Probing the Scattering of Equivalent Electroweak Bosons

We analyze the kinematic conditions under which the scattering of equivalent massive spin-1 vector bosons factorizes out of the complete process. In practice, we derive the conditions for the validity of the effective W approximation, proposed long ago but never established on a firm basis. We also present a parametric estimate of the corrections to the approximation and explicitly check its validity in two examples.Comment: 36 pages, 14 figures, references adde

Nonzero degree tangential maps between dual symmetric spaces

We construct a tangential map from a locally symmetric space of noncompact type to its dual compact type twin. By comparing the induced map in cohomology to a map defined by Matsushima, we conclude that in the equal rank case the map has a nonzero degree.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol1/agt-1-35.abs.htm

Fruit carotenoids affect the bioaccessibility and cellular uptake of ß-carotene from orange fleshed sweet potato

Context and motivation of the work: To fight against vitamin A deficiency in developing countries, consumption of orange fleshed sweet potato (OFSP) which contains high concentrations of beta-carotene (provitamin A) is currently promoted. Indeed, clinical studies show that the vitamin A status was increased in children fed with OFSP (1). However, information on how well provitamin A was absorbed by intestinal cells is unclear and depends of bioaccessibility. Bioaccessibility of carotenoids depends on various factors included food matrix, food preparation method, presence of fiber and dietary fat or other microconstituants in the food (2).This last point and especially the interaction between carotenoids could be well documented. Moreover, few studies reports informations about the interaction through food matrix. The objective of this study is to assess the effect of carotenoids from fruits juices on the bioaccessibility and cellular uptake of BC from OFSP by using the in vitro digestion coupled with Caco-2 cell culture model. Materiel and methods: To simulate gastric and small intestinal phases of digestion, boiled OFSP (5g) mixed with fruit juice samples (30 ml) in saline solution were incubated at 37 °C (pH 4, pepsin, 30 minutes).Then, the pH was adjusted 6 and bile extract and pancreatin were added for 30 minutes. Micelles were collected in aqueous fraction after centrifugation and filtration (0.22?m). A micellarisation test without food matrix was also investigated (equimolar quantity of carotenoids, 5 ml of 100 mg/ml bile, 17h, 37 °C). Digestat from in vitro digestion were incubated (1h30) on Caco-2 TC7cells cultivated 21 days on wells in order to study the intestinal absorption. Extraction and HPLC analysis of carotenoids from micelles and from OFSP food products were carried out according previous study (3). Results: Effect of fruit juice on the micellarization of beta-carotene from OFSP showed that addition of Pink grapefruit reduces BC micellarization whereas kiwi juice and Clementine increased all-trans BC, but decreased 13-cis BC. Lycopene, beta-cryptoxanthine and lutein carotenoids as standard carotenoids were added to OFSP instead of fruit juices during in vitro digestion and confirmed some carotenoid interactions particularly for lycopene. Micellarization test showed that lycopene decreased and BCX increased. Cellular uptake of all- trans BC from digested OFSP (36%) and 13-cis BC (13 %) significantly decreased in presence of fruit juices. Conclusion: This study shows that carotenoids from fruit juice modify the bioaccessibility and cellular uptake of BC from OFSP. However, further investigations are needed to identify other components responsible of interactions in order to show efficacy of OFSP for maintaining adequate vitamin A status in a meal. (Texte intégral

On the Eisenstein cohomology of odd orthogonal groups

The paper investigates a significant part of the automorphic, in fact of the so-called Eisenstein cohomology of split odd orthogonal groups over Q. The main result provides a description of residual and regular Eisenstein cohomology classes for maximal parabolic Q-subgroups in case of generic cohomological cuspidal automorphic representations of their Levi subgroups. That is, such identifying necessary conditions on these latter representations as well as on the complex parameters in order for the associated Eisenstein series to possibly yield non-trivial classes in the automorphic cohomology.Comment: 21 pages, some minor corrections made, journal reference adde

Holonomy Groups of Complete Flat Pseudo-Riemannian Homogeneous Spaces

We show that a complete flat pseudo-Riemannian homogeneous manifold with non-abelian linear holonomy is of dimension at least 14. Due to an example constructed in a previous article by Oliver Baues and the author, this is a sharp bound. Also, we give a structure theory for the fundamental groups of complete flat pseudo-Riemannian manifolds in dimensions less than 7. Finally, we observe that every finitely generated torsion-free 2-step nilpotent group can be realized as the fundamental group of a complete flat pseudo-Riemannian manifold with abelian linear holonomy.Comment: 16 page

Another look at anomalous J/Psi suppression in Pb+Pb collisions at P/A = 158 GeV/c

A new data presentation is proposed to consider anomalous $J/\Psi$ suppression in Pb + Pb collisions at $P/A=158$ GeV/c. If the inclusive differential cross section with respect to a centrality variable is available, one can plot the yield of J/Psi events per Pb-Pb collision as a function of an estimated squared impact parameter. Both quantities are raw experimental data and have a clear physical meaning. As compared to the usual J/Psi over Drell-Yan ratio, there is a huge gain in statistical accuracy. This presentation could be applied advantageously to many processes in the field of nucleus-nucleus collisions at various energies.Comment: 6 pages, 5 figures, submitted to The European Physical Journal C; minor revisions for final versio