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.

Complete game-theoretic characterization of SIS epidemics protection strategies

Abstract: Defining an optimal protection strategy against viruses, spam propagation or any other kind of contamination process is an important feature for designing new networks and architectures. In this work, we consider decentralized optimal protection strategies when a virus is propagating over a network through a Susceptible Infected Susceptible (SIS) epidemic process. We assume that each node in the network can fully protect itself from infection at a constant cost, or the node can use recovery software, once it is infected. We model our system using a game theoretic framework. Based on this model, we find pure and mixed equilibria, and evaluate the performance of the equilibria by finding the Price of Anarchy (PoA) in several network topologies. Finally, we give numerical illustrations of our results.

The potential of the MAGIC TOM parental accessions to explore the genetic variability in tomato acclimation to repeated cycles of water deficit and recovery

Abstract: Episodes of water deficit (WD) during the crop cycle of tomato may negatively impact plant growth and fruit yield, but they may also improve fruit quality. Moreover, a moderate WD may induce a plant "memory effect" which is known to stimulate plant acclimation and defenses for upcoming stress episodes. The objective of this study was to analyze the positive and negative impacts of repeated episodes of WD at the plant and fruit levels. Three episodes of WD (-38 %, -45 % and -55 % of water supply) followed by three periods of recovery ("WD treatments"), were applied to the 8 parents of the Multi-Parent Advanced Generation Inter-Cross population which offers the largest allelic variability observed in tomato. Predawn and midday water potentials, chlorophyll a fluorescence, growth and fruit quality traits (contents in sugars, acids, carotenoids and ascorbic acid (AsA)) were measured throughout the experiment. Important genotypic variations were observed both at the plant and fruit levels and variations in fruit and leaf traits were found not to be correlated. Overall, the WD treatments were at the origin of important osmotic regulations, reduction of leaf growth, acclimation of photosynthetic functioning, notably through an increase in the chlorophyll content and in the quantum yield of the electron transport flux until PSI acceptors (J0RE1/JABS). The effects on fruit sugar, acid, carotenoid and AsA contents on a dry matter basis ranged from negative to positive to nil depending on genotypes and stress intensity. Three small fruit size accessions were richer in AsA on a fresh matter basis, due to concentration effects. So, fruit quality was improved under WD mainly through concentration effects. On the whole, two accessions, LA1420 and Criollo appeared as interesting genetic resources, cumulating adaptive traits both at the leaf and fruit levels. Our observations show that the complexity involved in plant responses, when considering a broad range of physiological traits and the variability of genotypic effects, represent a true challenge for upcoming studies aiming at taking advantage of, not just dealing with WD.

Ecological restoration by soil transfer: impacts on restored soil profiles and topsoil functions

Abstract: A last resort means to restoring a severely degraded ecosystem can involve soil transfer, especially when destruction of an undegraded system has been previously independently planned. We measured the impact of different soil transfer treatments that varied in vertical and orderly reconstitution of the main soil horizons on the microbial activity and organic matter composition during restoration of a Haplic Cambisol in a steppe ecosystem. There were differences between the topsoil of the reference ecosystem and the soil transfer treatments in terms of physicochemical parameters and microbial activity, but this was not the case when topsoil was not replaced at the soil surface. Three years following restoration, the transferred topsoil treatment, where the three main soil layers were transferred, contained lower particulate organic matter content than the steppe reference soil, despite similarity in potential carbon mineralization. Soil profile descriptions revealed strong differences in overall organization between the transferred soil and the undisturbed steppe soil, particularly with respect to lower biological activity and a lack of connectivity between pedological horizons via the plant root systems and the earthworm activity in the transferred soil. This suggests that soil transfer conducted to retain soil horizons provides good results when the topsoil is transferred, but it may result in altered biological activity, profile morphology, and organic matter content compared with the reference system.