Adaptive Speckle Imaging Interferometry: a new technique for the analysis of microstructure dynamics, drying processes and coating formation

We describe an extension of multi-speckle diffusing wave spectroscopy adapted to follow the non-stationary microscopic dynamics in drying films and coatings in a very reactive way and with a high dynamic range. We call this technique "Adaptive Speckle Imaging Interferometry". We introduce an efficient tool, the inter-image distance, to evaluate the speckle dynamics, and the concept of "speckle rate" (SR, in Hz) to quantify this dynamics. The adaptive algorithm plots a simple kinetics, the time evolution of the SR, providing a non-invasive characterization of drying phenomena. A new commercial instrument, called HORUS(R), based on ASII and specialized in the analysis of film formation and drying processes is presented.Comment: 11 pages, 4 figure

Formal Safety and Security Assessment of an Avionic Architecture with Alloy

We propose an approach based on Alloy to formally model and assess a system architecture with respect to safety and security requirements. We illustrate this approach by considering as a case study an avionic system developed by Thales, which provides guidance to aircraft. We show how to define in Alloy a metamodel of avionic architectures with a focus on failure propagations. We then express the specific architecture of the case study in Alloy. Finally, we express and check properties that refer to the robustness of the architecture to failures and attacks.Comment: In Proceedings ESSS 2014, arXiv:1405.055

Contribution à l'assurance fiabilité de filières HEMTs à base de GaN sur substrat SiC : caractérisation électrique approfondie et modélisaton des effets parasites

This work is incorporated within the framework of the qualification of UMS GaNtechnologies and more particularly of the GH25 technology, and aims to support thedevelopment of UMS GaN based technologies. The first part of this report deals withAlGaN/GaN HEMT generality. The second part is dedicated to the description of the UMStechnologies GH50 and GH25. Passive components of GH25 technology have beencharacterized through electrical and thermal measurement, and then breakdown measurementsusing a drain current injection technique have been carried out on GH50 HEMT in order toevaluate the safe operating area of these devices. The third part is dedicated to the study of theparasitic effects observed on the two technologies GH50 and GH25. Each of these parasiticeffects is described and fully characterized. The last part of this work focuses on the study ofthe GH25 technology. Technological variations are first introduced, and then results ofaccelerated aging test carried out at UMS are analyzed to evaluate their impact on thereliability of the GH25 technology and to identify wear out mechanism and parasitic effects.Ces travaux s'inscrivent dans le cadre de la qualification des technologies GaN de UMS et plus particulièrement celle de la technologie GH25, et a pour objectif d’apporter un soutien direct au développement des technologies UMS à base de GaN. Le premier chapitre traite des généralités sur les HEMTs AlGaN/GaN. Le deuxième chapitre est consacré à la description des technologies GH50 et GH25 de UMS. Les éléments passifs de la technologie GH25 ont été caractérisés électriquement et thermiquement, puis des mesures de claquage utilisant une technique d’injection de courant de drain ont été mises en oeuvre sur des HEMTs de la technologie GH50 afin d’évaluer l'aire de sécurité de fonctionnement. Le troisième chapitre est dédié à l'étude des effets parasites rencontrés sur les deux technologies GH50 et GH25.Chacun des effets parasites est décrit puis caractérisé de façon approfondie. Le dernier chapitre se concentre sur l'étude de la fiabilité de la technologie GH25. Après avoir présenté les différentes variantes technologiques, les résultats des tests de vieillissement accéléré mis en oeuvre à UMS sont analysés afin d'évaluer leur impact sur la fiabilité de la technologieGH25 et d’identifier les mécanismes de dégradation et les effets parasites

Réforme des autorisations de prélèvement dans le bassin Adour-Garonne : impacts sur l'économie agricole

La réglementation française remet à plat les autorisations de prélèvements d'eau pour l'irrigation, dans un objectif de retour à l'équilibre ressources/besoins d'ici 2014 à 2021. Dans le sudouest, où une majorité du territoire est considérée comme déficitaire en eau mais où l'irrigation est très présente, cette réforme impliquera une baisse des volumes actuellement attribués. La présente étude a eu pour objectif d'évaluer l'impact de cette baisse sur l'économie agricole. Elle a été effectuée à l'échelle de six territoires en simulant les pertes en marge brute ou en excédent brut d'exploitation, avec ou sans mesures d'accompagnement. La combinaison de ces mesures permet, dans la majorité des cas, de réduire très significativement voire d'annuler ces pertes. Parmi ces mesures, les plus efficaces sont la création d'ouvrages de stockage et l'allocation prioritaire de quotas d'eau aux cultures à forte valeur ajoutée (arboriculture, maraichage, semences). / Water withdrawal policy for irrigation is reformed by the French legislation for a return to a balance between resources and needs in 2014 to 2021. Irrigation is largely developed in south-western France, where most of the territory faced structural water deficits. This policy change will decrease the available water for irrigation. The aim of this study was to assess the impact of this reform on the farming economy. It has been conducted on six watershed where economic losses have been simulated, using or not support measures. For most of cases, the combination of these measures lead to a significant decrease or a cancel of the losses. Among these measures, the most effective are the investment in water storage, and the prior water reallocation for high added value crops (tree crops, vegetable growing, seeds crops)

Film formation analysis by diffusive wave spectroscopy

The thin layer analysis is very important for several sectors of industry. Indeed, environmental laws and improvement of performances lead the manufacturers to innovate in the field of coatings and paints. Several classical techniques of characterization (TGA, DMA, etc.) used with this intention do not allow to perform the analysis in situ and are often long and tedious to set up. We propose to solve this problem with a newoptical process. Its technology based on multi-speckle diffusivewave spectroscopy (MS-DWS) allows making real-time analysis in a non-destructive way thanks to an optical measurement. The aim of this work is to highlight correlations between this new technology and the classical methods of analysis. Two film forming polymeric materials were studied, a polydimethylsiloxane (PDMS) and a commercial paint based on an aqueous dispersion of acrylic copolymers. The PDMSwas chosen for the simplicity of its film forming process and is used as model. The paint having a more complex drying mechanism enables to complete this study

Dependence of the spike-triggered average voltage on membrane response properties

The spike-triggered average voltage (STV) is an experimentally measurable quantity that is determined by both the membrane response properties and the statistics of the synaptic drive. Here, the form of the STV is modelled for neurons with three distinct types of subthreshold dynamics; passive decay, h-current sag, and damped oscillations. Analytical expressions for the STV are first obtained in the low-noise limit, identifying how the subthreshold dynamics of the cell affect its form. A second result is then derived that captures the power-law behaviour of the STV near the spike threshold

Extracting non-linear integrate-and-fire models from experimental data using dynamic I–V curves

The dynamic I–V curve method was recently introduced for the efficient experimental generation of reduced neuron models. The method extracts the response properties of a neuron while it is subject to a naturalistic stimulus that mimics in vivo-like fluctuating synaptic drive. The resulting history-dependent, transmembrane current is then projected onto a one-dimensional current–voltage relation that provides the basis for a tractable non-linear integrate-and-fire model. An attractive feature of the method is that it can be used in spike-triggered mode to quantify the distinct patterns of post-spike refractoriness seen in different classes of cortical neuron. The method is first illustrated using a conductance-based model and is then applied experimentally to generate reduced models of cortical layer-5 pyramidal cells and interneurons, in injected-current and injected- conductance protocols. The resulting low-dimensional neuron models—of the refractory exponential integrate-and-fire type—provide highly accurate predictions for spike-times. The method therefore provides a useful tool for the construction of tractable models and rapid experimental classification of cortical neurons

Quantitative trait loci linked to PRNP gene controlling health and production traits in INRA 401 sheep

In this study, the potential association of PrP genotypes with health and productive traits was investigated. Data were recorded on animals of the INRA 401 breed from the Bourges-La Sapinière INRA experimental farm. The population consisted of 30 rams and 852 ewes, which produced 1310 lambs. The animals were categorized into three PrP genotype classes: ARR homozygous, ARR heterozygous, and animals without any ARR allele. Two analyses differing in the approach considered were carried out. Firstly, the potential association of the PrP genotype with disease (Salmonella resistance) and production (wool and carcass) traits was studied. The data used included 1042, 1043 and 1013 genotyped animals for the Salmonella resistance, wool and carcass traits, respectively. The different traits were analyzed using an animal model, where the PrP genotype effect was included as a fixed effect. Association analyses do not indicate any evidence of an effect of PrP genotypes on traits studied in this breed. Secondly, a quantitative trait loci (QTL) detection approach using the PRNP gene as a marker was applied on ovine chromosome 13. Interval mapping was used. Evidence for one QTL affecting mean fiber diameter was found at 25 cM from the PRNP gene. However, a linkage between PRNP and this QTL does not imply unfavorable linkage disequilibrium for PRNP selection purposes

Perception of categories: from coding efficiency to reaction times

Reaction-times in perceptual tasks are the subject of many experimental and theoretical studies. With the neural decision making process as main focus, most of these works concern discrete (typically binary) choice tasks, implying the identification of the stimulus as an exemplar of a category. Here we address issues specific to the perception of categories (e.g. vowels, familiar faces, ...), making a clear distinction between identifying a category (an element of a discrete set) and estimating a continuous parameter (such as a direction). We exhibit a link between optimal Bayesian decoding and coding efficiency, the latter being measured by the mutual information between the discrete category set and the neural activity. We characterize the properties of the best estimator of the likelihood of the category, when this estimator takes its inputs from a large population of stimulus-specific coding cells. Adopting the diffusion-to-bound approach to model the decisional process, this allows to relate analytically the bias and variance of the diffusion process underlying decision making to macroscopic quantities that are behaviorally measurable. A major consequence is the existence of a quantitative link between reaction times and discrimination accuracy. The resulting analytical expression of mean reaction times during an identification task accounts for empirical facts, both qualitatively (e.g. more time is needed to identify a category from a stimulus at the boundary compared to a stimulus lying within a category), and quantitatively (working on published experimental data on phoneme identification tasks)