Diffusion approximation of a multilocus model with assortative mating

To understand the effect of assortative mating on the genetic evolution of a population, we consider a finite population in which each individual has a type, determined by a sequence of n diallelic loci. We assume that the population evolves according to a Moran model with weak assortative mating, strong recombination and low mutation rates. With an appropriate rescaling of time, we obtain that the evolution of the genotypic frequencies in a large population can be approximated by the evolution of the product of the allelic frequencies at each locus, and the vector of the allelic frequencies is approximately governed by a diffusion. We present some features of the limiting diffusions (in particular their boundary behaviour and conditions under which the allelic frequencies at different loci evolve independently). If mutation rates are strictly positive then the limiting diffusion is reversible and, under some assumptions, the critical points of the stationary density can be characterised.Comment: 56 pages, 8 figures ; corrected typo

Products of Beta matrices and sticky flows

A discrete model of Brownian sticky flows on the unit circle is described: it is constructed with products of Beta matrices on the discrete torus. Sticky flows are defined by their ``moments'' which are consistent systems of transition kernels on the unit circle. Similarly, the moments of the discrete model form a consistent system of transition matrices on the discrete torus. A convergence of Beta matrices to sticky kernels is shown at the level of the moments. As the generators of the n-point processes are defined in terms of Dirichlet forms, the proof is performed at the level of the Dirichlet forms. The evolution of a probability measure by the flow of Beta matrices is described by a measure-valued Markov process. A convergence result of its finite dimensional distributions is deduced

Role of transforming growth factor-β1 in down-regulating TNF production by alveolar macrophages during asbestos-induced pulmonary fibrosis

Activation of alveolar macrophages (AM) for tumour necrosis factor production is suppressed initially during the inflammatory response to fibrogenic dusts. We investigated the mechanisms involved in TNF suppression, notably the role of other AM-derived mediators including prostaglandin E2 (PGE2), transforming growth factor-β1 (TGF-β1), and interleukin 6 (IL-6). The action of PGE2 and TGF-β1, on AM was different. At physiologically relevant doses (25–300 pg/ml), PGE2 did not cause significant inhibition of Hpopolysaccharide (Lps)-induced TNF release by AM in vitro but stimulated IL-6 (up to six fold), an inhibitor of AM-derived TNT. In contrast, TGF-β1 (0.5–50 ng/ml) inhibited both LPS-induced TNT and IL-6 release by 50% but had no effect on PGE2 production by AM. To determine the respective contribution of these different inhibitors in TNF suppression, AM from rats exposed to fibrogenic asbestos for weeks were treated with neutralizing antibody against TGF-β1 or indomethacin, an inhibitor of PGE2 synthesis. Treatment of rat AM with anti-TGF-β1 but not indomethacin, abrogated the observed TNT suppression. These results suggest that an autocrine, TGF-β1-dependent mechanism is involved in the down-regulation of TNF production by rat AM from animals with lung fibrosis

The horse industry in France: some indicators and key figures

The production and uses of horses in France evolved with the course of history and the development of agriculture. However, horses have recently gained a new status, as the centre of a complex and evolving industry. With close to 100,000 broodmares, horse breeding shows a wide variety of breeds distributed over many regions of France. The industry is compartmentalised into different sectors based on the use of horses: racing, equestrian sports, leisure and draught. Horse racing provides a basis for an enormous gambling industry which generates over 6.4 billion euros in turnover. With a new equine policy under way, helped by harmonised measures and modernised partnerships, France has become one of the leading equestrian nations of the world.La production et les usages du cheval en France sont ancrés à la fois dans l'histoire et dans l'agriculture. Le cheval a toutefois acquis un nouveau statut et est devenu le support d'une filière économique complexe, mais en plein développement. Avec près de 100000 juments, l'élevage du cheval est largement diversifié tant par les races que géographiquement. Les circuits de valorisation et de commercialisation sont variables en fonction des différentes utilisations : courses, sports et loisirs équestres, trait. Les courses sont le support de paris générant un chiffre d'affaires de plus de 6,4 milliards d'euros. Une nouvelle politique du cheval est engagée avec des mesures plus harmonisées et favorables et dans un cadre partenarial rénové, permettant à la France d'être une des premières nations hippiques du monde