et ex vivo. Nous avons aussi montré sur des lymphocytes en culture que la dexaméthasone induisait la P-gp, d un facteur 8 environ, et très modérément la MRP2 et la MRP5. Nous avons également étudié l influence des glucocorticoïdes sur des cytotrophoblastes humains ex vivo et montré que la dexaméthasone et la betaméthasone induisaient l expression de la P-gp environ d un facteur 4, contrairement à la prednisone sans effet. La quantification des récepteurs nucléaires par qRT-PCR explique partiellement certaines différences d induction. En effet, il s avère que PXR et CAR sont très faiblement exprimés dans les lymphocytes, contrairement à GR, fortement exprimé dans les lymphocytes et les cytotrophoblastes. Notre travail a montré que les risques d interactions médicamenteuses de type induction au niveau lymphocytaire, liés à la P-gp et médiés par les récepteurs nucléaires PXR et CAR, sont sans doute limités (rifampicine, phénobarbital) et qu ils semblent plus importants pour les molécules dont la voie d induction implique GR (glucocorticoïdes). Des résultats similaires ont été obtenus au niveau placentaireThe efficacy of drugs acting within human lymphocytes, as well as the rate of transplacental transfer of numerous drugs, may be modulated by the expression level of ABC transporters. Among the variability factors influencing their expression levels, we were interested in testing whether several co-treatments, involving different nuclear receptors, could be inducers of these transporters. We showed that rifampicin and phenobarbital did not induce P-gp in lymphocytes, neither in an vitro model (CCRF-CEM cells), nor ex vivo (PBMC). Moreover, there was no data regarding nor dexamethasone neither other ABC transporters. We showed that dexamethasone could induce P-gp expression by around 8-fold, and to a lesser extent MRP2 and MRP5 expression in CCRF-CEM cells. We also studied the influence of glucocorticoides on human cytotrophoblasts ex vivo et showed that dexamethasone and betamethasone induced significantly P-gp expression (by around 4-fold). Conversely, prednisone had no effect. The quantification of nuclear receptors expression by qRT-PCR may participate to explain globally these results. Indeed, we showed that PXR and CAR had a very weak expression in lymphocytes, compared to the high expression level of GR in lymphocytes and cytotrophoblasts. As a conclusion, the present work brought to light that the risks of drug interactions caused by inducers at the lymphocyte level and mediated by PXR are CAR are likely to be limited (rifampicin, phenobarbital) and that they may be higher for drugs whose induction pathway is mediated by GR (glucocorticoides). Similar results were obtained in cytotrophoblasts, which are the main cells constituting the human placental barrier.PARIS-BIUP (751062107) / SudocSudocFranceF

Data from: A unifying comparative phylogenetic framework including traits coevolving across interacting lineages

Models of phenotypic evolution fit to phylogenetic comparative data are widely used to make inferences regarding the tempo and mode of trait evolution. A wide range of models is already available for this type of analysis, and the field is still under active development. One of the most needed development concerns models that better account for the effect of within- and between-clade interspecific interactions on trait evolution, which can result from processes as diverse as competition, predation, parasitism, or mutualism. Here, we begin by developing a very general comparative phylogenetic framework for (multi)-trait evolution that can be applied to both ultrametric and nonultrametric trees. This framework not only encapsulates many previous models of continuous univariate and multivariate phenotypic evolution, but also paves the way for the consideration of a much broader series of models in which lineages coevolve, meaning that trait changes in one lineage are influenced by the value of traits in other, interacting lineages. Next, we provide a standard way for deriving the probabilistic distribution of traits at tip branches under our framework. We show that a multivariate normal distribution remains the expected distribution for a broad class of models accounting for interspecific interactions. Our derivations allow us to fit various models efficiently, and in particular greatly reduce the computation time needed to fit the recently proposed phenotype matching model. Finally, we illustrate the utility of our framework by developing a toy model for mutualistic coevolution. Our framework should foster a new era in the study of coevolution from comparative data

Homogenization of the two-dimensional Hall effect

International audienceIn this paper, we study the two-dimensional Hall effect in a highly heterogeneous conducting material in the low magnetic field limit. Extending Bergman's approach in the framework of H-convergence we obtain the effective Hall coefficient which only depends on the corrector of the material resistivity in the absence of a magnetic field. A positivity property satisfied by the effective Hall coefficient is then deduced from the homogenization process. An explicit formula for the effective Hall coefficient is derived for anisotropic interchangeable two-phase composites

OnlineAppendixV2

We provide here the full, uncut, Online Appendix to our paper entitled "A unifying comparative phylogenetic framework including traits coevolving across interacting lineages". The first section is exposed in the attached appendix of the paper, but we let it here for the sake of self-containment. Note that simple equation numbering (e.g. equation (5)) refers to equations printed in the main text, whereas equations exposed in this appendix are designated as, e.g. equation (S5)

The probability distribution of the reconstructed phylogenetic tree with occurrence data

ISSN:0022-5193ISSN:1095-854