High Refractive Index Silicone Gels for Simultaneous Total Internal Reflection Fluorescence and Traction Force Microscopy of Adherent Cells

Substrate rigidity profoundly impacts cellular behaviors such as migration, gene expression, and cell fate. Total Internal Reflection Fluorescence (TIRF) microscopy enables selective visualization of the dynamics of substrate adhesions, vesicle trafficking, and biochemical signaling at the cell-substrate interface. Here we apply high-refractive-index silicone gels to perform TIRF microscopy on substrates with a wide range of physiological elastic moduli and simultaneously measure traction forces exerted by cells on the substrate

Analyse et modélisation des champs de précipitation pour l'optimisation des liaisons micro-ondes terre/espace

TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocSudocFranceF

Spatio-temporal modelling of rain field and of associated liquid water field (application to earth space propagation studies)

Ce manuscrit réunit les résultats d'études consacrées à la modélisation spatio-temporelle des affaiblissements de propagation dans la troposphere. La modélisation de ces affaiblissements est utile pour l'optimisation et le dimensionnement des dispositifs adaptatifs de gestion de la ressource des satellites de télécommunication opérant en bande Ka ou Q/V. Ce manuscrit est organisé autour de cinq articles de revues. Les deux premières contributions sont dédiées à la modélisation des distributions statistiques de contenus troposphériques en vapeur d'eau et en eau liquide à partir respectivement de mesures radiométriques et de bases de données climatiques. La troisième étude touche à l'évaluation des performances d'un système utilisant la diversité de site à partir de données de radar météorologique ; une étude de l'advection des champs précipitations et de son paramétrage par des sorties de modèles de prévision météorologique est également entreprise. Le quatrième article vise à établir une expression analytique de la distribution de la fraction d'une zone, d'une taille comparable à celle d'un faisceau satellite, affectée par la pluie ; ce modèle est établi en assimilant les champs de précipitations à des champs aléatoires. Le formalisme des champs aléatoires est repris dans le cinquième article qui propose une modélisation spatio-temporelle des champs de précipitations et des atténuations sous-jacentes à hautes résolutions et à l'échelle d'une couverture satellite continentale.TOULOUSE-ISAE (315552318) / SudocSudocFranceF

Characterization and modeling of tropospheric propagation at high latitudes for satcom systems

International audienceThe work presented in this paper aims at developing and evaluating the potentialities of a highresolution meteorological model coupled with an electromagnetic module to produce reliable tropospheric attenuation statistics at polar latitudes. To do so, an Atmospheric Numerical Simulator (ANS) based on the high-resolution weather model PWRF-ARW dedicated to polar latitudes is used to generate 3D daily states of the atmosphere in Svalbard (Norway, 80° north latitude) at high spatial (2×2km²) and temporal (5mn) resolutions. Because of considerable computational times, this preliminary work focuses on the simulation of a single day (2017/02/21) during which typical polar precipitations occur. First, the PWRF meteorological outputs relevant for propagation purposes (3D atmospheric datacubes) are compared with reference reanalysis data (Arome-Arctic, CARRA, ERA5) as well as meteorological measurements collected during the THOR7 propagation experiment based on the Svalbard archipelago. Second, an electromagnetic module is used to convert the PWRF meteorological output datacubes into tropospheric attenuation time series simulating the link at Ka band between the THOR7 beacon and the SvalSat teleport. These are compared with the experimental time series collected during the THOR7 propagation experiment. Synthetic attenuation statistics are also produced for that specific day and compared to the experimental statistics derived from the THOR7 propagation experiment. On the 2017/02/21, the results show a good agreement between PWRF outputs and the other meteorological data sources. Additionally, if the synthetic attenuation times series reproduces quite well the experimental time series dynamics, the statistical analysis reveals overestimations that could be explained by either an approximative modeling of the hydrometeors in mixed-phase or wrong predicted hydrometeors contents

Characterization and modeling of tropospheric propagation at high latitudes for satcom systems

International audienceThe work presented in this paper aims at developing and evaluating the potentialities of a highresolution meteorological model coupled with an electromagnetic module to produce reliable tropospheric attenuation statistics at polar latitudes. To do so, an Atmospheric Numerical Simulator (ANS) based on the high-resolution weather model PWRF-ARW dedicated to polar latitudes is used to generate 3D daily states of the atmosphere in Svalbard (Norway, 80° north latitude) at high spatial (2×2km²) and temporal (5mn) resolutions. Because of considerable computational times, this preliminary work focuses on the simulation of a single day (2017/02/21) during which typical polar precipitations occur. First, the PWRF meteorological outputs relevant for propagation purposes (3D atmospheric datacubes) are compared with reference reanalysis data (Arome-Arctic, CARRA, ERA5) as well as meteorological measurements collected during the THOR7 propagation experiment based on the Svalbard archipelago. Second, an electromagnetic module is used to convert the PWRF meteorological output datacubes into tropospheric attenuation time series simulating the link at Ka band between the THOR7 beacon and the SvalSat teleport. These are compared with the experimental time series collected during the THOR7 propagation experiment. Synthetic attenuation statistics are also produced for that specific day and compared to the experimental statistics derived from the THOR7 propagation experiment. On the 2017/02/21, the results show a good agreement between PWRF outputs and the other meteorological data sources. Additionally, if the synthetic attenuation times series reproduces quite well the experimental time series dynamics, the statistical analysis reveals overestimations that could be explained by either an approximative modeling of the hydrometeors in mixed-phase or wrong predicted hydrometeors contents

A Large-Scale Space-Time Stochastic Simulation Tool of Rain Attenuation for the Design and Optimization of Adaptive Satellite Communication Systems Operating between 10 and 50 GHz

International audienceThe design and optimization of propagation impairment techniques for space telecommunication systems operating at frequencies above 20 GHz require a precise knowledge of the propagation channel both in space and time. For that purpose, space-time channel models have to be developed. In this paper the description of a model for the simulation of long-term rain attenuation time series correlated both in space and time is described. It relies on the definition of a stochastic rain field simulator constrained by the rain amount outputs of the ERA-40 reanalysis meteorological database. With this methodology, realistic propagation conditions can be generated at the scale of satellite coverage (i.e., over Europe or USA) for many years. To increase the temporal resolution, a stochastic interpolation algorithm is used to generate spatially correlated time series sampled at 1 Hz, providing that way valuable inputs for the study of the performances of propagation impairment techniques required for adaptive SatCom systems operating at Ka band and above

Caractérisation et modélisation de la scintillation ionosphérique sur les signaux GNSS en zone polaire et équatoriale

International audienceLa présente communication décrit un ensemble de travaux effectués à l'ONERA en partenariat avec l'université Paul Sabatier et le CNES sur la propagation électromagnétique à travers l'ionosphère turbulente. Le problème direct de la propagation à travers l'ionosphère turbulente est tout d'abord traité par le développement de modèles basés sur une description statistique du milieu ionosphérique inhomogène. Puis à partir du formalisme asymptotique développé, des mesures GNSS sont inversées pour obtenir des paramètres décrivant le milieu. Cette approche a été testée sur la base de données SAGAIE en zone équatoriale. Enfin un modèle dédié à la prédiction de la scintillation ionosphérique à hautes latitudes, régressé sur une base de données norvégienne acquises sur un cycle solaire, est proposé

Intervention Modelling at High-energy Particle Accelerators

An important aspect in the design and operation of high-energy particle accelerators is the planning of maintenance interventions. In the planning of these interventions, optimizing the exposure of the maintenance workers to ionizing radiation is a core issue. In this context, we have addressed the need for an interactive visual software tool. The intervention planning has been modelled mathematically. A proof-of-concept software tool has been implemented using this model, providing interactive visualization of facilities and radiation levels, tools for trajectory planning and automatic calculation of the expected integrated equivalent radiation dose. We explore the use of the software using a large experimental hall at CERN as a case study. Interactive visualization of the facilities and radiation levels, tools for interactive trajectory planning as well as automatic calculation of the expected integrated equivalent dose contracted during an intervention are explored. The obtained results prove the relevance of the developed methodology and software tool and demonstrate, among others, a better exploitation of the simulation data, leading to a potential accuracy gain

The practical use of an interactive visualisation and planning tool for intervention planning in particle accelerator environments with ionizing radiation Nuclear Inst.

International audienc