327 research outputs found
Spectral projectors on hyperbolic surfaces
In this paper, we prove estimates, where , for spectral
projectors on a wide class of hyperbolic surfaces. More precisely, we consider
projections in small spectral windows on
geometrically finite hyperbolic surfaces of infinite volume. In the convex
cocompact case, we obtain optimal bounds with respect to and ,
up to subpolynomial losses. The proof combines the resolvent bound of
Bourgain-Dyatlov and improved estimates for the Schr\"odinger group (Strichartz
and smoothing estimates) on hyperbolic surfaces.Comment: 46 page
La premiĂšre Ă©lection climatique canadienne? : Ă©tude de lâimpact Ă©lectoral des changements climatique lors de lâĂ©lection canadienne de 2019
Sondage post-Ă©lectoral de l'Ă©lection canadienne de 2019Ce mĂ©moire vise Ă comprendre la place que la lutte aux changements climatiques a occupĂ©e lors de lâĂ©lection fĂ©dĂ©rale de 2019, considĂ©rĂ©e par plusieurs comme ayant dĂ©terminĂ© par lâattitude des Ă©lecteurs Ă propos des changements climatiques. Il analyse la relation entre le comportement Ă©lectoral et les ramifications climatiques, incarnĂ©e par les enjeux de la taxe carbone et les olĂ©oducs, qui clivent la classe politique et qui ont servi dâexplication Ă la suite de la victoire du Parti libĂ©ral du Canada de Justin Trudeau. Certains commentateurs politiques â dâOuest en Est - ont avancĂ© que pour la premiĂšre fois dans lâhistoire canadienne, une Ă©lection canadienne a Ă©tĂ© le thĂ©Ăątre dâun rĂ©fĂ©rendum sur les changements climatiques. Dâautres ont annoncĂ© le grand gagnant de lâĂ©lection ne fĂ»t pas tant le gouvernement sortant de Justin Trudeau, et encore moins la formation conservatrice dĂ©faite dirigĂ©e par Andrew Scheer, mais bien celle de de la taxe carbone adoptĂ©e par le gouvernement fĂ©dĂ©ral dans le Cadre pancanadien sur la croissance propre et les changements climatiques en 2017.This paper aims to understand the place that the climate change took in the 2019 federal election, considered by many to have determined voters' attitudes to climate change. It analyzes the relationship between electoral behavior and climate ramifications, embodied in the carbon tax and oil pipeline issues that split the political class and served as an explanation for the victory of Justin Trudeau's Liberal Party of Canada. Some political commentators from West to East argued that for the first time in Canadian history, a Canadian election was the scene of a referendum on climate change. Others announced that the big winner of the election was notJustin Trudeau's outgoing government, nor the defeated Conservative formation led by Andrew Scheer, but the carbon tax adopted by the federal government in the 2017 Pan-Canadian Framework on Clean Growth and Climate Change
Bayesian Network Modelling the risk analysis of complex socio technical systems
International audienceThe risk analysis of a system is a multidisciplinary process in constant evolution. Indeed, if a few years ago, analyses were limited at the technical level, it is today necessary to consider the system in a global way, by including Human beings and Organisations. But this involves an increasing complexity of the studied system, because of the widening of its limits and the diversity of considered disciplines. This article proposes a method to structure the knowledge in a decisionmaking model
R-MOM: A Component-Based Framework for Interoperable and Adaptive Asynchronous Middleware Systems
International audienceSystems of systems (SoS) are composed of subsystems such as Distributed, Information Technology, Real-Time and Embedded systems. Among distributed systems, Message- Oriented Middleware (MOM) is used by SoS in order to share status information from system elements (component, service, etc.). Often several different MOM technologies are used in one SoS, then interoperability between these MOM is a requirement. In this paper, we present R-MOM, a component-based framework for interoperable and adaptive asynchronous middleware systems. R-MOM provides a reflective component architecture where one MOM functionality is embedded into one component which is modifiable at run-time. Loosely-coupling between reflective components permits to get a fined-personalization of MOM functionalities, such as protocol, encoding rule, Quality of Services (QoS) processing, data production/consumption, description, routing and filtering. Interoperability between integrated protocol functionalities is a consequence of architecture design. R-MOM interoperates with different kinds of MOM, from distributed message queues (Java Message Service, Advanced Message Queueing Protocol, 0MQ) to content-based publish/ subscribe systems (OMG's Data Distribution Service). This paper describes the architectural concepts of the R-MOM framework, discusses its implementation, and evaluates its interoperability capability.Les SystĂšmes de SystĂšmes (SoS) sont composĂ©s de sous-systĂšmes tels que les systĂšmes de type distribuĂ©, IT, temps-rĂ©el et embarquĂ©. Parmi les systĂšmes distribuĂ©s, les intergiciels orientĂ©s message (MOM) sont utilisĂ©s par les SoS dans le but de partager des informations de statut des Ă©lĂ©ments du systĂšmes (composant, service, etc...). Souvent, plusieurs technologies MOM sont utilisĂ©es dans un mĂȘme SoS, et interopĂ©rabilitĂ© entre MOM devient nĂ©cessaire. Dans ce papier, nous prĂ©sentons R-MOM, un canevas basĂ© sur l'approche composant pour les intergiciels interopĂ©rables, adaptatifs et asynchrones. R-MOM offre une architecture Ă composants rĂ©flexif, oĂč une fonctionalitĂ© d'un MOM est embarquĂ©e dans un composant qui est modifiable durant son exĂ©cution. Le couplage lĂąche entre les composants rĂ©flexif permet de jouir d'une personnalisation fine sur les fonctionalitĂ©s MOM visĂ©es, comme le protocole, la rĂšgle d'encodage, le support des qualitĂ©s de service, la production et consommation, la description, le routage et le filtrage des donnĂ©es. L'interopĂ©rabilitĂ© entre les fonctionnalitĂ©s protocolaire intĂ©grĂ©es est une consĂ©quence du choix de conception de l'architecture. R-MOM est interopĂ©rable avec diffĂ©rent types de MOM, depuis les queues de message distribuĂ© (Java Message Service, Advanced Message Queueing Protocol, 0MQ) jusqu'aux systĂšmes de publication/souscription basĂ©es sur le contenu (Service de Distribution de DonnĂ©es de l'OMG). Ce papier papier dĂ©crit les concepts d'architecture du canevas R-MOM, discute son implĂ©mentation et Ă©value sa capacitĂ© d'interopĂ©rabilitĂ©
Methodological developments for probabilistic risk analyses of socio-technical systems
International audienceNowadays, the risk analysis of critical systems cannot be focused only on a technical point of view. Indeed, several major accidents have changed this initial way of thinking. As a result, there exist numerous methods that allow to study risks by considering on the main system resources: the technical process, the operator constraining this process, and the organisation conditioning human actions. However, few works propose to jointly use these different methods to study risks in a global approach. In that way, this paper presents a methodology, which is under development between CRAN, EDF and INERIS, allowing an integration of these different methods to probabilistically estimate risks. This integration is based on unification and structuring knowledge concepts; and the quantitative aspect is achieved through the use of Bayesian Networks. An application of this methodology, on an industrial case, demonstrates its feasibility and concludes on model capacities, which are about the necessary consideration of the whole causes for a system weakness treatment, and the classification of these contributors considering their criticality for this system. This tool can thus be used to help decision makers to prioritise their actions
Electrochemical measurements of the kinetics of inhibition of two FeFe hydrogenases by O2 demonstrate that the reaction is partly reversible
International audienceThe mechanism of reaction of FeFe hydrogenases with oxygen has been debated. It is complex, apparently very dependent on the details of the protein structure, and difficult to study using conventional kinetic techniques. Here we build on our recent work on the anaerobic inactivation of the enzyme [Fourmond et al, Nat. Chem. 4 336 (2014)] to propose and apply a new method for studying this reaction. Using electrochemical measurements of the turnover rate of hydrogenase, we could resolve the first steps of the inhibition reaction and accurately determine their rates. We show that the two most studied FeFe hydrogenases, from Chlamydomonas reinhardtii and Clostridium acetobutylicum, react with O2 according to the same mechanism, despite the fact that the former is much more O2 sensitive than the latter. Unlike often assumed, both enzymes are reversibly inhibited by a short exposure to O2. This will have to be considered to elucidate the mechanism of inhibition, before any prediction can be made regarding which mutations will improve oxygen resistance. We hope that the approach described herein will prove useful in this respect
VCSEL Based on InAs Quantum-Dashes With a Lasing Operation Over a 117-nm Wavelength Span
International audienceWe report an InP based vertical cavity surface emitting laser (VCSEL) achieving a lasing operation between 1529 and 1646 nm. This optically-pumped VCSEL includes a wide-gain bandwidth active region based on InAs quantum dashes and wideband dielectric Bragg mirrors. Based on a wedge microcavity design, we obtain a spatial dependence of the resonant wavelength along the wafer, enabling thus to monitor the gain material bandwidth. We demonstrate a 117 nm continuous wavelength variation of the VCSEL emission, a consequence of the important and wide gain afforded by the use of optimized quantum dashes
Tests of achromatic phase shifters performed on the SYNAPSE test bench: a progress report
The achromatic phase shifter (APS) is a component of the Bracewell nulling
interferometer studied in preparation for future space missions (viz.
Darwin/TPF-I) focusing on spectroscopic study of Earth-like exo-planets.
Several possible designs of such an optical subsystem exist. Four approaches
were selected for further study. Thales Alenia Space developed a dielectric
prism APS. A focus crossing APS prototype was developed by the OCA, Nice,
France. A field reversal APS prototype was prepared by the MPIA in Heidelberg,
Germany. Centre Spatial de Li\`ege develops a concept based on Fresnel's
rhombs. This paper presents a progress report on the current work aiming at
evaluating these prototypes on the SYNAPSE test bench at the Institut
d'Astrophysique Spatiale in Orsay, France
VCSEL à fils quantiques présentant une émission laser de 1647 à 1542 nm
National audienceLes lasers Ă cavitĂ© verticale Ă©mettant par la surface (VCSEL) prĂ©sentent de grands intĂ©rĂȘts pour des applications variĂ©es (tĂ©lĂ©communication, capteurs, ..), d'autant plus si ces derniers s'avĂšrent stables et accordables en longueur d'onde. Au-delĂ du procĂ©dĂ© technologique utilisĂ©, cette derniĂšre propriĂ©tĂ© est aussi trĂšs limitĂ©e par l'extension du gain spectral de la zone active. Nous prĂ©sentons ici la rĂ©alisation d'un VCSEL Ă©mettant Ă 1.55 ÎŒm, et prĂ©sentant une Ă©mission laser sur une plage en longueur d'onde de 105 nm
VCSEL à fils quantiques présentant une émission laser de 1647 à 1542 nm
National audienceLes lasers Ă cavitĂ© verticale Ă©mettant par la surface (VCSEL) prĂ©sentent de grands intĂ©rĂȘts pour des applications variĂ©es (tĂ©lĂ©communication, capteurs, ..), d'autant plus si ces derniers s'avĂšrent stables et accordables en longueur d'onde. Au-delĂ du procĂ©dĂ© technologique utilisĂ©, cette derniĂšre propriĂ©tĂ© est aussi trĂšs limitĂ©e par l'extension du gain spectral de la zone active. Nous prĂ©sentons ici la rĂ©alisation d'un VCSEL Ă©mettant Ă 1.55 ÎŒm, et prĂ©sentant une Ă©mission laser sur une plage en longueur d'onde de 105 nm
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