Risque et décisions en gestion de l'eau. Essai d'analyse de la rationalité du dialogue entre hydrologue et gestionnaire. [Tribune libre / Article bilingue]

Le concept de risque, trop souvent imprécis, est analysé et un essai de définition rationnelle est tenté pour tenir compte à la fois des aspects de probabilité et de conséquences dommageables. On montre que toute analyse de risque en sciences de l'eau doit résulter d'un dialogue entre hydrologue et gestionnaire qui doit respecter des critères de clarté , d'efficacité et de cohérence. On insiste particulièrement sur la nécessaire prise en compte par l'hydrologue d'une expression, même simplifiée, des conséquences dommageables réelles pour le gestionnaire ou les membres de la cible du risque.The often vaguely defined concept of risk is analyzed and an attempt is made to provide a rational definition which embeds both probabilistic aspects and consequences associated with decisions. Any risk analysis in the field of water resources involves a dialogue between the hydrologist and the decision-maker, a dialogue which should be clear, eflicient, and coherent. We insist inparticular on the need for the hydrologist to use an expression, even simplified, of the actual damage potential, by the decision- maker or the people at risk

Les incertitudes hydrologiques dans les problèmes de dimensionnement d'ouvrages. Valeur des informations locales et spatiales

Le présent article a pour but de montrer l'importance dune analyse intégrée des problèmes d'estimation hydrologique et des problèmes de décisions d'aménagements pour tenir compte rationnellement des diverses incertitudes intervenant dans ces problèmes. La méthode d'analyse est basée sur les techniques bayesiennes qui permettent des évaluations économiques comparées des divers types d'informations locales ou régionales mobilisées. Un cas d'application schématique est présenté.This paper aims to show the importance of an integrated analysis of hydrological problems of estimation and of decision in water resource fields. Such an analysis is necessary to take into account the various uncertainties involved. The analysis is based on bayesian techniques which allow comparisons between the economical values of various types of information. This information can be both local and regional. A schematic example is presented

Few Graphene layer/Carbon-Nanotube composite Grown at CMOS-compatible Temperature

We investigate the growth of the recently demonstrated composite material composed of vertically aligned carbon nanotubes capped by few graphene layers. We show that the carbon nanotubes grow epitaxially under the few graphene layers. By using a catalyst and gaseous carbon precursor different from those used originally we establish that such unconventional growth mode is not specific to a precise choice of catalyst-precursor couple. Furthermore, the composite can be grown using catalyst and temperatures compatible with CMOS processing (T < 450\degree C).Comment: 4 pages, 4 figure

The production deployment of IPv6 on WLCG

The world is rapidly running out of IPv4 addresses; the number of IPv6 end systems connected to the internet is increasing; WLCG and the LHC experiments may soon have access to worker nodes and/or virtual machines (VMs) possessing only an IPv6 routable address. The HEPiX IPv6 Working Group has been investigating, testing and planning for dual-stack services on WLCG for several years. Following feedback from our working group, many of the storage technologies in use on WLCG have recently been made IPv6-capable. This paper presents the IPv6 requirements, tests and plans of the LHC experiments together with the tests performed on the group's IPv6 test-bed. This is primarily aimed at IPv6-only worker nodes or VMs accessing several different implementations of a global dual-stack federated storage service. Finally the plans for deployment of production dual-stack WLCG services are presented

Level attraction in a microwave optomechanical circuit

Level repulsion - the opening of a gap between two degenerate modes due to coupling - is ubiquitous anywhere from solid state theory to quantum chemistry. In contrast, if one mode has negative energy, the mode frequencies attract instead. They converge and develop imaginary components, leading to an instability; an exceptional point marks the transition. This, however, only occurs if the dissipation rates of the two modes are comparable. Here we expose a theoretical framework for the general phenomenon and realize it experimentally through engineered dissipation in a multimode superconducting microwave optomechanical circuit. Level attraction is observed for a mechanical oscillator and a superconducting microwave cavity, while an auxiliary cavity is used for sideband cooling. Two exceptional points are demonstrated that could be exploited for their topological properties.Comment: 5 pages, 4 figures; includes Supplementary informatio