Micro-Channel Plate Detectors Based on Hydrogenated Amorphous Silicon

A new type of micro-channel plate detector based on hydrogenated amorphous silicon is proposed which overcomes the fabrication and performance issues of glass or bulk silicon ones. This new type of detectors consists in 80-100 μm thick layers of amorphous silicon which are micro-machined by deep reactive ion etching to form the channels. This paper focuses on the structure and fabrication process and presents first results obtained with test devices on electron detection which demonstrate amplification effects. Fabrication and performance issues are also discussed

DAMP HEAT STABILITY OF TRANSPARENT CONDUCTIVE ZINC OXIDES: ROLE OF ENCAPSULANTS AND PROTECTIVE LAYERS

The mechanisms and environmental influences that cause photovoltaic modules performance degradation are poorly understood, but it is well known that water vapour is deeply implicated in the degradation process. Indeed, some layers and interfaces of thin film modules can be moisture sensitive and depending on the processing conditions, they degrade after exposure to damp heat conditions (85°C, 85% relative humidity) [1]. Transparent conductive oxides (TCO), as used in CIGS or thin silicon film cells play a particular role linked to reliability issues. We showed recently that low-pressure chemical vapour deposition zinc oxide (LPCVD ZnO) can withstand damp heat test even without encapsulant providing doping of the ZnO is high enough, though this is unfavourable for free carrier absorption (reduction of spectral response in the infrared part) [2]. Reduction of doping leads to improved optical properties but needs therefore an optimized encapsulation strategy to avoid the deterioration of the TCO conductivity. In previous work, the degradation of LPCVD ZnO used in thin-film silicon solar cells was investigated [3]. It was shown that the decrease of the ZnO conductivity was essentially due to the humidity increasing inside the encapsulant. However other effects take part in the degradation process and remained yet unexplained. In this paper we will report on several other possible sources of degradation, which have been identified. In order to demonstrate and quantify these effects, we used various encapsulants, but without back protection (foil or glass), and we exposed the samples to different type of atmospheres. The resistivity of the ZnO was monitored using an inductive contactless and a four points probe methods. Finally, schemes to perform highly reliable laminates when using lightly doped ZnO are proposed

NEW PARADIGM FOR REAL-TIME MEASUREMENT AND MAPPING IN a-Si:H/uc-Si:H TANDEM DEVICES

Thin-film Si solar module production requires a fast wide area tool for layer characteristic measurement and control. Non-uniformity in layer deposition is expected to induce loss in module power. Simulations of amorphous Si modules using a two-dimensional model have been used to examine the efficiency loss associated with non uniformity of large scale monolithically integrated thin film modules. The results indicate that non uniform deposition significantly lowers the module efficiency, in a magnitude that varies depending on the shape and orientation of the deposition signature relative to the scribe lines. In order to control the deposition process of individual layers in layer stacks in thin-film PV modules a wide area metrology tools has been developed and tested. Example of layers maps obtained during production of Si layers module are shown. Comparisons of layer characteristics obtained using this tool and values obtained by conventional methods are given to validate the tool performances

Extensive remodeling of DC function by rapid maturation-induced transcriptional silencing

The activation, or maturation, of dendritic cells (DCs) is crucial for the initiation of adaptive T-cell mediated immune responses. Research on the molecular mechanisms implicated in DC maturation has focused primarily on inducible gene-expression events promoting the acquisition of new functions, such as cytokine production and enhanced T-cell-stimulatory capacity. In contrast, mechanisms that modulate DC function by inducing widespread gene-silencing remain poorly understood. Yet the termination of key functions is known to be critical for the function of activated DCs. Genome-wide analysis of activation-induced histone deacetylation, combined with genome-wide quantification of activation-induced silencing of nascent transcription, led us to identify a novel inducible transcriptional-repression pathway that makes major contributions to the DC-maturation process. This silencing response is a rapid primary event distinct from repression mechanisms known to operate at later stages of DC maturation. The repressed genes function in pivotal processes—including antigen-presentation, extracellular signal detection, intracellular signal transduction and lipid-mediator biosynthesis—underscoring the central contribution of the silencing mechanism to rapid reshaping of DC function. Interestingly, promoters of the repressed genes exhibit a surprisingly high frequency of PU.1-occupied sites, suggesting a novel role for this lineage-specific transcription factor in marking genes poised for inducible repressio

Sesame Project - Deliverable D08-02 - WP02 H/V technique : experimental conditions - Final report on Measurement Guidelines

In the following we report the final results for WP02-Measurement Guidelines. This work was conducted under the framework of the SESAME Project (Site Effects Assessment Using Ambient Excitations, EC-RGD, Project No. EVG1-CT-2000-00026 SESAME), Task A (H/V technique), Work Package 02 (WP02 – Measurement Guidelines).European Commission – Research General Directorate Project No. EVG1-CT-2000-00026 SESAMEPublished4.1. Metodologie sismologiche per l'ingegneria sismicaope

A Hydrogenated amorphous silicon detector for Space Weather Applications

The characteristics of a hydrogenated amorphous silicon (a-Si:H) detector are presented here for monitoring in space solar flares and the evolution of large energetic proton events up to hundreds of MeV. The a-Si:H presents an excellent radiation hardness and finds application in harsh radiation environments for medical purposes, for particle beam characterization and in space weather science and applications. The critical flux detection threshold for solar X rays, soft gamma rays, electrons and protons is discussed in detail.Comment: 32 pages, 13 figures, submitted to Experimental Astronom

ExpressWeb: A Web application for clustering and visualization of expression data

The recent explosion of transcriptomics and proteomic data have resulted in vast amounts of datasets without connection and sometime too large to be easily analysed. Integration between datasets and analysis of an extracted datasets are limiting factors which need to be solved in order to make full use of the data and to connect data. ExpressWeb is an online web tool that combines a Taylor clustering of expressed data sets to extract gene network with gene annotations to visualise the co-expression network. Data sets can become from personal or publically experiments. ExpressWeb allows to easily compute clustering on expression data and provides friendly and useful visualisation tools as heatmaps, graphs and networks, generating output images which can be used for scientific publications

Hybrid axial and radial Si-GaAs heterostructures in nanowires

Hybrid structures are formed from materials of different families. Traditionally, group IV and III-V semiconductors have not been integrated together in the same device or application. In this work we present a new approach for obtaining Si-GaAs hybrid heterostructures in nanowires based on a combination of molecular beam epitaxy and plasma enhanced chemical vapor deposition. Crystalline Si segments are integrated into GaAs nanowires grown by the Ga-assisted growth method at temperatures as low as 250 degrees C. We find that one of the most important factors leading to the successful growth of Si segments on GaAs is the silane-hydrogen dilution, which affects the concentration of silicon and hydrogen-based radicals (SiHx with x < 3) in the plasma, and determines if the Si shell is amorphous, polycrystalline or crystalline, and also if the growth takes place in the axial and/or radial directions. This work opens the path for the successful integration of silicon and III-V materials in one single nanowire

Voir les Dieux, voir Dieu

La vision de Dieu, ou des Dieux, est attestée à peu près partout dans l'espace et dans le temps, même là où elle fut réputée impossible en théorie. Elle constitue donc un objet obligé, mais un peu délaissé, de l'histoire des religions. Les douze contributions de ce volume tentent de combler cette lacune en s'interrogeant principalement sur les récits de vision : le témoignage des visionnaires, comme dans d’autres domaines de l'expérience religieuse, est le seul fondement possible d'une analyse historique. Il permet de soulever de multiples problèmes, depuis celui du contenu et des modalités de la vision jusqu'à celui de sa réception et de son éventuelle utilisation. Ces problèmes sont abordés dans divers contextes, depuis l'hindouisme jusqu'au christianisme médiéval d’Occident, en passant par Israël, l'Égypte, la Grèce et la Rome anciennes. Œuvre collective, ce recueil est le fruit de deux journées d'étude organisées en 1998 et 1999 par le Centre de recherches d'histoire des religions de l'université Marc Bloch de Strasbourg, sous la direction de Françoise Dunand et François Bœspflug, professeurs d'histoire des religions

Un outil pour la prise de conscience du risque sismique: les études de scénario. L’exemple de Nice

International audienceLa Côte d’Azur n’est ni le Japon, ni la Californie, loin s’en faut, mais la menace sismique y est réelle. Et pourtant la prévention s’y heurte toujours à une prise de conscience insuffisante. D’où, à l’instar de ce qui se pratique, avec succès, dans des pays plus sismiques, la réalisation d’études de scénario qui devraient permettre l’élaboration d’une politique de prévention. Les principaux éléments de la dernière en date des études conduites à Nice, le projet Gemgep