Rare Sugars: Recent Advances and Their Potential Role in Sustainable Crop Protection

Rare sugars are monosaccharides with a limited availability in the nature and almost unknown biological functions. The use of industrial enzymatic and microbial processes greatly reduced their production costs, making research on these molecules more accessible. Since then, the number of studies on their medical/clinical applications grew and rare sugars emerged as potential candidates to replace conventional sugars in human nutrition thanks to their beneficial health effects. More recently, the potential use of rare sugars in agriculture was also highlighted. However, overviews and critical evaluations on this topic are missing. This review aims to provide the current knowledge about the effects of rare sugars on the organisms of the farming ecosystem, with an emphasis on their mode of action and practical use as an innovative tool for sustainable agriculture. Some rare sugars can impact the plant growth and immune responses by affecting metabolic homeostasis and the hormonal signaling pathways. These properties could be used for the development of new herbicides, plant growth regulators and resistance inducers. Other rare sugars also showed antinutritional properties on some phytopathogens and biocidal activity against some plant pests, highlighting their promising potential for the development of new sustainable pesticides. Their low risk for human health also makes them safe and ecofriendly alternatives to agrochemicals.     

Ordre de Nevanlinna des fonctions sousharmoniques continues en une singularité isolée

Dans ce travail, nous étudions l"ordre de Nevanlinna des solutions de l'équation deSchrödinger u = u , où est une mesure de Kato, positive et radiale. Nous montrons que si ne vérifie pas le principe de Picard, alors toute solution non bornée de u = u est d'ordre infini. En utilisant la théorie de perturbation, l'effilement minimal de M. Brelot et la notion d'ensembles essentiels, nous donnons des conditions necessaires et des conditions suffisantes pour que l'ordre des solutions, non bornées au voisinage d'une singularité, soit infini. Enfin nous prouvons que le comportement des solutions d'une telle équation ne permet pas de caractériser la validité ou non du principe de Picard.     

A Stochastic Game Analysis of the Binary Exponential Backoff Algorithm with Multi-Power Diversity and Transmission Cost

In this paper, we present a game analysis of the Binary Exponential Backoff (BEB), a popular bandwidth allocation mechanism used by a large number of distributed wireless technologies. A Markov chain analysis is used to obtain equilibrium retransmission probabilities and throughput. Numerical results show that when the arrival probability increases, the behavior of mobile stations MSs become more and more aggressive resulting in a global deterioration of the system throughput. We then consider a non-cooperative game framework to study the operation and evaluate the performance of the BEB algorithm when a group of MSs competing with each other to gain access to the wireless channel. We focus our attention to the case when an MS acts selfishly by attempting to gain access to the channel using a higher retransmission probability as a means to increase its own throughput. As a means to improve the system performance, we further explore the use of two transmission mechanisms and policies. First, we introduce the use of multiple power levels (MPLs) for the data transmission. The use of multiple power levels results on a capture effect allowing the receiver to properly decode the message even in the presence of a collision. Under the proposed scheme, named MPL-BEB, the effect of the aggressive behavior, higher transmission probabilities, is diminished since the power level is chosen randomly and independently by each and every station. Second, we introduce a disutility policy for power consumption. The resulting mechanism, named MPL-BEB with costs, is of prime interest in wireless networks composed of battery-powered nodes. Under this scheme aggressive behavior is discouraged since each retransmission translates into the depletion of the energy stored in the battery. Via price of anarchy, our results identify a behavior similar to the well-know prisoner’s dilemma. A non-efficiency of Nash equilibrium is observed for all schemes (BEB, MPL-BEB, MPL-BEB with costs) under heavy traffic with a notable outperformance of MPL-BEB with costs over both MPL-BEB and BEB.     

Estimation de l'erreur pour l'interpolation par des splines de type plaque mince sous tension

In this Note, we give some results on the $L_p$-error estimates and convergence in the Sobolev space for the interpolation by thin splines under tension. To cite this article: A. Bouhamidi, C. R. Acad. Sci. Paris, Ser. I 342 (2006).