University of Avignon

About: University of Avignon is a education organization based out in Avignon, Provence-Alpes-Côte-d'Azur, France. It is known for research contribution in the topics: Population & Speaker recognition. The organization has 1526 authors who have published 3766 publications receiving 88928 citations.

Restoring Brazilian savanna ground layer vegetation by topsoil and hay transfer

Abstract: Tropical grassy biomes have been widely neglected for conservation and, after unplanned land use conversion, ecological restoration becomes urgent. The majority of interventions have been based on the misapplication of forest restoration techniques, because there are no validated techniques to restore the species-rich ground layer. In search for innovative techniques to restore the herbaceous layer of the cerrado vegetation, we carried out an experiment based upon topsoil and hay transfer, in the state of Sao Paulo, Brazil. The restoration treatments were: (1) transfer of topsoil collected at the end of the dry season; (2) topsoil collected at the end of the rainy season; (3) transfer of hay collected at the end of the dry season; (4) topsoil + hay collected at the end of the dry season; and (5) control. We used an old-growth grassland as source of material and as reference ecosystem to assess the efficacy of the restoration techniques applied to an area severely degraded after invasion by African grasses. After 211 days, hay transfer apparently inhibited germination and did not contribute to grassland vegetation recovery. Topsoil transfer, however, was effective at reintroducing herbaceous plants, including target species. The season of topsoil collection mattered: material collected at the end of the rainy season provided better results in terms of density and richness of the restored community than that from the dry season. The remaining challenge is to find sources of topsoil not invaded by exotic grasses in large enough amounts to support restoration initiatives without jeopardizing the source ecosystems.

Globally Minimizing Parabolic Motions in the Newtonian N-body Problem

Abstract: We consider the N-body problem in \({\mathbb {R}^d}\) with the Newtonian potential 1/r. We prove that for every initial configuration xi and for every minimizing normalized central configuration x0, there exists a collision-free parabolic solution starting from xi and asymptotic to x0. This solution is a minimizer in every time interval. The proof exploits the variational structure of the problem, and it consists in finding a convergent subsequence in a family of minimizing trajectories. The hardest part is to show that this solution is parabolic and asymptotic to x0.

A new consistent vehicle routing problem for the transportation of people with disabilities

Abstract: In this article, we address a problem of the transportation of people with disabilities where customers are served on an almost daily basis and expect some consistency in the service. We introduce an original model for the time-consistency of the service, based on so-called time-classes. We then define a new multiday vehicle routing problem VRP that we call the Time-Consistent VRP. We address the solution of this new problem with a large neighborhood search heuristic. Each iteration of the heuristic requires solving a complex VRP with multiple time windows and no waiting time which we tackle with a heuristic branch-and-price method. Computational tests are conducted on benchmark sets and modified real-life instances. Results demonstrate the efficiency of the method and highlight the impact of time-consistency on travel costs. © 2014 Wiley Periodicals, Inc. NETWORKS, Vol. 633, 211-224 2014

Flow-mediated dilation in athletes: influence of aging.

Abstract: Purpose Controversy exists on whether endothelial function is enhanced in athletes. We sought to systematically review the literature and determine whether endothelial function, as assessed by flow-mediated dilation (FMD), is greater in athletes across all ages relative to that in their age-matched counterparts. Methods We conducted a systematic search on MEDLINE, Cochrane, Scopus, and Web of Science since their inceptions until July 2013 for articles evaluating FMD in athletes. A meta-analysis was performed to compare the standardized mean difference (SMD) in FMD of the brachial artery between athletes and age-matched control subjects. Subgroup analyses and meta-regression were used to identify sources of heterogeneity. Results Twenty-one articles were included in this analysis, comprising 530 athletes (452 endurance trained, 49 strength trained, and 29 endurance and strength trained) and 376 control subjects. After data pooling, FMD was higher in athletes than that in control groups (SMD, 0.48; P = 0.008). In subgroup analyses, young athletes ( ;50 yr) showed similar baseline brachial artery diameter (mean difference, 0.04 mm; P = 0.69) and increased FMD (SMD, 0.99; P = 0.0005) compared with those in controls. Conclusions The current meta-analysis provides evidence that master athletes but not young athletes exhibit greater FMD compared with that in age-matched healthy controls, thus suggesting that the association between high levels of exercise training and increased FMD is age dependent.