Unit-cell for dual-circular polarisation reflectarrays

International audience—A new unit-cell composed of two layers for dual-CP reflectarrays is proposed for the first time with the unique capability to reflect independently and simultaneously the two incident circular polarisations at the same frequency. The experimental results demonstrate that this unit-cell exhibits a 3.8% bandwidth around 8.4 GHz for a phase resolution better than 1.92 bits in LHCP and in RHCP. As a first step towards a reflectarray in dual-CP, this innovative unit-cell is studied in an array configuration. To increase the value of the maximum incidence angle up to 30°, a matching dielectric layer is placed over the cell

Application de la borne de Cramer-Rao dans le cas de systèmes antennaires complexes de goniométrie

Généralement, la borne de Cramer-Rao des directions d'arrivée de signaux sur un réseau de capteurs est calculée de façon théorique [1] [2] [3]. Or dès que l'on désire effectuer une application numérique de la borne de Cramer-Rao pour un système donné, on est souvent amené à effectuer des suppositions et/ou des simplifications. En effet, il est souvent très difficile de tenir compte et de modéliser l'environnement et les différents phénomènes pouvant perturber le réseau de capteurs, comme le couplage entre antennes, l'influence d'un porteur (mat ou véhicule) en termes de diffraction, de réflexion ou même la présence d'un sol. Dans ce travail, nous utilisons un logiciel de simulation électromagnétique pour estimer l'impact de l'environnement réel sur le vecteur direction d'un système antennaire complexe de goniométrie. La borne de Cramer-Rao déterministe des directions d'arrivée de signaux est ensuite déterminée pour le réseau de capteurs de goniométrie soumis à des perturbations. Les résultats montrent que la précision dépend fortement de la prise en compte des couplages et perturbations du système antennaire. On montre ainsi que l'environnement a un impact non négligeable et que l'on peut calculer une borne de Cramer Rao des directions d'arrivée plus réaliste et ainsi optimiser dans certains cas le système antennaire de goniométrie en fonction de son environnement

Computer Simulation of Cellular Patterning Within the Drosophila Pupal Eye

We present a computer simulation and associated experimental validation of assembly of glial-like support cells into the interweaving hexagonal lattice that spans the Drosophila pupal eye. This process of cell movements organizes the ommatidial array into a functional pattern. Unlike earlier simulations that focused on the arrangements of cells within individual ommatidia, here we examine the local movements that lead to large-scale organization of the emerging eye field. Simulations based on our experimental observations of cell adhesion, cell death, and cell movement successfully patterned a tracing of an emerging wild-type pupal eye. Surprisingly, altering cell adhesion had only a mild effect on patterning, contradicting our previous hypothesis that the patterning was primarily the result of preferential adhesion between IRM-class surface proteins. Instead, our simulations highlighted the importance of programmed cell death (PCD) as well as a previously unappreciated variable: the expansion of cells' apical surface areas, which promoted rearrangement of neighboring cells. We tested this prediction experimentally by preventing expansion in the apical area of individual cells: patterning was disrupted in a manner predicted by our simulations. Our work demonstrates the value of combining computer simulation with in vivo experiments to uncover novel mechanisms that are perpetuated throughout the eye field. It also demonstrates the utility of the Glazier–Graner–Hogeweg model (GGH) for modeling the links between local cellular interactions and emergent properties of developing epithelia as well as predicting unanticipated results in vivo

In silico toxicology protocols

The present publication surveys several applications of in silico (i.e., computational) toxicology approaches across different industries and institutions. It highlights the need to develop standardized protocols when conducting toxicity-related predictions. This contribution articulates the information needed for protocols to support in silico predictions for major toxicological endpoints of concern (e.g., genetic toxicity, carcinogenicity, acute toxicity, reproductive toxicity, developmental toxicity) across several industries and regulatory bodies. Such novel in silico toxicology (IST) protocols, when fully developed and implemented, will ensure in silico toxicological assessments are performed and evaluated in a consistent, reproducible, and well-documented manner across industries and regulatory bodies to support wider uptake and acceptance of the approaches. The development of IST protocols is an initiative developed through a collaboration among an international consortium to reflect the state-of-the-art in in silico toxicology for hazard identification and characterization. A general outline for describing the development of such protocols is included and it is based on in silico predictions and/or available experimental data for a defined series of relevant toxicological effects or mechanisms. The publication presents a novel approach for determining the reliability of in silico predictions alongside experimental data. In addition, we discuss how to determine the level of confidence in the assessment based on the relevance and reliability of the information

Experimental validation of an isoflux Earth coverage with a bimode ARMA antenna on a nanosatellite

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Miniaturization of a Circular Polarized Antenna using Ferrite Materials

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De l'Odyssee a l'Iliade: stratagemes et competences pratiques en ethnomarketing

International audienceEthnomarketing approach represents an interesting renewal for consumer research. Methodological and epistemological particularities of ethnomarketing, associated with the Consumer Culture Theory (CCT), can constrain researchers to mobilize stratagems and bring them to deploy ingenious efforts to get into, practice and restore the ground atmosphere. Although those means account for the “tricks” of this grounded approach, they are rarely highlighted. Pursuing a pedagogic goal, this paper exposes for marketing researchers willing to explore this approach, a large number of cases and solutions allowing them to avoid some obstacles.La démarche ethnomarketing constitue un renouvellement intéressant dans l’étude du comportement du consommateur. Les particularités méthodologiques et épistémologiques de cette démarche, relevant de la Consumer Culture Theory (CCT), peuvent contraindre les chercheurs à recourir à des stratagèmes et les amener à déployer des efforts d’ingéniosité pour accéder, pratiquer et restituer le terrain. Rarement mis en transparence, mais constituant pourtant les « ficelles » de cette méthode de terrain, ces recours sont exposés ici dans une visée pédagogique pour les chercheurs en marketing souhaitant investir cette approche, en leur proposant des solutions leur permettant de contourner certains obstacles