Airborne forward pointing UV Rayleigh lidar for remote clear air turbulence (CAT) detection: system design and performance

A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuations measurement and is thus independent of backscatter from hydrometeors and aerosol particles. The subtle air density fluctuations caused by the turbulent air flow demand exceptionally high stability of the setup and in particular of the detection system. This paper describes an airborne test system for the purpose of demonstrating this technology and turbulence detection method: a high-power UV Rayleigh lidar system is installed on a research aircraft in a forward-looking configuration for use in cruise flight altitudes. Flight test measurements demonstrate this unique lidar system being able to resolve air density fluctuations occurring in light-to-moderate CAT at 5 km or moderate CAT at 10 km distance. A scaling of the determined stability and noise characteristics shows that such performance is adequate for an application in commercial air transport.Comment: 17 pages, 19 figures. Pre-publish to Applied Optics (OSA

A subKelvin scanning probe microscope for the electronic spectroscopy of an individual nano-device

We present a combined scanning force and tunneling microscope working in a dilution refrigerator that is optimized for the study of individual electronic nano-devices. This apparatus is equipped with commercial piezo-electric positioners enabling the displacement of a sample below the probe over several hundred microns at very low temperature, without excessive heating. Atomic force microscopy based on a tuning fork resonator probe is used for cryogenic precise alignment of the tip with an individual device. We demonstrate the local tunneling spectroscopy of a hybrid Josephson junction as a function of its current bias

Crunching Biofilament Rings

We discuss a curious example for the collective mechanical behavior of coupled non-linear monomer units entrapped in a circular filament. Within a simple model we elucidate how multistability of monomer units and exponentially large degeneracy of the filament's ground state emerge as a collective feature of the closed filament. Surprisingly, increasing the monomer frustration, i.e., the bending prestrain within the circular filament, leads to a conformational softening of the system. The phenomenon, that we term polymorphic crunching, is discussed and applied to a possible scenario for membrane tube deformation by switchable dynamin or FtsZ filaments. We find an important role of cooperative inter-unit interaction for efficient ring induced membrane fission

Qualitative Representation of Dynamic Attributes of Trajectories

International audienceTrajectory dynamic characteristics may be a very relevant source of information to analyze the behaviour of moving objects. However, most of existing works on trajectory representation deal only with basic parameters of trajectories, namely space and time. In this paper, we show how some derivatives of the spatio-temporal dimension, e.g. speed, acceleration, direction, may be integrated in trajectory modelling. We address the problem of representing trajectories in a way that qualitative descriptions of trajectories are stored and easily accessed through an ontology called QualiTraj which is also flexible enough to support relevant raw data representation. We validate our proposal with real GPS traces collected from a well-known sports tracking mobile application

A Pearson Effective Potential for Monte-Carlo simulation of quantum confinement effects in various MOSFET architectures

A Pearson Effective Potential model for including quantization effects in the simulation of nanoscale nMOSFETs has been developed. This model, based on a realistic description of the function representing the non zero-size of the electron wave packet, has been used in a Monte-Carlo simulator for bulk, single gate SOI and double-gate SOI devices. In the case of SOI capacitors, the electron density has been computed for a large range of effective field (between 0.1 MV/cm and 1 MV/cm) and for various silicon film thicknesses (between 5 nm and 20 nm). A good agreement with the Schroedinger-Poisson results is obtained both on the total inversion charge and on the electron density profiles. The ability of an Effective Potential approach to accurately reproduce electrostatic quantum confinement effects is clearly demonstrated.Comment: 13 pages, 11 figures, 3 table

Élisabeth Gonzalez, Un prince en son hôtel, Les serviteurs des ducs d’Orléans au XVe siècle

À la différence de l’Hôtel des ducs de Bourgogne, institution stable entre toutes, qui a laissé une documentation considérable, exploitée avec jubilation par les historiens, l’Hôtel d’Orléans n’était pas des plus faciles à étudier ; institution à éclipses, il n’a engendré qu’une documentation fragmentaire et dispersée. Son destin fut en effet singulier : constitué sous Louis 1er entre 1388 et 1392, il fonctionna jusqu’à la mort de ce prince en 1407, en osmose avec l’Hôtel de Charles VI, puisq..

Pierre Riché et Jacques Verger, Des nains sur des épaules de géants. Maîtres et élèves au Moyen Âge

Ce livre, très clairement écrit, est à recommander aux étudiants et à tous les passionnés de Moyen Âge pour de multiples raisons. C’est la première fois, à notre connaissance, qu’un même ouvrage traite à la fois des écoles et des universités médiévales, longtemps considérées comme des domaines séparés. De ce fait, le lecteur peut se faire une opinion sur l’ensemble du système éducatif médiéval et sur sa capacité de reconversion au fil des siècles. Il y a loin, en effet, des écoles presbytéral..

Cultiver son jardin : Jomard à Lozère

Quand mémoire de Lozère rencontre Jomard… L’association Mémoire de Lozère, qui regroupe quelques passionnés soucieux de mieux connaître, préserver et mettre en valeur le riche patrimoine historique et naturel du quartier de Lozère, situé en limite d’Orsay, à l’extrémité ouest de la commune de Palaiseau, fut créée le 2 décembre 2008, dans le prolongement d’un groupe informel précédemment constitué au sein du conseil de quartier de Lozère. La toute première rencontre de Mémoire de Lozère avec E..